Optics on a Nanoscale Using Polaritonic and Plasmonic Materials

1
Optics on a Nanoscale Using Polaritonic and
Plasmonic Materials (NSF NIRT 0709323) Andrey
Chabanov1, Federico Capasso2, Vinothan
Manoharan2, Michael Spencer3, Gennady Shvets4,
Christian Zorman5 1University of Texas-San
Antonio, 2Harvard University, 3Cornell
University, 4University of Texas-Austin, 5Case
Western Reserve University
Motivation and Goals Coupling Optical Energy to
Nanoscale
Subsurface imaging through a SiC-superlens
microstructure
Light diffraction prevents confinement of light
in regions smaller than half a laser wavelength
thus impeding the development of future
nanophotonic devices and limiting future
nanoimaging applications. Surface polaritons, on
the other hand, can have wavelengths that are
orders of magnitude shorter than in vacuum. Thus
plasmonic/ polaritonic components may enable us
to achieve unprecedented focusing of optical
energy that can address the needs of
nanophotonics, nanomanufacturing, NEMS, nanoscale
thermal source development, and nanofluidics. The
Key Challenges in coupling optical energy to
nanoscale are addressed by the NIRT (i)
Creating nanoscale polariton-based building
blocks of metamaterials/ metafluids with
controlled optical properties (ii)
Accomplishing strongly subwavelength, nanoscale
resolution by designing a mid-infrared
polariton-based superlens integrated with a
scattering NSOM (iii) Demonstration of
extraordinary optical energy focusing on a
nanoscale through the excitation and guiding of
surface polaritons. The plasmonic/ polaritonic
components aimed by the NIRT are to lead to in
vivo imaging of nanoscale biological objects and
revolutionize label-free detection of biological
and chemical substances.

• Resolution of ?/20 for 2-D objects (holes)
  
• Increased range of frequencies for imaging ?
  amplitude or phase
• Higher resolution with phase imaging ? less
  sensitive to topography

Seeing through water in vivo imaging of small
biological objects

• Bonding of SiC membranes to PDMS holder
  demonstrated
• Fluid delivery system (microfluidic channels
  connect to the nanofluidic sub-surface channel)
  developed and tested
• Presently working on the inscription of small
  objects (holes, metal discs, etc.) at the bottom
  of the nanofluidic channel

Artificial Plasmonic Molecules-based metafluids
Liquid metamaterials, or metafluids, are based on
clusters of metallic nanoparticles, or Artificial
Plasmonic Molecules (APMs), which exhibit strong
electric and magnetic responses. Colloidal
solutions of plasmonic nanoclusters can act as an
optical medium with very large, small, or even
negative effective permittivity and substantial
effective magnetic permeability in the visible
and near-infrared spectral bands. The properties
of the metafluids can be controlled by an
external signal.

• Silica cores are synthesized and functionalized
  with a silane linker
• Gold nanoparticles are self-assembled onto the
  surface and gold shells with controllable shell
  thickness are created by electroless deposition
• Gold nanoshells are assembled into trimers
  using capillary-force clustering or DNA-mediated
  adhesion
• Single nanoshell absorption spectra of
  particles are measured in air on a glass substrate

Perfect impedance matched negative index material
absorber
continuous silver wires control eeff
cut silver wires control m eff
20 nm
50 nm
80 nm
80 nm
320 nm
250 nm
This structure is subwavelength (period ?/5 )
and operates in e µ -1 regime

• Peak absorption varies between 100 and 75 for
  the 90-deg full-angle spread
• Absorption peak is spectrally narrow (10) and
  widely tunable (1300nm lt ? lt 1600nm)
• Using high melting temperature metals (e.g.
  tungsten) shifts the wavelength to ? 2.4 µm and
  enables thermovoltaic applications
• Using SiC ? shifts resonances to ? 11 µm ?
  night-vision applications