A Polymeric Platform for Whispering Gallery Modes Silica Microresonators Coupling
Gianluca Persichetti, Vito Coviello, Daniele Farnesi, Gabriele Frigenti, Stefano Pelli, Genni Testa, Gualtiero Nunzi Conti, Romeo BerniniA polymeric platform for high-performance coupling to whispering gallery modes of silica microresonators is proposed and validated. The system is based on a low-refractive-index ridge waveguide fabricated with widely used SU8 and PDMS optical polymers. The waveguide is integrated with grating couplers for a simple fiber-to-chip connection. The coupling capabilities of the proposed platform were characterized using microsphere and microbubble resonators of different sizes. The experimental results demonstrate coupling efficiency in excess of 99% with microsphere and microbubble resonators having intrinsic quality factors in excess of 107 and 106, respectively. This performance is comparable with conventional fiber taper couplers and enables simple on-chip packaging of silica microresonators.