Direct laser-writing of glass-based planar waveguide for fluorescence imaging

Fluorescent microscopic imaging technology has the characteristics of strong labeling capability, high signal strength, low experimental cost, simple imaging process, and imaging from living to in vitro, which is widely used in biological analysis imaging research such as tumor cell imaging, drug distribution in vivo detection, but how to simultaneously have both a wide field of view and a high resolution is a major difficulty in the current field of fluorescence microscopic imaging. Planar silicon waveguides have been found to be able to achieve a wide range of imaging of ultra-thin samples. However, they require sputtering deposition or ion beam etching and other preparation processes. The related processes are complex and equipment required is expensive. In this work, a planar-waveguide-type fluorescence microscope device based on direct picosecond-laser-writing is designed, in which picosecond laser is used to etch the glass surface to rapidly prepare micron sized grooves, and the low-cost and batch-preparation of glass based planar waveguides is further realized by spinning SU-8 photoresist. The waveguide diameter and depth can be customized by adjusting laser processing power, frequency, scanning speed and other parameters. The microscopic detection experiment with using Rhodamine B fluorescent molecule verifies that the direct laser-writing glass based planar waveguide fully meets the requirements for biological imaging with high resolution and large field of view. This simple and rapid processing method can effectively improve the the fluorescence imaging.