Double emulsion optofluidic microlasers

Double emulsion droplets have found diverse applications in biosensing, chemical synthesis, drug delivery, and highthroughput screening and production. In this work, we demonstrate monodisperse double emulsion optofluidic microlasers with a dye-doped thin shell structure. In particular, robust generation of water-in-oil-in-water (W/O/W) double emulsion droplets in a hydrodynamic flow focusing microfluidic device is demonstrated. With careful arrangement of the three liquid components in the double emulsion, an optical microcavity is formed which supports the whispering gallery modes (WGMs) that locate near the surface of the shell layer. Low-threshold lasing has been achieved in W/O/W double emulsion droplets. Lasing emission from double emulsion droplets with different diameter and different shell layer thickness are characterized on the flow. Due to the high degree of control provided by the microfluidic device, both droplet size and shell layer thickness can be conveniently tuned, and thus the lasing properties. The unique two-phase core-shell structure of the double emulsion droplets provides great flexibility and potential in the development of biosensing platform based on the optofluidic laser system demonstrated in this work, especially in the high-throughput bioanalysis.