3D microfluidic lasers embedded in glass by femtosecond laser direct writing

By integrating a series of miniaturized functional components like microfluidics, microelectronics, micromechanics, and microoptics, a lab-on-a-chip device would permit superb performance in chemical and biological analyses with reduction of reagent consumption, waste production, analysis time and labor costs. Since a large part of biological analyses are based on optical means such as photoabsorption spectroscopy or fluorescence detection, incorporating microoptical components into the lab-on-a-chip device is an important issue. However, difficulties in packaging and assembly have been major challenging issues in the manufacture of such devices. Recently, our group developed a technique of fabricating 3D hollow microstructures in a glass chip using femtosecond laser direct writing followed by postannealing and successive chemical etching, facilitating precise, efficient, and cost-effective manufacturing of integration of 3D microfluidics and 3D microoptics. In this paper, we report the fabrication of microfluidic dye lasers embedded in glass by integrating 3D microoptical and 3D rnicrofluidic components. After filling the microfluidic chambers with laser dye rhodamine 6G dissolved in ethanol and pumping the rnicrofluidic lasers by a frequency-doubled Nd:YAG laser, lasing action was confirmed by analyzing the emission spectra at different pumping powers. In addition, by serially stacking two rnicrofluidic chambers in the glass, we built a microfluidic dual-color laser which produces an array of two simultaneous laser emissions at different wavelengths using only one pumping laser. The microfluidic laser array can be easily integrated with an array of microfluidic channels to perform parallel analysis of multiple reactants, thereby not only multiplying the detection speed but also widening the application range for lab-on-a-chip science.