Characterizing linearity of a large area InGaAs photodiode in direct detection mode, at room temperature, from 100 pA to 10 𝛍A

Nestor Tejedor, Alejandro Ferrero, and Joaquin Campos-Acosta

DOI: 10.1364/AO.537896 Received 06 Aug 2024; Accepted 17 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: Nonlinearity characterization of detectors is necessary for performing measurementsat different radiant flux levels, as it is the case in bidirectional reflectance distribution function(BRDF) measurements. The Differential Spectral Responsivity (DSR) method is one of thetypical procedures for this characterization. In this work, we use attenuation devices to decreasethe response of the detector, while adding a neutral density filter to record its transmittance,which should be constant at the different signal levels. In this work, we intend to use this methodto characterize the linearity of a large area InGaAs photodiode in the near-infrared spectral range,in direct detection mode at room temperature and within a signal range from 10 μA to 100 pA.

Broadband achromatic metalens design based on the combination of improved particle swarm optimized algorithm and genetic algorithm

Pengcheng Sheng, Ruiting Hao, Gang Chen, Wen Wang, Jiatong Liu, Jun Xu, Huizi Li, JinCheng Kong, and Jun Zhao

DOI: 10.1364/AO.539933 Received 20 Aug 2024; Accepted 17 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: Metalenses, a significant branch of metasurfaces, hold substantial applicationpotential. However, they often face issues like chromatic aberration and narrow bandwidth.This paper compares various optimization methods for the inertia weight (ω) and learningfactors (C) of the Particle Swarm Optimization (PSO) algorithm and integrates it with theGenetic Algorithm (GA). After comparison, we selected the optimized algorithm that best fitsour needs to design a broadband achromatic metalens operating in the wavelength range of1μm-1.25μm. The average efficiency reached 76%, providing valuable reference for thedevelopment and application of achromatic metalenses.

Miniaturized Dual-Photodiode Sensor for Simultaneous Wavelength and Irradiance Measurement Across the 500-1000 nm Range

Deok-Young Lee, Gabin YUN, Minseok CHOI, KyuHyeon CHO, Dongwoo LEE, and DONG-HOON Lee

DOI: 10.1364/AO.538616 Received 21 Aug 2024; Accepted 17 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: We introduce a novel chip-scale dual-photodiode sensor capable of simultaneouslymeasuring centroid wavelength and irradiance within the 500-1000 nm range. The sensoremploys a dual-photodiode design, where one photodiode is equipped with a coated filter layerto create differential responsivity, allowing for accurate spectral and intensity detection. Oursensor demonstrates high accuracy, with centroid wavelength and intensity measurements withina 5% margin of error for light sources with a full width at half maximum (FWHM) of 50nm. This design supports the use of optional optical filters tailored to specific wavelengthranges, enhancing adaptability across diverse applications. Experimental validation confirmsits practical potential in a variety of fields, including precision agriculture, horticulture, andenvironmental monitoring, especially for studies involving Far-Red and Near-Infrared lightsources. The chip-scale fabrication of the sensor ensures cost-effective, portable, and scalabledeployment, positioning it as a versatile solution for advancing optical sensing technologies invarious scientific and industrial fields.

Using 3D Printing Technology to Replace the Manufacturing Process of Headlight Lens

Chia Hung Yeh and Heng Yi Lin

DOI: 10.1364/AO.539164 Received 13 Aug 2024; Accepted 17 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: The injection molding technology remains the predominant method formanufacturing plastic optical components, the market is currently trending towards featuressuch as small-batch and diversified production, a streamlined development process, reducedcosts, and swift delivery. The conventional production model faces challenges related toproduction flow, mold cost assessments, expenses associated with hiring skilled professionals,and even a scarcity of talent. Against this backdrop, it is imperative to explore potentialsolutions that can swiftly replace traditional manufacturing processes in order to address theseissues. In this study, we evaluated the feasibility of a headlight lens manufactured using a 3Dprinting process. The results indicate that the lens products manufactured through 3D printingexhibit remarkable precision, with only a 0.558% margin of error regarding the radius ofcurvature of the profile, a surface roughness (Ra value) of 0.020175 μm, and a transmittance of92.54%. One of the key advantages of the 3D printing process is its ability to efficiently realizecomplex structural designs at high speed and low cost. In cases where customization is required,3D printing unquestionably outperforms conventional manufacturing methods.

Frequency-Doubling Optoelectronic Oscillator with Fundamental Frequency Signal Cancellation

Enming Xu, Zhenyang Shi, Qian Shan, Jiaao Liu, and Zuxing Zhang

DOI: 10.1364/AO.540088 Received 21 Aug 2024; Accepted 17 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: A frequency-doubling optoelectronic oscillator (OEO) with fundamental frequency signal cancellation based on adual-polarization Mach-Zehnder modulator (DPol-MZM) is proposed and experimentally demonstrated. In the proposedstructure, two different modulation modes can be utilized to realize the frequency-doubling OEO. One is the carrier-suppresseddouble-sideband (CS-DSB) modulation, and the other is double-sideband modulation (DSB) modulation. In both cases, onepath is used to achieve the fundamental frequency oscillation in the OEO loop through the utilization of an equivalent orconventional DSB modulation, and the other path is employed to realize the frequency-doubled signal. In the realization of thefrequency-doubled signal, the fundamental frequency signal can be cancelled through introducing an additional pure opticalcarrier with proper power and its polarization direction opposite to that of the modulated optical signal. A high sidebandsuppression ratio of the frequency-doubled signal up to 40 dB is achieved.

Multi-particle Size Measurement Using Mie Scattering via Elliptically Arranged Mirror Array

Akitada Sakurai and Jun Sakakibara

DOI: 10.1364/AO.542123 Received 03 Oct 2024; Accepted 17 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: Laser sources have been used to measure micro-scale particle sizes, and various measurement approaches,such as laser diffraction analysis (LDA) and nanoparticle tracking analysis (NTA), have been proposed. Thispaper introduces a novel method that overcomes problems in both of those approaches while successfullycombining their advantages. Our approach can estimate the three-dimensional positions of particlesfloating in water along with their sizes. To measure position and size simultaneously, we used an ellipticallyarranged array of square mirrors to measure the scattering and particle tracking velocimetry (PTV),a methodfor determining the velocity and position of individual particles in three-dimensional space. We validatethe effectiveness of this method by measuring the size distributions of four different standard particlesranging in diameter from 1.3 to 4 micrometers.

Stellar Correction Pointing Model Based on Line-of-Sight Attitude Measurements for Optical Communication Telescopes on Motion Platforms

Zi Wang, peng chao, Tong Zhang, Qiang Wang, Liu Shunfa, xiang liu, Yuan Wang, Yongmei Huang, and Dong He

DOI: 10.1364/AO.540433 Received 29 Aug 2024; Accepted 16 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: Optical Communication Telescopes (OCTs) on motion platforms are essential forthe establishment of global-scale optical communication networks. OCTs with high pointingaccuracy can reduce acquisition time and increase acquisition probability. The pointingaccuracy of OCTs is influenced by mechanical structure errors, structural wobble errors, andattitude measurement errors. Existing pointing error correction models for OCTs on motionplatforms have limitations in addressing these errors. In this paper, we propose an innovativestellar correction pointing model based on line-of-sight (LOS) attitude measurements on motionplatforms to improve the pointing accuracy. Initially, the stellar correction model compensatesfor the attitude measurement errors. Then, guide angles are calculated using the LOS attitude,which eliminates the mechanical structure errors and the structural wobble errors. To validatethe effectiveness of the model, we built an OCT system on a motion platform and conductedstar pointing experiments. The experimental results show that compared with the existingmodel, our model reduces the pointing error by 37.2%, from 24.5 arc-sec RMS to 15.37 arcsec RMS. Therefore, the stellar correction pointing model based on the LOS attitudemeasurements is an effective method for improving the pointing accuracy of OCTs on motionplatforms.

Metal-assisted miniaturized refractive index sensor based on quasi-bound states in the continuum

Zhengweiyi Yang, wang kangni, and Lin Yong Qian

DOI: 10.1364/AO.541172 Received 03 Sep 2024; Accepted 16 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: A miniaturized optical refractive index sensor based on quasi-bound states in thecontinuum (quasi-BIC) is proposed in this work. By utilizing one-dimensional compoundgratings with varying heights to break the symmetry of the grating, the structure supports thetransition from BIC to quasi-BIC. Additionally, metallic mirrors are positioned at the edges ofthe grating to facilitate effective in-plane light confinement, thereby reducing light leakage andsignificantly enhancing peak efficiency within constrained dimensions. A comprehensiveinvestigation was conducted to analyze the impact of metal height, edge spacing, and thenumber of periods on the resonance modes in finite structures, with the aim of optimizingstructural parameters. An assessment of refractive index sensing performance was performedunder TE and TM polarizations. The results indicate that the sensitivities for TM and TEpolarizations are 427 nm/RIU and 434 nm/RIU, with a small footprint of approximately 18.51μm and 18.48 μm, respectively. This study has the potential to enhance the design andapplication of miniaturized optical refractive index sensors.

