Nonlinear optical materials with large nonlinear optical response in the long-wavelength infrared (LWIR, 8-14 µm) spectral range are highly required for versatile applications in fundamental science, medicine, biology, material processing and environmental monitoring. However, standard nonlinear optical materials in this regime are limited by a narrow transparency region and/or a weak nonlinear optical response.

Among optical materials, tellurium (Te) stands out as an elemental narrow-gap semiconductor and topological material possessing an ultrawide infrared transparency region (4-32 µm), as well as unusual electrical and magnetic properties. In addition, Te possesses extremely large second order optical nonlinearity in the LWIR region. However, the third-order optical nonlinearity of bulk Te in this region had not been explored so far.

In this paper, the authors have experimentally characterized the nonresonant nonlinear optical response of bulk Te with a 10 µm-wavelength femtosecond laser. The Kerr nonlinearity is found to be nearly 100 times larger than that of GaAs in the E⊥c orientation. In addition, the multiphoton absorption has been observed at intensities > 1 GW/cm². The strong nonlinear optical response, in addition to unique electrical and magnetic properties, makes Te an intriguing material for mid- and long-wavelength infrared nonlinear photonics.

---

---

 Add Comment

You must log in to add comments.