Design And Fabricate The Color Filter And The Polarizer Based On The Subwavelength Grating

The color filter and the polarizer based on the subwavelength grating have manyunique properties, such as high transmittance and bandwidth adjustable. And they can befabricated with the micro/nano manufacturing technology. They have broad applicationprospects in the future new flat display, green nano-printing, anti-counterfeiting andsecurity, and other fields.In this paper, the resonance mechanism of the subwavelength grating is investigatedby using Rigorous Coupled Wave Analysis (RCWA), aiming at designing thetansmissive-type filter, the reflective-type filter, the absorptive-type filter and the polarizer.Simultaneously, the corresponding devices are fabricated and the performances are tested.The main research works are as follows:(1) Two different polarizers in the visible range are proposed to improve the TMtransmission in the visible range. One consists of a high refractive index dielectric layerinserted between the substrate and the double-layer metallic grating. The TM transmissionin the visible can be improved from67%to73%. The other is the double-layer metallicgratings with air-slots. The TM transmission in the visible range can be greatly improvedfrom67%to85%.(2) The color filters previously reported, which are achieved by adjusting the heightof the metallic grating, are difficult to be fabricated. A novel color filter with a highrefractive index dielectric grating added between the substrate and the metallic grating isproposed. It is clearly demonstrated that the transmission efficiency and the bandwidths areimproved. By adjusting the period of the grating, the red, green, and blue filters areobtained. Compared with the filters without the high refractive index dielectric gratingadded between the substrate and the metallic grating, the peak transmission efficiency of the proposed filters are improved from40%to70%and the bandwidths of the filters areimproved from0.002μm to0.085μm. By adjusting the period of the grating, the red, green,and blue filters can be obtained.(3) Most of the filters based on the subwavelength gratings are very sensitive to theincident angle, which extremely limits the filter device application. Two differentreflective-type wide-angle color filters in the visible range are proposed. One consists of alayer of thick metal, a layer of dielectric film and the metal grating. The other consists ofthe dielectric gratings covered by metal layer. It is demonstrated by the simulation that theposition of the reflection valley and the full-width at half-maximμm (FWHM) remainalmost unchanged when the incident angle is increased to45degree. Their angle-toleranceare superior to the existing filter based on the subwavelength grating.(4) The existing filters based on the subwavelength grating mainly got red, green andblue or cyan, magenta, and yellow colors, but can’t achieve black, which is utilized toadjust the image contrast. A nearly perfect absorption filter structure used in visible rangeis put forward. The absorption of the structure in the visible range is greater than90%andinsensitive to polarization of incident light, which can be used to provide solutions fornano-imprinting to realize the black color.(5) The double-layer polarizer and the reflective-type filter on the PET and Glasssubstrate are obtained using soft nano-imprint approach. The performance test of thedevices verified the validity of the theoretical calculation. The work of this paper ispromised to develop the application of the filter and polarizer based on the subwavelengthgrating. They will provide theory and technology support in the reflective-type flat-paneldisplay, the nano-imprinting without ink and other industries.