Abstract
Microfluidic technology has been widely applied in lab-on-chip because of easy fabrication, low cost and easy manipulation of fluid in microscopic scale. To integrate microfluidics with photonics, we propose and demonstrate microfluidic dye lasers by combining flow-focusing microfluidic channels to generate micro-droplets (laser cavity) with liquid waveguides to couple the light out from the droplet laser. The droplet material is 3mM R6G dye in benzyl alcohol (n=1.54), and the single-mode liquid waveguide is made by mineral oil (n=1.48). We used the finite element method (FEM) to simulate the characteristics of the droplet cavity with different radii and the mode profile of the single-mode liquid waveguide, and used the simulation result to implement the experiment. We designed three different structures to compare the photoluminescence, and verified the lasing modes coupled from the microdroplets to the liquid waveguide. The threshold pump energy for micro-droplet lasing was about 0.32 mJ.