Chapter 4: Comprehensive Focal Field Engineering With Vectorial Optical Fields

Abstract

The propagation and focusing properties of spatially variant polarization remain of continued research interest owing to their promising applications in physics, chemistry and biological sciences. The main challenges to these applications are the optimization of focus shape, size and the control of polarization distribution within the focal volume. In this chapter, systematic approaches that are suitable for comprehensive three-dimensional focal field engineering are reviewed. Threedimensional flattop focusing with extended depth of focus and optical bubble is illustrated through the use of generalized cylindrical vector beam illumination and diffractive optical element (DOE). Combining the radiation pattern from an electric dipole and the Richards-Wolf vectorial diffraction method, the required input field at the pupil plane of a high numerical aperture objective lens for generating arbitrary threedimensional polarization at the focal point with an optimal spot size can be found analytically by solving an inverse problem. Diffraction-limited spherical spots with three-dimensionally controllable polarization can be realized through applying this radiation reversal approach to 4-π microscopy. Several other exotic optical focal field distributions, such as high purity longitudinally polarized optical needle field with extended depth of focus, extremely long optical tube and uniform optical chain, are demonstrated through the reversal of the radiation pattern from linear electric and magnetic dipole arrays. Vectorial Optical Fields Downloaded from www.worldscientific.com by UNIVERSITY OF BIRMINGHAM LIBRARY -INFORMATION SERVICES on 03/21/15. For personal use only. 126 W. Chen and Q. Zhan