Posted August 26, 2016 by fismots in Research Results

Validity of classical coupled oscillators model for elucidating surface plasmon effects on optical scattering by silver nanocylinders

twocylindersfromside_baru
twocylindersfromside_baru

A study is conducted to examine the possibility of explaining the spectral features TE
wave scattered by a single and two silver nanocylinders on the basis of a classical coupled
oscillators model. The two oscillators representing the nanocylinder are specified by
separate eigen frequencies and damping factors with a coupling constant between them,
while the influences of the incoming wave on the oscillators are represented by separate
driving forces. The validity of the model is examined by the quality of fitting and its
resulted spectral profiles with those calculated from the exact formulation of Mie theory.
In the case of a single nanocylinder, excellent fit of R2 ≥ 0.99 is found for cylinder radius
ranging from 20 nm to 40 nm. The best fitted parameters show that the so-called dark
oscillator has a narrow spectral profile representing the contribution of surface plasmon
resonance while the other so-called bright oscillator has a broad spectral profile that
can be associated with the contribution of the slowly-varying scattered background. For
scattering by two nanocylinders with separation , excellent fits are also obtained for
wide range of  from 15 nm to 100 nm by introducing Lorentzian-like dispersive coupling
between the dark oscillators for both incident light normal and along the axis connecting
the cylinders. This study has thus demonstrated the roles of surface plasmon and the
plasmonic interactions for the appearance of Fano-like asymmetric cross-section profile.

Principal researcher: Alexander A. Iskandar
Funding:  ProgramRiset dan Inovasi 2015 from Institut Teknologi Bandung (Contract No. 238a/I1.C01/PL/2015)

Journal of Nonlinear Optical Physics & Materials
Vol. 25, No. 1 (2016) 1650006
DOI: 10.1142/S0218863516500065