Optical waveguides – Optical fiber waveguide with cladding – Utilizing multiple core or cladding
Reexamination Certificate
1999-07-27
2001-10-16
Palmer, Phan T. H. (Department: 2874)
Optical waveguides
Optical fiber waveguide with cladding
Utilizing multiple core or cladding
C385S122000
Reexamination Certificate
active
06304704
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to optical fiber and methods of manufacturing optical fiber. More particularly, the invention relates to optical fiber coatings and methods of coating optical fibers.
2. Description of the Related Art
High performance communications systems, i.e., those systems having gigabit transmission speeds, are being made possible by improving the bandwidth of optical fiber. However, achieving those desired transmission speeds in multimode fiber has been hindered by problems such as dispersion. Because multimode optical fibers are capable of propagating more than one mode of optical energy, an inherent problem with dispersion exists. Such dispersion, more specifically known as modal dispersion, is the broadening or spreading of an optical energy output pulse caused by delays resulting from various modes traveling through the optical transmission medium at different speeds. Such dispersion can be managed by mode mixing or mode coupling. i.e., the mixing or scrambling of the various modes in such a way that effectively reduces the difference in travel times of the various modes. The reduction in dispersion improves the bandwidth of the multimode optical fiber.
It has been recognized that certain microbending of multimode fiber often causes advantageous mode coupling or mode mixing. That is, the introduction of perturbations in the multimode cladding modes enhances mode coupling. Conventional approaches to inducing microbending has varied from externally inducing bends in the outer regions of the fiber (see, e.g., U.S. Pat. No. 4,038,062, which is co-owned with this application) to internally applying refractive index perturbations in the optical fiber preforms that subsequently are drawn into optical fibers (see, e.g., U.S. Pat. Nos. 5,867,616 and 5,613.028). Many conventional methods for inducing microbending techniques have had difficulty in controllably introducing perturbations and reliably reproducing the desired microbends. Furthermore. many conventional microbending techniques are undesirable from the standpoint of manufacturing cost and efficiency.
Accordingly, there remains a need for controllably inducing microbends in optical energy transmission medium such as optical fibers to enhance mode coupling therein.
SUMMARY OF THE INVENTION
The invention is embodied in a system for transmitting optical energy including a source of optical energy, an optical energy transmission medium such as an optical fiber and a receiver of optical energy. The optical energy transmission medium includes bubbles disposed therein for inducing microbending of the optical energy transmission medium, thus promoting advantageous mode coupling, which improves bandwidth potential by reducing dispersion. The bubbles are disposed, e.g., in one or more buffer region layers formed around the coating of an optical energy transmission medium such as an optical fiber. Alternatively, the bubbles are disposed at the interface formed between the buffer and coating regions of the optical energy transmission medium.
An alternative embodiment of the invention includes a method of making an optical energy transmission medium. The method includes providing an optical energy transmission medium with a core, a cladding region around the core and a coating region around the cladding region, and forming one or more buffer region layers around the coating region in such a way that a plurality of bubbles are maintained within one or more of the buffer region layers and/or at the interface between the buffer region and the coating region. The quantity and size of the bubbles disposed in the optical energy transmission medium are controlled, e.g., by the amount of moisture present in the coating region.
Yet another alternative embodiment of the invention includes a medium for transmitting optical energy within an optical communications system. The medium is, e.g., an optical fiber having a glass core and cladding region surrounded by one or more coating region layers made of ultraviolet (UV)-cured acrylate or other suitable material. The optical fiber is surrounded by one or more buffer region layers having a plurality of bubbles disposed within one or more of the buffer region layers and/or along the interface between the buffer region and the coating region. The bubbles form perturbations in the optical fiber in a manner that advantageously enhances mode coupling. The buffer region layers are made of a suitable material such as, e.g., poly(vinylidene fluoride) (PVDF) or other fluoropolymer, nylon, polyolefin, poly(vinyl chloride) (PVC), or polyester.
Still another alternative embodiment of the invention includes a method of transmitting optical energy in an optical communications system. The system includes an optical energy source. optical energy receiver and an optical energy transmission such as an optical fiber coupled therebetween. The transmission method includes providing an optical energy transmission medium that has bubbles disposed therein for inducing microbending of the optical energy transmission medium and enhancing mode coupling therein. The transmission method also includes transmitting optical energy from the source to the receiver through the optical energy transmission medium. The enhanced mode coupling resulting from microbending caused by the bubbles improves the bandwidth transmission characteristics of the transmission system.
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Kalish David
Neveux, Jr. Paul Emilien
Ritger Albert John
Taylor Carl Raymond
Turnipseed John Michael
Harman John M.
Lucent Technologies - Inc.
Palmer Phan T. H.
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