Elmanova, A., An, P., Kovalyuk, V., Golikov, A., Elmanov, I., & Goltsman, G. (2020). Study of silicon nitride O-ring resonator for gas-sensing applications. In J. Phys.: Conf. Ser. (Vol. 1695, 012124).
Abstract: In this work, we experimentally studied the influence of different gaseous surroundings on silicon nitride O-ring resonator transmission. We compared the obtained results with numerical calculations and theoretical analysis and found a good agreement between them. Our results have a great potential for gas sensing applications, where a compact footprint and high efficiency are desired simultaneously.
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Kovalyuk, V., Ferrari, S., Kahl, O., Semenov, A., Lobanov, Y., Shcherbatenko, M., et al. (2017). Waveguide integrated superconducting single-photon detector for on-chip quantum and spectral photonic application. In J. Phys.: Conf. Ser. (Vol. 917, 062032).
Abstract: With use of the travelling-wave geometry approach, integrated superconductor- nanophotonic devices based on silicon nitride nanophotonic waveguide with a superconducting NbN-nanowire suited on top of the waveguide were fabricated. NbN-nanowire was operated as a single-photon counting detector with up to 92 % on-chip detection efficiency in the coherent mode, serving as a highly sensitive IR heterodyne mixer with spectral resolution (f/df) greater than 106 in C-band at 1550 nm wavelength
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Zubkova, E., An, P., Kovalyuk, V., Korneev, A., Ferrari, S., Pernice, W., et al. (2017). Integrated Bragg waveguides as an efficient optical notch filter on silicon nitride platform. In J. Phys.: Conf. Ser. (Vol. 917, 062042).
Abstract: We modeled and fabricated integrated optical Bragg waveguides on a silicon nitride (Si3N4) platform. These waveguides would serve as efficient notch-filters with the desired characteristics. Transmission spectra of the fabricated integrated notch filters have been measured and attenuation at the desired wavelength of 1550 nm down to -43 dB was observed. Performance of the filters has been studied depending on different parameters, such as pitch, filling factor, and height of teeth of the Bragg grating
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Shurakov, A., Mikhailov, D., Belikov, I., Kaurova, N., Zilberley, T., Prikhodko, A., et al. (2020). Planar Schottky diode with a Γ-shaped anode suspended bridge. In J. Phys.: Conf. Ser. (Vol. 1695, 012154).
Abstract: In this paper we report on the fabrication of a planar Schottky diode utilizing a Г-shaped anode suspended bridge. The bridge maintains transition between the top and bottom level planes of a 1.4 µm thick GaAs mesa. To implement the profile of a suspended bridge and inward tilt of a mesa wall adjacent to it, we make use of an anisotropic etching of gallium arsenide. The geometry proposed enables the fabrication of a diode with mesa of an arbitrary thickness to mitigate AC losses in the diode layered structure at terahertz frequencies of interest. For frequencies beyond 1 THz, it is also beneficial to use the geometry for the implementation of n-GaAs/n-InGaAs heterojunction Schottky diodes grown on InP substrate.
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Shurakov, A., Prikhodko, A., Mikhailov, D., Belikov, I., Kaurova, N., Voronov, B., et al. (2020). Efficiency of a microwave reflectometry for readout of a THz multipixel Schottky diode direct detector. In J. Phys.: Conf. Ser. (Vol. 1695, 012156).
Abstract: In this paper we report on the results of investigation of efficiency of a microwave reflectometry for readout of a terahertz multipixel Schottky diode direct detector. Decent capabilities of the microwave reflectometry readout were earlier justified by us for a hot electron bolometric direct detector. In case of a planar Schottky diode, we observed increase of an optical noise equivalent power by a factor of 2 compared to that measured within a conventional readout scheme. For implementation of a multipixel camera, a microwave reflectometer is to be used to readout each row of the camera, and the row switching is to be maintained by a CMOS analog multiplexer. The diodes within a row have to be equipped with filters to distribute the probing microwave signal properly. The simultaneous use of analog multiplexing and microwave reflectometry enables to reduce the camera response time by a factor of its number of columns.
