Thermally insensitive design for the LiNbO3 electro-optical modulator under dynamic electric field

The electro-optical crystals exhibit thermally insensitive optic propagation orientations, which satisfy the demand of outdoor industry and military applications. With the aid of wave coupling theory, the temperature stability of the LiNbO3 modulator under dynamic electric field is studied and dynamic thermal insensitive (TI) propagating orientation is sought. It is found that a number of propagation orientations have a dramatically different temperature property when the electric field is varied significantly. The temperature drift of light intensity in specific static TI orientation is raise by 3 orders of magnitude. While for dynamic TI orientation, the effect of the electric field is very limited and the temperature drift of modulated intensity can be controlled below 0.3%. The change of electric field orientation does not influence the temperature characteristics of dynamic TI orientation. An effective method is developed to find the thermally insensitive orientations. And the method is suitable for any type of electro-optic crystal with an applied electric field along arbitrary directions.