Waveguide integration of a >4.7-THz quantum-cascade laser

Abstract

Waveguide integration of terahertz quantum cascade lasers (THz QCLs) is demonstrated at frequencies above 4.7 THz. A precision micromachining technique, followed by diamond-turning and electroless-plating has been used to manufacture hollow rectangular waveguides with integrated diagonal feedhorns. It is shown that surface roughness at the (Formula presented.) level is achieved, enabling outcoupling of radiation in the 4.75–5.05 THz band, with a divergence angle of (Formula presented.) along the plane of the QCLs substrate.