CN115360575B - Method and device for changing refractive index distribution of gain optical fiber - Google Patents
Method and device for changing refractive index distribution of gain optical fiber Download PDFInfo
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- CN115360575B CN115360575B CN202211282089.6A CN202211282089A CN115360575B CN 115360575 B CN115360575 B CN 115360575B CN 202211282089 A CN202211282089 A CN 202211282089A CN 115360575 B CN115360575 B CN 115360575B
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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
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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
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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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- 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
- H01S3/06754—Fibre amplifiers
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Abstract
The invention relates to the technical field of laser, and provides a method and a device for changing the refractive index distribution of a gain optical fiber, wherein the method for changing the refractive index distribution of the gain optical fiber comprises the following steps: s11, performing circular axis torsion on the gain optical fiber at a certain torsion rate; and S12, spirally winding the twisted gain optical fiber on a heat radiation body. Compared with the prior art, the invention can effectively change the refractive index distribution of the gain fiber by twisting and coiling the gain fiber, and further can promote pump light transmitted in a spiral way to be emitted into the fiber core of the gain fiber, thereby improving the absorption coefficient of the pump light and the beam quality of output signal laser.
Description
Technical Field
The invention relates to the technical field of laser, in particular to a method and a device for changing the refractive index distribution of a gain optical fiber.
Background
The fiber laser has the advantages of high electro-optic conversion efficiency, good heat dissipation effect, good beam quality, high pulse energy and peak power and the like, and is widely applied to the laser processing fields of laser cutting, welding, marking, cleaning and the like. High performance, high power fiber lasers have relied heavily on the development of large mode field double clad gain fiber technology. An important performance parameter of double-clad gain fibers is the pump absorption coefficient, and the larger the absorption coefficient is, the stronger the absorption capability of the fiber per unit length to pump light is. The better pump absorption capacity is beneficial to reducing the using length of the gain fiber in the fiber laser system, thereby reducing the background loss and nonlinear effect of the fiber.
In the double-clad gain fiber, when the inner cladding has a circular structure, part of the pump light forming spiral transmission in the inner cladding cannot pass through the core of the gain fiber, so that the pump light is not absorbed, and the absorption capacity of the gain fiber to the pump light is reduced. In order to reduce the pump light forming the spiral transmission in the inner cladding of the gain fiber, different shapes and structures of the inner cladding of the gain fiber, such as hexagon, octagon, D-shape, rectangle, etc., have been designed and developed, and by breaking the circular symmetric structure of the inner cladding, the absorption capability of the double-clad gain fiber to the multimode pump light can be effectively improved.
For an actual fiber laser system, under the action of high-power pump light, the actual absorption coefficient of the gain fiber is much smaller than that under the condition of low-power pump light due to the high inverse population ratio in the gain fiber.
In addition, to ensure the beam quality of the output signal laser, a gain fiber is usually coiled in the fiber laser to filter the high-order mode signal laser.
Disclosure of Invention
Based on the method, the invention provides a method and a device for changing the refractive index distribution of a gain fiber, and particularly provides a method for changing the refractive index distribution of the gain fiber and improving the absorption of pump light by the gain fiber, a fiber amplifier and a fiber laser, which can improve the absorption coefficient of the pump light and ensure the beam quality of output signal laser.
In a first aspect, the present invention provides a method of modifying the refractive index profile of a gain optical fiber, comprising the steps of:
s11, performing circular axis torsion on the gain optical fiber at a certain torsion rate;
s12, spirally winding the twisted gain optical fiber on a heat radiation body.
In a second aspect, the present invention provides a method for improving the absorption of pump light by a gain fiber, including: the method described above is employed to change the gain fiber refractive index profile and to inject pump light into the gain fiber from at least one direction.
In a third aspect, the present invention provides an optical fiber amplifier, which adopts the above method to increase the amplification power thereof, including: the gain fiber comprises a laser light source, a pumping source, a gain fiber and a heat radiation body, wherein the pumping source is connected with the gain fiber and used for injecting signal laser into the gain fiber along the positive output direction of the signal laser, the pumping source is connected with the gain fiber and used for injecting pumping light into the gain fiber from at least one direction, and the gain fiber is coiled on the heat radiation body by adopting the method.
In a fourth aspect, the present invention provides a fibre laser comprising: the optical fiber amplifier.
