Electro-optical composites based on the product of electro-strictive and elasto-optical effects are developed. Layered composites of PbZr1-xTixO3 and polycarbonate are synthesised. Their electro-ptical properties are studied. The nominal transverse electro-optical coefficient of the composite is observed to be about 3.6 times larger than that of LiNbO3. Experiments and theoretical analyses show that the electro-optical effect of the composite has a strong 'size effect'. With the ratio of thickness/length decreasing or the width of elasto-optical phase increasing, the half-wave electric field intensity increases but the transverse electrc-optical coefficient decreases for the layered composite.