WO2017150699A1 - 光ファイバ、光システム及び光ファイバの製造方法 - Google Patents
光ファイバ、光システム及び光ファイバの製造方法 Download PDFInfo
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- WO2017150699A1 WO2017150699A1 PCT/JP2017/008451 JP2017008451W WO2017150699A1 WO 2017150699 A1 WO2017150699 A1 WO 2017150699A1 JP 2017008451 W JP2017008451 W JP 2017008451W WO 2017150699 A1 WO2017150699 A1 WO 2017150699A1
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- optical fiber
- support
- core
- layer
- tubular
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- 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
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
- C03B37/01211—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
- C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
- C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
- C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
- C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
- C03B37/02781—Hollow fibres, e.g. holey fibres
-
- 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
-
- 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
- G02B6/032—Optical fibres with cladding with or without a coating with non solid core or 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
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2203/00—Fibre product details, e.g. structure, shape
- C03B2203/10—Internal structure or shape details
- C03B2203/14—Non-solid, i.e. hollow products, e.g. hollow clad or with core-clad interface
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2203/00—Fibre product details, e.g. structure, shape
- C03B2203/10—Internal structure or shape details
- C03B2203/22—Radial profile of refractive index, composition or softening point
-
- 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
- G02B6/02328—Hollow or gas filled core
-
- 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
- G02B6/02333—Core having higher refractive index than cladding, e.g. solid core, effective index 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
- G02B6/02295—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
Definitions
- the present invention relates to an optical fiber having an air layer in a clad portion such as a Bragg type air core fiber or an air clad fiber, an optical system, and an optical fiber manufacturing method.
- Non-Patent Documents 1 and 2 an optical fiber having a tubular air layer in a clad portion so as to surround the core, such as a Bragg type air core fiber or an air clad fiber, is known (see Non-Patent Documents 1 and 2).
- the optical fiber manufacturing method described in Non-Patent Documents 1 and 2 includes forming a base material by alternately laminating a tubular member made of quartz glass and a large number of capillaries made of quartz glass. A stack and draw method of drawing is used.
- capillaries are packed between the tubular members without any gap in the circumferential direction of the optical fiber, and a large number are arranged in close contact.
- an air layer is formed by the arrangement of the capillaries, and at the same time, the contact portions of adjacent capillaries and a part of the tubular member sandwiching the capillaries melt, so that the wall-shaped support member becomes the longitudinal direction of the optical fiber. Formed along.
- Non-Patent Documents 1 and 2 a large number of support members corresponding to the capillaries are present in the air layer, and the thickness of the support members increases, which causes deterioration in transmission characteristics. It was.
- the present invention provides an optical fiber having an air layer in a clad part, an optical fiber capable of suppressing deterioration of transmission characteristics due to a support member existing in the air layer, an optical system, and an optical fiber manufacturing method. With the goal.
- One aspect of the present invention is an optical fiber including a core, a tubular layer that is concentrically disposed around the core via an air layer, and a support member that is disposed in the air layer and connects the core and the tubular layer.
- the support member interval between the support members in the circumferential direction of the optical fiber is wider than twice the thickness of the air layer in which the support member is disposed.
- the gist of the optical fiber is as follows.
- the optical fiber according to one aspect of the present invention is characterized in that the support member is composed of one support plate or two support plates paired in a wall shape.
- the optical fiber according to one aspect of the present invention is characterized in that the support member includes one support plate or two support plates that are paired in a wall shape with a member inner wall interval narrower than the support member interval.
- the optical fiber according to one aspect of the present invention is characterized in that the core is a hollow core inside a tubular core guide tube.
- the optical fiber according to one embodiment of the present invention is characterized in that a core is made of glass and a cladding layer that confines light is formed by an air layer and a tubular layer disposed through the air layer.
- the optical fiber according to one aspect of the present invention is characterized in that the core is made of glass, and the core includes a portion having a refractive index different from that of the core.
- the optical fiber according to one embodiment of the present invention is characterized in that the tubular layer is quartz glass or quartz glass doped with a dopant.
- the support members are arranged apart from each other along the circumferential direction of the optical fiber, and the support member spacing between the different support members in the circumferential direction of the optical fiber is the thickness of the corresponding air layer. It is characterized by being wider than twice.
- the optical fiber according to one embodiment of the present invention is characterized in that the support member and the tubular layer have the same viscosity.
- the support member and the tubular layer are made of the same material.
- the thickness of the supporting plate or the two supporting plates paired in a wall shape in the circumferential direction of the supporting plate is transmitted through the core.
- the mode is characterized in that the mode cannot be localized.
- the thickness of the support plate or the two support plates paired in a wall shape in the circumferential direction of the support plate is that of the light transmitted through the core. It is characterized by being thinner than the wavelength.
- the tubular layer is periodically arranged in a plurality of concentric layers with a plurality of air layers interposed therebetween, and a support member is arranged in each of the plurality of air layers, and at least one or more In the air layer, the support member interval is wider than twice the thickness of the corresponding air layer.
- the optical fiber according to one aspect of the present invention is characterized in that the support members arranged in each of the plurality of air layers are arranged in a straight line along the same radial direction.
- the optical fiber according to one aspect of the present invention is characterized in that the support member is disposed so as to include each position of a plurality of air layers in different radial directions.
- the optical fiber according to one embodiment of the present invention is characterized in that the number of support members is different for each of a plurality of air layers.
- the number of support members disposed in the air layer close to the center side is smaller than the number of support members disposed in the air layer close to the outer peripheral side, and is supported in all air layers.
- the member interval is wider than twice the thickness of the corresponding air layer.
- Another aspect of the present invention is an optical system characterized by using the optical fiber according to one aspect of the present invention.
- Still another embodiment of the present invention includes a step of concentrically arranging a tubular tubular base material layer with an air layer sandwiched around the core base material portion, and a space between the core base material portion and the tubular layer base material layer.
- An optical fiber manufacturing method including a step of melting and drawing a fiber preform so that a portion is a support member, and the support members in the circumferential direction of the optical fiber in a longitudinal sectional view of the optical fiber
- the gist of the optical fiber manufacturing method is that the spacing between the supporting members is wider than twice the thickness of the air layer in which the supporting members are disposed.
- the support base material portion is a capillary
- the drawing step includes drawing the walls of the capillary so as to form a pair of support plates.
- an optical fiber having an air layer in a clad part, an optical fiber capable of suppressing deterioration of transmission characteristics due to a support member existing in the air layer, an optical system, and an optical fiber manufacturing method. can do.
- FIG. 1 is a cross-sectional view perpendicular to the longitudinal direction showing an example of an optical fiber according to the first embodiment of the present invention.
- FIG. 2 is a partially enlarged view of FIG.
- FIG. 3 is an end view seen from the longitudinal direction of the preform for manufacturing the optical fiber according to the first embodiment of the present invention.
- FIG. 4A is a plan view of an upper plate for manufacturing an optical fiber according to the first embodiment of the present invention
- FIG. 4B is a diagram of light according to the first embodiment of the present invention. It is a top view of the baseplate for manufacturing a fiber.
- FIG. 5A and FIG. 5B are schematic views showing a state in which a base material for manufacturing the optical fiber according to the first embodiment of the present invention is manufactured.
- FIG. 6 is a cross-sectional view perpendicular to the longitudinal direction of a base material into which a capillary for manufacturing an optical fiber according to the first embodiment of the present invention is inserted.
- FIG. 7A and FIG. 7B are cross-sectional views perpendicular to the longitudinal direction showing an example of an optical fiber according to a first modification of the first embodiment of the present invention.
- FIGS. 8A and 8B are cross-sectional views perpendicular to the longitudinal direction showing an example of an optical fiber according to a first modification of the first embodiment of the present invention.
- FIG. 9A and FIG. 9B are cross-sectional views perpendicular to the longitudinal direction showing an example of an optical fiber according to a first modification of the first embodiment of the present invention.
- FIG. 10B are cross-sectional views perpendicular to the longitudinal direction showing an example of an optical fiber according to a second modification of the first embodiment of the present invention.
- FIG. 11A is a cross-sectional view perpendicular to the longitudinal direction showing an example of an optical fiber according to a third modification of the first embodiment of the present invention, and
- FIG. It is sectional drawing perpendicular
- FIG. 12A and FIG. 12B are cross-sectional views perpendicular to the longitudinal direction showing an example of an optical fiber according to a fifth modification of the first embodiment of the present invention.
- FIG. 13 is a cross-sectional view perpendicular to the longitudinal direction showing an example of an optical fiber according to the second embodiment of the present invention.
- FIG. 14 is a plan view of an upper plate for manufacturing an optical fiber according to the second embodiment of the present invention.
- FIG. 15 is a cross-sectional view perpendicular to the longitudinal direction of a base material into which a capillary for manufacturing an optical fiber according to the second embodiment of the present invention is inserted.
- FIGS. 16A and 16B are cross-sectional views perpendicular to the longitudinal direction showing an example of an optical fiber according to a first modification of the second embodiment of the present invention.
- FIGS. 17A and 17B are cross-sectional views perpendicular to the longitudinal direction showing an example of an optical fiber according to a second modification of the second embodiment of the present invention.
- FIG. 18A is a cross-sectional view perpendicular to the longitudinal direction showing an example of an optical fiber according to a third modification of the second embodiment of the present invention, and
- FIG. It is sectional drawing perpendicular
- FIGS. 19A and 19B are cross-sectional views perpendicular to the longitudinal direction showing an example of an optical fiber according to a fifth modification of the second embodiment of the present invention.
