Electroabsorption in Metallic Nanoparticles within Transparent Dielectric Media

Mrinal Thakur,Justin Van Cleave

doi:10.3390/app10144904

Abstract

Electroabsorption in metallic nanoparticles within transparent dielectric media has been measured. In particular, gold nanoparticles in glass and subnanometer-size metallic domains in iodine doped nonconjugated conductive polymer have been studied. Measurements have been made for applied ac fields at 4 kHz, at a wavelength close to the onset of the surface plasmon resonance. The measured electroabsorption (imaginary part of χ(3) or Kerr coefficient) has a quadratic dependence on electric field. Its magnitudes were compared for different sizes of the metallic nanoparticles down to the subnanometer-size particles in iodine-doped nonconjugated conductive polymer. As in the case of quadratic electro-optic effect reported earlier, electroabsorption has approximately a 1/d3 dependence, d being the diameter of nanoparticle. This is consistent with existing theories on confined metallic systems.

Highlights

Nonlinear optics in metal nanoparticles within transparent dielectric media has been studied extensively [1,2,3,4,5,6,7,8,9,10,11,12,13]
The focus of the present report is on measurement of electroabsorption in gold nanoparticles of various sizes to further elucidate the mechanisms of nonlinear optics in these important systems
Electroabsorption/the imaginary part of Kerr coefficient (K) increases rapidly as particle size is decreased

Summary

Introduction

Nonlinear optics in metal nanoparticles within transparent dielectric media has been studied extensively [1,2,3,4,5,6,7,8,9,10,11,12,13]. We have reported quadratic electro-optic effect in metallic nanoparticles within dielectric media [6]. We have compared quadratic electro-optic effect in metal (gold) nanoparticles in glass with that of subnanometer-size metallic domains within doped nonconjugated conductive polymers [5]. The focus of the present report is on measurement of electroabsorption in gold nanoparticles of various sizes to further elucidate the mechanisms of nonlinear optics in these important systems. Quadratic electro-optic measurements were successfully carried out and a clear correlation between the real part of Kerr coefficient (K) and diameter of metal nanoparticles was established down to the subnanometer domain [6]. We discuss results of electroabsorption measurements in gold nanoparticles as well as in specific doped nonconjugated conductive polymers which have subnanometer-size metallic domains (quantum dots)

Experimental

Results and Discussion

The imaginary

Electroabsorption

Conclusions