+

WO2004019092A1 - Fibre en cristal photonique - Google Patents

Fibre en cristal photonique Download PDF

Info

Publication number
WO2004019092A1
WO2004019092A1 PCT/DK2003/000550 DK0300550W WO2004019092A1 WO 2004019092 A1 WO2004019092 A1 WO 2004019092A1 DK 0300550 W DK0300550 W DK 0300550W WO 2004019092 A1 WO2004019092 A1 WO 2004019092A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical fibre
cladding
core
features
core region
Prior art date
Application number
PCT/DK2003/000550
Other languages
English (en)
Inventor
Niels Asger Mortensen
Jes Broeng
Anders Petersson
Jacob Riis Folkenberg
Guillaume Vienne
Original Assignee
Crystal Fibre A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Crystal Fibre A/S filed Critical Crystal Fibre A/S
Priority to AU2003254639A priority Critical patent/AU2003254639A1/en
Publication of WO2004019092A1 publication Critical patent/WO2004019092A1/fr

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02295—Microstructured optical fibre
    • G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
    • G02B6/02319—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes characterised by core or core-cladding interface features
    • G02B6/02323—Core having lower refractive index than cladding, e.g. photonic band gap guiding
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02004—Optical fibres with cladding with or without a coating characterised by the core effective area or mode field radius
    • G02B6/02009—Large effective area or mode field radius, e.g. to reduce nonlinear effects in single mode fibres
    • G02B6/02014—Effective area greater than 60 square microns in the C band, i.e. 1530-1565 nm
    • G02B6/02019—Effective area greater than 90 square microns in the C band, i.e. 1530-1565 nm
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02295—Microstructured optical fibre
    • G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
    • G02B6/02319—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes characterised by core or core-cladding interface features
    • G02B6/02338—Structured core, e.g. core contains more than one material, non-constant refractive index distribution in core, asymmetric or non-circular elements in core unit, multiple cores, insertions between core and clad
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02295—Microstructured optical fibre
    • G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
    • G02B6/02342—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes characterised by cladding features, i.e. light confining region
    • G02B6/02347—Longitudinal structures arranged to form a regular periodic lattice, e.g. triangular, square, honeycomb unit cell repeated throughout cladding
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02295—Microstructured optical fibre
    • G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
    • G02B6/02342—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes characterised by cladding features, i.e. light confining region
    • G02B6/02347—Longitudinal structures arranged to form a regular periodic lattice, e.g. triangular, square, honeycomb unit cell repeated throughout cladding
    • G02B6/02352—Complex periodic lattices or multiple interpenetrating periodic lattices, e.g. unit cell having more than two materials, partially internally coated holes, for multiple bandgaps
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02295—Microstructured optical fibre
    • G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
    • G02B6/02342—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes characterised by cladding features, i.e. light confining region
    • G02B6/02357—Property of longitudinal structures or background material varies radially and/or azimuthally in the cladding, e.g. size, spacing, periodicity, shape, refractive index, graded index, quasiperiodic, quasicrystals
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02295—Microstructured optical fibre
    • G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
    • G02B6/02342—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes characterised by cladding features, i.e. light confining region
    • G02B6/02361—Longitudinal structures forming multiple layers around the core, e.g. arranged in multiple rings with each ring having longitudinal elements at substantially the same radial distance from the core, having rotational symmetry about the fibre axis
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02295—Microstructured optical fibre
    • G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
    • G02B6/02342—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes characterised by cladding features, i.e. light confining region
    • G02B6/02371—Cross section of longitudinal structures is non-circular
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02295—Microstructured optical fibre
    • G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
    • G02B6/02385—Comprising liquid, e.g. fluid filled holes

