Realization of integrated polarizer and color filters based on subwavelength metallic gratings using a hybrid numerical scheme

Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, Tainan City, Taiwan.
Applied Optics (Impact Factor: 1.78). 02/2011; 50(4):415-26. DOI: 10.1364/AO.50.000415
Source: PubMed


This study realizes integrated polarizer and RGB (red, green, and blue) color filters using single- and multiple-layered subwavelength metallic grating structures. A hybrid numerical scheme based on the rigorous coupled-wave analysis method and a genetic algorithm is used to determine the optimal values of the grating period, filling factor, and grating thickness of three different grating structures, namely, a single-layer grating, a double-layer grating, and a double-layer grating with a lateral shift. The optical performance of the various structures is evaluated and compared in terms of the transmission efficiency at the center wavelengths 700.0 nm, 546.1 nm, and 435.8 nm of red, green, and blue light, respectively, and the extinction ratio over the visible wavelength spectrum (380-780 nm). It is shown that the double-layer grating achieves a transmission efficiency of about 50% and an extinction ratio of around 60 dB. Thus, this grating structure provides a convenient and effective means of achieving the polarizing and filtering functions in LCD panels using a single device.

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    • ", [15], [26], [30]. The obtained results using the OptiFDTD method have been validated with those of previous studies [3], [15], [30]. "
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    ABSTRACT: Double-layered grating structures (DGSs) fabricated of gold (Au) and silver (Ag), respectively, are proposed for chem/biosensing in the midinfrared range. The geometry parameters of the DGS sensors are optimized using a rigorous coupled wave analysis method such that the minimum reflectance is obtained at an infrared wavelength of 4.8 (mu ) or 6.7 (mu ) m. The magnetic field patterns and Poynting vector distributions within the optimized grating structures are examined using a finite-difference time-domain method. The simulation results show that for a resonant wavelength of 4.8 (mu ) m, the Au and Ag sensors both have a sensitivity of 2000 nm/RIU (refractive index unit) and 3000 nm/RIU theoretical sensing resolution of 5 (times 10^{-6}) RIU and of 1 (times 10^{-7}) RIU, respectively. Similarly, for a resonant wavelength of 6.7 (mu ) m, the two sensors have a sensitivity of around 200 nm/RIU and theoretical resolution of 5 (times 10^{-5}) RIU. In other words, the sensitivity of the DGS sensors optimized for an infrared wavelength of 4.8 (mu ) m is one order higher than that of the sensors optimized for a wavelength of 6.7 (mu ) m. In general, the results presented in this paper show that the proposed DGS sensors provide a simple and versatile solution for performing chem/biosensing at midinfrared wavelengths.
    Full-text · Article · Sep 2014 · IEEE Sensors Journal
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    • "Theories and experiments all show that when the period of the grating is close to or smaller than the wavelength of the incident light it always performs strong polarization characteristics. With this feature, we can produce a variety of polarizing devices, such as various wave plates [2], polarizing beam splitters [3–7], and polarizing color filters [8, 9]. On the other hand, the fabrication has been very mature. "
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    ABSTRACT: A new kind of subwavelength metal grating with relief structure is designed and analyzed, in which the shape of the grating lines is no longer a single rectangle, but a relief structure with multiple steps. GsolverV52 was used to determine the optimal values of the grating period, groove depth, and the number of steps. The optical performance of the novel structure is evaluated and compared in terms of the transmission efficiency and extinction ratio over the visible and near-infrared wavelength spectrum. It is shown that, in the near-infrared band, the maximum transmittance can be increased about 15% compared to the traditional metal grating under the same parameters. With the unique characteristics, the metal grating is expected to find applications in liquid crystal display fields, polarization imaging, optical communication, and so on.
    Full-text · Article · Feb 2014 · The Scientific World Journal
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    ABSTRACT: A one-dimensional transmission color filter based on a resonant waveguide-metallic subwavelength grating was numerically investigated by employing rigorous coupled-wave analysis (RCWA) and genetic algorithm (GA). The hybrid numerical method is used to determine the optimal parameters (the grating period, filling factor, grating thickness, and waveguide thickness) of two waveguide-grating structures, namely a double-layer resonant waveguide-metallic grating and a triple-layer resonant waveguide-metallic grating. The optical responses of these structures are evaluated and compared in terms of the ideal transmission efficiency aiming at the central wavelengths of 645nm, 546nm, and 455nm of red (R), green (G), and blue (B) lights, respectively, over the visible region (380–780nm). The results show that the optical performance of the double-layer with silver grating achieves the highest transmission efficiency of 82% (R), 81% (G), and 66% (B); and the largest bandwidth of about 125nm (R), 118nm (G), and 85nm (B). Compared with existing color filters, the proposed device not only obtains a higher transmission and broader bandwidth, but it also suppresses redundant spectral peaks and transmission sidebands.
    No preview · Article · May 2011 · Optics Communications
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