Crystallization of Nonlinear Optical Crystals from Glasses and Their Second Order Optical Nonlinearities

抄録

This paper presents a review for the crystallization of nonlinear optical crystals such as LaBGeO₅, LiBGeO₄, fresnoite-type Ba₂TiGe₂O₈ and several langasite-type crystals in glasses and for the second order optical nonlinearities of those crystals. In this study, transparent surface crystallized glasses consisting of LaBGeO₅, LiBGeO₄ and Ba₂TiGe₂O₈ crystals were successfully fabricated from the corresponding glasses. Second order nonlinear optical coefficients, d₃₃, were evaluated by Maker fringe technique for those surface crystallized glasses. As a result, it was demonstrated that the LiBGeO₄ and the Ba₂TiGe₂O₈ crystals indicated large d₃₃ values, i.e., – 1.3 pm/V and – 22 pm/V, respectively. In particular, d₃₃ of the Ba₂TiGe₂O₈ crystal is comparable to that of LiNbO₃ single crystal. Moreover, we confirmed for the first time that the langasite-type crystals, which are promising materials for SAW device, are formed by crystallization in the corresponding glasses.