A novel plasmonic device: Filtering and switching functions with quasi-rectangular spectrum based on dual Fano resonances

Compact filters and switches are essential building blocks for performing interference-mitigation and signal -selection in photonic integrated loop. A plasmonic device that exhibits multifunctions including filter and switch is proposed in this paper. The device consists of a hexagonal resonator with rotatable oval core, a stub and two tooth cavities coupled with bus waveguide, respectively. The temporal coupled-mode theory reveals that dual Fano resonances occur in the structure. Finite-difference time-domain method indicates that the bandwidth and transmission of the spectrum can be manipulated by adjusting the parameters of elliptical rotor and stub cavity. Passband ripple is calculated under different structural parameters, and spectrum with low passband ripple of 0.023 dB is realized. Moreover, rotation of the elliptical rotor in the hexagonal resonator will alter transmission spectrum of the output port. Ultimately, filtering and switching functions with quasi -rectangular spectrum are implemented in the designed structure, which will enhance device performance and reduce signal distortion. The fabrication tolerance is analyzed considering widths of stub and tooth cavities. Furthermore, the selectivity of working wavelength at different channels is researched and presented. This novel plasmonic device with low passband ripple has a great impact on improving the quality of signals on chips.

Automated summary

A plasmonic device with multifunctions of filtering and switching is proposed in this paper, achieving filtering and switching functions with reduced signal distortion and low passband ripple. This device has a significant impact on improving the quality of signals on chips.