CN114488390B - Gradual change type central concave optical fiber - Google Patents
Gradual change type central concave optical fiber Download PDFInfo
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- CN114488390B CN114488390B CN202210276279.0A CN202210276279A CN114488390B CN 114488390 B CN114488390 B CN 114488390B CN 202210276279 A CN202210276279 A CN 202210276279A CN 114488390 B CN114488390 B CN 114488390B
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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
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
- G02B6/0286—Combination of graded index in the central core segment and a graded index layer external to the central core segment
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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
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03605—Highest refractive index not on central axis
- G02B6/03611—Highest index adjacent to central axis region, e.g. annular core, coaxial ring, centreline depression affecting waveguiding
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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
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
- G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
- G02B6/03655—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only arranged - + +
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
- H01S3/0672—Non-uniform radial doping
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
- H01S3/06729—Peculiar transverse fibre profile
- H01S3/06733—Fibre having more than one cladding
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
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Abstract
The embodiment of the invention discloses a gradual change type central concave optical fiber, which comprises the following components: a core arranged in the central portion; a channel cladding layer that coats the circumferential outside of the core; an inner cladding layer that covers the channel cladding layer on the outer side in the circumferential direction; and an outer cladding layer which is coated on the circumferential outer side of the inner cladding layer; wherein the refractive index of the fiber core is set to n core The refractive index of the channel cladding is set to n trench The refractive index of the inner cladding is set to n inner The refractive index of the outer cladding is set to n outer The following relation is satisfied between the refractive indices: n is n trench ＜n inner ＜n outer ≤n core The method comprises the steps of carrying out a first treatment on the surface of the The refractive index of the core is lowest at the center of the core and the refractive index of the core is at a gradually increasing potential in a radially outward direction. According to the invention, the single-mode operation of the large mode field can be still kept under the condition of larger bending radius, and the beam quality of laser is improved.
Description
Technical Field
The invention relates to the technical field of optical fibers, in particular to a gradual change type central concave optical fiber.
Background
The fiber laser is used as the representative of the third generation laser technology, and is widely applied to the fields of material processing, military science and technology, optical fiber communication and the like by the characteristics of high efficiency, good heat dissipation, high beam quality, high peak power, wide spectrum range, good compatibility, compact structure, long service life and the like, while the ytterbium-doped fiber laser has the advantages of high conversion efficiency (the loss of the laser emission quantum of 980nm pump 1080nm is only 9.26%), high beam quality output, wider gain bandwidth, good heat dissipation performance, reliable structure compact performance and the like, so that the high-power ytterbium-doped fiber laser is rapidly developed and rapidly commercialized. With the continuous increase of the output power of the fiber laser, the output power of the continuous laser can reach the magnitude of ten megawatts (the theoretical limit of the output power of the single-mode laser is 7.07 megawatts), and the output power of the pulse laser can reach the magnitude of megawatts, but the output power of the high-power laser can cause the power per unit area (i.e. the power density) in the fiber core to be too high, so that serious fiber damage, nonlinear effects such as Stimulated Brillouin Scattering (SBS), stimulated Raman Scattering (SRS) and the like are generated, and the output laser power and the beam quality of the fiber are seriously affected. With the increase of the mode field area, the probability that the fundamental mode is excited and the higher-order mode (HOM) is excited is also greatly increased, so that the output laser is not in a single mode any more, and the beam quality of the output laser is seriously affected.
The normalized frequency equation is:
where V represents the normalized frequency, λ represents the wavelength, a represents a specific constant, and NA represents the numerical aperture. Because the normalized frequency V is smaller than 2.405, single-mode operation can be ensured, and the excitation of a high-order mode can be effectively avoided by reducing the Numerical Aperture (NA) of the fiber core as much as possible while increasing the area of the mode field, but because the NA is difficult to be reduced to below 0.05 by a common quartz fiber material, and the bending loss of the fiber is aggravated when the NA is smaller than 0.05, the mode filtering treatment of a base mode and a high-order mode is difficult to be performed in a mode of bending the fiber.
