A cascaded cladding mode stripper and a manufacturing method thereof

Abstract

The present invention discloses a cascaded cladding light stripper and a manufacturing method thereof. The cladding light stripper includes a first optical fiber, a second optical fiber, a quartz tube and a metal shell. The cascaded cladding light stripper proposed by the present invention can gradually strip the cladding light layer by layer through cascading multiple cladding light strippers and the segmented etching method, and guide away the cladding light or the heat generated by the cladding light step by step and stage by stage, so as to achieve high-power cladding light stripping, effectively avoid local high temperature, and can be applied to high-power fiber lasers; moreover, the manufacturing difficulty is low.

Description

Technical Field

[0001] The present invention relates to the field of lasers, and particularly to a cascaded cladding light stripper and a manufacturing method thereof. Background Art

[0002] In high-power all-fiber lasers, the cladding structure of double-clad fibers inevitably contains residual pump light, amplified spontaneous emission, and signal light leaked due to factors such as non-ideal splicing and fiber bending. These cladding lights will deteriorate the beam quality of the output laser, and even damage the semiconductor pump source and other fiber devices in the laser system, thus seriously affecting the stability of the laser. Therefore, how to reliably and efficiently strip the cladding light from the cladding waveguide is one of the key issues in the development of high-power all-fiber lasers.

[0003] A cladding light stripper (CLS) is a passive device used to filter out the cladding light in the fiber. Its basic working principle is to destroy the total reflection condition for the transmission of the cladding light, so that the cladding light refracts or scatters out of the inner cladding. When preparing a CLS based on coating a high refractive index glue in the traditional way, the device needs to work stably under high-intensity water-cooled heat sink cooling, and the heat dissipation problem needs to be fully considered during use. In addition, the high refractive index glue itself has poor high-temperature tolerance, which limits the power-carrying capacity of this type of device. In addition, there is also a corrosion-type CLS in the prior art. Under the condition of no active cooling, the corrosion-type CLS directly scatters the cladding light into the air. No medium prone to thermal damage is introduced during the device preparation process, which greatly improves the heat treatment ability of the device. The power carried by the CLS reaches several hundred watts, and it has a high stripping coefficient at a suitable length, showing great advantages in high-power applications. However, the traditional high-power corrosion-type cladding light stripper generally only includes one cladding light stripping region, which bears a large amount of heat, resulting in a relatively fast temperature rise and being prone to burnout, which is not conducive to realizing high-power laser output. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a cascaded cladding light stripper and method.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A cascaded cladding light stripper includes a first optical fiber, a second optical fiber, a quartz tube, and a metal shell;

[0007] The first optical fiber includes a first core, a first cladding covering the first core, and a first polymer coating covering the first cladding; at one end of the first optical fiber, there is also a bare area where the first polymer coating is stripped off to expose the first cladding;

[0008] The second optical fiber includes a second core, a second cladding covering the second core, and a second polymer coating layer covering the second cladding; at one end of the second optical fiber, there is also a bare area where the second polymer coating layer is stripped off to expose the second cladding;

[0009] One end of the first optical fiber exposing the first cladding is correspondingly fusion - welded to one end of the second optical fiber exposing the second cladding;

[0010] The quartz tube is sleeved outside the fusion - welding part of the first optical fiber and the second optical fiber, and one end of the quartz tube is sleeved outside the bare area where the first optical fiber has its first polymer coating layer stripped off and exposes the second cladding, and the other end is sleeved outside the bare area where the second optical fiber has its second polymer coating layer stripped off and exposes the second cladding;

[0011] The metal shell is sleeved outside the quartz tube;

[0012] The bare area of the first optical fiber exposing the first cladding contains several corrosion areas.

[0013] In some embodiments, the bare area of the first optical fiber exposing the first cladding contains a first corrosion area and a second corrosion area, and the corrosion degree of the first corrosion area is higher than that of the second corrosion area.

[0014] In some embodiments, the bare area of the second optical fiber exposing the second cladding contains a third corrosion area and a fourth corrosion area, and the corrosion degree of the third corrosion area is lower than that of the fourth corrosion area.