Fluorescence-Signal Imaging Polarimetry for Characterization of Mexican Honeys

Juan Lopez-Tellez, Claudio Frausto-Reyes, Martin Ortiz-Morales, Manuel De la Torre I., Ricardo Valenzuela, and Rafael Casillas

DOI: 10.1364/AO.541476 Received 05 Sep 2024; Accepted 16 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: A methodology that combines fluorescence spectroscopy, image polarimetry, and ananalytical technique for processing experimental data to characterize and classify Mexicanmonofloral and multifloral honey is presented. Honey samples were excited with a 397 nm laserbeam to produce a fluorescence signal, polarization images were acquired using a polarizedCMOS sensor to perform polarimetric measurements, and a spectrometer was employed formeasuring the produced fluorescence spectra. Image-based measurements are more appropriatefor studying crystalized honey samples than point-signal measurements. Honey fluorescenceproduces partially polarized light when excited with linearly polarized light. According to ourresults, the degree of linear polarization is related to the botanical origin of the honey samplesand their crystallization state. Three different classification methods are presented, and theresults indicate a good agreement among them.

Dual-liquid zoom lens with free liquid surface controlled by sidewall slope

huibin liu, Rongrong Xu, Tao Chen, Peitao Zheng, Jing Chen, and Rongqing Xu

DOI: 10.1364/AO.542714 Received 19 Sep 2024; Accepted 16 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: In this paper, a dual-liquid zoom lens with an adjustable focal length by controlling the slope of the sidewall is proposed. Different from the straight barrel or cube-cone type of the traditional liquid lens, the slope of the sidewall of the proposed liquid lens changes continuously in the direction of light transmission. The height of the three-phase contact line is controlled only by applying an external force to change the direction of the solid-liquid interfacial tensions due to changes in the slope of the sidewall. We selected four different structures to discuss diopter variation. The optimum diopter variation is (-26.73D, 16.59D). In addition, our device provides a novel idea for the structural design of the liquid lens.

An Image Motion Compensation Control Method for the Dynamic Scan and Stare Imaging System

Peng Gao, Xiuqin Su, Zhibin Pan, Ruoyu Liu, Wenbo Zhang, Yu Cao, and Lin Wang

DOI: 10.1364/AO.545170 Received 17 Oct 2024; Accepted 16 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: The main function of the dynamic scan and stare imaging system is to quickly andcontinuously search a large area and perform high-resolution imaging. To eliminate imagemotion during the scanning process, this paper proposes an image motion compensationcontrol method with dual channel control. Firstly, an improved model-assisted activedisturbance rejection control is proposed, in which an auxiliary model is integrated into thealgorithm to improve the control accuracy and response speed of the rotation rate of theplatform. Secondly, a fast steering mirror (FSM) is introduced into the control system tocompensate for the scanning speed and multiple disturbances. By adopting the amplitudefrequency characteristics of the tracking differentiator, a parallel tracking differentiator filteris designed to suppress the interference of gyroscope noise on the FSM. When the system isdisturbed by multiple frequency disturbances, the residual error of the image motioncompensation is less than the spatial angular resolution of one pixel through the dual channelstable control of the platform and the FSM. In the scan imaging experiment results, theaverage value of the grayscale variance function for the compensated images is close to 90%that of the static reference images.

A Method for Simultaneous Reconstruction of Depth and Clear Image with Single Blurred Image in Microscopy

Yangjie Wei and Xinyu Di

DOI: 10.1364/AO.540958 Received 04 Sep 2024; Accepted 15 Nov 2024; Posted 15 Nov 2024  View: PDF

Abstract: Evaluation of imaging blur degradation characteristics of high-magnification optical microscopes is greatly influenced by complex imaging mechanisms, image textures, and illumination, resulting in low accuracy and poor generality, which seriously limits the observation precision at the micro-nano scale. This paper proposes a method for simultaneous reconstruction of depth and clear image of a blurred image based on the light intensity distribution law of the microscopic imaging system. First, based on the diffraction characteristics of the light in the circular stable cavity, the light intensity distribution function on the imaging plane of the imaging system is established, and the law of the light intensity diffusion degree with the scene depth variation is obtained by curve fitting, that is, the 3D blur degradation model of the system. Second, the normalized blurring degree of blurred images with different textures and different illumination is calculated, and the mapping relationship between the blurring degree of different images and the light intensity diffusion degree of the system is established with the depth change as the intermediate variable. Third, an adaptive spectral clustering method is introduced to classify the blurred images, and the weighted K-nearest neighbor method is used to automatically classify any blurred image and calculate its normalized blurring degree value and the corresponding system energy diffusion value. Based on the 3D blur degradation model and the normalized blurring degree, the depth calculation of the blurred image and the reconstruction of the clear image are realized simultaneously. The precision of the method proposed in this paper is verified by various standard nano-scale grid images, and the potential application of our method in the field of high-precision observation of biological samples is verified by experiments on various real biological tissue samples.

Optical properties and phase matching conditions of KTiOPO₄ crystals at terahertz frequencies in the temperature range of 5.8 to 300 K

Gaofang Li, Rongyang Liu, hanjing ye, jingguo huang, Haoyang Cui, Yanqing Gao, Zhiming Huang, and Junhao Chu

DOI: 10.1364/AO.536721 Received 17 Jul 2024; Accepted 15 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: In this paper, the optical properties and phase matching (PM) conditions of KTiOPO₄ (KTP) crystals in the temperature range of 5.8 ~ 300 K are studied by terahertz (THz) time-domain spectroscopy. It is found that the absorption coefficient of KTP decreases with the decrease of temperature, and that of Z axis at 1.2 THz decreases from 19.56 cm¯¹ at 300 K to 7.83 cm¯¹ at 5.8 K. Along the Z axis, the refractive index decreases with the decrease of temperature and changes the most, while along the X and Y axes, the refractive index is relatively stable with temperature. The optical properties along the Z axis are sensitive to temperature, mainly because the movement of K+ is located in the Z axis and slows down with the decrease of temperature. KTP crystals are found to have obvious birefringence characteristic in the frequency range of 0.3-1.6 THz, with the birefringence of approximately 0.67 at 300 K and 0.58 at 5.8 K. The PM angle is calculated using the refractive index dispersion equation to satisfy the PM condition of frequency transformation. When the temperature is lowered from 300 K to 5.8 K, the maximum change in PM angle is 1.08°, while the minimum change is 0.10° at same output wavelength. Due to the small absorption coefficient and the birefringence characteristics at low temperatures, and the relatively stable change of PM angle with temperature, the potential of KTP crystals to efficiently generate THz radiation at low temperatures can be fully realized.

Terahertz perfect absorber of narrowband and broadband based on a U-shaped metal patch

Zhen Zhang, Huan Zhou, Linji Yang, Yandong Xiao, xin chen, Yong Ma, and Renpu Li

DOI: 10.1364/AO.538694 Received 06 Aug 2024; Accepted 15 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: This letter proposes a terahertz absorber based on a U-shaped metal patch that exhibits both narrow-band and wideband absorption characteristics. The absorber comprises a metal-medium-metal structure, with a U-shaped metal patch as thetop layer, a lossy medium as the middle layer, and a fully covered metal base plate at the bottom. There are two narrow-bandabsorption peaks at 1.368 THz and 2.648 THz and a broadband absorption band from approximately 4 to 5 THz. The formationof resonance frequencies was elucidated by analyzing the current and electric field distributions at the resonance frequency. Theresonant mechanism of the U-shaped patterned structure was clarified using equivalent circuit models to evaluate the resonantfrequencies of different absorption peaks. Subsequently, the absorber's characteristics were examined under varying structuralparameters. Dual-function terahertz absorbers are applicable in terahertz communications, imaging, and various other fields.

Improved PGC-Arctan Demodulation AlgorithmBasedonRealtime Feedback Control

Qiang Ge, Wen-chao He, Jian Xiao, Linguang Xu, and Gang Zhang

DOI: 10.1364/AO.543813 Received 01 Oct 2024; Accepted 15 Nov 2024; Posted 18 Nov 2024  View: PDF

Abstract: The Phase generated carrier (PGC) demodulationalgorithm has the characteristics of high accuracy, goodlinearity and large dynamic range which makes it widelyused in interferometric fiber optic sensors. However, dueto the influence of carrier phase delay (CPD), phasemodulation depth (C), and light intensity disturbance, thesystem introduce nonlinear distortions. To address thisproblem, we proposed a highly stable PGC demodulationalgorithm that combines CPD compensation and C self- calibration. Multitone mixing is used in the CPDcompensation and C self-calibration. The CPDcompensation algorithm calculates CPD using theharmonic components and their differential componentsobtained from two orthogonal carrier signals, and usesCPD to set the initial phase of the reference carrier toobtain the harmonic components that eliminate theinfluence of CPD. The C self-calibration algorithmcalculates the real-time C by the ratio of the twoharmonic components, and introduces Proportional- Integral-Derivative control (PID) to stabilize C at theoptimal value by controlling the output voltage. Theexperimental results show that the standard deviation ofthe CPD calculated by the CPD compensation algorithm is0.0012 rad. The real-time modulation depth of thesystem can quickly reach the optimal value and maintainit for a long time. The average phase modulation depth is2.63 rad with a standard deviation of 0.00735 rad. Compared with the traditional PGC-Arctan demodulationalgorithm, our algorithm yields higher SINADs and lowerTHDs under different CPDs, the average SINAD is 62.68dB, and the THD is 0.075%.

