Continuous wave operation of a superlattice quantum cascade laser emitting at 2 THz.

We report the operation of a 2 THz quantum cascade laser based on a GaAs/Al(0.1)Ga(0.9)As heterostructure. The laser transition is between an isolated subband and the upper state of a 14 meV wide miniband. Lasing action takes place on a high order vertical mode of a 200 microm thick double-metallic waveguide. In pulsed mode operation, with a 3.16mm long device, we report a threshold current density of 115 A/cm(2) at T = 4K, with a maximum measured peak power of 50 mW. The device shows lasing action in continuous wave up to 47K, with a maximum power in excess of 15 mW at T = 4K.