Electric field-induced birefringence measurements in nuclear detector materials using transmission two-modulator generalized ellipsometry (2-MGE)

It is well-known that internal electric fields can alter the refractive index of certain materials via the Pockels effect. Using the traditional crossed polarizer configuration, this effect has been used to explore internal electric fields in several materials of interest as potential room temperature nuclear detectors. Recently we have shown that the two-modulator generalized ellipsometer (2-MGE) can be configured in the transmission mode, where it measures the retardation, the direction of the principal axis, the diattenuation, and the polarization factor. Therefore, the transmission 2-MGE provides more information and is more accurate than the crossed polarizer configuration. Utilizing various optical schemes, one can sequentially "map" these parameters for a sample. Examples of electric-field-induced birefringence are presented for crystals of LiNbO₃ and CZT.