Low-threshold whispering-gallery-mode microlasers fabricated in a Nd: glass substrate by three-dimensional femtosecond laser micromachining

TL;DR

This paper demonstrates a method to create low-threshold whispering-gallery-mode microlasers in Nd:glass using femtosecond laser 3D micromachining, achieving efficient lasing at low pump power.

Contribution

It introduces a novel fabrication process combining femtosecond laser ablation and CO2 laser annealing to produce high-Q microcavities in dielectric materials.

Findings

Lasing observed at ~69 μW pump threshold at room temperature

Fabrication of microcavities with high quality factors

Method applicable to various dielectric materials

Abstract

We report on fabrication of whispering-gallery-mode microlasers in a Nd:glass chip by femtosecond laser three-dimensional (3D) micromachining. Main fabrication procedures include the fabrication of freestanding microdisks supported by thin pillars by femtosecond laser ablation of the glass substrate immersed in water, followed by CO2 laser annealing for surface smoothing. Lasing is observed at a pump threshold as low as ~69 {\mu}W at room temperature with a continuous-wave laser diode operating at 780nm. This technique allows for fabrication of microcavities of high quality factors in various dielectric materials such as glasses and crystals.