Hardware Simulation of Real-time Wavelength Corrected Phase Projection

Paul Sibley, Noah Baldwin, Michael Ireland, and Chathura Bandutunga

DOI: 10.1364/AO.540085 Received 21 Aug 2024; Accepted 13 Nov 2024; Posted 13 Nov 2024  View: PDF

Abstract: We demonstrate, in hardware simulation, the real-time operation of a dispersion-free phase projection algorithm for atmospheric correction of multi-aperture optical phased arrays. It uses interferometric phase measurements at multiple sensing wavelengths, offset by 50 GHz, to compute a phase correction at a third, remote wavelength. This is useful where phase sensing cannot be implemented at the wavelength of interest. The digital signal processing implementation we demonstrate a residual error of 4x 10^(-4) rad}/sqrt(Hz) while being capable of 100 MHz throughput with 0.53 μs latency, making it a viable approach for either feedback or feed-forward segmented adaptive optics control systems.

DL-CSPF: Deep learning-based cell segmentation with a physical framework for digital holographic microscopy

zhuoshi li, Hao Gu, Linpeng Lu, Qian Shen, Jiasong Sun, Qian Chen, and Chao Zuo

DOI: 10.1364/AO.546044 Received 24 Oct 2024; Accepted 13 Nov 2024; Posted 13 Nov 2024  View: PDF

Abstract: Digital holographic microscopy (DHM) offers label-free, full-field imaging of live-cell samples by capturing optical path differences to produce quantitative phase images. Accurate cell segmentation from phase images is crucial for long-term quantitative analysis. However, complicated cellular states (e.g., cell adhesion, proliferation and apoptosis) and imaging conditions (e.g., noise and magnification) pose significant challenge to the accuracy of cell segmentation. Here, we introduce DL-CSPF, a deep learning-based cell segmentation method with a physical framework designed for high-precision live-cell analysis. DL-CSPF utilizes two neural networks for foreground-background segmentation and cell detection, generating foreground edges and “seed points”. These features serve as input for a marker-controlled watershed algorithm to segment cells. By focusing on foreground edges and “seed points”, which have lower information entropy than complete cell contours, DL-CSPF achieves accurate segmentation with a reduced dataset and without manual parameter tuning. We validated the feasibility and generalization of DL-CSPF using various open-source and DHM-collected datasets, including HeLa, Pollen, and COS-7 cells. Long-term live-cell imaging results further demonstrate that DL-CSPF reliably characterized and quantitatively analyzed the morphological metrics across the cellular lifecycle, rendering it a promising tool for biomedical research.

Wireless UV Collaborative RSSI and AOA Hybrid Localization Method for UAV swarms

Taifei Zhao, Mina Li, Jiachen Liu, Yunpeng Wang, and Hui Li

DOI: 10.1364/AO.536756 Received 17 Jul 2024; Accepted 13 Nov 2024; Posted 13 Nov 2024  View: PDF

Abstract: Wireless ultraviolet (UV) light can guarantee the inter-copter positioning accuracyof cluster-flying unmanned aerial vehicles (UAVs) in electromagnetic confrontationenvironment. By combining wireless UV received signal strength Indication (RSSI)localization and Angle of Arrival (AOA) localization algorithm, a UV-Hybrid localizationmethod is proposed for UV communication collaboration between UAV swarms. The methodcollects the UV signal strength between the anchor UAV node and the unknown UAV node toobtain the inter-aircraft distance information, establishes a Gaussian hybrid noise model basedon semidefinite relaxation, and uses the UV angle of arrival estimation to solve the anglebetween the UAVs to achieve the maximum likelihood estimation of node positions in UAVswarms. Simulation comparison of UV hybrid localization algorithm, weighted least squaresand Gaussian hybrid semi-definite planning localization algorithm is carried out, and the resultsshow that: the performance of UV hybrid localization algorithm is close to the Cramer–Raolower bound, and the average localization error is reduced by 32.9% and 15.6% compared toweighted least squares and Gaussian hybrid semi-definite planning algorithms, and thealgorithm of this paper achieves the node localization with less iterations, and has a higheraccuracy and efficiency of localization than the other algorithms.

Optical Properties of Nanoparticles in Blood: Considering Blood Absorption

Ning Cheng, Xingcai Li, Juan Wang, and Xin Ma

DOI: 10.1364/AO.540304 Received 28 Aug 2024; Accepted 13 Nov 2024; Posted 13 Nov 2024  View: PDF

Abstract: Nanomedicine is emerging as a crucial avenue for exploring new therapeutic and diagnostic techniques in the medical field. Effective monitoring of the dispersion concentration of nanoparticles using optical methods is an extremely important topic in this area. However, existing research has not recognized that the light absorption of blood can lead to significant errors in related optical measurements. This paper, considering the absorption properties of the background medium, meticulously discusses the variations in the single-scattering characteristics of nanoparticles in plasma and whole blood, and analyzes the influence of parameters such as incident wavelength, particle size, refractive index, and background medium refractive index. The results indicate that neglecting the light absorption of the background medium may lead to differences of up to approximately 50% in the results, but this is also influenced by parameters such as incident wavelength, particle size, and refractive index. Furthermore, there are still significant differences in the variations of the single-scattering properties of nanoparticles with identical characteristics in plasma and whole blood. These results indicate the importance of in-depth research into calibration techniques for optical instruments in monitoring nanoparticles in the blood, and further enhance the development of nanoparticle monitoring technology in nanomedicine.

Freeform mirror design for beam shaping by a combined approach using Poisson-based grid optimization and discrete cosine transform

shengzhi xu, Zhouping Su, and Ming Lei

DOI: 10.1364/AO.542603 Received 18 Sep 2024; Accepted 13 Nov 2024; Posted 13 Nov 2024  View: PDF

Abstract: In this study, we have designed freeform mirrors capable of transforming uniformirradiance distribution into complicated irradiance distribution. The design methodologyincorporates two key algorithms: Poisson-based grid optimization and discrete cosine transform(DCT). The grids on the target plane were optimized using Poisson-based grid optimizationwhile maintaining uniform on the incident plane. By obtaining grids for both input and targetplanes, we derived the normal vector field and utilized DCT to calculate the sags of the freeformsurface. Several examples have been devised to substantiate the validity of the approach. ForCase 1and Case 2, the results demonstrate that these freeform surfaces produce high-contrastand complicated irradiance maps with a notable proportion exceeding 4:1 in terms of irradiationintensity ratio between graphic area and background. In Case 2, when compared to theprescribed irradiance distribution, the NCC (Normalized Cross Correlation) values forgenerated irradiance distributions by the freeform mirror, both with and without sag error, are94% and 96%, respectively. Furthermore, Cases 3 and 4 demonstrate that incident beams withcomplex irradiance distributions can be transformed into uniform irradiance profiles by thefreeform mirror designed using the proposed method, achieving uniformity levels of 93% and95%, respectively. It is noteworthy that the incident beam aperture in Case 4 exhibits anelliptical shape.

Verification of single-photon path entanglement using a nitrogen vacancy center

André Smith, Christine Steenkamp, and Mark Tame

DOI: 10.1364/AO.542615 Received 20 Sep 2024; Accepted 13 Nov 2024; Posted 13 Nov 2024  View: PDF

Abstract: Path entanglement is an essential resource for photonic quantum information processing, including in quantum computing, quantum communication and quantum sensing. In this work, we experimentally study the generation and verification of bipartite path-entangled states using single photons produced by a nitrogen-vacancy center within a nanodiamond. We perform a range of measurements to characterize the photons being generated and verify the presence of path entanglement. The experiment is performed using continuous-wave laser excitation and a novel state generation `time-window' method. This approach to path entanglement verification is different to previous work as it does not make use of a pulsed laser excitation source.

Thermal lens focal length statistics for end-pumped solid-state lasers excited with different beam shapes

Sofiane HADDADI, Bencheikh Abdelhalim, and Kamel Ait-Ameur

DOI: 10.1364/AO.543236 Received 30 Sep 2024; Accepted 13 Nov 2024; Posted 13 Nov 2024  View: PDF

Abstract: Recent researchs has explored the use of non-Gaussian beams, such as ring-shaped pump beams, inend-pumped solid-state lasers to reduce thermal lensing effects. Theoretical studies indicate that thethermal lens is not constant but varies with the radial coordinate r, and can be modeled with two or threecomponents depending on the pumping beam profile Top-Hat or ring-shaped, respectively. This paperintroduces a new single-component expression for the thermal lens, derived from the mean value andstandard deviation, which is applicable to various pump beam shapes. The results show that the ringshaped beam produces the lowest average thermal lens dioptric power, with the Top-Hat beam followingclosely, exhibiting similar power to the Gaussian beam. These findings align with experimental datareported in the literature. This new approach simplifies the representation of the thermal lensing, offeringa more accurate method for correcting its effects.

PE-INeR: Prior-Embedded Implicit Neural Representation for Sparse-View CBCT Reconstruction

Jiaying Yang and Shipeng Xie

DOI: 10.1364/AO.534352 Received 02 Jul 2024; Accepted 13 Nov 2024; Posted 14 Nov 2024  View: PDF

Abstract: Conventional methods for reconstructing CBCT often suffer from artifacts and blurring in the presence ofmissing data, which ultimately hampers the quality of the resulting images. To address this challenge, wepropose a neural implicit representation method (PE-INeR) based on prior embedding for sparse-view CBCTreconstruction. In our proposed method, we leverage prior information to guide the reconstruction process.By employing a neural implicit representation network, we capture the intricate features of the image in animplicit manner. Our experimental results underscore the superiority of our approach, demonstratingremarkable reductions in artifacts and substantial enhancements in image quality compared to traditionaltechniques. Moreover, it is important to emphasize that the PE-INeR outperforms alternative methods ineffectively capturing nuanced yet critical image variations, which play a pivotal role in precisely evaluatingthe advancement of tumors.

