Suppression of bend loss in writing of three-dimensional optical waveguides with femtosecond laser pulses

TL;DR

This paper presents a method to significantly reduce bend loss in 3D optical waveguides written with femtosecond laser pulses, enabling more compact and efficient photonic circuits.

Contribution

It introduces a novel technique of sandwiching waveguides between internal glass modifications to suppress bend loss in femtosecond laser written 3D photonic circuits.

Findings

Bend loss reduced by over ten times with the new method.

Effective for waveguides with a 15 mm bending radius.

Enables more compact 3D photonic circuit design.

Abstract

We provide a solution toward compact and low-loss three dimensional (3D) photonic circuits by femtosecond laser direct writing of 3D waveguides in fused silica. We suppress the bend loss by sandwiching the waveguide between a pair of walls formed by internal modification of glass. Our method allows to reduce the bend loss of a curved waveguide with a bending radius of 15 mm by more than one order of magnitude.