Defect-induced nonlinearity in 2D nanoparticles

TL;DR

This paper investigates how defects in 2D dielectric nanoparticles influence their optical nonlinearity, revealing defect-specific signatures that could enable ultra-high-density optical data storage and novel QR-code applications.

Contribution

It introduces a model showing defect-induced nonlinearity in 2D nanoparticles and highlights the potential for defect engineering in optical data storage.

Findings

Defects at particle edges significantly enhance even-order nonlinearity.

Distinct defect states produce unique nonlinear signatures.

Potential for 1 bit per atom data storage using defect signatures.

Abstract

Optical nonlinearity depends on symmetry and symmetries vanish in the presence of defects. Vaccancy defects in centrosymmetric crystals and thin films are a well-known source of even-order optical nonlinearity, e.g. causing second harmonic generation. The emerging ability to manipulate defects in two-dimensional materials and nanoparticles provides an opportunity for engineering of optical nonlinearity. Here, we demonstrate the effect of defects on the nonlinear optical response of two-dimensional dielectric nanoparticles. Using a toy model, where bound optical electrons of linear atoms are coupled by nonlinear Coulomb interactions, we model defect-induced nonlinearity. We find that defects at particle edges contribute strongly to even-order optical nonlinearity and that unique nonlinear signatures of different defect states could provide the smallest conceivable QR-codes and extremely high density optical data storage, in principle approaching 1 bit per atom.