Superlens induced loss-insensitive optical force

TL;DR

This paper demonstrates that a superlens can induce a maximum optical force on a small particle at a specific distance, and surprisingly, this force remains stable or can even increase with loss, challenging the belief that loss degrades superlens performance.

Contribution

It reveals that superlens-induced optical forces are loss-insensitive and can be enhanced by loss, providing new insights into superlens applications in optical manipulation.

Findings

Maximum optical force occurs at a critical distance from the superlens.

The maximum force remains constant despite changes in material loss within a range.

Increasing loss can amplify the optical force on the particle.

Abstract

A slab with relative permittivity $\epsilon = - 1 + i\delta$ and permeability $\mu = - 1 + i\delta $ has a critical distance away from the slab where a small particle will either be cloaked or imaged depending on whether it is located inside or outside that critical distance. We find that the optical force acting on a small cylinder under plane wave illumination reaches a maximum value at this critical distance. Contrary to the usual observation that superlens systems should be highly loss-sensitive, this maximum optical force remains a constant when loss is changed within a certain range. For a fixed particle-slab distance, increasing loss can even amplify the optical force acting on the small cylinder, contrary to the usual belief that loss compromises the response of supenlens.