Modification of borosilicate glass composition for joint thermal processing with lead oxide glasses for development of photonic crystal fibers

Abstract

Development of photonic crystal fibers made of two or more types of glasses can be of considerable advantage in designing of specific properties of photonic crystal fibers. Replacing air holes with a medium with different refractive index provides an additional degree of freedom in fiber dispersion designing. Multi-component oxide glasses can be easily modified by changing the concentration of its ingredients, which in turn changes thermo-mechanical and optical properties of glass. In this paper, we discuss feasibility of joint thermal processing of two types of glasses for photonic crystal fiber drawing. Specifically, we optimize composition of our in-house synthesized high-alkaline borosilicate glass. A series of six- and seven-component glasses synthesized in $$\hbox {SiO}_{2}\hbox {--B}_{2}\hbox {O}_{3}\hbox {--Al}_{2}\hbox {O}_{3} \hbox {--(BaO)--Li}_{2}\hbox {O--Na}_{2}\hbox {O--K}_{2}\hbox {O}$$ oxide system was examined in experiments of combining with commercial lead-silicate glasses F2 and SF6. Joint thermal processing was validated by demonstration of successfully drawn structures of all-solid glass photonic crystal fibers. Critical glass parameters for thermal process of preform fabrication and subsequent fiber drawing, such as thermal expansion coefficient, characteristic viscosity temperatures and crystallization susceptibility were measured, and matched to F2 and SF6 glasses by optimizing composition of borosilicate glasses.