spectral tunability and selectivity based on multiple resonance modes in end-coupled sectorial-ring cavity waveguide

A plasmonic nanodevice in end-coupled sectorial-ring cavity waveguide is reported, and the spectral characteristic of the novel system is studied. it is built with sectorial-ring cavity resonator end-coupled to plasmonic waveguide, and  this resonator is an oversize central angle (θ), alterable symmetry plane angle (ϕ), and fixed radius and gap, which has the advantages of forming split-ring-like, realizing asymmetrical cavity, and achieving spectral tunability and selectivity. the two-dimensional simulation indicates that the extra noninteger and traditional integer resonance modes are excited in the novel system, and the noninteger resonance modes are not achievable for the circular-ring cavity waveguide. it displays that these resonance modes of the novel system are drastically affected by changing the position of ϕ, which has different changes on maximum transmittances but is almost unchanged on resonance wavelengths. importantly, the multiple resonance modes are highly sensitive to ϕ, and the proper modes are significantly enhanced, weakened, excited, or disappeared. it also displays that these resonance modes of the novel system are efficiently affected by changing the size of θ, which has similar and different influences on resonance wavelengths and maximum transmittances. this work shows that the method helps in designing accurately the transmission spectrum with prospective modes in nanophotonics, and the structure facilitates for realization of tunable and selective multichannel nanofilter or nanosensor in integration.