Hollow core planar waveguides and multilayers

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Hollow core planar waveguides and multilayers

• Prof. M. Skorobogatiy, review for the course
• Introduction to Photonic Crystals
• École Polytechnique de Montréal
• Montréal, QC, Canada

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Hollow core planar waveguide, scaling relations
T
T
ql/D
R3
R
D
R2
R4
D2/l
I1
REFLECTOR
T
T
TIR silica fiber D10mm l1.55mm,
loss0.2dB/km T10-6-10-5
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Metallic reflectors
q
Metallic Reflector Omnidirectional reflection,
high material loss in the IR

• Simplest mirrors present thin layers of metals
  such as aluminum deposited on glass substrates.
  Choice of metals will determine reflection
  characteristics of a mirror.
• Aluminum is the cheapest and least expensive
  material with a coefficient of reflection of
  88-92 in the visible.
• More expensive is silver with reflectivity of
  95-99 even in the IR, while less than 90 in
  the blue and UV.
• Most expensive is gold with an excellent
  reflectivity of 98-99 in the IR, while poor
  reflectivity below 550 nm.

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Losses of hollow metallic waveguides
D100mm l1-10mm T10-2 Losses1-10 dB/m
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Dielectric reflectors
Reflectance
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Contraste dindice saugmente
s-pol
p-pol
SiO2-air 0.04 AsSe-air 0.22
Conventional Dielectric Mirrors Very low material
absorption loss, strong dependence of reflection
characteristics on the light polarization
Contraste dindice saugmente
q1
tan-1(nh/nl)
90o
0

• Dielectric mirrors are characterised by very low
  absorption losses, but their reflection
  characteristics are strongly dependent of the
  angle of radiation incidence and polarization.
  For the s-polarized light reflectivity increases
  monotonically with an increase of an angle of
  incidence. However, for a p-polarised light
  reflectivity goes through zero at a so called
  Brewster angle.

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Losses of hollow dielectric waveguides
T
D100mm l1-10mm nc1 nr1.5 LossesTE0.04-4
dB/cm
ql/D
R
D
I1
REFLECTOR
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ARROW waveguides
l1.55mm LossesTE0.2 dB/cm
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ARROW multilayer waveguides
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Planar antiresonant reflecting optical (ARROW)
waveguides, SiN/SiO2 (2.1/1.46)
dc3.7mm
12mm
Capillary
1 layer
Sensor applications - putting the light where the
analyte (gas) is
2 layers
3 layers
D. Yin et al. 14 June 2004 / Vol. 12, No. 12 /
OPTICS EXPRESS 2710
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Omnidirectional reflectorsORhigh index contrast
multilayers
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Multilayer dielectric reflectors
Omnidirectional Dielectric Mirrors Reflection for
all angles of incidence and polarizations
normal q0o
Ep
Es
q
q90o

• Omnidirectional reflection - for any incoming
  polarization and any angle of incidence radiation
  is completely reflected in a certain frequency
  band.

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Omnidirectional dielectric reflectors
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Omnidirectional dielectric reflectors
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Omnidirectional dielectric reflectors
When cladding index nc is increased beyond a
critical value, omnidirectional reflectivity is
lost.
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Omnidirectional reflectorsSURPRIZE !!!low index
contrast multilayers
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All-polymer multilayers
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Giant birefringence polymer multilayers
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Giant birefringence polymer guides