Study Of Multi-Ring Band-Stop Filter Based On Surface Plasmon Polaritons

Surface plasmon polaritons (SPPs) are electromagnetic excitations propagating at the interface between dielectric and conductor due to the interaction between the free electrons of the conductor and the induced electromagnetic field. SPPs has many distinctive optical properties, such as enhancement of near field, highly localization and extraordinary optical transmission and so on. It has become the focus of research on near field optic these years. Meanwhile, SPPs also has wide application. Photonic chip, optical filter, optical switch and antenna, nanooptoelectronic devices are all based on the people’s further research. This paper focuses on the optical filter. We design a band stop optical filter with multi-rings and investiagte its optical transmission properties by utilizing finite difference time domain.We first studied the optical transmission characteristics of single ring resonator with its wavelength from700nm to1050nm. The results show:when increasing the radius of the ring, the resonance wavelength will linearly increasing; when adding medium of different refractive index in the ring resonator, the resonance wavelength will also increase with the increasing of the refractive index; when increasing the coupling distance between the channel and the ring resonator, the resonance wavelength will have a slightly blue shift and the full width at half maximum of the transmission resonance spectrum will greatly decrease, the filtering effect will obviously get worse.Secondly, we study the transmission properties of double ring resonators. The results show:when two rings are in same size, no matter two rings are in one side or in both sides of the channel the transmission spectra are the same. Compared with the single ring of same size, the transmission spectra are basicly coincident and just has a broadened. Moreover, the transmission efficiency of the resonance wavelength can be as high as0.02%which is one time higher than the single ring. This means that once the parameters of the structure are given, the resonant mode is determined and the number of the ring resonator has little effection on transmission spectrum. It has a guiding significance to filter wavelengths for us.Finally we design a four ring band-stop filter based which can filter four wavelengths. Our filter may have important application in highly integrated optical circuits.