CN113140951B - Annular laser output device - Google Patents
Annular laser output device Download PDFInfo
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- CN113140951B CN113140951B CN202110366340.6A CN202110366340A CN113140951B CN 113140951 B CN113140951 B CN 113140951B CN 202110366340 A CN202110366340 A CN 202110366340A CN 113140951 B CN113140951 B CN 113140951B
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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
- H01S3/06791—Fibre ring lasers
Abstract
The invention discloses an annular laser output device which comprises a packaging shell, a filler, an input optical fiber and an output optical fiber, wherein the input optical fiber is connected with the output optical fiber in a matching way and is arranged in the packaging shell, and the filler fills the region between the packaging shell and the input optical fiber as well as the region between the packaging shell and the output optical fiber; the output optical fiber comprises an output fiber core, an output inner cladding and an output outer cladding, the output inner cladding and the output outer cladding are sequentially sleeved on the periphery of the output fiber core, the taper end of the output optical fiber is coupled and welded with one end of the input optical fiber, and the refractive index of the output inner cladding is larger than that of the output fiber core and that of the output outer cladding. The invention adopts the matching coupling mode of the input optical fiber and the output optical fiber of the double-cladding structure, and the refractive index of the output inner cladding is larger than that of the output fiber core and the output outer cladding, so that the device adopts the full-fiber coupling structure to output the annular light beam without central energy, and realizes the high-efficiency conversion of the high-energy solid light beam to the annular light beam.
Description
Technical Field
The invention relates to the field of laser devices, in particular to an annular laser output device.
Background
With the maturity of fiber lasers made in China of 500-6000W, the fiber lasers become mainstream lasers used by domestic industrial laser cutting machines at present. However, when the conventional beam laser is used for cutting, if the thickness of the cutting plate is large, the middle-lower part of the front edge of the cutting seam is easily overheated, so that the cutting defect is caused, and the flatness of the cut end surface is poor. In order to solve the problem that traditional beam laser exists in the cutting process, annular beam is selected for use at present more, because annular facula center energy density is lower, not only can improve the cutting speed to the sheet metal, can make the cutting end face more exquisite when the cutting to the thick plate moreover, the roughness is lower, demonstrates better terminal surface roughness, can promote high energy fiber laser's comprehensive cutting ability. However, if the cutting adaptability of the annular light beam to plates with different thicknesses needs to be further improved, the annular light beam needs to be capable of being controllably changed and adjusted.
Currently, the methods for realizing variable ring beams are mainly divided into two types: one solution adopts a lens group to realize the beam change, taking the invention solution of patent No. CN108931855 as an example, the device comprises a focusing lens, a tubular reflector and a collimating lens, the structure can realize the arbitrary change of the inner diameter and the outer diameter of the annular beam, but adopts a space optical structure to shape the laser beam, the requirement on the matching precision between devices is very high, the device is not beneficial to the industrial integration of the device, the mechanical structure stability is poor, and the device has great limitation in large-scale industrial application. The other scheme is to use a special optical waveguide structure for beam shaping, taking patent number CN210465873U as an example, and adopting a structure that an input optical fiber is welded with an output optical fiber and then tapered to match to realize output of point annular light spots; the transmission structure is stable and reliable, but the existence of the central energy of the output light spot cannot be avoided, and the existence of the concentrated central energy light spot enables the laser to generate raised grains on a cutting section in the process of cutting a thick plate, so that the problems of increased roughness and reduced cutting quality are caused. It is desirable to provide a new ring laser output device that solves the above-mentioned problems of the prior art.
Disclosure of Invention
The invention aims to provide an annular laser output device, which is used for solving the problem that the flatness of the cutting section of laser is poor due to the central energy of an annular light beam generated by an optical fiber based on an all-fiber coupling structure in the prior art.