The invention has the beneficial effects that:
the invention provides a method for changing the refractive index distribution of a gain optical fiber, which comprises the following steps: s11, performing circular axis torsion on the gain optical fiber at a certain torsion rate; and S12, spirally winding the twisted gain optical fiber on a heat radiation body. Compared with the prior art, the invention can effectively change the refractive index distribution of the gain optical fiber only by twisting and coiling the gain optical fiber, and the method is simple and effective.
The invention provides a method for improving the absorption of pump light by a gain optical fiber, which comprises the following steps: the method is to change the refractive index profile of the gain fiber and to inject pump light into the gain fiber from at least one direction. Compared with the prior art, the invention can promote the pump light which is spirally transmitted in the cladding to enter the fiber core of the gain fiber by twisting and coiling the gain fiber, thereby improving the absorption coefficient of the pump light and the beam quality of the output signal laser.
The invention provides an optical fiber amplifier, which adopts the method to increase the amplification power and comprises the following steps: the gain fiber is connected with the laser source and used for injecting signal laser into the gain fiber along the positive output direction of the signal laser, the pumping source is connected with the gain fiber and used for injecting pumping light into the gain fiber from at least one direction, and the gain fiber is coiled on the heat sink by adopting the method. Because the gain optical fiber adopts the method for improving the absorption of the pump light by the gain optical fiber, compared with the prior art, the amplification power of the optical fiber amplifier can be effectively increased under the condition of not increasing the power of the pump light.
In addition, the invention provides an optical fiber laser which comprises the optical fiber amplifier. Compared with the prior art, the optical fiber laser comprises the optical fiber amplifier, so that the optical fiber laser can effectively utilize pump light, and higher output power of signal laser can be obtained.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a flow chart of a method for modifying the refractive index profile of a gain fiber according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a twisted gain fiber according to an embodiment of the present invention;
fig. 3 is a structural diagram of the heat dissipation body in the embodiment of the present invention;
FIG. 4 is a structural diagram of the gain fiber spirally wound on the heat sink based on FIG. 3;
FIG. 5 is a flowchart illustrating a method for improving pump light absorption by a gain fiber according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of the optical path of a fiber laser in an embodiment of the present invention;
FIG. 7 is a schematic diagram of the optical path of another fiber laser in an embodiment of the present invention;
fig. 8 is a spectral diagram based on the pump light absorption of the example one and the comparative example one of fig. 6.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
As shown in fig. 6, the forward output direction of the signal laser beam is a direction in which the signal laser beam emitted from the laser light source 6 passes through the beam combiner 7, the gain fiber 1, and the output head 8 in this order.
In the present specification, the inner cladding refers to a cladding directly attached to and surrounding the core. In particular, in the case of a single clad fiber, the cladding is commonly referred to as the inner cladding; in the case of a double-clad or triple-clad fiber, the inner cladding refers to an inner cladding that directly adheres to and surrounds the core, and the other cladding surrounding the inner cladding is an outer cladding.
Specifically, the embodiments of the present invention will be further explained below with reference to the drawings.
The embodiment of the invention provides a method for changing the refractive index distribution of a gain optical fiber, as shown in fig. 1, comprising the following steps: s11, performing round-axis torsion on the gain optical fiber at a certain torsion rate to enable the cross section of the gain optical fiber to rotate around a central axis relatively; s12, spirally winding the twisted gain optical fiber on a heat radiation body. Compared with the prior art, the refractive index distribution of the gain fiber can be simply and effectively changed by twisting and coiling the gain fiber in the embodiment.
In this embodiment, please refer to fig. 2 for a schematic structural diagram of twisting the gain fiber.
In some embodiments, the gain fiber may be one of a single-clad fiber, a double-clad fiber or a multi-clad fiber, and in order to increase the absorption coefficient of the pump light, in this embodiment, preferably, the gain fiber is a double-clad gain fiber, that is, the gain fiber includes a core, an inner cladding and an outer cladding which are arranged from inside to outside. In order to improve the absorption of the double-clad gain fiber to the injected pump light, the diameter of a fiber core of the gain fiber is 5 to 200 mu m; the cross section of the inner cladding is in one of a hexagon shape, an octagon shape, a D shape, an oval shape, a rectangular shape or a quincunx shape. When the cross section of the inner cladding is hexagonal, octagonal, D-shaped, elliptical, rectangular or quincunx, the equivalent diameter of the inner cladding is 125 to 600 micrometers when the area of the cross section is equivalent to the area of a circle.
