A pump recycling device and a preparation method thereof

Abstract

The present invention provides a pump recovery device and a preparation method thereof. The pump recovery device is obtained by preparing a fiber taper part through fusing and tapering a plurality of pump arms located in a second sub-part, an input signal optical fiber in the second sub-part, and the second sub-part. More pump arms enable the remaining pump light to enter the output signal optical fiber from more directions and positions, so that the gain optical fiber can absorb it again, thereby improving the overall pump efficiency and effectively utilizing the remaining pump light. At the same time, the fiber taper part is fused with the output signal optical fiber, making the structure of the pump recovery device more compact, reducing the number of connection components and interfaces between optical fibers, and further realizing low-loss transmission of optical signals.

Description

Technical Field

[0001] The present invention relates to the technical field of optical devices, and in particular, to a pump recovery device and a preparation method thereof. Background Art

[0002] High-power narrow-linewidth fiber lasers have wide application values in fields such as gravitational wave detection, coherent communication, lidar, nonlinear frequency conversion, laser weapons, coherent beam combining, and spectral beam combining. In order to suppress nonlinear effects such as stimulated Brillouin scattering and stimulated Raman scattering in narrow-linewidth fiber lasers, the length of the gain fiber of the laser is usually shortened to increase the laser output power. In this case, it is inevitable to increase the content of the remaining pump light in the laser, resulting in a decrease in the laser conversion efficiency of the system; at the same time, the excess pump light will also increase the thermal load of the system, posing a potential safety hazard to the laser system.

[0003] In the existing solutions for reducing the remaining pump light in narrow-linewidth fiber lasers, there are mainly two methods. The first method is to design a gain fiber with high absorption under the same fiber length to increase the total pump absorption, improve the pump light conversion rate, and reduce the content of the remaining pump light; the second method is to recycle and reuse the pump light by connecting the pump arms of the combiner in the laser system structure. The first method requires the design of the ion doping concentration of the gain fiber, and the scheme is complex. While increasing the absorption coefficient, new variables may also be introduced, such as mode instability effects, to reduce the output power of the system; the second method requires the connection of the pump arms of the combiner, introducing new melting points. The fusion will cause a certain loss of laser efficiency, and at the same time, the treatment of the melting points will also increase the system complexity.

[0004] Therefore, there is an urgent need for a pump recovery device and a preparation method thereof to solve the above technical problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a pump recovery device and a preparation method thereof, which are used to improve the technical problem that the existing lasers are difficult to recover the remaining pump light.

[0006] To solve the above technical problems, the present invention provides a pump recovery device, which includes an input signal fiber, multiple pump fibers, a fiber fixator, a quartz tube, and an output signal fiber. The pump arms of the multiple pump fibers and the input signal fiber all axially penetrate through the fiber fixator completely and are fixed in the quartz tube. The quartz tube includes a first sub-part and a second sub-part connected axially. The first sub-part is arranged close to the fiber fixator, and the second sub-part is arranged close to the output signal fiber;

[0007] Among them, multiple pump arms located in the second sub - part, the input signal optical fiber in the second sub - part, and the second sub - part form an optical fiber taper part through the fused biconical taper process; one end of the optical fiber taper part far from the optical fiber fixture is fused with the output signal optical fiber.

[0008] Preferably, the optical fiber fixture is any one of a honeycomb fixture and a porous fixture; the optical fiber fixture includes a first opening and a second opening. The first opening is located at the central position of the optical fiber fixture, and multiple second openings are arranged around the first opening, and the central axes of the multiple second openings are parallel to each other.

[0009] Preferably, the input signal optical fiber axially penetrates through the first opening completely, and the pump arm axially penetrates through the second opening completely.

[0010] Among them, the two pump arms of the same pump optical fiber are symmetrical about the input signal optical fiber.

[0011] Preferably, the sum of the cladding diameters of the two pump arms and the cladding diameter of the input signal optical fiber is less than the inner diameter of the quartz tube; the input signal optical fiber located in the quartz tube has a clearance fit with its adjacent multiple pump arms, and the multiple pump arms have a clearance fit with the inner wall of the quartz tube.

[0012] Preferably, both the input signal optical fiber and the output signal optical fiber are double - clad passive optical fibers or double - clad polarization - maintaining passive optical fibers, and the working bands of the input signal optical fiber and the output signal optical fiber both include any one of the 1.0 µm band, 1.5 µm band, and 2.0 µm band.

