Negative radiation pressure in metamaterials explained by light-driven atomic mass density rarefication waves

TL;DR

This paper demonstrates through simulations that negative radiation pressure in negative-index metamaterials can occur due to light-driven atomic density waves, revealing a new mechanism for negative momentum transfer in these materials.

Contribution

It introduces a detailed simulation-based explanation for negative radiation pressure in NIMs, highlighting the role of atomic density waves and providing guidance for experimental verification.

Findings

Negative radiation pressure depends on NIM structure.

Negative total momentum arises from electromagnetic and material contributions.

Experimental conditions require careful NIM design and joint momentum measurement.

Abstract

The momentum and radiation pressure of light in negative-index metamaterials (NIMs) are commonly expected to reverse their direction from what is observed for normal materials. The negative refraction and inverse Doppler effect of light in NIMs have been experimentally observed, but the equally surprising phenomenon, the negative radiation pressure of light, still lacks experimental verification. We show by simulating the exact position- and time-dependent field-material dynamics in NIMs that the momentum and radiation pressure of light in NIMs can be either positive or negative depending on their subwavelength structure. In NIMs exhibiting negative radiation pressure, the negative total momentum of light is caused by the sum of the positive momentum of the electromagnetic field and the negative momentum of the material. The negative momentum of the material results from the optical force density, which drives atoms backward and reduces the local density of atoms at the site of the light field. In contrast to earlier works, light in NIMs exhibiting negative radiation pressure has both negative total momentum and energy. For the experimental discovery of the negative radiation pressure, one must carefully design the NIM structure and record the joint total pressure of the field and material momentum components.