Fabrication and characterization of chiral structures

Abstract

Chiral structures have been widely studied for many years, especially in the area of microwave engineering. Recently, the focus has been shifted to the optical range in view of new aspects in optical properties that could lead to novel applications in optical devices. This thesis reports a rather simple and cost effectively method to fabricate chiral structures using a 1+6-beam (one central and six side beams) optical holographic lithography (HL) method. Spiral-like structures in the sub-micron ranges could be fabricated in photoresists. Three types of chiral structures: rod-like, left-handed and right-handed spiral structures were studied. The samples were characterized by scanning electron microscope (SEM) and optical transmission between two crossed polarizers. Most importantly, the effect of chiral structures on the polarization of light was extensively investigated. Results show a few degrees of the polarization changes could be possible for 1-2 μm thick spiral samples. The change of polarization could be explained qualitatively by a mean filed theory for chiral structures. Our method could serve as a prototype for mass production of chiral (in particular micro-spirals) structures.

Date of Award	2009
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology