Far Field of Bragg Reflection Waveguides: Characteristics and Closed-Form Approximation

A comprehensive study of the far-field diffraction pattern of Bragg reflection waveguides is presented. Using a Gaussian approximation of the near-field profile, an analytical formula for the far-field pattern of the fundamental Bragg mode is obtained. The proposed closed-form representation offers a powerful technique for examining the far-field characteristics, which provides insight into the design optimization of Bragg reflection waveguides.