Continuous-wave operation of distributed feedback interband cascade lasers

Continuous-wave distributed feedback interband cascade lasers operating near 3.3 μm are reported. Single longitudinal mode emission is achieved with side mode suppression ratio greater than 30 dB at temperatures up to 175 K. A clear Bragg stop band in the laser emission spectrum indicates a dominant index coupling with the first-order grating. Detailed characteristics of these lasers are discussed.