Broadband surface-emitting THz laser frequency combs with inverse-designed integrated reflectors
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Date
2023-09-01
Publication Type
Journal Article
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yes
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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.
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published
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Journal / series
Volume
8 (9)
Pages / Article No.
96101
Publisher
American Institute of Physics
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Subject
Waveguides; Antennas; Optimization algorithms; Frequency combs; Integrated optics devices; Optical resonators; Terahertz laser; Laser resonators; Laser physics; Laser fabrication
Organisational unit
03759 - Faist, Jérôme / Faist, Jérôme
02205 - FIRST-Lab / FIRST Center for Micro- and Nanoscience