[0015] In some embodiments, the diameter of the first core is 20μm, and the diameter of the first cladding is 400μm; the diameter of the second core is 10μm, and the diameter of the second cladding is 125μm.

[0016] In some embodiments, the diameter of the first core is 25μm, and the diameter of the first cladding is 400μm; the diameter of the second core is 14μm, and the diameter of the second cladding is 250μm.

[0017] In some embodiments, a rough scattering surface is formed by corrosion on the outer surface of the quartz tube; a heat - conducting material is arranged inside the quartz tube.

[0018] In some embodiments, the heat - conducting material is a ring - shaped sapphire.

[0019] A manufacturing method of the above - mentioned cascaded cladding - mode stripper includes the following steps:

[0020] Step 1: First, take out a first optical fiber and a second optical fiber, then strip off a section of the polymer coating layer of the first optical fiber to expose its first cladding, and strip off a section of the polymer coating layer of the second optical fiber to expose its second cladding;

[0021] Step 2: Corrode the surface of the first cladding exposed by the first optical fiber with two different concentrations of corrosives to obtain a first corrosion zone and a second corrosion zone with two scattering surfaces of different roughnesses;

[0022] Or, use two different concentrations of corrosives to corrode the surface of the first cladding exposed by the first optical fiber and the surface of the second cladding exposed by the second optical fiber respectively. A first corrosion zone and a second corrosion zone with two scattering surfaces of different roughnesses are formed on the surface of the first cladding exposed by the first optical fiber, and a third corrosion zone and a fourth corrosion zone with two scattering surfaces of different roughnesses are formed on the surface of the second cladding exposed by the second optical fiber;

[0023] Step 3: Cut the first optical fiber and the second optical fiber so that the area where the first cladding is exposed on the first optical fiber is located at the end of the cut first optical fiber, and the area where the second cladding is exposed on the second optical fiber is located at the end of the cut second optical fiber;

[0024] Step 4: Fuse the end of the first cladding exposed by the cut first optical fiber with the end of the second cladding exposed by the cut second optical fiber;

[0025] Step 5: Take a quartz tube with a suitable size and corrode a rough scattering surface on the outer surface of the quartz tube with a corrosive;

[0026] Step 6: Sleeve the quartz tube on the fusion joint of the first optical fiber and the second optical fiber, and sleeve one end of the quartz tube on the outside of the first cladding exposed by the first optical fiber and the other end on the outside of the second cladding exposed by the second optical fiber;

[0027] Step 7: Embed heat-conducting materials at both inner ends of the quartz tube for sealing and reinforcement;

[0028] Step 8: Take a metal shell with a suitable size and sleeve it on the outside of the quartz tube.

[0029] A cascaded cladding optical stripper and its manufacturing method proposed by the present invention can strip the cladding light layer by layer, effectively avoid local high temperature, and can be applied to high-power fiber lasers and narrow-linewidth fiber lasers.

[0030] Compared with the prior art, the advantages of the present invention include:

[0031] (1) For traditional cladding optical strippers, the whole cladding light is stripped through high-refractive-index glue. However, due to the poor heat resistance of the glue, it is very difficult for the whole cladding optical stripper to achieve cladding light stripping of hundreds of watts. The cascaded cladding optical stripper proposed by the present invention gradually strips the cladding light layer by layer through a cascaded cladding optical stripper group and a segmented corrosion method, and can achieve high-power cladding light stripping.

[0032] (2) The traditional corrosive high-power cladding light stripper has a too high stripping power for a single cladding light stripper when the cladding light has a high power, bears a large thermal accumulation pressure, and is prone to generating local high-temperature areas, and it is necessary to remove the heat through rapid water cooling; the present invention proposes a cascaded cladding light stripper, by forming multiple corrosion zones, which is equivalent to the cascade of multiple cladding light strippers, and can conduct the cladding light or the heat generated by the cladding light step by step and stage by stage, so as to avoid local high-temperature hot spots, and even in many cases, water cooling is not required.

