High-Power and High-Efficiency Operation of Terahertz Quantum Cascade Lasers at 3.3 THz**Supported by the National Basic Research Program of China under Grant Nos 2014CB339803 and 2013CB632801, and the National Natural Science Foundation of China under Grant No 61376051.

Abstract

A high-power and high-efficiency GaAs/AlGaAs-based terahertz (THz) quantum cascade laser structure emitting at 3.3 THz is presented. The structure is based on a hybrid bound-to-continuum transition and resonant-phonon extraction active region combined with a semi-insulating surface-plasmon waveguide. By optimizing material structure and device processing, the peak optical output power of 758 mW with a threshold current density of 120 A/cm2 and a wall-plug efficiency of 0.92% at 10K and 404mW at 77K are obtained in pulsed operation. The maximum operating temperature is as high as 115 K. In the cw mode, a record optical output power of 160 mW with a threshold current density of 178 A/cm2 and a wall-plug efficiency of 1.32% is achieved at 10 K.