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Kampfrath, Tobias; Perfetti, Luca; von Volkmann, Konrad; Aguirre, Carla M.; Desjardins, Patrick; Martel, Richard; Frischkorn, Christian; Wolf, Martin |
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Optical response of single-wall carbon nanotube sheets in the far-infrared spectral range from 1 THz to 40 THz |
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2007 |
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Physica Status Solidi (B) |
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Phys. Stat. Sol. (B) |
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244 |
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11 |
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3950-3954 |
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single wall, carbon nanotube, SWNT, SWCNT, CNT, detector, sensor, TDS |
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The optical properties of single-wall carbon nanotube sheets in the far-infrared have been investigated with THz time-domain spectroscopy. Over a wide frequency range from 1 THz to 40 THz, the complex dielectric function of the nanotube sample has been derived. Our data can be excellently reproduced by a Drude-Lorentz model function. The extracted fit parameters such as Lorentz resonance frequency and plasma frequency are consistent with values obtained by scanning tunneling techniques. We discuss the origin of both the Lorentz and Drude contribution in terms of direct and indirect optical transitions. |
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0370-1972 |
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569 |
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Zhizhon, Yan; Majedi, Hamed A. |
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Optoelectronic mixing in the NbN superconducting nanowire single photon detectors |
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2009 |
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Proc. SPIE |
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Proc. SPIE |
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3786 |
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9 |
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Optoelectronic devices, microwave superconductivity, nonlinearity, single photon detector, superconductivity, nanowire, optical mixing, microwave mixers, amplitude modulation, intensity modulation. |
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In this paper, we present our experimental results on the electrically pumped optoelectronic mixing effect exhibited in a niobium nitride (NbN) superconducting nanowire. The experimental setup in order to test the mixer has been reported in detail. This superconductive nanowire optoelectronic mixer demonstrates photodetection and mixing in an integrated manner. We have explored both effects under a great variety of external conditions, such as temperature and bias current, in order to seek potential ways toward quantum optoelectronic detection and mixing by such nanowire device. |
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RPLAB @ gujma @ |
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651 |
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Shurakov, Alexander; Maslennikov, Sergey; Tong, Cheuk-yu E.; Gol’tsman, Gregory |
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Performance of an HEB direct detector utilizing a microwave reflection readout scheme |
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2015 |
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Proc. 26th Int. Symp. Space Terahertz Technol. |
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Proc. 26th Int. Symp. Space Terahertz Technol. |
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36 |
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HEB detector |
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We report the results of our study on the performance of a hot electron bolometric (HEB) direct detector, operated by a microwave pump. The HEB devices used in this work were made from NbN thin film deposited on high resistivity silicon with an in-situ fabrication process. The experimental setup employed is similar to the one described in [1]. The detector chips were glued to a silicon lens clamped to a copper holder mounted on the cold plate of a liquid helium cryostat. Thermal link between the lens and the holder was maintained by a thin indium shim. The HEBs were operated at a bath temperature of about 4.4 K. Conventional phonon pump, commonly realized by raising the bath temperature of the detector, was substituted by a microwave one. In this case, a CW microwave signal is injected to the device through a directional coupler connected directly to the detector holder. The power incident on the HEB device was typically 1-2 μW, and the pump frequency was in the range of 0.5-1.5 GHz. The signal sources were 2 black bodies held at temperatures of 295 K and 77 K. A chopper wheel placed in front of the cryostat window switched the input to the detector between the 2 sources. A modulation frequency of several kilohertz was chosen in order to reduce the effects of the HEB’s flicker noise. A cold mesh filter was used to define the input bandwidth of the detector. The reflected microwave signal from the HEB device was fed into a low noise amplifier, the output of which is connected to a room temperature Schottky microwave power detector. This Schottky detector, in conjunction with a lock-in amplifier, demodulated the input signal modulation from the copper wheel. As the input load was switched, the impedance of the HEB device at the microwave pump frequency also changed in response to the incident signal power variation. Therefore the reflected microwave power follows the incident signal modulation. The derived responsivity from this detection system nicely correlates with the HEB impedance. In order to provide a quantitative description of the impedance variation of the HEB device and the impact of a microwave pump, we have numerically solved the heat balance equations written for the NbN bridge and its surrounding thermal heat sink [2]. Our model also accounts for the impact of the operating frequency of the detector because of non-uniform absorption of low-frequency photons across the NbN bridge [3]. In our measurements we varied the signal source wavelength from 2 mm down to near infrared range, and hence we indirectly performed the impedance measurements at frequencies below, around and far beyond the superconducting gap. Preliminary results show good agreement between the experiment and theoretical prediction. Further measurements are still in progress. [1] A. Shurakov et al., “A Microwave Reflection Readout Scheme for Hot Electron Bolometric Direct Detector”, to appear in IEEE Trans. THz Sci. Tech., 2015. [2] S. Maslennikov, “RF heating efficiency of the terahertz superconducting hot-electron bolometer”, http://arxiv.org/pdf/1404.5276v5.pdf, 2014. [3] W. Miao et al., “Non-uniform absorption of terahertz radiation on superconducting hot electron bolometer microbridges”, Appl. Phys. Let., 104, 052605, 2014. |
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Zhang, Zijing; Zhang, Jianlong; Wu, Long; Zhang, Yong; Zhao, Yuan; Su, Jianzhong |
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Photon-counting chirped amplitude modulation lidar using a smart premixing method |
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2013 |
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Opt. Lett. |
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Opt. Lett. |
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38 |
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21 |
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4389-4392 |
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photon-counting detector, lidar, Geiger mode APD, Geiger mode lidar |
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We proposed a new premixing method for photon-counting chirped amplitude modulation lidar (PCCAML). Earlier studies used the counting results of the returned signal detected by a Geiger mode avalanche photodiode detector (Gm-APD) to mix with the reference signal, called the postmixing method. We use an alternative method known as the premixing method, in which the reference signal is used to directly modulate the sampling gate width of the Gm-APD, and the mixing of the returned signal and the reference signal is completed before the Gm-APD. This premixing method is more flexible and may perform better than the postmixing method in terms of signal-to-noise ratio by cutting down a separated mixer commonly used in the postmixing lidar system. Furthermore, this premixing method lowers the demand for the sampling frequency of the Gm-APD. It allows the use of a much wider modulation bandwidth to improve the range accuracy and resolution. To the best of our knowledge, this is the first report to use the premixing method in the PCCAML system, which will benefit future lidar applications. |
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1006 |
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Dauler, Eric; Kerman, Andrew; Robinson, Bryan; Yang, Joel; Voronov, Boris; Goltsman, Gregory; Hamilton, Scott; Berggren, Karl |
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Photon-number-resolution with sub-30-ps timing using multi-element superconducting nanowire single photon detectors |
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2009 |
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J. Modern Opt. |
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J. Modern Opt. |
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56 |
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2 |
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364-373 |
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PNR SSPD; SNSPD; photon-number-resolution; superconducting nanowire single photon detector; timing jitter; system detection efficiency |
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A photon-number-resolving detector based on a four-element superconducting nanowire single photon detector is demonstrated to have sub-30-ps resolution in measuring the arrival time of individual photons. This detector can be used to characterize the photon statistics of non-pulsed light sources and to mitigate dead-time effects in high-speed photon counting applications. Furthermore, a 25% system detection efficiency at 1550 nm was demonstrated, making the detector useful for both low-flux source characterization and high-speed photon-counting and quantum communication applications. The design, fabrication and testing of this detector are described, and a comparison between the measured and theoretical performance is presented. |
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RPLAB @ gujma @ |
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700 |
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