High average power first-order distributed feedback quantum cascade lasers

We present distributed feedback quantum cascade lasers at 965 cm/sup -1/ with a high average optical output power at temperatures of up to 60/spl deg/C. At a duty cycle of 3%, the averaged maximal output power of a 55-μm wide and 1.5-mm-long device at -30/spl deg/C was 13.6 mW; at 60/spl deg/C, the device emitted 2 mkV. Corresponding peak optical powers of 450 mW at -30/spl deg/C and of 70 mW at 60/spl deg/C have been observed. Due to the lateral current injection, we achieved single-mode behavior in a slightly distorted zero-order lateral mode across the whole range of investigated temperatures and output powers. At room temperature, the threshold current density was on the order of 6.7 kA/cm²; the characteristic temperature T₀ was, due to tuning of the Bragg resonance into the gain curve, rather high, namely 310 K.