Emergent Spin-Polarization Optical Effects in Hybridized Nanoscale Optical Systems

Guchhait, Shyamal (2023) Emergent Spin-Polarization Optical Effects in Hybridized Nanoscale Optical Systems. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Shyamal Guchhait (16IP022)) 16IP022.pdf - Submitted Version Restricted to Repository staff only Download (49MB)

Abstract

The thesis deals with two different aspects of optical polarization in the context of the interaction of light with micro and nanoscale optical systems. In the first part of the thesis, various intriguing issues related to the role of classical polarization of electromagnetic waves on the emergence of asymmetric Fano resonances in a special type of hybridized metamaterials, namely, waveguided plasmonic crystal (WPC) have been investigated. Specifically, the role of transverse magnetic (TM) and transverse electric (TE) polarizations of light on the hybridization of the localized plasmon modes and the waveguide modes of the WPC system has been investigated for the application of Fano resonance in sensing. Moreover, the physical origin of giant enhancement of weak magneto-optical effects (Faraday rotation and ellipticity) in waveguided magneto plasmonic crystals (WMPC) has been investigated for incident TE polarized light. The studies unravel an intriguing mechanism of natural weak value amplification (WVA) of the Faraday effect in the WMPC due to the near destructive spectral domain interference of Fano resonance as a dominant mechanism for the enhancement for incident TE polarization. A fundamental relationship between the degree of polarization and the degree of coherence of light has also been established using spectral domain interference of a spectrally narrow and a broad continuum mode leading to Fano resonance and the cross-spectral density matrix of the interfering polarized fields of light. The predictions of the model were experimentally demonstrated in the partially polarized Fano resonance spectra from metal Chalcogenides systems. The second part of the thesis deals with the spin angular momentum (SAM) aspect of circularly (elliptically) polarized light and explores the fundamental effect of spin-orbit interaction (SOI) of light dealing with the coupling and interconversion between the SAM and orbital angular momentum (OAM) degrees of freedom of light. The studies reveal giant spin and orbital Hall effects of light as a consequence of intriguing SOI effects in two different scenarios, that for diffraction of an off-axis vector beam by a tilted aperture and in reflection from epsilon near zero (ENZ) materials. The potential of OAM-carrying vortex beams for imaging through turbid mediums has also been investigated, with early indications showing considerable promise and warranting further explorations.

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