Design of three-primary-color filter based on structure of three-cavity Fabry–Perot color filter

Abstract

In order to possess narrow passband and high transmittance at the center wavelengths of three primary colors, a three-cavity Fabry–Perot (FP) color filter is proposed whose center wavelengths are 700 nm (red), 546.1 nm (green) and 435.8 nm (blue) respectively. Through simulation, it is found that when the green color filter is in the middle, the transmission peaks only appear at the wavelength of three primary colors in the visible light range. And the structure of green color filter in the middle is designed as $$\left( {LH} \right)^{6} 2L\left( {HL} \right)^{6}$$ while the structure of red and blue color filters on both sides is $$\left( {HL} \right)^{6} 2H\left( {LH} \right)^{6}$$ to avoid high transmission peaks other than the center wavelengths of three primary colors caused by the 2H half-wavelength layer at the junction after combination. On this basis, the film thickness has been optimized to improve the transmittance at the wavelengths of the three primary colors and suppress the transmittance at other wavelengths. Through simulation analysis, it can be seen that the transmittance of the improved filter with optimized film thickness reach 99.64%, 96.77% and 92.94% at the wavelengths of 700.6 nm, 545.8 nm and 434.8 nm, and the full width at half maximum (FWHM) are 2.1 nm, 4.5 nm and 3.1 nm respectively. Compared with a three-primary-color filter based on grating structure, photonic crystal and metal film plasmonic, the three-cavity FP color filter proposed in this paper has not only higher transmittance at the center wavelengths of three primary color but also very narrow FWHM, which is 1–2 orders of magnitude lower than the former. Due to its superior performance, simple structure and convenient design, the filters of this structure are expected to be widely applied in display technology, color synthesis and modulation.