Structured Light from Pupil Plane to Focal Field

Date of Award

2020

Degree Name

Ph.D. in Electro-Optics

Department

Department of Electro-Optics

Advisor/Chair

Advisor: Qiwen Zhan

Abstract

It is well known that an optical field consists of phase, amplitude, and the state of polarization (SOP). Spatially customized optical field within the cross section have drawn significant attention recently and expected to lead to new effects and phenomena that can expand the functionality and enhance the capability of optical systems. Under high numerical-aperture (NA) focusing these customized structured lights are expected to exhibit novel phenomena when interact with various type of structured-materials. These interactions may find important applications in super-resolution microscopy, particle trapping and manipulation, materials characterization, as well as three-dimensional high-density optical storage.This dissertation is organized in two parts. In the first part, many different methods to generate complex optical fields using diffractive elements will be reviewed. Among these methods, we will focus on the Vectorial Optical Field Generator (VOF-Gen), which is capable of creating an arbitrary beam with independent controls of phase, amplitude and polarization on the pixel level utilizing high resolution reflective phase-only liquid crystal (LC) spatial light modulator (SLM). Experimental results will be presented, where various optical fields containing phase, amplitude, polarization and retardation modulations are successfully demonstrated.In the second part, focus shaping, three-dimensional (3D) state of polarization and magnetization control, and focusing with spatially variant polarization are investigated and demonstrated. An approach to create diffraction-limited optical focal spots with arbitrarily oriented magnetic dipolar field components in 4Pi microscopy configuration is proposed. This is achieved by focusing two counter-propagating modulated vector beams consisting of complex intensity and polarization distribution. Through combining the magnetic dipole radiation pattern and the Richards-Wolf vectorial diffraction method, the required illuminations at the pupil plane of a 4Pi focusing configuration for the reconstruction of magnetic dipole focal field are found analytically. Furthermore, the orientation of the doughnut shape focal field can be rotated arbitrarily by modulating the pupil field distribution carefully. As an extension, a three-dimensional optical bubble encloses a transversely spinning magnetic field can be obtained by introducing a second magnetic dipole oriented in the orthogonal plane with appropriate amplitude and phase differences.

Keywords

Optics

Rights Statement

Copyright © 2020, author

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