Coherently Coupled Optical Waveguide

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Coherently Coupled Optical Waveguide

• ? ? ? ? ? ?
• ????? ? ? ? ?

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Outline

• Introduction
• Paper Review
• Principle of Operation
• Experiences and Results
• Summery
• References

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Introduction

• Motivation
• Optical bending waveguide are used to change the
  direction of light propagation in many integrated
  optical devices such as MZ and directional
  couplers. In order to reduce the device area and
  increase the packing density, we must to find
  bend structures with large bend angles and low
  loss.
• Structure Curved optical waveguide Conventional
  bend waveguide Etched-wall bend waveguide
  Coupler bend waveguide Prism waveguide.
• Principle of coupler bend waveguide
• Coupled-bend transmission can be an oscillatory
  function of the interconnection length L due to
  interference between the guided and radiation
  modes.
• Material
• Ti Ni Zn and Ni

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• Introduction
• Paper Review
• Principle of Operation
• Experiences and Results
• Summery
• References

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Conventional Bend Waveguide
P0 output power Pi input power ?0 radiation
and absorb parameter Lo distance of optical beam
propagating in waveguide T power combine
parameter(
)
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Etched-wall Bend Waveguide
Wave front in the part is speeded up to make
bending easier and reduce the power loss.
Advantage power loss is lower than convention
bend waveguide. Disadvantage As ? larger than
20, power loss will be higher and make this
bending waveguide not to have the ability of
light propagation.
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Coupler Bend Waveguide
d
Advantage power loss is lower with suitable
coherent length.
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• Introduction
• Paper Review
• Principle of Operation
• Experiences and Results
• Summery
• References

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Principle of Coherent Coupler I
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1
2
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Principle of Coherent Coupler II
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Principle of Coherent Coupler III
Guided mode
Radiation mode
The equation shows that the coupled-bend
transmission can be an oscillatory function of
the interconnection length L due to interference
between the guided and radiation modes.
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Principle of Coherent Coupler V
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Principle of Coherent Coupler VI
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• Introduction
• Paper Review
• Principle of Operation
• Experiences and Results
• Summery
• References

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Coherently Coupler Bend
SECTION LENGTH, L( ?m )
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Coherently Coupler Bend
N 2
NUMBER OF SECTIONS ( N )
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Coherently Coupler Bend
(a)standard structure
(b)new structure
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Transmitted Power with Total Bending Angle
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Transmitted Power with Launching Wavelength
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Summery

• The transmission function of the coupler bend
  waveguide depends on the interference of guided
  mode and radiation mode in the interconnection
  length L.
• We study the principle of coupler bend waveguide
  which is better than conventional bend and
  etched-wall bend waveguide in being a suitable
  bending structure with large bend angles and low
  loss.
• Other new structures include prism and new
  structure couple bend waveguide.

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References

• L. M. Johnson and F. J. Leonberger, Low-loss
  LiNbO3 waveguide bends with coherent coupling,
  Optics Letters, Vol. 8, No. 2, Feb. 1983.
• L. M. Johnson and D. Yap, Theoretical analysis
  of coherently coupled optical waveguide bends,
  Applied Optics, Vol. 23, No.17, 1 Sep.1984.
• ???, An Investigation of integrated optical
  waveguide bends,
• ???, Coherent-coupling-based wide-angle bending
  optical waveguide design and fabrication,