The Chimaerical Quest for the Optical Plasmonic Superlens

TL;DR

This paper critically examines claims about a silver film superlens, clarifying misconceptions about its imaging capabilities and explaining the physical mechanisms behind surface plasmon resonance and evanescent field interactions.

Contribution

It provides a physical explanation of surface plasmon excitation and refutes the claim that the superlens can image real subwavelength objects, highlighting experimental misinterpretations.

Findings

The superlens does not image real subwavelength objects.

Evanescent fields are crucial for surface plasmon excitation.

Surface plasmons undergo subwavelength conversion and reduction.

Abstract

This commentary aims to expose the fallacy of claiming that a plasmonic silver film superlens is capable to image real subwavelength objects. This lens was proposed by the Berkeley's group who, in their misleading experiment, inappropriately regarded subwavelength apertures as the objects to be imaged whereas the main function of these apertures was to transform free space laser light into an evanescent field necessary for exciting the surface plasmon resonance phenomenon in silver. In addition, the apertures also determined the constrained effective area on the silver film where the phenomenon could occur. We provide a fresh insightful physical explanation of how this phenomenon is excited and what it entails. We emphasize the phenomenon's important effect of subwavelength conversion (reduction) of the generated surface plasmons and their associated bound enhanced evanescent fields.