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Introduction. Recently, the development of tunable microwave photonic filters has attracted great scientific and practical interest. Such microwave photonic filters are a good alternative to traditional electrical solutions, due to low losses, wide operating frequency range and such filters can be easily integrated into various telecommunication systems. By using an acetylene reference cell and a laser with tunable wavelength can make it possible to create tunable microwave photonic filter with wide operating frequency range.Aim. Investigation of the characteristic of a tunable microwave photonic filter based on an acetylene reference cell, as well as research possible solution to reduce losses in filter bandwidth; numerical simulation of microwave photonic filter characteristics.Materials and methods. Experimental study was carried out on an experimental prototype of a tunable microwave photonic filter. The filter consisted of a laser with a tunable wavelength, a phase modulator, an acetylene reference cell, an optical fiber connecting the gas cell with a photodetector, and a photodetector. Theoretical study was carried out by modeling of the transmission characteristics of the microwave photonic filter.Results. Experimental transmission characteristics of a tunable microwave photonic filter were obtained. The tuning of the filter bandwidth by tuning laser wavelength was studied. Modeling of transmission characteristics of microwave photonic filter was performed. Possible solution to reduce losses in filter bandwidth was proposed.Conclusion. A tunable microwave photonic filter based on an acetylene reference cell is proposed. Losses in the filter bandwidth was about −30 dB. Using high-power laser and a photodetector with a high photocurrent can reduce losses in the filter bandwidth.

Introduction. Optical backscatter reflectometry is one of the most promising methods used to examine characteristic parameters relevant to the design of microring resonators. This method paves the way for experimental determination of the coupling coefficient and propagation loss. However, experimental verification of this technique by comparing the transmission characteristics obtained by reflectometry and those directly measured by an optical vector analyzer has not been carried out.Aim. To determine the parameters of microring resonators by optical reflectometry and to calculate on their basis the transmission characteristics of microring resonators. To compare the calculated transmission characteristics with those obtained experimentally using a high-resolution vector analyzer.Materials and methods. The characteristic parameters of silicon-on-insulator microring resonators were investigated using an ultra-high resolution reflectometer. An original algorithm was employed to derive the characteristic parameters of microring resonators from reflectograms. An optical vector analyzer was used to study the transmission characteristics of microring resonators. Numerical modeling of transmission characteristics considering the obtained parameters was carried out according an analytical approach based on partial wave analysis.Results. The obtained values of the power coupling coefficient κ = 0.167 and propagation losses α = 3.25 dB/cm were used for numerical simulation of the transmission characteristics of a microring resonator. These characteristics were found to agree well with those obtained experimentally. The free spectral range of 88.8 GHz and Q-factor of 45 000 were determined.Conclusion. An experimental study of the characteristic parameters of silicon-on-insulator microring resonators was conducted using an optical backscatter reflectometer. The performed comparison of the experimental and theoretical transmission characteristics showed good agreement, which indicates the high accuracy of the determined resonator parameters and, as a result, the relevance of the described method.

Статья знакомит читателей с принципами создания оптоэлектронных СВЧ-генераторов. В первой части обзора (см. ФОТОНИКА. 2021; 15(3):228–237. DOI: 10.22184/1993-7296.FRos.2021.15.3.228.237) были кратко рассмотрены физические процессы, лежащие в основе работы различных типов генераторов. Во второй части обзора рассмотрены оптоэлектронные СВЧ-генераторы, созданные на основе активных кольцевых резонансных систем, а также проведено сопоставление фазовых шумов оптоэлектронных генераторов различных типов.