Design And Simulation Of Surface Plasmon Based Functional Devices

In this paper,three functional devices are designed based on surface plasmons:Near-infrared narrow-band band stop filter,Ultra-broad broadband band stop filter and Terahertz broadband absorber.The designed structure is numerically simulated by using the finite-difference time-domain method,and the transmission characteristics of related devices are analyzed in combination with theory.The content of this article is as follows:(1)Near-infrared narrow-band band stop filter: A near-infrared narrow-band band stop filter based on a square cavity is designed and numerically studied using finite difference time domain difference method.The structural parameters of the waveguide,the structural parameters of the square cavity and the influence of the refractive index of the square cavity on the transmission curve are systematically analyzed,and a method to adjust the position of the resonance peak is proposed.This method can change the position of the resonant peak proportionally.Combining this method with the method of changing the refractive index of a square cavity can modulate the position of a specific resonance peak.(2)Ultra-broad broadband band stop filter: A band-stop filter with ultra-broad broadband is designed on the basis of the near-infrared narrow-band band-stop filter waveguide.The influence of the structural parameters of the tooth-shaped protrusions on the transmission curve was systematically analyzed.Combining the electromagnetic field distribution,a theoretical model is established and the influence of different angles of the tooth structure on the resonance wavelength is explained.the phenomenon that the increasing number of the different tooth-shaped structures will lead to the increase of the bandwidth was explained.Based on the above analysis,an ultra-broad broadband band stop filter was designed.It also numerically simulates the process of the gradual increase of the tooth structure and the process of continuously optimizing the structural parameters and number of the tooth-shaped protrusions.(3)Terahertz absorber: A metamaterial broadband absorber in the terahertz band is designed.By covering the base structure with a multilayer structure,the absorptivity of the wave trough can be increased to achieve a completely flat absorption curve,the cause of absorption is analyzed through the electric field and magnetic field distribution at the resonance peak,and numerically simulate the influence of different incident angles on the absorption curve.