Condensed-Matter Physics & Materials Science Seminar

Surface plasmon polaritons are the key element for extending the power
of photonics to the nanoscale. They confine the light energy to a
nanolayer on the surface of conducing media and strongly enhance the
electromagnetic fields, busting the nonlinear optical effects and
offering novel subwavelength passive and active elements for information
and sensor technologies.
In this report we will show our approach to the local generation,
nanoscale focusing, and guiding of plasmons using different kinds of
nanostructures on the surface of noble metal films machined by the
focused ion beam. We study evanescent fields on the surface using
near-field scanning optical microscopy and retrieve both real and
imaginary parts of the surface plasmon wave vector from the plasmon
interference patterns. The interference of plasmon waves from
neighboring nanosources and holographic interference of plasmons with
the illuminating beam from a tunable laser allow to build the plasmon
dispersion curve. We calculate the dispersion in different
approximations and extract the dielectric constant of silver films by
fitting the experimental data. Both the plasma frequency and the
electron scattering rate characterizing the dielectric constant in the
Drude approach turn out to be different from traditionally cited
text-book values. We refer this difference to the structural sensitivity
of Drude parameters.
Our approach to plasmonic hybrids and active all-photonic plasmon
devices will be also discussed.