Single-mode high-power interband cascade lasers for mid-infrared absorption spectroscopy

For high-sensitivity absorption spectroscopy, single-mode light sources capable of emitting high optical output power in the 3 to 5 mu m wavelength range are vital. Here, we report on interband cascade lasers that emit 20 mW of optical power in a single spectral mode at room temperature and up to 40 mW at 0 degrees C using second-order laterally coupled Bragg gratings for distributed feedback. The lasers employ a double-ridge design with a narrow 3-mu m-wide top ridge to confine the optical mode and a 9-mu m-wide ridge for current confinement. The lasers were developed for an integrated cavity output spectroscopy instrument for stratospheric detection of hydrogen chloride at a wavelength of 3.3746 mu m and emit at the target wavelength with more than 34 mW of single-mode power. (C) 2015 Optical Society of America