Design Of Subwavelength Metal Grating Filter Based On Particle Swarm Optimization Algorithm

The sub-wavelength grating structure filter device based on micro-nano structure has attracted more and more researchers' attention because of its good optical characteristics and mature micro-nano preparation technology.It is widely used in flat panel display,fiber-optic communication,new energy,biochemical sensors,etc.The field has broad application prospects.Since the metal material itself has dispersion characteristics,the sub-wavelength metal grating makes it possible to realize a broadband color filter device using micro-nano optical technology.The metal grating structure filter can change the characteristics of the peak position and bandwidth of the transmission spectrum by adjusting its own structural parameters.The research content of this paper mainly includes two aspects: on the one hand,it analyzes the surface plasmon resonance and guided mode resonance phenomenon and principle occurring in the subwavelength metal grating structure,and deduces the conditions that need to be satisfied.The Rsoft DiffractionMOD software was used to model and analyze the single-layer metal grating,the metal-dielectric double-layer grating and the metal-dielectric metal three-layer grating structure,and explore the influence of various structural parameters on the transmission characteristics.According to the simulation results,the sub-validation was further verified.The mechanism of transmission anomalies in wavelength metal grating structures.On the other hand,in order to optimize the structural parameters of the device,improve the transmission performance of the sub-wavelength metal grating structure,and achieve high-efficiency transmission of redlight,this paper proposes the particle group optimization(PSO)algorithm to take the period,height and duty cycle of the grating structure as The optimized particles are combined with the rigorous coupled wave analysis(RCWA)algorithm to compare the fitness values of the particles in the particle group.The metal-high refractive index medium and the metal-high refractive index medium-metal grating filter structure are modeled in software.Write an optimization program,iterate over and over again,and find a set of parameters that optimize the transmission performance within a certain range.According to the MATLAB simulation results,the structural parameters,the period is,the metal grating thickness is 0.300?m,the dielectric grating thickness is 0.035?m,and the grating duty ratio of0.77 is transmitted by the metal-dielectric grating with a wavelength of0.65?m.The rate is up to 76%,the sideband transmission efficiency is not more than 15%;the period is 0.312?m,the metal grating thickness is0.017?m,the dielectric grating thickness is 0.47?m,and the transmittance of the metal-medium-metal three-layer symmetric grating structure with a duty ratio of 0.66 to the red light with the wavelength of 0.65?m achieved80%.The light transmittance reaches 80%.These two structures enable efficient transmission of light of a specific wavelength to achieve filtering.This research provides a new method for the design of sub-wavelength metal grating structure,and provides theoretical basis and technical reference for the preparation and practical application of micro-nano structure filter device.