Research On Design And Fabrication Of Broadband Sub-wavelength Metal Polarization Grating

Sub-wavelength metal grating is a sort of excellent performance of optical elements.It has special properties which the traditional grating does not have.First it possesses the characteristics of high transmission and extinction ratio,wide spectrum range,great polarization properties.And thensmall volume,compact structure and easily integrated,which made it can reduce the optical components and increase flexibility in the optical systems.Thusit plays an important role in the field of applications of sub-wavelength optical components.It has the potential to improve and replace traditional optical devices.Currently,the theoretical and experimental studies all have shown that the metal grating has big space in application.According to the characteristics of the metal subwavelength polarization grating,this paper launched theory and experiment researches.Mainly includingthe following contents:This paper first briefly presents the development of the analysis theories.On the one hand,weintuitively reflect the principle of polarization properties of the subwavelength metal grating using equivalent medium theory.And mainlyanalyzed the reason for the abnormal enhanced transmission phenomenon in some particular wavelength in the grating transmission spectrum.On the other hand,using simulation software to analyze the influencesto the polarization properties brought about by the multiple parameters suchas the grating period,groove depth,duty cycle,etc.Furthermore,the process of manufacturing grating samples by holographic exposure methodwas explored.We obtained a polarizing beam splitter(PBS)based on two-layer metal grating at near infrared wavelength region in the experiments.The innovation of the structure is that inserteda high refractive-index dielectric layerbetween substrate and grating.Compared with traditional grating,such structure exhibits a greater flexibility of manufacturing,which don't involve in ion beam etching.The diffraction efficiency and extinction ratio on the samples had also been measured and calculated.The results showed that the structure has good performance.