Tunable erbium-doped microbubble laser fabricated by sol-gel coating

TL;DR

This paper demonstrates a tunable erbium-doped microbubble laser created via sol-gel coating, showing potential for compact laser sources and enhanced optofluidic sensing applications.

Contribution

It introduces a novel fabrication method for a tunable erbium-doped microbubble laser using sol-gel coating and aerostatic pressure tuning.

Findings

Achieved 240 pm wavelength tuning with 2 bar pressure.

Successfully fabricated a microbubble laser with erbium doping.

Demonstrated potential for sensing and laser applications.

Abstract

In this work, we show that the application of a sol-gel coating renders a microbubble whispering gallery resonator into an active device. During the fabrication of the resonator, a thin layer of erbium-doped sol-gel is applied to a tapered microcapillary, then a microbubble with a wall thickness of 1.3 $\mu$m is formed with the rare earth diffused into its walls. The doped microbubble is pumped at 980 nm and lasing in the emission band of the Er$^{3+}$ ions with a wavelength of 1535 nm is observed. The laser wavelength can be tuned by aerostatic pressure tuning of the whispering gallery modes of the microbubble. Up to 240 pm tuning is observed with 2 bar of applied pressure. It is shown that the doped microbubble could be used as a compact, tunable laser source. The lasing microbubble can also be used to improve sensing capabilities in optofluidic sensing applications.