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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 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 -
Broadband active and passive photonics with planarized THz quantum cascade lasers
(2022)Other Conference Item -
Planarized tapered waveguides for high-temperature THz quantum cascade laser frequency combs
(2022)2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)We present a novel planarized double metal waveguide platform for high-performance THz quantum cascade laser frequency combs. The waveguides are embedded in a low-loss polymer (BCB) and have an extended top metallization, resulting in lower waveguide losses and improved RF and thermal properties. A further performance improvement is observed for waveguides with a tapered profile due to nonlinearity-enhancing effects. These free-running ...Other Conference Item -
High speed response of a Hot Electron Bolometer to a picosecond optical THz source and to a THz QCL comb up to 31GHz
(2022)2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)We have investigated the frequency response of a phonon-cooled Hot Electron Bolometer (HEB) made from an ultrathin superconducting niobium nitride film. We have used short optical pulses and a broadband spectrum analyzer to record the impulse response of the HEB. To interpret the experimental results, we have used numerical calculations based on the two temperature (2T) theoretical model.Other Conference Item -
FM to AM Transition of RF Driven THz QCL fundamental and Harmonic Comb States
(2022)2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)We measure temporal intensity profile by means of Shifted Wave Interference Fourier Transform Spectroscopy of strong RF injected heterogeneous THz QCLs showing a strong AM emission with pulses as short as 6 ps. Additionally, we measure with SWIFTS fundamental as well as harmonic comb states under RF injection which exhibit clear FM emission and its transition to AM as a function of the RF power.Other Conference Item