CN1238739C - Double cladding optical fiber having external cladding as pump light guide, and its coating mould - Google Patents
Double cladding optical fiber having external cladding as pump light guide, and its coating mould Download PDFInfo
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- CN1238739C CN1238739C CN 200410018754 CN200410018754A CN1238739C CN 1238739 C CN1238739 C CN 1238739C CN 200410018754 CN200410018754 CN 200410018754 CN 200410018754 A CN200410018754 A CN 200410018754A CN 1238739 C CN1238739 C CN 1238739C
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Abstract
The present invention relates to optical fiber and a coating mould. The present invention solves the problems of small numerical apertures, high requirements of coupling technology of pumping light and high cost. Outer cladding of the present invention can be used as a protection layer of the optical fiber. The inner cladding and the outer cladding are used as pumping light paths, and complete the transmission and the coupling to a fiber core of the pumping light together. The inner cladding is composed of inorganic materials which can be matched and welded with matrix materials of the fiber core, the cross-section is circular, and the refractivity of the inner cladding equals to or is slightly larger than that of the outer cladding. The outer cladding adopts polymer optical materials, the cross-section is noncircular and can be in the shape of a rectangle, a rounded rectangle, an octagon, a cake, a D, etc. A coating hole at the middle of the mould is in the shape of a funnel, namely that the upper part is a back taper shape, and the lower part is provided with a constant section hole, the shape of which is identical with that of the outer cladding. When the present invention is used, the outer side of the outer cladding is surrounded with media with low refractivity, such as gas, water, etc., the outer surface of the outer cladding changes into a pumping light waveguide interface, the numerical aperture of the waveguide is large and is suitable for cheap high power optical fiber lasers and optical fibre amplifiers which are coupled with high power pumping light side edges.
Description
[technical field]: the present invention relates to a kind of light transmitting fiber, relate in particular to a kind of doubly clad optical fiber and special-purpose coating mould thereof that constitutes high-capacity optical fiber laser and fiber amplifier.
[background technology]: high-power fiber laser and fiber amplifier generally adopt doubly clad optical fiber, and the common double cladded-fiber is made up of the fiber cores that is mixed with the laser active material, inner cladding, surrounding layer and protective seam four parts.The refractive index maximum of fiber cores wherein, the refractive index of inner cladding is greater than the refractive index of surrounding layer; Outsourcing layer is a polymeric optical material, and the optical fiber jacket cross section is generally circle; Fiber cores is made of inorganic optical material doping laser active materials such as quartzy, glass and crystal, and inner cladding is to be made of the inorganic optical materials such as quartz, glass and crystal that can mate welding with the fibre core matrix material, and its cross section can be circle.Because the inner cladding bore is much larger than the fibre core bore, enter inner cladding so can converge more pump light, and pump light constrained in the inner cladding propagate, and then be coupled to fibre core, finish excitation process.
Though the doubly clad optical fiber of rectangular inner cladding has many good qualities, mainly be not need prefabricated rods is done extra optical-mechanical processing, and make technology simpler, and also having when pumping source is the LD of magnetic tape trailer fibre, the size match between the circular quartzy covering is easy to be of coupled connections etc.But there is following shortcoming in the doubly clad optical fiber of rectangular inner cladding: promptly perfectly circular symmetry makes a large amount of pump light in the inner cladding become spiral light, can not reach fibre core forever in the process of transmission, thereby high light light conversion efficiency can not be arranged.In order to overcome this defective, people are designed to the doubly clad optical fiber of noncircular inner claddings with the inner cladding cross section structure, as square, rectangle, D type etc., and referring to [UnitedStates Patent 5,533,163], and the doubly clad optical fiber of non-concentric inner cladding; Also have non-circle to reverse the doubly clad optical fiber of shape inner cladding, referring to [United States Patent 6,157,763].Though these optical fiber have solved end-pumped method high light light conversion efficiency is arranged, because the numerical aperture of the inner cladding of these doubly clad optical fibers is smaller, so doubly clad optical fiber in the past, expensive to the coupling technique of the end pumping price of having relatively high expectations, and be difficult to obtain pump light side coupling efficiently.Therefore, former doubly clad optical fiber is not suitable for making cheap high-power double cladding optical fiber laser and fiber amplifier.
Known optical fiber polymer-coated can be adopted the device that uses nozzle and applicator die, referring to technology [Chinese patent: 98107022.1] formerly.But the die hole of those applicator dies all is circular, can't coat the non-circular surrounding layer of optical fiber.
[summary of the invention]: the objective of the invention is to overcome the problems referred to above that existing doubly clad optical fiber exists when making high-capacity optical fiber laser and fiber amplifier, a kind of higher light light conversion efficiency that both had is provided, has bigger numerical aperture again, coupling technique to pump light requires fairly simple simultaneously, and can make cheaply that the surrounding layer of fiber laser and fiber amplifier is the doubly clad optical fiber of pump light waveguide, and the particular manufacturing craft that coats optical fiber.