- FIG. 20 (a) is a cross-sectional view perpendicular to the longitudinal direction showing a hole core fiber according to an example of the second embodiment of the present invention
- FIG. 20 (b) is shown in FIG. 20 (a).
- the light intensity distribution of a hollow core fiber is shown.
- FIG. 21 is a graph showing a simulation result of confinement loss when the thickness of the support plate is changed in the four-layered hole core fiber according to the example of the second embodiment of the present invention.
- FIG. 22 is a graph showing a simulation result of confinement loss when the thickness of the support plate is changed in the five-layered hole core fiber according to the example of the second embodiment of the present invention.
- FIG. 23 is a cross-sectional view perpendicular to the longitudinal direction showing an example of an optical fiber according to another embodiment of the present invention.
- FIG. 24 is a cross-sectional view perpendicular to the longitudinal direction showing another example of an optical fiber according to another embodiment of the present invention.
- FIG. 25 is a cross-sectional view perpendicular to the longitudinal direction showing still another example of an optical fiber according to another embodiment of the present invention.
- FIG. 26 is a cross-sectional view perpendicular to the longitudinal direction showing still another example of an optical fiber according to another embodiment of the present invention.
- FIG. 27 is a schematic graph related to an optical fiber design that selectively propagates light of a desired wavelength according to another embodiment of the present invention.
- FIG. 28 (a) is a schematic diagram showing an example of high power application of a hole-clad fiber according to another embodiment of the present invention
- FIG. 28 (b) is a diagram showing an empty space according to another embodiment of the present invention. It is the schematic which shows an example of the high power application of a hole core fiber.
- FIG. 29 is a cross-sectional view perpendicular to the longitudinal direction showing an optical fiber according to a first comparative example.
- FIG. 30 is a partially enlarged view of FIG.
- FIG. 31 is a cross-sectional view perpendicular to the longitudinal direction showing an optical fiber according to a second comparative example.
- first and second embodiments described below exemplify an optical fiber and a manufacturing method thereof for embodying the technical idea of the present invention, and the technical idea of the present invention is configured as follows.
- the material of the parts, their shape, structure, arrangement, etc. are not specified below.
- the technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.
- the optical fiber according to the first embodiment of the present invention defines a core (hole core) 1 inside, and a tubular core guide tube 21 extending in the longitudinal direction of the optical fiber;
- a Bragg type air core comprising a multilayer clad portion 2 arranged in multiple layers so as to form a periodic structure with a plurality of air layers (air clads) sandwiched around the core guide tube 21 and extending in the longitudinal direction of the optical fiber. It is a fiber.
- the multilayer clad part 2 has a Bragg-type reflection structure including tubular layers 22 to 25 made of a plurality of dielectrics periodically arranged concentrically with air layers alternately sandwiched around the core guide tube 21. .
- An air layer is defined between the core guide tube 21 and the tubular layer 22, between the tubular layer 22 and the tubular layer 23, between the tubular layer 23 and the tubular layer 24, and between the tubular layer 24 and the tubular layer 25.
- the distance between the core guide tube 21 and the tubular layer 22, the distance between the tubular layer 22 and the tubular layer 23, the distance between the tubular layer 23 and the tubular layer 24, and the distance between the tubular layer 24 and the tubular layer 25 are transmitted through the core 1 of the optical fiber. It is determined in consideration of the conditions of Bragg reflection (Bragg diffraction) with respect to the wavelength of the light to be emitted.
- the material of the core guide tube 21 and the tubular layers 22 to 25 for example, a dielectric such as quartz glass (silica glass) or quartz glass doped with a dopant can be used.
- the core guide tube 21 and the tubular layers 22 to 25 may be made of the same material, and may be made of different materials as long as an optically Bragg-type periodic structure can be realized.
- support members 3a to 3l are provided in the air layers between the core guide tube 21 and the tubular layers 22 to 25 along the longitudinal direction of the optical fiber. Yes. That is, in the air layer between the core guide tube 21 and the tubular layer 22, a plurality of support members 3 a, 3 e, 3 i are provided so as to connect the core guide tube 21 and the tubular layer 22. In the air layer between the tubular layer 22 and the tubular layer 23, a plurality of support members 3 b, 3 f, 3 j are provided so as to connect the tubular layer 22 and the tubular layer 23.
- a plurality of support members 3 c, 3 g, 3 k are provided so as to connect the tubular layer 23 and the tubular layer 24.
- a plurality of support members 3 d, 3 h, and 3 l are provided so as to connect the tubular layer 24 and the tubular layer 25.
- the support member 3a is composed of two support plates (support walls) 31a and 31b that extend in parallel with each other along the longitudinal direction of the optical fiber in a wall-like (plate-like) pair.
- the member inner wall spacing S0 defined inside the support plate 31a and the support plate 31b that make a pair with each other is approximately the same as the thickness G1 of the air layer between the core guide tube 21 and the tubular layer 22, and at least the core guide tube The spacing is narrower than twice the thickness G1 of the air layer between 21 and the tubular layer 22.
- the support member 3b includes two support plates 32a and 32b extending in parallel to each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the distance between the inner wall surfaces of the pair of support plates 32a and 32b is approximately the same as the thickness of the air layer between the tubular layer 22 and the tubular layer 23, and at least the thickness of the air layer between the tubular layer 22 and the tubular layer 23. It is an interval narrower than twice.
- the support member 3c includes two support plates 33a and 33b extending in parallel with each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the distance between the inner wall surfaces of the pair of supporting plates 33a and 33b is approximately the same as the thickness of the air layer between the tubular layer 23 and the tubular layer 24, and at least the thickness of the air layer between the tubular layer 23 and the tubular layer 24. It is an interval narrower than twice.
- the support member 3d is composed of two support plates 34a and 34b extending in parallel with each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the distance between the inner wall surfaces of the pair of support plates 34a and 34b is equal to the thickness of the air layer between the tubular layer 24 and the tubular layer 25, and at least the thickness of the air layer between the tubular layer 24 and the tubular layer 25. It is an interval narrower than twice.
- the support member 3e is composed of two support plates 31c and 31d extending in parallel to each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the space between the inner walls of the supporting plates 31c and 31d forming a pair is approximately the same as the thickness G1 of the air layer between the core guide tube 21 and the tubular layer 22, and at least the air between the core guide tube 21 and the tubular layer 22 The spacing is narrower than twice the layer thickness G1.
- the support member 3f includes two support plates 32c and 32d extending in parallel to each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the space between the inner walls of the pair of supporting plates 32c and 32d is approximately the same as the thickness of the air layer between the tubular layer 22 and the tubular layer 23, and at least the thickness of the air layer between the tubular layer 22 and the tubular layer 23. It is an interval narrower than twice.
- the support member 3g is composed of two support plates 33c and 33d extending in parallel with each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the distance between the inner walls of the members of the pair of support plates 33c and 33d is about the same as the thickness of the air layer, and is at least narrower than twice the thickness of the air layer.
- the support member 3h is composed of two support plates 34c and 34d extending in parallel with each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the distance between the inner walls of the members of the pair of support plates 34c and 34d is about the same as the thickness of the air layer, and is at least narrower than twice the thickness of the air layer.
- the support member 3i is composed of two support plates 31e and 31f extending in parallel with each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the member inner wall spacing between the pair of support plates 31e, 31f is approximately the same as the thickness G1 of the air layer between the core guide tube 21 and the tubular layer 22, and at least the air between the core guide tube 21 and the tubular layer 22 The spacing is narrower than twice the layer thickness G1.
- the support member 3j is composed of two support plates 32e and 32f extending in parallel to each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the space between the inner walls of the pair of support plates 32e and 32f is the same as the thickness of the air layer between the tubular layer 22 and the tubular layer 23, and at least the thickness of the air layer between the tubular layer 22 and the tubular layer 23. It is an interval narrower than twice.
- the support member 3k is composed of two support plates 33e and 33f extending in parallel with each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the space between the inner walls of the pair of support plates 33e and 33f is approximately the same as the thickness of the air layer between the tubular layer 23 and the tubular layer 24, and at least the thickness of the air layer between the tubular layer 23 and the tubular layer 24. It is an interval narrower than twice.
- the support member 3l is composed of two support plates 34e and 34f extending in parallel with each other along the longitudinal direction of the optical fiber in a wall-like pair.
- the space between the inner walls of the pair of support plates 34e and 34f is approximately the same as the thickness of the air layer between the tubular layer 24 and the tubular layer 25, and at least the thickness of the air layer between the tubular layer 24 and the tubular layer 25. It is an interval narrower than twice.
- each of the support members 3a to 3l includes, for example, two wall-like support plates 31a. 31b: 31c, 31d; 31e, 31f; 32a. 32b: 32c, 32d; 32e, 32f; 33a. 33b: 33c, 33d; 33e, 33f; 34a. 34b: 34c, 34d; 34e, 34f can be formed.
- the support member 3a is formed of a capillary, as shown in FIG. 2, a pair (set) of a member inner wall interval S0 in which the wall-shaped support plate 31a and the support plate 31b are separated by an order of the diameter of the capillary is formed.
- the member inner wall spacing S0 is approximately the same as the thickness G1 of the air layer.
- the other support members 3b to 3l shown in FIG. 1 have the same structure as that of the support member 3a shown in FIG. Therefore, if the same capillary is used to form the support members 3a to 3l, pairs of support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f that are separated by a common member inner wall interval are formed. Will be.