Definitions

  • the present invention relates to optical fibre waveguides, and use thereof in various applications, such as transmission optical fibres or speciality optical fibres in optical communication systems, and high power fibre lasers or amplifiers; in particular the invention relates to new designs of improved large mode area photonic crystal fibres that support a single mode or a few number of modes.
  • Optical fibres with large mode areas and single mode or few mode operations are desired within a vast number of technical areas, ranging from optical communications, sensor technology, spectroscopy, imaging, lithography, medicine, material processing, micro-machining, and many others.
  • it is desired to guide light through the optical fibre in a well-controlled manner such as for example in a single mode or a few modes and at the same time with a high intensity. This may either be for continuous wave or pulsed operation.
  • optical telecommunications for example, it is desired to transmit light signals at high bit rates over long distances. This requires short light pulses of high intensity and optical transmission fibres wherein little or no pulse distortion occurs. The most common causes of pulse distortion are dispersion and/or non-linear effects. Therefore, as optical transmission systems are being pushed towards higher bit rates, there is a need for developing optical fibres with improved properties with respect to dispersion and non-linearities.
  • dispersion effects in optical transmission links may be handled using various types of speciality compo- nents at discrete or extended lengths of a link - for example using dispersion and dispersion-slope compensating optical fibres.
  • non-linearities in optical fibres may be utilized for certain applications, such as for Raman amplification
  • a key to minimize non- linear effects is to increase the effective mode area of the optical fibre so that the power-density is lowered.
  • problems relate mainly to multi-mode operation and practical robustness in terms of low susceptibility to longitudinal non-uniformities. (these being, mainly, bending and structure variations due to imperfections during manufacturing and/or cabling) .
  • optical fibres in optical communica- tion systems operating at near-infrared wavelengths have, typically, a mode field diameter of up to around 10 ⁇ m - corresponding to an effective area of around 80 ⁇ m 2 .
  • Larger effective areas may, in theory, be realized, but generally effective areas of above 220 ⁇ m 2 are not pos- sible for practical fibres operating at near-infrared wavelengths due to the afore-mentioned issues and because such a fibre requires an extreme control of doping levels .
  • Fibres of this type comprise microstructured features that are elongated in the longitudinal direction of the fibres. These new fibres are referred to by a number of different names including photonic crystal fibres, microstructured fibres, holey fibres, photonic band gap fibres, and hole-assisted fibres.
  • PCF photonic crystal fibre
  • Optical fibres without microstructured features shall be referred to as standard optical fibres (such as traditional optical fibres that have been used and developed over several decades) .
  • PCFs may result in extremely large effective areas for single mode operation, e.g. areas of above 500 ⁇ m 2 , also for PCFs it turns out that problems such as bending losses and coupling losses, in practice, put limits to the achievable effective areas (see for example Monro et al . , Optics Letters, Vol. 26, No. 14, 2001 for an analysis of effective area with respect to macro-bending losses) .
  • these limits are not the same as known from standard optical fibres.
  • PCFs provide improvements compared to standard optical fibres in terms of larger effective areas as well as in terms of more broadband single mode or few mode operation. Therefore, a large research interest has been paid to PCFs within the last few years from a number of very different technical areas (see afore-mentioned areas) .
  • WO 99/00685 discloses a single mode PCF with a large core size and single mode operation. WO 99/00685 discloses how the core size of the PCF may be scaled to large dimensions while maintaining single mode operation.
  • a PCF comprising a core of uniform material, e.g. a solid silica core, and a cladding surrounding the core, said cladding comprising substantially perio- dically arranged air holes in a silica background material.
  • the optical fibre is allegedly suitable for high power transmission uses such as e.g. laser transmission for surgery, gas sensors, and communication network.
  • WO 02/39159 discloses PCFs with increased robustness to bending losses through the use of a microstructured cladding region with features of increasing size in directions away from the fibre centre, as well as PCFs utiliz- ing non-circular and non-equilateral outer shape of an outer cladding.
  • WO 02/14946 discloses a microstructured optical fibre comprising a solid core surrounded by a cladding of holes, said optical fibre being prepared by drawing preforms comprising capillaries of compound glasses including sulphides, halides, and heavy metal oxides.
  • WO 01/42831 discloses PCFs comprising a core region with a refractive index being between the refractive index of a cladding background material and cladding feature material (typically air holes) .
  • the PCFs have a short-wavelength cut-off for the fundamental mode.
  • PCF comprises a microstructured core region with 425 Yb doped elements placed in an irregular ensemble.
  • a high number of small, doped ele- ments are used in order to avoid any doped region regions themselves to form waveguides.
  • an optical fibre for transmitting light of at least one predetermined free-space optical wavelength ⁇ which optical fibre has a longitudinal direction and a cross-section perpendicular thereto, and which optical fibre comprises:
  • a microstructured cladding region said cladding region surrounding said core region and comprising microstructure cladding features arranged in a background cladding material, said microstructure cladding features having sizes d which are equal or different,
  • At least a number of said cladding features are being arranged proximal to said core region at a center-to-center cladding feature spacing ⁇ larger than 3 times ⁇ , and
  • said core region being surrounded by more than six innermost cladding features having a ratio d/ ⁇ less than 0.45,
  • the effective area and the MFD at ⁇ is significantly enhanced for a triangular core optical fibre compared to prior art hexagonal core optical fibres, and that the triangular core design is less susceptible to longitudinal non-uniformity, i.e. it is more robust, than the hexagonal core design.
  • the core region is designed for propagating light to be transmitted in the longitudinal direction of the optical fibre, said propagation being effected by providing a refractive index difference between the core region and said a microstructured cladding region surrounding it.
  • This refractive index difference may result by an effective refractive index difference between the core region and the microstructured cladding region.
  • the core region may take any shape suitable for the field distribution of the fundamental mode of the PCF and mode confinement by the inner most cladding features for providing a sufficiently low leakage of losses.
  • a core region having a substantially triangular shape is particularly preferred whereby increased robustness of a single mode optical fibre is obtained.
  • the core region can be seen as being positively defined by the presence of innermost cladding features, i.e. more than six e.g. nine or twelve innermost cladding features, or as being negatively defined by the absence of a number of cladding features, e.g. three cladding features.
  • said core region is formed by omission of three cladding features.
  • the area of the core region is selected according to the number of modes and level of intensity of the light to be transmitted.
  • the cladding features determine it and their arrangement as further disclosed below.
