Corrugated-sidewall interband cascade lasers with single-mode midwave-infrared emission at room temperature

Abstract

We report interband cascade lasers operating in a single spectral mode (λ≈3.6 μm) at −5–30 °C. A corrugated pattern etched into both sidewalls of the 6- and 9-μm-wide ridges serves to suppress higher-order lateral modes by increasing their loss, and also provides a fourth-order distributed-feedback grating for longitudinal mode selection. Despite the grating’s weak coupling strength, the 9 μm ridge produced up to 12 mW per facet of single-mode cw output power at 25 °C, with a side-mode suppression ratio of >30 dB.