- the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f of the support members 3a to 3l have a plate shape (strip shape) close to an elongated rectangular shape (bar shape) in a cross-sectional view perpendicular to the longitudinal direction of the optical fiber. It is the shape.
- a plate shape strip shape
- bar shape elongated rectangular shape
- the support plates 31a to 31f, 32a to 32f, 33a to 33f, 34a to 34f are made of cylindrical capillaries, and the support plates 31a to 31f, 32a to 32f, 33a to 33f, 34a to
- 34f has a shape that bends outward of the pair is schematically illustrated, but the cross-sectional shapes perpendicular to the longitudinal direction of the optical fiber of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f Is not limited to this.
- the cross-sectional shapes perpendicular to the longitudinal direction of the optical fibers of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f may be substantially linear, for example, and can be controlled as appropriate according to the type of capillary, etc. It is.
- the material of the support members 3a to 3l glass such as quartz glass, polymer, or the like can be used.
- the support members 3a to 3l are preferably made of the same material as the core guide tube 21 and the tubular layers 22 to 25.
- the viscosity of the material constituting the support members 3a to 3l is preferably the same as the viscosity of the material constituting the core guide tube 21 and the tubular layers 22 to 25. That is, if the materials of the support members 3a to 3l, the core guide tube 21 and the tubular layers 22 to 25, or the viscosity characteristics of these materials are the same, the support members 3a to 3l, the core guide tube 21 and the tubular layers 22 to 25 are used.
- the support members 3a to 3l may be made of a material different from that of the core guide tube 21 and the tubular layers 22 to 25. Further, the support members 3a to 3l may be made of different materials.
- the support member interval (external interval) between the support members 3a to 3l in the circumferential direction of the optical fiber is the thickness of the air layer in which the support members 3a to 3l are arranged. It is wider than twice.
- the distance between the support members is the distance between the support members defined along the circumferential direction of the optical fiber between the support members 3a to 3l.
- the support member interval (external spacing) S1 in the circumferential direction of the optical fiber between the support member 3a and the support member 3e that is spaced from the support member 3a in the clockwise direction by about 120 ° in the circumferential direction is
- the thickness (air gap) G1 of the air layer between the core guide tube 21 and the tubular layer 22 sandwiching the support member 3a is wider than twice.
- the support member interval (external spacing) S2 in the circumferential direction of the optical fiber between the support member 3a and the support member 3i that is spaced from the support member 3a counterclockwise by about 120 ° in the circumferential direction sandwiches the support member 3a.
- the interval between the support plates 34a, 34b (member inner wall interval) S0 forming a pair of the support members 3a is the support between the support members 3a, 3e, 3i. It is narrower than the member spacing S1, S2.
- the intra space (member inner wall interval) S0 defined within the pair that is the side where the support plates 34a and 34b forming the pair of the support member 3a are close to each other is the side where the support plates 34a and 34b are close to each other. Is outside and on the opposite side, and is narrower than the mutual space (support member spacing) S1, S2 between the support members defined along the circumferential direction of the optical fiber.
- the intra space (member inner wall interval) S0 in the support member 3a is a distance narrower than twice the thickness (air gap) G1 of the air layer.
- the member inner wall spacing S0 is defined as the distance between the support plate 34a and the support plate 34b that are mirror images of each other.
- the thickness of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f of the support members 3a to 3l in the circumferential direction of the optical fiber (circumferential direction with the center of the core 1 being the center of the circle) It is preferable to set the thickness so that the mode of light transmitted through 1 cannot be localized.
- the plate thickness (wall thickness) of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f in the circumferential direction of the optical fiber depends on the wavelength of light transmitted through the core 1, for example, When the wavelength of light to be used is 1 ⁇ m, the thicknesses of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f in the circumferential direction of the optical fiber are set to be less than 1 ⁇ m, which is shorter than the wavelength. It is preferable.
- the mode corresponding to the wavelength of the light transmitted through the core 1 is set according to the thickness of the support plates 31a to 31f, 32a to 32f, 33a to 33f, 34a to 34f of the support members 3a to 3l in the circumferential direction of the optical fiber.
- the thickness of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f should be made thinner than the wavelength of light transmitted through the core 1, for example. Thus, leakage of light to the outside through the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f can be prevented, and loss of light transmitted through the core 1 can be suppressed.
- FIG. 1 the case where three support members 3a to 3l are arranged in each air layer constituting the multilayer clad part 2 is illustrated, but the support distributed to the air layers existing at different radial positions is illustrated.
- the number of members is not particularly limited.
- the number of support members arranged in each air layer is preferably as small as possible from the viewpoint of transmission characteristics, but is preferably 3 or more from the viewpoint of mechanical strength and stability of the structure.
- 1 illustrates the case where the support members 3a to 3l are spaced apart at equal intervals of about 120 °, the support members 3a to 3l may be disposed at different support member intervals. .
- the supporting members 3a to 3d arranged in the air layers at different radial positions constituting the multilayer clad part 2 are arranged on a straight line along the same radial direction.
- the support members 3e to 3h arranged in the air layers at different radial positions are arranged on a straight line along the same radial direction.
- the support members 3i to 3l arranged in the air layers at different radial positions are arranged on a straight line along the same radial direction.
- the support members 3a to 3d, the support members 3e to 3h, and the support members 3e to 3h arranged in the air layers at different radial positions are arranged to include the positions of the plurality of air layers in different radial directions. May be.
- the optical fibers according to the first and second comparative examples will be described.
- the optical fiber according to the first comparative example includes a tubular core guide tube 121 that defines a core (hole core) 101 inside, and a multilayer clad disposed around the core guide tube 121.
- An air-core fiber including a portion 102.
- the multilayer clad portion 102 includes a plurality of tubular layers 122 to 124 that sandwich an air layer.
- a plurality of wall-like support plates 131, 132, and 133 are arranged in the longitudinal direction of the optical fiber.
- the support plates 131, 132, and 133 are arranged at equal intervals along the circumferential direction of the optical fiber, the thicknesses of the support plates 131, 132, and 133 are shown in FIG.
- the features of the optical fiber according to the first embodiment of the present invention shown in FIG. 2 are that the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f shown in FIG. Different.
- the core guide tube 121, the tubular members constituting the tubular layers 122, 123, and 124 and the plurality of support plates 131, 132, and 133 are constructed by the stack and draw method.
- a large number of capillaries are sequentially stacked.
- a large number of capillaries are arranged between the tubular members without gaps in the circumferential direction of the optical fiber.
- the contact portions of adjacent capillaries and a part of the tubular member sandwiching the capillaries are coupled during fiber drawing, and a large number of support plates 131, 132, 133 having the same number as the capillaries are formed at equal intervals. Is done.
- the support member spacing S5 in the circumferential direction of the optical fiber between the support plates 131, 132, 133 formed from a large number of capillaries is about the same as the thickness G3 of the air layer in which the support plates 131, 132, 133 are disposed, and is at least narrower than twice the thickness G3, and is caused by the large number of support plates 131, 132, 133. As a result, transmission characteristics deteriorate.
- the thickness of the optical fiber support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f of the optical fiber according to the first embodiment of the present invention is doubled. It becomes thickness. If the wavelength of light is taken into account, light leakage through the large number of support plates 131, 132, and 133 is likely to occur, and the variation in effective dielectric constant increases, resulting in deterioration of transmission characteristics.
- the optical fiber according to the second comparative example is an air clad fiber including a solid core 101x and a tubular layer 102x arranged around the core 101x.
- the first point of the present invention shown in FIG. 2 is that a large number (for example, 48) of support plates 131 are arranged at equal intervals along the circumferential direction of the optical fiber between the core 101x and the tubular layer 102x. This is different from the characteristics of the optical fiber according to the embodiment.
- the manufacturing method of the optical fiber according to the second comparative example is the same as the manufacturing method of the optical fiber according to the first comparative example. Therefore, also in the optical fiber according to the second comparative example, the support member interval S5 in the circumferential direction of the optical fibers between the support plates 131 is approximately the same as the thickness G3 of the air layer in which the support plates 131 are disposed. Thus, the thickness is narrower than at least twice the thickness G3, and transmission characteristics deteriorate due to the large number of support plates 131. Further, the thickness of the large number of support plates 131 is twice the thickness of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f of the optical fiber according to the first embodiment of the present invention. . The increase in the thickness of the plate is about twice as much, since the light leakage through the large number of support plates 131 is likely to occur and the variation in effective dielectric constant is increased in consideration of the wavelength of light. The transmission characteristics are deteriorated.
- the supporting members 3a to 3l are separated from each other, and the circumferential direction of the optical fiber between the supporting members 3a to 3l
- the support member interval is made wider than twice the thickness of the air layer in which the support members 3a to 3l are arranged.
- the number of support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f of the support members 3a to 3l can be reduced.
- the thickness and shape of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f of the support members 3a to 3l have a great influence on the characteristics. For this reason, it is important to control the structure of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f by making the plate thickness thin or linear.
- the contact portions of adjacent capillaries are not drawn during fiber drawing. Combine to form a single support plate. For this reason, in addition to the double plate thickness, structural distortion and the like are likely to occur, and it is difficult to control the thickness and shape of the support plate.
- the distance between the support members 3a to 3l in the circumferential direction of the optical fiber is set to the air in which the support members 3a to 3l are arranged.
- a pair of support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f are individually formed from one capillary by making the thickness larger than twice the thickness of the layer. Therefore, the plate thickness and shape of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f can be easily controlled, as well as the thin plate thickness can be easily realized as compared with the first and second comparative examples. Become.