  • said core region has a geo- metric core area of more than 120 ⁇ m 2 , preferably more than 190 ⁇ m 2 , most preferred more than 220 ⁇ m 2 .
  • the core region may comprise any suitable material including a single material, a single material doped with dopants, a mixture of materials, a mixture of materials doped with dopants, and microstructured materials comprising core features.
  • said core region comprises at least one core feature, preferably three or more core features, most preferred more than four core features.
  • At least part of said core features is arranged to provide a substantially one- dimensional periodicity in a cross-section of said core region.
  • the number of innermost cladding features is more than 6, however, depending on the desired area of the core region, a larger number can be applied.
  • said number of innermost clad- ding features is equal to nine or twelve whereby optical fibres having particularly large mode field areas of more than 6 times ⁇ can be provided while maintaining robust transmission of light.
  • the size and arrangement of cladding features can vary within broad limits. In particular for confining propagation of light in the core region, size and arrangement of the innermost cladding features is selected.
  • the ratio d/ ⁇ is smaller than or about 0.25 whereby a condition of single mode is ensured.
  • not all cladding features need be of the same dimensions.
  • the innermost cladding features are selected and have one size whereas the size of outer cladding features and there between may have different sizes .
  • a majority of said micro- structure cladding features have a ratio d/ ⁇ of less than or about 0.30, preferably less than or about 0.25, most preferred in the range from 0.22 to 0.28 whereby it is obtained that cladding features arranged in the micro- structure may be present for different purposes, e.g. large area voids containing air or vacuum and smaller area solid features comprising doped materials.
  • substantially all microstructure cladding features have ratio d/ ⁇ of less than or about 0.30, preferably less than or about 0.25, most preferred in the range from 0.22 to 0.28 whereby it is obtained that an optical fibre of substantially uni- form microstructured cladding can be obtained.
  • ratio d/ ⁇ of less than or about 0.30, preferably less than or about 0.25, most preferred in the range from 0.22 to 0.28 whereby it is obtained that an optical fibre of substantially uni- form microstructured cladding can be obtained.
  • Such a uniformity may, for example, be preferred for facilitate production of the optical fibre using only one type of capillary tubes for forming the microstructured cladding.
  • the mode field of the optical fibre is adapted to the application, e.g. to the wavelength to be transmitted by the optical fibre.
  • the optical fibre has a mode field diameter equal to or larger than 6 ⁇ whereby increased robustness compared to prior art microstructured fibres is obtained.
  • the optical fibre exhibits a parameter 0.7(3 ⁇ -d) which is equal to or larger than 6 ⁇ whereby a simplified expression for the mode field diameter relationship and wavelength is obtained.
  • the cladding features can be arranged in any suitable structure that provides index guiding of the light in the core region.
  • said microstructure cladding features are arranged in a periodic structure.
  • said microstructure cladding features are arranged in concentric rings around said core region.
  • optical fibre comprises material known in the art
  • said core region, said micro- structured cladding region, or both comprises silica whereby a well-known optical fibre material for which production techniques exists can be applied.
  • the optical fibre may, however, comprise different materials for its components.
  • said core region, said microstructured cladding region, or both comprises silica and/or silica including one or more co-dopant materials, preferably a material selected from the group consisting of Ge, Al, B, or F (or other materials) , or a combination thereof.
  • the cladding region may comprise any suitable optical fibre material, however, specific properties may be obtained by selecting specific cladding features.
  • said micro- structure cladding features are selected from the group consisting of solids, liquids, voids, and combinations thereof.
  • said voids comprises air, vacuum, liquids, solids, or a combination thereof.
  • said voids are filled with liquid, or a polymer.
  • the optical fibre comprises an active material for providing lasing action.
  • said core region and/or at least a part of said cladding background material comprises an active material, preferably silica doped with a rare earth element, most preferred silica doped with Er, Yb, or Nd, or a combination thereof.
  • said core region and/or at least a part of said cladding background material comprises co- dopant materials, preferably a material selected from the group consisting Ge, Al, B, or F, (or other materials) or a combination thereof.
  • the optical fibre used depends on the required wavelength or range of wavelength to be transmitted.
  • the predetermined wavelength ⁇ is in the range from ⁇ i to ⁇ 2 , where ⁇ i is less than or equal to ⁇ 2 , and ⁇ i and ⁇ 2 are in the range 0.1 ⁇ m to 2.0 ⁇ m.
  • said ⁇ i and ⁇ 2 are in the range from 0.4 ⁇ m to 1.7 ⁇ m, preferably in the range from 1.3 ⁇ m to 1.7 ⁇ m, most preferred in the range from 1.5 ⁇ m to 1.6 ⁇ m whereby the optical fibre may be used for applications using visible to near-infrared light.
  • ⁇ is larger than 3 times ⁇ 2 whereby it is obtained that the optical fibre is more robust than prior art microstructure fibres in the whole wavelength range from ⁇ i to ⁇ 2 (since ⁇ i is smaller than ⁇ 2 and therefore it is also valid that ⁇ is larger than 3 times any wavelength down to ⁇ i) .
  • an optical fibre according to the present invention or an optical fibre produced in a method according to the invention in an optical communi- cation system, in an optical fibre laser, or in an optical fibre amplifier, or in one or more parts thereof.
  • the term "light” designates electromagnetic radiation, in particular light having a wave length in the range from 0.1 ⁇ m to 30 ⁇ m.
  • size is intended to designate a size parameter of a structural element of the optical fibre, e.g. the diameter of a cladding feature such as a hole.
  • refractive index is intended to mean the conventional refractive index of a homogeneous material.
  • Most relevant materials for optical fibre production e.g. silica
  • the effective refractive index is very dependent on the morphology of the material.
  • the effective refractive index of a micro- structure is strongly wavelength dependent - much stronger than the individual refractive index of any of the materials constituting the components of the microstructure.
  • Determination of the effective refractive index of a given microstructure at a given wavelength is known to those skilled in the art (see e.g. the method disclosed by Jouannopoulos et al, "Photonic Crystals", Princeton University Press, 1995, or the method disclosed by Broeng et al, Optical Fiber Technology, Vol. 5, pp. 305-330, 1999) .
  • a directly measurable quantity is the so-called "filling fraction" which is defined as the ratio of the volume of disposed features, or micro- structure elements, in a microstructure relative to the total volume of a microstructure.
  • the filling fraction may be determined from direct inspection of the cross-section of the optical fibre.
  • An effective refractive index should generally be determined at a given operational wavelength or at a predetermined wavelength.
  • the term "effective area" is intended to designate the effective area of a fundamental mode at a given wavelength that is guided in the core of a fibre.
  • the effec- tive area is defined as [see e.g. N.A. Mortensen, Optics Express, Vol. 10, pp. 341-348 (2002)]:
