DICHROISM OF ELECTROMAGNETIC WAVES USING CHIRAL METASURFACE

Abstract

Metamaterials are materials designed by arranging artificial structures periodically and attained great importance due to its unique Electro Magnetic (EM) properties. Chiral metamaterials show the characteristics of Chirality which is described as if the mirror symmetry for the structure is not validated. Phenomena of Circular Dichroism (CD) is defined as if two EM waves right hand and left hand Circular polarized (RCP & LCP) are transmitted through chiral metasurface but one of the two EM wave can be more strongly absorbed then the other. In this thesis an extremely thin chiral metasurface is fabricated from ‘C-shaped’ metallic design. Specifically, it has great selectivity for incident RCP and LCP EM waves, which is not easily possible in normal metamaterials. The thickness of the chiral metamaterial is 0.8 mm, achieving 63 % efficiency of CD with 200 angular stability. The configuration of proposed Chiral Metamaterial structures is new in literature and are double layered and substrate used is FR-4. Experiments successfully showed that the measured results are in a close settlement with the simulation results. U-shaped ultra-thin chiral metasurface is also designed to achieve efficient CD of 50 % in Ku band having great selection for incident RCP and LCP EM waves with improved band width and angular stability. Thus, these novel designs of chiral metamaterials with great selection for incident RCP and LCP EM waves can expand the research on CD and can be useful in applications including Polar Filters, Stealth Technology and Monitoring changes in antimicrobial peptides or gelatin.