1. Broadband surface-emitting THz laser frequency combs with inverse-designed integrated reflectors.
- Author
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Senica, Urban, Gloor, Sebastian, Micheletti, Paolo, Stark, David, Beck, Mattias, Faist, Jérôme, and Scalari, Giacomo
- Subjects
SURFACE emitting lasers ,QUANTUM cascade lasers ,ANTENNA arrays - Abstract
THz quantum cascade lasers (QCLs) based on double metal waveguides feature broadband and high-temperature devices for their 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 and 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 a peak power of up to 13.5 mW with surface emission into a narrow beam with a divergence of (17.0° × 18.5°), while broadband fundamental and harmonic comb states spanning up to 800 GHz are observed. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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