  • the lowest order cladding mode is also known as the fundamental space filling mode of the cladding (see e.g. T.A. Birks et al . , Optics Letters, Vol. 22, pp. 961-963, 1997). If L n is the length scale for longitudinal non-uniformities and ⁇ the wavelength then a critical- loss criterion can be formulated as a competition of length scales [J.D. Love, IEE Proceedings - J. Optoelectronics, Vol. 136, pp. 225-228 (1989) ] ;
  • the susceptibility of a PCF to longitudinal non- uniformities can be expressed by the coupling length ⁇ ; the lower a value of the coupling length the lower a loss can in general be expected.
  • Fig. 1(a) shows schematically an example of a PCF with a design according to the present invention.
  • Fig. 1(b) shows a microscope photograph of a produced fibre with such a design.
  • Fig. 2(a) shows experimentally observed near-field distribution of the fundamental mode of the fibre in Fig. 1(b) at a wavelength of 980 nm.
  • Figs. 2(b) and 2(c) show simulated results of the same near-field for a linear and logarithmic intensity scale, respectively.
  • Fig. 3(a) shows schematically a prior art PCF with a core that is formed by omitting one air hole. The core has a substantially hexagonal shape.
  • Fig. 3(b) is shown schematically a cross sectional design of an optical fibre according to the present invention, this PCF has a substantially triangular shaped core that may be formed by omitting three air holes.
  • Fig. 3(c) shows schematically three omitted cladding fea- tures. The three omitted features are placed substantially in a triangle.
  • Figs. 4(a) and 4 (b)_ show coupling length versus wavelength for PCFs with hexagonal (dashed lines) and trian- gular (solid lines) cores.
  • the wavelength is normalized by the pitch and in Fig. 4(b) the wavelength is normalized by the edge-to-edge separation of the air holes .
  • Fig. 5(a) shows the effective area and Fig. 5(b) shows the mode-field diameter versus wavelength for PCFs with hexagonal (dashed lines) and triangular (solid lines) cores .
  • Fig. 6(a) shows the effective area versus coupling length and Fig. 6(b) shows the mode-field diameter versus coupling length for PCFs with hexagonal (dashed lines) and triangular (solid lines) cores.
  • Fig. 7 shows simulated MFD as function of pitch for triangular core design - as well as a simple rule-of- thumb calculation of MFD as function of pitch and hole size .
  • Fig. 8(a) shows a definition of geometric core area of a hexagonal core PCF according to prior art and Fig. 8(b) shows a definition of geometric core area of a triangular core of a preferred embodiment of a PCF according to the present invention.
  • Fig. 9(a) shows further examples of preferred embodiments of PCFs according to the present invention having cladding features placed substantially periodically.
  • Fig. 9(b) shows an example of a preferred optical fibre according to the present invention having cladding features placed in substantially concentric circles.
  • Fig. 10 shows cut-off properties of preferred embodiments of produced PCFs according to the present invention for different cladding feature sizes.
  • Fig. 11(a) shows the waveguide group-velocity dispersion versus wavelength
  • Fig. 11(b) shows the waveguide group- velocity dispersion versus effective area
  • Fig. 11(c) shows the waveguide group-velocity dispersion versus mode-field diameter
  • Fig. 11(d) shows the waveguide group-velocity dispersion versus coupling length for preferred embodiments of PCFs with hexagonal (dashed lines) and triangular (solid lines) cores.
  • Fig. 12 shows an example of a preferred embodiment of a PCF according to the present invention comprising low- index type core features.
  • Fig. 13 shows mode index as function of normalized wavelength of the fundamental mode, the 2. order mode and the lowest order cladding mode of the PCF shown in Fig. 12.
  • Fig. 14 shows a simulation of MFD as function of pitch for the PCF shown in Fig. 1(a), the PCF in Fig. 12 as well as for a prior art PCF with an un-doped hexagonal core .
  • Fig. 15(a) shows schematically a part of the inner cross- section of a preferred embodiment of a PCF according to the present invention, where the core region comprises three core elements each having microstructured features.
  • Fig. 15(b) shows a close-up view on one of the core elements .
  • Fig. 16 shows a schematic example of a preferred embodiment of a PCF according to the present invention for use as cladding pumped fibre for laser or amplifier applications.
  • the PCF comprises an air-clad region in an outer cladding.
  • Fig. 17 (a) shows a schematic example of a preferred em- bodiment of a preform for producing a fibre according to the present invention, where the core is placed substantially in the center of the PCF.
  • Fig. 17 (b) shows a similar schematic example of a preferred embodiment of a preform, but with a core region placed in a non-central position in the PCF.
  • Fig. 18 shows experimental data of attenuation for a prior art PCF and a preferred embodiment of a PCF according to the present invention in the case where the two types of PCFs have substantially similar susceptibility to longitudinal non-uniformities.
  • the PCF according to the present invention has a MFD of about 12.0 ⁇ m, whereas the prior art PCF has a MFD of around 10.5 ⁇ m.
  • Fig. 19 shows a microscope photograph of a preferred embodiment of a produced PCF according to the present invention. The photograph shows that for real fibres some dimensions of geometric features in the cross-section may vary - such as the hole size that is seen to decrease in size away from the core.
  • Fig. 1 (a) schematically depicts the cross-section of an exemplary preferred embodiment of an optical fibre 10 according to the present invention.
  • the optical fibre comprises a core region 11 for propagating the light to be transmitted in the longitudinal direction of the optical fibre, here a triangularly shaped core region, a microstructured cladding region surrounding said core region and comprising microstructured cladding elements 12, or so-called cladding features 12, here elongated cladding features of equal size the inner most of which shape the extent of the core region, said cladding features being placed in a background cladding material 13 in the cladding, and an over-cladding region 14.
  • nine innermost cladding features surround the core region, here defining a substantially triangular shape that is formed by the position of the innermost cladding features.
  • Fig. 1(b) shows a microscope photograph of the cross-section of a preferred embodiment of a real PCF according to the present invention.
  • the PCFs has a core region of similar material as the cladding background material - in this case pure silica.
  • the optical fibre has a centre-to- centre cladding feature spacing, the so-called pitch, ⁇ , of about 6 ⁇ m and a cladding feature size, here hole diameter, d, of about 1.5 ⁇ m.
  • the optical fibre in Fig. 1(b) shows a cross-sectional view of a microscope photograph of a produced optical fibre that has been characterized experimentally to be single mode over a broad wavelength range of about 400 nm to 1700 nm.
  • Fig. 2 illustrates the field distribution of the fundamental mode of- the PCF shown in Fig. 1(b). At a wavelength of 980 nm, Fig. 2(a) shows the experimentally observed near-field.
  • Figs. 2(b) and 2(c) shows computer simulations of the same near-field on a linear and logarithmic intensity scale, respectively.
  • the computer simulations were performed using a program described in previously mentioned Johnson et al . reference.
  • the experimental and linear near-field intensities demonstrate a substantial triangular shape of the fundamental mode and a mode confinement defined substantially by nine innermost cladding features .
  • the logarithmic scaled graph facilitates observation of low-intensity parts of the mode field distribution.
  • This graph confirms that the number of cladding feature layers surrounding the core contributes in providing low leakage losses. Consequently, in a prefer- red embodiment, the number of cladding feature layers is maximised for a given outer diameter of the PCF, typically 125 ⁇ m for optical fibres used in telecommunications.
