Microfluidic dye laser intracavity absorption

The authors report absorption measurements on low concentration analytes using a microfluidic dye laser. The laser cavity is made of two gold mirrors coated on the end faces of two optical fibers inserted in a chip. Rhodamine 6G dye molecules dissolved in ethanol are used for laser amplification and absorption measurements are done with methylene blue dye solutions. When optically pumped with a frequency doubled Nd:YAG laser at 532nm wavelength, the device shows a laser output emission at 565nm and a high sensitivity of the lasing output to the losses in the cavity, in good agreement with the results of numerical calculations.