A linear electrooptic effect in ferroelectric ceramics: PLZT 12/40/60

Abstract

The transverse linear electrooptic effect found in poled plates of ferroelectric ceramic PLZT 12/40/60 has been utilized in the construction of an optical modulator used for sensing low voltages. The transparency of the La-modified lead zirconate titanate material, the large electrooptic coefficient rc = 1.4 × 10-10 m/V and index of refraction n = 2.55, and the low birefringence at zero field Δn0= -0.0011, make the ceramic convenient for the design of a small optical voltage sensor. This sensor, which is read out using fiber optics, can measure voltages in the range 0-50 V to ± 1 V with a response time of about 0.5 msec. The sensors can be designed to change transmittance by 0.9 %/V. This sensitivity increases considerably with increasing temperature because of concurrent increases in rc and decreases in Δn0. Both this thermal behavior and approximate calculations show rC and thus the large sensor sensitivity, to depend on an electrooptic effect intrinsic to the ceramic material rather than on domain realignment.