Research On Guided Mode Resonance Filter Based On Subwavelength Dielectric Grating

The guided-mode resonance filter has been a great interest in the optical field due to its excellent characteristics,such as extremely narrow bandwidth,high reflection efficiency and almost 0%side-band rejection in a wide range.In addition,the structure is simple,only two or three layers.The guided mode resonance filter based on sub-wavelength dielectric grating structure can satisfy potential and valuable applications in many fields.In this paper,the design and simulation calculation of the guided-mode resonance filter are mainly based on the Rigorous coupled-waves analysis and Effective-medium theory.The electromagnetic field distribution of the guided-mode resonance filter structure is calculated based on Finite-Difference Time-Domain,The characteristics of the guided-mode resonance filter were analyzed based on the electromagnetic field distribution.The main contents of this paper are summarized as follows:1.Outline two basic calculation and analysis theories:Rigorous coupled-waves analysis and Effective-medium theory,the wavelength tunable guided-mode resonance filter in the visible light range is designed based on the Brewster's anti-reflection condition,which can be tuned actively.The position of resonance peak can be tuned by varying the incident angle,we can design a large-range wavelength tunable guided-mode resonance filter in visible light range.2.Based on the equivalent waveguide model of guided-mode resonance filter,the influence of delicate symmetry of structure and material and material refractive index on the spectral response of guided mode resonant filter are analyzed.According to simulation and calculation,the results show that the structural symmetry has an influence on the sideband rejection,and the material refractive index has an impact on the number of resonance peak in visible light range.Then,the desired guided mode resonant filter can be designed faster and better.3.The reflectivity curve of the guided-mode resonance filter under different incident angle is calculated by Rsoft.And we can obtain the variation trend of the resonance wavelength and the full width at half maximum with the incident angle changing.Based on the Finite-Difference Time-Domain,the electromagnetic field distribution of the guided-mode resonance filter in the visible light range is calculated,and the characteristics of the guided-mode resonance filter is analyzed based on the magnetic field distribution of the grating structure under different conditions.The wavelength tunable guided-mode resonance filter is proposed based on dielectric grating in visible light range in this paper,which has better characteristics.On the one hand,the structure is simple,the grating layer is sandwiched between two BaK₅ glass substrates with the refractive index of 1.56,and the resonance peak position of the guided mode resonance filter can be tuned only by changing the incident angle,which realized active regulation,and the wavelength tunable range is nearly 200nm.On the other hand,the excellent characteristics of the reflection spectral can be maintained with changing the incident angle.As the incident angle changes,the reflection spectral is optimized with nearly 100%reflection efficiency,narrow bandwidth less than 0.56nm,wide sideband rejection from 350nm to 900nm,and almost 0%sideband reflectivity,which can satisfy the most requirements of applications for the filters.