In order to solve the technical problem, the invention provides an annular laser output device which comprises a packaging shell, a filler, an input optical fiber and an output optical fiber, wherein the input optical fiber is connected with the output optical fiber in a matching way and is arranged in the packaging shell, and the filler fills the area among the packaging shell, the input optical fiber and the output optical fiber; the input optical fiber comprises an input fiber core and an input cladding, the input cladding is sleeved on the periphery of the input fiber core, and the refractive index of the input fiber core is greater than that of the input cladding; the output optical fiber comprises an output fiber core, an output inner cladding and an output outer cladding, the output inner cladding and the output outer cladding are sequentially sleeved on the periphery of the output fiber core, one end of the output optical fiber is of a tapered structure and is in coupling fusion joint with one end of the input optical fiber, and the refractive index of the output inner cladding is larger than that of the output fiber core and is larger than that of the output outer cladding.
Preferably, the numerical aperture of the input core is recorded as NA1 and satisfies 0.03-1 NA 1-1; the radius of the input fiber core is recorded as r1, and the radius is more than 0 and less than or equal to r1 and less than or equal to 25 mu m; the radius of the input cladding is recorded as R1, and satisfies 52.5 ≦ R1 ≦ 200 μm.
Preferably, the numerical aperture formed by the output inner cladding and the output outer cladding is represented as NA2, the numerical aperture formed by the output core and the output inner cladding is represented as NA3, and the numerical aperture satisfies the conditions that NA2 is not less than 0.03 and not more than 1 and NA3 is not less than NA 2; the radial length of the tapered region of the output optical fiber after tapering is recorded as L, and L is more than or equal to 5mm and less than or equal to 500 mm.
Preferably, the radius of the output fiber core is recorded as r2, and satisfies 0< r2 ≤ 100 μm, and the radius of the output fiber core is matched with the size of the central dark spot of the annular light beam generated by the annular laser output device; the cross-sectional thickness of the output inner cladding is recorded as T2, r1 is more than or equal to T2 is more than or equal to 200 mu m, and the cross-sectional thickness of the output inner cladding is matched with the width of the annular light beam generated by the annular laser output device; the outer radius of the output outer cladding is recorded as R2, and R2+ T2 is less than or equal to R2 is less than or equal to 500 mu m.
When the refractive index of the output fiber core is 1, the output fiber core is an air medium, the output fiber is a hollow fiber with a double-layer cladding structure, and the coupling fusion welding step of the input fiber and the output fiber is as follows: tapering one end of the output optical fiber in equal proportion to uniformly reduce the hollow hole on the output optical fiber to be closed, cutting the tapered end of the output optical fiber and coupling and welding the tapered end with the input optical fiber; and at the coupling fusion joint, the hollow hole on the end face of the output optical fiber is completely closed, the radius of the end face of the output inner cladding is recorded as r3, and r3 is more than or equal to r 1.
Further, when the output optical fiber is a hollow optical fiber, the following relation is satisfied:
wherein L is 0 For the radial length of the taper region of the output fiber before tapering, the output envelopeThe end radius of the layer is denoted as R3.
When the refractive index of the output fiber core is greater than 1, the output fiber core is a solid medium, the output fiber is a solid fiber with a double-layer cladding structure, and the coupling fusion welding step of the input fiber and the output fiber is as follows: tapering one end of the output optical fiber in equal proportion to uniformly reduce the output fiber core, the output inner cladding and the output outer cladding, cutting the tapered end of the output optical fiber and coupling and welding the tapered end with the input optical fiber; at the coupling welding position, the radius of the end face of the output fiber core is recorded as r3', the thickness of the end face of the output inner cladding is recorded as T3, and r3' + T3 is more than or equal to r1 and r3 '; the end face radius of the output outer cladding layer at the coupling welding position is recorded as R3, and R3' is more than or equal to R3 and less than or equal to 400 mu m.
Further, when the output optical fiber is a solid core optical fiber, the following relationship is satisfied:
wherein L is 0 Is the radial length of the tapered region of the output fiber before tapering.
Preferably, the packaging shell is a metal shell with a protection function, and the filler is a polymer and is used for fixing the input optical fiber and the output optical fiber and protecting the surfaces of the input optical fiber and the output optical fiber from being affected by moist gas and external force friction.
