Engineering optical forces through Maxwell stress tensor inverse design

TL;DR

This paper introduces a versatile inverse design framework using Maxwell stress tensor formalism to optimize optical systems for manipulating particles of any size or shape, enabling complex control such as trapping and acceleration.

Contribution

The work presents a novel inverse design method that accounts for arbitrary particle geometries and sizes, extending beyond traditional point dipole approximations.

Findings

Successfully designed systems for attracting, repelling, and trapping particles.

Applicable to free-space and particle-metalens systems.

Demonstrated control over particle dynamics through inverse design.

Abstract

Precise spatial manipulation of particles via optical forces is essential in many research areas, ranging from biophysics to atomic physics. Central to this effort is the challenge of designing optical systems that are optimized for specific applications. Traditional design methods often rely on trial-and-error methods, or on models that approximate the particle as a point dipole, which only works for particles much smaller than the wavelength of the electromagnetic field. In this work, we present a general inverse design framework based on the Maxwell stress tensor formalism capable of simultaneously designing all components of the system, while being applicable to particles of arbitrary sizes and shapes. Notably, we show that with small modifications to the baseline formulation, it is possible to engineer systems capable of attracting, repelling, accelerating, oscillating, and trapping particles. We demonstrate our method using various case studies where we simultaneously design the particle and its environment, with particular focus on free-space particles and particle-metalens systems.