US 2002/0071881 A1Published application

Apparatus and method for manufacturing fiber gratings

OwnerVictor Il?apos;ich Kopp, Azriel Zelig Genack +1inventors

InventorsVictor Il?apos;ich Kopp, Azriel Zelig Genack, Richard Mead

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Abstract

In accordance with the apparatus and method of the present invention an optical fiber is heated and twisted to produce a periodic modulation of the dielectric constant along the fiber axis. This structure can be used in any application that utilizes Bragg grating optical fibers. A preform is drawn through a heater and the resulting optical fiber is twisted about its longitudinal axis. The refractive index modulation in the optical fiber arises from birefringence induced by stress in the optical fiber that is twisted after being subjected to an uneven heat distribution during the drawing process. The refractive index is modulated by drawing and twisting the optical fiber from a specially constructed preform which is non-cylindrically symmetrical.

Claims40

Dependent claims

An apparatus for utilizing a preform, having a first end and a second end, to manufacture an optical fiber having a modulation of the dielectric constant along its longitudinal axis, the apparatus comprising:

feeding means for:
securing the first end of the preform, and
feeding the preform at a predefined feeding speed;
heating means, arranged sequentially to said feeding means, for receiving the preform and for heating the preform to a predefined process temperature at a predefined heating location, said process temperature being sufficient to cause the preform to be susceptible to drawing and twisting;
and
drawing means, arranged sequentially to said heating means, for:
engaging the second end of the preform;
drawing the preform from said feeding means through said heating means at a predefined drawing speed to produce the optical fiber drawn from the preform at said predetermined location within said heating means, said drawing speed being one greater than or equal to said feeding speed;
and
twisting the optical fiber around the longitudinal axis at a predefined twisting speed, at said predetermined location, to produce a twisted optical fiber having a periodic modulation of the dielectric constant along the longitudinal axis.

7 more elements

A method for fabricating an optical fiber having a modulation of the dielectric constant along its longitudinal axis from a preform having a first end and a second end, the method comprising the steps of:

(a) securing the first end of the preform;
(b) feeding the preform at a predefined feeding speed through a heating unit;
(c) heating the preform to a predefined process temperature at a predetermined location in said heating unit, said process temperature being sufficient to cause the preform to be susceptible to drawing and twisting;
and
(d) engaging the second end of the preform;
(e) drawing the preform through said heating unit at a predefined drawing speed to produce the optical fiber drawn from the preform at said predetermined location within said heating unit, said drawing speed being greater than or equal to said feeding speed;
and
(f) twisting the optical fiber around the longitudinal axis at a predefined twisting speed, at said predetermined location, to produce a twisted optical fiber having a periodic modulation of the dielectric constant along the longitudinal axis.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/925,590Filed 9 Aug 2001
Priority: 9 Aug 2000
Published: 13 Jun 2002
Term ends: Not estimatedThe source records don’t support an estimate.

Classification20 codes

C03B 37/032
Drawing means, e.g. drawing drums ; Traction or tensioning devices: for glass optical fibres
C03B 37/0253
From reheated softened tubes, rods, fibres or filaments , e.g. drawing fibres from preforms: controlling or regulating
C03B 37/027
From reheated softened tubes, rods, fibres or filaments , e.g. drawing fibres from preforms: fibres composed of different sorts of glass, e.g.…
C03B 37/02718
Fibres composed of different sorts of glass, e.g. glass optical fibres: thermal treatment of the fibre during the drawing process, e.g. cooling