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

摘要

We report on fabrication of whispering-gallery-mode microlasers in a Nd:glasschip by femtosecond laser three-dimensional (3D) micromachining. Mainfabrication procedures include the fabrication of freestanding microdiskssupported by thin pillars by femtosecond laser ablation of the glass substrateimmersed 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 temperaturewith a continuous-wave laser diode operating at 780nm. This technique allowsfor fabrication of microcavities of high quality factors in various dielectricmaterials such as glasses and crystals.