Interband cascade distributed-feedback lasers

Significant recent advances in the high-temperature, high-power performance of type-II antimonide interband cascade lasers (ICLs) operating in the mid-infrared are reported. A 5-stage ICL with a 12-mu m ridge width and Au electroplating for improved epitaxial-side-up heat sinking operates cw to a maximum temperature of 257 K, where the emission wavelength is 3.7 mu m. A similar device with a ridge width of 22 mu m emits > 260 mW per facet for cw operation at 80 K (lambda = 3.4 mu m) and 100 mW at 200 K (lambda = 3.6 mu m). Beam qualities for the narrowest ridges approach the diffraction limit. A single-mode output power of 41 mW has been obtained at T = 120 K and lambda approximate to 3.44 pm from a 13-mu m-wide ICL patterned with a Ge distributed-feedback grating. The side mode suppression ratio at the maximum power is 23 dB, and the linewidth of 0.1 nm is instrument-limited. An alternate contacting geometry yielded robust single-mode output over a broad range of currents and temperatures, and current tuning of the wavelength by up to 17 nm.