Optical fibre
First Claim
1. An optical fibre being optically transmissive at a predetermined wavelength of light λ
- and comprising a plurality of coaxial layers each having an optical path length that varies radially, the coaxial layers being arranged to give the fibre a refractive index profile which, in use, causes sufficient Fresnel diffraction of the light such that it is guided in the fibre.
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Accused Products
Abstract
An optical fibre being optically transmissive at a predetermined wavelength of light λ and comprising a plurality of coaxial layers. Each layer having an optical path length that varies radially, the coaxial layers being arranged to give the fibre a refractive index profile which, in use, causes sufficient Fresnel diffraction of the light such that it is guided in the fibre. The refractive index of a cladding region (60) is intermittently suppressed by controlling heating of the preform tube, thus forming a chirped saw-tooth profile (70). The optical fibre may include a lens. In this case, each of the layers has an optical path length that increases gradually outwardly by substantially n×λ/2 (n: integer).
56 Citations
48 Claims
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1. An optical fibre being optically transmissive at a predetermined wavelength of light λ
- and comprising a plurality of coaxial layers each having an optical path length that varies radially, the coaxial layers being arranged to give the fibre a refractive index profile which, in use, causes sufficient Fresnel diffraction of the light such that it is guided in the fibre.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 47)
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31. A method of forming an optical fibre, the method comprising the steps of:
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providing a member having an axis;
depositing a plurality of coaxial layers on the member, each of the layers being composed of a material that is optically transmissive at a predetermined wavelength λ and
being formed such that its optical-path length varies across its thickness, the coaxial layers being arranged to give the fibre a refractive index profile which, in use, causes sufficient Fresnel diffraction of the light such that it is guided in the fibre. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. A method of forming a preform rod suitable for being drawn into an optical fibre, the method comprising the steps of:
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passing a precursor vapour along a preform tube, the precursor vapour including a first precursor for depositing a first material inside the tube, and a second precursor for depositing a second, relatively more volatile, material inside the tube;
heating the preform tube so as to react the precursor and to progressively deposit the first and second materials inside the tube, the second material being distributed within the first material controlling the heating so that a concentration gradient of the second material is controlled by the desorption rate of the second material relative to a desorption rate of the first material. - View Dependent Claims (46, 48)
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Specification