Fiber optical interferometers are widely used as the sensing elements for measurements of temperature, electric and magnetic fields, acoustic and seismic waves, applied strain etc, because of its high sensitivity, large dynamic range, and convenience for multiplexing [1]. The output of an interferometer is a cosine function of the phase difference between two arms. The phase difference drifts because of the low frequency random temperature and pressure fluctuations, which interferometer arms

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... erience. The drift causes random changes in the detected signal, which are called signal fading. To reduce signal fading several demodulation schemes have been developed. The homodyne detection scheme using phase generated carrier (PGC) exhibits high efficiency, and good linearity, that makes this technique very attractive. In the PGC demodulation scheme, a highfrequency carrier is required to modulate an interferometer. So the key element in this approach is an optical phase modulator for generation of the high frequency carrier. We have developed and fabricated a multifunctional integrated optical scheme (MIOS), which can be used in the PGC demodulation system. The scheme includes three optical components on the one substrate: the optical polarizer, X–coupler, and electrooptical phase modulator.