[0013] Correspondingly, the present invention also provides a preparation method of a pump recovery device as described in any one of the above, and the method includes the following steps:

[0014] S10, axially penetrate the pump arms of multiple pump optical fibers and the input signal optical fiber completely through the optical fiber fixture and fix them in the quartz tube.

[0015] S20, perform a fused biconical taper treatment on the pump arms inserted into the quartz tube, the part of the input signal optical fiber inserted into the quartz tube, and part of the quartz tube to obtain an optical fiber taper part.

[0016] S30, cut part of the optical fiber taper part, and make the end of the optical fiber taper part far from the optical fiber fixture axially opposite to the output signal optical fiber and fuse it with the output signal optical fiber.

[0017] Preferably, in step S10, before inserting the pump arm and the input signal optical fiber into the quartz tube, it further includes: respectively removing the coating layers of the pump arm and the input signal optical fiber.

[0018] Preferably, after removing the coating layer of the pump arm and before inserting the pump arm into the quartz tube, it further includes: performing a biconical taper treatment on the pump arm to reduce the cladding diameter of the pump arm.

[0019] Preferably, before removing the coating layer of the input signal optical fiber and inserting the input signal optical fiber into the quartz tube, the method further includes: performing a cladding etching process on the input signal optical fiber, and the cladding etching method is hydrofluoric acid treatment.

[0020] Preferably, in step S30: the cutting angle of the optical fiber taper is within 1.5°.

[0021] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention provides a pump recovery device and a preparation method thereof. The above pump recovery device is prepared by using a plurality of pump arms located in the second sub-part, the input signal optical fiber in the second sub-part, and the second sub-part through a fused biconical taper process to obtain an optical fiber taper. More pump arms enable the remaining pump light in the laser system to enter the output signal optical fiber from more directions and positions, thereby improving the overall pump efficiency and effectively utilizing the remaining pump light. At the same time, the optical fiber taper is fused with the output signal optical fiber, making the structure of the pump recovery device more compact, reducing the number of connection components and interfaces between optical fibers, and further realizing low-loss transmission of optical signals. Description of the Drawings

[0022] Figure 1 is a schematic radial structure diagram of the pump recovery device provided by an embodiment of the present invention;

[0023] Figure 2 is a schematic three-dimensional structure diagram of the optical fiber fixer in the pump recovery device provided by an embodiment of the present invention;

[0024] Figure 3 is a flow chart of the preparation method of the pump recovery device provided by an embodiment of the present invention;

[0025] Figure 4 is a schematic radial diagram before the tapering step in the preparation method of the pump recovery device provided by an embodiment of the present invention;

[0026] Figure 5 is an axial cross-sectional schematic diagram of the tapering step in the preparation method of the pump recovery device provided by an embodiment of the present invention;

[0027] Figure 6 is a schematic radial diagram of the welding step in the preparation method of the pump recovery device provided by an embodiment of the present invention;

[0028] In the drawings: 100 - pump recovery device; 10 - pump optical fiber; 11 - pump arm; 20 - input signal optical fiber; 30 - optical fiber fixer; 31 - first opening; 32 - second opening; 40 - quartz tube; 41 - optical fiber taper; 50 - output signal optical fiber. Detailed Embodiments

[0029] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] The object of the present invention is to provide a pump recovery device for the defects of the prior art, which can improve the pump recovery rate by increasing the number of pump fibers. The present invention utilizes the two arms of the pump fiber to recover the remaining pump light, which can reduce operations such as optimizing the length or doping concentration of the gain fiber or processing optical devices in the fiber laser system; increasing the number of pump fibers can improve the pump recovery rate.

[0031] The technical solutions of the present invention will now be described in conjunction with specific embodiments.

[0032] Please refer to Figure 1 , Figure 1 , which is a schematic radial structure diagram of the pump recovery device 100 provided by the embodiment of the present invention; specifically, the above-mentioned pump recovery device 100 includes an input signal fiber 20, multiple pump fibers 10, a fiber fixator 30, a quartz tube 40, and an output signal fiber 50. The pump arms 11 of the multiple pump fibers 10 and the input signal fiber 20 both axially penetrate through the fiber fixator 30 completely and are fixed in the quartz tube 40.

[0033] Among them, the quartz tube 40 includes a first sub-part and a second sub-part connected axially. The first sub-part is arranged close to the fiber fixator 30, and the second sub-part is arranged close to the output signal fiber 50.

