Nanoparticle Spectroscopy: Birefringence in Two-Dimensional Arrays of L-Shaped Silver Nanoparticles

Abstract

We present theoretical models and experiments demonstrating nanoparticle optical birefringence. The experiments use polarization optical methods to describe the birefringence properties of two-dimensional arrays of L-shaped silver nanoparticles. These particles have two major resonances with perpendicular polarization directions. The beam depolarization at incident angles intermediate to the resonance polarization directions is explained with a model based on a finite-difference time-domain (FDTD) calculation for both arrays and single particles. The maximum relative phase retardation is observed between the two overlapping dipole resonance wavelengths, and experimentally it is about 30°. While the FDTD models predict a larger effect of up to 105°, this might be due to the statistical variation of nanoparticle shapes in the experimental arrays. The arrays were fabricated by electron beam lithography, and the size of particles was ∼145 and ∼155 nm in nominal total edge length, 63 nm arm width, and 30 nm he...