Structural Modification in Transparent Ba₂TiGe₂O₈ Crystallized Glasses for a Large Second-Harmonic Generation.

Abstract

Novel transparent crystallized glasses with Fresnoite-type (Ba,Sr)₂TiGe₂O₈ crystals have been successfully fabricated to investigate origin and properties of second-order optical nonlinearity. Glasses with stoichiometric and Sr-substituted compositions of Ba₂TiGe₂O₈ (BTG) crystal, xSrO.(40-x)BaO.20TiO₂.40GeO₂, were heat-treated for crystallization at temperature range of 670-700°C for 3h. Thermal, structural, and optical properties in the crystallized glasses were measured by means of differential thermal analysis, X-ray diffraction method, and Maker fringe technique. As a result, it has been clarified that a transparent crystallized glass with 40BaO.20TiO₂.40GeO₂ composition for BTG has exhibited a large optical second-order nonlinearity, d₃₃=14 pm/V, and a comparison between optical nonlinearity and modification of crystal structure by Sr-substitution was performed to obtain a new photonic glass with larger second-order optical nonlinearity.