Mesa-type quantum cascade lasers fabricated by using inductively coupled plasma reactive ion etching

Mesa-type and ridge-type InGaAs/InAlAs double-channel quantum cascade lasers (QCLs) emitting 8.15 μm wavelength were fabricated by using metal–organic chemical vapour deposition and inductively coupled plasma reactive ion etching techniques. The output power, threshold current, characteristic temperature (T 0), and slope efficiency were compared. The smooth and vertical sidewall profile enabled mesa-type QCL to exhibit the higher output power, the lower threshold current, and the higher slope efficiency than the ridge-type QCL.