There are two main types of conventional methods for achieving large mode field single mode operation: one is a fiber core control technology, which realizes single-mode operation by controlling the refractive index, doping or the number of fiber cores, and mainly comprises an ultra-low NA fiber, a part of doped fiber, a multi-core fiber, a negative refractive index fiber and the like. The other is a cladding regulation technology, which mainly adds some fluorine rods, boron rods, germanium rods or air holes into the optical fiber cladding to regulate the refractive index of the cladding so as to form some leakage channels for high-order modes, and combines bending or other filter membrane means to realize single-mode operation. The main representation optical fiber comprises chiral coupling (3C) optical fiber, leakage path optical fiber (LCF), large Pitch (LPF) optical fiber, multi-channel (MTF) optical fiber, all-solid photonic band gap (ASPBF) optical fiber, ultra-large mode area (VLMA) optical fiber and the like. The above-described method generally suppresses the nonlinear effect by increasing the effective mode field area by the number of cores, the core diameter and NA, respectively, but in addition to this, there is an increase in the effective mode field area from the structure of the core itself, that is, a core-centered depressed fiber.
In the preparation process of the optical fiber, the concentration and the distribution of the co-doped ions are adjusted, so that the uniform distribution of rare earth ions in the fiber core area can be ensured, the control of the depth and the width of the fiber core recess can be realized, and the increase of the mode field area can be realized from the structure of the fiber core. The existing fiber core concave optical fiber is step concave, and the preparation method is mainly an improved chemical vapor deposition (MCVD), the method is difficult to prepare an optical fiber preform with a large size due to the limitation of the size of a deposition sleeve, the dopant is required to be deposited at high temperature during the preparation, partial dopant is easy to volatilize during the preparation, the doping uniformity of the preform is influenced to influence the laser performance of the optical fiber, and the MCVD is easy to cause rare earth ions to cluster when preparing the high-concentration rare earth ion doped preform to influence the laser efficiency of the doped optical fiber.
Therefore, the defect of the cladding structure of the fiber core concave channel with small size and low concentration doping and the low gain effect are the problems which are urgently needed to be solved in the market of the high-power fiber laser at present.
In view of the foregoing, there is a need for a graded-index depressed center optical fiber that solves the above-mentioned problems.
Disclosure of Invention
The embodiment of the invention provides a gradual change type central concave optical fiber, which has the characteristics of large size, high concentration doping, good fiber core concave channel cladding and high gain effect, can ensure that large mode field single-mode operation can be still kept under the condition of larger bending radius, and improves the beam quality of laser.
In order to solve the technical problems, the embodiment of the invention discloses the following technical scheme:
there is provided a graded-index depressed center optical fiber, comprising:
a core arranged in the central portion;
a channel cladding layer that coats the circumferential outside of the core;
an inner cladding layer that covers the channel cladding layer on the outer side in the circumferential direction; and
an outer cladding layer which is coated on the circumferential outer side of the inner cladding layer;
wherein the refractive index of the fiber core is set to n core The refractive index of the channel cladding is set to n trench The refractive index of the inner cladding is set to n inner The refractive index of the outer cladding is set to n outer The following relation is satisfied between the refractive indices:
n trench ＜n inner ＜n outer ≤n core ；
the refractive index of the core is lowest at the center of the core and the refractive index of the core is at a gradually increasing potential in a radially outward direction.
In addition to one or more features disclosed above, or as an alternative, the matrix material of the inner cladding is fluorine doped quartz having a refractive index lower than that of pure quartz.
In addition to or in lieu of one or more of the features disclosed above, the matrix material of the overclad is pure quartz.
In addition to one or more features disclosed above, or as an alternative, the matrix material of the core is silica glass doped with activating ions.
In addition to or in lieu of one or more of the features disclosed above, the activating ion is at least one of ytterbium ion, aluminum, phosphorus, fluoride ion; the doping concentration of the activating ion is 50000ppm.
In addition to, or in lieu of, one or more of the features disclosed above, the refractive index profile of the core is in a downwardly concave parabolic configuration.
In addition to or in lieu of one or more of the features disclosed above, an inner coating layer and an outer coating layer are included.
In addition to one or more features disclosed above, or in lieu of, the average refractive index of the core and the refractive index of the channel cladding differ by-1.0 to-0.3%.
In addition to or in lieu of one or more of the features disclosed above, the difference between the refractive index of the inner cladding and the refractive index of the channel cladding is-0.12 to 0.03%.
In addition to, or in lieu of, one or more of the features disclosed above, the difference between the refractive index of the outer cladding and the refractive index of the inner cladding is-0.2 to-0.56%.