- optical fiber manufacturing method Next, an example of an optical fiber manufacturing method according to the first embodiment of the present invention will be described with reference to FIGS.
- the manufacturing method of the optical fiber described below is an example, and as long as it is the range of the meaning described in the claim, it cannot be overemphasized by various manufacturing methods other than this.
- a tubular core base material portion 41 made of quartz or the like having pores of appropriate dimensions and a plurality of tubular layer base material layers 42 to 45 are concentrically arranged and cycled. Are spaced apart. Then, the ends of the core base material portion 41 and the tubular layer base material layers 42 to 45 are temporarily fixed with the tape 8 to maintain the air gap between the core base material portion 41 and the tubular layer base material layers 42 to 45. . Note that an adhesive or the like may be used instead of the tape 8.
- FIG. 4A An upper plate (round plate) 5 made of quartz glass or the like as shown in FIG. Openings (holes) 51a to 51c, 52a to 52c, 53a to 53c, and 54a to 54c are cut out on the upper plate 5 using drills or the like at positions where a plurality of capillaries are passed. Further, a bottom plate (round plate) 6 facing the upper plate 5 as shown in FIG. 4B is prepared separately. The bottom plate 6 may also be provided with openings corresponding to the openings 51a to 51c, 52a to 52c, 53a to 53c, and 54a to 54c of the upper plate 5. Then, as shown in FIG. 5A, the temporarily fixed core base material portion 41 and one end of the plurality of tubular layer base material layers 42 to 45 are combined with the bottom plate 6 and temporarily fixed by heating or the like.
- FIG. 5B a plurality (12) of openings (holes) 51a to 51c, 52a to 52c, 53a to 53c, and 54a to 54c of the upper plate 5 are provided.
- capillaries (support base materials) 61a to 61d, 62a to 62d, 63a to 63d (capillary 62a to 62d and 63a to 63d are not shown in FIG. 5B, see FIG. 6), capillaries 61a to 61d and 62a To 62d and 63a to 63d are inserted while being aligned between the core base material portion 41 and the plurality of tubular layer base material layers 42 to 45.
- the capillaries 61a to 61d, 62a to 62d, 63a to 63d are fused and connected to the inner surface or the outer surface of the core base material portion 41 and the plurality of tubular layer base material layers 42 to 45 by heat.
- a plurality of capillaries 61a to 61d, 62a to 62d, and 63a to 63d are disposed in the circumferential direction between the core base material portion 41 and the tubular layer base material layers 42 to 45.
- a fiber preform 4 that is integrated and fixed so as to be separated is obtained.
- a drawing process for heating and drawing the fiber preform 4 is performed.
- the fiber preform 4 is melted and drawn so that the core preform 41 is the core guide tube 21 and the tubular layer preforms 42 to 45 are the tubular layers 22 to 25.
- the core is a solid core made of glass or the like, a cylindrical core base material portion for forming the core is prepared, and the core is drawn so that the cylindrical core base material portion serves as the core.
- the capillaries 61 a, 62 a, 63 a are deformed, and a part of the outer surface of the core preform 41 sandwiching the capillaries 61 a, 62 a, 63 a and the inner surface of the tubular layer preform 42.
- the capillaries 61a, 62a, 63a are also drawn and thinned.
- the walls of the capillaries 61a, 62a, and 63a are supported by the support plates 31a and 31b that form a pair with the support member 3a, the support plates 31c and 31d that form a pair with the support member 3e, and the support member 3i that form a pair with each other. It is drawn so that it may become board 31e, 31f.
- the support member intervals S1 and S2 between the support members 3a, 3e, and 3i in the circumferential direction of the optical fiber are defined as an air layer in which the support member 3a is disposed.
- the thickness (air gap) is larger than twice the thickness G1.
- the capillaries 61b, 62b, and 63b are deformed and the molten state with the tubular base material layers 42 and 43 proceeds, so that the walls of the capillaries 61b, 62b, and 63b are respectively connected to the support members 3b, 3f, and 3j.
- the support plates 32a to 32f that are paired with each other are drawn.
- the capillaries 61c, 62c, 63c are deformed and the molten state with the tubular base material layers 43, 44 advances, so that the walls of the capillaries 61c, 62c, 63c are mutually connected to the support members 3c, 3g, 3k.
- the support plates 33a to 33f forming a pair are drawn.
- the capillaries 61d, 62d, and 63d are deformed and the molten state with the tubular layer base material layers 44 and 45 advances, so that the walls of the capillaries 61d, 62d, and 63d are respectively connected to the support members 3d, 3h, and 3l.
- the support plates 34a to 34f forming a pair are drawn. In this way, the optical fiber shown in FIG. 1 is completed.
- the capillaries 61a to 61d, 62a to 62d, and 63a to 63d are cylindrical is illustrated, it is not particularly limited thereto.
- the hole shapes and outer shapes of the capillaries 61a to 61d, 62a to 62d, and 63a to 63d may be elliptical, polygonal such as square or hexagonal.
- the number of capillaries 61a to 61d, 62a to 62d, 63a to 63d is not limited.
- a plurality of capillaries (support base material portions) 61a to 61d, 62a to 62d, and 63a to 63d are arranged spaced apart in the circumferential direction.
- the support members 3a to 3l are formed so that the support member spacing between the support members 3a to 3l in the circumferential direction of the optical fiber is larger than twice the thickness of the air layer in which the support members 3a to 3l are disposed. To do. Thereby, the number of support members 3a to 3l can be reduced as compared with the first and second comparative examples, and an optical fiber capable of suppressing the deterioration of transmission characteristics due to the support members 3a to 3l can be realized.
- a pair of wall-like support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f that form mirror images are individually formed from one capillary. Therefore, since the thickness of the support plates 31a to 31f, 32a to 32f, 33a to 33f, and 34a to 34f can be made thinner than those of the first and second comparative examples, the support plates 31a to 31f and 32a to 32f can be reduced. , 33a to 33f, and 34a to 34f, light leakage can be reduced.
- the support member 3a, the support member 3b, the support member 3c, and the support member 3d may be arrange
- the support member interval S1 between the support members 3a in the circumferential direction of the optical fiber, that is, the side surfaces of the support member 3a is 2 of the thickness G1 of the air layer in which the support member 3a is disposed. Wide than twice.
- two support members 3a and 3e, support members 3b and 3f, support members 3c and 3g, and support members 3d and 3h are arranged from the inner air layer, two in each air layer. May be.
- the support member intervals S1 and S2 between the support members 3a and 3b in the circumferential direction of the optical fiber are wider than twice the thickness G1 of the air layer in which the support member 3a is disposed. .
- the support member 3m is composed of support plates 31g and 31h forming a wall-like pair.
- the support member 3n includes support plates 32g and 32h forming a wall-like pair.
- the support member 3o includes support plates 33g and 33h forming a wall-like pair.
- the support member 3p is composed of support plates 34g and 34h that form a wall-like pair.
- support members 3a, 3e, 3i, 3m, 3q, 3u, support members 3b, 3f, 3j, 3n, 3r, 3v, and support members are provided for each air layer.
- 3c, 3g, 3k, 3o, 3t, 3w and support members 3d, 3h, 3l, 3p, 3t, 3x may be arranged.
- the support member 3q includes support plates 31i and 31j that form a wall-like pair.
- the support member 3r includes support plates 32i and 32j that form a wall-like pair.
- the support member 3s includes support plates 33i and 33j that form a wall-like pair.
- the support member 3t includes support plates 34i and 34j that form a wall-like pair.
- the support member 3u includes support plates 31k and 31l that form a wall-like pair.
- the support member 3v includes support plates 32k and 32l that form a wall-like pair.
- the support member 3w includes support plates 33k and 33l forming a wall-like pair.
- the support member 3x is composed of support plates 34k and 34l that form a wall-like pair.
- FIG. 9 (a) eight support members 3a to 3d may be arranged in each air layer, in addition to support members 3a to 3d.
- FIG. 9A focusing on the support member 3a disposed in the innermost air layer, the support member intervals (external intervals) S1 and S2 of the support member 3a in the circumferential direction of the optical fiber are arranged in the support member 3a.
- the thickness of the air layer (air gap) G1 is about twice as large as the gap G1, but the support member spacing (outer spacing) S1, S2 is wider than the member inner wall spacing S0 of the support member 3a.
- the support member intervals (external intervals) S3 and S4 of the support member 3d in the circumferential direction of the optical fiber are the air layers in which the support member 3d is arranged. It is wider than twice the thickness (air gap) G2.
- S3 and S4 are wider than twice the thickness (air gap) G2 of the air layer in which the support member 3d is disposed, and the external intervals S1 and S2 are narrower than twice the thickness G1 of the air layer.
- the outer spacing S1, S2 is wider than the member inner wall spacing S0.
- the proximity of the support members arranged in the most disadvantageous air layer, for example, the innermost air layer is not achieved, the proximity of the support members arranged in the most disadvantageous air layer, for example, the innermost air layer, It is sufficient that the member inner wall interval defined on the side to be closed is narrower than the outer interval defined on the side opposite to the side adjacent to the support members disposed in the innermost air layer.
- the support member intervals S1 and S2 of the support member 3a in the circumferential direction of the optical fiber are the air in which the support member 3a is disposed. It is about the same as the layer thickness (air gap) G1.
- the support member intervals S3 and S4 of the support member 3d in the circumferential direction of the optical fiber are 2 of the air layer thickness (air gap) G2 where the support member 3d is disposed. Wide than twice.
