Research On Electrowetting Display Based On Bilayer Metallic Nanowire Gratings

With the development of Plasmonics and Nano-Processing technology,a variety of peculiar characters based on metallic nano-structures are revealed and applied in several fields. The coupling oscillation between electromagnetic field and electrons on the metal/dielectric interface-surface plasmon resonance(SPR) is the main mechanism of those functions. In recent years, with the huge potential in the application of energy-efficient display devices, by using the subwavelength periodic metallic structure to realize color filters and polarizers has been a hot point among industrial companies and academic institutes. So far, investigation of the metallic nano-structures are mostly focused on the passive components. In our work, we make a further step to fulfill active plasmonic devices by combining SPR based on bilayer nanowire metallic gratings(BMNGs) and electro-wetting effect, taking the advantage that SPR resonance is sensitive to ambient refractive index. A full-color transmissive display device with tunable color and brightness via active SPR has been demonstrated. Such a display device shows high contrast, wide color rendering and compact structure, implying a mainstream technology of electronic paper display. The main research works are listed as below:The first part is the theoretical background of SPR including the basic concept of surface plasmon dispersion, phase matching conditions and optical structures to excite SPR. We emphasize on the excitation of SPR by metallic nanowire gratings where the influence of grating parameters on the efficiency of SPR are studied.Secondly, in order to obtain the proper grating structures utilized in fullcolor display devices, the rigorous coupled wave analysis(RCWA) was employed to analyze the spectra. Three pitches of BMNGs, corresponding to sub-pixels of red, green, and blue were designed. The switching characteristic of the devices from bright state to dark state were explored with the increase of ambient refractive index. Then, the samples were fabricated using laser interference lithography and e-beam deposition with measured spectra matching to the simulations. Furthermore, by adding liquid on the BMNGs, light switching from bright to dark was achieved. Therefore, the feasibility of active plasmonic display based on BMNGs was demonstrated.Finally, we studied surface property of BMNGs by building up our own electro-wetting test platform. It is revealed that the surfaces of BMNGs are hydrophobic meaning the feasibility of restorability in electro-modulated wetting. Thus device structures of the sub-pixels are proposed, which paves a way for further investigation.