High-Duty-Cycle Operation of GaAs/AlGaAs Quantum Cascade Laser above Liquid Nitrogen Temperature

We present a detailed study of λ ～ 9.75μm GaAs/AlGaAs quantum cascade lasers. For a coated 2-mm-long and 40-μm-wide laser, an optical power of 85μW is observed at 95% duty cycle at 80K. At a moderate driving pulse (1kHz and 1% duty cycle), the device presents a peak power more than 20mW even at 120K. At 80K, the fitted result of threshold current densities shows evidence of potential cw operation.