Complex far fields and optical singularities due to propagation beyond tight focusing: combined effects of wavefront curvature and aperture diffraction

Abstract

All optical systems, which involve the collimation of a reflected, transmitted or scattered wave subsequent to tight focusing, are subject to two kinds of deviations. One is the wavefront curvature due to inaccurate focal placement of the interface or scatterer particle under consideration, and the other is the diffraction caused by the finite lens aperture. In the present paper we explore these phenomena in detail by considering a rigorous simulated model and an appropriate experimental setup. We hence demonstrate the complicated intensity profiles and optical singularity characteristics of the observed far field. Then we describe ways to minimize these deviations in a general experiment. But more importantly, our analysis proves that these deviations by themselves are significant optical phenomena of fundamental interest. The observed complex field profiles have similarities to standard diffraction-limited tight focal fields, though our field detection is different from the standard schemes. This indicates the relevance of these complex fields to a larger class of systems involving wavefront curvature and aperture diffraction. The detailed analysis and results of the present paper already serve as core explorations of these optical phenomena; and we also suggest future research directions where these system aspects can be purposefully created and explored further.

17 pages, 17 figures

References in corpus (12)

• Spin-to-orbital angular momentum conversion in focusing, scattering, and imaging systems
• Optical nanoprobing via spin-orbit interaction of light
• Photothermal Heterodyne Imaging of Individual Metallic Nanoparticles: Theory versus Experiments
• Geometric phases in 2D and 3D polarized fields: geometrical, dynamical, and topological aspects
• On the experimental investigation of the electric and magnetic response of a single nano-structure
• A Simple Analytical Model of the Angular Momentum Transformation in Strongly Focused Light Beams
• Identifying the tilt angle and correcting the orbital angular momentum spectrum dispersion of misaligned light beam
• Identifying orbital angular momentum of vectorial vortices with Pancharatnam phase and Stokes parameters
• Vectorial vortex generation and phase singularities upon Brewster reflection
• Optical Singularity Dynamics and Spin-Orbit Interaction due to a Normal-Incident Optical Beam Reflected at a Plane Dielectric Interface
• Generic Optical Singularities in Brewster-reflected Post-paraxial Beam-fields
• Generalized Matrix Transformation Formalism for Reflection and Transmission of Complex Optical Waves at a Plane Dielectric Interface