- the number of support members arranged in each air layer may be other than the number described here.
- the support members disposed in the air layers may be disposed including the positions of the air layers in different radial directions.
- the support members 3a and 3e, support members 3b and 3f, support members 3c and 3g, and support members 3d and 3h are arranged in each air layer.
- the support members 3a to 3d are arranged so as to be shifted along different radial directions.
- the support members 3e to 3h are arranged so as to be shifted along different radial directions.
- Support members 3a and 3c are intermittently arranged along the same radial direction.
- the support members 3b and 3d are at positions shifted by 90 ° from the support members 3a and 3c, and are intermittently disposed along the same radial direction.
- the support members 3e and 3g are positions shifted by 90 ° from the support members 3b and 3d, and are intermittently disposed along the same radial direction.
- the support members 3f and 3h are positions shifted by 90 ° from the support members 3e and 3g, and are intermittently disposed along the same radial direction.
- the number of support members may be different for each air layer having a different radial position.
- the number of the support members 3a, 3b, 3c, 3d, 3f, 3g, 3h, 3k, 3l, and 3p may be larger in the outer air layer along the radial direction.
- one support member 3a is disposed in the innermost air layer along the radial direction.
- Two support members 3b and 3f are arranged in the second air layer from the inside.
- Three support members 3c, 3g, and 3k are arranged in the third air layer from the inside.
- Four support members 3d, 3h, 3l and 3p are arranged in the outermost air layer.
- the number of support members arranged in each air layer is the same, the closer the air layer is to the center side, the narrower the support member interval, which is the interval between the support members, and the corresponding air layer thickness. It may be narrower than twice.
- the number of support members arranged in each air layer is made different so that the support members are arranged in the air layer close to the center side. By reducing the number of support members less than the number of support members arranged in the air layer close to the outer peripheral side, the support member spacing in all air layers is made wider than twice the thickness of the corresponding air layer. Also good.
- support members may be arranged at different support member intervals in the circumferential direction of the optical fiber.
- three support members 3a to 3d, support members 3e to 3h, and support members 3i to 3l are arranged along the same radial direction in each air layer.
- the support member spacing S1 between the support member 3a and the support member 3e in the circumferential direction of the optical fiber is the support member along the circumferential direction of the optical fiber of the support member 3a and the support member 3i. It is wider than the interval S2.
- an optical fiber according to a fifth modification of the first embodiment of the present invention includes a core 1x having a solid structure made of glass or the like, and an air layer around the core 1x. 1 is different from the configuration of the air-core fiber that is an optical fiber according to the first embodiment of the present invention shown in FIG. 1 in that the air-clad fiber (holey fiber) includes the tubular layer 2x disposed through the optical fiber.
- a clad layer for confining light is constituted by the air layer and the tubular layer 2x.
- a plurality of support plates 31a to 31f are arranged in the air layer between the core 1x and the tubular layer 2x. Also in the air-clad fiber according to the fifth modification, the number of the plurality of support plates 31a to 31f can be reduced as compared with the air-clad fiber according to the comparative example shown in FIG. Can be suppressed.
- an air clad fiber having a plurality of tubular layers 22 to 25 arranged concentrically around the core 1x may be used.
- the air clad fiber shown in FIG. 12B is different from the structure of the air core fiber shown in FIG. 1 in that the core 1x has a solid structure.
- the optical fiber according to the second embodiment of the present invention defines a core (hole core) 1 on the inside, and a tubular core guide tube 21 extending in the longitudinal direction of the optical fiber;
- a Bragg type air core comprising a multilayer clad portion 2 arranged in multiple layers so as to form a periodic structure with a plurality of air layers (air clads) sandwiched around the core guide tube 21 and extending in the longitudinal direction of the optical fiber. It is a fiber.
- the multilayer clad part 2 has a Bragg-type reflection structure including tubular layers 22 to 25 made of a plurality of dielectrics periodically arranged around the core guide tube 21 with air layers alternately interposed therebetween.
- An air layer is defined between the core guide tube 21 and the tubular layer 22, between the tubular layers 22 and 23, between the tubular layers 23 and 24, and between the tubular layers 24 and 25, thereby forming a periodic structure. .
- the distance between the core guide tube 21 and the tubular layer 22, the distance between the tubular layer 22 and the tubular layer 23, the distance between the tubular layer 23 and the tubular layer 24, and the distance between the tubular layer 24 and the tubular layer 25 are transmitted through the core 1 of the optical fiber. It is determined in consideration of the conditions of Bragg reflection (Bragg diffraction) with respect to the wavelength of light to be emitted.
- each of the support members 7a to 7l disposed along the longitudinal direction of the optical fiber between the core guide tube 21 and the tubular layers 22 to 25 is a single support. It is different from the optical fiber support members 3a to 3l according to the first embodiment of the present invention in that the support member is made of a plate.
- the support plates 7a to 7l constituting the support member have, for example, an elongated rectangular (bar-shaped) cross-sectional shape in a cross-sectional view perpendicular to the longitudinal direction of the optical fiber, but are not limited thereto.
- the support plates 7a to 7l constituting the support member may be a columnar shape or a convex lens shape having a circular sectional shape including a flat circle such as an ellipse.
- a plurality of (three) wall-shaped (plate-shaped) support plates 7a, 7e, 7i are connected to the core guide tube 21 and the tubular layer 22 as support members. It is provided as.
- a plurality of (three) wall-shaped support plates 7b, 7f, and 7j are provided as support members so as to connect the tubular layer 22 and the tubular layer 23.
- a plurality of (three) wall-shaped support plates 7c, 7g, and 7k are provided as support members so as to connect the tubular layer 23 and the tubular layer 24.
- a plurality of (three) wall-shaped support plates 7d, 7h, 7l are provided as support members so as to connect the tubular layer 24 and the tubular layer 25.
- the material of the support plates 7a to 7l constituting the support member glass such as quartz glass, polymer, or the like can be used.
- the support plates 7a to 7l are preferably made of the same material as the core guide tube 21 and the tubular layers 22 to 25.
- the viscosity of the material constituting the support plates 7a to 7l is preferably the same as the viscosity of the material constituting the core guide tube 21 and the tubular layers 22 to 25. That is, if the support plates 7a to 7l, the core guide tube 21 and the tubular layers 22 to 25, or the viscosity characteristics of these materials are the same, the support plates 7a to 7l, the core guide tube 21 and the tubular layers 22 to 25 are the same.
- the support plates 7a to 7l constituting the support member may be made of a material different from that of the core guide tube 21 and the tubular layers 22 to 25. Further, the support plates 7a to 7l constituting the support member may be made of different materials.
- the support plates 7a to 7l constituting the support member are spaced apart from each other in the circumferential direction of the optical fiber.
- a distance between the support members is wider than twice the thickness of the air layer between the core guide tube 21 and the tubular layers 22 to 25 sandwiching the support plates 7a to 7l.
- the support member interval S1 between the support plate 7a and the support plate 7e spaced from the support plate 7a clockwise by about 120 ° in the circumferential direction is determined by the core guide tube 21 and the tubular layer 22. It is wider than twice the thickness of the air layer (air gap) G1.
- the support member spacing S2 between the support plate 7a and the support plate 7i spaced from the support plate 7a counterclockwise by about 120 ° in the circumferential direction is the thickness of the air layer between the core guide tube 21 and the tubular layer 22. It is wider than twice (air gap) G1.
- the wall thickness (plate thickness) measured in the circumferential direction of the optical fibers of the support plates 7a to 7l constituting the support member is transmitted through the core 1. It is preferable to set the thickness so that the mode of the light to be localized cannot be localized.
- the thickness of the walls of the support plates 7a to 7l in the circumferential direction of the optical fiber depends on the wavelength of light transmitted through the core 1, so that, for example, when the wavelength of light to be used is 1 ⁇ m, the optical fiber
- the thickness of the walls of the support plates 7a to 7l in the circumferential direction is preferably set to be less than 1 ⁇ m shorter than the wavelength.
- the thickness of the walls of the support plates 7a to 7l in the circumferential direction of the optical fiber is set to a thickness at which a mode corresponding to the wavelength of light transmitted through the core 1 cannot be localized, or as a specific example, the support plate 7a.
- FIG. 13 the case where three support plates 7a to 7l are arranged in each air layer constituting the multilayer clad part 2 is illustrated, but the support distributed to the air layers existing at different radial positions is illustrated.
- the number of plates is not particularly limited.
- the number of support plates disposed in each air layer is preferably as small as possible from the viewpoint of transmission characteristics, but is preferably 3 or more from the viewpoint of the mechanical strength and stability of the structure.
- FIG. 13 illustrates the case where the support plates 7a to 7l are spaced apart at equal intervals of about 120 °, but the support plates 7a to 7l are spaced apart from each other with different support member intervals. It may be.
- the support plates 7a to 7d arranged in the air layers at different radial positions constituting the multilayer clad part 2 are arranged on a straight line along the same radial direction.
- the support plates 7e to 7h arranged in the air layers at different radial positions are arranged on a straight line along the same radial direction.
- the support plates 7i to 7l arranged in the air layers at different radial positions are arranged on a straight line along the same radial direction. Note that the support plates 7a to 7l arranged in the air layers at different radial positions may be arranged on a straight line while being shifted along different radial directions.
- the support member spacing between the support plates 7a to 7l in the circumferential direction of the optical fiber is such that the core guide tube 21 and the tubular layers 22 to sandwich the support plates 7a to 7l. Since it is wider than twice the thickness of the air layer between 25, the number of support plates 7a to 7l can be reduced, and light leakage through the support plates 7a to 7l can be suppressed.