In the process of filtering the high-order mode signal laser, the gain fiber is generally coiled in a coiling mode with a small bending diameter so as to achieve better filtering of the high-order mode signal laser, but the absorption of the pump light by the gain fiber is further reduced, so that the signal laser output power of the actual fiber laser is influenced. In addition, the partially filtered high-order mode signal laser and the unabsorbed pump light may be absorbed by the fiber coating layer and converted into heat, which may also increase the requirement of the fiber laser on heat dissipation capability.
Therefore, in order to accurately control the refractive index distribution of the gain fiber, in this embodiment, the torsion rate of the gain fiber subjected to the circular axis torsion in step S11 is 1 to 7 °/mm, and the torsion rate is determined by the gain fiber parameters; the bending diameter of the gain optical fiber spiral winding in the step S12 is determined by the gain optical fiber parameter, and the bending diameter range is 3-30 cm.
Through experimental verification, when the twisting speed of the twisted gain optical fiber is 1 to 7 degrees per mm and the bending diameter of the spiral coil is 3 to 30 cm, a large amount of pump light transmitted in the inner cladding of the twisted gain optical fiber is emitted into the fiber core of the gain optical fiber, so that the pump light is absorbed by the fiber core of the gain optical fiber.
Specifically, in this embodiment, as shown in fig. 2, the refractive index profile n of the twisted and coiled gain fiber bt (x, y) can be expressed by the following approximate formula (1).
wherein n (x, y) is an initial refractive index distribution of the optical fiber, phi is a twist angle of the optical fiber, R is a bending radius of the gain optical fiber, x, y are an x coordinate and a y coordinate which are perpendicular to each other with a center of a cross section of the gain optical fiber as an origin, the plane formed by the x coordinate and the y coordinate is parallel to the cross section of the gain fiber, and z is a coordinate perpendicular to the origin and along the central axis direction of the gain fiber. Further, the fiber twist angle phi = (pi/180) × tr × z, where tr is the twist rate of the gain fiber in units (°/mm).
Specifically, in the step S12, the heat dissipation body is one of a cylinder or a cone to realize that the gain fiber is spirally wound upwards or downwards, where in this embodiment, the upwards or downwards refers to a direction along a central axis of the cylinder or the cone.
In order to facilitate the spiral fixation of the gain optical fiber, a spiral groove is formed in the surface of the heat radiation body, and the twisted gain optical fiber is fixed on the heat radiation body in a winding mode through the spiral groove.
In this embodiment, in order to simplify the process of manufacturing the optical fiber laser, preferably, as shown in fig. 3, the heat dissipation body is a cylinder 3, the diameter of the cylinder 3 is 3 to 30 cm, the interior of the cylinder 3 is a hollow structure 4, and the heat dissipation efficiency of the cylinder 3 can be improved; the cylindrical surface of the cylinder 3 is provided with a spiral groove 2; as shown in fig. 4, the gain fiber 1 is fixed on the cylinder 3 through the spiral groove, so that the gain fiber can be effectively prevented from being randomly wound in a staggered manner. Wherein, the edges forming the two sides of the spiral groove are arranged on a fillet (not shown) to ensure that the gain optical fiber is scratched or pulled in the winding process.
In order to effectively fix the gain optical fiber and improve the heat dissipation capability of the gain optical fiber, the spiral groove 2 may be filled with silica gel. In addition, in the present embodiment, by winding the gain fiber 1 around the cylinder 3, the height of the cylinder 3 can be fully utilized, and the volume of the optical path system in the fiber laser can be reduced.
In this embodiment, the cylinder 3 is made of a metal material with good thermal conductivity, such as red copper, aluminum alloy, and silver-plated metal.
In addition, an embodiment of the present invention provides a method for improving absorption of pump light by a gain fiber, as shown in fig. 5, including: the method for changing the refractive index profile of the gain fiber described in this embodiment is adopted to change the refractive index profile of the gain fiber, and step S13, pump light is injected into the gain fiber from at least one direction. Compared with the prior art, in the embodiment, the refractive index distribution of the gain fiber 1 is changed by twisting and coiling the gain fiber 1, so that the pump light which is spirally transmitted along the cladding of the gain fiber 1 is emitted into the fiber core of the gain fiber 1, the absorption of the spirally transmitted pump light is improved, and the absorption of the pump light and the beam quality of the output signal laser are improved.
In this embodiment, in step S13, the pump light is injected into the gain fiber from at least one direction, and it may be understood that the pump light is injected into the gain fiber along a reverse output direction of the signal laser along a forward output direction of the signal laser, or the pump light is injected into the gain fiber along the forward output direction of the signal laser, that is, the pump light is injected into the gain fiber from an end face of the gain fiber. Further, the pump light may also be injected from the sidewall of the gain fiber.
