Study On The Design Of Aperture Coupled Semi-circular Cavity MIM Structure Filter Based On The Surface Plasmon Polaritons

The twenty-first Century is the age of information and multimedia,where people's demand for transmission capacity,rate,bandwidth of information and device miniaturization is getting higher and higher.This situation has promoted the development of microelectronics(Integrated Circuits,IC)and integrated optical technology,but on the other hand,their developments are facing the ultimate challenge at the same time.The presentation of surface plasmon polaritons and the development of nanotechnology make this problem turn out and provide a possible way for the perfect match of electronic circuits and photonic circuits,and the integrated optoelectronic circuit is expected to be realized.The filter based on the surface plasmon polaritons has important application values in the integrated optoelectronic circuit and optical communication system.In view of the low coupling efficiency of the filter based on side coupled and direct coupled method,the aperture coupled method is used to construct the surface plasmon polaritons filters in this paper.First,an asymmetrical semi-circular cavity structure filter is proposed.The magnetic fields,transmission spectrums,bandwidth and edge steepness distribution curves of the filter are obtained by using the numerical simulation software COMSOL Multiphysics 5.2 based on the finite element method(FEM).The results show that the filter has the characteristics of multi-function,easy adjustment and so on.The passband and stopband of this filter all has a wide bandwidth.Its passband transmission ratio is up to 0.95.Its stopband has a good flat characteristic and the transmission ratio is approximate to 0.After optimizing the structure parameters,the filter can realize a similar function of the rectangular filter and the filtering function of channel selection of the three optical communication windows(850nm,1310 nm,1550nm)at telecommunication regime.Then,in order to further expand the filter's filtering performance,two improved structure have been proposed.Next,considering that the asymmetric semi-circular cavity filter has a small steepness of the transmission spectrum,a symmetric semi-circular cavity filter is constructed on the basis of the asymmetric semi-circular filter.The steepness of the transmission curve of the filter is greatly improved compared with the symmetrical semi-circular cavity filter.Similarly,in order to further improve the filtering function of this filter,the structure of the filter is optimized and improved,and a single function(band-pass)filter is obtained.The excellent performance of this series of filters would have a prospective application in micro-nano integrated optical devices,especially in optical communication systems.