Microbend optical fiber tapped delay line
First Claim
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1. A tapped optical fiber delay line, comprising:
- a length of optical fiber positioned on a form having at least one raised portion, said fiber having first and second segments, each of said first segments passing over a raised portion on the form so as to create a bend of radius sufficiently small to cause a portion of a light signal traveling in said first segments to be directed out of said fiber at said first segments, and any bend radius in said second segments being sufficiently large to prohibit a portion of a light signal traveling in said second segments from being directed out of said fiber at said second segments; and
means for detecting light directed out of said fiber at said first segments.
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Abstract
A fiber optic tapped delay line is disclosed in which a number of bends in a single optical fiber are formed to obtain taps of an optical signal traveling in that fiber at each bend location. Light removed at the bends is directed to a focusing lens, which focuses the light onto a photodetector acting as a summing device to produce a frequency-filtered output of the light signal traveling in the fiber. The device'"'"'s response as a transversal filter is enhanced by weighting the taps either by use of a cylindrical lens, or by selectively masking a portion of light emitted by selected individual taps.
54 Citations
27 Claims
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1. A tapped optical fiber delay line, comprising:
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a length of optical fiber positioned on a form having at least one raised portion, said fiber having first and second segments, each of said first segments passing over a raised portion on the form so as to create a bend of radius sufficiently small to cause a portion of a light signal traveling in said first segments to be directed out of said fiber at said first segments, and any bend radius in said second segments being sufficiently large to prohibit a portion of a light signal traveling in said second segments from being directed out of said fiber at said second segments; and means for detecting light directed out of said fiber at said first segments. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A tapped optical fiber delay line, comprising:
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a form having at least one raised portion; a length of optical fiber positioned on the form such than at least one segment of the fiber passes over the raised portion, so that a bend is formed in the fiber by force produced exclusively between the fiber and the raised portion, said bend being of sufficiently small radius to permit sampling, at said bend, of a light signal traveling in the fiber; and means for detecting light sampled at the bend in the fiber. - View Dependent Claims (15, 16, 20)
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17. A tapped optical fiber delay line, comprising:
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a length of optical fiber wound around a form to provide plural loops, said form exerting a force on said fiber exclusively from the interior of said loops at selected plural locations along said fiber to form plural bends in said fiber at said selected plural locations, said bends of sufficiently small radius to cause light traveling within said fiber to be directed out of said fiber at said bends; and means for detecting at least a portion of the light emitted from said fiber at said bends. - View Dependent Claims (18)
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19. A tapped optical fiber delay line, comprising:
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an optical fiber for receiving a light signal; and means for applying a force exclusively to one side of said optical fiber at plural locations along said fiber to form plural bends in said fiber at said plural locations, respectively, to cause light to be emitted from said fiber at said plural locations, said means for applying a force applying said force only to the side of the fiber opposite the side from which light is emitted.
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21. A method of tapping an optical fiber delay line comprising the steps of:
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providing a first form having a surface whose diameter is sufficiently large to prevent severe bending and associated loss of light from an optical fiber positioned thereon; positioning a raised member on at least a portion of the surface of the first form; wrapping a segment of an optical fiber around the form in a configuration such that at least a portion of said segment passes over the raised member so as to form a bend in the fiber of a radius sufficiently small to cause a portion of a light signal traveling in the fiber to be directed out of said fiber at the bend; and positioning, adjacent the bend, a means of detecting the light emitted from the fiber at the bend. - View Dependent Claims (22, 23)
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24. A method of filtering an optical signal, comprising:
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projecting a light signal into an optical fiber wound around a form, one portion of said form being configured so as to cause a bend in an adjacent portion of each revolution of said fiber at which point light is emitted; summing the light emitted from said fiber; and reducing the intensity of a portion of the light emitted from selected bends of said fiber, which light is being summed, said reduction causing a resulting frequency passband shape to be varied. - View Dependent Claims (25)
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26. A method of tapping light from an optical fiber, comprising:
projecting a light signal into an optical fiber; and
applying a force exclusively to one side of said optical fiber at plural locations along said fiber to create plural bends in said fiber at said plural locations, respectively, to cause light to be emitted from said fiber at said plural locations.- View Dependent Claims (27)
Specification