- optical fiber manufacturing method Next, an example of an optical fiber manufacturing method according to the second embodiment of the present invention will be described.
- the manufacturing method of the optical fiber described below is an example, and as long as it is the range of the meaning described in the claim, it cannot be overemphasized by various manufacturing methods other than this.
- a tubular core preform 41 made of quartz or the like and a plurality of tubular layer preforms 42 to 45 are arranged concentrically and periodically spaced from each other. Then, the ends of the core base material portion 41 and the tubular layer base material layers 42 to 45 are temporarily fixed with the tape 8 to maintain the air gap between the core base material portion 41 and the tubular layer base material layers 42 to 45. . Note that an adhesive or the like may be used instead of the tape 8.
- FIG. 4B An upper plate (round plate) 5 made of quartz glass or the like as shown in FIG. Rectangular openings (holes) 51a to 51c, 52a to 52c, 53a to 53c, and 54a to 54c are cut out using drills or the like at positions where a plurality of plate-like members (support base materials) are passed through the upper plate 5. . Further, a bottom plate (round plate) 6 facing the upper plate 5 shown in FIG. 4B is prepared separately. The bottom plate 6 may also be provided with openings corresponding to the openings 51a to 51c, 52a to 52c, 53a to 53c, and 54a to 54c of the upper plate 5. Then, the temporarily fixed core base material portion 41 and one end of the plurality of tubular layer base material layers 42 to 45 and the bottom plate 6 shown in FIG.
- a plurality of (12 sheets) plate members such as glass plates (supporting mothers) are provided in the openings (holes) 51a to 51c, 52a to 52c, 53a to 53c, 54a to 54c of the upper plate 5, respectively.
- the plate member is inserted while being aligned between the core base material portion 41 and the plurality of tubular layer base material layers 42 to 45.
- the plate-like member is fused by applying heat or the like to the inner surface or the outer surface of the core base material portion 41 and the plurality of tubular layer base material layers 42 to 45.
- the plurality of plate-like members 9a to 9l are integrated between the core base material portion 41 and the tubular layer base material layers 42 to 45 so as to be separated from each other in the circumferential direction.
- a fixed fiber preform 4 is obtained.
- FIG. 13 Thereafter, a drawing process for heating and drawing the fiber preform 4 is performed, whereby the optical fiber shown in FIG. 13 is completed.
- a plurality of support plates 7a to 7l are formed one by one from the plurality of plate-like members 9a to 9l.
- the spacing between the support members 7a-7l in the circumferential direction of the optical fiber is such that the air layer between the core guide tube 21 and the tubular layers 22-25 sandwiching the support plates 7a-7l. It is formed to be wider than twice the thickness. In this way, the optical fiber shown in FIG. 13 is completed.
- the support member interval which is the interval between the support members in the circumferential direction of the optical fiber between the support plates 7a to 7l, is different from the support plates 7a to 7l. It is formed to be wider than twice the thickness of the air layer between the sandwiched core guide tube 21 and the tubular layers 22-25. As a result, the number of support plates 7a to 7l can be reduced as compared with the first and second comparative examples, and an optical fiber capable of suppressing deterioration of transmission characteristics due to the support plates 7a to 7l can be realized.
- a plurality of support plates 7a to 7l are formed one by one from the plurality of plate-like members 9a to 9l. Therefore, since the thickness of the support plates 7a to 7l can be made thinner than that of the first and second comparative examples, light leakage through the support plates 7a to 7l can be reduced.
- the number of support plates arranged in each air layer is different from that of the optical fiber according to the second embodiment of the present invention.
- one support plate 7a to 7d may be disposed in each air layer.
- the support member interval in the circumferential direction of the optical fiber between the support plates 7a to 7d is twice the thickness of the air layer between the core guide tube 21 and the tubular layers 22 to 25 sandwiching the support plates 7a to 7l. Wider than.
- the support member interval S1 between both side surfaces of the support plate 7a in the circumferential direction of the optical fiber is the thickness of the air layer between the core guide tube 21 and the tubular layer 22 sandwiching the support plate 7a. It is wider than twice G1.
- each air layer may be arranged in each air layer, in addition to support plates 7a to 7d.
- the support plate may be arrange
- the number of support plates arranged in each air layer is not limited. Note that, in at least one of the air layers along the radial direction, the distance between the support members in the circumferential direction of the optical fiber is the thickness of the air layer (air gap) in which the support members are disposed. It only needs to be wider than twice.
- the support plate disposed in each air layer may be disposed including each position of each air layer in a different radial direction.
- the support plates 7a and 7e, support plates 7b and 7f, support plates 7c and 7g, and support plates 7d and 7h are disposed in each air layer.
- the support plates 7a to 7d are arranged so as to be shifted along different radial directions.
- the support plates 7e to 7h are arranged so as to be shifted along different radial directions.
- the support plates 7a and 7e are intermittently disposed along the same radial direction.
- the support plates 7c and 7g are 90 ° apart from the support plates 7a and 7e, and are intermittently disposed along the same radial direction.
- the support plates 7b and 7f are shifted from the support plates 7c and 7g by 90 °, and are intermittently disposed along the same radial direction.
- the support plates 7d and 7h are shifted from the support plates 7b and 7f by 90 °, and are intermittently disposed along the same radial direction.
- the number of support plates may be different for each air layer having a different radial position.
- the number of support plates 7a to 7j may increase in the outer air layer along the radial direction. That is, one support plate 7a is disposed in the innermost air layer along the radial direction.
- Two support plates 7b and 7c are arranged in the second air layer from the inside.
- Three support plates 7d to 7f are arranged in the third air layer from the inside.
- Four support plates 7g to 7j are disposed in the outermost air layer.
- the number of support members arranged in the air layer close to the center side is smaller than the number of support members arranged in the air layer close to the outer peripheral side, so that the support member spacing can be adjusted in all air layers. It may be wider than twice the thickness of the air layer.
- support plates may be arranged at different support member intervals along the circumferential direction of the optical fiber.
- three support plates 7a, 7e, 7i, support plates 7b, 7f, 7j, support plates 7c, 7g, 7k, and support plates 7d, 7h, 7l are provided for each air layer.
- These support plates 7a, 7e, 7i, support plates 7b, 7f, 7j, support plates 7c, 7g, 7k, and support plates 7d, 7h, 7l are provided for each air layer.
- the support member interval S1 between the support plate 7a and the support plate 7e in the circumferential direction of the optical fiber is wider than the support member interval S2 between the support plate 7a and the support plate 7i.
- an optical fiber according to a fifth modification of the second embodiment of the present invention includes a core 1x having a solid structure made of glass or the like, and an air layer around the core 1x.
- This is an air-clad fiber (holey fiber) including a tubular layer 2x disposed via a different from the configuration of an air-core fiber that is an optical fiber according to the second embodiment of the present invention shown in FIG.
- a clad layer for confining light is constituted by the air layer and the tubular layer 2x.
- a plurality of support plates 7a to 7c are disposed in the air layer between the core 1x and the tubular layer 2x.
- the number of support plates 7a to 7c can be reduced as compared with the air-clad fiber according to the comparative example shown in FIG. 31, and the deterioration of transmission characteristics can be suppressed.
- FIG. 19B an air clad fiber having a plurality of tubular layers 22 to 25 arranged concentrically around the core 1x may be used.
- the air clad fiber shown in FIG. 19B is different from the structure of the air core fiber shown in FIG. 13 in that the core 1x has a solid structure.
- a Bragg-type hole core fiber according to an example of the second embodiment of the present invention has a hole core 1 defined in a tubular layer 21, and the tubular layers 21 to 25 are formed.
- four support plates 7a to 7p are arranged in each air layer sandwiched between the two.
- FIG. 20B shows a light intensity distribution of the Bragg-type hole core fiber shown in FIG. In FIG. 20 (b), the higher the light intensity level, the finer the hatching, and the light intensity is shown stepwise. From FIG.
- the light intensity is highest at the position corresponding to the hole core 1, but the light intensity distribution is also observed at the positions corresponding to the support plates 7a to 7p, and light leaks through the support plates 7a to 7p. It can be seen that has occurred.
- FIG. 21 shows the result of the confinement loss simulation in the case where the number of tubular layers is four, the support plate (bridge) is not provided, and 18.5 nm and 38 nm in the structure of FIG.
- FIG. 22 shows the result of the confinement loss simulation in the case of the structure of FIG. 20A, in which the number of tubular layers is 5, the support plate (bridge) is not provided, and 18.5 nm and 38 nm.
- the confinement loss characteristics are affected by the thickness of the support plate, each support plate is thin and the number is small, so that sufficiently low confinement loss characteristics can be obtained. I understand that Even in other structures, it can be considered that there is an advantage from the viewpoint of suppressing leakage loss that the support plate can be made thin and small.
- the support member spacing between the support members 3a to 3l in the circumferential direction of the optical fiber is the support member.
- the air layer thickness (air gap) G1 is larger than twice the air layer G1 in which 3a to 3l are arranged is exemplified, at least one of the air layers along the radial direction has the support member spacing S1. , S2 and the air gap G1 are included in the scope of the present invention.
- the multilayer clad part 2 has exemplified the structure having four tubular layers 22 to 25 along the radial direction.
- the number of the tubular layers 22 to 25 is not limited as long as it has at least one air layer. For example, it may have one, two, or three tubular layers, and may have five or more tubular layers along the radial direction.