[0033] (3) For the cladding light stripper applied to the traditional 10 / 125μm optical fiber, due to the small size of the optical fiber, it is easy to break during the manufacturing process if the optical fiber cladding is corroded; the present invention does not corrode the 10 / 125μm size optical fiber, but corrodes the quartz tube, and the quartz tube takes away the heat, reducing the manufacturing difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other objects and advantages of the present invention will be apparent from the following description of the present invention with reference to the accompanying drawings, and can help to have a comprehensive understanding of the present invention.

[0035] Figure 1 It is a schematic diagram of the cascaded cladding light stripper in the first embodiment;

[0036] Figure 2 It is a schematic diagram of the cascaded cladding light stripper in the second embodiment;

[0037] DESCRIPTION OF THE REFERENCE NUMERALS:

[0038] 1. First optical fiber; 2. Second optical fiber; 3. Quartz tube; 4. Heat-conducting material; 5. Metal shell; 1.1. First core; 1.2. First cladding; 1.3. First polymer coating layer; 1.4. First corrosion zone; 1.5 First corrosion zone; 2.1. Second core; 2.2. Second cladding; 2.3. Second polymer coating layer; 2.4. Third corrosion zone; 2.5 Fourth corrosion zone. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0040] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meaning understood by those of ordinary skill in the art to which the present invention belongs.

[0041] Refer toFigure 1 , the present invention provides a cascaded cladding optical stripper, which includes a first optical fiber 1, a second optical fiber 2, a quartz tube 3 and a metal shell 5;

[0042] Wherein, the first optical fiber 1 includes a first core 1.1, a first cladding 1.2 covering the first core 1.1, and a first polymer coating layer 1.3 covering the first cladding 1.2; at one end of the first optical fiber 1, there is also a bare area where the first polymer coating layer 1.3 is stripped off and the first cladding 1.2 is exposed; and the bare area of the first optical fiber 1 where the first cladding 1.2 is exposed contains several corrosion areas;

[0043] The second optical fiber 2 includes a second core 2.1, a second cladding 2.2 covering the second core 2.1, and a second polymer coating layer 2.3 covering the second cladding 2.2; at one end of the second optical fiber 2, there is also a bare area where the second polymer coating layer 2.3 is stripped off and the second cladding 2.2 is exposed;

[0044] One end of the first optical fiber 1 where the first cladding 1.2 is exposed is correspondingly fused with one end of the second optical fiber 2 where the second cladding 2.2 is exposed;

[0045] The quartz tube 3 is sleeved outside the fusion joint of the first optical fiber 1 and the second optical fiber 2, and one end of the quartz tube 3 is sleeved outside the bare area of the first optical fiber 1 where the first polymer coating layer 1.3 is stripped off and the second cladding 2.2 is exposed, and the other end is sleeved outside the bare area of the second optical fiber 2 where the second polymer coating layer 2.3 is stripped off and the second cladding 2.2 is exposed;

[0046] The metal shell 5 is sleeved outside the quartz tube 3.

[0047] Preferably, a rough scattering surface is formed by corrosion on the outer surface of the quartz tube 3.

[0048] In Figure 1 In the first embodiment shown, the bare area of the first optical fiber 1 where the first cladding 1.2 is exposed contains a first corrosion area 1.4 and a second corrosion area 1.5, and the corrosion degree of the first corrosion area 1.4 is higher than that of the second corrosion area 1.5.

[0049] Specifically, the first optical fiber 1 can correspond to a 20 / 400μm passive optical fiber, that is, the diameter of the first core 1.1 is 20μm, and the diameter of the first cladding 1.2 is 400μm; the second optical fiber 2 can correspond to a 10 / 125μm passive optical fiber, that is, the diameter of the second core 2.1 is 10μm, and the diameter of the second cladding 2.2 is 125μm.

