Electro-optic behavior of lithium niobate at cryogenic temperatures

The unclamped relative permittivity, , and the Pockels coefficient, , of congruent lithium niobate at a frequency f = 5760 Hz have been determined at low temperatures (7 K < T < 300 K). A He cryostat setup mounted to one arm of an electronically phase-stabilized Michelson interferometer was utilized for the measurement of . A continuous decrease in both parameters was observed as T → 0 K with limiting values of and , respectively.