[0034] Among them, multiple pump arms 11 located in the second sub-part, the input signal fiber 20 in the second sub-part, and the second sub-part form a fiber taper part 41 through the fused biconical taper process; one end of the fiber taper part 41 away from the fiber fixator is fused to the output signal fiber 50.

[0035] In the embodiment of the present invention, the input signal fiber 20 is used to externally connect a seed light source, and then transmit it in the internal structure of the pump recovery device 100, and then cooperate with other components to realize functions such as relevant processing and transmission of optical signals.

[0036] In the embodiment of the present invention, multiple pump fibers 10 are used to introduce the remaining pump light in the laser system into the pump recovery device 100, and provide energy support for the gain fiber again, such as participating in relevant processes such as optical amplification, and helping to improve the relevant performance of optical signals.

[0037] Figure 2It is a schematic diagram of the three-dimensional structure of the optical fiber holder 30 in the pump recoverer 100 provided in an embodiment of the present invention; wherein, the optical fiber holder 30 includes a first opening 31 and a second opening 32, the first opening 31 is located at the center of the optical fiber holder 30, and a plurality of second openings 32 are arranged around the first opening 31, and the central axis of the plurality of second openings 32 and the first opening 31 are parallel to each other.

[0038] Specifically, the optical fiber holder 30 is any one of a honeycomb clamp and a porous clamp; wherein the optical fiber holder 30 plays a role in fixing and limiting the input signal optical fiber 20 and the pump optical fiber 10, ensuring that they are in accurate positions before subsequent operations such as being loaded into the quartz tube 40, ensuring the regularity of the entire structure and the rationality of the relative position relationship between the optical fibers, which is very important for the effective coupling of light.

[0039] Specifically, the input signal fiber 20 completely penetrates the first opening 31 along the axial direction, and the pump arm 11 completely penetrates the second opening 32 along the axial direction; the two pump arms 11 of the same pump fiber 10 are symmetrical with the input signal fiber 20 as the axis.

[0040] Furthermore, the input signal optical fiber 20 completely passes through the first opening 31 of the optical fiber holder 30 along the axial direction. Such a design can accurately determine the position of the input signal optical fiber 20 in the entire pump recycler 100 structure, thereby preventing the input signal optical fiber 20 from being offset or shaken during subsequent assembly and use. Because the first opening 31 is located at the center of the optical fiber holder 30, the input signal optical fiber 20 is located at the core of the entire optical fiber layout.

[0041] Furthermore, the pump arm 11 completely penetrates the corresponding second opening 32 along the axial direction, and a plurality of second openings 32 are arranged around the first opening 31, so that the pump arm 11 of the pump fiber 10 is spatially arranged in an orderly manner around the input signal fiber 20. This orderly layout is very critical for the pump light to enter the system and interact with the signal light. It is conducive to achieving efficient coupling of the pump light to the input signal fiber 20. When the pump light is transmitted from the pump arm 11, since each pump arm 11 has a clear and reasonable positional relationship, the pump light can be relatively uniformly and accurately converged to the input signal fiber 20 located in the center, reducing the problems of pump light dispersion and low coupling efficiency that may be caused by disordered arrangement. For example, if the pump arm 11 is placed randomly, the propagation direction of the pump light will be chaotic, and it is difficult to ensure that enough pump light can effectively enter the input signal fiber 20 to provide energy for the signal light or participate in related optical processes. The orderly layout formed by penetrating the second opening 32 can solve this problem well.

[0042] Furthermore, the two pump arms 11 of the same pump fiber 10 are designed to be symmetrical with the input signal fiber 20 as the axis. From the perspective of light field distribution, the pump light can form a relatively uniform light field around the input signal fiber 20. If the two pump arms 11 are asymmetrical, the intensity of the pump light on one side may be much higher than that on the other side, resulting in a significant imbalance in the light field around the input signal fiber 20, which is not conducive to the processing of optical signals and the stability of the entire system. At the same time, this symmetrical setting also plays a balancing role. When the pump light provides energy to the gain medium to amplify the signal light, the uniform light field distribution can ensure that the gain medium at each position can absorb the pump light energy more evenly, avoiding the situation of local excess or insufficient energy.