- the core 1x has a solid structure (solid core) made of glass or the like, and a portion (refractive index changing portion) 1y having a refractive index different from the core 1x in the core 1x. May be included.
- the refractive index changing portion 1y extends parallel to the longitudinal direction of the optical fiber and is located at the center of the core 1x in a cross section perpendicular to the longitudinal direction of the optical fiber.
- the refractive index changing portion 1y has a refractive index higher than that of the core 1x and functions as a central core.
- the refractive index of the refractive index changing portion 1y may be lower than the refractive index of the core 1x depending on the type of optical fiber.
- the size, number, and arrangement position of the refractive index changing portion 1y are not particularly limited, and can be set as appropriate according to the type of the optical fiber.
- the support plates 7a to 7l constituting the support member may be solid bodies having a circular shape in a cross section perpendicular to the longitudinal direction of the optical fiber.
- FIG. 24 illustrates a circular cross-sectional shape, but the present invention is not limited to this, and for example, it may have a polygonal cross-sectional shape such as a triangle or a quadrangle.
- the support plates 7a to 7l constituting the support member may have a ring shape in a cross section perpendicular to the longitudinal direction of the optical fiber.
- the support plates 7a to 7d, 7e to 7h, and 7i to 7l constituting the support member may include different shapes.
- the shapes of the support plates 7a to 7l can be set as appropriate according to the type of optical fiber.
- the optical fibers according to the first and second embodiments of the present invention it becomes possible to construct a new optical system utilizing various unique characteristics.
- the optical fibers according to the first and second embodiments of the present invention since most of the core is surrounded by air, it is the ultimate high NA (light collecting property) whether it is an air core or a glass core. It is clear that is obtained. For this reason, it is possible to use it as a fiber which condenses and propagates LED, sunlight, etc. which are difficult to condense.
- the optical fibers according to the first and second embodiments of the present invention can be applied to sterilization, water purification, lighting, plant factories, visible light communication, solar power generation, and the like.
- the fiber loss characteristic when applied to solar lighting, it is considered as an added value to selectively transmit light of a specific wavelength.
- the fiber loss characteristic by optimizing the fiber loss characteristic, only visible light necessary for sunlight illumination is sent by an optical fiber, and the infrared rays that cause harmful ultraviolet rays and heat are blocked by the optical fiber. It is good also as a system.
- the short wavelength on the ultraviolet side can be blocked by increasing the confinement loss by, for example, band gap cutoff, ultraviolet absorption edge adjustment, impurity (for example, metal) absorption adjustment, glass defect absorption adjustment, confinement loss adjustment, bending loss adjustment, and the like.
- the long wavelength on the infrared side can be blocked by increasing the confinement loss by band gap blocking, impurity absorption (for example, OH absorption) adjustment, confinement loss adjustment, bending loss adjustment, or the like.
- a specific wavelength is selectively propagated by optimizing the fiber loss characteristic as shown in FIG. Can do. Therefore, since it is not necessary to incorporate an optical system for blocking extra light, a simple system can be constructed.
- the application of blocking other than the necessary wavelength is not limited to the application to solar lighting, and various other application developments are conceivable.
- a high power delivery application can be considered.
- the high NA characteristic is important from the viewpoint of the ability to collect a large amount of light and achieve high power even in the high power field.
- the characteristics of suppressing nonlinear distortion at the time of high power input and suppressing light leakage when bent are characteristics that can be realized by the optical fibers according to the first and second embodiments of the present invention. It can be said that the characteristics suitable for the application are obtained.
- a structure including independent tubular layers 21 and 22 around the core 1x and including two or more air layers is used, and the core 1x and the surrounding tubular layer 21 are used.
- the Gaussian-type or flat-type circular profile and ring profile required for processing applications can be formed. That is, a circular profile can be formed by selectively entering light into the inner core 1x, and a ring profile can be formed by selectively entering light into the outer tubular layers 21 and 22.
- Switching of the incident position may be performed manually on a stage, for example, or a mechanism that automatically switches the position may be introduced. As shown in FIG.
- the core 1 is air, and the circular profile is similarly applied to a hollow core type optical fiber including tubular layers 21 to 24 around the core 1 and including two or more air layers.
- a ring profile can be realized, and in the case of a hollow core, high power resistance is also obtained.
- hole-clad fibers and hole-core fibers an application in which a cooling gas is allowed to flow through a hole ring (air layer) on the outer periphery to cool the fiber at high power is also conceivable. Also in this case, since there are few support plates arranged in the hole ring (air layer), it is not necessary to individually introduce a cooling gas or liquid into a so-called subdivided room, and the medium can be introduced. It becomes easy.
- the optical fiber of the present invention can have characteristics such as low loss, low delay, low nonlinearity, low bending loss, interference with a medium, and excellent environmental resistance characteristics, and transmission of datacom and telecom.
- characteristics such as low loss, low delay, low nonlinearity, low bending loss, interference with a medium, and excellent environmental resistance characteristics, and transmission of datacom and telecom.
