An antipodal Vivaldi antenna for improved far-field properties and polarization manipulation of broadband terahertz quantum cascade lasers

Senica, Urban; Mavrona, Elena; Olariu, Tudor; Forrer, Andres; Shahmohammadi, Mehran; Beck, Mattias; Faist, Jérôme; Scalari, Giacomo

doi:10.1063/5.0004038

Cited by 8 publications

(2 citation statements)

References 32 publications

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“…Another important advantage of our planarized platform is the possibility to co-integrate active and passive elements. While we have already demonstrated planar reflective and outcoupling passive antenna structures 21 , 51 , here we designed passive waveguides for on-chip signal routing between various elements. Integration of passive waveguides is critical in the development of an integrated photonic platform.…”

Section: Resultsmentioning

confidence: 99%

Planarized THz quantum cascade lasers for broadband coherent photonics

et al. 2022

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Recently, there has been a growing interest in integrated THz photonics for various applications in communications, spectroscopy and sensing. We present a new integrated photonic platform based on active and passive elements integrated in a double-metal, high-confinement waveguide layout planarized with a low-loss polymer. An extended top metallization keeps waveguide losses low while improving dispersion, thermal and RF properties, as it enables to decouple the design of THz and microwave cavities. Free-running on-chip quantum cascade laser combs spanning 800 GHz, harmonic states with over 1.1 THz bandwidth and RF-injected broadband incoherent states spanning over nearly 1.6 THz are observed using a homogeneous quantum-cascade active core. With a strong external RF drive, actively mode-locked pulses as short as 4.4 ps can be produced, as measured by SWIFTS. We demonstrate as well passive waveguides with low insertion loss, enabling the tuning of the laser cavity boundary conditions and the co-integration of active and passive elements on the same THz photonic chip.

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Section: Resultsmentioning

confidence: 99%

Planarized THz quantum cascade lasers for broadband coherent photonics

et al. 2022

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“…Since the waveguide thickness is subwavelength, this also results in poor farfield properties, which are highly divergent and frequency-dependent. While these challenges have been addressed in the last decade, the existing solutions are either frequency selective (DFBs, photonic crystals [5]) or non-monolithic, requiring additional post-processing and mounting steps (lenses [6], antennas [7]).…”

Section: Introductionmentioning

confidence: 99%

Broadband THz quantum cascade laser frequency combs with surface emission and inverse-designed facet reflectors

Senica,

Gloor,

Micheletti

et al. 2023

EPJ Web Conf.

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We present a planarized waveguide cavity with an integrated broadband output coupler that improves both the output power and far-field properties of THz quantum cascade laser frequency combs. The laser mirror reflectivity can be tuned by the shape of the end facet, which is obtained with an efficient inverse design algorithm, where the structure is iteratively updated to match the desired figure of merit. Surface emission is achieved with a broadband patch-array antenna, and all the components have been optimized for octave-spanning emission spectra (2-4 THz). Experimentally, we demonstrate a broadband surface-emitting THz quantum cascade laser frequency comb with optical bandwidths of up to 800 GHz, surface emission into a narrow beam with divergence below (20° x 20°) and a peak power of 13 mW.

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

Senica,

Gloor,

Micheletti

et al. 2023

APL Photonics

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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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An antipodal Vivaldi antenna for improved far-field properties and polarization manipulation of broadband terahertz quantum cascade lasers

Cited by 8 publications

References 32 publications

Planarized THz quantum cascade lasers for broadband coherent photonics

Planarized THz quantum cascade lasers for broadband coherent photonics

Broadband THz quantum cascade laser frequency combs with surface emission and inverse-designed facet reflectors

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

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