Title page for ETD etd-11398-12380

Type of Document Dissertation
Author Hattori, Haroldo Takashi
Author's Email Address hattori@ee.vt.edu
URN etd-11398-12380
Title Low Nonlinearity Optical Fibers for Broadband and Long-Distance Communications
Degree PhD
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Safaai-Jazi, Ahmad Committee Chair
Besieris, Ioannis M. Committee Member
Johnson, Lee W. Committee Member
Poon, Ting-Chung Committee Member
Scales, Wayne A. Committee Member
  • Optical fiber design
  • fiber optics
  • communications
Date of Defense 1998-02-11
Availability unrestricted
A class of low nonlinearity dispersion-shifted and dispersion-flattened fibers for

broadband and long haul applications is presented. The refractive index profiles of these

fibers assume a depressed-core multi-clad geometry in order to achieve effective-areas

much larger than those in conventional optical fibers.

A systematic approach for designing large effective-area dispersion-shifted fibers, using a

reference W-index profile to initiate the design, is presented. Transmission properties,

including effective-area, mode-field-diameter, dispersion, dispersion slope, cutoff

wavelength, and bending, microbending and splice losses are evaluated for several design

examples. To ascertain that the proposed fibers can be practically fabricated, the effects

of varying fiber dimensions and indices on effective-area, mode-field-diameter and

dispersion are assessed.

It is shown that there is a trade-off between effective-area and mode-field-diameter and,

generally, larger effective-areas are associated with larger mode-field-diameters. In other

words, less signal distortion due to fiber nonlinearity (larger effective-area) is associated

with higher power loss due to bending of fiber (larger mode-field-diameter). Thus, a large

effective-area and low bending loss are conflicting requirements. A parameter Q is

defined as a performance indicator, considering effective-area and mode-field-diameter.

Dispersion-shifted single-mode fiber designs with effective-areas of 78 mm

2 to 210 mm2 and the corresponding mode-field-diameter of 8.94 mm to 14.94 mm,

dispersion less than 0.07 ps/nm.km, and dispersion slope of about 0.05 ps/ nm2.km are

presented. Numerical simulations for propagation of pulses in few designed fibers are

performed.Designs of large effective-area dispersion-flattened fibers are also presented,

for the first time we believe. These fibers provide large effective-area and low dispersion

over an extended range of wavelengths. For our design, over the wavelength range of 1.48 mm <

l < 1.58 mm, the effective-area is 75 mm2 to 100 mm2, while the dispersion remains

below 0.7 ps/nm.km.

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