  • Fig. 3(a) shows schematically an inner, cross-sectional part of a prior art PCF with a substantially hexagonal core 30.
  • the core may be defined as a defect in the otherwise periodic cladding structure, where the defect is formed by omission of a single cladding feature.
  • six innermost cladding features 31 can define the core.
  • This type of PCF shall hereinafter be referred to as a hexagonal core PCF.
  • Fig. 3(b) shows similarly a schematic illustration of an inner, cross-sectional part of a preferred embodiment of a PCF according to the present invention - as shown in Fig. 1.
  • the core region 35 may be seen as a defect being formed by omission of three cladding features 37 (see Fig. 3(c)) or as being defined by nine innermost cladding features 36.
  • This type of PCF shall hereinafter be refer- red to as a triangular core PCF.
  • Both optical fibres may have similar core materials 30,35 and similar cladding background materials 32,37.
  • the two PCFs have cladding features that are positioned periodically (in this case in a close-packed arrangement, also known as a triangular structure or hexagonal structure) .
  • the present invention is, however, not limited to periodic cladding structures - and examples of this are presented for the embodiment shown in Fig. 9(b) .
  • the PCF technology is known to have a high potential for the realization of highly -birefringent optical fibres
  • the hole-diameter to pitch ratio d/ ⁇ can be chosen such that a defect in the cladding structure supports only a single (doubly degenerate) mode for all wavelengths, i.e. endlessly single mode operation [T.A. Birks et al . , Optics Letters, Vol. 22, pp. 961-963 (1997)].
  • the hexagonal core PCF as described above, the PCF will be endlessly single- mode for d/ ⁇ ⁇ 0.45 [see e . g. J. Broeng et al . , Optical Fiber Technology, Vol. 5, pp. 305-330 (1999)].
  • a second-order mode will be guided at short wavelengths and the corresponding cut-of wavelength increases with increasing air-hole size [N.A. Mortensen, Optics Express, Vol. 10, pp. 341-348 (2002)].
  • the optical fibre surprisingly turns out to be endlessly single-mode for a cladding feature size, here a hole size, d/ ⁇ , of approximately 0.25.
  • a hole size, d/ ⁇ of approximately 0.25.
  • Many other materials than air may be used in the cladding features, such as gasses or vacuum that will have a refractive index close to that of air.
  • d/ ⁇ 0.25 will also be a representative value for endlessly single mode operation.
  • materials of the cladding features e.g.
  • the refractive index of the cladding feature material is larger than 1 (the refractive index of vacuum, air, or another gas), and a d/ ⁇ value of larger than 0.25 may yield end- lessly single mode operation.
  • the cladding features are made using glass of lower refractive index than the background material (see for example US 6 243 522 for a general description of all-glass microstructured fibres, including preferred materials and methods ' of their production/fabrication) , and d/ ⁇ may be as large as 0.45 for endlessly single mode operation. Naturally, to allow a few number of modes, d/ ⁇ may be even larger.
  • Optical fibres according to the present invention may also be realized using polymer (s) as background material (see for example WO 02/16984 for general description of polymer microstructured fibres, including preferred materials and methods of their production/- fabrication) .
  • the MFD compares well to ⁇ [N.A. Mortensen, Optics Express, Vol. 10, pp. 341-348 (2002)] for large mode area applications, i.e. for optical fibres with an MFD of a magnitude of several times the free-space optical wavelength, ⁇ , e.g. about 6 ⁇ or larger.
  • Both optical fibres will be assumed to be single material optical fibres that are realized in pure silica, and a refractive index of 1.444 will be used as a representative value.
  • the cladding features are assumed to be air (or vacuum) with a refractive index of 1.
  • Fig. (a) shows the normalized coupling length, ⁇ / ⁇ , as a function of normalized wavelength, ⁇ / ⁇ , for a prior art hexagonal core PCF (dashed line) and for a triangular core preferred PCF (solid line) according to the present invention.
  • a triangular core preferred PCF solid line
  • Fig. 4(b) is shown the same data of Fig. 4(a), but with the wavelength normalized by the edge-to-edge separation ⁇ -d of the cladding features, here air holes; re- scaling makes the two curves coincide in the short wavelength limit.
  • Fig. 4(b) shows that ⁇ -d, rather than the air-filling fraction, is a parameter to minimize when designing low-loss large-mode area PCFs.
  • Fig. 5 is shown the effective area and the MFD as a function of normalized wavelength. As seen, the effective area is significantly enhanced for the optical fibre according the present invention (triangular core) as compared to the prior art fibre (hexagonal core) .
  • the fibre according to this preferred embodiment is further advantageous compared to prior art fibres.
  • MFD is equal to or larger than 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, and 30 ⁇ m.
  • the here-disclosed PCF with a triangular core can provide an effective area of 90.8 ⁇ m 2 (and a MFD of 10.8 ⁇ m) , but still with the same susceptibility to longitudinal non-uniformities as for the PCF with a hexagonal core. This corresponds to an increase in effective area by close to 16%.
  • the corre- sponding effective area of the PCF with a triangular core becomes 360.6 ⁇ m 2 , i.e. an increase by close to 15%.
  • Fig. 7 shows a computer simulation of MFD as a function of pitch, ⁇ , for the triangu- lar PCF of Fig. 4-6 at a wavelength of 1.1 ⁇ m.
  • ⁇ a function of pitch
  • the fibre is found to have MFD that is close to 2 ⁇ .
  • the triangular core PCF may be found to be advantageous in the case of ⁇ larger than about 3 ⁇ .
  • a fibre according to the present invention has core with larger area relative to the width ⁇ -d compared to a hexagonal core, prior art PCF.
  • a geometric core area A geo of PCFs as illustrated in Figs. 8(a) and 8(b) (this area is not identical to the effective mode area A eff that is used elsewhere in the application) .
  • this area is not identical to the effective mode area A eff that is used elsewhere in the application.
  • a core area A geo , hex can be defined for the hexagonal core PCF equal to
  • a polygon 82 expanded by centres of innermost cladding features 83 for the triangular core PCF has six sides of non-equal lengths, but the core region may still be considered as substantially triangular.
  • the core area A geo , tr ⁇ of the triangular core PCF may, thus, be found from geometrical considerations to be equal to:
  • the triangular core design provides an area of about 195 ⁇ m 2
  • the hexagonal core design provides a core area of about 90 ⁇ m 2 .
  • the reason for the larger core area relative to ⁇ -d for the triangular core PCF as compared to the hexagonal core PCF is the number of innermost cladding features surrounding the core region.
  • PCF core designs providing more than 6, such as 9 or 12 innermost cladding features may be advantageous for large mode area PCF applications .
  • FIG. 9 shows ex- amples of PCFs according to the present invention having substantially periodic cladding features
  • Fig. 9(b) shows an example of a PCF 90 having non-periodic cladding features 92 - in this example the cladding features are placed on substantially concentric circles 93 surrounding the core region 91.
  • a different maximum hole size for endlessly single mode operation may be found.
  • the maximum hole size for the designs shown in Fig. 9(a) are indicated in the figure. These hole sizes, d/ ⁇ , are -0.18, -0.15, and -0.15 for the PCFs with 4, 6, and 7 missing cladding features forming the core region, respectively.
  • the endlessly single mode crite- rion in terms of hole size may be different.
  • the triangular core PCF may support one or more higher order modes, but it may also be operated in single mode regime (such as known from standard fibres).
  • Fig. 10 shows cut-off pro- perties of produced PCFs with a triangular design for different cladding feature sizes.
