Fiber-taper coupling to Whispering-Gallery modes of fluidic resonators embedded in a liquid medium.

We demonstrate efficient coupling to the optical Whispering- Gallery (WG) modes of a fluidic resonator consisting of a droplet embedded in a liquid medium. Unlike previous experiments the droplet is not levitated in an optical or electrostatic trap and free space coupling is replaced by phase-matched, waveguide coupling using a fiber-taper. We have observed critical coupling to fundamental WG modes of a 600 mum diameter water droplet at 980 nm. The experimental challenges towards making, stabilizing and coupling to the droplet resonators are addressed in this paper.