Optically Pumped Continuously Tunable Mid-IR Distributed-Feedback Semiconductor Laser

Abstract

An 80-nm continuous, mode-hop-free, wavelength tuning range centered at $3.1~\mu \text{m}$ has been demonstrated for a large area, optically pumped mid-infrared type-II semiconductor distributed feedback (DFB) laser with a spectral linewidth of 1.2 nm at $2.5\times $ threshold and 820 mW single-facet output power operated CW at 80 K, suitable for atmospheric pressure molecular spectroscopy and remote sensing. Wavelength tuning of this DFB laser is achieved by translating the optical pump stripe across the device patterned with a hyperbolically chirped, location-dependent-period grating. The impact of chirp along the gain stripe is clarified and optimized to allow continuous tuning.