In addition, an embodiment of the present invention further provides an optical fiber amplifier, including: the gain fiber is coiled on the heat radiator by adopting the method for improving the absorption of the pump light by the gain fiber.
For the fiber laser, pump light may be injected from the end face or the side wall of the gain fiber as required. When the pump light is injected from the end face of the gain fiber, the injection of the pump light into the gain fiber may be forward pumping, backward pumping, or bidirectional pumping. As shown in fig. 6, in the forward pumping, a pumping output end of the pumping source 5 is connected to a pumping input end of the beam combiner 7, signal laser emitted by the laser source 6 is connected to an input end of the beam combiner 7, an output end of the beam combiner 7 is connected to an input end of the gain fiber 1, an output end of the gain fiber 1 is connected to an input end of the output head 8, and an output end of the output end is used for emitting the signal laser. As shown in fig. 7, in the reverse pumping, a pumping output end of the pumping source 5' is connected to a pumping input end of a beam combiner 7', signal laser emitted by the laser source 6' is connected to an input end of the gain fiber 1', an output end of the gain fiber 1' is connected to an input end of the beam combiner 7', an output end of the beam combiner 7' is connected to an input end of the output head 8', and an output end of the output head 8' is used for emitting the signal laser. It should be noted that the input end and the output end are for inputting and outputting signal laser.
In some embodiments, the laser light source may be any one of a laser light source for emitting continuous signal laser light, a laser light source for emitting pulsed signal laser light, or a laser light source for emitting quasi-continuous signal laser light. According to the laser processing requirement, different laser light sources can be selected.
Further, in order to more objectively understand whether the method for improving the absorption of the pump light by the gain fiber adopted in the embodiment has a significant effect, the embodiment one and the comparative example are adopted in the invention for comparative analysis.
The first embodiment and the first comparative example each employ the optical fiber amplifier as shown in fig. 6, except that the gain fiber of the first embodiment is twisted along its circular axis at a certain twist rate, and the twisted gain fiber is twisted; while comparative example one only helically winds the gain fiber. The first example and the first comparative example were tested to obtain a spectrum, as shown in fig. 8. It can be seen from fig. 8 that the absorption of the pump light of this embodiment is significantly higher than that of comparative example one, and the pump absorption coefficients at 915nm and 975nm in fig. 8 are improved by 0.2-0.5dB/m relative to that of comparative example one.
In addition, the embodiment of the invention also provides an optical fiber laser which comprises the optical fiber amplifier provided by the embodiment.
To sum up, an embodiment of the present invention provides a method for improving absorption of pump light by a gain fiber, including the steps of: s11, performing circular axis torsion on the gain optical fiber at a certain torsion rate; and S12, spirally winding the twisted gain optical fiber on a heat radiation body. Compared with the prior art, the method can effectively change the refractive index of the gain optical fiber only by twisting and coiling the gain optical fiber, and is simple and effective.
The embodiment of the invention also provides a method for improving the absorption of the pump light by the gain optical fiber, which comprises the following steps: the method for changing the refractive index distribution of the gain fiber and the method for injecting the pump light into the gain fiber from at least one direction are adopted. Compared with the prior art, the invention can promote the pump light transmitted in a spiral way to be emitted into the fiber core of the gain fiber by twisting and coiling the gain fiber, thereby improving the absorption coefficient of the pump light and the beam quality of the output signal laser.
The embodiment of the invention also provides an optical fiber amplifier, which adopts the method of the embodiment of the invention to increase the amplification power and comprises the following steps: the gain fiber comprises a laser light source, a pumping source, a gain fiber and a heat radiation body, wherein the laser light source is connected with the gain fiber and used for injecting signal laser into the gain fiber along the positive output direction of the signal laser, the pumping source is connected with the gain fiber and used for injecting pumping light into the gain fiber from at least one direction, and the gain fiber is coiled on the heat radiation body by adopting the method of the embodiment. Because the gain fiber adopts the method for improving the absorption of the pump light by the gain fiber, compared with the prior art, the amplification power of the fiber amplifier can be effectively increased under the condition of not increasing the power of the pump light.
Finally, an embodiment of the present invention provides an optical fiber laser, including: the optical fiber amplifier of the embodiment of the invention. Compared with the prior art, the optical fiber laser comprises the optical fiber amplifier, so that the optical fiber laser can effectively utilize pump light, and higher output power of signal laser can be obtained.
