tunable multimode plasmonic filter based on side-coupled ring-groove joint resonator

A tunable multimode plasmonic filter is proposed by using a side-coupled ring-groove joint resonator. in addition to the integer resonance modes of the perfect ring resonator (rr), extra non-integer resonance modes are excited by adding a groove on the rr. according to the simulations with finite difference time domain method, it is investigated that two integer and two non-integer modes are obtained. when the groove is placed on the antinodes of the magnetic fields, the effective resonance lengths for the corresponding modes will be changed by the groove. in this case, one can linearly manipulate the wavelengths by changing the length of the groove. on the contrary, the wavelengths of the specific modes will be always fixed when the groove locates at the nodes of the modes. compared to those perfect structured fabry-pérot (fp) resonators, this compact device can provide more channels and manipulate the wavelengths flexibly. therefore, it find widely applications in the on-chip optical signal processing area.