Laser-tuned whispering gallery modes in microbottle silica resonators based on azobenzene-doped polyvinyl alcohol film

A laser-tuned whispering gallery mode (WGM) microbottle resonator based on ethyl-orange (EO)-doped polyvinyl alcohol (PVA) film is proposed. Due to the photo-induced isomerization feature of the azobenzene material, the WGM resonance wavelength could be tuned by controlling the power density of the lateral pumping laser at 473 nm. Experimental results indicate that the resonance wavelength tunability would generally get strengthened with the increment of the thickness of the PVA film, while it almost remains unchanged under different microresonator diameters. The proposed laser-tuned microcavity integrated with EO is anticipated to find potential applications in tunable optical filtering, optical sensing, and future all-optical network systems.