Invited - Terahertz quantum cascade lasers

Abstract

Quantum cascade lasers operating at far-infrared (terahertz) frequencies have now been demonstrated. We review the fabrication, operation, and performance of these lasers, and indicate recent results in which devices have been developed to operate continuous wave, at temperatures greater than 77 K, emit at frequencies down to 3.5 THz, and produce tens of milli-Watts of power. These results are an encouraging step towards a widely applicable solid-state terahertz source, and the development of terahertz photonics.