Thermo-optic coefficients of LiNbO_3, LiIO_3, and LiTaO_3 nonlinear crystals

Thermo-optic coefficients (dn/dT) determine the temperature characteristics of nonlinear-optical laser devices. These coefficients are analyzed critically by use of a new model for what is to the author's knowledge the first time to find refractive indices at any operating temperature and wavelength for pure stoichiometrically grown LiNbO(3), LiIO(3), and LiTaO(3) crystals. This model is based on the thermal expansion coefficient, the temperature coefficient of the excitonic band gap, and a newly introduced isentropic band gap that lie in the UV region instead of on consideration of the spontaneous polarizability.