Surrounding layer of the present invention is the doubly clad optical fiber of pump light waveguide; have only fiber cores, inner cladding and surrounding layer three parts; the protective seam that does not have ordinary optic fibre, and by the double partial function of doing protective seam of surrounding layer, the outside surface of surrounding layer is the interface of pump light waveguide simultaneously.Be that described covering is meant the transmission that is all the pump light passage, finishes pump light jointly and inner cladding and surrounding layer to the fibre core coupling, fiber cores is followed successively by inner cladding outward and the materials such as glass of inner cladding is had the surrounding layer of protection crackle generation effect.
The cross section of surrounding layer is following any non-circular: rectangle, round rectangle, square, rounded square, D shape, middle part are that rectangle or square one or both ends are that combination shape, the rectangular pin of part circular goes one to four residue shape, circular pegs behind the angle to go one or two residue shape behind the not a half circle.
Inner cladding is made for inorganic optical materials such as quartz, glass and crystal, and its cross section is circular.Fiber cores is made for inorganic optical material doping laser active materials such as quartz, glass and crystal.Wherein, cladding refractive index minimum, the refractive index of inner cladding equal or less times greater than the refractive index of surrounding layer, the refractive index maximum of fiber cores.
A kind ofly be specifically designed to that to make surrounding layer be the coating mould of the doubly clad optical fiber of pump light waveguide, the die matrix that has a coating hole in the middle of this mould comprises, this coating hole is an infundibulate, be that the first half is a back taper, Lower Half is the uniform cross section hole, and its cross section can be following any non-circular: rectangle, round rectangle, square, rounded square, D shape, middle part are that rectangle or square one or both ends are combination shape, the rectangle of part circular prune the residue shape behind one or two not a half circle of residue shape, circle behind one to four angle of pruning.
Advantage of the present invention and good effect: doubly clad optical fiber of the present invention does not need to be coated with the outermost protective seam that ordinary optic fibre all has; its surrounding layer adopts polymeric optical material; surrounding layer also is the outermost layer of doubly clad optical fiber, the effect that materials such as internal cladding glass have the protection crackle to produce.During use, its surrounding layer and inner cladding are all the pump light passage, and the low refractive index dielectric (as air, water etc.) of surrounding layer and its outside constitutes the pump light waveguide, so its numerical aperture is very big, are specially adapted to the side coupling of high power pump light.Wherein the fiber cores of doubly clad optical fiber is made of inorganic optical material doping laser active materials such as quartzy, glass and crystal, and inner cladding is to be made of the inorganic optical material that can mate welding with the fibre core matrix material, and the inner cladding cross section be a circle.The refractive index maximum of fiber cores wherein, the refractive index of inner cladding equal or less times greater than the refractive index of surrounding layer.When the refractive index of inner cladding was a bit larger tham the refractive index of surrounding layer, inner cladding also had converging action, made the easier arrival fiber core of pump light, excited active medium.The exciting light that produces is constrained in the fiber cores and propagates.Therefore, use optical fiber of the present invention, when closely arranging, adopt the direct profile pump of high-power LD array, can obtain high light light conversion efficiency.So, use optical fiber of the present invention, be particularly suitable for making the fiber laser and the fiber amplifier of the high power side face-pumping of economical structure.
[description of drawings]:
Figure 1A to F, be the serial doubly clad optical fiber cross sectional representation of the embodiment of the invention 1, the inner cladding of this serial doubly clad optical fiber and fibre core are concentric circles;
Fig. 2 A to C, the special-purpose coating mould schematic cross-section of the present invention;
Fig. 3, doubly clad optical fiber surrounding layer coat synoptic diagram.
[embodiment]:
Embodiment 1:
Shown in Figure 1A to F, doubly clad optical fiber of the present invention comprises fiber cores 10, inner cladding 12, surrounding layer 14.Fiber cores 10 is made of inorganic material doping laser active materials such as glass, and its refractive index maximum is round section, and diameter is the 6-70 micron.Inner cladding 12 is to be made of the inorganic material that can mate welding with the fibre core matrix material, is round section, and diameter is the 60-600 micron, and the refractive index of inner cladding equals or less times greater than the refractive index of surrounding layer.Surrounding layer 14 cross sections can be rectangle (Figure 1A), round rectangle (Figure 1B), octagon promptly by rectangle prune residue shape (Fig. 1 C) behind four angles, patty promptly the middle part be that prune residue shape (Fig. 1 F) behind two not a half circles etc. of combination shape (Fig. 1 D), D shape (Fig. 1 E), the circle of part circular is non-circular for rectangle or square two ends.Surrounding layer and inner cladding are all the pump light passage, and surrounding layer adopts polymeric optical material, and surrounding layer also is the outermost layer of doubly clad optical fiber, the effect that materials such as internal cladding glass have the protection crackle to produce.In use, the low refractive index dielectric (as gas, water etc.) of surrounding layer and its outside constitutes the pump light waveguide, so its numerical aperture is very big, is specially adapted to the side coupling of high power pump light.
