| With the improvements of people' living standard, holography anti-counterfeit technology and holographic packaging have gone deep into people's daily life. However, the existing holography anti-counterfeit technologies are facing challenges from machines such as high precision printer. So, to find a new and effective anti-counterfeit technology for holographic packaging is very necessary.In this paper, a kind of high-precision sub-wavelength gratings are made by micro-nano processing technology. And through the guided-mode resonance effect of the sub-wavelength gratings structure, a visible optical-variable map can be observed, and in this way, anti-counterfeiting achieved. Firstly, the basic principle of guided mode resonance and the method of realizing optical variable image based on guided mode resonance are introduced. Secondly, the mechanism of guided mode resonance in sub-wavelength gratings structure is analyzed. The influence of structure parameters on the wave band and diffraction efficiency of resonance peak of the gratings are studied by using numerical simulations.Thirdly, a full series of processing technic of fabricating the sub-wavelength grating anti-counterfeiting films by using Electron Beam Lithography(EBL) technology, Inductively Coupled Plasma(ICP) etching technology, nano-imprint and electroforming technology is achieved. Fourthly,anti-coagulation layer is coated on the silica substrate and the lifetime of silica substrate is significantly increased. Finally, the fabricated template films are tested and analyzed by using reflective spectrum measurement system. In the end, a visible red-green changeable effect is realized successfully.In this paper A kind of large surface area anti-counterfeiting templates based on sub-wavelength gratings is fabricated successfully. These templates are difficult to be counterfeited since they are consist of high-precision sub-wavelength grating structure and they give obvious red-green color changing effect. |
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