Compact Cavity-Enhanced Aerosol Detector using Incoherent Light Sources

Jacob Williamson, Pranav Muthukrishnan, Srushti Nandanwar, Shuaifeng Guo, and Chandra Raman

DOI: 10.1364/AO.540296 Received 26 Aug 2024; Accepted 13 Nov 2024; Posted 14 Nov 2024  View: PDF

Abstract: We have realized a compact optical particle counter utilizing enhancement of lightscattering within a high finesse Fabry-Perot optical cavity. In contrast to laser-based approachessuch as cavity ringdown spectroscopy we use the light stream from both superluminescentand light-emitting diodes that have no longitudinal coherence. This eliminates the vibrationsensitivity that is typical of laser-based cavity methods. The use of the transmission mode ofdetection allows us to reduce the cavity mirror separation to below 1 cm, with no obvious limit tominiaturization. Typical light scattering instruments are larger, in part due to their sensitivity tobackground signals from the light source. Our approach paves the way toward a new generationof compact and portable instruments. A simultaneous comparison of the scattering signals with a commercial particle counter suggests that our cavity may be sensitive to ultrafine particles below300 nm diameter that are typically not recorded in such counters.

Wavelength optimization of fine optical surface defect detection based on FDTD

Shaowen Wang, Lan Wu, Shiling wang, Dong Liu, Shiwei guo, Xulongqi Wang, Bingwen Jin, Zhiji Deng, Miao Cheng, Ming Liu, and Zhewei Fu

DOI: 10.1364/AO.542148 Received 12 Sep 2024; Accepted 13 Nov 2024; Posted 14 Nov 2024  View: PDF

Abstract: Due to the similar order of magnitude of the defect size and the detection wavelength, when detecting micro-/nano-scale defects on the surface of a fine optical component, the intense modulation of the optical field poses challenges in correlating imaging widths of defects with actual widths. A dark-field scattering imaging (DFSI) model, based on the Finite Difference Time Domain (FDTD) method, is established to study the imaging for triangular and circular section defects and investigate the influence of wavelength on defect width detection. Simulated results indicate that a shorter wavelength of the light source in a DFSI detection system leads to a larger mapping range between the imaging width and the actual defect width, which makes calibration less difficult. A DFSI detection system for micro-/nano-scale surface defects on optical components is built to test defects with rectangular cross-section on a calibration board. The defect widths estimated from the experimental and simulated results are in good agreement, with a Root-Mean-Square Error (RMSE) of 0.11μm.

Design of dual-band common aperture confocal plane optical system

You HongBo, Yang JiaQiang, Li JiangYong, Zhang Sai, and Zhang Tian

DOI: 10.1364/AO.543163 Received 27 Sep 2024; Accepted 13 Nov 2024; Posted 14 Nov 2024  View: PDF

Abstract: In order to achieve high-quality imaging while simplifying the structure and reducing the sizeof the optical system, a miniature dual-disc folding reflection optical system was designed. A designapproach incorporating reflector fitting is employed, the adjacent reflector is fitted to one mirror. Theoptimized optical system contains two mirrors, and the system length-to-focal length ratio is 0.325,which significantly reduces the axial distance of the system. Furthermore, the engineering of the opticalsystem was successfully achieved. The experimental results demonstrate that the captured imagesdisplay consistent clarity, are free from distortion, and meet the specified design requirements

Deep learned processing of coherent diffractive correlators signals

Evgenii Zlokazov, Rostislav Starikov, and Dmitriy Goncharov

DOI: 10.1364/AO.541305 Received 10 Sep 2024; Accepted 12 Nov 2024; Posted 12 Nov 2024  View: PDF

Abstract: Deep learning neural networks a known for high precision of object recognition, however processing of high resolution images requires a lot of calculations during training and inference. On the other hand optical Fourier-processors and correlators provide highly parallel calculations robust to electromagnetic interference and potentially energy efficient. Given article shows the results of both approaches synergetic implementation as coherent diffractive correlator with deep learned digital post-processing of output correlation field. We demonstrated that output signals of optical correlators being captured by low resolution sensor can be efficiently classified by a deep neural network that was trained on numerically generated database of correlation responses. The results of processing of output signals of experimental implementations of both 4-f and 1-f optical schemes showed that input images of 256x256 pixels can be efficiently classified by extracting and processing of regularly downsampled correlation responses with resolution as low as 16x16 or 8x8 pixels.

Multi-region phase response calibration of SLM based on Shack-Hartmann Wavefront Sensor

zhai zhongsheng, Yuxuan Jia, Zhen Zeng, Wei Feng, and Da Liu

DOI: 10.1364/AO.542132 Received 12 Sep 2024; Accepted 11 Nov 2024; Posted 12 Nov 2024  View: PDF

Abstract: In order to accurately measure the phase modulation capability of spatial light modulator(SLM) and improve its performance in optical applications, a multi-region phase response calibrationscheme of SLM based on Shack-Hartmann wavefront sensor (SHWS) is proposed. This schemeaddresses the nonlinear sampling issue of the liquid crystals in different sampling areas on the SLM. Byloading and shifting dual sine phase patterns, continuous variations of grayscale values in the same regionon the SLM screen were achieved, with the corresponding wavefront data recorded by the SHWS aftereach grayscale change. Matrix calculations were performed in MATLAB to obtain the correspondingphase modulation curve. Subsequently, the multi-zone phase modulation characteristics of the SLM weremeasured. Following the nonlinear calibration of phase modulation in each zone of the SLM, the intrinsicwavefront distortion (WFD) of the SLM was measured using the SHWS in conjunction with thecalibration results and compensated for. The compensated WFD of the SLM is reduced from 0.7976 λto 0.3415 λ (λ = 632.8 nm). And in the verification experiment, the focused spots quality was greatlyimproved with the calibrated SLM. The experimental results proved the availability of the multi-regionphase response calibration scheme. Compared to conventional methods, this approach demonstratessimplicity, real-time performance and robustness.

Application of the Hilbert-Huang Transform to evaluate signals in chromatic confocal spectral interferometry

Yulu Zhao, Songtao Chang, Yi Zhang, and haojie xia

DOI: 10.1364/AO.544399 Received 09 Oct 2024; Accepted 11 Nov 2024; Posted 12 Nov 2024  View: PDF

Abstract: Chromatic Confocal Spectral Interferometry (CCSI) is ahybrid measurement technique that integrates theprinciples of Spectral Interferometry and ChromaticConfocal Microscopy. This innovative approach enablesscanning-free acquisition of axial dimensions whileleveraging interferometric methods to enhance depthaccuracy. This feature allows the CCSI signal to beprocessed using both peak extraction and evaluation ofthe interferometric optical path length difference. Thephase information offers a decreased measurementuncertainty, making it a commonly used approach inexisting studies. Methods such as Fourier Transform (FT)and Wavelet Transform (WT) are frequently employed forthis purpose. In this paper, we present a signal processingapproach based on the Hilbert-Huang Transform (HHT).Through simulations and experiments, we compare HHTwith Fourier Transform (FT) and Wavelet Transform(WT), demonstrating its stability, noise resistance, andeffectiveness in phase extraction for CCSI measurementsignals. Additionally, we leverage the characteristics ofCCSI signals and the time-frequency analysis capabilitiesof HHT to address the direction ambiguity problem inwhite-light interferometry.

Silicon-based three-dimensional waveguide mode switch based on phase change material

Mu Zhu, Shijie Sun, Tianhang Lian, Yuanhua Che, Xueqing Sun, Daming Zhang, and Xibin Wang

DOI: 10.1364/AO.542993 Received 23 Sep 2024; Accepted 11 Nov 2024; Posted 12 Nov 2024  View: PDF

Abstract: The mode division multiplexing (MDM) technology can transmit multiple modes simultaneously in the few-modefiber or waveguide, which can effectively improve the data transmission capacity in the process of opticalcommunication. In this paper, we report a silicon-based three-dimensional waveguide mode switch based on phasechange materials (PCMs), which uses two asymmetric directional couplers (ADCs) structure. The two ADCs use acommon few-mode waveguide as the underlying bus waveguide, and the upper layer is composed of two differentsingle-mode waveguides covered with thin PCM as the access waveguides. By using this structure and changing thecrystal phase of the PCM, it is possible to achieve the mode switching between the mode TE11 to TE21 and the modeTE11 to TE12. The designed 3D mode switch has excess loss <2.64 dB and crosstalk < -15.4 dB in the operatingwavelength of 1500-1600 nm.