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Titova, N. A., Baeva, E. M., Kardakova, A. I., & Goltsman, G. N. (2020). Fabrication of NbN/SiNx:H/SiO2 membrane structures for study of heat conduction at low temperatures. In J. Phys.: Conf. Ser. (Vol. 1695, 012190).
Abstract: Here we report on the development of NbN/SiNx:H/SiO2-membrane structures for investigation of the thermal transport at low temperatures. Thin NbN films are known to be in the regime of a strong electron-phonon coupling, and one can assume that the phononic and electronic baths in the NbN are in local equilibrium. In such case, the cooling of the NbN-based devices strongly depends on acoustic matching to the substrate and substrate thermal characteristics. For the insulating membrane much thicker than the NbN film, our preliminary results demonstrate that the membrane serves as an additional channel for the thermal relaxation of the NbN sample. That implies a negligible role of thermal boundary resistance of the NbN-SiNx:H interface in comparison with the internal thermal resistance of the insulating membrane.
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Komrakova, S., Kovalyuk, V., An, P., Golikov, A., Rybin, M., Obraztsova, E., et al. (2020). Effective absorption coefficient of a graphene atop of silicon nitride nanophotonic circuit. In J. Phys.: Conf. Ser. (Vol. 1695, 012135).
Abstract: In this paper, we demonstrate the results of a study of the optical absorption properties of graphene integrated with silicon nitride O-ring resonator. We fabricated an array of O-ring resonators with different graphene coverage area atop. By measuring the transmission spectra of nanophotonic devices with and without graphene, we calculated the effective absorption coefficient of the graphene on a rib silicon nitride waveguide.
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Prokhodtsov, A., Kovalyuk, V., An, P., Golikov, A., Shakhovoy, R., Sharoglazova, V., et al. (2020). Silicon nitride Mach-Zehnder interferometer for on-chip quantum random number generation. In J. Phys.: Conf. Ser. (Vol. 1695, 012118).
Abstract: In this work, we experimentally studied silicon nitride Mach-Zehnder interferometer (MZI) with two directional couplers and 400 ps optical delay line for telecom wavelength 1550 nm. We achieved the extinction ratio in a range of 0.76-13.86 dB and system coupling losses of 28-44 dB, depending on the parameters of directional couplers. The developed interferometer is promising for the use in a compact random number generator for the needs of a fully integrated quantum cryptography system, where compact design, as well as high generation speed, are needed.
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Venediktov, I. O., Elezov, M. S., Prokhodtsov, A. I., Kovalyuk, V. V., An, P. P., Golikov, A. D., et al. (2020). Study of microheater’s phase modulation for on-chip Kennedy receiver. In J. Phys.: Conf. Ser. (Vol. 1695, 012117).
Abstract: In this work we describe phase modulators for several Mach-Zehnder interferometers (MZI) on silicon nitride platform for telecomm wavelength (1550 nm). We obtained current-voltage and phase-voltage curves for these modulators. MZI are needed for experimental realisation of various quantum receivers that can distinguish weak coherent states of light with extremely low error. Thermo-optical (TO) modulation is ensured by microheaters on one of the arms of MZI, which enables the change of the refractive index of the material with temperature. This approach allows to apply the necessary voltage to the golden microheaters to obtain the required phase change. For the on-chip microheaters we demonstrate the dependence of the phase shift on the voltage applied to our on-chip microheaters.
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Elmanov, I., Sardi, F., Xia, K., Kornher, T., Kovalyuk, V., Prokhodtsov, A., et al. (2020). Development of focusing grating couplers for lithium niobate on insulator platform. In J. Phys.: Conf. Ser. (Vol. 1695, 012127).
Abstract: In this paper, we fabricate and experimentally study focusing grating couplers for lithium niobate on an insulator photonic platform. The transmittance of a waveguide equipped with in- and out-couplers with respect to the grating period is measured with and without silicon dioxide cladding applied. Our results show the influence of silicon dioxide cladding on the efficiency and the central wavelength of grating couplers and can be used to improve grating coupling efficiency. Our study is supported by numerical simulations.
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