Optical Fibers - Khulna University...(1) Gerd Keiser, Optical Fiber Communications, 2nd Edition...
Transcript of Optical Fibers - Khulna University...(1) Gerd Keiser, Optical Fiber Communications, 2nd Edition...
Opto-electronic Devices and Optical
Communication
Optical Fibers:
Structures, Waveguiding, and Fabrication
Lecture 2 Presented By~
Dr. Md. Shamim Ahsan
Professor
ECE Discipline, Khulna University
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Outline
Wave Propagation Analysis
Fiber Geometry
Waveguide Equations & Boundary Conditions
Modal Equation & Modes in Step-index Fiber
V Parameter and Number of Modes
Power Flow in Step-index Fiber
Propagation Modes in Step-index and Graded-index Fibers
Optical Fiber Basics
Polarization
Nature of Light
Fiber & Cable Structure, and Fiber Fabrication
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The Nature of Light
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The Nature of Light
Figure: Representation of spherical and plane wave fronts and their associated rays.
ure
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The Nature of Light
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Optical Waveguide Concept
Figure: Physical model showing the ray
propagation and the corresponding
transverse electric (TE) field patterns of
three lower order models (m = 1, 2, 3) in
the planar dielectric guide.
(c) m = 3
(d)
E
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Skew Rays
The ray that is transmitted through the optical fiber without
passing through the fiber axis is called skew ray.
Skew rays follows the helical path through the optical fiber
as shown in the following figure.
Figure: The helical path taken by a skew ray
in an optical fiber.(a) skew ray path down the
fiber; (b) cross-sectional view of the fiber.
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Wave Propagation For Bulk Material
Similarly, by taking the curl of we obtain:
22
0 0 2r r
EH
t
Wave Propagation Equation
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For the inside region, the
solution of the guided
modes must remain finite
as r 0, whereas on the
outside the solutions must
decay to zero as r .
when, r
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Solution of Some Problems
1
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Solution of Some Problems
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Solution of Problem Regarding V Parameter and # of Modes
(2)
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Solution of Problem Regarding V Parameter and # of Modes
(3)
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Solution of Problem Regarding V Parameter and # of Modes
(4)
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Solution of Problem Regarding Cutoff Wavelength
(5)
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Power Flow in Step Index Fiber
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Solution of Problem Regarding Power Flow in Step Index Fiber
(6)
ure
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Graded Index Fibers
Figure: Possible fiber refractive index profiles for different
values of .
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Solution of Problem Regarding Graded Index Fiber
(7)
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Solution of Problem Regarding # of Modes in Graded Index Fiber
(8)
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Video: Fiber Fabrication
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Generator
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References: (1) Gerd Keiser, Optical Fiber Communications, 2nd Edition (1991), Chapter 2.
(2) Dennis Roddy and John Coolen, Electronic Communications, Fourth Edition (2000),
Chapter 20.
(3) John M. Senior, Optical Fiber Communications, 3rd Edition (2009), Chapter 2.
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