Design and analysis of Far-Infrared Metamaterial Perfect Absorber with sensing applications

Ankit ., Kamal Kishor, and Ravindra Sinha

DOI: 10.1364/AO.538864 Received 08 Aug 2024; Accepted 11 Nov 2024; Posted 12 Nov 2024  View: PDF

Abstract: In this paper, we present analysis and design of a metamaterial as a perfect absorber and refractiveindex sensor in the far infrared (IR) region, utilizing the finite element method (FEM). The structure consists of ametal resonator on a silicon dielectric with a bottom copper layer beneath the dielectric. Our results demonstratethat the designed structure achieves nearly perfect absorption of transverse electric (TE) polarization at aresonance wavelength of λr = 9.40 µm. This occurs because of the perfect impedance matching condition, whichachieves a 99.47% absorption efficiency. This condition is also sensitive to the angle of incidence and causesminimal reflection at the resonating wavelength of 𝜆𝑟. This characteristic makes the designed metamaterialstructure suitable for use as a sensor. The structure enables maximum electric field confinement in the gap region(g) of the Split Ring Resonator (SRR) at the metal-dielectric interface. The resonance wavelength can beeffectively tuned and optimized by varying the gap size (g), dielectric material, dielectric thickness (𝑡𝑑), copperlayer thickness (𝑡𝑐), and the incident angle of the metamaterial absorber (MA). The absorption peak shows ahighly sensitive response to changes in the refractive index of the surrounding medium, with a sensitivity of1600 nm/RIU. This absorber, with its excellent absorption in the far IR spectrum, holds promising potential forapplications in energy harvesting and IR sensing.

Liquid crystal based diffractive optical elements with high Pancharatnam-Berry phase accuracy for holographic displays fabricated using an optimized Liquid Crystal on Silicon device

Weijie Wu, Chongkai Wang, Mike Pivnenko, Xin Chang, and Daping Chu

DOI: 10.1364/AO.539986 Received 26 Aug 2024; Accepted 11 Nov 2024; Posted 12 Nov 2024  View: PDF

Abstract: A rapid and accurate photoalignment technique was proposed for the fabricationof liquid crystal Pancharatnam-Berry phase diffractive optical elements (LC PB-DOEs). Thein-plane orientation of LCs was precisely manipulated through the polarized illumination of anoptimized liquid crystal on silicon (LCOS) device. LCOS and thereafter spatial light modulator(SLM) can generate polarization patterns at pixel level at will. The quality of such alignmentwas improved significantly by minimizing the phase flicker of the phase-only LCOS SLM. Thiswas confirmed by the increase of the measured quality of the holographic images reconstructedusing our DOE in terms of structural similarity (SSIM) and peak signal-to-noise ratio (PSNR) at30% and 5%, respectively. Furthermore, a bi-focal LC PB-lens was fabricated and used as a highquality Fourier lens in holographic display to validate the usefulness of such LC PB-DOEs. Thiswork illustrated a ubiquitous approach of fabricating different types of lightweight and thin form factor DOEs of random phase patterns at pixel level with low-cost and high throughput.

Design and FDTD simulation of a remote-controllable visible-light plasmonic waveguide and refractive-index-sensitive switch

Peng Yang, Yu Chen, and Fangping Ouyang

DOI: 10.1364/AO.538822 Received 19 Aug 2024; Accepted 10 Nov 2024; Posted 11 Nov 2024  View: PDF

Abstract: In this paper, a plasmonic switch based on metal-insulator-metal (MIM)waveguide structure is proposed, whose transmission characteristics can be remotelycontrolled by a rake switch design. The distance from the remote control unit to the buswaveguide is more than 1um and still maintains a very high efficiency. The refractiveindex-dependent transmission spectrum of this filter was simulated using thefinite-difference time-domain method. The results show that the ON/OFF switching ofwave propagation in the bus waveguide can be achieved by changing the refractive indexof the control unit 1 µm away from the bus waveguide. A change in refractive index ofonly 0.2 is required to simultaneously control the switching off and on of four waves inthe waveguide in the visible band, with corresponding switching ratios of 40.5, 74.3, 48.6and 15.1, showing great potential for applications in refractive index sensors and remotelycontrollable band stop filters.

Multiple color information cryptosystem using Hessenberg decomposition modulated chaotic and face biometric phase encoding

Muhammad Abuturab

DOI: 10.1364/AO.538132 Received 05 Aug 2024; Accepted 10 Nov 2024; Posted 15 Nov 2024  View: PDF

Abstract: A novel multiple color information cryptosystem based on Hessenbergdecomposition (HD)-modulated chaotic and face biometric phase encoding is introduced. Theface biometric phase mask (FPM) and chaotic phase mask (CPM) are modulated by HD toobtain an upper Hessenberg matrix, an upper triangular matrix, and two unitary matrices forthe first time. Each original color image is decomposed into R, G, and B channels. Eachchannel is individually modulated by an upper triangular matrix and two unitary matrices. Theupper Hessenberg matrix and modulated R, G, and B channels are inverse discrete wavelettransformed to produce a fused image. In the same way, fused images for multiple color imagesare generated and combined into a single complex image, which is bonded with a first chaoticface biometric phase mask (CFPM) and fractional Fourier transformed. The resultant image isamplitude- and phase-truncated to generate the first common decryption key and preliminaryencrypted image. The encrypted image is bonded with a second CFPM and fractional Fouriertransformed. The obtained image is amplitude- and phase-truncated to generate the secondcommon decryption key and final encrypted image. The proposed method utilizes the fusedimage as a covered image to conceal the modulated R, G, and B channels of each original colorimages. Furthermore, six decryption keys (three matrix decryption keys, one individualdecryption key, two common decryption keys), and six encryption keys (two CFPMs and fourorders of fractional Fourier transform) provide resistance against various types of potentialattacks. A hybrid optoelectronic system can be utilized to implement the proposedcryptosystem. Numerical simulation results validate the feasibility and efficiency of theproposed scheme.

Development of an optical method to align a high-flux solar furnace

Leopoldo Martinez-Manuel, Carlos Arreola-Ramos, Argelia Ortea, and Camilo Arancibia-Bulnes

DOI: 10.1364/AO.536637 Received 16 Jul 2024; Accepted 09 Nov 2024; Posted 11 Nov 2024  View: PDF

Abstract: High-flux solar furnaces are valuable tools for applied research and development in solar energy. However, misalignment of concentrator facets can produce optical losses and lower the concentration ratio of these systems. This study proposes a practical method to align the solar furnace of UNAM´s Instituto de Energías Renovables. The optical method uses a computer projector that illuminates the facets with a well-defined light pattern to quantitatively and qualitatively determine any misalignment associated with the mirrors. Through the Monte Carlo ray-tracing technique, the complete solar furnace, the projector, and the observation plane are optically modeled for the development of the methodology. A theoretical sensitivity analysis of the technique is reported along with the experimental validation of the determined mirror misalignments, which results in a detection accuracy of 0.32 mrad.

Nonlinearity Mitigation in Bandwidth Limited Blue LED-based OFDM-UOWC Systems using Differential Pre-emphasis

GOPAL KRISHNA, Jimson Mathew, and Sumanta Gupta

DOI: 10.1364/AO.540838 Received 04 Sep 2024; Accepted 08 Nov 2024; Posted 08 Nov 2024  View: PDF

Abstract: Direct current optical orthogonal frequency division multiplexing (DCO-OFDM) is widely used in blue light emitting diode (LED) based underwater optical wireless communication (UOWC) but the limited LED bandwidth leads to nonlinear distortions at higher frequencies. This paper proposes and validates using experiments a differential pre-emphasis (DPE) scheme for OFDM signal transmission in underwater channels to mitigate LED modulation bandwidth-induced nonlinearity, therefore improving the transmission system performance. It is shown that the optimum DPE value leads shorter rise time and fall time of the received signal and also avoids over- and under-shoots. The DPE scheme is validated through numerical simulations for QPSK, 16-QAM, and 64-QAM at symbol rates of 10 MS/s, 20 MS/s, and 25 MS/s, respectively, with an LED bandwidth of 8 MHz. The bit error rate (BER) performances are estimated at different values of the DPE factor for each modulation format and symbol rate. The simulation results indicate an optimized modulation format and symbol rate depenedent DPE factor for achieving minimum BER values. We further validate the DPE scheme on QPSK, 16-QAM, and 64-QAM-based OFDM transmissions in a 2.5 m tap water UOWC experimental setup. Results confirm that the optimized DPE factor depends on the modulation format and symbol rate for achieving the best BER performance. Experimental results show that DPE scheme improves BER performance significantly, providing over four orders of BER improvement for all modulation formats at their respective maximum symbol rates. Successful transmissions of OFDM signal at data rates of 24.09 Mb/s for QPSK, 48.19 Mb/s for 16-QAM, and 72.28 Mb/s for 64-QAM using 8 MHz blue-LED-based transmitter in the presence and absence of air bubble-induced turbulence in the water channel are experimentally demonstrated in this paper.

High-Sensitivity Ocean Temperature Sensor Using Reflective Optical Microfiber Coupler and Machine Learning Methods

Yan Xu, Yuren Chen, Chenghao Cui, Wenhao Lv, and xiaojuan liu

DOI: 10.1364/AO.540324 Received 02 Sep 2024; Accepted 07 Nov 2024; Posted 08 Nov 2024  View: PDF

Abstract: This article proposes a novel seawater temperature sensor, which utilizes an optical microfiber coupler combined with a reflective silver mirror (OMCM). The sensor's sensitivity and durability are enhanced by encapsulating it in polydimethylsiloxane (PDMS). Additionally, a specially designed metal casing prevents OMCM from responding to pressure, thereby avoiding the challenge of multi-parameter demodulation and increasing its adaptability to harsh environments. The article analyzes the advantages of the new sensor structure and evaluates its performance in terms of temperature sensitivity and compressive strength through experimental tests. Finally, the article employs machine learning methods. Compared with traditional demodulation methods, the particle swarm optimization support vector regression (PSO-SVR) algorithm demonstrates a substantial reduction in demodulation error. Specifically, the mean absolute error (MAE) is reduced from 0.799 to 0.058, the mean absolute percentage error (MAPE) relative to the full scale decreases from 2.16% to 0.157%, and the root mean square error (RMSE) is diminished from 0.907 to 0.066. This article provides an effective solution for high-precision monitoring of ocean environmental temperature.

