Abstracts - Dipartimento di Elettronica Applicata

Meta 2010 & FEM 2010 – Rome, 13-15 December 2010
Role of Resonances of Digital Plasmonic
Gratings in Absorption Profile Remodulation
Pierfrancesco Zilio (1,2) , Davide Sammito (2,3) and Filippo Romanato (1,2,3)
(1) University of Padova, Department of Physics
Padova, Italy – E-mail: pierfrancesco.zilio@pd.infn.it
(2) LaNN - Laboratory of Nanofabriaction of Nanodevices- viale Stati Uniti 4.
35200 Padova, Italy.
(2) IOM-CNR- S.S. 14 km 163.5- Basovizza Trieste
Padova, Italy – E-mail: filippo.romanato@venetonanotech.it
This work investigates the potentialities of 1D subwavelength digital metallic
gratings to modulate the EM field absorption profile in the silicon substrate
underneath. Two well known optical properties of such structures are
particularly attractive for this purpose: Surface Plasmon Polaritons (SPP) and
the Extraordinary Optical Transmission (EOT) [1].
We focused on the optical response of the system to a normally impinging
1000nm-monochromatic TM-polarized wave, varying systematically both
period (d) and thickness (h) of the grating. The ratio between slit width and
period is kept constant to 0.1. The full EM fields distribution has been
computed using COMSOL Multiphysics software which implements a finite
elements analysis. For each configuration (h,d) we calculated transmittance
and absorptance within different depths in silicon. We also computed the
effective absorption profile of light as a function of depth in silicon. The same
results have been computed using also a semi-analytical model based on the
decomposition of the fields in Bloch-Floquet modes in air and silicon and in
waveguide modes within the slits [2].
a) b)
Figure 1 – a) Transmittance map as a function of period and thickness of the grating. Solid
lines represent predictions of the analytic model. b) Grating configurations showing
respectively Extraordinary Optical Transmission (left) and Surface Plasmon Polaritons (right).
References
[1] F.J. Garcia-Vidal, L.M. Martin-Moreno, T.W. Ebbesen, L. Kuipers, “Light passing
through subwavelength apertures”, Rev. Mod. Phys. , 82, pp. 729-787 (2010).
[2] P. Zilio, D. Sammito, G. Zacco and F. Romanato, “Absorption profile modulation by
means of 1D digital plasmonic gratings”, Optics Express, 18, pp. 19558-19565 (2010).
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