[0043] In the embodiment of the present invention, the quartz tube 40 includes a first sub-section and a second sub-section connected along the axial direction, the first sub-section is arranged close to the optical fiber holder 30, and the second sub-section is arranged close to the output signal optical fiber 50;

[0044] In the embodiment of the present invention, the quartz tube 40 provides physical support and protection for the internal optical fibers (including the input signal optical fiber 20, the pump optical fiber 10, etc.) on the one hand, and is also involved in the preparation process of the optical fiber taper 41 on the other hand. Its structural characteristics affect the formation of the optical fiber taper 41 and the subsequent transmission of light therein.

[0045] Specifically, a through hole is provided in the quartz tube 40 along the axial direction, the pump arms 11 at both ends of the pump optical fiber 10 are located on the inner periphery of the quartz tube 40, and the input signal optical fiber 20 is located at the center of the quartz tube 40; wherein, a through hole is provided in the quartz tube 40 along the axial direction, and the existence of this through hole provides space and positioning guidance for the placement of the optical fiber. It enables the optical fiber to pass through the quartz tube 40 in an orderly manner along the axial direction, ensuring that each optical fiber is in a relatively fixed and accurate position in the quartz tube 40, which is crucial for the subsequent stable operation of the entire pump recycler 100 and the effective transmission of light therein.

[0046] Furthermore, the pump arm 11 of the pump fiber 10 is arranged on the inner circumference of the quartz tube 40, surrounding the input signal fiber 20 located at the center, so that the pump light can converge towards the input signal fiber 20 from multiple directions. Such a layout is beneficial in the first aspect to improve the coupling efficiency of the pump light to the input signal fiber 20, allowing more pump light to effectively enter the input signal fiber 20 and providing sufficient energy support for subsequent optical signal processing (such as optical amplification, etc.); in the second aspect, the annular distribution of the pump arm 11 around the input signal fiber 20 helps to create a relatively uniform optical field environment around the input signal fiber 20; in the third aspect, this fixed positional relationship enables the fibers to form an orderly and compact layout within the quartz tube 40. When subjected to a certain degree of vibration, due to the clear layout of each fiber and the limiting effect of the quartz tube 40, it can still maintain a normal optical transmission state, ensuring that the pump recovery device 100 continuously and stably performs its functions of recovering pump light and processing optical signals.

[0047] Specifically, the sum of the cladding diameters of the two pump arms 11 and the cladding diameter of the input signal fiber 20 is less than the inner diameter of the quartz tube 40; this size design provides the necessary space margin for the placement of the input signal fiber 20 and the pump fiber 10 within the quartz tube 40. It ensures that the input signal fiber 20 and the pump fiber 10 can be smoothly inserted into the quartz tube 40, avoiding difficulties in installing the input signal fiber 20 and the pump fiber 10 due to overly narrow space, and even possible squeezing, damage, etc. to the input signal fiber 20 and the pump fiber 10, thereby affecting the performance of the input signal fiber 20 and the pump fiber 10 and subsequent optical transmission.

[0048] Specifically, the input signal fiber 20 located within the quartz tube 40 has a clearance fit with the adjacent multiple pump arms 11. This fit means that there is a certain small gap between them, rather than being in close contact. From an optical perspective, the existence of the gap is beneficial to reducing the optical interference that may occur due to direct contact between the fibers.

[0049] Specifically, the multiple pump arms 11 and the inner wall of the quartz tube 40 also have a clearance fit. On the one hand, this facilitates the installation and positioning of the pump arms 11 inside the quartz tube 40, enabling the pump arms 11 to more easily penetrate the quartz tube 40 axially and be in a proper position, avoiding damage to the pump arms 11 that may be caused by interference fit (i.e., the outer diameter of the pump arms 11 is almost equal to or slightly larger than the inner diameter of the quartz tube 40, and forced extrusion is required during installation), and ensuring the integrity of the structure of the pump arms 11 and the normal function of transmitting pump light without being affected. On the other hand, the existence of the clearance also reserves space for the possible thermal expansion and contraction of the quartz tube 40 and the pump arms 11. At different working environmental temperatures, the materials of the quartz tube 40 and the pump arms 11 have different coefficients of thermal expansion. Without this clearance, they may squeeze each other when the temperature changes, damaging the fiber structure or changing the original positional relationship of the fibers, affecting the normal transmission of light and the stability of the system, while the clearance fit can effectively avoid the occurrence of such problems.

[0050] In the embodiments of the present invention, the input signal optical fiber 20 and the output signal optical fiber 50 are both double-clad passive optical fibers or double-clad polarization-maintaining passive optical fibers, and the working bands of the input signal optical fiber 20 and the output signal optical fiber 50 both include any one of the 1.0 µm band, the 1.5 µm band, and the 2.0 µm band. Among them, for the pump recovery device 100, the applicability of its input signal optical fiber 20 and output signal optical fiber 50 in such multiple bands greatly enhances the compatibility between the entire device and different light sources, different optical devices, and different application systems.

