Effect of Host Polymer on Microfiber Resonator

We observe that changing the surrounding material from air to a low refractive index polymer can considerably alter the transmission spectrum of a microfiber knot around a given wavelength. We report on a silica microfiber knot resonator about 180 m in diameter. Using a supercontinuum source, we study its transmission when air and when a low index polymer are used as cladding. The resonator shows similar extinction ratio and Q-factor for both cladding materials. However, embedding the resonator in the polymer down-shifts the optimal operating wavelength by about 20%.