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Vetter, A., Ferrari, S., Rath, P., Alaee, R., Kahl, O., Kovalyuk, V., et al. (2016). Cavity-enhanced and ultrafast superconducting single-photon detectors. Nano Lett., 16(11), 7085–7092.
Abstract: Ultrafast single-photon detectors with high efficiency are of utmost importance for many applications in the context of integrated quantum photonic circuits. Detectors based on superconductor nanowires attached to optical waveguides are particularly appealing for this purpose. However, their speed is limited because the required high absorption efficiency necessitates long nanowires deposited on top of the waveguide. This enhances the kinetic inductance and makes the detectors slow. Here, we solve this problem by aligning the nanowire, contrary to usual choice, perpendicular to the waveguide to realize devices with a length below 1 mum. By integrating the nanowire into a photonic crystal cavity, we recover high absorption efficiency, thus enhancing the detection efficiency by more than an order of magnitude. Our cavity enhanced superconducting nanowire detectors are fully embedded in silicon nanophotonic circuits and efficiently detect single photons at telecom wavelengths. The detectors possess subnanosecond decay ( approximately 120 ps) and recovery times ( approximately 510 ps) and thus show potential for GHz count rates at low timing jitter ( approximately 32 ps). The small absorption volume allows efficient threshold multiphoton detection.
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Rasulova, G. K., Pentin, I. V., & Goltsman, G. N. (2019). Terahertz emission from a weakly-coupled GaAs/AlGaAs superlattice biased into three different modes of current self-oscillations. AIP Advances, 9(10), 105220.
Abstract: Radio-frequency modulated terahertz (THz) emission power from weakly-coupled GaAs/AlGaAs superlattice (SL) has been increased by parallel connection of several SL mesas. Each SL mesa is a self-oscillator with its own oscillation frequency and mode. In coupled non-identical SL mesas biased at different voltages within the hysteresis loop the chaotic, quasiperiodic and frequency-locked modes of self-oscillations of current arise. THz emission was detected when three connected in parallel SL mesas were biased into the frequency-locked and quasiperiodic modes of self-oscillations of current, while in the chaotic mode of those it falls to the noise level.
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Vodolazov, D. Y., Korneeva, Y. P., Semenov, A. V., Korneev, A. A., & Goltsman, G. N. (2015). Vortex-assisted mechanism of photon counting in a superconducting nanowire single-photon detector revealed by external magnetic field. Phys. Rev. B, 92(10), 104503 (1 to 9).
Abstract: We use an external magnetic field to probe the detection mechanism of a superconducting nanowire single-photon detector. We argue that the hot belt model (which assumes partial suppression of the superconducting order parameter Δ across the whole width of the superconducting nanowire after absorption of the photon) does not explain observed weak-field dependence of the photon count rate (PCR) for photons with λ=450nm and noticeable decrease of PCR (with increasing the magnetic field) in a range of the currents for photons with wavelengths λ=450–1200nm. Found experimental results for all studied wavelengths can be explained by the vortex hot spot model (which assumes partial suppression of Δ in the area with size smaller than the width of the nanowire) if one takes into account nucleation and entrance of the vortices to the photon induced hot spot and their pinning by the hot spot with relatively large size and strongly suppressed Δ.
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Gershenzon, E. M., Goltsman, G. N., & Ptitsyna, N. G. (1974). Investigation of excited donor states in GaAs. Sov. Phys. Semicond., 7(10), 1248–1250.
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Angeluts, A. A., Bezotosnyi, V. V., Cheshev, E. A., Goltsman, G. N., Finkel, M. I., Seliverstov, S. V., et al. (2014). Compact 1.64 THz source based on a dual-wavelength diode end-pumped Nd:YLF laser with a nearly semiconfocal cavity. Laser Phys. Lett., 11(1), 015004 (1 to 4).
Abstract: We describe a compact dual-wavelength (1.047 and 1.053 μm) diode end-pumped Q-switched Nd:YLE laser source which has a number of applications in demand. In order to achieve its dual-wavelength operation it is suggested for the first time to use essentially nonmonotonous dependences of the threshold pump powers at these wavelengths on the cavity length in the region of the cavity semiconfocal configuration under a radius of the pump beam smaller than the radius of the zero Gaussian mode. Here we demonstrate one of the most interesting applications for this laser: difference frequency generation in a GaSe crystal at a frequency of 1.64 THz. A superconducting hot-electron bolometer is used to detect the THz power generated and to measure its pulse characteristics.
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