Spin-Orbit Interaction of Light in Metasurfaces

Suchiang, Harley (2021) Spin-Orbit Interaction of Light in Metasurfaces. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Harley Suchiang (16MS002)) 16MS002_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (8MB)

Abstract

Light has angular momentum which can be categorized into the spin and orbital angular momentum which are related to the polarization and phase structure of light respectively. For paraxial light beams, the inter-conversion between these two types of angular momentum referred to as the spin-orbit interaction of light which can be achieved in anisotropic and inhomogenous medium. Metasurfaces can be tailored to mimic such a medium with sub-wavelength thickness which aid in spin-orbit interaction. We here experimentally show this effect in metasurfaces. To validate our findings we have also simulated the metasurfaces with the help of an FDTD solver. The characterization of the metasurface is done by studying the Muller matrix image to show that it is made up of azimuthally varying diattenuating retarders. Apart from metasurfaces, we have also studied the spin-orbit interaction in non-paraxial light due to tight focusing where the spin-orbit interaction is inherent. We experimentally studied the Muller matrix image due to this effect in the Fourier space which has similar characteristics to the metasurface we have used. This helps us to understand the extent of the spin-orbit interaction due to tight focusing and its effect on the study of metasurface in the Fourier space.

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