2020 |
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Elmanov I, Sardi F, Xia K, Kornher T, Kovalyuk V, Prokhodtsov A, et al. Development of focusing grating couplers for lithium niobate on insulator platform. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 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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Elmanova A, An P, Kovalyuk V, Golikov A, Elmanov I, Goltsman G. Study of silicon nitride O-ring resonator for gas-sensing applications. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 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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Komrakova S, Kovalyuk V, An P, Golikov A, Rybin M, Obraztsova E, et al. Effective absorption coefficient of a graphene atop of silicon nitride nanophotonic circuit. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 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. Silicon nitride Mach-Zehnder interferometer for on-chip quantum random number generation. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 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 IO, Elezov MS, Prokhodtsov AI, Kovalyuk VV, An PP, Golikov AD, et al. Study of microheater’s phase modulation for on-chip Kennedy receiver. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 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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2019 |
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Kovaluyk V, Lazarenko P, Kozyukhin S, An P, Prokhodtsov A, Goltsman G, et al. Influence of the phase state of Ge2Sb2Te5 thin cover on the parameters of the optical waveguide structures [abstract]. In: Proc. Amorphous and Nanostructured Chalcogenides. Technical University of Moldova; 2019. p. 47–8.
Abstract: The fast switching time of Ge-Sb-Te thin films between amorphous and crystalline states initiated by laser beam as well as significant change of their optical properties and the preservation of metastable states for tens of years open wide perspectives for the application of these materials to fully optical devices [1], including high-speed optical memory [2]. Here we study optical properties of the Ge2Sb2Te5 (GST225) thin films integrated with on-chip silicon nitride O-ring resonator. The rib waveguide of the resonator was formed the first stage of e-beam lithography and subsequent reactive-ion etching. We used the second stage of e-beam lithography combining with lift-off method for the formation of GST225 active region on the resonator ring surface. The amorphous GST225 thin films were prepared by magnetron sputtering, and were capped by thin silicon oxide on their tops. The length of the GST225 active region varied from 0.1 to 20 μ m. Crystallization of amorphous thin films was carried out at the temperature of 400 °C for 30 minutes. Auger electron spectroscopy and transmission electron microscopy were used for studying composition and structure of investigated GST225thin films, respectively. It was observed that crystallization of amorphous GST225 film lead to a decrease of the optical power, transmitted through the waveguide. Comparison of the optical transmittance of O-ring resonators before and after the GST225 deposition allowed to identify the change in the Q-factor and the wavelength peak shift. This can be explained by the differences of the complex refractive indexes of GST225 thin films in the amorphous and crystalline states. From the measurement data, the GST225 effective refractive index was extracted depending on the ring waveguide width of the resonator for a telecommunication wavelength of 1550 nm.
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Prokhodtsov A, Golikov A, An P, Kovalyuk V, Goltsman G, Arakelyan S, et al. Effect of silicon oxide coating on a silicon nitride focusing grating coupler efficiency. In: EPJ Web Conf. Vol 220.; 2019. 02009.
Abstract: The dependence of the efficiency of the focusing grating couplers on the period and filling factor before and after deposition of the upper silicon oxide layer was experimentally studied. The obtained data are of practical importance for tunable integrated-optical devices based on silicon nitride platform.
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Zubkova E, Golikov A, An P, Kovalyuk V, Korneev A, Ferrari S, et al. CWDM demultiplexer using anti-reflection, contra-directional couplers based on silicon nitride rib waveguide. In: J. Phys.: Conf. Ser. Vol 1410.; 2019. 012179.
Abstract: We report on the development and fabrication of a 9-channel coarse wavelength-division multiplexing for telecommunication wavelengths (1550 nm) using anti-reflection contra-directional couplers, based on silicon nitride (Si3N4) rib waveguide. The transmitted and reflected spectrum in each channel of the demultiplexer were measured. The average full width at half maximum of the transmitted (reflected) spectra is about 3 nm.
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2018 |
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An P, Kovalyuk V, Golikov A, Zubkova E, Ferrari S, Korneev A, et al. Experimental optimisation of O-ring resonator Q-factor for on-chip spontaneous four wave mixing. In: J. Phys.: Conf. Ser. Vol 1124.; 2018. 051047.
Abstract: In this paper we experimentally studied the influence of geometrical parameters of the planar O-ring resonators on its Q-factor and losses. We systematically changed the gap between the bus waveguide and the ring, as well as the width of the ring. We found the highest Q = 5×105 for gap 2.0 μm and the ring width 2 μm. This work is important for further on-chip SFWM applications since the generation rate of the biphoton field strongly depends on the quality factor as Q3
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Golikov A, Kovalyuk V, An P, Zubkova E, Ferrari S, Pernice W, et al. Silicon nitride nanophotonic circuit for on-chip spontaneous four-wave mixing. In: J. Phys.: Conf. Ser. Vol 1124.; 2018. 051051.
Abstract: Here we present an integrated nanophotonic circuit for on-chip spontaneous four-wave mixing. The fabricated device includes an O-ring resonator, a Bragg noch-filter as well as a nine-channel arrayed waveguide gratings (AWG) operated in the C-band wavelength range (1550 nm). The measured optical losses of the device (-6.8 dB) as well as a high Q-factor (> 1.2×105) shows a good potential for realizing the spontaneous four-wave mixing on the silicon nitride chip.
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