Impact of slow-light enhancement on optical propagation in active semiconductor photonic crystal waveguides

TL;DR

This paper develops and validates coupled Bloch wave equations to analyze how slow-light effects in active semiconductor photonic crystal waveguides enhance optical gain and influence reflection and transmission properties.

Contribution

It introduces a coupled wave analysis for active photonic crystal waveguides and compares it with numerical methods, highlighting effects of material gain on waveguide behavior.

Findings

Coupled Bloch wave equations accurately model slow-light enhancement effects.

Material gain induces backscattering and reflection at interfaces.

High gain levels perturb the waveguide band structure.

Abstract

We derive and validate a set of coupled Bloch wave equations for analyzing the reflection and transmission properties of active semiconductor photonic crystal waveguides. In such devices, slow-light propagation can be used to enhance the material gain per unit length, enabling, for example, the realization of short optical amplifiers compatible with photonic integration. The coupled wave analysis is compared to numerical approaches based on the Fourier modal method and a frequency domain finite element technique. The presence of material gain leads to the build-up of a backscattered field, which is interpreted as distributed feedback effects or reflection at passive-active interfaces, depending on the approach taken. For very large material gain values, the band structure of the waveguide is perturbed, and deviations from the simple coupled Bloch wave model are found.