Research On Flexible Polarization-Dependent Color Filters

Compared with the traditional color filters,the use of sub-wavelength filters to achieve color has the advantages of low pollution,high transmission efficiency,and small size.Such devices have potential application prospects in many fields such as display,detection,and imaging.However,the optical performance of the manufactured devices is usually static or changes slowly,which limits the practical application of the device.Flexible devices have the characteristics of being bendable,and foldable,they have attracted more and more attentions in the fields of dynamic display,and flexible sensing.In this work,we combine the advantages of dielectric filters and micro-nano device processing technology to realize a flexible polarization-related color filter based on the dielectric subwavelength periodic structures:Firstly,we give a brief introduce of the basic theory and numerical calculation methods of the subwavelength metasurface structure's effect on electromagnetic fields.The paper analyzes the transmission process of light on the surface of sub-wavelength dielectric structures,such as the generalized Snell's law,the Mie resonance theory,and introduces the finite-difference time-domain(FDTD)algorithm.Secondly,this paper simulates and designs a full-dielectric polarization-type color filter structure based on the Mie resonance effect.FDTD is used to simulate and analyze the influence of the structure size,period,height and other parameters on the transmission and polarization characteristics of the device.Considering the experimental methods,appropriate structural parameters are selected,and exploring the reason for the polarization of the filter,which is,the difference in the distribution of the electric field is the main reason for the change of the transmission spectrum in different polarization modes.Finally,according to the designed filter structure,a flexible polarizing filter is fabricated in this paper.Based on the basic operation process of micro/nano processing,a flexible filter preparation process is designed,the completed device can be removed from the substrate and can be bent.In the laboratory,we set up a test platform to complete the test of the transmission spectrum of the prepared filter.The test results and the simulation results have the same change trend of the polarization angle,indicating that the structure is polarized.At the same time,the transmission spectrum of the filter with various periodic parameters and the generated light spot were measured.The results show that color gamut tuning can be achieved by changing the period and polarization angle.