Electromagnetically induced transparency-like effect in a single polydimethylsiloxane-coated silica microtoroid

We study both experimentally and theoretically the coupling between a fiber taper and two whispering-gallery modes, which are simultaneously excited in a single pilydimethyl-siloxane-coated silica microtoroid system. The transmission spectrum of the fiber-coupled two-mode microresonator shows a sharp electromagnetically induced transparency-like window within the resonant absorption region. This line shape results from destructive interference between two optical pathways associated with two distinct coexisting modes in a single resonator. The sharp transparency peak has great potential applications in light modulation and highly sensitive biochemical sensors.