Femtosecond laser writing of electro-optic crystalline structures in glass

Abstract

Over the last decade it has been demonstrated that nonlinear optical (NLO) crystals can be grown by laser precipitation in customized glasses and used for electro-optic applications. It has been further demonstrated that this novel crystal growth technique is capable of fabricating nonlinear waveguide structures, where the polar axis of the crystal is aligned along the growth direction. Femtosecond precipitation of NLO crystals in glass has the potential to be a low-cost method of creating functional optical elements. In order to realize this goal, the orientation of the NLO crystals must be carefully controlled. In the present study, a widely used electro-optical crystal, Lithium Niobate, was precipitated in 33LiO 2 -33Nb 2 O 5 -34SiO 2 (mol%) (LNS) glass, forming NLO crystalline structures in an amorphous matrix. Glass fabrication techniques for making high quality glass, and the crystallization parameter space were explored to determine the optimal conditions for smooth and continuous crystal growth. The crystalline orientation of the precipitated lithium niobate was determined for a variety of writing conditions, and the growth technique was extended to multi-dimensional structures.