Surface emitting quantum-cascade lasers with a second-order grating and increased coupling coefficient

Abstract

The results of studying the characteristics of surface-emitting quantum-cascade ring lasers with a second-order grating are presented. The selection of etching receipt by ion beam lithography made it possible to increase the coupling coefficient to 12 cm–1. Lasing close to 7.6 μm with a low threshold current density (about 0.3 kA/cm2) is demonstrated.