(color online) (a) Normalized input lightwave signal and (b) the transmittance spectrum of the filter of Fig. 1. Distributions of the H_z fields in the xy cross section of the filter for three different wavelengths of (c) λ = 6.1 μm, (d) λ = 10.2 μm, resonant wavelengths, and (e) λ = 8 μm, non-resonant wavelength. Only the resonance wavelength of the ring transmits effectively to the output, which shows the filtering effect. Parameters of the ring are set as R₂ = 30 nm and μ_c = 0.35 eV.