Plasmonic multi channel filter based on split ring resonators: Application to photothermal therapy

Abstract

In this study, we developed and analyzed a multichannel filter based on multiple plasmonic split ring resonators. In the proposed structure, split ring resonators were coupled to T-shaped and straight waveguides. The field distribution and transmission characteristics were investigated using the finite-difference time-domain method. In the proposed filter, the split ring resonators, and straight and T-shaped waveguides were made of air situated in a silver background. The proposed structure can confine light to sub-wavelength dimensions and it can be utilized in photonic integrated circuits. The results showed that the proposed structure functioned as a typical filter and the electromagnetic wave energy at different wavelengths could be trapped in different insulator rings. The sensitivity factors and dependence of the multichannel filter on the coupling lengths (Li) and ring widths (Ci) were also investigated. Based on the linear relationships with the refractive indices and resonance wavelengths in the ring resonators, sensitivity factors could be obtained for different rings. By increasing the refractive index, the resonance wavelengths exhibited considerable red shifts. The proposed structure with high transmission efficiencies and resonance wavelength ranges (near infrared) will be useful in highly integrated optical circuits, photothermal therapy, and cancer treatment.