  • the variation in hole size is mainly a result of structure variations during production.
  • the PCF with larger hole sizes may be operated in a single mode for wavelengths larger than approximately 990 nm, and the PCF with smaller holes may be operated in a single mode for wavelengths longer than approximately 830 nm.
  • the cut-off wavelength may be scaled by scaling the pitch of the structure, such that for larger pitch, a cut-off at longer wavelengths may be realized.
  • optical fibre in a multi-mode regime, similar to the method for example described in US 6 400 866, where two or more optical signals are transmitted at the same optical wavelength, but in two or more different modes of the optical fibre.
  • mode selection may allow the laser to operate in a fundamental mode, although the optical fibre, in theory, supports several modes. For example, different loss levels of the modes may perform selection.
  • the present invention is not restricted to fibres with d/ ⁇ of 0.25 or less.
  • PCFs according to the present invention may be used in optical communication systems.
  • dispersion is an important optical fibre parameter and Fig. 11 facilitates to design a PCF according to the present invention with specific dispersion properties.
  • Fig. 11(a) shows the waveguide group-velocity dispersion versus wavelength
  • Fig. 11(b) shows the waveguide group-velocity dispersion versus effective area
  • Fig. 11(c) shows the waveguide group- velocity dispersion versus mode-field diameter
  • Fig. 11(a) shows the waveguide group-velocity dispersion versus wavelength
  • Fig. 11(b) shows the waveguide group-velocity dispersion versus effective area
  • Fig. 11(c) shows the waveguide group- velocity dispersion versus mode-field diameter
  • 11(d) shows the waveguide group-velocity dispersion versus coupling length for PCFs with hexagonal (dashed lines) and triangular (solid lines) cores.
  • the waveguide dispersion has been calculated in the case of no material dispersion.
  • the total fibre dispersion may as a good approximation be determined as the sum of material dispersion and waveguide dispersion.
  • a single material e.g.
  • the optical fibre will have a waveguide dispersion of about 3 ps/nm/km and a total dispersion of about 20 ps/nm/km.
  • the present invention also covers optical fibres of non- single materials, such as fibres comprising various types of dopants in the cladding region or parts thereof, and/- or in the core region or parts thereof. Also the present invention covers optical fibres where the cladding features comprise various types of materials, such as polymers, semiconductors, crystalline materials, etc.
  • various doping profiles may be used in the fibre core to provide further flexibility in tailoring dispersion and/or cut-off properties of the fibres.
  • Dopants may also be used to provide active regions in the PCFs, for example for making optical fibres for lasers and amplifiers applications.
  • Fig. 12 shows an example of a preferred embodiment of a PCF according to the present invention comprising low- index type core features.
  • the low-index features may, for example, be introduced to control the cut-off properties of the optical fibre.
  • the cut-off properties of a specific PCF with a design as in Fig. 12 are illustrated in Fig. 13.
  • Fig. 13 shows mode index as function of normalized wavelength of fundamental, 2. order and lowest order cladding mode.
  • the fibre has a cut-off of the first higher order mode (2. order mode) at a normalized wavelength, ⁇ / ⁇ , of about 0.085.
  • the optical fibre has furthermore a cut-off of the fundamental mode at a normalized wavelength of about 0.050.
  • a PCF with ⁇ of 20.0 ⁇ m will, therefore, be single mode at a wavelength of 1.0 ⁇ m to 1.7 ⁇ m.
  • the PCF simulated in Fig. 13 has d/ ⁇ of 0.30.
  • this hole size is larger than the endlessly single mode limit for a single material PCF, the fibre is observed to cut-off even the fundamental due to the low-index features in the core.
  • Fig. 14 shows a simulation of MFD as function of pitch for the PCF in Fig. 13, for the PCF in Fig. 1, panel (a), and for a prior art PCF with an undoped hexagonal core.
  • the hole size d/ ⁇ of the three fibres is 0.30, 0.22 and 0.45, respectively.
  • MFD is significantly larger for a given pitch for the two triangular core PCF compared to the prior art PCF.
  • a further advantage may be realized from Fig. 2 panel (c) and Fig. 14.
  • the core region is approximated to a diameter of about 30 ⁇ m and the overcladding region to a radial width of about 20 ⁇ m (in total contributing to 40 ⁇ m of the outer diameter) .
  • the (smaller) triangular core PCF therefore, requires less glass for production.
  • the triangular PCF may prove a cheaper optical fibre to produce in terms of raw material.
  • the present invention therefore, also provides new, large mode area PCFs that may be cheaper to produce that prior art PCFs.
  • ef- fective refractive index of the core region may be tailored as a function of wavelength. This may, for example, be done using a number of microstructured features in the core region as sown schematically in Fig. 15.
  • Fig. 15(a) the figure shows schematically a part 150 of the inner cross-section of a PCF according to the present invention, where the core region is surrounded by nine innermost cladding features 151 and it comprises three core elements 152 each having microstructured features 152.
  • Fig 15(b) shows a close-up view on one of the core elements 155 to il- lustrated that a core element may comprise a large number of high-index elements 156 and low-index elements 157.
  • the low-index and/or the high-index elements may optionally be of similar material as the core and/or cladding background material, or they may be of a different mate- rial with similar refractive index as one or both background materials.
  • the high- index features are positioned in substantially hexagonal concentric layers of high- and low-index type of silica rods .
  • the core comprises micro- structured features that are placed in a substantially one dimensionally periodic structure.
  • This arrangement may, for example, be accomplished by having low-index and high-index core features placed in a layered manner as described in Danish Patent Application PA 2002 00787 (the priority of which is being claimed in PCT/DK03/00345) that is incorporated herein by reference.
  • Fig. 16 shows a schematic example of a preferred embodiment of a PCF according to the present invention that may be used as a cladding pumped fibre for laser or amplifier applications.
  • the PCF comprises an air-clad region in an outer cladding.
  • the PCF 160 comprises a triangular core design with three microstructured core elements 161 and an inner microstructured cladding region 162 and an outer cladding region comprising an air-clad region 163.
  • Fig. 17(a) A number of these methods are based on stacking of rods or canes to form a preform and drawing this into optical fibre using a conventional drawing tower.
  • Examples of preforms for optical fibres according to the present invention are illustrated in Fig. 17.
  • the preform 170 in Fig. 17(a) comprises three pure silica rods 171 that will form the core. These rods are surrounded by a number of silica tubes 172 that will form a periodic structure of the inner cladding region.
  • the stack of rods and tubes is placed in an overcladding tube 173.
  • the preform may further comprise various types of filling/stuffing/buffer elements, such as for example rods to fill out the gaps 174.
  • the overcladding tube usually acts as an outer cladding region providing a desired outer diameter of the final fibre as well as mechanical robustness of the fibre.
  • outer claddings are also covered by the present invention, such as outer claddings comprising an air-clad layer and a solid part - as for example described in US 5 907 652 the content of which regarding further information on drawing optical fibres with micro- structured features is incorporated be reference.
