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Marsili, F., Bitauld, D., Fiore, A., Gaggero, A., Mattioli, F., Leoni, R., et al. (2010). Photon-number-resolution at telecom wavelength with superconducting nanowires. IntechOpen [DOI:10.5772/6920]. Retrieved June 10, 2024, from http://dx.doi.org/10.5772/6920
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Marsili, F., Bitauld, D., Fiore, A., Gaggero, A., Leoni, R., Mattioli, F., et al. (2009). Superconducting parallel nanowire detector with photon number resolving functionality. J. Modern Opt., 56(2-3), 334–344.
Abstract: We present a new photon number resolving detector (PNR), the Parallel Nanowire Detector (PND), which uses spatial multiplexing on a subwavelength scale to provide a single electrical output proportional to the photon number. The basic structure of the PND is the parallel connection of several NbN superconducting nanowires (100 nm-wide, few nm-thick), folded in a meander pattern. Electrical and optical equivalents of the device were developed in order to gain insight on its working principle. PNDs were fabricated on 3-4 nm thick NbN films grown on sapphire (substrate temperature TS=900C) or MgO (TS=400C) substrates by reactive magnetron sputtering in an Ar/N2 gas mixture. The device performance was characterized in terms of speed and sensitivity. The photoresponse shows a full width at half maximum (FWHM) as low as 660ps. PNDs showed counting performance at 80 MHz repetition rate. Building the histograms of the photoresponse peak, no multiplication noise buildup is observable and a one photon quantum efficiency can be estimated to be QE=3% (at 700 nm wavelength and 4.2 K temperature). The PND significantly outperforms existing PNR detectors in terms of simplicity, sensitivity, speed, and multiplication noise.
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Maingault, L., Tarkhov, M., Florya, I., Semenov, A., Espiau de Lamaëstre, R., Cavalier, P., et al. (2010). Spectral dependency of superconducting single photon detectors. J. Appl. Phys., 107(11), 116103 (1 to 3).
Abstract: We investigate the effect of varying both incoming optical wavelength and width of NbN nanowires on the superconducting single photon detectors (SSPD) detection efficiency. The SSPD are current biased close to critical value and temperature fixed at 4.2 K, far from transition. The experimental results are found to verify with a good accuracy predictions based on the “hot spot model,” whose size scales with the absorbed photon energy. With larger optical power inducing multiphoton detection regime, the same scaling law remains valid, up to the three-photon regime. We demonstrate the validity of applying a limited number of measurements and using such a simple model to reasonably predict any SSPD behavior among a collection of nanowire device widths at different photon wavelengths. These results set the basis for designing efficient single photon detectors operating in the infrared (2–5 μm range).
This work was supported by European projects FP6 STREP “SINPHONIA” (Contract No. NMP4-CT-2005-16433) and IP “QAP” (Contract No. 15848).
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Lobanov, Y. V., Tong, C. -yu E., Hedden, A. S., Blundell, R., & Gol’tsman, G. N. (2010). Microwave-assisted measurement of the frequency response of terahertz HEB mixers with a Fourier transform spectrometer. In Proc. 21th Int. Symp. Space Terahertz Technol. (pp. 420–423).
Abstract: We describe a novel method of operation of the HEB direct detector for use with a Fourier Transform Spectrometer. Instead of elevating the bath temperature, we have measured the RF response of waveguide HEB mixers by applying microwave radiation to select appropriate bias conditions. In our experiment, a microwave signal is injected into the HEB mixer via its IF port. By choosing an appropriate injection level, the device can be operated close to the desired operating point. Furthermore, we have shown that both thermal biasing and microwave injection can reproduce the same spectral response of the HEB mixer. However, with the use of microwave injection, there is no need to wait for the mixer to reach thermal equilibrium, so characterisation can be done in less time. Also, the liquid helium consumption for our wet cryostat is also reduced. We have demonstrated that the signal- to-noise ratio of the FTS measurements can be improved with microwave injection.
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Korneev, A., Korneeva, Y., Florya, I., Voronov, B., & Goltsman, G. (2011). Spectral sensitivity of narrow strip NbN superconducting single-photon detector. In J. Fiurásek, & I. Prochazka (Eds.), Proc. SPIE (Vol. 8072, 80720G (1 to 9)). SPIE.
Abstract: Superconducting single-photon detector (SSPD) is patterned from 4-nm-thick NbN film deposited on sapphire substrate as a 100-nm-wide strip. Due to its high detection efficiency, low dark counts, and picosecond timing jitter SSPD has become a competitor to the InGaAs avalanche photodiodes at 1550 nm and longer wavelengths. Although the SSPD is operated at liquid helium temperature its efficient single-mode fibre coupling enabled its usage in many applications ranging from single-photon sources research to quantum cryptography. In our strive to increase the detection efficiency at 1550 nm and longer wavelengths we developed and fabricated SSPD with the strip almost twice narrower compared to the standard 100 nm. To increase the voltage response of the device we utilized cascade switching mechanism: we connected 50-nm-wide and 10-μm-long strips in parallel covering the area of 10 μmx10 μm. Absorption of a photon breaks the superconductivity in a strip leading to the bias current redistribution between other strips followed their cascade switching. As the total current of all the strips about is 1 mA by the order of magnitude the response voltage of such an SSPD is several times higher compared to the traditional meander-shaped SSPDs. In middle infrared (about 3 μm wavelength) these devices have the detection efficiency several times higher compared to the traditional SSPDs.
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