Technology of Cavity Fabrication for Whispering Gallery Modes Laser ( $$\lambda \sim 3\mbox{ \textendash }4\,\mu $$ m)

Abstract

Different wet-etching solutions based on CrO 3; HClO 4 and HBr for materials lattice-matched to InAs for whispering gallery modes (WGM) lasers (3–4 μm) disk cavities fabrication were studied. In the case of WGM-laser cavity – it is crucial to have vertical and smooth sidewalls, free from roughness and other irregularities. Perfect circular disk cavities with diameter from 50 to 300 μm were obtained by using HBr-based wet-etching technology. At a total cavity height reaching 30 μm, the vertical part of the sidewalls was about 10 μm. Based on the obtained disk cavities, WGM lasers are created that produce coherent radiation with a wavelength of \(\lambda \approx (3.0\mbox{ \textendash }3.5)\) μm in a continuous regime at 77 K and in a pulsed regime up to 125 K.