Optofluidic ring resonator based dye laser

The authors demonstrate a microfluidic dye laser using a liquid core optical ring resonator (LCORR). The LCORR is made of a fused silica capillary with a wall thickness of a few microns. The circular cross section of the capillary forms a ring resonator that supports whispering gallery modes (WGMs) and provides an optical feedback for lasers. Due to the high $Q$ factor of the WGM $\left({10}^7\right)$ , a low lasing threshold is achieved $(1\mu \mathrm{J}∕{\mathrm{mm}}^2)$ . In addition, they show that the laser can be coupled out via a tapered fiber in touch with the LCORR, thus providing a mechanism for easy laser delivery.