The method for changing the refractive index distribution of the gain fiber and improving the absorption of the pump light by the gain fiber, the fiber amplifier and the fiber laser provided by the embodiment of the invention are described in detail above, a specific example is applied in the text to explain the principle and the implementation mode of the invention, and the description of the above embodiment is only used to help understanding the method and the core idea of the invention; meanwhile, for those skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed, and in summary, the content of the present specification should not be construed as limiting the present invention.
Claims (10)
1. A method of modifying the refractive index profile of a gain optical fiber, said gain optical fiber comprising an inside-out core, an inner cladding and an outer cladding, the method comprising the steps of:
s11, performing circular axis torsion on the gain optical fiber at a certain torsion rate;
and S12, spirally coiling the twisted gain optical fiber on a heat radiation body to improve the absorption coefficient of the pump light.
2. The method of claim 1, wherein the twisting rate of the gain fiber in the step S11 is 1 to 7 °/mm, and the twisting rate is determined by the gain fiber parameters;
the bending diameter of the spiral winding of the gain optical fiber in the step S12 is determined by the gain optical fiber parameter, and the bending diameter range is 3-30 cm.
3. The method of changing the refractive index profile of a gain optical fiber according to claim 2, wherein the heat sink is one of a cylinder and a cone.
4. The method of changing the refractive index profile of a gain fiber according to claim 1,
the refractive index profile nbt (x, y) of the gain fiber after the change satisfies formula (1),
the n (x, y) is the initial refractive index distribution of the optical fiber, phi is the torsion angle of the optical fiber, R is the bending radius of the gain optical fiber, x and y are an x coordinate and a y coordinate which take the center of the cross section of the gain optical fiber as an origin and are perpendicular to each other, and a plane formed by the x coordinate and the y coordinate is parallel to the cross section of the gain optical fiber.
5. The method for changing the refractive index distribution of the gain optical fiber according to claim 3, wherein a spiral groove is formed on the surface of the heat sink, and the twisted gain optical fiber is fixed on the heat sink by winding the spiral groove.
6. The method of changing the refractive index profile of a gain optical fiber according to any one of claims 1 to 5, wherein the gain optical fiber comprises a core, an inner cladding and an outer cladding disposed from the inside to the outside, the inner cladding having a cross-sectional shape of one of a hexagon, an octagon, a "D" shape, an ellipse, a rectangle or a quincunx shape, the inner cladding having an equivalent diameter of 125 to 600 μm, and the core having a diameter of 5 to 200 μm.
7. A method for increasing the absorption of pump light by a gain fiber, comprising: use of the method of any of claims 1-6 to modify the gain fiber refractive index profile and to inject pump light into the gain fiber from at least one direction.
8. An optical fiber amplifier employing the method of claim 7 to increase its amplification power, comprising: the gain fiber comprises a laser light source, a pumping source, a gain fiber and a heat radiation body, wherein the laser light source is connected with the gain fiber and used for injecting signal laser into the gain fiber along the positive output direction of the signal laser, the pumping source is connected with the gain fiber and used for injecting pumping light into the gain fiber from at least one direction, and the gain fiber is coiled on the heat radiation body by adopting the method of claim 7.
9. The optical fiber amplifier according to claim 8, wherein the laser light source may be any one of a laser light source for emitting continuous signal laser light, a laser light source for emitting pulse signal laser light, or a laser light source for emitting quasi-continuous signal laser light.
10. A fibre laser comprising a fibre amplifier as claimed in claim 8 or 9.
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| GB0314817D0 (en) * | 2003-06-25 | 2003-07-30 | Southampton Photonics Ltd | Apparatus for providing optical radiation |
| US7983312B2 (en) * | 2007-08-09 | 2011-07-19 | Raytheon Company | Method and apparatus for generation and amplification of light in a semi-guiding high aspect ratio core fiber |
| US8854713B2 (en) * | 2009-05-06 | 2014-10-07 | Sandia Corporation | Power selective optical filter devices and optical systems using same |
| US20170235049A1 (en) * | 2016-02-12 | 2017-08-17 | Institut National D'optique | Optical fiber assembly with enhanced filtering of higher-order modes |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1873874A2 (en) * | 1999-04-30 | 2008-01-02 | SPI Lasers UK Limited | An optical fibre arrangement |
| CN110911952A (en) * | 2019-12-20 | 2020-03-24 | 成都翱翔拓创光电科技合伙企业(有限合伙) | Multi-optical-fiber stress traction torsion beam combining device and manufacturing method thereof |
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| CN115360575A (en) | 2022-11-18 |
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