Optofluidic applications using droplet resonators and optical fiber resonators coupled with tapered optical fiber waveguides

Abstract

Sessile microdroplets of water and other polar liquids take almost spherical shapes when standing on a superhydrophobic surface. With their truncated microsphere geometry, they act as optical microcavities hosting whispering gallery modes. We achieved coupling to liquid droplet resonators kept in a controlled humidity chamber with optical fiber waveguides. In these experiments, quality factors exceeding 1 million were observed. A method for self-stabilization of the size of the droplet resonators was also demonstrated using a fixed wavelength heating laser in addition to the probe laser coupled to the same tapered optical fiber. Self-stabilization mechanism relied on the absorption resonances of the heating laser encountered by an initially condensating droplet.