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This thesis summarizes the advantage and versatility of analyzing light-mater interaction exploiting the polarization state of light. We use customized experimental systems to develop specialized techniques to study intriguing optical phenomena at small scales for novel artificial materials. The quintessential parts of this report are Chapter 3 and 4, which describe the experimental results and analysis related to projects covered in this thesis. In the first part of this thesis, we study the case of 3D novel self-assembled carbon flakes with orthorhombic phase of carbon intercalated with bimetallic (Au-Ag) nanoclusters, fabricated from liquid phase solution of a supra molecular complex (SMC) using laser induced deposition process. The fabrication of carbon flakes was done by Prof. Alina Manshina and her group at St. Petersburg State University, Russia. The challenge however, was the small lateral dimensions of individual carbon flakes. Therefore, we developed a scheme (microscopic Müller matrix measurement technique) to extract the optical properties of the carbon flakes, once the incoming and outgoing polarization states of light are known. This technique combines the benefits of polarized light matter interaction with the back focal plane (k-space / Fourier space) microscopy and the usage of electrically controlled liquid crystals to perform a comprehensive polarization analysis in transmission at small scales. With the help of experimental results and theoretical modelling (performed by collaborators at University of Ottawa, Canada), we relate the optical birefringence in the carbon flakes to the crystalline arrangement of carbon atoms in the orthorhombic lattice. Later, we also study the dependence of optical and geometrical properties of carbon flakes on the fabrication parameters. To access the direct information regarding refractive index of the carbon flake, we implement a specialized single-shot ellipsometric technique with a resolution, in the order of the wavelength. This provided us with a preliminary estimate of complex refractive indices of carbon flake. In the second part of this thesis, we focus on the concept of diffraction assisted chiral scattering in 2D metasurfaces. By designing sub-wavelength scattering structures called meta-atoms and periodically arranging them, metasurfaces can be realized with intriguing optical properties. By finely selecting the shape, orientation, material, and size of meta-atoms, their optical response can be tuned. When the meta-atoms are arranged with certain periodicity, it leads to the generation of propagating surface modes, also known as surface lattice resonances (SLR). Resultantly, a resonant coupling of incident light beam with individual meta-atom resonance and grazing diffracted waves can occur. We discuss the in-plane scattering of individual meta-atom and how it could be effectively coupled to the diffraction modes of a lattice to observe asymmetric transmission in the far-fields. We elaborate this concept for a fourfold symmetric structure (quadrumer). The simulations and fabrication were performed in collaboration with researchers from Tecnologico de Monterrey, Mexico and University of Ottawa, Canada (also part of Max Planck-University of Ottawa Centre for Extreme and Quantum Photonics), respectively. For analysis of samples, we use an experimental setup to angularly resolve transmitted light to study asymmetric transmission in zeroth and first diffraction orders. For our case of a fourfold symmetric quadrumer, an in-plane rotation of each quadrumer by 22.5°/-22.5° leads to asymmetric transmission in first diffraction order. The zeroth order does not exhibit any asymmetry. We analyze simulation and experimental results and find them in good agreement. In the outlook chapter of this thesis, we discuss future works related to localized modification of carbon flakes and extension of our ellipsometric scheme using polarization tailored light beams. We also elaborate on few designs/ideas for observing asymmetric transmission in symmetric structures as a future extension of our present work |
