THERMALLY INSENSITIVE, SINGLE-CRYSTAL, BIAXIAL ELECTROOPTIC MODULATORS

All optically biaxial crystals exhibit orientations in which they beha ve as thermally insensitive (TI) wave plates. Given sufficient electro -optic coupling at these orientations, biaxial, ferroelectric crystals may be advantageously employed as single-crystal, temperature-insensi tive electro-optic modulators. I have experimentally confirmed the TI orientation in the principal dielectric plane of the biaxial crystal K TiOPO4 (KTP). KTP behaves as a TI wave plate at 33.7 deg from the Z ax is in the X-Z principal plane. The effective electro-optic coupling, R (eff), at this orientation is 19 pm/V. The electro-optic coupling and utility of these TI orientations in KTiOAsO4 and KNbO3 are also examin ed. The calculated R(eff) of KNbO3 at the TI orientation is expected t o be >2000 pm/V.