基于锚形谐振腔的等离子体波导特性研究

Characteristics of Plasma Waveguide Based on Anchored Cavity

基于表面等离子体激元在金属-介质-金属结构中优良的传输特性,设计了一种由直波导和锚形谐振腔组成的波导滤波器。仿真分析了波导滤波器传输特性和电场分布随结构参数和谐振腔内介质折射率变化规律。结果表明,该锚形谐振腔最佳结构时滤波器半峰全宽低至8 nm,品质因数高达121.9。利用共振波长与结构参数变化规律,设计了光通信波长窗口的窄带带阻滤波器。根据SPPs对谐振腔介质折射率敏感的特性,发现透射谱线随折射率变大而发生红移。本文提出的基于锚形谐振腔的等离子体MIM波导滤波器为设计特定波长的窄带带阻滤波器提供了新思路,也为基于谱线红移特性设计的介质折射率传感器提供了技术支持。

Surface Plasmon Polaritons(SPPs)is a kind of electromagnetic wave propagating along the interface between metal and dielectric.SPPs has the property of confining electromagnetic wave energy in half wavelength region,which can break through the diffraction limit in traditional optics,and is widely used in the design of subwavelength optical devices.In this paper,the Metal-Insulator-Metal(MIM)structure is chosen to excite SPPs.The MIM structure has a wide spectrum range,supports high groupspeed modes at subwavelengths,and enables accurate optical regulation over long distances propagation.In this paper,a MIM waveguide filter based on anchor resonator is designed,the structure is simulated,and the transmission characteristics are analyzed.The simulation results show that the filtering effect at the resonance wavelength changes significantly with the changes of the arc structure angleθ,the rectangular structure height H and the arc structure radius R,and the filtering effect can be precisely controlled by adjusting the corresponding relationship between the parameters fitting data.Because SPPs is sensitive to the refractive index of the medium in the resonator,it can be used to design the refractive index sensor if the anchor resonator is filled with different mediums.In order to explore the influence of structural parameters on waveguide transmission characteristics and further optimize the filter structure,the structural parametersθ,H and R are analyzed,the transmission curve skewing caused by the change of structural parameters is discussed,and the factors leading to the spectral line red shift are expounded.Using the fitting results,high performance narrow band band-stop filters with specific wavelength can be designed.Narrow band bandstop filter is designed based on three windows of multimode fiber.The performance of the three communvication window filters is superior,and the performance is significantly improved compared with other MIM filters.When filtering one window,the normal transmission of the other two windows will not be affected.The communication window selection regulation in optical communication is realized.The sensitivity of the resonance wavelengthλr to the refractive index n of the medium in the anchor resonator is studied.The simulation results show that with the increase of the refractive index n,the resonant wavelength of each mode is red shifted and the transmission curve is changed.The SPPs coupling in MIM structure is sensitive to the refractive index of the medium in anchor resonator,which can be used to make sensing equipment.Compared with the MIM structure of L-shaped resonator,the sensitivity is improved and it is more suitable for designing medium refractive index sensor.In conclusion,a filter based on anchor resonator is designed in this paper.Simulation analysis shows that the structure parametersθ,H and R of anchor resonator can affect its filtering effect,and the narrow band band-stop filtering under the communication window is realized.When the anchor resonator is filled with different mediums,the red shift of transmission spectrum is caused by the increase of refractive index,which provides a theoretical basis for the design of simple dielectric refractive index sensor by using anchor resonator.