| Recent advancements in nanofabrication methods and synthesis allow usto arrange nano-holes into array as designed which leads to unusual physicaland chemical properties. Ebbesen et al realized a seminal experiment on lighttransmission through arrays on Ag film. It causes the widely interest thatmetal seems to be more transparent at certain wavelength which challengesour intuition. This opens a new territory of Raman scattering and sensing.Typical nano hole and nano disk-like arrays have been fabricated on metalsubstrate to enhance the Raman signal and instinct fluorescence. Themolecules in subwavelength region responding to the localized field ofsurface plasmon resonant (SPR) can be detected in low concentration. Sucharrays have been suggested to develop into zero-mode waveguide forpolymerase dynamic activity. It can also serve as a SPR sensor since theexcitation of SPP is sensitive to the dielectric constant of the cladding. Theminiaturization resulting from the totally small scale, normal incident modeinstead of Kretschmann configuration and the stability of metal offers anapproach to commercial biological sensing chip concept. In this paper, we introduced the property of surface plasmon polariton andlocalized surface plasmon. We focus on the dominant periodic structure underthe coupled mode theory. We demonstrate the feasibility of EOT on TE mode.And an attempt to all optical switch has been made.Further, we reported a systematical study of a rectangular patternedbull-eye array to explore the intensive electromagnetic field arising up bySPR. The contribution of the enhanced emission of excited-stated molecule isalso taken well regard. After taking the angular distribution improved by thedirectional emission effect into account, a total EF on the orders of106hasbeen assumed. Further, it is presented that the experimental results of Ramanspectrum of4different DNA base molecules. At last, the polarizationdependent performance has been observed implying the origin from dipoleoscillations. The goal of this study is to lay the groundwork for nano-holeenhanced Raman scatterings without the use of extrinsic fluorophores. Itproposes a potential technology to DNA identification and sequencing. |
