Photonics Research, Volume. 10, Issue 3, 703(2022)
Broadly tunable lens-coupled nonlinear quantum cascade lasers in the sub-THz to THz frequency range
Fig. 1. Scanning electron microscope images of (a) a partially buried heterostructure quantum cascade laser (QCL) device and (b) the improved buried heterostructure device in this work. (c) Temperature-dependent mid-IR (MIR) light-current-voltage curves of a 13.7 μm quantum cascade laser. A room temperature emission spectrum is shown in the inset.
Fig. 2. (a) THz nonlinear QCL device with abutted Si lens. (b), (c) Results of 3D COMSOL simulations of the Cherenkov THz power intensity when outcoupled from the device into (b) Si and (c) air. Upper figures of (b) and (c) display the simulated magnetic field (
Fig. 3. Performance of a 3 mm long, 16 μm wide nonlinear-QCL with multimode spectra when operated at 288 K. Emission spectra for (a) MIR and (b) THz at various currents. (c) Peak THz output powers versus products of the MIR pump powers for the device with and without the Si lens.
Fig. 4. Measured far-field beam patterns: (a) no-lens device and (b) lens-coupled device. A 2D far-field profile for the lens-coupled device is also shown in the inset.
Fig. 5. (a) THz light output-current-voltage characteristics of the 16 μm wide and 3 mm long QCL device at different heat-sink temperatures when measured in pulsed mode (pulse width of 250 ns and repetition rate of 100 kHz). (b) THz spectra at different temperatures.
Fig. 6. (a) Schematic of Si lens-coupled EC system setup used in the experiments. (b) Light output-current characteristics of the MIR and THz emissions from the THz EC system with a nonlinear QCL when operating at 420 GHz. The THz emission spectrum measured at a current density of
Fig. 7. Far-field THz emission profile of the EC lens-coupled QCL device described in Fig.
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Kazuue Fujita, Shohei Hayashi, Akio Ito, Tatsuo Dougakiuchi, Masahiro Hitaka, Atsushi Nakanishi. Broadly tunable lens-coupled nonlinear quantum cascade lasers in the sub-THz to THz frequency range[J]. Photonics Research, 2022, 10(3): 703
Category: Optoelectronics
Received: Sep. 20, 2021
Accepted: Jan. 10, 2022
Published Online: Feb. 22, 2022
The Author Email: Kazuue Fujita (kfujita@crl.hpk.co.jp)