The beneficial effects of the invention are: the invention provides an annular laser output device which is different from the prior art, the refractive index of an output inner cladding is limited to be larger than the refractive indexes of an output fiber core and an output outer cladding by a mode that an input fiber is coupled with an output fiber of a double-cladding structure in a matching mode, so that the formed all-fiber coupling structure can output annular beams without central energy, the stability of the whole structure of the device and the flatness of a cut section are improved, and the high-efficiency conversion of high-energy solid beams to the annular beams is realized.
Drawings
Fig. 1 is a schematic structural view of a ring laser output device in embodiment 1 of the present invention;
FIG. 2a is a schematic cross-sectional view of an output optical fiber in example 1 of the present invention, and FIG. 2b is a schematic cross-sectional refractive index of the output optical fiber in example 1 of the present invention;
fig. 3a is a schematic diagram of an annular light spot output by an annular laser output device in embodiment 1 of the present invention, and fig. 3b is a light field intensity distribution diagram presented by the annular laser output device in embodiment 1 of the present invention in a process of outputting a light beam;
FIG. 4 is a schematic structural view of a ring laser output device in embodiment 2 of the present invention;
FIG. 5a is a schematic cross-sectional view of an output optical fiber in example 2 of the present invention, and FIG. 5b is a schematic cross-sectional refractive index of the output optical fiber in example 2 of the present invention;
fig. 6a is a schematic diagram of an annular light spot output by an annular laser output device in embodiment 2 of the present invention, and fig. 6b is a light field intensity distribution diagram presented by the annular laser output device in embodiment 2 of the present invention in a process of outputting a light beam.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to 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 based on the embodiments of the present invention without any creative effort, fall within the protection scope of the present invention.
The annular laser output device comprises a packaging shell, filler, an input optical fiber and an output optical fiber, wherein the input optical fiber is connected with the output optical fiber in a matching way and is arranged in the packaging shell, and the filler fills the region between the packaging shell and the input optical fiber as well as the region between the packaging shell and the output optical fiber; the input optical fiber comprises an input fiber core and an input cladding, the input cladding is sleeved on the periphery of the input fiber core, the refractive index of the input fiber core is larger than that of the input cladding, and a solid light beam is generated at the input optical fiber; output optical fiber is including exporting the fibre core, output inner cladding and output surrounding layer, output inner cladding, output surrounding layer overlaps in proper order and locates that output fibre core is peripheral, output optical fiber one end for the structure of tapering and with input optical fiber one end coupling butt fusion, the refracting index of output inner cladding is greater than the refracting index of output fibre core and is greater than the refracting index of output surrounding layer, because the refracting index of the output inner cladding in will exporting optical fiber is the biggest, just can export annular beam and do not have central energy. The parameter conditions to be satisfied by the above components are specifically as follows.
Specifically, the numerical aperture of the input fiber core is marked as NA1, and the NA1 is more than or equal to 0.03 and less than or equal to 1; the radius of the input fiber core is recorded as r1, and the radius is more than 0 and less than or equal to r1 and less than or equal to 25 mu m; the radius of the input cladding is recorded as R1, and satisfies 52.5 ≦ R1 ≦ 200 μm.
Specifically, the numerical aperture formed by the output inner cladding and the output outer cladding is recorded as NA2, the numerical aperture formed by the output core and the output inner cladding is recorded as NA3, and NA2 is more than or equal to 0.03 and less than or equal to 1, and NA2 is more than or equal to NA 3; the radial length of the tapered region of the output optical fiber after tapering is recorded as L, and L is more than or equal to 5mm and less than or equal to 500 mm.
Specifically, the radius of the output fiber core is recorded as r2, and meets the condition that r2 is more than 0 and less than or equal to 100 mu m, and the radius of the output fiber core is matched with the size of a central dark spot of the annular light beam generated by the annular laser output device; the cross-sectional thickness of the output inner cladding is recorded as T2, r1 is more than or equal to T2 is more than or equal to 200 mu m, and the cross-sectional thickness of the output inner cladding is matched with the width of the annular light beam generated by the annular laser output device; the outer radius of the output outer cladding is recorded as R2, and R2+ T2 is less than or equal to R2 is less than or equal to 500 mu m.