Embodiment 2:
Shown in Fig. 2 A to C, a kind ofly be specifically designed to that to make surrounding layer be the coating mould of the doubly clad optical fiber of pump light waveguide, the die matrix that has a coating hole in the middle of this mould comprises, this coating hole is infundibulate (seeing the label 13 among Fig. 3), be that the first half is a back taper, Lower Half is the uniform cross section hole, on, the cross section in following two parts hole can be following any non-circular: rectangle, round rectangle, square, rounded square, D shape, the middle part is that rectangle or square one or both ends are the combination shape of part circular, the rectangle residue shape behind one to four angle of pruning, the circle residue shape behind one or two not a half circle of pruning.This example only provides octagon and is pruned by rectangle promptly that (Fig. 2 A, patty i.e. middle part are combination shape (Fig. 2 B), three kinds of embodiment figures of round rectangle (Fig. 2 C) of part circular for rectangle or square two ends, and its complementary graph omits for residue shape behind four angles.
The process of coating of doubly clad optical fiber is seen Fig. 3, in common wire drawing machine, use the new coat polymers assembly that contains above-mentioned mould, mainly comprise cup 16, nozzle 11, with applicator die 13, when making optical fiber, with the prefabricated rods heating and the wire drawing of band covering, then, by this coating assembly, the polymkeric substance 15 in the coating assembly just is coated on naked fine 12 by the non-circular hole of applicator die 13 naked fibre from top to bottom, forms surrounding layer 14.
Claims (6)
1, a kind of surrounding layer is the doubly clad optical fiber of pump light waveguide, comprise fiber cores, covering composition, it is characterized in that described covering refers to be all the pump light passage, finishes the transmission of pump light and inner cladding and surrounding layer to the fibre core coupling jointly, be that fiber cores is followed successively by inner cladding outward, with the glass material to inner cladding protection crackle generation effect, the double surrounding layer of doing the outermost protective seam are arranged, the outside surface of surrounding layer is the interface of pump light waveguide; The cross section of surrounding layer is following any non-circular: rectangle, round rectangle, square, rounded square, D shape, middle part are that rectangle or square one or both ends are combination shape, the rectangle of part circular prune the residue shape behind one or two not a half circle of residue shape, circle behind one to four angle of pruning.
2, surrounding layer according to claim 1 is the doubly clad optical fiber of pump light waveguide, it is characterized in that surrounding layer is to be applicable to polymeric optical material surrounding layer high power pump light side coupling, cheap high-capacity optical fiber laser and fiber amplifier.
3, surrounding layer according to claim 1 and 2 is the doubly clad optical fiber of pump light waveguide, it is characterized in that fiber cores is the fiber cores that crystal or quartz, glass material doping laser active material are made.
4, surrounding layer according to claim 1 and 2 is the doubly clad optical fiber of pump light waveguide, it is characterized in that inner cladding by mating the inner cladding that the crystal of welding or quartz, the inorganic optical material of glass constitute with the fibre core matrix material, and its cross section is circular.
5, surrounding layer according to claim 1 and 2 is the doubly clad optical fiber of pump light waveguide, it is characterized in that the cladding refractive index minimum, and the refractive index of inner cladding equals or less times greater than the refractive index of surrounding layer, the refractive index maximum of fiber cores.
6, a kind ofly be specifically designed to that to make the described surrounding layer of claim 1 be the coating mould of the doubly clad optical fiber of pump light waveguide, the die matrix that has a coating hole in the middle of this mould comprises, it is characterized in that this coating hole is an infundibulate, be that the first half is a back taper, Lower Half is the uniform cross section hole, and its cross section can be following any non-circular: rectangle, round rectangle, square, rounded square, D shape, the middle part is that rectangle or square one or both ends are the combination shape of part circular, the rectangle residue shape behind one to four angle of pruning, the circle residue shape behind one or two not a half circle of pruning.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410018754 CN1238739C (en) | 2004-03-17 | 2004-03-17 | Double cladding optical fiber having external cladding as pump light guide, and its coating mould |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200410018754 CN1238739C (en) | 2004-03-17 | 2004-03-17 | Double cladding optical fiber having external cladding as pump light guide, and its coating mould |
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| CN1564032A CN1564032A (en) | 2005-01-12 |
| CN1238739C true CN1238739C (en) | 2006-01-25 |
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| CN 200410018754 Expired - Fee Related CN1238739C (en) | 2004-03-17 | 2004-03-17 | Double cladding optical fiber having external cladding as pump light guide, and its coating mould |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| EP3580590B1 (en) * | 2017-02-10 | 2022-12-21 | Heptagon Micro Optics Pte. Ltd. | Light guides and manufacture of light guides |
| CN111999795B (en) * | 2020-07-27 | 2023-08-04 | 武汉光谷航天三江激光产业技术研究院有限公司 | High-power gain optical fiber capable of simultaneously inhibiting mode instability and nonlinear effect and design method |
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