Modeling of optical circuit and analysis of polarization errors for the reflective optical voltage sensor

The polarization errors of optical circuit limit the accuracy of the quasi-reciprocal reflective optical voltage sensor. The transmission models of discrete optical components and the splice points were developed based on the theory of Jones matrix. Also, a comprehensive transmission model of optical system was derived. The influences of polarization errors on the system performance were analyzed and simulated theoretically. The theoretical and experimental results show that the sensitivity is dependent on factors including the degree of polarization of the light source, the extinction ratio of the polarizer and the azimuth angle between the principle axes of the polarizer and the modulator, the polarization errors induced by which exhibit no influences on the accuracy when the gain of the electrical circuit is large enough. The polarization errors induced by the rotation angle of Faraday rotator, the azimuth angle of the collimator-Faraday rotator with respect to the BGO crystal can mainly result in measurement error, which is sensitive to the environmental changes and brings on the output drift. According to the standard of IEC 60044-7 0.2S, the rotation angle of Faraday rotator and the azimuth angle between collimator-Faraday rotator and BGO crystal should be less than 1.6° and 1.85°, respectively. It is also useful to the design of the optical circuit and the errors compensation of the quasi-reciprocal reflective optical voltage sensor.