One of the above technical solutions has the following advantages or beneficial effects: because the optical fiber adopts the gradual change type central concave structure, the optical fiber can still keep large-mode-field single-mode operation under the condition of larger bending radius.
The other technical scheme has the following advantages or beneficial effects: the doping of high-concentration active ions can be carried out on the fiber core while the fiber core concave channel cladding is realized in the aspect of structure, so that the gain medium increase with the bandwidth of 10dB can be obtained with good gain effect.
The other technical scheme has the following advantages or beneficial effects: due to the larger size, the core diameter can reach 45 μm with the low numerical aperture kept between 0.06 and 0.12, thereby reducing the transmission loss.
Drawings
The technical solution and other advantageous effects of the present invention will be made apparent by the following detailed description of the specific embodiments of the present invention with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of a graded-index depressed fiber according to an embodiment of the present invention, wherein the cross section of the graded-index depressed fiber corresponds to refractive index distribution;
FIG. 2 is a refractive index profile of a graded-index depressed fiber according to embodiment 1 of the present invention;
FIG. 3 is a refractive index profile of a graded-index depressed fiber according to embodiment 2 of the present invention;
the reference numerals in the figures are as follows:
1. a graded center depressed optical fiber; 11. A fiber core;
12. a trench cladding; 13. An inner cladding;
14. and an outer cladding.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
Example 1
Referring to fig. 1, fig. 1 is a cross-sectional view of a graded-index depressed fiber 1 according to an embodiment of the present invention, in which each of the cross-sectional components is matched with a corresponding refractive index profile for ease of understanding. The graded-index central concave optical fiber 1 provided in this embodiment is to ensure that a large mode field single-mode operation can be maintained under a condition of a larger bending radius, so as to improve the beam quality of laser. The graded-index depressed center optical fiber 1 provided in the present embodiment includes:
a core 11 disposed in the center portion;
a channel cladding 12 that is coated on the circumferential outer side of the core 11;
an inner cladding layer 13 that covers the outer side of the channel cladding layer 12 in the circumferential direction; and
an outer cladding layer 14 which is wrapped around the outer periphery of the inner cladding layer 13;
wherein the refractive index of the core 11 is set to n core The refractive index of the channel cladding 12 is set to n trench The refractive index of the inner cladding 13 is n inner The refractive index of the outer cladding 14 is set to n outer The following relation is satisfied between the refractive indices:
n trench ＜n inner ＜n outer ≤n core ；
the refractive index of the core 11 is lowest at the center of the core 11, and the refractive index of the core 11 is at a gradually increasing potential in a radially outward direction.
As a non-limiting example, the matrix material of the inner cladding 13 is fluorine doped silica having a lower refractive index than pure silica, and the refractive index of the inner cladding 13 is also lower than the refractive index of the core 11.
As a further improvement, the fiber core 11 is quartz glass doped with activating ions such as ytterbium, aluminum, fluoride and the like, and the characteristic that fluoride ions are mixed with the quartz glass and the like and are extremely volatilized during high-temperature sintering, so that the fluoride ions are mixed with the quartz glass at high doping edges and low doping is caused, so that the rare earth ions of the fiber core are uniformly distributed, but the refractive index profile shows a gradually-changed downward concave parabolic structure as shown in fig. 1.
As a further improvement, the signal core is doped with 20000ppm ytterbium ions and 10000ppm aluminum ions, and also doped with fluoride ions with parabolic concentration distribution.
Fig. 2 is a refractive index profile of the graded-index depressed fiber provided in this embodiment, and thus, a graded-index depressed fiber 1 with a core diameter of 80 μm can be obtained by high-temperature fusion drawing with a sleeve of suitable size and refractive index as the core region. As a non-limiting embodiment, the absolute refractive index difference of the fiber core 11 is 0.002 at the maximum, the effective numerical aperture is 0.025, the low numerical aperture can reduce the mode in the optical fiber transmission, and the core diameter becomes thicker under the condition of stable and single mode, so that the optical signal is not easy to overflow, and the structure can keep high-efficiency operation under the large bending radius, so that the structure can effectively increase the mode field area of the optical fiber, the optical fiber has the capability of large mode field single mode operation, and the large mode field single mode operation can be kept under the condition of bending 40 mm.
