High sensitivity bulk electro-optic modulator field sensor for high voltage environments

Abstract

An optical electric field sensor is an effective instrument for surveying the electric or magnetic field around a high voltage electrical system. A Mach-Zender interferometer type modulator is generally used in this kind of sensor. The sensor has good sensitivity to electric or magnetic fields, but an unexpected high field could easily destroy the modulator owing to its short electrode separation. A bulk modulator usually has long separation between the two electrodes, which can prevent modulator breakdown, but its sensitivity is usually worse than the Mach-Zender interferometer type sensor. To solve this problem, a Fabry-Perot cavity is used to improve the sensitivity of the bulk modulator type sensor. This work also discusses the optimization of the sensor sensitivity. When the sensor works on the point where a cavity resonance has maximal slope, the proposed sensor has approximately the same sensitivity for sensing a field as the Mach-Zender interferometer type sensor. (C) 2004 American Institute of Physics.