Figure-of-merit analysis of distributed sidewall loss method to suppress high-order modes in broad area quantum cascade lasers

Ron Kaspi,Matthew Suttinger

doi:10.1063/5.0016127

Abstract

We have modeled broad-area ridge-waveguide quantum cascade lasers (QCLs) using COMSOL and generated a rank-ordering of high-order transverse lateral modes as a function of cavity width on the basis of a figure-of-merit. In particular, we corroborate experimental results previously obtained using the distributed sidewall loss (DSL) method to suppress high-order transverse lateral modes and extract fundamental mode in broad-area QCLs. COMSOL modeling shows that waveguide losses preferentially incurred by the high-order modes, due to the direct sidewall contact with metal as prescribed by the DSL method, can be used to obtain single-lobed emission with enhanced brightness in broad-area QCLs.

Highlights

Several mode control strategies have been recently developed, with varying success, which either provide additional losses to highorder modes or reduce the optical confinement of high-order modes scitation.org/journal/adv to favor fundamental mode operation in broad area quantum cascade lasers (QCLs)
We have recently introduced and experimentally demonstrated the concept of the “distributed sidewall loss” (DSL) in broad area QCLs as a way to suppress high-order modes to obtain fundamental transverse mode operation when it would not otherwise be favored
Because the added losses are incurred preferentially by high-order modes with wave-functions that penetrate these boundaries to a larger extent, mode selection can be strongly altered in favor of the fundamental mode

Summary

Introduction

Several mode control strategies have been recently developed, with varying success, which either provide additional losses to highorder modes or reduce the optical confinement of high-order modes scitation.org/journal/adv to favor fundamental mode operation in broad area QCLs.

Objectives

Results

Conclusion