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 of120A/cm2 and a wall-plug efficiency of 0.92%at 10 K and 404 mW at 77 K 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/cm~2 and a wall-plug efficiency of 1.32%is achieved at 10 K. 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 the material structure and device processing, the peak optical output power of 758 mW with a threshold current density of 120 A / cm 2 and a wall-plug efficiency of 0.92% at 10 K and 404 mW at 77 K 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 / cm ~ 2 and a wall-plug efficiency of 1.32% is achieved at 10 K.