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arXiv · 2306.10360

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

Urban Senica·Sebastian Gloor·Paolo Micheletti·David Stark·Mattias Beck·Jérôme Faist·Giacomo Scalari
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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{\deg}x 18.5{\deg}), while broadband fundamental and harmonic comb states spanning up to 800 GHz are observed.

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Urban Senica, Sebastian Gloor, Paolo Micheletti, David Stark, Mattias Beck, Jérôme Faist, Giacomo Scalari. 2023-06-17. Broadband surface-emitting THz laser frequency combs with inverse-designed integrated reflectors. https://doi.org/10.1063/5.0163337

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