As a further improvement, the matrix material of the outer cladding 14 is pure quartz.
As a further development, the matrix material of the core 11 is quartz glass doped with activating ions.
As a further improvement, the activating ion is at least one of ytterbium ion, aluminum, phosphorus and fluoride ion; the doping concentration of the activating ion is 50000ppm.
As a further improvement, an inner coating layer and an outer coating layer are also included.
As a further improvement, the difference between the average refractive index of the core 11 and the refractive index of the channel cladding 12 is-0.3%.
As a further improvement, the difference between the refractive index of the inner cladding 13 and the refractive index of the trench cladding 12 is-0.12%.
As a further improvement, the difference between the refractive index of the outer cladding 14 and the refractive index of the inner cladding 13 is-0.2%.
Example 2
Referring to fig. 1, fig. 1 is a cross-sectional view of a graded-index depressed fiber 1 according to an embodiment of the present invention, in which each of the cross-sectional components is matched with a corresponding refractive index profile for ease of understanding. The graded-index central concave optical fiber 1 provided in this embodiment is to ensure that a large mode field single-mode operation can be maintained under a condition of a larger bending radius, so as to improve the beam quality of laser. The graded-index depressed center optical fiber 1 provided in the present embodiment includes:
a core 11 disposed in the center portion;
a channel cladding 12 that is coated on the circumferential outer side of the core 11;
an inner cladding layer 13 that covers the outer side of the channel cladding layer 12 in the circumferential direction; and
an outer cladding layer 14 which is wrapped around the outer periphery of the inner cladding layer 13;
wherein the refractive index of the core 11 is set to n core The refractive index of the channel cladding 12 is set to n trench The refractive index of the inner cladding 13 is n inner The refractive index of the outer cladding 14 is set to n outer Each foldThe following relation is satisfied between the emissivity:
n trench ＜n inner ＜n outer ≤n core ；
the refractive index of the core 11 is lowest at the center of the core 11, and the refractive index of the core 11 is at a gradually increasing potential in a radially outward direction.
As a non-limiting example, the matrix material of the inner cladding 13 is fluorine doped silica having a lower refractive index than pure silica, and the refractive index of the inner cladding 13 is also lower than the refractive index of the core 11.
As a further improvement, the fiber core 11 is composed of quartz glass doped with ytterbium, aluminum and fluoride, and the characteristic that fluoride ions are mixed with the quartz glass and extremely volatilized during high-temperature sintering to cause the occurrence of internal high-doped edge low-doped in the quartz glass is utilized, so that the uniform distribution of rare earth ions of the fiber core can be realized, but the refractive index profile presents a gradually-changed downward concave parabolic structure as shown in fig. 1.
In an alternative other embodiment, the signal core is doped with 15000ppm ytterbium ions, 27000ppm aluminum ions, 15000ppm phosphorous ions, while also being doped with fluoride ions having a parabolic concentration profile.
Fig. 3 is a refractive index profile of the graded-index depressed fiber provided in this embodiment, and thus, a graded-index depressed fiber 1 with a core diameter of 30 μm can be obtained by high-temperature fusion-drawing with a sleeve of suitable size and refractive index as the core region. As a non-limiting embodiment, the absolute refractive index difference of the fiber core 11 is 0.0025 at the maximum, the effective numerical aperture is 0.035, the low numerical aperture can reduce the mode in the optical fiber transmission, and the core diameter is thickened under the condition of stable and single mode, so that the optical signal is not easy to overflow, and the optical fiber can be kept to operate efficiently under the large bending radius, so that the structure can effectively increase the mode field area of the optical fiber, the optical fiber has the capability of large mode field single mode operation, and the large mode field single mode operation can be kept under the condition of bending 35 mm.
As a further improvement, the matrix material of the outer cladding 14 is pure quartz.
As a further development, the matrix material of the core 11 is quartz glass doped with activating ions.
As a further improvement, the activating ion is at least one of ytterbium ion, aluminum, phosphorus and fluoride ion; the doping concentration of the activating ion is 50000ppm.
As a further improvement, an inner coating layer and an outer coating layer are also included.
As a further improvement, the difference between the average refractive index of the core 11 and the refractive index of the channel cladding 12 is-1.0%.
As a further improvement, the difference between the refractive index of the inner cladding 13 and the refractive index of the trench cladding 12 is 0.03%.
