Browsing by Author "Hattori, Haroldo Takashi"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Fiber Designs with Significantly Reduced Nonlinearity For Very Long Distance Transmission
    Hattori, Haroldo Takashi; Safaai-Jazi, Ahmad (Optical Society of America, 1998-09-01)
    A class of low-nonlinearity dispersion-shifted fibers based on depressed-core multistep index profiles is investigated. A systematic approach for designing these fibers in which a reference W-index profile is used to initiate the design is presented. Transmission properties, including effective area, mode-field diameter, dispersion, dispersion slope, and cutoff wavelength, are evaluated for several design examples. The effects of varying fiber dimensions and indices on effective area and mode-field diameter are assessed. It is shown that there is a trade-off between these two properties and, generally, larger effective areas are associated with larger mode-field diameters. Dispersion-shifted single-mode fiber designs with effective areas of from 78 to 210 mu m(2) and the corresponding mode-field diameter of from 8.94 to 14.94 mu m, dispersion less than 0.07 ps/nm km, and dispersion slope of approximately 0.05 ps/nm(2) km are presented. (C) 1998 Optical Society of America.
  • Thumbnail Image
    Low Nonlinearity Optical Fibers for Broadband and Long-Distance Communications
    Hattori, Haroldo Takashi (Virginia Tech, 1998-02-11)
    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 μm² to 210 μm² and the corresponding mode-field-diameter of 8.94 μm to 14.94 μm, 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 μm < λ < 1.58 μm, the effective-area is 75 μm² to 100 μm², while the dispersion remains below 0.7 ps/nm.km.