High power GaSb-based distributed feedback laser with laterally coupled dielectric gratings at 1.95{\mu}m

TL;DR

This paper presents a novel lateral dielectric grating design for GaSb-based DFB lasers, achieving high power, stable single-mode operation, and broad tunability, overcoming fabrication challenges of traditional gratings.

Contribution

Introduction of a lateral coupled dielectric grating structure for GaSb lasers, simplifying fabrication and improving performance over traditional buried or metal gratings.

Findings

Achieved 47.02 mW continuous-wave output power at room temperature.

Demonstrated stable single-mode operation from 300-1000 mA.

Maximum side mode suppression ratio of 46.7 dB.

Abstract

Traditional Distributed Feedback (DFB) or Distributed Bragg Reflector (DBR) lasers typically utilize buried gratings as frequency-selective optical feedback mechanisms. However, the fabrication of such gratings often necessitates regrowth processes, which can pose technical challenges for materials platforms such as GaAs and GaSb. Metal gratings were also used for GaSb lasers but they introduce additional absorption loss that limits device efficiency and output power. In this paper, we introduce a novel laterally coupled dielectric Bragg grating structure, which enables highly controllable, deterministic, and stable coupling between the grating and the optical mode. Our device demonstrates a continuous-wave output power of 47.02 mW at room temperature, exhibiting stable single-mode operation from 300-1000 mA and achieving a maximum side mode suppression ratio of 46.7 dB. These results underscore the innovative lateral coupled dielectric grating as a feasible and technologically superior approach for fabricating DFB and DBR lasers, which hold universal applicability across different material platforms and wavelength bands.