[0050] In this embodiment, since the size of the second optical fiber 2 is relatively small, it is easy to break during the manufacturing process if the optical fiber cladding is corroded. Therefore, the 10 / 125μm-sized second optical fiber 2 is not corroded. At this time, the quartz tube 3 can be corroded to form a rough scattering surface on the outer surface of the quartz tube 3, and the heat is taken away through the quartz tube 3, thus reducing the manufacturing difficulty of the device.

[0051] In the second embodiment, as Figure 2 shown, not only does the first optical fiber 1 include a first corrosion zone 1.4 and a second corrosion zone 1.5, but the exposed area where the second optical fiber 2 exposes the second cladding 2.2 includes a third corrosion zone 2.4 and a fourth corrosion zone 2.5, and the corrosion degree of the third corrosion zone 2.4 is lower than that of the fourth corrosion zone 2.5.

[0052] Specifically, the first optical fiber 1 can correspond to a 25 / 400μm passive optical fiber, that is, the diameter of the first core 1.1 is 25μm, and the diameter of the first cladding 1.2 is 400μm; the second optical fiber 2 can correspond to a 14 / 250μm passive optical fiber, that is, the diameter of the second core 2.1 is 14μm, and the diameter of the second cladding 2.2 is 250μm.

[0053] In this embodiment, the sizes of the first optical fiber 1 and the second optical fiber 2 are both large enough, so both of them are corroded to form more corrosion zones, which can layer by layer strip the cladding light and effectively avoid local high temperature, and can be better applied in high-power fiber lasers.

[0054] It can be understood that the above-mentioned first embodiment and the second embodiment are only two exemplary specific embodiments, and the protection scope of the present invention is not limited thereto. The position and number of the corrosion zones can be changed according to actual needs.

[0055] Preferably, a heat-conducting material 4 is further provided inside the quartz tube 9. More preferably, the heat-conducting material 4 is made of annular sapphire, and the annular sapphire can be spliced with the quartz tube 3 through a high-refractive-index glue.

[0056] In addition, the quartz tube 3 can be a capillary quartz tube; the metal shell 5 is preferably made of ferrous metal.

[0057] On the other hand, the present invention provides a manufacturing method of the above-mentioned cascaded cladding light stripper, including the following steps:

[0058] Step 1: First, take out a first optical fiber 1 and a second optical fiber 2, then strip off a section of the polymer coating layer at one end of the first optical fiber 1 to expose its first cladding 1.2, and strip off a section of the polymer coating layer at one end of the second optical fiber 2 to expose its second cladding 2.2;

[0059] Step 2: Corrode the surface of the exposed first cladding 1.2 of the first optical fiber 1 with two different concentrations of corrosives (such as hydrofluoric acid or other fluorides) to obtain a first corrosion zone 1.3 and a second corrosion zone 1.4 with two scattering surfaces of different roughnesses (corresponding to Figure 1 the first embodiment shown);

[0060] Alternatively, use two different concentrations of corrosives to corrode the surface of the exposed first cladding 1.2 of the first optical fiber 1 and the surface of the exposed second cladding 2.2 of the second optical fiber 2 respectively, form a first corrosion zone 1.3 and a second corrosion zone 1.4 with two scattering surfaces of different roughnesses on the surface of the exposed first cladding 1.2 of the first optical fiber 1, and form a third corrosion zone 2.3 and a fourth corrosion zone 2.4 with two scattering surfaces of different roughnesses on the surface of the exposed second cladding 2.2 of the second optical fiber 2 (corresponding to Figure 2 the second embodiment shown);

[0061] Step 3: Cut the first optical fiber 1 and the second optical fiber 2 so that the area of the first optical fiber 1 where the first cladding 1.2 is exposed is located at the end of the cut first optical fiber 1, and the area of the second optical fiber 2 where the second cladding 2.2 is exposed is located at the end of the cut second optical fiber 2;

[0062] Step 4: Fuse the end of the exposed first cladding 1.2 of the cut first optical fiber 1 with the end of the exposed second cladding 2.2 of the cut second optical fiber 2;

