Optofluidic evanescent dye laser

We demonstrate the first microfluidic evanescent dye laser which is based on a solid distributed feedback (DFB) cavity and exhibits a pure single mode lasing emission. The laser is composed of a solid second order circular grating DFB cavity and a PDMS chamber filled with dye solution. The thin layer of dye solution served as the liquid cladding covering the whole surface of solid DFB cavity. The evanescent gain is contributed by the interaction between the evanescent tail of the guided wave with the dye solution under optical pumping. As most of the guided mode is located inside the solid waveguide, the guided mode and lasing wavelength selection are primarily determined by the property of the solid DFB cavity. Hence a relatively loose requirement of the refractive index of the dye solution is expected for supporting single mode lasing operation, in comparison with liquid core dye lasers [1].