Optical channel waveguides written by high repetition rate femtosecond laser irradiation in Li-Zn fluoroborate glass

TL;DR

This study demonstrates the fabrication of low-loss optical waveguides in Li-Zn fluoroborate glass using high repetition rate femtosecond laser inscription, analyzing how laser parameters affect waveguide quality and composition.

Contribution

It introduces a method for creating high-quality waveguides in fluoroborate glass with detailed analysis of laser parameter effects and compositional changes.

Findings

Waveguides with 3-6 x 10^-3 refractive index contrast were produced.

Laser repetition rate influences waveguide quality and properties.

B and Zn enrichment observed in guiding regions, F migrates away.

Abstract

Low loss, optical channel waveguides have been successfully produced by high repetition rate, femtosecond laser inscription in a Li-Zn fluoroborate glass (64.9B2O3 + 25Li2O + 10ZnF2 + 0.1Er2O3). High quality waveguides were produced at 500 kHz, 1 MHz and 2 MHz laser repetition rates, showing a refractive index contrast in the range of 3-6 x 10-3 depending on various fluences. Dependence of experimental parameters such as average laser power, pulse repetition rate and writing speed on the properties of fabricated waveguides has been discussed. The comparison of optical and compositional characterization techniques evidences an enrichment of B and Zn in the guiding region, while F migrates to the heat diffused region of the written structure.