OPTICAL FUNCTIONAL ELEMENT, SINGLE CRYSTAL SUBSRATE FOR THE ELEMENT, AND METHOD FOR USING THE ELEMENT

摘要

PROBLEM TO BE SOLVED: To highly precisely and uniformly form a polarization inversion struc ture without any optical distortion. SOLUTION: The optical functional element is obtained by forming the polarization inversion structure at the temperature lower than the Curie temperature by using an electron beam scanning irradiation method or voltage application method in a part of a ferroelectric single crystal substrate preparedly using LiNbO3 crystal having 0.95 to 1.01 molar ratio of Li/Nb as the substrate, and the optical functional element controls the light passing through the polarization inversion part. By this method, <=2% propagation loss and <=1×10-4 optical distortion can be obtained without any heat treatment.