Polarimetric techniques for determining morphology and optical features of high refractive index dielectric nanoparticle size

Fernando Moreno,Francisco González,José M Saiz,Juan M Sanz,Rodrigo Alcaraz De La Osa,Ángela I Barreda

doi:10.1117/12.2229488

Fernando Moreno, Francisco González + Show 4 more

Open Access

https://doi.org/10.1117/12.2229488

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Publication Date: Mar 14, 2016
Citations: 1	License type: other-oa

Affiliation: Universidad de Cantabria

Abstract

The spectral evolution of the degree of linear polarization (P L ) at a scattering angle of 90° is studied numerically for high refractive index (HRI) dielectric spherical nanoparticles. The behaviour of P L (90°) is analyzed as a function of the refractive index of the surrounding medium and the particle radius. We focus on the spectral region where both electric and magnetic resonances of order not higher than two are located for various semiconductor materials with low absorption. The spectral behavior of P L (90°) has only a small, linear dependence on nanoparticle size R. This weak dependence makes it experimentally feasible to perform real-time retrievals of both the refractive index of the external medium and the NP size R. From an industrial point of view, pure materials are nonrealistic, since they can only be provided under certain conditions. For this reason, we also study the effect of contaminants on the resonances of silicon NPs by considering the spectral evolution of P L (90°).

Highlights

Nanotechnology has revolutionized science with important theoretical and practical developments
Values of all resonances evolve with mmed, so that an estimate of mmed can be obtained through the values of PL(90o), for those wavelengths where resonances occur, λres
We show the sensitivity of linear polarization degree SP(90o) to NP purity where the percent Si ranges from 100% to 98.98% for a R = 200 nm spherical NP embedded in vacuum

Summary

INTRODUCTION

Nanotechnology has revolutionized science with important theoretical and practical developments. Instead of electronic plasma oscillations, certain distributions of displacement currents leading to whispering gallery-like modes are responsible for resonances in dielectric NPs4 These are located in well-defined spectral ranges, depend on the NPs size and shape, and can be of either electric or magnetic nature, the particle magnetic permeability μ has a value of 15. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 03/17/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx and, in particular, for those with high values of electric permittivity, the characteristics of PL(90o) allow one to distinguish between their intrinsic electric or magnetic responses[9, 15] Another important factor that influences the behavior of the resonances is the purity of the NP material.

THEORETICAL METHODS

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CONCLUSION