Laser printing controllable photonic-molecule microcavities

Abstract Optical microcavity is widely used in high precision sensing and detection fields because of its sensitivity to the environment. Herein, we used femtosecond laser direct writing (FsLDW) to apply PEG-DA hydrogel (polyethylene glycol diacrylate), a polymer material with rapid and significant response to environmental humidity, in fabrication of a whispering gallery mode (WGM) microcavity resonator. Changes in ambient humidity made the cavity expand or contract evenly with stable WGM laser emission. In our experiment, two microcavities spaced 1 μ m apart with a radius of 10 μ m were prepared. Since the volume of the microcavity can be controlled by changing the ambient humidity, the coupling of photonic-molecular microcavities can be intelligently controlled by changing the environmental humidity. The results will inspire further novel ideas about controllable photonic-molecular microcavities.