As a further improvement, the difference between the refractive index of the outer cladding 14 and the refractive index of the inner cladding 13 is-0.56%.
The foregoing describes in detail a graded-index depressed optical fiber provided by the embodiment of the present invention, and specific examples are applied herein to illustrate the principles and embodiments of the present invention, and the description of the foregoing examples is only for helping to understand the technical scheme and core idea of the present invention; those of ordinary skill in the art will appreciate that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. A graded-index depressed center optical fiber (1), characterized by comprising:
a core (11) arranged in the center portion;
a channel cladding (12) that is wrapped around the outer side of the fiber core (11);
an inner cladding layer (13) that is wrapped around the channel cladding layer (12) on the outer side in the circumferential direction; and
an outer cladding layer (14) that is wrapped around the outer periphery of the inner cladding layer (13);
wherein, will beThe refractive index of the fiber core (11) is set as
The refractive index of the channel cladding (12) is set to +>
The refractive index of the inner cladding (13) is set to +>
The refractive index of the outer cladding (14) is set to +.>
The following relation is satisfied between the refractive indices:
the refractive index of the core (11) is lowest at the center of the core (11), and the refractive index of the core (11) is at a gradually increasing potential in a radially outward direction;
the absolute refractive index difference of the fiber core (11) is 0.002 at maximum, the effective numerical aperture is 0.025, or the absolute refractive index difference of the fiber core (11) is 0.0025 at maximum, and the effective numerical aperture is 0.035.
2. Graded-index depressed center optical fiber (1) according to claim 1, wherein the matrix material of the inner cladding (13) is fluorine doped quartz having a lower refractive index than pure quartz.
3. A graded-index depressed center optical fiber (1) according to claim 1, wherein the matrix material of the outer cladding (14) is pure quartz.
4. A graded-index depressed center optical fiber (1) according to claim 1, wherein the matrix material of the core (11) is silica glass doped with activating ions.
5. The graded depressed center fiber (1) of claim 4, wherein the active ions are at least one of ytterbium ions, aluminum, phosphorous, fluoride ions; the doping concentration of the activating ion is 50000ppm.
6. Graded-index depressed central optical fiber (1) according to any of claims 1 to 5, characterized in that the refractive index profile of the core (11) has a downwardly depressed parabolic structure.
7. Graded depressed center optical fiber (1) according to any of claims 1 to 5, further comprising an inner coating layer and an outer coating layer.
8. The graded-index depressed center optical fiber (1) according to any one of claims 1 to 5, wherein the difference between the average refractive index of the core (11) and the refractive index of the trench cladding (12) is-1.0 to-0.3%.
9. Graded-index depressed center optical fiber (1) according to any one of claims 1 to 5, wherein the difference between the refractive index of the inner cladding (13) and the refractive index of the trench cladding (12) is-0.12 to 0.03%.
10. The graded-index depressed center optical fiber (1) according to any one of claims 1 to 5, wherein the difference between the refractive index of the outer cladding (14) and the refractive index of the inner cladding (13) is-0.2 to-0.56%.
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| CN202210276279.0A CN114488390B (en) | 2022-03-21 | 2022-03-21 | Gradual change type central concave optical fiber |
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| US6947652B2 (en) * | 2002-06-14 | 2005-09-20 | 3M Innovative Properties Company | Dual-band bend tolerant optical waveguide |
| US7400807B2 (en) * | 2005-11-03 | 2008-07-15 | Aculight Corporation | Apparatus and method for a waveguide with an index profile manifesting a central dip for better energy extraction |
| JP2014509411A (en) * | 2011-02-24 | 2014-04-17 | オーエフエス ファイテル，エルエルシー | Step index, minority mode fiber design for spatial multiplexing |
| CN105652369B (en) * | 2016-03-23 | 2019-05-21 | 中国人民解放军国防科学技术大学 | It is a kind of for exporting the large mode field gain fibre of single-mode laser |
| CN111562648B (en) * | 2020-04-30 | 2022-12-16 | 江苏永鼎光纤科技有限公司 | Large effective mode area low-loss optical fiber with optimized cladding components |
| CN114114523B (en) * | 2021-11-25 | 2023-09-19 | 长飞光纤光缆股份有限公司 | Large-mode-field-diameter single-mode optical fiber and application thereof |
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