Nonlinear optical birefringence in Li2SO4-MgO-P2O5 amorphous system-influence of Cu ions

TL;DR

This study investigates how varying copper oxide content in Li2SO4-MgO-P2O5 glasses affects light-induced birefringence, revealing that lower CuO levels enhance birefringence due to structural modifications.

Contribution

It demonstrates the influence of Cu ions on optical birefringence in these glasses and correlates structural changes with optical properties, providing new insights into material design.

Findings

Birefringence decreases with increasing CuO content.

Low CuO content favors higher birefringence due to structural imperfections.

Electrical and ultrasonic measurements support the structural interpretation.

Abstract

Li2SO4-MgO-P2O5 glasses doped with varied contents of CuO (from 0- 1.0 mol%) were prepared. The optical birefringence induced by a High Q-2 femtosecond pulsed laser is explored as a function of copper oxide concentration in these glasses. The magnitude of the light-induced birefringence exhibited a gradual decrease with the increase of copper oxide content. The observed behavior is discussed in terms of polymerization of the glass network, the degree of which rises with concentration of Cu+ ions occupying Td sites in the glass matrix. However, the samples containing low content of CuO are dominated by Cu2+ ions that act as modifiers and induce structural imperfections by breaking of P-O-S bonds. Accordingly, the samples mixed with lower content of CuO are more favorable for inducing higher magnitudes of the optical birefringence. This conclusion is corroborated by results of electrical conductivity, positron annihilation and ultrasonic measurements.