UV-curable adhesive microsphere whispering gallery mode resonators

We report the fabrication and optical characterization of spherical whispering gallery mode (WGM) resonators made from ultraviolet (UV)-curable adhesive. The fabricated microspheres have good sphericity and surface smoothness, and can directly adhere to the tip of half-tapered fibers for easy manipulation. WGMs are efficiently excited in the microsphere using an evanescent field of the tapered silica optical fibers. Resonances with quality factors of 1.3 \times 105 are observed. The dependence of wavelength shifts of WGM resonances on the input light powers shows that the resonant wavelength of the proposed microsphere resonators can be tuned thermo-optically.