Figure 4: Spectra of a microfluidic dye laser
Optical pumping the microlaser with a 532-nm frequency-doubled Nd:YAG laser at 50 Hz results in the bandwidth decrease by an order of magnitude at laser threshold. The sharp increase in output-vs.-input power slope provides further evidence of lasing. The fluid waveguide laser is readily tunable by continuously varying the composition of the mixed solvent (methanol-dimethylsulfoxide) while using the same concentration of the dye.