Nanointerferometric Amplitude and Phase Reconstruction of Tightly Focused Vector Beams

TL;DR

This paper introduces a simple measurement and reconstruction method using a nanoparticle probe to accurately map the amplitude and phase of tightly focused vector beams with sub-wavelength resolution, enhancing nano-optics and microscopy.

Contribution

It presents a straightforward scheme for full-field reconstruction of vector beams using scattering signals from a single nanoparticle, avoiding complex near-field techniques.

Findings

Reconstructed amplitudes and phases of focal fields with sub-wavelength resolution.

Achieved accurate field mapping from a single scan measurement.

Eliminated the need for polarization analysis of scattered light.

Abstract

Highly confined vectorial electromagnetic field distributions represent an excellent tool for detailed studies in nano-optics and high resolution microscopy, such as nonlinear microscopy, advanced fluorescence imaging or nanoplasmonics. Such field distributions can be generated, for instance, by tight focussing of polarized light beams. To guarantee high quality and resolution in the investigation of objects with sub-wavelength dimensions, the precise knowledge of the spatial distribution of the exciting vectorial field is of utmost importance. Full-field reconstruction methods presented so far involved, for instance, complex near-field techniques. Here, we demonstrate a simple and straight-forward to implement measurement scheme and reconstruction algorithm based on the scattering signal of a single spherical nanoparticle as a field-probe. We are able to reconstruct the amplitudes of the individual focal field components as well as their relative phase distributions with sub-wavelength resolution from a single scan measurement without the need for polarization analysis of the scattered light. This scheme can help to improve modern microscopy and nanoscopy techniques.