Since the refractive index of the output core is different between the case where the output fiber is a solid core and the case where the refractive index of the output core is 1 or more, the parameter limitations in these cases will be described below.
When the refractive index of the output fiber core is 1, the output fiber core is an air medium, the output fiber is a hollow fiber with a double-layer cladding structure, and the coupling fusion welding step of the input fiber and the output fiber is as follows: performing equal-proportion tapering on one end of the output optical fiber to uniformly reduce the hollow hole on the output optical fiber to be closed, cutting the tapered end of the output optical fiber and coupling and welding the tapered end with the input optical fiber; and at the coupling fusion joint, the hollow hole on the end face of the output optical fiber is completely closed, the radius of the end face of the output inner cladding is recorded as r3, and r3 is more than or equal to r 1. Specifically, when the output optical fiber is a hollow optical fiber, the following relationship is satisfied:
in the above formulae (1) and (2), L 0 The end radius of the output outer cladding is denoted as R3 for the radial length of the tapered region of the output fiber before tapering. Conversion efficiency eta of solid beam into annular beam under condition of hollow output optical fiber>95％。
When the refractive index of the output fiber core is larger than 1, the output fiber core is a solid medium, the output fiber is a solid fiber with a double-layer cladding structure, and the coupling fusion welding step of the input fiber and the output fiber is as follows: performing equal-proportion tapering on one end of the output optical fiber to uniformly reduce the output fiber core, the output inner cladding and the output outer cladding, cutting the tapered end of the output optical fiber and coupling and welding the tapered end with the input optical fiber; at the coupling welding position, the radius of the end face of the output fiber core is recorded as r3', the thickness of the end face of the output inner cladding is recorded as T3, and r3' + T3 is more than or equal to r1 and r3 '; the end face radius of the output outer cladding layer at the coupling welding position is recorded as R3, and R3' is more than or equal to R3 and less than or equal to 400 mu m.
Further, when the output optical fiber is a solid core optical fiber, the following relationship is satisfied:
in the above formulae (3) to (5), L 0 Is the radial length of the tapered region of the output fiber before tapering. In the case of a solid output fiber, the conversion efficiency η of a solid beam into an annular beam is related to the cone length L and the cone apex dimensions r3 and T3 by the relationship:
in the invention, the packaging shell is preferably a metal shell with a protection function, the filler is preferably a polymer material such as acrylate, silicone rubber and nylon, and the filler is used for fixing the input optical fiber and the output optical fiber and protecting the surfaces of the input optical fiber and the output optical fiber from the influence of moist gas and external force friction, so that the internal optical fiber coupling structure has better stability and durability, and the materials of the specific packaging shell and the filler can be adaptively selected according to actual requirements, without limitation. The preparation steps of the annular laser output device comprise optical fiber design, optical fiber preparation, tapering, cutting and welding and packaging.
In the optical fiber design process, because one end of the input optical fiber, which is far away from the output optical fiber, needs to be connected with the laser tail fiber, the optical fiber design needs to design the input optical fiber matched with the mode field according to the laser tail fiber; according to the spot size of the required annular laser beam, the hollow core hole radius R2, the high-refractive-index thickness T2 and the cladding outer diameter R2 of the output optical fiber are designed; and then, a proper tapered region length L and an output fiber core radius R3 of the tapered region end face are designed according to the input fiber core radius R1, the input cladding outer side radius R1 and the output fiber size, the output inner cladding thickness T3 and the output outer cladding outer diameter R3, and related parameters also need to satisfy the parameter limiting conditions, which are not described herein again.
After the input optical fiber and the output optical fiber are designed in size, the required input optical fiber and output optical fiber are prepared by MCVD technology and wire drawing technology, and then the prepared output optical fiber is tapered, preferably LZM100 optical fiber processing equipment is used for implementing the tapering step. The taper size of the output optical fiber is checked after the tapering is finished, a proper position is selected for cutting, the input optical fiber and the taper end face of the output optical fiber are welded by the LZM100 equipment, a reasonable welding model and welding parameters are set according to actual requirements, the welding loss is reduced to the minimum, and no limitation is made here.
