Optical waveguides – Accessories – Splice box and surplus fiber storage/trays/organizers/ carriers
Reexamination Certificate
2001-04-05
2003-07-08
Kim, Robert H. (Department: 2882)
Optical waveguides
Accessories
Splice box and surplus fiber storage/trays/organizers/ carriers
C385S037000, C385S134000, C385S136000, C385S137000, C385S059000
Reexamination Certificate
active
06591054
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an article used as a filament storage device to facilitate filament positioning during modification of a filament. More particularly the invention provides a filament organizer including a detachable positioner for conveniently handling an accessory to be attached to a filament, especially an optical fiber to produce a functional optical device. Such a device includes a temperature compensated optical fiber Bragg grating that may be precisely tuned to a prescribed wavelength using a tuning apparatus according to the present invention.
BACKGROUND OF THE INVENTION
Technological advancements, particularly in telecommunications, have caused a migration from systems and devices based upon electronics to those that integrate electronics with optics. These systems and related devices are known collectively as optoelectronics. The movement of signals using photons instead of electrons provides advantages of speed, information-carrying capability, immunity from interference, lower cost, and higher reliability.
Growth of optoelectronic systems occurs as phone companies increasingly promote the use of fiber-optic cable and related devices for developing ever-expanding telecommunications networks. Success in telecommunications markets has produced a demand for innovations in fiber-optic technology. Increasing demand for products typically translates into a need to accelerate the output rate and assembly of products and systems desired by consumers. Acceleration of output rates depends upon efficiency in manufacturing operations, usually through process automation.
Methods used currently for assembly and testing of optoelectronic systems and devices are largely manual and time consuming. This applies particularly to processes for introducing special features such as periodic refractive index gratings into optical fibers. Formation of a refractive index grating, or Bragg grating, into an optical fiber requires a number of steps for manually handling lengths of optical fiber during a series of manufacturing operations.
A optical fiber Bragg grating provides a periodic variation of refractive index within a length of an optical fiber. The grating may be formed or written during exposure of a photosensitive optical fiber to an appropriate pattern of ultraviolet radiation. Applications for Bragg gratings exist in telecommunications systems to control the wavelength of laser light, to introduce dispersion compensation, for example. The characteristics of Bragg gratings change with changes of strain and temperature. A change in temperature will change the wavelength of light transmitted via a Bragg grating, with undesirable consequences. One solution to this problem is the use of a temperature compensating structure attached to the portion of an optical fiber containing the Bragg grating. This is usually accomplished by clamping a Bragg grating containing optical fiber, under tension, into a mechanical structure combining a low expansion material with a high expansion material. This method of passive temperature compensation is well known as a means for improving wavelength stability of optical fiber Bragg gratings. U.S. Pat. No. 5,042,898 discloses an apparatus for temperature compensation of a fiber Bragg grating comprising two juxtaposed compensating members with the required differences in thermal expansion. The apparatus applies either tensile or compressive stress to the grating. Other references addressing temperature compensation of optical fiber Bragg gratings, using fiber length variation, include United States Patents U.S. Pat. No. 5,991,483, U.S. Pat. No. 6,101,301 and WIPO publication WO 98/59267. Japanese publication JP 9211348 describes the use of a piezoelectric transducer to modulate the strain in a fiber in response to electrical signals. Such devices are effective but costly.
Temperature compensated optical fiber Bragg grating packages, as previously discussed, are typically large, exhibiting variation of reflection wavelength from one package to another. In some cases, the design of temperature compensating structures is complex requiring multiple points of connection to form a package having a negative coefficient of thermal expansion. Some temperature compensated packages include fine adjustment of the grating wavelength but this may involve complicated procedures such as the extension or compression of the total package as described in WO 98/59267.
Regardless of the availability of solutions for compensating the temperature drift of optical fiber Bragg gratings, little has been revealed for automating processes either for forming Bragg gratings or attaching structures or accessories to optical fibers to perform a desired function such as temperature compensation. With increasing demand for optoelectronic systems there is a need to improve optical fiber handling to achieve more cost effective production of large quantities of optical fiber devices.
SUMMARY OF THE INVENTION
The present invention satisfies the need for effective and compact handling of filamentary materials during manufacturing operations including process steps that include attaching accessories to a filament and producing structural and related changes in the filament. When applied to optical fibers, an article, also described herein as a filament organizer, provides compact containment of an optical fiber during the writing of an optical fiber Bragg grating and further processing to provide a temperature compensated optical fiber Bragg grating package. Preferably the filament organizer includes a detachable accessory positioner. The filament organizer allows relatively precise positioning of at least a section of optical fiber to facilitate attachment of accessories, such as thermal compensators, held temporarily in an accessory cradle of an accessory positioner.
An accessory positioner, adapted for variable positioning in a filament organizer, conveniently allows placement of an accessory in the accessory cradle when there is a spaced relationship between the accessory positioner and a filament, preferably an optical fiber. Using suitable means to move the accessory positioner in the filament organizer, an accessory may be moved towards a filament with precise alignment of the two before joining them together. Means to facilitate movement of an accessory positioner between positions include sliding motion on e.g. racks, or tracks or movement based upon the use of bearings, bars, hinges, cams and the like.
A filament organizer according to the present invention may be used to assemble filamentary devices, particularly devices including optical fibers. An example of such use involves either changing the inherent characteristics of an optical fiber or incorporating an optical fiber into a functional assembly. The inherent characteristics of an optical fiber change with adjustment of its refractive index properties, as in the formation of a variety of fiber Bragg gratings. Incorporation of an optical fiber into a functional assembly provides useful devices such as temperature compensated fiber Bragg gratings. Refractive index changes and functional assembly production, according to the present invention, use a filament organizer during the formation of a temperature compensated optical fiber Bragg grating. Thereafter an optical fiber Bragg grating may be precisely tuned using an accessory positioner with a tuning jig according to the present invention.
More particularly, the present invention provides a filament organizer for attaching an accessory to a section of filament. The filament organizer comprises a frame including a plurality of guides. Also, the filament organizer includes an accessory positioner adapted for sliding engagement with the frame between a first position and a second position. The accessory positioner includes a first spool and a second spool having a filament extended between them to pass around the guides. This locates the section of filament for attachment of an accessory. An accessory cradle, included with the accessory positioner, rec
Afflerbaugh Martin G.
Cronk Bryon J.
Howard Patrick Charles
Wiegand Gordon
3M Innovative Properties Company
Ball Alan
Kim Robert H.
Wang George
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