Figure 3: A microfluidic dye laser
We used microfluidic technology to design a miniaturized waveguide dye laser, in which the laser cavity contained a liquid core-liquid cladding waveguide. The key feature of the laser is a long optical path length along the waveguide axis that allows us to achieve high gain in one pass and thus lower the threshold for lasing. By coating gold on the surfaces of the T-junctions, we built laser mirrors into an L2 liquid waveguide light source. Rhodamine 640 perchlorate dissolved in methanol served as the core stream, and pure methanol worked as the cladding stream.