Study On The Performance Of Color Polarization Filter

Nanostructured polarized filters devices based on subwavelength gratings have many advantages:firstly,they are sma ll in size and easy to integrate,and are often employed in the optical path to reduce the volume of the entire optical system;secondly,they are simple in structure and easy to process,and can be fabricated by micro-nano manufacturing technology;finally,they have the advantages of high light utilization rate and adjustable bandwidth,making them widely employed in green nano manufacturing printing and security and anti-counterfeiting.In this paper,rigorous coupled wave analysis(RCWA)was employed to analyze the mechanism of light wave resonance in sub-wavelength grating structured color filters.According to the performance requirements of polarization and filter in display and printing field,color polarization filters with different structures were designed.The structure of the designed color polarization filter was simulated and optimized by using the commercialized software of RSoft,and the structure parameters of the three primary color pixel polarizer are carefully investigated.The main research work of this paper was as follows.(1)A color polarizer with metal/dielectric nano grating structure was designed.Compared with the traditional sub-wavelength single-layer metal grating,the new structure proposed in this paper could effectively improve the polarization filter characteristics.The structure was simple,which could be easily fabricated by machining a dielectric grating layer with high refractive index on the original single-layer metal grating.The device structure only allowed the transmission of transverse magnetic polarized light,and people could achieve different colors by adjusting the period parameters in this structure,thereby getting a variety of color rich palette.For the typical three primary colors,the transmittance of blue,green and red polarization filters are 74.7%,87.9%and 84.5%respectively.In addition,the full width at half maximum of the designed tricolor filter was less than 58 nm.Theoretical analysis showed that the enhanced TM polarized light transmission could be attributed to cavity mode and guided mode resonance.(2)A color filter with double metal nano grating structure was designed.The choice of metal material for the structure had a great influence on its color filter performance.In this paper,the double-layer metal grating made of aluminum(Al)and silver(Ag)was calculated and compared.The results showed that the former device had better filtering performance in the blue-green light band,and the transmittance of the polarizer was 68.2%;the other one had better filtering performance in the red light band,and its transmittance could reach 63.3%.(3)This paper focused on the color filtering ability of two different subwavelength grating filters.After studying the influence of geometric parameters on the performance of the filter,we further studied the color saturation and gamut.In order to more intuitively characterize the color filtering ability,we set the color coordinates of light points varying with grating linewidth and grating interval at CIE 1931.The color coordinates of these light spots were then made into color cards,which provided theoretical guidance for the later experimental preparation,and provided a new technical path for the design of new micro-nano structure color devices.