  • a lower than atmospheric pressure may be apply inside the overcladding tube in order for the small interstitial voids between the rods and tubes to col- lapse. In this manner, the rods and tubes may form a close packed, periodic arrangement.
  • the preform in Fig. 17 comprises a relatively low number of periods surrounding the core.
  • the preform may preferably be processed prior to fibre drawing where the preform is for example placed in a lathe and heated to a temperature such that the overcladding tube collapses and fixates the rods and tubes.
  • the method of stacking rods may also be applied, using appropriate modifications, to other material systems, such as for example polymers or non-silica glasses.
  • Fig. 17(b) shows a similar schematic example as in Fig. 17(a), but for a preform where the core region 175 is placed in a non-central position in the PCF. Such a position may be preferred for improved pump absorption in cladding pumped fibre applications.
  • Fig. 15 and 16 it may be advantageous for to pre-produce the element (s) of the core region by stacking high- and low-index features in a regular manner inside an overcladding tube.
  • This overcladding tube may then be drawn to a (solid) core rod with the inner structure being regular in at least a part of the cross-section.
  • the resulting core rod may hereafter be used in a preform for a microstructured fibre in a manner as described above.
  • the preform may be prepared by controlled heat treatment, optionally under pressure and/or vacuum of the capillary tubes and the interstitial voids between the tubes.
  • a skilled person would know how to calibrate the parameters of the preparation, e.g. the temperature, pressure, vac- uum, with respect to the glass of the capillaries ap- plied, e.g. its thickness, viscosity, softness, etc., see e.g. WO 02/14946.
  • non-silica based PCFs other principles than the ones described above may be used for production.
  • crystalline or poly-crystalline materials such as for example a silver halide, e.g. a solution of AgClo. 5 Bro.5A a combination of methods known in the art may be used.
  • Preform elements of silver halide materials can be extruded by a modified extrusion method disclosed in US 5 342 022
  • the PCF is made from pure silica and the cladding features are air-filled voids.
  • the core region has a substantially triangular shape.
  • the core region may be viewed as formed by omission of three cladding features.
  • Surrounding the core region - or a centre of the core region - are nine innermost cladding features.
  • the PCF comprises cladding features with a pitch, ⁇ , of about 6 ⁇ m and with a diameter, d, of about 1.5 ⁇ m.
  • the PCF comprises cladding features with a relative diameter, d/ ⁇ , of about 0.25.
  • the PCF has nine innermost cladding features with d/ ⁇ of about 0.25.
  • ⁇ free-space wavelength
  • the PCF has MFD of about 12 ⁇ m.
  • MFD is approximately equal to 2 ⁇ or approximately equal to 0.7(3 ⁇ -d) .
  • the PCF has MFD of more than 6 ⁇ .
  • the PCF has ⁇ of more than 3 ⁇ .
  • the PCF has 0.7(3 ⁇ -d) of more than 6 ⁇ .
  • ⁇ shorter than about 2.0 ⁇ m, such as ⁇ from 0.4 ⁇ m to 1.7 ⁇ m
  • PCF has MFD of more than 6 ⁇ , ⁇ of more than 3 ⁇ , and 0.7(3 ⁇ -d) of more than 6 ⁇ .
  • the produced optical fibre transmits light robustly from visible wavelengths of at least 600 nm to at least 1.6 ⁇ m.
  • the optical fibre was prepared by a method as described above, wherein packaging of preform elements was adapted to provide the preferred design of core region and micro- structure cladding elements in a background cladding material, here a triangular core of silica surrounded by a silica background material with a closed packed periodic structure of microstructure cladding elements in form of holes, said triangular core being surrounded by nine innermost cladding element, and about 8 layers of cladding elements.
  • a preform was prepared by stacking 249 capillary tubes of silica (glass tubes of silica material with trademark F300 from Hereaus) ) to form the cladding region and three rods of silica (glass rods of silica material with trademark F300 from Hereaus) to form the core region as shown in Fig. 17 (a) .
  • the capillary tubes have an outer diameter of 1.7 mm and an inner diameter of 0.6 mm.
  • the rods have similar outer diameter as the capillary tubes.
  • the capil- lary tubes and rods where stacked in a close packed manner and placed in an overcladding tube of silica (trademark F300 from Hereaus) with inner dimensions of 30 mm and outer diameter of 35 mm.
  • a number of smaller rods of silica where used to partially fill gaps between the stack of capillary tubes/rods and the overcladding tube.
  • Dimensions of the capillary tubes, the rods, and the overcladding tube varied within normal production limits known to a skilled person, e.g. generally up to a few percent. Less variability can be obtained by individual selection of the preform elements/components.
  • the preform was placed in a conventional drawing tower and vacuum was applied to the "interstitial region" between the capillary tubes.
  • the preform was drawn to a "preform cane" with an outer diameter of 5.7 mm.
  • An atmospheric pressure in the capillary tubes was used to prevent collapse and keep them open during drawing.
  • the preform cane was afterwards overcladded with a tube of quartz glass having an outer diameter of 10.0 mm and an inner diameter of 6.0 mm.
  • This new production preform was then drawn into a PCF.
  • a vacuum was applied to the gap between the overcladding tube and the preform cane in order to seal the overclad- ding tube and the preform rod together during drawing.
  • the pressure was applied to the inside of the capillary tubes of the preform cane by mounting a pressure chamber on the top end of the preform cane and the pressure was controlled to yield a final size to pitch ratio of the cladding elements, here holes, of d/ ⁇ of about 0.25.
  • the drawing temperature was about 1900 degrees Celcius and the drawing speed was around 30 m/min.
  • the PCF was coated with an acrylate material using a standard UV-curing coating technique. The hole size of the PCF was inspected visually during drawing of the fibre using an optical microscope.
  • the optical fibre was wound up using conventional optical fibre spools.
  • the specifically desired dimensions of the core region, the micro structure features, and their center-to-center distance are achieved by calibration of production/manufacturing parameters such as temperatures, fibre pulling speed and preform feeding rates, etc. for producing PCFs and preforms comprising capillary tubes, rods and cladding tubes of given dimensions all of which production/manufacturing parameters and preform element dimensions are known to and/or can be assessed e.g. ex- perimentally by a person skilled in the art.
  • the two fibres have substantially similar attenuation curves for the investigated wavelengths. This imply that they have similar sensitivity to longitudinal changes, i.e. that they have similar susceptibilities to longitudinal non-uniformities.
  • the triangular core PCF according to the present invention has a larger mode area MFD of about 12.0 ⁇ m, whereas the prior art PCF has a smaller MFD of around 10.5 ⁇ m.
  • both PCFs were spooled on optical fibre drums with a radius of 32 cm.
  • Fig. 19 shows another microscope photograph of a preferred embodiment of a produced PCF according to the present invention.
  • the photograph shows that for real optical fibres some variation of dimensions of geometric features in the cross-section can occur.
  • the hole size can decrease in size away from the core.
  • the further away from the core, a feature in a PCF is placed the smaller is the influence of that feature on the performance of the PCF (in terms of e.g. leakage losses, dispersion, etc.).
  • the largest size variation is for the outermost cladding features, whereas the nine innermost cladding features have a smaller variation.
  • it is desired to most accurately control the innermost cladding features and a larger variation may be tolerated for the outer cladding features.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)

