STUDY OF CONTRIBUTIONS TO TEMPERATURE-DEPENDENCE OF THE PHASE-SHIFT IN AN ELECTROOPTIC CRYSTAL

The spontaneous and electric field induced phase retardations have bee n measured as a function of temperature in a KDP crystal using an accu rate method. The plots of these retardations versus temperature reveal unexpected undulations. We consider the various contributions which c ould be involved in these dependences, such as the thermooptic effect, crystal dilatation and temperature dependence of the electro-optic co efficient. By means of calculations, the undulations are shown to be c aused by an interference phenomenon related to light reflections on th e surface of the crystal.