Polarized Light Field Control Based On Dielectric Micro-nanostructure

Micro/nano-structure refers to a single structure designed artificially with micron or nano-scale characteristic dimensions or a complex functional structure arranged in a specific way.Micro/nano-structured optical devices have significant advantages such as high degrees of freedom,rich physical characteristics,and compact size for integration.This dissertation focuses on the design and numerical demonstration of two novel dielectric micro/nano-structured devices based on modulation of polarized optical fields: one is the donut-like photonic nanojet and the other is the polarization-multiplexed metasurface.1.The donut-like photonic nanojet is formed by the dielectric micro-sphere under illumination of the left circularly polarized Lagureee-Gaussian beam with vortex phase.This new type of photonic nanojet focusing field appears as a specific hollow-ring with a full width at half maximum in subwavelength scale.Besides,there is a reverse energy flow in the center of the focal field.The photonic nanojet properties can be flexible tuned by modifying the radius,refractive index,and topological charge of the incident vortex beam,indicating promising applications in the fields of photon trapping and optical micromanipulation.2.We propose a dynamic-phase-only polarization-multiplexing metasurface that consists of three types of polarization-decoupled meta-atoms.Independent modulations of the incident x-and y-linear polarized light phase mutation were achieved by the designed asymmetries of the meta-atoms.We designed two optical devices.One is the metasurface polarized-beam splitter: it can efficiently split the incident x-and y-linear polarized lights into arbitrary transmission directions with different angles,which has great advantages in the field of beam shaping and deflection.The other is polarization-multiplexing metasurface-holography: It can realize different reconstructed images corresponding to orthogonal polarization channels,implying potential applications in the fields of beam shaping,optical information processing,polarization sensing,etc.This study provides a novel method for the design of polarization-multiplexed wavefront-engineering electromagnetic structures for applications in metamaterials and metasurfaces.