Single-mode 2.4 μm InGaAsSb/AlGaAsSb distributed feedback lasers for gas sensing

Single-mode laser diodes on GaSb substrates were developed using InGaAsSb/AlGaAsSb triple quantum well active regions grown by molecular beam epitaxy. The devices were fabricated using lateral Cr gratings, with a grating pitch designed to coincide with a strong absorption feature of HF gas, deposited adjacent to a dry-etched narrow ridge waveguide. High sidemode suppression was achieved, and in 20 °C continuous-wave operation, devices with a 400 μm long cavity provided 9 mW total output power at the 2396 nm target wavelength. High-resolution direct absorption measurements of HF gas agreed with HiTran calculations, yielding an absorption linewidth of 0.030 nm.