[0051] Please refer to Figure 3 , the present invention also provides a preparation method for the pump recovery device 100 as described in any one of the above, and the method includes the following steps:

[0052] S10, completely penetrate the pump arms 11 of multiple pump optical fibers 10 and the input signal optical fiber 20 axially through the optical fiber fixture 30 and fix them in the quartz tube 40.

[0053] Specifically, step S10 further includes:

[0054] Please refer to Figure 1 , Figure 2 and Figure 4 , remove the coating layers from the pump arms 11 at both ends of N pump optical fibers 10 (N ≥ 1) and insert them into the optical fiber fixture 30, remove the coating layer from the input signal optical fiber 20 and insert it into the center of the optical fiber fixture 30, and insert the pump arms 11 at both ends of the pump optical fiber 10 and the input signal optical fiber 20 into the quartz tube 40 for fixation.

[0055] In one embodiment, three pump fibers 10 are selected. A part of the coating layer at each end of the pump fibers 10, the pump arms 11 at both ends of the pump fibers 10, and the respective ends of the input signal fiber 20 are removed. Before the pump arms 11 at both ends of the pump fibers 10 and the input signal fiber 20 are inserted into the quartz tube 40 for fixation, the pump arms 11 at both ends of the pump fibers 10 are tapered to reduce the cladding diameter, and the input signal fiber 20 is subjected to cladding etching. The etching method includes but is not limited to hydrofluoric acid treatment.

[0056] Specifically, by removing the coating layer of the pump arm 11, the pump light can be transmitted more smoothly from the pump arm 11 to the relevant area, and it also enables the input signal fiber 20 to interact with other fibers more effectively in terms of optical signals, reducing problems such as signal attenuation and low coupling efficiency caused by the presence of the coating layer.

[0057] Specifically, the tapering process changes the structure of the pump arm 11, reducing its cladding diameter. On the one hand, this can adjust the optical field distribution of the pump light in the pump arm 11, making the light converge more concentratedly near the core, increasing the energy density of the pump light, and helping the subsequent pump light to be coupled into the input signal fiber 20 more efficiently or to transfer energy to other areas that require the action of the pump light. On the other hand, the pump arm 11 with a reduced cladding diameter can better match the structure and optical field characteristics of other fibers during subsequent operations such as fused tapering with other fibers, further optimizing the transmission and coupling effects of light in the entire system, and enhancing the optical correlation and collaborative working ability between the fibers.

[0058] Specifically, the input signal fiber 20 is subjected to cladding etching, and the etching method includes but is not limited to hydrofluoric acid treatment. Hydrofluoric acid can chemically react with the fiber cladding material (usually silica, etc.) to selectively remove a part of the cladding substance, thereby realizing the adjustment of the cladding thickness or structure. During the fused tapering process, for the input signal fiber 20 after cladding etching, the influence on its core during tapering is reduced, which can effectively weaken the change of the signal fiber core during tapering, thereby reducing the signal insertion loss and reducing mode distortion, ensuring that the signal light is transmitted in the fiber in a more stable and efficient manner and better realizing optical coupling and other interactions with other fibers.

[0059] S20. The pump arm 11 inserted into the quartz tube 40, a part of the input signal fiber 20 inserted into the quartz tube 40, and a part of the quartz tube 40 are subjected to fused tapering to obtain a fiber taper portion 41.

[0060] Specifically, the step S20 further includes:

[0061] Please refer to Figure 1 、 Figure 2 、 Figure 4 and Figure 5, fusion tapering treatment is performed on the pump arms 11, input signal optical fiber 20, and quartz tube 40 at both ends of the fixed pump optical fiber 10 above to form a fiber taper portion 41. The methods for fusion tapering of optical fiber bundles include, but are not limited to, oxyhydrogen flame tapering, graphite tapering, laser tapering, and electrode tapering.

