Femtosecond laser inscription of nonlinear photonic circuits in Gallium Lanthanum Sulphide glass

TL;DR

This paper demonstrates femtosecond laser inscription of single mode nonlinear photonic circuits in Gallium Lanthanum Sulphide glass, highlighting the fabrication process, material analysis, and nonlinear properties preservation.

Contribution

It introduces a multiscan femtosecond laser writing technique for GLS glass waveguides with low loss and preserved nonlinear properties, advancing integrated nonlinear photonics.

Findings

Successful fabrication of low-loss single mode waveguides in GLS

Nonlinear refractive index properties are preserved after writing

Material analysis reveals the origin of index change

Abstract

We report on femtosecond laser writing of single mode optical waveguides in chalcogenide Gallium Lanthanum Sulphide (GLS) glass. A multiscan fabrication process was employed to create waveguides with symmetric single mode guidance and low insertion losses at 800 nm wavelength, compatible with Ti:Sapphire ultrafast lasers. {\mu}Raman and X-Ray microanalysis were used to elucidate the origin of the laser-induced refractive index change in GLS. Nonlinear refractive index measurements of the waveguides were performed by finding the optical switching parameters of a directional coupler, demonstrating that the nonlinear properties were preserved, evidencing that GLS is a promising platform for laser-written integrated nonlinear photonics.