Transmission type color filter incorporating a silver film based etalon

Abstract

Transmission type color filters based on a thin film Ag-SiO(2)-Ag etalon were built on a quartz substrate, enabling the infrared suppressed transmission and large effective area. They were designed by taking into account the influence of the dispersion characteristics and the thickness of the silver metal. Three different color filters were devised: The cavity length for the red, green and blue filter was 160 nm, 130 nm, and 100 nm respectively, while the metal layer was fixed at 25 nm. The observed spectral pass band was centered at 650 nm, 555 nm, and 480 nm for the red, green, and blue device; the corresponding bandwidth was about 120 nm, 100 nm, and 120 nm; and the peak transmission was all ~60%. For the oblique light incidence the angular dependence of the peak relative transmission was measured to be approximately 1%/degree. The spectral response of the device was also analyzed for two different polarizations as the tilt angle varied up to 12(o), and it was found to be hardly polarization dependent. Finally, as for the positional dependence the relative transmission and the center wavelength were found to vary within 10% and 5 nm respectively over an effective area of 4x4 cm(2).

Color filters featuring high transmission efficiency and broad bandwidth based on resonant waveguide-metallic grating

“…1, the analyses consider that the waveguide layer has a refractive index (n 1 = 2.4 of ZnS) higher than that of the surrounding media (i.e., n 1 N n I , n II ) to achieve the GMR [13]. In this study, only aluminum (Al) or silver (Ag) is chosen as the calculated metal of the grating layer due to their common uses in the color filtering devices [2,6,7,9]. Accordingly, their dielectric function (ε) derived from the Lorentz-Drude model [14] is evaluated herein.…”

“…As a result, various numerical and experimental studies regarding many types of color filters utilizing one-dimensional (1D) and two-dimensional (2D) subwavelength grating (SWG) structures have been conducted [1][2][3][4][5][6][7][8][9]. An SWG whose period is smaller than the wavelength of the incident light does not generate high diffraction orders.…”

“…The color filters utilizing 1D grating structures, as those considered above [1][2][3][4][5], still exist in multiple sub-peaks, transmission sidebands and narrow bandwidths. Recently, Yoo and Lee [6] presented a 1D transmission color filter based on a thin film Ag-SiO 2 -Ag, of which output colors can be obtained by taking different thicknesses of an oxide (SiO 2 ) thin film, and attained a FWHM of 110 nm and a peak transmission of 57%. However, they have a very high sideband transmission (around 40%) away from the central wavelengths.…”

“…In the studies above, the authors considered the color filters based on 1D and 2D SWG structures in achieving the high transmission efficiency and broad bandwidth. Compared with the 2D grating structures [7][8][9], the 1D ones [1][2][3][4][5][6] have the simpler fabrication process and higher transmission efficiency but more sub-peaks and narrower bandwidths. Moreover, the feasibility of realizing 1D transmission type color filters with the high transmission, large bandwidth, and suppression of redundant sub-peaks and transmission sidebands was not realized completely.…”

Highly Angle-tolerant Spectral Filter Based on an Etalon Resonator Incorporating a High Index Cavity

“…So far, spectral filters based on multi-layered films have been actively attempted, because of their simple structure and low cost [4,5]. However, their performance in terms of center wavelength and transmission efficiency has been critically dependent on the angle of the light beam [6][7][8][9][10], which is widely regarded as a paramount issue with a spectral filter used for receivers, which are applied to free space optics and image sensors. A device tapping into a complicated photonic crystal structure was also suggested, to alleviate the angular dependence [11][12][13].…”