Study of Propagating Modes and Reflectivity in Bragg Filters with AlxGa1-xN/GaN Material Composition

TL;DR

This paper analytically investigates propagating waves and reflectivity in AlxGa1-xN/GaN-based Bragg filters, highlighting how grating length and coupling influence photonic bandgap properties for optical communication applications.

Contribution

It introduces an analytical model for AlxGa1-xN/GaN Bragg filters considering material composition effects on wave propagation and reflectivity, aiding design optimization for specific wavelengths.

Findings

Increased grating length enhances electromagnetic wave reflection.

Strong coupling broadens the photonic bandgap.

Optimal grating and coupling parameters enable bandgap tuning at 1550 nm.

Abstract

In this paper, forward and backward propagating waves and reflectivity in an optical waveguide structure namely the fiber Bragg reflector also considered as a one dimensional photonic crystal, are analytically computed using coupled mode theory for different grating lengths and coupling conditions. AlxGa1-xN/GaN material composition is considered as unit block of the periodic organization, and refractive index of AlxGa1-xN is taken to be dependent on material composition, bandgap and operating wavelength following Adachis' model. The structure being considered is the Bragg grating where increase in grating length enhances the reflection of electromagnetic wave, and strong coupling provides larger bandgap spectral width. Input wavelength is made different from Bragg wavelength to study the characteristics of propagating waves. A suitable combination of grating length and coupling coefficient is helpful in designing the photonic bandgap at 1550 nm wavelength. These characteristic curves can be utilized to study how waves propagate through the optical waveguides which have a special place in optical communications