McCarthy, A., Krichel, N. J., Gemmell, N. R., Ren, X., Tanner, M. G., Dorenbos, S. N., et al. (2013). Kilometer-range, high resolution depth imaging via 1560 nm wavelength single-photon detection. Opt. Express, 21(7), 8904–8915.
Abstract: This paper highlights a significant advance in time-of-flight depth imaging: by using a scanning transceiver which incorporated a free-running, low noise superconducting nanowire single-photon detector, we were able to obtain centimeter resolution depth images of low-signature objects in daylight at stand-off distances of the order of one kilometer at the relatively eye-safe wavelength of 1560 nm. The detector used had an efficiency of 18% at 1 kHz dark count rate, and the overall system jitter was ~100 ps. The depth images were acquired by illuminating the scene with an optical output power level of less than 250 µW average, and using per-pixel dwell times in the millisecond regime.
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Ferrari, S., Kovalyuk, V., Hartmann, W., Vetter, A., Kahl, O., Lee, C., et al. (2017). Hot-spot relaxation time current dependence in niobium nitride waveguide-integrated superconducting nanowire single-photon detectors. Opt. Express, 25(8), 8739–8750.
Abstract: We investigate how the bias current affects the hot-spot relaxation dynamics in niobium nitride. We use for this purpose a near-infrared pump-probe technique on a waveguide-integrated superconducting nanowire single-photon detector driven in the two-photon regime. We observe a strong increase in the picosecond relaxation time for higher bias currents. A minimum relaxation time of (22 +/- 1)ps is obtained when applying a bias current of 50% of the switching current at 1.7 K bath temperature. We also propose a practical approach to accurately estimate the photon detection regimes based on the reconstruction of the measured detector tomography at different bias currents and for different illumination conditions.
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Martini, F., Cibella, S., Gaggero, A., Mattioli, F., & Leoni, R. (2021). Waveguide integrated hot electron bolometer for classical and quantum photonics. Opt. Express, 29(6), 7956–7965.
Abstract: The development of performant integrated detectors, which are sensitive to quantum fluctuations of coherent light, are strongly desired to realize a scalable and determinist photonic quantum processor based on continuous variables states of light. Here, we investigate the performance of hot electron bolometers (HEBs) fabricated on top of a silicon-on-insulator (SOI) photonic circuit showing responsivities up to 8600 V/W and a record noise equivalent temperature of 1.1 dB above the quantum limit. Thanks to a detailed analysis of the noise sources of the waveguide integrated HEB, we estimate 14.8 dBV clearance between the shot noise and electrical noise with just 1.1microW of local oscillator power. The full technology compatibility with superconducting nanowire single photon detectors (SNSPDs) opens the possibility of nonclassical state engineering and state tomography performed within the same platform, enabling a new class of optical quantum processors.
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Lee, J. - H., Kim, D. - W., Wu, Y. - H., Yu, C. - J., Lee, S. - D., & Wu, S. - T. (2005). High-speed infrared phase modulators using short helical pitch ferroelectric liquid crystals. Opt. Express, 13(20), 7732.
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Stevens, M. J., Baek, B., Dauler, E. A., Kerman, A. J., Molnar, R. J., Hamilton, S. A., et al. (2010). High-order temporal coherences of
chaotic and laser light. Opt. Express, 18(2), 1430–1437.
Abstract: We demonstrate a new approach to measuring high-order temporal coherences that uses a four-element superconducting nanowire single-photon detector. The four independent, interleaved single-photon-sensitive elements parse a single spatial mode of an optical beam over dimensions smaller than the minimum diffraction-limited spot size. Integrating this device with four-channel time-tagging electronics to generate multi-start, multi-stop histograms enables measurement of temporal coherences up to fourth order for a continuous range of all associated time delays. We observe high-order photon bunching from a chaotic, pseudo-thermal light source, measuring maximum third- and fourth-order coherence values of 5.87 ± 0.17 and 23.1 ± 1.8, respectively, in agreement with the theoretically predicted values of 3! = 6 and 4! = 24. Laser light, by contrast, is confirmed to have coherence values of approximately 1 for second, third and fourth orders at all time delays.
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