Transient Analysis of THz-QCL Pulses Using NbN and YBCO Superconducting Detectors
| Autor: | Alexander Valavanis, Andrew Grier, Stefan Wuensch, Edmund H. Linfield, S. Chowdhury, Suraj P. Khanna, P. Thoma, J. D. Cooper, Michael Siegel, Alexander Scheuring, Paul Dean, Konstantin Ilin, M. Salih, A. Stockhausen, Alexander Giles Davies |
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| Rok vydání: | 2013 |
| Předmět: |
010302 applied physics
Radiation Materials science Physics::Instrumentation and Detectors business.industry Terahertz radiation Bolometer Detector Physics::Optics Biasing 02 engineering and technology Nanosecond 021001 nanoscience & nanotechnology 01 natural sciences law.invention law Modulation 0103 physical sciences Optoelectronics Electrical and Electronic Engineering 0210 nano-technology Quantum cascade laser business Ultrashort pulse |
| Zdroj: | IEEE Transactions on Terahertz Science and Technology |
| ISSN: | 2156-3446 2156-342X |
| Popis: | We report the time-domain analysis of fast pulses emitted by a quantum cascade laser (QCL) operating at ~3.1 THz using superconducting THz detectors made from either NbN or YBa2Cu3O7- (YBCO) thin films. The ultra-fast response from these detectors allows resolution of emission features occurring on a nanosecond time-scale, which is not possible with commercially available Ge or InSb bolometers owing to their much larger time constants. We demonstrate that the time-dependent emission can be strongly affected by relatively small variations in the driving pulse. The QCL output power–current relationship was determined, based on correlation of the time-dependent emission of radiation with current flow in the QCL, under different QCL bias conditions. We show that this relationship differs from that obtained using bolometric detectors that respond only to the integrated pulse energy. The linearity of the detectors, and their agreement with measurements using a Ge bolometer, was also established by studying the QCL emission as a function of bias voltage and excitation pulse length. This measurement scheme could be readily applied to the study of ultra-fast modulation and mode-locking of THz-QCLs. |
| Databáze: | OpenAIRE |
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