Optical response of rectangular array of elliptical plasmonic particles on glass revealed by Mueller matrix ellipsometry and finite element modeling

Abstract

We report here on the optical response of elliptical gold particles arranged in a rectangular lattice on glass and probed at non-normal incidence in reflection using spectroscopic Mueller matrix ellipsometry in the energy range 0.73 − 5.9 eV. The surface plasmon resonances, reshaped near the Rayleigh anomalies, are mapped out by full azimuthal rotation of the sample. The experimental Mueller matrices are discussed and interpretation is supported by finite element modelling of the Mueller-Jones matrix elements, which allows for identification of the dipolar and multipolar responses observed in the experimental spectra. The data show a strong polarization conversion around the surface plasmon resonances as a function of the azimuthal angle of incidence, also reshaped near the Rayleigh lines. An effective strong circular diattenuation is observed from the recorded Mueller matrix. We further argue the importance of Mueller matrix ellipsometry for metrology in the manufacture of metasurfaces, for understanding the effect of the lattice in metasurface design, and finally in validating computational methods.

Systematic analysis of the Rayleigh–Wood anomalies and the symmetry relations of 2D‐periodic nanostructures by imaging spectroscopic ellipsometry

“…A similar truncating effect on the ellipsometric spectra accompanied by distinct spectral "kinks" (first-derivative discontinuities) was previously observed for a gold particle grid on a glass substrate, for which the Rayleigh line overlapped with the localized surface plasmon resonance (LSPR) [30]. Similarly, the peaks in the Ψ spectra observed at about 0.9 eV (purple and pink curves of ROI 6-10, Figure 9a) might be interpreted as the particle resonance of the gold nanoparticles.…”

“…Similarly, the peaks in the Ψ spectra observed at about 0.9 eV (purple and pink curves of ROI 6-10, Figure 9a) might be interpreted as the particle resonance of the gold nanoparticles. However, previous studies reported LSPRs of gold particle arrays at much higher photon energies for similar-sized gold particles although applying glass substrates rather than silicon [14,30]. The resonances were also much more pronounced than the Ψ peaks observed in this work.…”

True Circular Dichroism in Optically Active Achiral Metasurfaces and Its Relation to Chiral Near-Fields

“…The onset of the excitation of diffracted higher orders yields sharp structures in the Mueller matrix elements named Rayleigh anomalies. The signature of the Rayleigh anomalies was also observed (the calculated Rayleigh lines are shown as dotted green lines (Air) and green full lines (glass) in Figure c), but it should be noted that the first anomaly is at 700 nm and it should not affect too much the line shape of the electric and magnetic modes, unlike the quadrupolar modes …”

“…The signature of the Rayleigh anomalies was also observed (the calculated Rayleigh lines are shown as dotted green lines (Air) and green full lines (glass) in Figure 2c), but it should be noted that the first anomaly is at 700 nm and it should not affect too much the line shape of the electric and magnetic modes, unlike the quadrupolar modes. 22 The elements m 14 and m 23 are related to the amplitude and phase of the CDOA, and should arise from the magnetoelectric coupling in optically active achiral metasurfaces illuminated at non-normal incidence. As already described in the literature, 18,25 it can be observed from Figure 3a that the spectral dependence of the element m 14 exhibited a characteristic S-shape crossing zero at the position of the magnetic mode at 815 nm which has the strongest magneto-electric contribution.…”

Roadmap of ellipsometric characterization of plasmonic nanoparticles

“…Recent progress in modeling offers new opportunities to evaluate the influence of the NP size or shape distribution on their optical properties 6,[18][19] . Mueller matrix ellipsometry was used to investigate the shape of NPs organized into array [20][21][22] . As shown by Voloshenko et al 20 , the Mueller matrix symmetry and depolarization factor of this nanostructure are directly related to the NP size and shape.…”