Optical waveguides – Optical fiber waveguide with cladding – Utilizing multiple core or cladding
Patent
1998-09-01
2000-01-11
Ullah, Akm E.
Optical waveguides
Optical fiber waveguide with cladding
Utilizing multiple core or cladding
65425, 65435, 428378, 385145, G02B 602
Patent
active
060144882
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to coated optical fibers whose radiation-curable primary coatings are easy to cleanly strip from the optical fiber.
2. Background Discussion
Optical fibers for light transmission as drawn are exceptionally strong and have very few intrinsic defects. However, even a small surface flaw can render such a fiber brittle and easily broken. Thus, such fibers are generally coated by a primary and optionally a secondary coating for protection as disclosed by U.S. Pat. Nos. 5,352,712, 5,527,835 and 5,538,791 to Shustack, these patents being incorporated herein by reference in their entirety. However, when it is desired to splice optical fibers, these coatings are stripped away to expose the optical fibers so they may be spliced. The removal of these coats, as a preparatory step prior to splicing, entails the risk of scratching or otherwise damaging the optical fiber.
A. Optical Fiber Structure
The primary coating is applied directly to the glass fiber and, when cured, forms a soft, rubbery, compliant material which serves as a buffer to cushion and protect the fiber by relieving the stresses created when the fiber is bent, cabled or spooled. Such stress might otherwise induce microbending of the fibers and cause attenuation of the light traveling through them, resulting in inefficient signal transmission. The secondary coating is applied over the primary coating, and functions as a hard, tough protective outer layer, preventing damage to the glass fiber during processing and use. More than one optical fiber can be combined and embedded in a matrix.
Certain characteristics are desirable for the primary coating layer. For example, it must maintain adequate adhesion to the glass fiber during thermal and hydrolytic aging, yet be strippable therefrom for splicing purposes. The tensile modulus of the primary coating must be low to cushion and protect the fiber by readily relieving the stresses on the fiber which can induce microbending and consequent inefficient signal transmission. This cushioning effect must be maintained through the temperature range to which the fiber may be exposed throughout its lifetime. Thus, it is necessary for the primary coating to have a low glass transition temperature (Tg). This low glass transition temperature will ensure that the coating remains in its rubbery state throughout the possible use temperature range.
The primary coating should also have a relatively high refractive index, i.e., greater than that of the cladding material of the fiber to be coated. This high refractive index allows for a refractive index differential between the glass cladding and the primary coating. This differential allows errant light signals to be refracted away from the glass core.
Another requisite quality of the primary (buffer) coating is resistance to moisture or other solvents, e.g., hydrocarbons. Moisture will rapidly degrade the strength of the coating itself as well as the underlying glass fiber under stress.
Another important property of optical fiber coatings is that, when cured, they have a low content of unbound material. While ultraviolet curable materials are often referred to as 100% solids, they may still contain a significant amount of chemically unbound material after the ultraviolet cure. This unbound material can be extractable with solvent or water, or it can be volatile under certain conditions. The presence of an extractable or volatile component in optical fiber products can cause problems which may be detrimental to the fibers. Such potential problems may manifest themselves throughout the lifetime of the optical fiber.
B. Optical Fiber Stripping Can Cause Problems
Although coated optic fibers are very well made, there is often a need to splice together such fibers. This requires stripping the coatings from the fibers and thus exposes the fibers to risk as discussed above. Residue left of the fibers after stripping contributes to the risk. Thus, in the art of optic fibers, there is a significant nee
REFERENCES:
patent: 4351657 (1982-09-01), Kimura et al.
patent: 4474830 (1984-10-01), Taylor
patent: 4552498 (1985-11-01), Dysarz
patent: 4590493 (1986-05-01), Inoue et al.
patent: 4702554 (1987-10-01), Takahashi et al.
patent: 4839400 (1989-06-01), Sato et al.
patent: 4847132 (1989-07-01), Takao et al.
patent: 4880867 (1989-11-01), Gobel et al.
patent: 4892906 (1990-01-01), Pham et al.
patent: 5000772 (1991-03-01), Petisce
patent: 5043413 (1991-08-01), Tanaka
patent: 5055536 (1991-10-01), Dubois
patent: 5098852 (1992-03-01), Niki et al.
patent: 5128387 (1992-07-01), Shustack
patent: 5128391 (1992-07-01), Shustack
patent: 5146531 (1992-09-01), Shustack
patent: 5197060 (1993-03-01), Yatake
patent: 5238744 (1993-08-01), Williams et al.
patent: 5279862 (1994-01-01), Corcoran et al.
patent: 5279877 (1994-01-01), Uchiyama et al.
patent: 5330786 (1994-07-01), Nonaka et al.
patent: 5400317 (1995-03-01), Strasser et al.
patent: 5427892 (1995-06-01), Strandjord et al.
patent: 5478869 (1995-12-01), Takahashi et al.
patent: 5508981 (1996-04-01), Watanabe et al.
patent: 5510164 (1996-04-01), Best et al.
patent: 5518788 (1996-05-01), Invie
patent: 5533001 (1996-07-01), Watanabe et al.
patent: 5536529 (1996-07-01), Shustack
patent: 5538791 (1996-07-01), Shustack
patent: 5558937 (1996-09-01), Woods et al.
patent: 5703988 (1997-12-01), Oishi et al.
LandOfFree
Coated optical fibers having strippable primary coatings and pro does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coated optical fibers having strippable primary coatings and pro, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coated optical fibers having strippable primary coatings and pro will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1468318