[0063] Step 5: Take a quartz tube 3 with a suitable size, and use a corrosive to corrode a rough scattering surface on the outer surface of the quartz tube 3; on the surface of the quartz tube 3, perform mild corrosion (mild relative to the corrosion degree of the corrosion zone), and a slightly rough scattering surface can be obtained;

[0064] Step 6: Sleeve the quartz tube 3 on the fusion joint of the first optical fiber 1 and the second optical fiber 2, and sleeve one end of the quartz tube 3 on the outside of the exposed first cladding 1.2 of the first optical fiber 1, and the other end on the outside of the exposed second cladding 2.2 of the second optical fiber 2;

[0065] Step 7: Embed a heat-conducting material 4 at both inner ends of the quartz tube 3 for sealing and reinforcement; the heat-conducting material 4 is preferably an annular sapphire, and the annular sapphire can be spliced and fixed with the quartz tube 3 through a high-refractive-index glue;

[0066] Step 8: Take a metal shell 5 with a suitable size and sleeve it on the outside of the quartz tube 3, and the manufacturing of the cascaded cladding optical stripper is completed.

[0067] When the cascaded cladding optical stripper provided by the present invention is in use, optical stripping is performed through the etching area and the scattering surface on the quartz tube 3. The scattered light is guided to the metal shell 5 through the quartz tube 3. Then, if necessary, for example, when the laser power is particularly high, a water channel can be dug outside the metal shell 5, and heat can be further removed through the traditional water cooling method.

[0068] In summary, a cascaded cladding optical stripper and its manufacturing method proposed by the present invention can strip the cladding light layer by layer, effectively avoid local high temperature, and can be applied to high-power fiber lasers.

[0069] Compared with the prior art, for the traditional cladding optical stripper, the whole cladding light is stripped through high-refractive-index glue. However, due to the poor heat resistance of the glue, it is very difficult for the whole cladding optical stripper to achieve cladding light stripping at the hundred-watt level. The cladding optical stripper proposed by the present invention can gradually strip the cladding light layer by layer through the segmented etching method, and can achieve high-power cladding light stripping.

[0070] For the traditional corrosion-type high-power cladding optical stripper, when the cladding light has a relatively high power, the stripping power of a single cladding optical stripper is too high, and it bears a large thermal accumulation pressure, and it is easy to generate local high-temperature areas, and heat needs to be removed through rapid water cooling. The cascaded cladding optical stripper proposed by the present invention can guide the cladding light or the heat generated by the cladding light step by step and stage by stage by forming multiple etching areas, which is equivalent to the cascading of multiple cladding optical strippers, so as to avoid local hot spots, and even water cooling is not required in many cases.

[0071] For the cladding optical stripper applied to the traditional 10 / 125μm optical fiber, due to the small size of the optical fiber, it is easy to break if the cladding of the optical fiber is etched during the manufacturing process. The present invention does not etch the 10 / 125μm-sized optical fiber, but etches the quartz tube, and the heat is taken away through the quartz tube, reducing the manufacturing difficulty.

[0072] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A cascaded cladding optical stripper, characterized in that, It includes a first optical fiber (1), a second optical fiber (2), a quartz tube (3) and a metal shell (5); The first optical fiber (1) includes a first core (1.1), a first cladding (1.2) covering the first core (1.1), and a first polymer coating layer (1.3) covering the first cladding (1.2); at one end of the first optical fiber (1), there is also a bare area where the first polymer coating layer (1.3) is stripped off and the first cladding (1.2) is exposed; The second optical fiber (2) includes a second core (2.1), a second cladding (2.2) covering the second core (2.1), and a second polymer coating layer (2.3) covering the second cladding (2.2); at one end of the second optical fiber (2), there is also a bare area where the second polymer coating layer (2.3) is stripped off and the second cladding (2.2) is exposed; The end of the first optical fiber (1) where the first cladding (1.2) is exposed is correspondingly fused with the end of the second optical fiber (2) where the second cladding (2.2) is exposed; The quartz tube (3) is sleeved outside the fusion joint of the first optical fiber (1) and the second optical fiber (2), and one end of the quartz tube (3) is sleeved outside the bare area where the first polymer coating layer (1.3) of the first optical fiber (1) is stripped off and the second cladding (2.2) is exposed, and the other end is sleeved outside the bare area where the second polymer coating layer (2.3) of the second optical fiber (2) is stripped off and the second cladding (2.2) is exposed; The metal shell (5) is sleeved outside the quartz tube (3); The bare area of the first optical fiber (1) where the first cladding (1.2) is exposed contains several corrosion areas; The bare area of the first optical fiber (1) where the first cladding (1.2) is exposed contains a first corrosion area (1.4) and a second corrosion area (1.5), and the corrosion degree of the first corrosion area (1.4) is higher than that of the second corrosion area (1.5); The bare area of the second optical fiber (2) where the second cladding (2.2) is exposed contains a third corrosion area (2.4) and a fourth corrosion area (2.5), and the corrosion degree of the third corrosion area (2.4) is lower than that of the fourth corrosion area (2.5); The quartz tube (3) is a capillary quartz tube.

