Far-field optical microscope with nanometer-scale resolution based on in-plane surface plasmon imaging

TL;DR

This paper introduces a far-field optical microscope utilizing in-plane surface plasmon imaging to achieve nanometer-scale resolution, overcoming previous limitations and demonstrating resolutions better than 50 nm at 502 nm wavelength.

Contribution

The paper presents a novel surface plasmon-based microscopy technique that surpasses prior theoretical limits by addressing propagation constraints, achieving sub-50 nm resolution in practical experiments.

Findings

Resolution better than 50 nm demonstrated

Overcoming propagation limitations extends magnification

Supports high-resolution imaging with surface plasmons

Abstract

A new far-field optical microscopy technique capable of reaching nanometer-scale resolution has been developed recently using the in-plane image magnification by surface plasmon polaritons. This microscopy is based on the optical properties of a metal-dielectric interface that may, in principle, provide extremely large values of the effective refractive index n up to 100-1000 as seen by the surface plasmons. Thus, the theoretical diffraction limit on resolution becomes lambda/2n, and falls into the nanometer-scale range. The experimental realization of the microscope has demonstrated the optical resolution better than 50 nm for 502 nm illumination wavelength. However, the theory of such surface plasmon-based far-field microscope presented so far gives an oversimplified picture of its operation. For example, the imaginary part of the metal dielectric constant severely limits the surface-plasmon propagation and the shortest attainable wavelength in most cases, which in turn limits the microscope magnification. Here I describe how this limitation has been overcome in the experiment, and analyze the practical limits on the surface plasmon microscope resolution. In addition, I present more experimental results, which strongly support the conclusion of extremely high spatial resolution of the surface plasmon microscope.