paper

Broadband surface-emitting THz laser frequency combs with inverse-designed integrated reflectors

arXiv:2306.10360 · doi:10.1063/5.0163337

Abstract

THz quantum cascade lasers (QCLs) based on double metal waveguides feature broadband and high-temperature devices for use in spectroscopy and sensing. However, their extreme field confinement produces poor output coupling efficiencies and divergent far-fields. Here, we present a planarized THz QCL with an inverse-designed end facet reflector coupled to a surface-emitting patch array antenna. All the components have been optimized for octave-spanning spectral bandwidths between 2-4 THz and monolithically integrated on the same photonic chip. We demonstrate this experimentally on broadband THz QCL frequency combs, with measured devices showing a seven-fold improvement in slope efficiency compared to devices with a cleaved facet. They feature peak powers of up to 13.5 mW with surface emission into a narrow beam with a divergence of (17.0°x 18.5°), while broadband fundamental and harmonic comb states spanning up to 800 GHz are observed.

6 pages, 5 figures

References in corpus (5)

Broadband surface-emitting THz laser frequency combs with inverse-designed integrated reflectors · wovepaper