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Author Sekine, Norihiko; Hosako, Iwao
Title (up) 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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Call Number Serial 630
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Author Walther, Christoph; Scalari, Giacomo; Faist, Jerome; Beere, Harvey; Ritchie, David
Title (up) 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 Dorenbos, S. N.; Reiger, E. M.; Perinetti, U.; Zwiller, V.; Zijlstra, T.; Klapwijk, T. M.
Title (up) Low noise superconducting single photon detectors on silicon Type Journal Article
Year 2008 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume 93 Issue 13 Pages 131101
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ISSN 0003-6951 ISBN Medium
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Notes Approved no
Call Number RPLAB @ s @ Serial 436
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Author Gaggero, A.; Nejad, S. Jahanmiri; Marsili, F.; Mattioli, F.; Leoni, R.; Bitauld, D.; Sahin, D.; Hamhuis, G. J.; Nötzel, R.; Sanjines, R.; Fiore, A.
Title (up) Nanowire superconducting single-photon detectors on GaAs for integrated quantum photonic applications Type Journal Article
Year 2010 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume 97 Issue 15 Pages 3
Keywords SSPD
Abstract We demonstrate efficient nanowire superconducting single photon detectors (SSPDs) based on NbN thin films grown on GaAs. NbN films ranging from 3 to 5 nm in thickness have been deposited by dc magnetron sputtering on GaAs substrates at 350 °C. These films show superconducting properties comparable to similar films grown on sapphire and MgO. In order to demonstrate the potential for monolithic integration, SSPDs were fabricated and measured on GaAs/AlAs Bragg mirrors, showing a clear cavity enhancement, with a peak quantum efficiency of 18.3% at λ = 1300 nm and T = 4.2 K.
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Call Number RPLAB @ gujma @ Serial 681
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Author Siddiqi, I.; Prober, D. E.
Title (up) Nb–Au bilayer hot-electron bolometers for low-noise THz heterodyne detection Type Journal Article
Year 2004 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume 84 Issue 8 Pages 1404
Keywords HEB, mixers, dynamic range, saturation, LO power, local oscillator power, Nb
Abstract The sensitivity of present Nb diffusion-cooled hot-electron bolometer (HEB) mixers is not quantum limited, and can be improved by reducing the superconducting transition temperature TC. Lowering TC reduces thermal fluctuations, resulting in a decrease of the mixer noise temperature TM. However, lower TC mixers have reduced dynamic range and saturate more easily due to background noise. We present 30 GHz microwave measurements on a bilayer HEB system, Nb–Au, in which TC can be tuned with Au layer thickness to obtain the maximum sensitivity for a given noise background. These measurements are intended as a guide for the optimization of THz mixers. Using a Nb–Au mixer with TC = 1.6 K, we obtain TM = 50 K with 2 nW of local oscillator (LO) power. Good mixer performance is observed over a wide range of LO power and bias voltage and such a device should not exhibit saturation in a THz receiver.
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ISSN 0003-6951 ISBN Medium
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Notes Approved no
Call Number Serial 571
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