Tunable Fano-like resonances in a bent single-mode waveguide-based Fabry-Perot resonator

Tunable Fano-like resonances are demonstrated numerically in a single Fabry-Perot resonator made of a bent single-mode waveguide. The resonances are shown to arise from the strong coupling between the fundamental mode of the core and a whispering gallery mode of the cladding. The tuning is realized by changing the bend radius of the waveguide. The influence of all major parameters of the resonator on its transmission and reflection spectra is illustrated and discussed. We believe that the presented results open up a new degree of freedom in designing bent waveguide-based refractometers, as well as other photonics elements utilizing cladding modes in bent single-mode waveguides.