The following explains the embodiments and effects of the ring laser output device according to the present invention by specific examples.
Example 1
Referring to fig. 1, 2a and 2b, 110 is a package, 120 is a filler, 130 is an input fiber, 131 is an input core, 132 is an input cladding, 140 is an output fiber, 141 is an output core, 142 is an output inner cladding, and 143 is an output outer cladding. In the present example, the numerical aperture NA1 of the input fiber is 0.06, the input core radius R1 is 25 μm, the input cladding radius R1 is 200 μm, and the input laser light to the input fiber is a gaussian beam; the refractive index n1 of the output fiber core is 1, namely the fiber core is air, the output optical fiber is a hollow optical fiber with a high-refractive-index ring-core structure, the ring-core structure is an output inner cladding, and the refractive index of the output inner cladding is larger than that of the output outer cladding; the numerical aperture NA2 formed by the high-refractive-index output inner cladding and the outer cladding is 0.1, and the numerical aperture NA3 formed by the high-refractive-index output inner cladding and the hollow core is 1.1.
The hollow radius R2 of the output core is 20 μm, the output inner cladding thickness T2 is 15 μm, and the outer radius R2 of the output outer cladding is 200 μm; the hollow diameter of the end face of the output tapered optical fiber at the welding position is 0, the output inner cladding with high refractive index is of a solid core structure with high refractive index, the end face radius R3 of the output inner cladding at the coupling welding position is 25 mu m, the length L of the taper region of the output optical fiber is 20mm, the end face radius R3 of the output outer cladding at the coupling welding position is 142.9 mu m, and the original length L of the taper region can be calculated by the relational expressions (1) and (2) 0 ＝18.8mm。
At the moment, the tapering process is different in the five processes of optical fiber design, optical fiber preparation, tapering, cutting and welding and packaging, one end of a hollow output optical fiber needs to be sealed before tapering, then the sealing end of the output optical fiber is tapered by utilizing LZM, air pressure treatment is slowly carried out at the non-sealing end in the tapering process, the pressure is well controlled, the hollow hole is uniformly contracted to be closed, and the situation that the hollow hole is rapidly collapsed or is difficult to close is avoided; therefore, the hollow core hole at the cutting and welding position is in a closed state, and the radius of the output inner cladding of the high-refractive-index solid core structure is not less than that of the input fiber core, namely r3 is not less than r 1.
Referring to fig. 3a and fig. 3b, in the present embodiment, a dark spot center diameter of the output ring-shaped light beam near-field light spot is denoted by D, where D is 40 μm, and a width of the ring-shaped light spot is denoted by T, where T is 15 μm; as can be clearly seen from fig. 3a, the light spot output by the device has energy distribution only in the annular region, and the central region has no energy distribution; and the z axis in fig. 3b is the extending direction of the light beam output, and the x-y plane is the cross-sectional plane of the output light spot, it can be seen that the energy characterization effects obtained in fig. 3a and 3b are mutually verified, the energy convergence phenomenon only occurs at the extending end, and the light beam energy in other regions can be in a better annular distribution state, so as to avoid the distribution of the central energy. On the other hand, the conversion efficiency obtained through simulation experiments is 99.8%, and the fact that the loss of the all-fiber coupling structure is very small is proved, the solid light beams can be efficiently converted into the annular light beams, the output light beams cannot generate raised grains in the actual cutting process, and the flatness of the cut sections is remarkably improved.
