Optical Voltage Sensors Based on Integrated Optical Polarization-Rotated Reflection Interferometry

Optical voltage sensors based on reflection interferometry of two orthogonal polarizations have been demonstrated by using a polymeric integrated optic device, in which a thermooptic phase modulator, a polarization converter, and a polarizer are integrated on a single chip. The sensing probe for electric field measurement was prepared by assembling an LiTaO 3 electrooptic crystal along with a polarization maintaining collimator, a Faraday rotator, and a dielectric mirror. Spectral bandwidth of the light source was optimized to be 16.5 nm in order to provide low noise and good extinction ratio in the reflection interferometry. For an applied voltage of 60 Hz, 4 ${\rm kV}_{\rm pp} $ , the sensor exhibited linear response with a phase retardation sensitivity of 0.5°/ ${\rm kV}$ .