Ferroelectric electrooptic ceramics with reduced scattering

Ferroelectric lead zirconate-titanate ceramics appear promising for use as electrically controlled retarders because both conventional electrooptic and nonvolatile incremental retardation changes can be induced in areas as small as 25 µ on a side. One particular composition, Pb
0.97
La
0.02
Zr
0.65
Ti
0.35
O
3
, has so far proved superior to all other rhombohedral lead zirconate-titanates when judged by either the conventional electrooptic retardation variation with applied bias voltage, or the nonvolatile incremental retardation change with remanent polarization state of the ceramic. Furthermore, this same lanthanum-doped composition exhibits a marked decrease in undesirable light scattering when compared with extensive data on the same composition with bismuth doping. Scattering also decreases with increasing wavelength λ, and the ceramic transmittance is greater than 85 percent for 3 µ<λ<8 µ with sample thickness less than 50 µ. This increased transmittance now makes feasible the construction of multistage ceramic electrooptic systems.