Transverse writing of three-dimensional tubular optical waveguides in glass with slit-shaped femtosecond laser beams

TL;DR

This paper demonstrates the fabrication of tubular optical waveguides in ZBLAN glass using slit-shaped femtosecond laser beams, enabling precise control of waveguide dimensions and mode properties.

Contribution

It introduces a novel transverse femtosecond laser writing technique with slit-shaped beams to create buried tubular waveguides in glass.

Findings

Achieved single-mode waveguides with ~4 μm mode field size.

Controlled the mode area by adjusting the slit-shaped laser parameters.

Demonstrated buried waveguides with variable mode dimensions.

Abstract

We report on fabrication of tubular optical waveguides buried in ZBLAN glass based on transverse femtosecond laser direct writing. Irradiation in ZBLAN with focused femtosecond laser pulses leads to decrease of refractive index in the modified region. Tubular optical waveguides of variable mode areas are fabricated by forming the four sides of the cladding with slit-shaped femtosecond laser pulses, ensuring single mode waveguiding with a mode field dimension as small as ~ 4 {\mu}m.