Optical waveguides – With optical coupler – Particular coupling structure
Reexamination Certificate
2002-06-04
2004-05-25
Healy, Brian (Department: 2874)
Optical waveguides
With optical coupler
Particular coupling structure
C385S042000, C385S096000, C065S406000, C065S408000, C065S411000
Reexamination Certificate
active
06741774
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fabrication of fiber optic devices, and more particularly to a fabrication method that produces fiber optic devices having improved intrinsic resistance to external environmental conditions.
BACKGROUND OF THE INVENTION
The widespread and global deployment of fiber optic networks and systems mandates that fiber optic devices and components operate reliably over long periods of time. This mandate imposes stringent performance requirements on various fiber optic devices and components that are used in such networks and systems. In this respect, since fiber optic devices and components are expected to operate reliably for decades or more, prior to qualification for use, such components are typically subjected to an array of mechanical and environmental tests that are designed to measure their long term reliability.
Guarantees of long term performance become especially crucial in application where the cost of failure is very high (e.g., submarine applications.) One of these tests is a damp/heat soak test, where a fiber optic device or component is exposed to elevated temperature and humidity conditions (typically 85° C. and 85% relative humidity) for an extended period of time. Fiber optic couplers exposed to such conditions may exhibit a gradual drift in insertion loss. Eventually, this drift will cause a coupler to fail to meet its assigned performance specifications.
It is believed that the primary cause for the above-identified drift is water vapor or some component, constituent or by-product of water vapor diffusing into the exposed core glass of the coupler and changing the coupler's index of refraction.
In an attempt to prevent migration of moisture into the coupling region, it has been known to provide improved packaging for optic couplers, with the goal of eliminating exposure to external environment. For example, prior art approaches have included packaging fiber optic couplers and other fiber optic components inside a metal tubing and sealing the ends of the tubing with a polymeric material, such as a silicon-based material or epoxy. These types of packaging have not proved successful in preventing the aforementioned problem.
Other prior art approaches have focused on reducing the introduction of water vapor during the manufacturing process. These attempts include the use of heat sources, such as a solid state heaters alone, that introduce less hydrogen/water during fabrication of a coupler, than is introduced using an “open flame” heat source. However, these attempts have also failed. Such approaches are deficient because it has been discovered that the introduction of water and water related species during fabrication is not a major cause of long-term drift of optical properties under damp heat accelerated aging conditions. See Maack et. al, Confirmation of a Water Diffusion Model for Splitter Coupling Ration Drift Using Long Term Reliability Data. See also, Cryan et al., Long Term Splitting Ration Drifts in Singlemode Fused Fiber Optic Splitters, Proc. Nat. Fiber Opt. Eng. Conf. Jun. 18-22, 1995.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a method of forming an optical device having a region treated by deuterium, comprising the steps of maintaining first and second optic fibers proximate to one another along a segment, and fusing together the segment to form a coupling region in the presence of a flame produced by combustion of deuterium gas.
In another aspect, the invention provides a method where the first and second optical fibers have different propagation constants.
In another aspect, the invention provides a method where a diameter of said first optic fiber is modified to change the propagation constant.
In another aspect, the invention provides a method where the diameter of one of the optic fibers is modified by heating the optic fiber while stretching the first optical fiber to reduce its diameter in a portion of the optic fiber.
In another aspect, the invention provides a coupler comprising at least two optic fibers having respective longitudinal segments, where the longitudinal segments are fused together in the presence of a flame produced by combustion of deuterium gas.
In another aspect, the invention provides a method where another chemical or compound is added to the deuterium fuel.
In another aspect, the invention provides a method where oxygen is added to the deuterium fuel.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and advantages of the invention will be realized and attained by the structure and steps particularly pointed out in the written description, the claims and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part hereof, and wherein:
FIG. 1
is a schematic diagram of a preferred embodiment of an optical fiber before stretching.
FIG. 2
is a schematic diagram of a preferred embodiment of an apparatus used to stretch an optical fiber.
FIG. 3
is an enlarged schematic diagram of a preferred embodiment of an optical fiber after a pre-taper operation has been performed.
FIG. 4
is an enlarged isometric view of a preferred embodiment of an apparatus and a coupler.
FIG. 5
is a graph showing change is splitting loss over time.
FIG. 6
is a graph showing median time to failure for various optical devices.
FIG. 7
is a chart showing probability distributions of rates of change of splitting loss at 85° C./85%RH.
FIG. 8
is a table including data from TTF experiments.
REFERENCES:
patent: 4138194 (1979-02-01), Beasley et al.
patent: 4515612 (1985-05-01), Burrus, Jr. et al.
patent: 4632513 (1986-12-01), Stowe et al.
patent: 4689065 (1987-08-01), Krause
patent: 4798436 (1989-01-01), Mortimore
patent: 4798438 (1989-01-01), Moore et al.
patent: 5011252 (1991-04-01), Thorncraft et al.
patent: 5104433 (1992-04-01), Chapin et al.
patent: 5204927 (1993-04-01), Chin et al.
patent: 5205851 (1993-04-01), Suganuma et al.
patent: 5216731 (1993-06-01), Murphy et al.
patent: 5217517 (1993-06-01), Rossberg
patent: 5222167 (1993-06-01), Jean et al.
patent: 5223014 (1993-06-01), Yamauchi et al.
patent: 5298291 (1994-03-01), Klinger et al.
patent: 5302316 (1994-04-01), Hashimoto et al.
patent: 5355426 (1994-10-01), Daniel et al.
patent: 5405657 (1995-04-01), Bastian et al.
patent: 5409777 (1995-04-01), Kennedy et al.
patent: 5730922 (1998-03-01), Babb et al.
patent: 5744514 (1998-04-01), Shustack
patent: 5787218 (1998-07-01), Ohtaka et al.
patent: 5796893 (1998-08-01), Huang et al.
patent: 5822482 (1998-10-01), Atkeisson et al.
patent: 5891930 (1999-04-01), Lapin et al.
patent: 5985374 (1999-11-01), Grabbe et al.
patent: 6004477 (1999-12-01), Nakagawa et al.
patent: 6018965 (2000-02-01), Bloom
patent: 6052503 (2000-04-01), Schouten et al.
patent: 6063888 (2000-05-01), Yamaguchi et al.
patent: 6084999 (2000-07-01), Shen et al.
patent: 6112001 (2000-08-01), Kishida et al.
patent: 6136880 (2000-10-01), Snowwhite et al.
patent: 6148129 (2000-11-01), Pan et al.
patent: 6180741 (2001-01-01), Yamaguchi et al.
patent: 6220059 (2001-04-01), Klein et al.
patent: 6222973 (2001-04-01), Starodubov
patent: 6258404 (2001-07-01), Morgand et al.
patent: 6269680 (2001-08-01), Prieve et al.
patent: 6272266 (2001-08-01), Peck, Jr.
patent: 6282343 (2001-08-01), Kim et al.
patent: 6298189 (2001-10-01), Szum et al.
patent: 6301412 (2001-10-01), Mori et al.
patent: 6310998 (2001-10-01), Starodubov
patent: 2001/0020049 (2001-09-01), Takase et al.
Maack et al., “Confirmation of a Water Diffusion Model for Splitter Coupling Ration Drift Using Long Term Reliability Data, ” AUGAT Aster, Inc., 86 S. Street, Hopkinton, MA (pp. 559-566).
Cryan et al., “Long Term Splitting Ration Drifts in Singlemode Fused Fiber
Hoffman, III Arthur J.
Tallent Jack R.
Gould Fiber Optics, Inc.
Healy Brian
Shaw Pittman LLP
Wood Kevin S.
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