Characteristics Feature of Tunable Linear and Circular Dichroism for Applications in Sensing and Imaging

Abstract

Dichroism is one of those natural mechanism of polarization control involved in the absorption of linear polarizations with light transmission. Some crystalline structures having circular dichroism rotate the electric field polarization of the incident light and this property was knows as optical activity. In the cae of linear dichroism it was based on the absorption of linear components, circular dichroism produced an absorption differential between the left and right handed circular polarizations. It was found that circularly or elliptically polarized light were produced from circularly dichroic materials. The circular and linear dichroism are natural ways to control polarized light are based on weak wave interactions. It was found that a variety of polarization states in the reflection spectrum, ranging from pure linearly dichroism behavior to pure circularly dichroism quarter wave plate behavior. The chiral metascreen based on graphene was its reconfigurable frequency response allowed to tune the polarization of the reflected wave to the desired state by varying the Fermi levels. The optical polarization control method was passive and low profile so the device integration at subwavelength scale was achieved. These practical bounds was taken into account the electromagnetic meta surfaces have been an efficient polarization control. The meta surfaces have been fabricated at microwave terahertz and optical frequencies for various applications ranging from perfect absorbers to sensors, thermal emitters and imaging devices. The geometrical chirality rendered a dichroic structure was obtained by etching mirror asymmetric unit cell on the graphene monolayer such that the structure supported the surface plasmon pair when interfaced with a dielectric material. The obtained results were found in good agreement with previously obtained results.