Polarization-insensitive space-selective etching in fused silica induced by picosecond laser irradiation

TL;DR

This paper demonstrates that chirped picosecond laser pulses enable polarization-insensitive, space-selective etching in fused silica by inducing interconnected nanocracks, facilitating efficient microfabrication of 3D microfluidic systems.

Contribution

It introduces a novel laser processing technique using chirped picosecond pulses to achieve polarization-insensitive etching in fused silica, enhancing 3D microfabrication capabilities.

Findings

Polarization dependence of etching rate disappears with chirped pulses.

Chirped pulses induce interconnected nanocracks in fused silica.

Efficient etching maintained despite polarization insensitivity.

Abstract

It is well known that when the fused silica is irradiated with focused femtosecond laser beams, space selective chemical etching can be achieved. The etching rate depends sensitively on the polarization of the laser. Surprisingly, we observe that by chirping the Fourier-transform-limited femtosecond laser pulses to picosecond pulses, the polarization dependence of the etching rate disappears, whereas an efficient etching rate can still be maintained. Observation with a scanning electron microscope reveals that the chirped pulses can induce interconnected nanocracks in the irradiated areas which facilitates efficient introduction of the etchant into the microchannel. The reported technology is of great use for fabrication of three-dimensional (3D) microfluidic systems and glass-based 3D printing.