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Broadband THz quantum cascade lasers frequency combs: high temperature operation and harmonic state
(2020)OSA Technical DigestWe report about high temperature comb operation of THz quantum cascade lasers. The extremely diagonal nature of the optical transition combined with low loss copper-based double-metal waveguides allow CW operation up to 105 K and CW power in excess of 5 mW measured at 80 K. Terahertz emission spanning up to 600 GHz together with a narrow beatnote indicate comb operation at 80 K and strong RF injection modifies clearly the laser spectrum ...Conference Paper -
Integrated Plasmonic Terahertz Field Detector
(2020)OSA Technical Digest ~ Frontiers in Optics 2020We present a compact and silicon compatible THz field detector platform. An optimum nonlinear interaction of the infrared and THz modes in a plasmonic waveguide-cavity enables a broadband and highly efficient detection.Conference Paper -
Post-processing GHz-level frequency tuning of THz Quantum Cascade Lasers
(2020)2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)Frequency red tuning down to GHz-level is shown in THz Quantum Cascade Lasers, by post-processing alteration of the device. Changing the height difference between the active region and surrounding material (and reapplying a material of known refractive index with appropriate thickness), the mode effective refractive index is increased, causing the device to lase at a lower frequency.Conference Paper -
Electro-optic interface for ultrasensitive intra-cavity electric field sensing
(2020)2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)We demonstrate a fibre-coupled, fully monolithic electro-optic coherent interface on the silicon-photonics platform that senses terahertz electric fields with sub-cycle resolution by means of nonlinear coupling with photons at telecom frequencies. A strong confinement of the terahertz field to a cavity mode enables a coupling strength to sense fields as low as 20 V/m. We discuss the opportunities such platforms provide for sensing of ...Conference Paper -
Perspectives on electrically pumped Ge/SiGe QW emitters at THz frequencies
(2020)2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)The realization of a Ge/SiGe THz emitter is of great interest since it can help to reach room-temperature operation due to the peculiar electron-phonon interaction in nonpolar crystals. Here we present Ge/SiGe quantum-well building blocks epitaxially grown on silicon wafers in order to understand limitations of this material platform in the perspective of realizing a Si-based laser.Conference Paper -
Terahertz intersubband electroluminescence from ZnO quantum cascade structures
(2020)2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)Terahertz intersubbband electrolulminescence from ZnO quantum cascade structures, based on four quantum well per period, is presented. The whole cascade structure was grown on the m-plane ZnO substrate. An electroluminescence peak with a linewidth of ~ 20 me V is observed at 8.5 THz, in consistent with the numerical simulation by a density matrix model.Conference Paper -
Continuous wave lasing in strained germanium microbridge
(2020)2020 IEEE Photonics Conference (IPC)Lasing in the Mid-Infrared region at 3.98 μm is achieved upon 2.15 μm continuous wave excitation in undoped germanium microbridge strained at 6.1 % at low temperature, revealing a closed offset between the G and L valleys. © 2020 IEEE.Conference Paper -
Numerical Optimization of Quantum Cascade Detector Heterostructures
(2020)2020 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)We demonstrate a Bayesian optimization framework for quantum cascade (QC) devices in the mid-infrared (midIR) and terahertz (THz) regime. The optimization algorithm is based on Gaussian process regression (GPR) and the devices are evaluated using a perturbed rate equation approach based on scattering rates calculated self-consistently by Fermi’s golden rule or alternatively extracted from an Ensemble Monte Carlo (EMC) simulation tool. ...Conference Paper -
Monte Carlo Modeling of Terahertz Quantum Cascade Detectors
(2020)2020 XXXIIIrd General Assembly and Scientific Symposium of the International Union of Radio ScienceWe demonstrate an Ensemble Monte Carlo (EMC) modeling approach for robust and rigorous simulations of photovoltaic quantum cascade detectors (QCDs) in the mid-infrared (mid-IR) and terahertz (THz) range. The existing EMC simulation tool for quantum cascade lasers (QCLs) was extended to simulate the photovoltaic transport effects in QCDs at thermal equilibrium under zero bias. Here, we present the results of the EMC study of a THz detector ...Conference Paper -
Terahertz Quantum Cascade Laser Frequency Comb Operation of a Coupled Waveguide Array
(2020)2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)We present a terahertz quantum cascade laser array of laterally coupled waveguides with varying length. At a relatively low bias, a regular mode spacing and a single beatnote are observed, which are signatures of frequency comb operation. The comb spectrum spans 650 GHz and consists of groups of modes separated by a multiple of the mode spacing, indicating that the waveguides combine to form a global comb.Conference Paper