SecondHarmonic Generation by Scattering of Surface Plasmons Polaritons by Metallic Nanostructures

1
Second-Harmonic Generation by Scattering of
Surface Plasmons Polaritons by Metallic
Nanostructures Lina Cao1, Nicolae Panoiu2,
Shuang Zhang3, Wenjun Fan3, Kevin J. Malloy3,
Steven R. J. Brueck3, Richard Osgood2        
1Department of Chemistry, Columbia
University        2Department of Applied Physics,
Columbia University 3Center for High
Technology Materials, University of New Mexico
Geometry
Introduction
x3

• How do surface plasmon-polaritons interact with
  surface relief nanostructures
• How do we extract light from nanostructured
  surfaces
• How is SPP energy lost on surfaces
• How do we do frequency up conversion of SPPs

scattered
2-D Gaussian defect
vacuum
Metal Ag
reflected
transmitted
incident
x1
metal
SPP
MotivationPlasmon enhanced fields and
induced optical nonlinearities are important for

• 1. Applications
• Light extraction from nanostructures optical
  nano antennae.
• Facilitate transport of energy of optical near
  field by SPP waveguiding along straight or bent
  line defects.
• Nonlinear optics allows active control of optical
  nanodevices.
• External light-controlled optical switching in
  plasmon-polariton structures.
• Provide a great deal of flexibility in photonic
  integration in all-optical circuits.
• 2. Theory of SHG
• Local enhancement of electromagnetic field at
  FH and SH.
• Analytical description of SHG
• Resonant interaction between plasmons and
  structural nanodefects

Impedance Boundary Condition
First-Harmonic Near Field
Indentations
a 120nm h -80nm l 350nm
PRL 86, 3008 (2001) Proceedings
of SPIE 4810, 71 (2002) S. I. Bozhevolnyi
S. A. Maier
Laser-photodeposited metallic nanostructures R.
Osgood D. J. Ehrlich, Opt. Lett.
At wavelength of minimum light scattering
At wavelength of maximum light scattering

• enhanced field at the defect for both
  wavelengths
• larger field amplitude at the defect ? larger
  amount of scattered light

Bumps

• field at defect is not as large as the field of
  incoming SPP

a 120nm h 80nm l 460nm
2
Second Harmonic Generation by Scattering of
Surface Plasmons Polaritons by Metallic
Nanodefects Lina Cao, Nicolae Panoiu, Shuang
Zhang, Wenjun Fan, Kevin J. Malloy, Steven R. J.
Brueck, Richard Osgood
Results Second Harmonic Fields, Spatial
Distribution Spectra
Angular Distribution of SH Radiation
Shaded domains gt predictions of the model
become less accurate

• electric dipole
• magnetic dipole
• electric quadrupole

• Parameters are chosen so as the strength of the
  three multipoles are comparable to each other
• Different multipoles have the predicted pattern
  of the radiated field
• Orientation of dipole moments are different for
  different defect parameters

More oscillations for indentations than bumps
Conclusions

• First Harmonic
• Different plasmon-defect interaction
  characteristics for indentations and bumps
  multiple resonances for indentations, monotonic
  decrease of scattered light for bumps
• If field enhanced at an indentation due to
  spectral resonance, then more efficient light
  extraction at first harmonic
• 2. Second Harmonic
• At long wavelengths, electric dipole moment
  dominates the radiation, larger defect ? more
  radiation
• At short wavelengths more oscillations in
  spectral response in the case of indentations, as
  compared to the case of bumps
• Slightly larger radiation power for indentations
  than bumps
• Different multipole moments dominate at different
  wavelengths of the incident SPP
• Angular distribution of the emitted SH is
  strongly dependent on the geometry of the
  nanodefect and the wavelength of the incident SPP