Study On Optical Switch Characteristics Of Subwavelength Metallic Gratings Based On The Principle Of Light Intensity Modulation

The diffraction limit of sub-wavelength slit can be overcome by the sub-wavelength metallic grating,which has excellent polarization and great transmission.The sub-wavelength metallic grating can reduce the number of devices in the optical path,and the sub-wavelength metallic grating is very flexible in the application of the optical system.So the sub-wavelength metallic gratings have the potential to replace and improve the applications of traditional optical components.The transmission properties of sub-wavelength metallic grating is mainly applied in this thesis.The waveguide of optical switch is proposed by the finite element method of vector diffraction theory,and the transmission of metallic grating is physically explained by the equivalent medium theory and F-P cavity theory.In this paper,the switchable control of light is realized by changing the phase value of the transmission wave in the metallic grating.The main works are as follows:First,The transmission of the metallic grating of single layer is calculated by the finite element method of the vector diffraction theory,and the value of the transmission of the TM wave and the TE wave is obtained,and this phenomenon is analyzed by the equivalent medium theory.By changing the parameters of sub-wavelength metallic grating,the transmission of metallic grating is proposed,and we can analyze and explain it by the equivalent medium theory and the F-P cavity theory.Secondly,We observed and analyzed the transmission of metallic grating's waveguide,and explained the change of diffraction phase caused by the abnormal phenomenon of grating Rayleigh.By the equivalent medium theory,the F-P cavity theory,and the Rayleigh phenomenon,the grating's waveguide is explained.It can be concluded that if we can change the refractive index of the grating substrate the modulation of the transmission is proposed.Finally,based on the variation of the diffraction phase on the two sides of the grating,The waveguide structure that sets a layer of electro-optic materials on bothsides of the grating is proposed.The numerical simulation is carried out by the vector diffraction theory,and the waveguide structure that controls the transmission of the grating by the external voltage value is set up.The mathematical model of the relationship between the transmission and diffraction phase is proposed by the F-P cavity and equivalent medium theory.The effects on the optical switch by grating parameters is analyzed by the vector diffraction theory.