Preparation Of Metal Sub-wavelength Structure With Bio-template Method And A Study Of Its Surface Plasmon Optical Properties

Surface plasmons are interested by different researchers from physics, chemistry, materials and biology fields. The recent advances in nano-science have greatly promoted the research work on the construction and characterization of metal structures on nanometer scale. Progress in this field, further promote the study of surface plasmon optics. It enable us to control the SPs, so we can investigate the underlying science of their behaviors and modulate them for some applications. bio-template method is another bionic approach that rise recently. It makes use of the special and complex structures of the biological materials in nature and use it as templates to produce inorganic materials with special structures. This approach is cheap and easy, and it can construct complex structure that lithography and e-beam lithography can't produce.Using the simplicity and cheapness of bio-template method, constructing a sub-wavelength structure and studying its plasmonic optical properties, the attempt of the combination of the two is the background for this research.In this research work, we use butterfly wings as template and produce a silica sub-wavelength grating periodic structure with length scale of micrometer, then sputtering Ag on this structure to cover a ultra thin metal film to get a periodic metal structure. Optical microscopy and Scanning electron microscopy show that samples have good periodic micro-structures, and the periodic constant is about 1μm. A FDTD simulation model is built in order to get the simulated transmission spectrum. And the FDTD simulation all gives a electric field distributions in the structures, which reveals that there is kind of法布里-泊罗resonance happened in the grooves of the grating. Some of the modes couple with the plasma oscillation in the metal film and induce surface plasmon wave, which causes a enhancement of the transmission. The results can be confirmed by other reports on slits and grooves. A practical transmission spectrum test all show this transmission enhancement. This furthermore prove the simulation results.