Post on 19-Dec-2015
Magnificent Optical Properties of Noble Metal Spheres, Rods and Holes
Peter Andersen and Kathy RowlenDepartment of Chemistry and Biochemistry
University of Colorado, Boulder
Funded by the National Science Foundation
1970’s surface enhanced Raman scattering
1980’s 106 enhancement of Raman scattering
1980’s second harmonic generation
1997 1014 enhancement of Raman scattering
2000 106 enhancement of fluorescence in nanorods
2001 surface plasmon optics
Surface Plasmons: coherent oscillations of electron density at metal/dielectric interface
Enhanced Optical Processes from Nanometric Noble Metal Particles
Enhanced Optical Transmission
Ebbesen et al. “Extraordinary Optical TransmissionThrough Sub-Wavelength Hole Arrays”
Nature, 1998, 391, 667-669
Saloman et al. Phys. Rev. Lett. 2001, 86(6), 1110
• 200 nm Ag film v.d. onto quartz• focused ion beam lithography• 150 nm holes• 600 nm to micron spacing
Ghaemi et al. Phys. Rev. B 1998, 58(11), 6779
Thio et al., J. Opt. Soc. Am. B., 1999, 16(10), 1743
Measured Near-Field Distribution
Closest to simulated c (previous), hole d = 500 nm
Ebbesen et al. Nature 1998, 391,667
• 200 nm thick Ag• 150 nm holes• 900 nm spacing
• Transmission efficiency =fraction of light transmitted/fraction of surface area holes = 2.
• More than twice the lightthat impinges on the holes is transmitted through the film!
Ebbesen et al. Nature 1998, 391,667
• Hole spacing determines peak position
•Peak position independent of hole d
• Independent of metal (Ag, Cr, Au)
• Must be metal (Ge doesn’t work)
T scales with d2, independent of
versus (d/ )4 for Bethe sub- aperture
=500 nm
Not cavity resonance since peak position (in spectrum)does not significantly depend on hole dimensions
Not waveguiding because film thickness too small (200 nm)
Surface plasmon tunneling?
Surface plasmon scattering?
Enhancement / Transport Mechanism?
•For a surface that can support a surface plasmon, the wave vector, ksp is:
•The difference between the in-plane wave vector of light,
ki, and the surface plasmon wave vector, ksp, can be
compensated for by diffraction on periodic surface structure:
2/1
2
sm
smi
spk
max 2 2( , )
m s
m soi j ai j
min 2 2( , ) s
oi j ai j
Grupp et al., Appl. Phys. Lett. 2000, 77(11), 1569
Ag
Ag/Ni
Ni
Grupp et al., Appl. Phys. Lett. 2000, 77(11), 1569
Transmission relatively independent of wall metal
Sonnichsen et al., Appl. Phys. Lett. 2000, 76(2), 140
Further evidence for surface plasmon involvement
Sonnichsen et al., Appl. Phys. Lett. 2000, 76(2), 140
Saloman et al. Phys. Rev. Lett. 2001, 86(6), 1110
Left: Calculated near-fieldtransmission intensity[(c) = 300 d, 900 nm a, 800 nm ]
Calculated intensityenhancement nearhole edge ~ 500x
15 nm above 100 nm above
Thio et al., Physica B, 2000, 279, 90
Grupp et al. Adv. Matr. 1999, 11(10), 860
Thio et al., Physica B, 2000, 279, 90
Surface Plasmon Activated Devices
Grupp et al. Adv. Matr. 1999, 11(10), 860
Transmission through single holewith array of dimples
Single hole in smooth surface
Thio, Lezec, Ebbesen Physica B, 2000, 279, 90
For coherent 670 nm lightT is 60x greater than typicalNSOM tapered fiber with200 nm aperture
Applications, Applications, Applications!
Reflection mode?
SERS at edges?
Field in channel?
Surface Plasmon Optics:
• use SP’s for manipulation of optical fields
• SP lenses, mirrors and flashlights (e.g., Smolynaninov et al. Phys. Rev. B. 1997, 56(3) 1601-1611.)
Optical Enhancement via Surface Plasmon Coupling
h Field enhanced detection region
Light harvesting indentations
Surface plasmon mirrorTransmission channel
Surface plasmon lense
Si substrate Spin coat substrate with PMMA resist
Expose to electron beam
Develop in MIBK/IPA
Metalize by vapor deposition
Electron-Beam Nanolithography (Peter Andersen)
Reflection Grating Behavior
First Attempt: Top-View AFM
AFM Micrograph of Second Attempt!
target ao 450 nm measured ao 450 nm
Grating Constant (ao)
Lens Pinhole Au MirrorNd:YAG Laser
= / 2sin
Photolithography (Michele Jacobson)
To be continued…..