- Various applications such as a medium, an amplification medium, a sensor using interference, and a transmission medium used in a special environment such as radiation can be considered.
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Abstract
Description
<光ファイバの構成>
本発明の第1の実施形態に係る光ファイバは、図1に示すように、コア(空孔コア)1を内側に定義し、光ファイバの長手方向に延伸する管状のコアガイド管21と、コアガイド管21の周囲に複数の空気層(エアクラッド)を挟んで周期構造を構成するように多層に配置され、光ファイバの長手方向に延伸する多層クラッド部2とを備えるブラッグ型のエアコアファイバである。
次に、図3~図6を参照しながら、本発明の第1の実施形態に係る光ファイバの製造方法の一例を説明する。なお、以下に述べる光ファイバの製造方法は一例であり、特許請求の範囲に記載した趣旨の範囲であれば、これ以外の種々の製造方法により実現可能であることは勿論である。
本発明の第1の実施形態の第1の変形例に係る光ファイバとして、各空気層に配置される支持部材の個数が、本発明の第1の実施形態に係る光ファイバと異なる場合を説明する。例えば図7(a)に示すように、各空気層に1個ずつ、内側の空気層から支持部材3a、支持部材3b、支持部材3c、支持部材3dが配置されていてもよい。例えば支持部材3aに着目した場合、光ファイバの周方向における支持部材3a同士、即ち支持部材3aの側面同士の支持部材間隔S1が、支持部材3aが配置されている空気層の厚さG1の2倍よりも広い。
本発明の第1の実施形態の第2の変形例に係る光ファイバとして、各空気層に配置される支持部材が異なる半径方向となる各空気層のそれぞれの位置を含んで配置されていてもよい。例えば、図10(a)に示すように、各空気層に2個ずつ、支持部材3a,3e、支持部材3b,3f、支持部材3c,3g、支持部材3d,3hが配置されている。図10(a)の上部において、支持部材3a~3dが、異なる半径方向に沿ってずれて配置されている。図10(a)の下部において、支持部材3e~3hが、異なる半径方向に沿ってずれて配置されている。
本発明の第1の実施形態の第3の変形例に係る光ファイバとして、支持部材の個数が、半径位置の異なる空気層毎に異なっていてもよい。例えば、図11(a)に示すように、半径方向に沿って外側の空気層ほど支持部材3a,3b,3c,3d,3f,3g,3h,3k,3l,3pの個数が多くてもよい。即ち、半径方向に沿って最も内側の空気層には、1個の支持部材3aが配置されている。内側から2番目の空気層には、2個の支持部材3b,3fが配置されている。内側から3番目の空気層には、3個の支持部材3c,3g,3kが配置されている。最も外側の空気層には、4個の支持部材3d,3h,3l,3pが配置されている。
本発明の第1の実施形態の第4の変形例に係る光ファイバとして、光ファイバの周方向において支持部材が異なる支持部材間隔で配置されていてもよい。例えば図11(b)に示すように、各空気層に3個ずつ支持部材3a~3d、支持部材3e~3h、支持部材3i~3lが、同一の半径方向に沿って配置されている。そして、最も内側の空気層に着目した場合、光ファイバの周方向における支持部材3aと支持部材3eの支持部材間隔S1が、支持部材3aと支持部材3iの光ファイバの周方向に沿った支持部材間隔S2よりも広い。
本発明の第1の実施形態の第5の変形例に係る光ファイバは、図12(a)に示すように、ガラス等からなる中実構造を有するコア1xと、コア1xの周囲に空気層を介して配置された管状層2xを備えるエアクラッドファイバ(ホーリーファイバ)である点が、図1に示した本発明の第1の実施形態に係る光ファイバであるエアコアファイバの構成と異なる。
<光ファイバの構成>
本発明の第2の実施形態に係る光ファイバは、図13に示すように、コア(空孔コア)1を内側に定義し、光ファイバの長手方向に延伸する管状のコアガイド管21と、コアガイド管21の周囲に複数の空気層(エアクラッド)を挟んで周期構造を構成するように多層に配置され、光ファイバの長手方向に延伸する多層クラッド部2とを備えるブラッグ型のエアコアファイバである。
次に、本発明の第2の実施形態に係る光ファイバの製造方法の一例を説明する。なお、以下に述べる光ファイバの製造方法は一例であり、特許請求の範囲に記載した趣旨の範囲であれば、これ以外の種々の製造方法により実現可能であることは勿論である。
本発明の第2の実施形態の第1の変形例に係る光ファイバとして、各空気層に配置される支持板の個数が、本発明の第2の実施形態に係る光ファイバと異なっていてもよい。例えば図16(a)に示すように、各空気層に1枚ずつ支持板7a~7dが配置されていてもよい。この場合も、支持板7a~7d同士の光ファイバの周方向における支持部材間隔が、支持板7a~7lを挟むコアガイド管21及び管状層22~25の間の空気層の厚さの2倍よりも広い。例えば、支持板7aに着目した場合、光ファイバの周方向における支持板7aの両側面同士の支持部材間隔S1が、支持板7aを挟むコアガイド管21及び管状層22の間の空気層の厚さG1の2倍よりも広い。
本発明の第2の実施形態の第2の変形例に係る光ファイバとして、各空気層に配置される支持板が異なる半径方向となる各空気層のそれぞれの位置を含んで配置されていてもよい。例えば、図17(a)に示すように、各空気層に2個ずつ、支持板7a,7e、支持板7b,7f、支持板7c,7g、支持板7d,7hが配置されている。図17(a)の上部において、支持板7a~7dが、異なる半径方向に沿ってずれて配置されている。図17(a)の下部において、支持板7e~7hが、異なる半径方向に沿ってずれて配置されている。
本発明の第2の実施形態の第3の変形例に係る光ファイバとして、支持板の個数が、半径位置の異なる空気層毎に異なっていてもよい。例えば、図18(a)に示すように、半径方向に沿って外側の空気層ほど支持板7a~7jの個数が多くていてもよい。即ち、半径方向に沿って最も内側の空気層には、1枚の支持板7aが配置されている。内側から2番目の空気層には、2個の支持板7b,7cが配置されている。内側から3番目の空気層には、3個の支持板7d~7fが配置されている。最も外側の空気層には、4個の支持板7g~7jが配置されている。また、中心側に近い空気層に配置される支持部材の個数を、外周側に近い空気層に配置される支持部材の個数よりも少なくすることにより、すべての空気層において支持部材間隔を、対応する空気層の厚さの2倍よりも広くてもよい。
本発明の第2の実施形態の第4の変形例に係る光ファイバとして、光ファイバの周方向に沿って支持板が異なる支持部材間隔で配置されていてもよい。例えば図18(b)に示すように、各空気層に3個ずつ支持板7a,7e,7i、支持板7b,7f,7j、支持板7c,7g,7k、支持板7d,7h,7lが、同一の半径方向に沿ってそれぞれ直線上に配置されている。そして、最も内側の空気層に着目した場合、光ファイバの周方向における支持板7aと支持板7eの支持部材間隔S1が、支持板7aと支持板7iの支持部材間隔S2よりも広い。
本発明の第2の実施形態の第5の変形例に係る光ファイバは、図19(a)に示すように、ガラス等からなる中実構造を有するコア1xと、コア1xの周囲に空気層を介して配置された管状層2xを備えるエアクラッドファイバ(ホーリーファイバ)である点が、図13に示した本発明の第2の実施形態に係る光ファイバであるエアコアファイバの構成と異なる。
本発明の第2の実施形態の実施例に係るブラッグ型の空孔コアファイバは、図20(a)に示すように、管状層21内に空孔コア1が定義され、管状層21~25に挟まれた各空気層に4個ずつ支持板7a~7pを配置した構造である。図20(a)に示したブラッグ型の空孔コアファイバの光強度分布を図20(b)に示す。図20(b)では、光強度のレベルが高いほどハッチングを細かくして光強度を段階的に示している。図20(b)から、空孔コア1に対応する位置では光強度が最も高いが、支持板7a~7pに対応する位置でも光強度分布が認められ、支持板7a~7pを介して光漏れが発生していることが分かる。
上記のように、本発明は第1及び第2の実施形態によって記載したが、この開示の一部をなす論述及び図面は本発明を限定するものであると理解すべきではない。この開示から当業者には様々な代替実施の形態、実施例及び運用技術が明らかとなろう。
1y…屈折率変化部
2,102…多層クラッド部
2x,102x…管状層
3a~3x,7a~7p…支持部材
4…ファイバ母材
5…上板
6…底板
8…テープ
21,121…コアガイド管
22~25,122~124…管状層
31a~31l,32a~32l,33a~33l,34a~34l,131~133…支持板
41…コア母材部
42~45…管状層母材層
51a~51c,52a~52c,53a~53c,54a~54c…開口部
61a~61d,62a~62d,63a~63d…キャピラリ
Claims (20)
- コアと、
前記コアの周囲に空気層を介して同心で配置された管状層と、
前記空気層に配置され、前記コアと前記管状層とを接続する支持部材と
を備えた光ファイバであって、
前記光ファイバの長手方向の断面視において、前記光ファイバの周方向における前記支持部材同士の支持部材間隔が、前記支持部材が配置されている前記空気層の厚さの2倍よりも広いことを特徴とする光ファイバ。 - 前記支持部材が、1枚の支持板、又は壁状に対をなす2枚の支持板からなることを特徴とする請求項1に記載の光ファイバ。
- 前記支持部材が、1枚の支持板、又は前記支持部材間隔より狭い部材内壁間隔で壁状に対をなす2枚の支持板からなることを特徴とする請求項1に記載の光ファイバ。
- 前記コアが、管状のコアガイド管の内側の空孔コアであることを特徴とする請求項1~3のいずれか1項に記載の光ファイバ。
- 前記コアがガラスからなり、
前記空気層と前記空気層を介して配置された管状層とにより光を閉じ込めるクラッド層を構成することを特徴とする請求項1~3のいずれか1項に記載の光ファイバ。 - 前記コアがガラスからなり、
前記コアの中に前記コアと屈折率が異なる部分を含むことを特徴とする請求項1~3、5のいずれか1項に記載の光ファイバ。 - 前記管状層が、石英ガラス又はドーパントがドープされた石英ガラスであることを特徴とする請求項1~6のいずれか1項に記載の光ファイバ。
- 前記支持部材が前記光ファイバの周方向に沿って複数離間して配置され、前記光ファイバの周方向における異なる前記支持部材同士の前記支持部材間隔が、対応する前記空気層の厚さの2倍よりも広いことを特徴とする請求項1~7のいずれか1項に記載の光ファイバ。
- 前記支持部材と前記管状層が同じ粘度を有することを特徴とする請求項1~8のいずれか1項に記載の光ファイバ。
- 前記支持部材と前記管状層が同じ材料からなることを特徴とする請求項1~9のいずれか1項に記載の光ファイバ。
- 前記1枚の支持板又は前記壁状に対をなす2枚の支持板の、それぞれ支持板の前記周方向に測られる厚さが、前記コア中を伝送される光のモードが局在できない寸法であることを特徴とする請求項2又は3に記載の光ファイバ。
- 前記1枚の支持板又は前記壁状に対をなす2枚の支持板の、それぞれ支持板の前記光ファイバの周方向における厚さが、前記コアを伝送される光の波長より薄いことを特徴とする請求項2又は3に記載の光ファイバ。
- 前記管状層が、複数の空気層を挟んで周期的に複数層同心で配置されており、
前記複数の空気層のそれぞれに前記支持部材が配置され、
少なくとも1つ以上の前記空気層において、前記支持部材間隔が、対応する前記空気層の厚さの2倍よりも広いことを特徴とする請求項1~12のいずれか1項に記載の光ファイバ。 - 前記複数の空気層のそれぞれに配置される前記支持部材が、同一半径方向に沿ってそれぞれ直線上に配列されていることを特徴とする請求項13に記載の光ファイバ。
- 前記支持部材が、異なる半径方向となる前記複数の空気層のそれぞれの位置を含んで配置されていることを特徴とする請求項13に記載の光ファイバ。
- 前記支持部材の個数が、前記複数の空気層毎に異なることを特徴とする請求項14又は15に記載の光ファイバ。
- 中心側に近い前記空気層に配置される前記支持部材の個数が、外周側に近い前記空気層に配置される前記支持部材の個数よりも少なく、すべての前記空気層において前記支持部材間隔が、対応する前記空気層の厚さの2倍よりも広いことを特徴とする請求項16に記載の光ファイバ。
- 請求項1~17のいずれか1項に記載の光ファイバを用いたことを特徴とする光システム。
- コア母材部の周囲に空気層を挟んで管状の管状層母材層を同心で配置する工程と、
前記コア母材部と前記管状層母材層の間を接続するように前記空気層中に支持母材部を挿入してファイバ母材を形成する工程と、
前記コア母材部をコア又はコアガイド管に、前記管状層母材層を管状層に、前記支持母材部を支持部材にするように、前記ファイバ母材を溶融して線引きする工程
とを含む光ファイバの製造方法であって、前記光ファイバの長手方向の断面視において、前記光ファイバの周方向における前記支持部材同士の支持部材間隔を、前記支持部材が配置されている前記空気層の厚さの2倍よりも広くすることを特徴とする光ファイバの製造方法。 - 前記支持母材部がキャピラリであり、
前記線引きする工程は、前記キャピラリの壁を、それぞれ互いに対をなす支持板にするように線引きすることを特徴とする請求項19に記載の光ファイバの製造方法。
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JP2017530782A JPWO2017150699A1 (ja) | 2016-03-03 | 2017-03-03 | 光ファイバ、光システム及び光ファイバの製造方法 |
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EP3948373A1 (en) * | 2019-04-03 | 2022-02-09 | ASML Netherlands B.V. | Optical fiber |
CN112014920B (zh) * | 2020-08-31 | 2022-04-12 | 北京航空航天大学 | 一种基于外加反谐振层的空芯光子带隙光纤 |
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