Broadband THz lasing from a photon-phonon quantum cascade structure.

Laser emission over a broad range of frequencies from 2.8 to 4.1 THz is reported for a two-quantum well, photon-phonon cascade structure. Maximum operating temperatures of 125 K are reported, with optical peak powers in eccess of 30 mW from a double-metal ridge waveguide. The broadband nature of the gain curve is identified as due to coherent coupling of the injector and upper lasing states. Internal quantum efficiencies reaching 43 % are evaluated at 10 K.The laser operates in both polarities, showing laser action in reverse bias up to a temperature of 90 K. Simulations based on a full treatment of the structure with density matrix formalism are also presented and discussed.