Study on a DFB Laser Diode Based on Sampled Grating Technique for Suppression of the Zeroth Order Resonance

Abstract

A distributed feedback (DFB) semiconductor laser based on sampled grating with multiple sections, i.e., a straight, a bent, and a tilted waveguide, is proposed to suppress the $0{\rm{th}}$ -order resonance. A sampling structure with nonlinear equivalent chirp pattern is carefully designed to compensate the basic grating chirp introduced by the bent and tilted waveguide. The facet reflection can also be reduced due to the tilted waveguide to avoid the influence of random facet phase. As a result, good single longitudinal mode (SLM) property and high wavelength accuracy in the $ - 1{\rm{st}}$ -order subgrating is achieved, even with a large sampling period. Because the lasing wavelength can be easily adjusted by a sampling period and the fabrication accuracy requirement is relaxed, it will benefit the realization of low-cost DFB laser arrays with a good SLM property and accurate lasing wavelength.