Executive Summary : | Structured light is spatial light shaping with intrinsic features such as amplitude, phase, polarization, and singular structures that fuelled many applications recently. Many important optical tools to control and interact with matter rely on highly focused laser light which generates non-negligible longitudinal (z-axis) electric field component and hence the electric field needs a 3D description. This appearance of longitudinal field components is crucial relevance in light matter interaction and has striking consequences as it confines focusing light to a tighter spot or it may result in complex polarization topologies like mobius strips. Moreover, when the longitudinal electric field component is π/2 out of phase with the transverse components, the light is elliptically polarized in meridional plane and the electric field vector spins around an axis perpendicular to the meridional plane results in transverse spin angular momentum (t-SAM), the so-called photonic wheel. SAM plays important role in spin-orbit interaction (SOI) at sub wavelength (SW) scale leading to promising applications including optical nanoprobing, quantum information technology, spin controlled directional coupling, microscopy etc,. In the recent years, tightly focused vector optical fields with space-variant polarization have been predominantly utilized to tailor spatial and polarization structures of the focal field and only very few studies are dedicated for the behaviour of the energy flux density (EFD) and transverse spin density (TSD) generated by these beams. Such tightly focused inhomogeneous polarized beam, also offers the possibilities of sculpturing desired EFD/ TSD structures in the focal plane, providing an enormous variety of possible landscapes for particle manipulations leading to full control over rotational degrees of freedom in optical traps and in the interaction with chiral matter. These exciting features opens new pathways for optically driven micromachines. Hence there is a stringent demand to engineering focal systems that are simple, tuneable, and flexible to manipulate and steer arbitrary EFD and TSD structures. With the above motivation, this project is dedicated for the theoretical design and optimization of various phase filters (PF) such binary, complex, azimuthal discrete, radial and azimuthal Walsh filters for the input vector Lissajous beams and CV beams with fractional order using Vector Diffraction Theory. The key factor lies in the fact that these beams possess additional degrees of freedom (polarization order, topological charge, and initial phase angle) to flexibly manipulate especially the imaginary part of the longitudinal component and hence the local distribution of Spin and energy flux density. Here we expect utilizing those flexibility and subjecting precise phase modulation through well optimized PFs, offers additional control in the spatial and orientational textures of EFD and TSD in the SW scale focal field. |