APPLICATION OF MICROWAVE PHOTONICS IN FIBER OPTICAL SENSORS

Microwave photonics is a new scientific and technical area of research, which was formed as a result of intensive development of such fields as fiber, integrated and nonlinear optics, laser physics, optoelectronics and microelectronics. A positive trend in the field of microwave photonic devices development has appeared in recent decades. The trend is related to the fact that these devices can operate in ultra-high and super-high frequencies and microwave ranges, and have parameters, which are unattainable by conventional electronic devices. Technical characteristics of microwave photonic measuring systems are comparable with those of traditional fiber-optic sensors. This technology can be used both for creation of new measuring devices and improvement of existing other types of measuring systems. This paper presents an analytical review of microwave photonics application technologies in fiber-optic measuring instruments. The general design concept for microwave photonic fiber-optic measuring devices is considered in the first part of the review paper. Microwave photonic filters are presented, which are the key elements of microwave photonic fiber-optic measuring devices. Their design technologies are described with indication of the features, advantages and disadvantages. Methods for creation of microwave photonic finite impulse response filters with positive and negative coefficients are considered. The following sections are devoted directly to the analysis of microwave photonic fiber-optic measuring devices and contain classification of such devices according to their principle of operation. The classification of spectral and interferometric microwave photonic fiber-optic measuring devices with indication of their distinctive features is proposed. Experimental data of the most common sensors is presented and analyzed; the main characteristics and areas of their practical application are presented for each of them. New approaches and methods are considered for creation of microwave photonic measuring systems and improvement of tactical and technical characteristics of existing devices. Comparison between microwave photonic fiber-optic measuring devices and traditional fiber-optic measuring systems is performed. According to comparison results, conclusions can be drawn about applicability of microwave photonic fiber-optic measuring devices and advantages of their use compared to other fiber-optic sensors.