Efficient curvilinear optical proximity correction using non-uniform B-spline curves

Yanqiu Li, Yang he, Miao Yuan, Zhaoxuan Li, Weichen Huang, and Zhen Li

DOI: 10.1364/AO.537002 Received 18 Jul 2024; Accepted 07 Nov 2024; Posted 08 Nov 2024  View: PDF

Abstract: Curvilinear mask has received much attention in recent years due to its better lithography imaging fidelity than Manhattan mask. As a significant part of computational lithography techniques, the Curvilinear optical proximity correction (OPC) optimally designs the mask contour represented by parametric curves to generate a curvilinear mask structure. However, the current Curvilinear OPC process is computationally intensive and contains redundant data. In this paper, a Curvilinear OPC method using the non-uniform B-spline curve, together with a knot removal process, is proposed to improve the optimization efficiency and reduce the mask file size. The non-uniform B-spline curve is used to characterize curvilinear mask structure without complex splicing process, which can effectively reduce the computation complexity. To our best knowledge, knot removal theory is for the first time applied to solve the redundant data problem in Curvilinear OPC. Simulations and comparisons verify the superior optimization efficiency and data reduction (DRON) rate of the proposed method.

Control of surface edge roughness for aluminum alloy mirror based on sub-aperture polishing

Jiaqi Xie, Duo Li, Wensong Chai, Peng Ji, and Haitao Zhang

DOI: 10.1364/AO.539142 Received 12 Aug 2024; Accepted 07 Nov 2024; Posted 08 Nov 2024  View: PDF

Abstract: Current polishing methods are hard to guarantee the roughness uniformity between the edge and inner regions of the surface. Hence, this paper develops a sub-aperture polishing method based on chemical mechanical action to remove turning periodic marks and improve surface roughness uniformity. A compliant polishing pad with a rigid tool holder is proposed to ensure that the pressure in the contact area remains constant when the polishing tool moves out the edge of the workpiece. The optimal process parameters were investigated in the full aperture polishing experiment. Numerical simulation was implemented to analyze the relationship between overhang ratio and removal uniformity and optimize the polishing trajectory parameters. The polishing experiments of aluminum alloy mirrors reveal that the impurities inside the aluminum alloy restrict the further improvement of surface roughness. The average surface roughness is improved from 8.82 nm to 1.71 nm, and the peak and valley roughness value is reduced from 2.51 nm to 0.71 nm, which indicates the proposed sub-aperture polishing method can improve the surface roughness uniformity.

Enhancing Single Molecule Localization Microscopy with Deep Learning: A Novel Approach

Armin Abdehkakha, Seyyed Madani, and Craig Snoeyink

DOI: 10.1364/AO.539076 Received 12 Aug 2024; Accepted 06 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: Single-Molecule Localization Microscopy (SMLM) has significantly improved the visualization of sub-cellular structures, but enhancing the accuracy of 3D emitter localization remains challenging. The technique relies on precisely computationally localizing sparsely activated fluorophores, with traditional methods being iterative, time-consuming, and sensitive to camera noise and overlapping point spread functions (PSFs). We introduce a deep convolutional neural network that employs an innovative architecture to effectively manage diverse emitter scenarios, from isolated to densely packed. By transforming features from the real to the complex domain to integrate axial and lateral spatial information, our method outperforms existing deep learning-based localization algorithms. Tested on simulated SMLM frames with densities up to 2.0 μm², our approach demonstrates superior performance across varying emitter densities and signal-to-noise ratios, maintaining high accuracy even under challenging conditions.

Broadband optical antireflection metasurfaces design for F-P micro-optical accelerometers

ZeYu Yang, Wenyao Liu, ChenXi Liu, Wei Li, YanXia Gu, Haoyuan Tian, Yuxin He, Zhou Yanru, Enbo Xing, Lai Liu, Jun Tang, and Jun Liu

DOI: 10.1364/AO.538789 Received 27 Aug 2024; Accepted 06 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: Micro-optical accelerometers are highly sensitive, miniaturized, and integrateddevices that hold great promise. The sensitivity of the optical resonance cavity is closely relatedto the intensity of transmitted light. However, current methods for enhancing transmissionsuffer from limited bandwidth and low performance. Therefore, a novel metasurfaces basedsingle-layer all-dielectric antireflection structure is presented. The antireflective mechanism ofthe structure is shown by a quantitative relationship between the structural reflectance and thediffractive component. The metasurfaces designed based on the analytical results can realize abroadband antireflection range from 415 nm to 3200 nm. Additionally, the transmittance canreach up to 99.8% at the designed wavelengths. Finally, the sensitivity of the designed F-Pmicro-optical accelerometer can be enhanced three times compared to conventionalantireflection coatings. This provides new ideas for metasurfaces-based broadbandantireflection design and performance optimization of F-P micro-optical accelerometers.

Design of terahertz encoding metalens with adjustable focusing intensity

Caihe Lei, Bo Fang, Wentao Zhu, Haixiang Guo, Yuhan Xi, and Yue Li

DOI: 10.1364/AO.542013 Received 11 Sep 2024; Accepted 06 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: This paper presents a terahertz coded metalens with adjustable focusing efficiency. By integrating the phase change material GST-225 with the plasma metasurface and employing the transmission phase principle for phase modulation, flexible control of the single-focus focusing efficiency is achieved. Additionally, a dual-focus focusing metalens is devised. Leveraging the far-field scattering principle of the coded metasurface, the focal angle of the metalens can be adjusted, and it can be expanded to a dual-focus system through complex coding addition. In this system, by adjusting the crystallinity corresponding to different codes, the system can show different focusing efficiencies at each focus. The proposed dual-focus in this paper enables separate adjustment of focusing efficiency, offering a promising solution for on-chip and tunable devices in terahertz imaging and communication systems.

Observation of microwave enhancement effect based on Rydberg atomic vapor cell

Liting Zhang, ZHONGHAO Li, Shuai Liu, Shihong Xu, Jingxia Kong, Rui Zhao, Hao Guo, Huanfei Wen, Li Xin, Zongmin Ma, Jun Tang, and Jun Liu

DOI: 10.1364/AO.542721 Received 20 Sep 2024; Accepted 06 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: The atomic vapor cell plays a pivotal role in achieving high-precision measurements of microwave (MW) electric (E) fields for Rydberg atoms. This study examines the influence of the Fabry-Pérot (FP) effect on the precision of MW E-field measurements across atomic vapor cells of varying dimensions. Theoretical simulations and empirical validations are conducted for three vapor cells of different sizes. At a MW frequency of .904 GHz, the FP effect in the 10 mm cell is found to significantly enhances the MW E-field relative to larger cells (20 mm and 25 mm). Consequently, the minimum detectable sensitivity is increased by 1.63 times compared to the no-vapor-cell state. These findings contribute to the advancement of vapor cell design for quantum precision measurements and the development of future atomic MW communication technologies.

RBD-EVIO: Optimized Event-based Visual-Inertial Odometry for Large Field-of-View with Rotated Binary DART Descriptor

Yufan Zhang, Ze Wang, Hao Shi, Zhonghua Yi, Huang Haoyu, Yaozu Ye, and Kaiwei Wang

DOI: 10.1364/AO.539209 Received 14 Aug 2024; Accepted 05 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: Event-based cameras offer unique advantages over traditional cameras, such as high dynamic range, absence of motion blur, and microsecond-level latency. This paper introduces an innovative approach to visual odometry by integrating the newly proposed Rotated Binary DART (RBD) descriptor within a Visual-Inertial Navigation System (VINS)-based event visual odometry framework. Our method leverages event optical flow and RBD for precise feature selection and matching, ensuring robust performance in dynamic environments. We further validate the effectiveness of RBD in scenarios captured by a large field-of-view fisheye event camera under high dynamic range and high-speed rotation conditions. Our results demonstrate significant improvements in tracking accuracy and robustness, setting a new benchmark for event-based visual odometry. This work paves the way for advanced applications in high-speed, high dynamic range and large Field-of-View (FoV) visual sensing.

