Photonic Band Gap Structures

1
Photonic Band Gap Structures
Mikhail Rybin
Saint Petersburg State University, Ioffe
Physico-Technical Institute
Euler School March-April 2004
2
Overview

• Photonic crystals and photonic bandgap
• Artificial opals
• Photonic bandgap structure of artificial opals
• Transmission experiments
• 4. 3D diffraction of light in opals
  visualization of photonic band gap structure
• 5. Conclusions

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Bragg Diffraction
Wavelength does not correspond to the
period Reflected waves are not in phase. Wave
propagates through.
Wavelength corresponds to the period. Reflected
waves are in phase. Wave does not propagate
inside.
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Bragg Reflection
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Energy gap
Gap in energy spectra of electrons arises in
periodic structure
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PBG formation
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Energy gap in electromagnetic spectrum
Increasing of the dielectric contrast could lead
to the overlapping of energy gaps in any
direction in 3D space.
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Width of complete band gap
Calculation of bandwidth in dependence of
dielectric constants S. John et al. PRE (1998)
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Density of States in fcc structure
There is no states in any direction within
complete photonic band gap S. John et al. PRE
(1998)
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2D PHB Structures
Sharp band waveguide channel in 2D photonic
crystal
Macro-porous silicon material with incorporated
defect line
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Artificial Phonic Structure
E.Yablonovitch et al., PRL (1987, 1991)
Fabrication of artificial fcc material and band
gap structure for such material.
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3D Photonic materials
E. Yablonovitch, PRL(1989)
S.Noda, Nature (1999)
K. Robbie, Nature (1996)
Examples of artificial photonic crystals
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Bragg diffraction through all electromagnetic
region
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Natural Opals
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Artificial Opal
Artificial opal sample (SEM Image) Several
cleaved planes of fcc structure are shown
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Artificial Opal
Images of artificial opal. Left as-growth
surface (111) of the sample (SEM image) Right
surface of the (110)-oriented plane sample (AFM
image)
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Growing process
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Fabrication of artificial opals
There are 3 in-layer position A red B blue
C green Layers could pack in fcc lattice
ABCABC or ACBACB hcp lattice ABABAB
Silica spheres settle in close packed hexagonal
layers
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Inverted Opals
Inversed opals obtain greater dielectric contrast
than opals.
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Diffraction on growth layers
Energy of the gap in transmission and energy of
the maximum in reflection spectra are coincided

• Transmission for different incident angles
• 00
• 200
• 300
• 400
• 540

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Band structure of diamond lattice
Photonic band structure of diamond lattice
(refractive index 3.45) John et. al. PRE (1998)
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Scan planes
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Angular-resolved transmission spectra
Bandgap position for different incident angle
directions
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Structure of Photonic Bandgap
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Experimental Set
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Experiment
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Geometry of 2-spots and 4- spots
Diffraction patterns in two different scattering
geometry (Art image)
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2 spots pattern
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Diffraction Pattern (515 nm)
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Geometry of 2-spots and 4- spots
Diffraction patterns in two different scattering
geometry (Art image)
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2 spots pattern
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Visualization of Photonic Band Structure in opals
?1 515 nm ?2 578 nm ?3 633 nm
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Features in diffraction patterns
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Processing of images
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Conclusions

• Photonic band gap structures are new class of
  material possessed uncial photonic properties.
  Opal-based structures are 3D photonic crystals.
• 2. Photonic band gap structure was obtained for
  artificial opals in the visible range from
  angle-resolved transmission measurements.
• 3. Photonic band gap structure could be
  visualized by diffraction method. Diffraction
  patterns provides information about structure of
  photonic crystal.

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Spontaneous Emission Control
Emission is forbidden if energy of photonic
bandgap and width of electrons energy gap are
coincided.