2. The cascaded cladding optical stripper according to claim 1, characterized in that, The diameter of the first core (1.1) is 25μm, and the diameter of the first cladding (1.2) is 400μm; the diameter of the second core (2.1) is 14μm, and the diameter of the second cladding (2.2) is 250μm.

3. The cascaded cladding optical stripper according to any one of claims 1 to 2, characterized in that, A rough scattering surface is corroded and formed on the outer surface of the quartz tube (3); a heat-conducting material (4) is arranged inside the quartz tube (3).

4. The cascaded cladding optical stripper according to claim 3, characterized in that, The heat-conducting material (4) is a ring-shaped sapphire.

5. A manufacturing method of the cascaded cladding optical stripper according to claim 3, characterized in that, It includes the following steps: Step 1: First, take out a first optical fiber (1) and a second optical fiber (2), then strip off a section of the polymer coating layer of the first optical fiber (1) to expose its first cladding (1.2), and strip off a section of the polymer coating layer of the second optical fiber (2) to expose its second cladding (2.2); Step 2: Corrode the surface of the exposed first cladding (1.2) of the first optical fiber (1) with two different concentrations of corrosive substances to obtain a first corrosion zone (1.3) and a second corrosion zone (1.4) with different roughness scattering surfaces; Alternatively, corrode the surface of the exposed first cladding (1.2) of the first optical fiber (1) and the surface of the exposed second cladding (2.2) of the second optical fiber (2) with two different concentrations of corrosive substances respectively. A first corrosion zone (1.3) and a second corrosion zone (1.4) with different roughness scattering surfaces are formed on the surface of the exposed first cladding (1.1) of the first optical fiber (1), and a third corrosion zone (2.3) and a fourth corrosion zone (2.4) with different roughness scattering surfaces are formed on the surface of the exposed second cladding (2.2) of the second optical fiber (2); Step 3: Cut the first optical fiber (1) and the second optical fiber (2) so that the region of the first optical fiber (1) where the first cladding (1.2) is exposed is located at the end of the cut first optical fiber (1), and the region of the second optical fiber (2) where the second cladding (2.2) is exposed is located at the end of the cut second optical fiber (2); Step 4: Fusion splice the end of the exposed first cladding (1.2) of the cut first optical fiber (1) with the end of the exposed second cladding (2.2) of the cut second optical fiber (2); Step 5: Take a quartz tube (3) and corrode a rough scattering surface on the outer surface of the quartz tube (3) with a corrosive substance; Step 6: Sleeve the quartz tube (3) on the fusion splicing part of the first optical fiber (1) and the second optical fiber (2), and sleeve one end of the quartz tube (3) outside the exposed first cladding (1.2) of the first optical fiber (1) and the other end outside the exposed second cladding (2.2) of the second optical fiber (2); Step 7: Embed heat-conducting materials (4) at both inner ends of the quartz tube (3) for sealing and reinforcement; Step 8: Take a metal shell (5) and sleeve it on the outside of the quartz tube (3).

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