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High-performance THz QCL frequency combs
(2020)Proceedings of SPIE ~ Quantum Sensing and Nano Electronics and Photonics XVIIA broadband, Cu-Cu THz quantum cascade laser is presented. The device shows an 50% improved dynamical range and doubled peak power in pulsed compared to Au-Au devices. The pulsed maximum lasing temperature was increased from 105 K to 133 K. In CW similar bandwidths for Cu-Cu and Au-Au devices are observed with an increased temperature performance. At 77 K the emitted power of the device is reduced by 57% compared to 30 K. At this temperature ...Other Conference Item -
Linewidth Enhancement Factor of Mid-IR Quantum Cascade Lasers
(2021)2021 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)Schawlow and Townes theorized that the ratio between the spontaneous emission and stimulated emission in a semiconductor laser defines its linewidth lower limit [1] . However, experiments showed that this intrinsic linewidth is larger, which was later demonstrated to be due to the coupling between the optical gain and the phase noise [2] . The linewidth enhancement factor (LEF) was introduced to quantify this process and as a correction ...Other Conference Item -
Planarized waveguides for high-performance THz quantum cascade laser frequency
(2022)Proceedings of SPIE ~ Quantum Sensing and Nano Electronics and Photonics XVIIIWe present a planarized double metal waveguide THz quantum cascade laser, where the top contact metallization extends beyond the active region, above the surrounding low-loss BCB polymer. Placing wire bonds over the BCB-covered area enables the fabrication of extremely narrow waveguide dimensions with reduced power dissipation. Compared to a standard double metal waveguide, improvements in waveguide losses, dispersion, RF and thermal ...Other Conference Item -
Field-enhancing tapered planarized waveguides for THz quantum cascade laser frequency combs
(2022)EPJ Web of Conferences ~ EOS Annual Meeting (EOSAM 2022)We present a new planarized waveguide geometry for THz quantum cascade laser frequency combs with improved waveguide losses, RF and thermal dissipation properties. Ridge devices display broadband free-running comb states, and the THz emission can be further broadened by RF injection. Tapered waveguide devices feature a strong field-enhancement effect, which results in an improved comb performance. This includes free-running comb states ...Other Conference Item -
THz Quantum Cascade Laser Frequency Combs based on Planarized Waveguides
(2022)OSA Technical Digest ~ Conference on Lasers and Electro-OpticsWe present a planarized double metal waveguide platform for THz quantum cascade laser frequency combs with a wide top metallization, extending above the surrounding low-loss BCB polymer. Compared to a standard double metal waveguide, improvements in waveguide losses, RF and thermal properties are observed. Tapered waveguide devices display a field-enhancing effect, improving comb performance due to the enhanced four wave mixing process. ...Other Conference Item -
Terahertz Frequency Combs from Dispersion Compensated Quantum Cascade Ring Lasers
(2022)Proceedings of SPIE ~ Laser Resonators, Microresonators, and Beam Control XXIVWe report frequency combs formation in THz QCL ring cavities. The double metal waveguide laser is encapsulated in benzocyclobutene (BCB) on which the top contact is deposited. This allows to explore alternative designs such as ultrathin ring cavities and coupled double ring waveguides avoiding issues with the electrical connection of the. Ring laser operating in dense comb regime with spectral bandwidth of ~500 GHz is here reported. In ...Other Conference Item -
THz QCL combs under strong RF injection: temporal dynamics and harmonic states
(2022)Proceedings of SPIE ~ Novel In-Plane Semiconductor Lasers XXIIn this work present high performance QCL-based THz combs operating on fundamental and harmonic comb states operating up to 110 K in the spectral region from 2 to 4 THz . We employ double-metal, Copper- based laser resonators planarized with a polymer allowing high performance with CW operation up to 118 K . Such waveguide layout allows as well optimized RF coupling facilitating injection of high RF power. We analyze the laser emission ...Other Conference Item -
Spectral phase relation in broadband THz quantum cascade laser frequency combs under strong RF modulation
(2022)Proceedings of SPIE ~ Quantum Sensing and Nano Electronics and Photonics XVIIITHz QCLs are promising sources towards achieving octave-spanning comb operation and self-referencing in a monolithic device. We investigate the spectral mode phase relations by means of SWIFT of free running and strongly RF modulated devices. The inspected QCLs are based on an octave-spanning, heterogeneous and a 1.8 THz spanning, homogeneous active region design. The extracted neighboring mode phase differences from SWIFT of free running ...Other Conference Item -
Planarized tapered waveguides for THz quantum cascade laser frequency combs
(2022)Proceedings of SPIE ~ Terahertz Photonics IITerahertz (THz) quantum cascade lasers (QCLs) based on double metal waveguides are compact sources of broadband THz radiation, which can also operate as frequency combs. We present a planarized double metal waveguide THz QCL platform, where the active region is embedded in a low-loss BCB polymer and covered by an extended top metallization. The latter enables placing bonding wires on the sides above the BCB-covered area, hindering the ...Other Conference Item -
Shifted Wave Interference Fourier Transform Spectroscopy of Harmonic and Fundamental RF Injection-Locked THz Quantum Cascade Laser Frequency Combs
(2021)2021 27th International Semiconductor Laser Conference (ISLC)Shifted Wave Interference Fourier Transform Spectroscopy allows us to reveal the temporal intensity profiles of RF injection-locked fundamental and harmonic comb states of a broadband, multi-stack THz Quantum Cascade Laser. Depending on the injection power and frequency AM and FM modulated emission can be observed.Other Conference Item