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Author Морозов, Дмитрий Владимирович
Title Приемные устройства терагерцового диапазона на эффекте разогрева двумерного электронного газа в гетероструктурах AlGaAs/GaAs Type Manuscript
Year 2007 Publication М. МПГУ Abbreviated Journal
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Corporate Author Thesis Ph.D. thesis
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Call Number RPLAB @ s @ Serial 626
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Author Huebers, Heinz-Wilhelm; Pavlov, S.; Semenov, A.; Köhler, R.; Mahler, L.; Tredicucci, A.; Beere, H.; Ritchie, D.; Linfield, E.
Title Terahertz quantum cascade laser as local oscillator in a heterodyne receiver Type Journal Article
Year 2005 Publication Optics Express Abbreviated Journal
Volume 13 Issue 15 Pages 5890-5896
Keywords QCL heterodyne, 6 mW at 2.5 THz, HEB mixer, terahertz
Abstract Terahertz quantum cascade lasers have been investigated with respect to their performance as a local oscillator in a heterodyne receiver. The beam profile has been measured and transformed in to a close to Gaussian profile resulting in a good matching between the field patterns of the quantum cascade laser and the antenna of a superconducting hot electron bolometric mixer. Noise temperature measurements with the hot electron bolometer and a 2.5 THz quantum cascade laser yielded the same result as with a gas laser as local oscillator.
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Call Number Serial 627
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Author Rabanus, D.; Graf, U. U.; Philipp, M.; Ricken, O.; Stutzki, J.; Vowinkel, B.; Wiedner, M. C.; Walther, C.; Fischer, M.; Faist, J.
Title Phase locking of a 1.5 terahertz quantum cascade laser and use as a local oscillator in a heterodyne HEB receiver Type Journal Article
Year 2009 Publication Optics Express Abbreviated Journal
Volume 17 Issue 3 Pages 1159-1168
Keywords QCL heterodyne, 300 uW at 1.5 THz, HEB mixer
Abstract We demonstrate for the first time the closure of an electronic phase lock loop for a continuous–wave quantum cascade laser (QCL) at 1.5 THz. The QCL is operated in a closed cycle cryo cooler. We achieved a frequency stability of better than 100 Hz, limited by the resolution bandwidth of the spectrum analyser. The PLL electronics make use of the intermediate frequency (IF) obtained from a hot electron bolometer (HEB) which is downconverted to a PLL IF of 125 MHz. The coarse selection of the longitudinal mode and the fine tuning is achieved via the bias voltage of the QCL. Within a QCL cavity mode, the free-running QCL shows frequency fluctuations of about 5 MHz, which the PLL circuit is able to control via the Stark–shift of the QCL gain material. Temperature dependent tuning is shown to be nonlinear, and of the order of -16 MHz/K. Additionally we have used the QCL as local oscillator (LO) to pump an HEB and perform, again for the first time at 1.5 THz, a heterodyne experiment, and obtain a receiver noise temperature of 1741 K.
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Call Number Serial 628
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Author Walther, Christoph; Scalari, Giacomo; Faist, Jerome; Beere, Harvey; Ritchie, David
Title Low frequency terahertz quantum cascade laser operating from 1.6 to 1.8 THz Type Journal Article
Year 2006 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume 89 Issue Pages 231121(1-3)
Keywords QCL, 360 uW at 1.6 THz
Abstract The authors report a GaAs/Al0.1Ga0.9As quantum cascade laser based on a bound-to-continuum transition optimized for low frequency operation. High tunability of the gain curve is achieved by the Stark effect and laser emission is measured between 1.6 and 1.8 THz. Pulsed mode operation up to 95 K and continuous wave operation up to 80 K are reported. The dynamical range in current is as high as 43%.
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Call Number Serial 629
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Author Sekine, Norihiko; Hosako, Iwao
Title Intensity modulation of terahertz quantum cascade lasers under external light injection Type Journal Article
Year 2009 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume 95 Issue Pages 201106(1-3)
Keywords QCL modulation, THz, terahertz
Abstract We investigated the light-current characteristics of terahertz (THz) quantum cascade lasers under external light injection, which excites interband transitions in the active materials. It was found that the amount of reduction in the THz power was constant for all injection currents above threshold, and the dependence of the reduction amount on the wavelength of the external light was observed to show a resonancelike feature. The dominant intensity modulation mechanism was found to be the loss change caused by interband transitions in the active region. Further, the effective coupling efficiency plays an important role in the intensity modulation.
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Notes Approved no
Call Number Serial 630
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