Demonstration of microfiber knot laser

Abstract

The authors demonstrate a 1.5μm wavelength microfiber laser formed by tightening a doped microfiber into a knot in air. The 2-mm-diameter knot, assembled using a 3.8-μm-diameter microfiber that is directly drawn from Er:Yb-doped phosphate glass, serves as both active medium and resonating cavity for lasing. Single-longitudinal-mode laser with threshold of about 5mW and output power higher than 8μW is obtained. Their initial results suggest a simple approach to highly compact lasers based on doped microscale optical fibers.