Abstract

La présente invention concerne une fibre optique améliorée à large bande, monomode ou multimode, résistant aux pertes, telles que les pertes par courbure et les pertes de couplage. La fibre optique est destinée à la transmission de lumière à au moins une longueur d'onde optique μ. La fibre optique (10) possède un sens longitudinal et un sens transversal perpendiculaire au sens longitudinal. La fibre optique comprend un noyau (11) et une gaine microstructurée. La gaine entoure le noyau et comprend des éléments de gaine microstructurés (12) disposés dans un matériau de support (13). Une pluralité de ces éléments de gaine microstructurés sont de taille d sensiblement identique, les éléments de gaine étant généralement circulaires en coupe et d étant égal au diamètre des éléments de gaine. Au moins un nombre donné d'éléments de gaine sont situés à proximité du noyau, à une distance de centre à centre de l'espace entre les éléments de gaine Μ supérieure à 3 fois μ. Le noyau est entouré par plus de six des éléments de gaine les plus à l'intérieur ayant un rapport d/Μ inférieur à 0,45.
PCT/DK2003/000550 2002-08-20 2003-08-19 Fibre en cristal photonique WO2004019092A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003254639A AU2003254639A1 (en) 2002-08-20 2003-08-19 Photonic crystal fibre

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DKPA200201231 2002-08-20
DKPA200201231 2002-08-20
US40475002P 2002-08-21 2002-08-21
US60/404,750 2002-08-21

Publications (1)

Publication Number Publication Date
WO2004019092A1 true WO2004019092A1 (fr) 2004-03-04

Family

ID=31947814

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK2003/000550 WO2004019092A1 (fr) 2002-08-20 2003-08-19 Fibre en cristal photonique

Country Status (2)

Country Link
AU (1) AU2003254639A1 (fr)
WO (1) WO2004019092A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006099017A1 (fr) * 2005-03-11 2006-09-21 Massachusetts Institute Of Technology Fibre optique microstructuree a zone en mode large
US7787729B2 (en) 2005-05-20 2010-08-31 Imra America, Inc. Single mode propagation in fibers and rods with large leakage channels
US8755658B2 (en) 2007-02-15 2014-06-17 Institut National D'optique Archimedean-lattice microstructured optical fiber
US8995051B2 (en) 2007-09-26 2015-03-31 Imra America, Inc. Glass large-core optical fibers
WO2016206700A1 (fr) 2015-06-25 2016-12-29 Nkt Photonics A/S Ensemble fibres de distribution et source à large bande
US10197727B2 (en) 2004-01-16 2019-02-05 Imra America, Inc. Large core holey fibers
PL424807A1 (pl) * 2018-03-08 2019-09-09 Polskie Centrum Fotoniki I Światłowodów Światłowodowy czujnik zgięć oraz sposób pomiaru zgięć

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6243522B1 (en) * 1998-12-21 2001-06-05 Corning Incorporated Photonic crystal fiber
WO2002039159A1 (fr) * 2000-11-10 2002-05-16 Crystal Fibre A/S Fibres optiques presentant des proprietes speciales de dispersion et de courbure

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6243522B1 (en) * 1998-12-21 2001-06-05 Corning Incorporated Photonic crystal fiber
WO2002039159A1 (fr) * 2000-11-10 2002-05-16 Crystal Fibre A/S Fibres optiques presentant des proprietes speciales de dispersion et de courbure

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10197727B2 (en) 2004-01-16 2019-02-05 Imra America, Inc. Large core holey fibers
WO2006099017A1 (fr) * 2005-03-11 2006-09-21 Massachusetts Institute Of Technology Fibre optique microstructuree a zone en mode large
US7787729B2 (en) 2005-05-20 2010-08-31 Imra America, Inc. Single mode propagation in fibers and rods with large leakage channels
US10067289B2 (en) 2005-05-20 2018-09-04 Imra America, Inc. Single mode propagation in fibers and rods with large leakage channels
US8755658B2 (en) 2007-02-15 2014-06-17 Institut National D'optique Archimedean-lattice microstructured optical fiber
US8995051B2 (en) 2007-09-26 2015-03-31 Imra America, Inc. Glass large-core optical fibers
US10353144B2 (en) 2007-09-26 2019-07-16 Imra America, Inc. Glass large-core optical fibers
US9632243B2 (en) 2007-09-26 2017-04-25 Imra America, Inc. Glass large-core optical fibers
JP2018527601A (ja) * 2015-06-25 2018-09-20 エヌケイティー フォトニクス アクティーゼルスカブＮｋｔ Ｐｈｏｔｏｎｉｃｓ Ａ／Ｓ 送達ファイバ・アセンブリおよび広帯域源
CN107710040A (zh) * 2015-06-25 2018-02-16 Nkt光子学有限公司 传输光纤组件和宽带光源
EP3314318A4 (fr) * 2015-06-25 2019-02-20 NKT Photonics A/S Ensemble fibres de distribution et source à large bande
WO2016206700A1 (fr) 2015-06-25 2016-12-29 Nkt Photonics A/S Ensemble fibres de distribution et source à large bande
US10649136B2 (en) 2015-06-25 2020-05-12 Nkt Photonics A/S Delivery fiber assembly and a broad band source
US11137541B2 (en) 2015-06-25 2021-10-05 Nkt Photonics A/S Delivery fiber assembly and a broad band source
US11703635B2 (en) 2015-06-25 2023-07-18 Nkt Photonics A/S Delivery fiber assembly and a broad band source
PL424807A1 (pl) * 2018-03-08 2019-09-09 Polskie Centrum Fotoniki I Światłowodów Światłowodowy czujnik zgięć oraz sposób pomiaru zgięć

Also Published As

Publication number Publication date
AU2003254639A1 (en) 2004-03-11

Similar Documents

Publication Publication Date Title
US7266275B2 (en) Nonlinear optical fibre method of its production and use thereof
US7174078B2 (en) Dual core photonic crystal fibers (PCF) with special dispersion properties
EP2585863B1 (fr) Fibre optique monomode à grande zone de c ur
US7590323B2 (en) Optical fibre with high numerical aperture, method of its production, and use thereof
EP1086391B1 (fr) Fibres optiques microstructurees
CA2445280C (fr) Fibre optique structuree avec region de gainage dimensionnee pour fournir une grande ouverture numerique, methode de production et utilisation connexes
US7349611B2 (en) Photonic bandgap fibre, and use thereof
US7366388B2 (en) Hollow-core optical fiber and method of making same
AU2002336075A1 (en) Optical fibre with high numerical aperture, method of its production, and use thereof
WO2015116849A1 (fr) Fibre à cœur arrondi filé
US20110141757A1 (en) All solid photonic bandgap fiber
EP3105623B1 (fr) Fibre optique microstructurée comportant des espaces sélectivement agrandis à indice de réfraction réduit
US7805038B2 (en) Birefringent photonic bandgap optical waveguide
Savović et al. Method for investigation of mode coupling in multimode step-index silica photonic crystal fibers
WO2004019092A1 (fr) Fibre en cristal photonique
WO2004053550A1 (fr) Ameliorations relatives a des fibres a cristaux photoniques
Mahnot et al. Photonic crystal fiber-an overview
EP1696251A2 (fr) Fibre optique avec grande ouverture numérique, procédé de production et son utilisation
Kliros et al. Prediction of macrobending and splice losses for photonic crystal fibers based on the effective index method
Cucinotta Photonic crystal fiber: Theory and fabrication
Broeng et al. Crystal fibre technology
Chen et al. Progress of photonic crystal fibers and their applications
Proulx et al. Design, fabrication, and characterization of holey fibers
Li et al. Nano-engineered optical fibers and applications
Bjarklev et al. Passive and active photonic crystal fibres

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NI NO NZ OM PG PH PL PT RO SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP

点击 这是indexloc提供的php浏览器服务，不要输入任何密码和下载