Refractive index change of Fiber Bragg Gratings (FBGs). 1) a uniform positive-only refractive index change, where the refractive index change has a fixed amplitude. 2) a Gaussian-apodized positive only index change, where the refractive index change is graded to give improved side lobe suppression while maintaining a strong reflectance. 3) a raise-cosine-apodized zero-dc refractive index change, again with a graded index change. 4) a discrete phase shift refractive index change, with a phase shift of ${\displaystyle \pi }$.

This diagram image could be re-created using vector graphics as an SVG file. This has several advantages; see Commons:Media for cleanup for more information. If an SVG form of this image is available, please upload it and afterwards replace this template with {{vector version available|new image name}}. It is recommended to name the SVG file “Fbg4.svg”—then the template Vector version available (or Vva) does not need the new image name parameter.

Uploader drew the image

I, the copyright holder of this work, hereby publish it under the following license:

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue

	This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
	You are free: to share – to copy, distribute and transmit the work to remix – to adapt the work Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
	This licensing tag was added to this file as part of the GFDL licensing update.http://creativecommons.org/licenses/by-sa/3.0/CC BY-SA 3.0Creative Commons Attribution-Share Alike 3.0truetrue