Fiber Bragg Grating Reflection Spectrum Simulation

A Fiber Bragg Grating (FBG) is a reflective grating commonly used in optical sensors. It generates interference patterns of reflected waves through periodic refractive index modifications within the optical fiber, enabling precise light measurements. The reflection spectrum of an FBG provides substantial information about grating parameters including refractive index, length, and temperature. Simulating FBG reflection spectra in MATLAB requires two key code implementations:

1. Generating the refractive index distribution of the grating, which involves defining parameters such as periodicity and modulation amplitude. This typically utilizes MATLAB's array operations to create periodic refractive index profiles using sinusoidal or square wave functions, with parameters controlling grating length and apodization.

2. Calculating the reflection spectrum across specified wavelength ranges and resolutions. This implementation commonly employs transfer matrix methods or coupled-mode theory algorithms, where wavelength scanning loops compute reflection coefficients at each wavelength point using matrix multiplication operations for multilayer interference calculations.

These operations can be efficiently performed using MATLAB's Fiber Bragg Grating Simulation Toolbox, which provides comprehensive functions and utilities for convenient FBG simulation and analysis. The toolbox includes specialized functions like fbg_reflectivity() for spectrum calculation and grating_profile() for index modulation generation. Understanding FBG reflection spectra and their MATLAB simulation methodology is therefore essential for optical sensor development and characterization.