Simulation study on supercontinuum broadening based on BIC model

JingJing Zhang, Wenjie Sun, runyu He, XIAOXIAN SONG, ZiJie Dai, Yang Liu, Dong Pan, Di Wu, Yanan Wang, zhongkun gao, Chenshui Guan, Kai Guo, and Huan Chen

DOI: 10.1364/AO.541864 Received 10 Sep 2024; Accepted 05 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: Bound states in the continuum (BICs) refer to waves that are entirely confined within the continuous spectrum of radiation waves without interacting with them. In our study, we attempted to construct a waveguide satisfying BIC conditions by forming a polymer layer on a 4H-SiC substrate, positioned on an SiO\textsubscript{\textsubscript{2}} insulator. By fine-tuning the waveguide parameters, we minimized losses to the substrate continuum and determined that the lowest loss meeting BIC conditions occurs when the HSQ width is 1.82\si{\micro\metre} and the 4H-SiC thickness is 440\si{\nano\meter}. Subsequently, we investigated the supercontinuum generation (SCG) in this waveguide. First, we analyzed the primary linear and nonlinear effects in the SCG process, introducing well-established theoretical frameworks such as the generalized nonlinear Schrödinger equation (GNLSE) for pulse propagation in nonlinear media. We then studied the influence of waveguide parameters on SCG, observing the variations in SCG with different HSQ widths and 4H-SiC thicknesses. Our results indicate that optimal spectral broadening and conversion efficiency are achieved with an HSQ width of 1.82\si{\micro\metre} and a 4H-SiC thickness of 440\si{\nano\meter}. In our simulations, the waveguide length was set to 1 cm, and the pump pulse was modeled as a Gaussian pulse with a width of 100 fs and a peak power of 8W.

Three-Point Supported 2-DOF Large-Area Tilting Mirror Inspired by a Playground Facility

Ming-Te Chiang, Ming-Hsuan Tsai, Guan-Yang Liu, and Jui-che Tsai

DOI: 10.1364/AO.542526 Received 19 Sep 2024; Accepted 05 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: In this paper, we demonstrate a three-point-supported 2D optical scanner designed to enhance the Field of View (FoV), optical scanning angles, and facilitate the development of large mirrors (>10 cm). By integrating Fused Deposition Modeling (FDM) 3D printing with electromagnetic driving, we present a cost-effective, large-size scanning mirror with two-dimensional scanning capabilities. The mirror has an area of 144 cm², enabling greater light capture for enhanced scanning performance. Under DC driving, the maximum optical scanning angles are 5.99° in the x-direction and 12.61° in the y-direction. For AC driving, the resonant scanning frequencies are 18.2 Hz for the x-scan and 19 Hz for the y-scan, with maximum scanning angles of 7.87° for the x-scan and 7.19° for the y-scan.

Optoelectronic Oscillator Using Visible LEDs and Plastic Optical Fibers

Vitor Ferreira, Vanessa Magri, Alexandre Santos, and Ricardo Ribeiro

DOI: 10.1364/AO.542580 Received 02 Oct 2024; Accepted 05 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: This Note describes an optoelectronic oscillator (OEO) capable of accepting CW light as input and providing radio-frequency (RF) carriers as output. To the best of our knowledge, we are the first describe an easy-to-assemble and low-cost OEO that uses visible LED sources with a standard 1 mm diameter plastic optical fiber as part of the oscillation ring. The gain is solely provided by a transimpedance pre-amplifier integrated with a photodetector. Self-oscillations occurred. Fundamental frequencies in the 7.7 - 26.5 MHz range was generated, since the length of the fiber and the bias current feeding the LED are both correctly tuned. A comprehensive approach is used to explain the operation of the OEO. The proposed OEO may be didactically useful for use in research or teaching laboratories by untrained people.

Short-range azimuth measurement method based on single-pulse laser beam expanding mechanism

lin gan and He Zhang

DOI: 10.1364/AO.541686 Received 10 Sep 2024; Accepted 05 Nov 2024; Posted 08 Nov 2024  View: PDF

Abstract: Aiming at the problem of azimuth measurement of short range target with pulsed laser, a new azimuthmeasurement method based on single pulse laser beam expanding mechanism is proposed based on theresearch of pulse laser dynamic/static azimuth detection method. The echo power equation of single-pulselaser beam expanding short-range detection is derived theoretically. Combined with the spatial geometricdistribution of optical path and the normalized sum-difference angle measurement algorithm of four-quadrantdetector, a single-pulse laser short-range azimuth angle calculation model is established. Monte Carlotheoretical simulation and laboratory static measurement experiments are carried out. The influencemechanism of laser emission power, beam expanding reflection cone angle and target projection size on theprobability distribution of azimuth measurement is studied. The results show that with the increase oftransmission power and target projection size, the half width of azimuth measurement distribution decreases,the peak value increases, and the detection accuracy improves. With the increase of the cone angle of thereflected light, the half width of the azimuth measurement distribution increases, the peak value decreases,and the detection accuracy decreases. As the spot is far away from the coordinate center, it will lead to anincrease in the half width of the azimuth measurement probability distribution, a decrease in the peak value,and a decrease in the detection accuracy.

Method of calculation of paraxial design parameters of hybrid catadioptric zoom system with focus tunable elements

Antonin Miks and Jiri Novak

DOI: 10.1364/AO.542110 Received 12 Sep 2024; Accepted 05 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: This paper introduces and analyses a theory for a paraxial design of a hybrid catadioptric optical system with variable focal length, which uses focus tunable optical components. Compared to the conventional zoom lens system, the proposed hybrid optical system can be designed with a smaller length and weight than a lens system of similar characteristics. The hybrid system does not need the movement of individual elements for zooming. All necessary relations for the calculation of the paraxial parameters and the third-order spherical aberration of the hybrid optical system are derived. The presented theory helps to find out optical powers distribution of individual optical elements of the whole hybrid zoom system considering the requirement on the spherical aberration of the system. In addition, the procedure for the calculation of basic design parameters of such an optical system is shown by examples.

Optical characterization of a manual tunable lens for eye care applications

Raquel Salvador-Roger, Jose Esteve-Taboada, and Vicente Mico

DOI: 10.1364/AO.535164 Received 09 Jul 2024; Accepted 05 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: Focus tunable lenses have increased their popularity worthwhile for the last decade. In this study we present an experimental optical characterization of a commercially available manually tunable lens to describe its behavior regarding optical aberrations, expressed in terms of Zernike coefficients, under different laboratory conditions. Measurements were performed by using a Shack-Hartmann aberrometer and four different experiments were carried out in order to assess: (1) the lens stability in time for a given temperature, (2) the temporal response of the lens, (3) the behavior of the lens when changing the room temperature, and (4) the possible influence of gravity on the lens performance according to its mounting orientation. The main conclusion we outlined states that the properties of the tunable lens stay steady over time as long as room temperature remains constant, making it a good option for ophthalmologic and optometric eye care applications.

NbSe2/PtTe2 heterostructures as saturable absorbers for mid-infrared pulsed solid-state lasers

Yiheng Yang, Lulu Gao, Yingxue Han, Qiong Gao, ruijun lan, and yingjie shen

DOI: 10.1364/AO.538546 Received 05 Aug 2024; Accepted 05 Nov 2024; Posted 07 Nov 2024  View: PDF

Abstract: We have realized for the first time a 2 μm nanosecond solid-state passive Q-switched Tm:YAP laser based on a NbSe2/PtTe2 heterojunction saturable absorber. At a incident pump power of 12.69 W, the Tm:YAP laser produces stable laser pulses with a minimum pulse width of 818 ns, a maximum single pulse energy of 15.48 μJ, and a peak power of 18.93 W at a repetition rate of 79.44 kHz. The comparison results show enhanced saturable absorption performance compared to single NbSe2 (1 μs, 70.32 kHz) and single PtTe2 (1.31 μs, 71.97 kHz). The experimental results confirm that the NbSe2/PtTe2 heterojunction is a promising saturable absorption material that can be used to realize high-performance mid-infrared pulsed lasers. The resulting nanosecond 2 μm Q-switched pulsed laser will play an important role in atmospheric monitoring, lidar, and other fields, and can provide a strong driving force.

Design requirements of a Spectropolarimeter for solar Extreme-ultraviolet Observations and characterization of K-mirror based on Brewster’s angle

Raveena Khan, Radhika Dharmadhikari, Harsh Mathur, Nagaraju Krishnappa, Sinchana R. Jain, D. V. S. Phanindra, and Kolandaiswamy Sagayanathan

DOI: 10.1364/AO.537460 Received 23 Jul 2024; Accepted 04 Nov 2024; Posted 05 Nov 2024  View: PDF

Abstract: Measuring the linear polarization signal in extremeultraviolet (EUV) spectral lines, produced by the Hanleeffect, offers a promising technique for studying magnetic fields in the solar corona. The required signal-tonoise ratio for detecting the Hanle polarization signalsis in the order of 101(off-limb) to 106(disk centre). Measuring such low signals in the photon starved observations demands for highly efficient instruments. In thispaper, we present the design of an instrument, SpectroPOLarimeter for Extreme-ultraviolet Observations(SPOLEO), which utilizes reflective components withsuitable mirror coatings and thicknesses to minimizethe throughput losses. We analyze the system performance within the spectral range from 740 to 800 Å. TheK-mirror based polarimeter model provides a polarizingpower of 20 – 40% in this wavelength range. Based onthe system throughput and polarizing power, we discussabout various possibilities for achieving the requiredsignal-to-noise ratio, along with their limitations. Dueto lack of facilities for fabrication and testing in theEUV, we have calibrated a prototype of the reflectionbased polarimeter setup in the laboratory at the visiblewavelength of 700 nm.

