Effect of asymmetrical nanostructures on detecting the optical rotational properties of large biofilament structures

In this paper, the effect of tapered asymmetrical gammadion on the optical rotational properties and sensitivity detection of biomolecular structures is presented. The asymmetrical structure is made up of gold material on a glass structure and immersed in water. The chirality of the un-rotated array is first determined by measuring the circular dichroism (CD) spectrum. Three modes, arising from Bloch periodic theory and surface resonance mode are observed. Then each asymmetrical gammadion structure is tapered at the arms. Tapering fraction, which define the ratio of tapered end to the untapered end is used for defining the new design. The designs are then fabricated using e-beam lithography and tested using the polarimeter for CD spectra. The spectra show that the three CD modes changes in degree amplitude and wavelength, especially for smaller tapering fractions.

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