Low-loss GaInAs-based waveguides for high-performance 5.5 μm InP-based quantum cascade lasers

Plasmon-enhanced GaInAs-waveguides have been successfully employed for the fabrication of 5.5 μm GaInAs/AlInAs strain-compensated quantum cascade lasers using solid-source molecular beam epitaxy (MBE). The low-loss waveguide design combined with the high injection efficiency of the band-structure results in a very high operating temperature of the devices. Laser action for a 2.7 mm long and 22 μm wide device with uncoated facets was achieved in pulsed mode up to a temperature of 450 K. The measured value of the waveguide loss at room-temperature is 7 cm^-1. The observed temperature dependence of the waveguide loss is explained by means of the thermal behaviour of the electron mobility.