Nonlinear techniques for few-mode wavefront sensors

Jonathan Lin and Michael Fitzgerald

DOI: 10.1364/AO.537925 Received 31 Jul 2024; Accepted 04 Nov 2024; Posted 05 Nov 2024  View: PDF

Abstract: We present several nonlinear wavefront sensing techniques for few-mode sensors, all of which are empirically calibrated and agnostic to the choice of wavefront sensor. The first class of techniques involves a straightforward extension of the linear phase retrieval scheme to higher order; the resulting Taylor polynomial can then be solved using the method of successive approximations, though we discuss alternate methods such as homotopy continuation. In the second class of techniques, a model of the WFS intensity response is created using radial basis function interpolation. We consider both forward models, which map phase to intensity and can be solved with nonlinear least-squares methods such as the Levenberg-Marquardt algorithm, as well as backwards models which directly map intensity to phase and do not require a solver. We provide demonstrations for both types of techniques in simulation using a quad-cell sensor and a photonic lantern wavefront sensor as examples. Next, we demonstrate how the nonlinearity of an arbitrary sensor may studied using the method of numerical continuation, and apply this technique both to the quad-cell sensor and a photonic lantern sensor. Finally, we briefly consider the extension of nonlinear techniques to polychromatic sensors.

Cryptoanalysis of multiple-image encryption scheme based on amplitude- and phase-truncation in the Fourier domain

YI XIONG, Jiashuai Liu, Jiao Gu, and Ravi Kumar

DOI: 10.1364/AO.540688 Received 30 Aug 2024; Accepted 04 Nov 2024; Posted 05 Nov 2024  View: PDF

Abstract: This paper presents a comprehensive cryptoanalysis of a multiple-image encryption scheme based on amplitude truncation (AT) and phase truncation (PT) in the Fourier domain. In contrast to the conventional single-image cryptosystem based on phase-truncated Fourier transform (PTFT), the enhanced PTFT-based cryptosystem was proposed to encode multiple images efficiently and to augment the security strength by expanding the key space. Nevertheless, we found that the amplitude key exhibits low sensitivity, which has a restricted impact on the security enhancement and makes the scheme vulnerable. Moreover, the two random phase masks (RPMs) employed as private keys are uncorrelated with the plaintexts, which can be recovered through a devised known-plaintext attack (KPA). Once these additional private keys are recovered, the number of unknown keys is reduced to two, making it possible to recover plaintext information encrypted by this advanced PTFT-based cryptosystem using an iterative attack without any knowledge of the private keys. Based on these findings, a hybrid attack consisting of two cascaded KPAs and chosen-ciphertext attacks (CCAs) is proposed to successfully crack the improved PTFT-based cryptosystem. Numerical simulations have been performed to validate the feasibility and effectiveness of the proposed hybrid attack.

Optical performance analysis of hybrid parabolic-trough collector with photovoltaic slats

Marta Leal Rueda, Ramon Pujol, José Domingo Álvarez, María del Mar Castilla Nieto, José Luis Torres Moreno, Gabriel Cardona, and Manuel Pérez García

DOI: 10.1364/AO.537784 Received 30 Jul 2024; Accepted 31 Oct 2024; Posted 31 Oct 2024  View: PDF

Abstract: Small-sized parabolic trough collectors are a promising solution for renewable heat supply, meeting the industrial demand for thermal energy up to 250 ºC. In this manuscript, a novel optical design hybridizing parabolic trough concentrators with photovoltaic generators is introduced, incorporating actionable photovoltaic slats in the aperture plane. This configuration allows efficient operation under diffuse irradiance and improves electricity production when direct irradiation is insufficient. Optical simulations using OTSunWebApp software demonstrate that the inclusion of photovoltaic slats does not significantly reduce optical efficiency. The hybrid collector allows simultaneous or exclusive production of thermal and photovoltaic energy, adapting to various energy demand conditions.

A dual-band transmittance Defogging Model

Jin Duan, Peiren Guo, Suxin Mo, jialin wang, and Xu Yang

DOI: 10.1364/AO.534959 Received 05 Jul 2024; Accepted 31 Oct 2024; Posted 31 Oct 2024  View: PDF

Abstract: In image defogging, visible images preserve color and detail well, while shortwave infrared(SWIR), due to its longer wavelength and less scattering, has a much higher penetration ability than visible. Researchers typically combine the characteristics of both to perform fused image defogging.However, In some dense fog scenes, the defogging effect of SWIR and visible fusion images is not significant.When further using the atmospheric scattering model for defogging, this model has a key a priori assumption: ’the transmittance in the visible light band is assumed to be a constant value.’ The limitation of this assumption does not apply to multi-band fusion images with significant variations in transmittance. Addressing the issue of the model’s inapplicability, this paper proposes a dual-band defogging model. First, fusion weights are calculated based on gradient and saturation to generate the fusion image. Subsequently, we calculate the transmittance for each band separately and combine it with the fusion weights to generate the overall weighted transmittance. Compared to the atmospheric scattering model that generates transmittance from fusion images, the transmittance map generated by this method can better display details in hazy areas and perform well when processing the foreground. Researchers experimentally test three algorithms that utilize single-band transmittance models and five algorithms for the fusion of SWIR and visible light, proving the effectiveness of the proposed model in subjective visual and objective evaluation metrics.

High-frequency Structure Deformation Measurement Based on an Event Camera

Yife Bian, Guan Banglei, Zibin Liu, Ang Su, Shiyao Zhu, Yang Shang, and Qifeng Yu

DOI: 10.1364/AO.538471 Received 07 Aug 2024; Accepted 31 Oct 2024; Posted 01 Nov 2024  View: PDF

Abstract: Large-scale structures suffer high-frequency deformations due to complex loads. However, measurement methods based on traditional high-speed cameras are limited by challenging lighting conditions and high equipment costs. This paper proposes a method to measure high-frequency deformations exploiting an event camera and LED markers. Firstly, observation noise is filtered based on the characteristics of the event stream generated by LED markers blinking and spatiotemporal correlation. Then, LED markers are extracted from the event stream after differentiating between motion-induced events and events from LED blinking, which enables extracting high-speed moving LED markers. Ultimately, high-frequency planar deformations are measured by a monocular event camera. Experimental results confirm the accuracy of our method in measuring high-frequency planar deformations.

Inversion for offshore Oil-water Emulsions Concentration Based on a Six-Flux Model of Laser-Induced Fluorescence

Xiaodan Zhang, Zhenxue He, Fangfang Liang, Jie Dong, Kui Yu, Beibei Xie, and Hu Hao

DOI: 10.1364/AO.534964 Received 08 Jul 2024; Accepted 30 Oct 2024; Posted 13 Nov 2024  View: PDF

Abstract: Oil-water emulsions, as one of the momentous weathering forms of the marine oil-spill, have caused more severedetriment to the marine environment. Laser-induced fluorescence (LIF) is an extremely influential technique for monitoringspilled oil at sea. However, the evaluation of offshore oil-water emulsions concentration based on LIF detection technologyhas been rarely discussed. Simultaneously, a scientific low-flux model including fluorescence flux has not been establishedand applied to detect oil spill at sea. In view of this, a six-flux model of laser-induced fluorescence is proposed to invert theconcentration of oil-water emulsions at sea. On the cornerstone of laser flux, fluorescence flux is introduced. And utilizing theabsorption, scattering and other characteristics of flux in the medium, differential equations of various flux are established,and the solution framework of the differential equations are afforded. Thereafter a formula of fluorescence radiation transferfactor of the oil-water emulsions and their concentration is derived. Furthermore, the validity and availability of the proposedmodel are proved by experiments. The experimental results reveal that the proposed model has high accuracy in inverting theconcentrations for oil-water emulsions, and the average error is both within 6%. Meanwhile, this model consumes a short time,not exceeding 60 s at most. Utilizing the model, the concentration of oil-water emulsions can be evaluated in real time.

Improving Data Sampling with Rapid Statistical Convergence in Digital Fourier Microscopy Analysis

Angel Zuccolotto-Bernez, Luis Rojas-Ochoa, Stefan Egelhaaf, and Manuel Escobedo Sanchez

DOI: 10.1364/AO.537840 Received 29 Jul 2024; Accepted 28 Oct 2024; Posted 01 Nov 2024  View: PDF

Abstract: Soft matter research often involves studying correlation functions, such as the intermediate scattering function. Wave scattering experiments or Digital Fouriermicroscopy are usually used to obtain this function, generating large amounts of data that must be analyzedto obtain reliable information. However, this processcan be time-consuming and requires an optimized dataanalysis procedure to minimize calculations while ensuring statistical validity. To address this issue, we havedeveloped an algorithm that uses an efficient samplingtechnique to reduce the number of calculations neededfor fast statistical convergence in Digital Fourier Microscopy. Our algorithm provides information equivalent to traditional analysis but in a much shorter timeframe, up to two orders of magnitude faster.

Design and fabrication of a grism placed at the end face of an optical fiber for coupling light into a waveguide

Piotr Pala, Katarzyna Komorowska, Andrea Szpecht, and Tadeusz Martynkien

DOI: 10.1364/AO.540040 Received 21 Aug 2024; Accepted 16 Oct 2024; Posted 16 Oct 2024  View: PDF

Abstract: In this study, we designed, fabricated, and experimentally tested grating-prism (grism) structures placed at the end face of an optical fiber to couple light into waveguides. We proposed a simple and fast numerical computational approach based on the search conditions of guided-mode resonance to optimize the coupler geometry. Finally, we used the low-cost, repeatable, and accurate nanoimprint method to fabricate an optical fiber end-face grism, which enables the coupling of light into SU-8 waveguides. Moreover, the fabricated fiber coupler was used to estimate waveguide losses.