Study On Color Filters Based On Micro/Nano Structures

Photonic devices based on specific micro/nano structures have wide range of potential applications in fields of display, detecting, imaging, remote sensing, printing and so forth, because of their advantages of good optical properties, good processing compatibility, outstanding integratability. In recent decades, researchers have studied the photonic devices based on specific micro/nano structures widely and deeply, and made a large number of novel and important achievements. Based on these studies, this paper will carry on in-depth research in the key research directions of the recent photonic devices:1. Propose three kinds of angle insensitive color filters based on two dimensional gratings of silicon, metal-dielectric-metal, metal, and study the optical properties, angular performance, color characteristic of these color filters as well as the physical origin of the angle insensitive color filtering through the electric field distribution. The proposed color filter based on subwavelength silicon grating structure can present three primary colors (red, green, blue) with high saturation and luminance. On the basis of the localized surface plasmon resonance, the optical properties of these proposed filters based on subwavelength metal-dielectric-metal grating structure and metal grating structure are independent on the incidence angle, polarization angle as well as azimuthal angle. And the filter based on the metal grating structure can achieve not only the reflective RGB colors but also the transmissive CMY colors, which has great potential in many fields.2. Change the effective refractive index by filling the oxide of high optical constants into the periodic and regular pores of porous alumina membrane so as to fabricate the color-tuning filters. The method can achieve color tuning property in a large colour gamut by simply adjusting the pore size of the porous alumina membrane and the deposition thickness of the high index oxide, which can have potential applications in display, decoration, and so forth.3. Research three kinds of angle insensitive color filters based on Ag/Si/Cr/TiO2 multilayer film, Ag/SiOx/Ag multilayer film, Si/Si3N4 film stack, and study the optical properties, angular performance, color characteristic of these color filters as well as the physical origin of the angle insensitive color filtering by the phase shift and other methods. The proposed color filter based on Ag/Si/Cr/TiO2 multilayer film achieves the angle insensitive color filtering for reflective RGB colors for the first time, which provides the possibility for colorful e-books with reflective display. According to the resonance condition of the metal-dielectric-metal multilayer film structure, we proposed the silicon oxide with the tunable refractive index to excite the resonance covering the whole visible light region so as to realize the transmissive full color. Taking the advantage of the large absorption of the amorphous silicon, the angle insensitive long-pass filter based on Si/Si3N4 film stack can have great blocking property for the blocking wavelengths and small separation for different polarizations.4. Research a reflective polarization beam splitter with spectrum filtering based on one dimensional subwavelength grating structure, which is used for panel display at the angle of 45°, and this beam splitter blocks the TM-polarized light and selectively reflects the TE-polarized light of partial wavelengths so as to present specific color. Various reflective colors for TE polarization can be obtained by simply adjusting the thickness of the dielectric grating layer. This polarization beam splitter with spectrum filtering, which combines the filtering property and the polarizing property, can reduce the component in the panel display to make the internal structure more compact.5. Propose a polarization beam splitter with spectrum filtering based on multilayer film structure for wear display applications and compared with recent beam splitters, this beam splitter can greatly increases energy utilization with no color deviation.6. Propose an omnidirectional visible-near-infrared ultra-broadband absorber based on a compact multilayer film structure. With the help of several absorptive materials with different band gaps and the graded index profile, the average absorption of this absorber can reach up to 98% for 400nm-2000nm region. The proposed absorber can achieve efficient absorption for 400nm-3500nm region, which is the broadest bandwidth among the multilayer absorbers. In addition, this absorber present good incident angle insensitivity. Specifically, the average absorption of this absorber is over 80% even at a large incidence angle (70°).7. Research a multi-narrowband absorber based on subwavelength grating structure, and the absorption bandwidth of multiband is as narrow as ～30nm or less with the absorption more than 96%. The surface plasmon resonance and the fabry-perot resonance both contribute to the multi-narrowband absorption of this absorber.