Example 2
Referring to fig. 4, 5a and 5b, 210 is a package, 220 is a filler, 230 is an input fiber, 231 is an input core, 232 is an input cladding, 240 is an output fiber, 241 is an output core, 242 is an output inner cladding, and 243 is an output outer cladding. In the present embodiment, the numerical aperture NA1 of the input fiber is 0.12, the input core radius R1 is 10 μm, the input cladding radius R1 is 200 μm, and the input laser light to the input fiber is a gaussian beam; the refractive index n1 of the output fiber core is more than 1, namely the fiber core is a solid core, the output optical fiber is a solid core optical fiber with a high-refractive-index output inner cladding, and the refractive index of the output inner cladding is larger than that of the output outer cladding; the numerical aperture NA2 formed by the output inner cladding and the outer cladding with high refractive index is 0.5, and the numerical aperture NA3 formed by the output inner cladding and the output core with high refractive index is 1.05.
The solid core radius R2 of the output core is 15 μm, the output inner cladding thickness T2 is 30 μm, and the outer radius R2 of the output outer cladding is 300 μm; in this case, the end radius R3'+ T3 of the output inner cladding at the coupling fusion splice is 10 μm, the taper length L of the output optical fiber is 100mm, and can be calculated from the above-mentioned relational expressions (3) to (5), and the outer radius R3 of the output outer cladding at the coupling fusion splice is 142.9 μm, the output core radius R3' is 3.3 μm, and the original length L of the taper region is 3.3 μm 0 ＝27.6mm。
Referring to fig. 6a and fig. 6b, in the present embodiment, a dark spot center diameter of the output ring-shaped light beam near-field light spot is denoted by D, where D is 30 μm, and a width of the ring-shaped light spot is denoted by T, where T is 30 μm; as can be clearly seen from fig. 6a, the light spot output by the device has energy distribution only in the annular region, and the central region has no energy distribution; and the z axis in fig. 6b is the extending direction of the light beam output, and the x-y plane is the cross-sectional plane of the output light spot, so that it can be seen that the energy characterization effects obtained in fig. 6a and 6b are mutually verified, and the energy convergence phenomenon only occurs at the extending end, and the light beam energy in other regions can be in a better annular distribution state, so as to avoid the distribution of central energy. On the other hand, the conversion efficiency obtained through simulation experiments is 99.7%, and the fact that the loss of the all-fiber coupling structure is small is proved, the solid light beam can be efficiently converted into the annular light beam, the output light beam does not generate raised grains in the actual cutting process, and the flatness of the cut section is remarkably improved.
Embodiments 1 and 2 respectively represent two situations of a hollow core and a solid core of the annular laser output device, and it can be seen that, no matter in the case of the hollow core or the solid core, the output light beam effects are the same, a better annular distribution state can be presented, and the distribution of central energy is avoided, so that the problem of raised grains in the cutting process can be solved, and the flatness of a cut section is remarkably improved; meanwhile, the solid light beam can be efficiently converted into the annular light beam by utilizing the all-fiber coupling structure, and the loss in the conversion process is well controlled. In addition, the annular laser output device adopts an all-fiber coupling structure, so that the device has higher structural stability and smaller integration space, and can well perform adaptive adjustment on fiber size design parameters according to the output requirements of different annular beams, thereby being more beneficial to industrial integration application.
The invention provides an annular laser output device which is different from the prior art, the refractive index of an output inner cladding is limited to be larger than the refractive indexes of an output fiber core and an output outer cladding by a mode that an input fiber is coupled with an output fiber of a double-cladding structure in a matching mode, so that the formed all-fiber coupling structure can output annular beams without central energy, the stability of the whole structure of the device and the flatness of a cut section are improved, and the high-efficiency conversion of high-energy solid beams to the annular beams is realized.
It should be noted that the above embodiments belong to the same inventive concept, and the description of each embodiment has a different emphasis, and reference may be made to the description in other embodiments where the description in individual embodiments is not detailed.
