Inverse Opals

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Inverse Opals
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Inverse Opal Band Gap
good agreement between theory (black)
experiment (red/blue)
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Photonic Crystals Based on Macroporous Silicon
Holes are focused onto the pore tips Because of
the SCR
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2-Dimensional Photonic Crystal
High aspect ratio gt 100
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Reflection of a 2-D Photonic crystal
----------- Noncoupling bands
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Noncoupling bands
Z
K
Ez is symmetric with respect to a plane
containing the z-axis and K
Such a plane wave can only couple to photonic
crystal modes if they have same symmetry
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Band-gap Tuning and Switching
r/a ratio 0.47 16 band-gap
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Optical Switch

• Change of symmetry
• Mechanically stretching not appropriate
• Change of lattice constant
• Thermal expansion not appropriate
• Dielectric contrast
• Filling liquid crystal easy
• a1.58um 70nm shift (4.4um6um range)
• Not suitable for high speed switching
  (microseconds)
• Vary the dielectric constant of the Si itself
• By the creation of carriers by illuminations of
  sample
• High speed switching (picoseconds)

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Expected shift of the Bandedge
29nm bandedge shift at 1910nm
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Few pore rows
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Defects in 2-D Photonic Crystals
Pore next to defect are larger then other pores
Defect leas to the formation of new photonic
state within the Photonic Bandgap
Z-direction has no photonic crystal crystal based
confinement
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Defects in 2-D Photonic Crystals
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3-D Photonic Crystals
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3-D Photonic Crystals
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Reduction of the Group Velocity
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Defects in 3-D Photonic Crystals