Mueller matrix polarimetry has been used to determine operational efficiency and material quality in lead- lanthanum-zirconium-titanate (PLZT) electro-optic modulators. PLZT is a transparent, quadratic electro-optic ceramic which is a candidate for the next generation of electro-optic interconnects and modulating devices. The Polarimetry group at the University of Alabama in Huntsville has measured Mueller matrices for several sample devices. The purpose of this study was to evaluate the optical quality of the transmissive PLZT devices, determine the uniformity of the modulation across the active area, and calculate the quadratic electro-optic coefficients. High- resolution imaging polarimetry has demonstrated the uniformity of the polarizing and polarization-scrambling properties of a bulk PLZT spatial light modulator array. The Mueller Matrix Imaging Polarimeter was used to produce magnified maps of device regions; this data provides insight to the material uniformity, proper contact of drive electrodes, distribution of the applied electric fields, and quality of the surface. Light scattering from ceramic grain boundaries was also observed to result in some depolarization of light exiting the device. A single-channel Mueller matrix polarimeter measured spatially-averaged device performance for a range of applied operating voltages. This information easily determined the electro- optic coefficients for the modulating material. Several chemical vapor deposited thin-film PLZT devices were studied, and the quadratic electro-optic coefficients compared favorably to that for bulk PLZT.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.