The above-mentioned embodiments only express the embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (5)
1. The annular laser output device is characterized by comprising a packaging shell, filler, an input optical fiber and an output optical fiber, wherein the input optical fiber is connected with the output optical fiber in a matching way and is arranged in the packaging shell, and the filler fills the areas among the packaging shell, the input optical fiber and the output optical fiber;
the input optical fiber comprises an input fiber core and an input cladding, the input cladding is sleeved on the periphery of the input fiber core, and the refractive index of the input fiber core is greater than that of the input cladding;
the output optical fiber comprises an output fiber core, an output inner cladding and an output outer cladding, the output inner cladding and the output outer cladding are sequentially sleeved on the periphery of the output fiber core, one end of the output optical fiber is of a tapered structure and is in coupling fusion with one end of the input optical fiber, and the refractive index of the output inner cladding is larger than that of the output fiber core and larger than that of the output outer cladding;
when the refractive index of the output fiber core is 1, the output fiber core is an air medium, the output fiber is a hollow fiber with a double-layer cladding structure, and the coupling fusion welding step of the input fiber and the output fiber is as follows: performing equal-proportion tapering on one end of the output optical fiber to uniformly reduce the hollow hole on the output optical fiber to be closed, cutting the tapered end of the output optical fiber and performing coupling fusion welding with the input optical fiber; at the coupling fusion joint, the hollow core hole on the end face of the output optical fiber is completely closed, the radius of the end face of the output inner cladding is recorded as r3, r3 is more than or equal to r1, and r1 is the radius of the input fiber core; when the output optical fiber is a hollow optical fiber, the following relation is satisfied:
wherein L is 0 The radial length of the tapered region of the output optical fiber before tapering is defined, the end face radius of the output outer cladding is recorded as R3, R2 is the radius of the output core, T2 is the cross-sectional thickness of the output inner cladding, and R2 is the outer radius of the output outer cladding;
or when the refractive index of the output fiber core is greater than 1, the output fiber core is a solid medium, the output fiber is a solid fiber with a double-layer cladding structure, and the coupling fusion welding step of the input fiber and the output fiber is as follows: performing equal-proportion tapering on one end of the output optical fiber to enable the output fiber core, the output inner cladding and the output outer cladding to be uniformly reduced, cutting the tapered end of the output optical fiber and performing coupling fusion with the input optical fiber; at the coupling fusion joint, the radius of the end face of the output fiber core is recorded as r3', the thickness of the end face of the output inner cladding is recorded as T3, and r3' + T3 is more than or equal to r1 and more than r3 '; at the coupling welding position, the end face radius of the output outer cladding layer is recorded as R3, and R3' is more than or equal to R3 and less than or equal to 400 mu m; when the output optical fiber is a solid optical fiber, the following relation is satisfied:
wherein L is 0 Is the radial length of the tapered region of the output fiber before tapering.
2. A ring laser output device as claimed in claim 1, wherein the numerical aperture of the input core is denoted as NA1 and satisfies 0.03 ≦ NA1 ≦ 1;
the radius of the input fiber core is recorded as r1, and the radius is more than 0 and less than or equal to r1 and less than or equal to 25 mu m;
the radius of the input cladding is recorded as R1, and the R1 is equal to or more than 52.5 and is equal to or less than 200 mu m.
3. A ring laser output device as claimed in claim 2, wherein the numerical aperture formed by the output inner cladding and the output outer cladding is NA2, the numerical aperture formed by the output core and the output inner cladding is NA3, and satisfies NA2 ≤ 1, NA2 ≤ NA 3;
and after tapering, the radial length of the output optical fiber taper area is recorded as L, and L is more than or equal to 5mm and less than or equal to 500 mm.
4. The ring laser output device of claim 3, wherein the radius of the output core is denoted as r2 and satisfies 0< r2 ≦ 100 μm, the radius of the output core matching the central dark spot size of the ring beam generated by the ring laser output device;
the cross-sectional thickness of the output inner cladding is recorded as T2, r1 is not less than T2 is not less than 200 mu m, and the cross-sectional thickness of the output inner cladding is matched with the width of the annular light beam generated by the annular laser output device;
the outer radius of the output outer cladding is recorded as R2, and R2+ T2 is not less than R2 is not less than 500 μm.
5. A ring laser output device as claimed in claim 1, wherein the package is a metal housing having a protective function, and the filler is a polymer for fixing the input and output optical fibers and protecting the surfaces of the input and output optical fibers from the wet gas and the friction of external force.
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