A full vectorial mapping of nanophotonic light fields

TL;DR

This paper presents a robust algorithm that can extract all six electric and magnetic field components from a single near-field measurement without prior sample knowledge, enabling detailed nanoscale optical field mapping.

Contribution

The authors introduce a novel algorithm for full vectorial mapping of nanophotonic light fields from single measurements, eliminating the need for prior sample modeling.

Findings

Successfully unraveled fields of a photonic crystal waveguide

Successfully unraveled fields of a plasmonic nanowire

Enables new studies of complex photonic phenomena at the nanoscale

Abstract

Light is a union of electric and magnetic fields, and nowhere is their complex relationship more evident than in the near fields of nanophotonic structures. There, complicated electric and magnetic fields varying over subwavelength scales are generally present, leading to photonic phenomena such as extraordinary optical momentum, super-chiral fields, and a complex spatial evolution of optical singularities. An understanding of such phenomena requires nanoscale measurements of the complete optical field vector. However, while it was recently demonstrated that near-field scanning optical microscopy is sensitive to the complete electromagnetic field, a separation of the different components required a priori knowledge of the sample. Here we introduce a robust algorithm that can disentangle all six electric and magnetic field components from a single near-field measurement, without any numerical modeling of the structure. As examples, we unravel the fields of two prototypical nanophotonic structures: a photonic crystal waveguide and a plasmonic nanowire. These results pave the way to new studies of complex photonic phenomena at the nanoscale, and for the design of structures that optimize the optical behavior that they exhibit.