US 6,856,742 B2Granted

Optical fibres with special bending and dispersion properties

AssigneeCrystal Fibre A/S

InventorsJes Broeng, Stig Eigil Barkou Libori, Anders Overgaard Bjarklev

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Abstract

A microstructured optical fiber having a specially designed cladding to provide single mode waveguidance and low sensitivity to bending losses. In one aspect the optical fiber has an inner and an outer cladding each comprising elongated features. The inner cladding features have normalized dimensions in the range from 0.35 to 0.50 and the outer cladding features have normalized dimensions in the range from 0.5 to 0.9, where the normalization factor is a typical feature spacing. The fiber is further characterized by a feature spacing of the inner cladding larger than 2.0 micron. In a second aspect, the fiber has a special non-circular and non-equilateral-polygonial outer cross-sectional shape to mechanically ensure bending in predetermined directions that are favourable with respect to low bending losses. The present invention provides fibers, which are less sensitive to macro-bending losses than presently known single-mode fibers with similar sized mode areas, and provides robust, single-mode, large-mode area fibers for long-distance optical transmission and fibers with special dispersion properties.

Claims45

Dependent claims

A micro-structured optical fibre for guiding light at an operating wavelength, said optical fibre having an axial direction and a cross section perpendicular to said axial direction, said optical fibre comprising:

a core region,
an inner cladding region surrounding said core region, said cladding region comprising a multiplicity of spaced apart inner cladding features that are elongated in the fibre axial direction and disposed in an inner cladding material, said inner cladding features having a smallest cross-sectional dimension, di,min, and a largest cross-sectional dimension, di,max, and having a centre-to-centre spacing, Λi, between two neighbouring inner cladding features,
an outer cladding region surrounding said inner cladding region, said outer cladding region comprising a multiplicity of spaced apart outer cladding features that are elongated in the fibre axial direction and disposed in an outer cladding material, at least part of said outer cladding features having a smallest cross-sectional dimension, do,min, and having a centre-to-centre spacing, Λo, between two neighbouring inner cladding features,
wherein
di,min is in the range from 0.35Λi to 0.50Λi,
do,min is in the range from 0.50Λo to 0.90Λo,
di,min is smaller than do,min, and
Λi is larger than 2.0 μm.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/416,023Filed 12 Nov 2001
Priority: DK 2000 0168610 Nov 2000
Published: US 2004/0052484 A118 Mar 2004
Granted: 15 Feb 2005
Term ends: Not estimatedThe source records don’t support an estimate.

Classification14 codes

G02B 6/024
Optical fibres with cladding with or without a coating: with polarisation maintaining properties
C03B 37/01205
Manufacture of preforms for drawing fibres or filaments: starting from tubes, rods, fibres or filaments
G02B 6/02338
Characterised by core or core-cladding interface features: structured core, e.g. core contains more than one material, non-constant refractive…
G02B 6/02357
Characterised by cladding features, i.e. light confining region: property of longitudinal structures or background material varies radially and/or…