Room temperature continuous wave interband cascade lasers for gas sensing

Abstract

The wavelength range from 3 μm to 4 μm is of special interest for gas-sensing applications. We present systematic design optimizations of interband cascade laser (ICL) layers to reduce the dissipated threshold power at room temperature with the aim to facilitate high performance room temperature operation in this wavelength range. Furthermore, we show that slight variations of the active region design enable us to easily obtain emission in this target wavelength range and beyond. Based on the epitaxial material grown, ridge waveguide lasers and distributed feedback interband cascade lasers with vertical sidewall gratings are fabricated. We obtain single mode emitting devices operating in continuous wave mode at room temperature. The devices exhibit side mode suppression ratios up to ~25 dB and typical fine tuning rates of 0.09 nm/mA and 0.3 nm/K. Therewith, the presented devices are ideally suitable for highly sensitive gas sensing of hydrocarbons.