Tunable laser emissions in freestanding high-Q polymethylmethacrylate microbubbles

Abstract

A freestanding dye-doped polymethylmethacrylate microbubble laser based on high-Q whispering gallery mode (WGM) is demonstrated. Low threshold tunable laser emissions are observed in microbubbles with different sizes fabricated by a volumetric pipette. The whispering gallery mode laser emissions in the 944 nm diameter microbubble have a low laser threshold of about 15 μJ pulse−1 and a 0.083 nm free spectral range. The smooth wall of the microbubble ensures a high quality factor of approximately 24 120. In addition, 590 nm–610 nm laser emission is achieved by the reabsorption effect of the dye. This work provides an efficient way to implement a freestanding,easily doped and low cost tunable WGM micro-laser.