Room temperature operation of ultra-short quantum cascade lasers with deeply etched Bragg mirrors

Mid-infrared GaAs based bound-to-continuum quantum cascade microlasers with ridge waveguide geometry are fabricated by the monolithic integration of deeply etched semiconductor-air Bragg mirrors. Devices with ultra-short cavities of 50 and 150 µm can be operated near room temperature (260 K) or at room temperature (300 K), respectively. 50 µm-long devices show singlemode emission up to relatively high drive currents due to the large mode spacing of about 30 cm−1 (340 nm).