Glass-on-Glass Fabrication of Bottle-Shaped Tunable Micro-Lasers and Their Applications

TL;DR

This paper presents a new method for fabricating tunable microbottle-shaped lasers using CO₂ laser melting of doped glass on silica structures, enabling thermal and strain tuning for various applications.

Contribution

A novel glass-on-glass fabrication technique for microbottle lasers with tunable whispering gallery modes demonstrated on a single micron-scale structure.

Findings

Achieved thermo-optic tuning over 70 GHz via gas flow cooling.

Calibrated flow sensitivity with a high of 100 GHz/sccm.

Demonstrated strain tuning of up to 50 GHz.

Abstract

We describe a novel method for making microbottle-shaped lasers by using a CO$_2$ laser to melt Er:Yb glass onto silica microcapillaries or fibres. This is realised by the fact that the two glasses have different melting points. The CO$_2$ laser power is controlled to flow the doped glass around the silica cylinder. In the case of a capillary, the resulting geometry is a hollow, microbottle-shaped resonator. This is a simple method for fabricating a number of glass WGM lasers with a wide range of sizes on a single, micron-scale structure. The Er:Yb doped glass outer layer is pumped at 980 nm via a tapered optical fibre and whispering gallery mode (WGM) lasing is recorded around 1535 nm. This structure facilitates a new way to thermo-optically tune the microlaser modes by passing gas through the capillary. The cooling effect of the gas flow shifts the WGMs towards shorter wavelengths, thus thermal tuning of the lasing modes over 70 GHz is achieved. Results are fitted using the theory of hot wire anemometry, allowing the flow rate to be calibrated with a flow sensitivity as high as 100 GHz/sccm. Strain tuning of the microlaser modes by up to 50 GHz is also demonstrated.