Frequency-output fiber-optic voltage sensor for high-voltage lines

We report a frequency-output fiber-optic voltage sensor for high-voltage li nes. The sensor is based on the linear piezoelectric effect of a PZT cerami c tube. A length of single-mode fiber was wound onto the tube and was inser ted in one arm of a Mach-Zehnder interferometer. When an ac voltage is appl ied to the piezoelectric, the interferometer generates a frequency-modulate d signal, which frequency features depend on the applied voltage. The frequ ency-output operation of the interferometer overcomes the interferometer ph ase drift and requires minimum polarization control. Moreover, the output s ignal contains information about the waveform of the applied voltage that c an be reconstructed. We also demonstrate vector addition and subtraction of voltages by using a second piezoelectric.