[0062] Specifically, the fusion tapering treatment is to change the structure of the optical fiber to optimize the transmission and coupling of light in the optical fiber. By heating to soften the optical fiber and then stretching to form the fiber taper portion 41, this process can adjust the diameter, refractive index distribution, and optical field mode of the optical fiber. For example, in the pump recovery device 100, the tapered optical fiber can better couple the pump light and the signal light, improving the optical transmission efficiency. At the same time, performing tapering on the pump arms 11, input signal optical fiber 20, and quartz tube 40 at both ends of the pump optical fiber 10 together can cause their structures to change synchronously, thereby forming an integral environment conducive to light interaction in the fiber taper portion 41. The quartz tube 40 can play a role in stabilizing the optical fiber structure during the tapering process, and the change in its own shape also helps to optimize the optical field distribution.

[0063] S30, cut a part of the fiber taper portion 41, and axially align the end of the fiber taper portion 41 away from the optical fiber holder 30 with the output signal optical fiber 50 and fuse it with the output signal optical fiber 50.

[0064] Specifically, the step S30 further includes:

[0065] Please refer to Figure 6 , Figure 6 is a radial schematic diagram of the fusion step in the preparation method of the pump recovery device 100 provided by the embodiment of the present invention. The above steps include: First, cut a part of the fiber taper portion 41 along the radial direction so that the cutting angle of the fiber taper portion 41 is within 1.5°; Second, select an output signal optical fiber 50, the core size of the output signal optical fiber 50 matches the core size of the input signal optical fiber 20, and the cladding size of the output signal optical fiber 50 matches the size of the tapered quartz tube 40; Third, remove the coating layer at the end of the output signal optical fiber 50 and cut it so that the cutting angle is within 1.5°; Finally, axially align the end of the fiber taper portion 41 away from the optical fiber holder 30 with the output signal optical fiber 50 and fuse it with the output signal optical fiber 50.

[0066] Specifically, a cutting angle within 1.5° helps to maintain the optical field matching between the fiber taper portion 41 and the output signal optical fiber 50. If the cutting angle is inappropriate, it will cause a sudden change in the optical field mode, increasing the possibility of optical transmission loss and mode distortion. For example, during the fusion process, an overly large cutting angle may lead to low optical coupling efficiency at the fusion joint, affecting the performance of the entire pump recovery device 100.

[0067] The pump recovery device 100 and its preparation method provided by the embodiments of the present invention can improve the reuse rate of pump light by increasing the number of pump optical fibers 10, achieving the effect of pump recovery. At the same time, since the input signal optical fiber 20 undergoes cladding corrosion before fusion tapering, the change of the signal optical fiber core during the tapering process is weakened, reducing the signal insertion loss and mode distortion.

[0068] Specifically, when the number of pump optical fibers 10 is increased, it means that there are more channels to introduce pump light into the optical system to which the pump recovery device 100 is applied. For example, when there is only one pump optical fiber 10 originally, the pump light power that can be input per unit time is limited, and the absorption of pump light by the gain medium and the like in the system often cannot reach complete absorption, and there will always be some pump light remaining without being fully utilized. As the number of pump optical fibers 10 increases, the total input power of pump light increases accordingly. Even if the absorption efficiency remains at a certain level, the total amount of remaining pump light that is not absorbed will also increase. The design purpose of the pump recovery device 100 is to collect this remaining pump light and reuse it. Therefore, more remaining pump light provides more "raw materials" for recycling and reuse, thereby improving the reuse rate of pump light and better achieving the effect of pump recovery.

[0069] Furthermore, a higher reuse rate of pump light has a positive impact on the entire optical system. It can, to a certain extent, make up for the problem of insufficient utilization of pump light caused by factors such as shortening the length of the gain optical fiber, enabling the system to obtain more available pump light energy without adding too many complex designs (such as changing the doping concentration of the gain optical fiber, etc.), contributing to improving the laser output power and the overall optical conversion efficiency of the system, and reducing negative effects such as an increase in the system's thermal load caused by excessive remaining pump light, ensuring the system operates more stably and efficiently.

[0070] The present invention provides a pump recovery device 100 and its preparation method to reuse the remaining pump light in the laser system. By increasing the number of pump optical fibers 10, the reuse rate of pump light can be improved. At the same time, since the input signal optical fiber 20 undergoes cladding corrosion before fusion tapering, the change of the signal optical fiber core during the tapering process is weakened, reducing the signal insertion loss and mode distortion. It has the advantages of simple structure and reliable performance.

[0071] Of course, the above is only the preferred embodiment of this case, and there can be more variations in specific applications. For example, the number of pump optical fibers 10 of the pump recovery device 100 above is 3. In theory, the number of pump optical fibers 10 only needs to be greater than or equal to 1. As the number of pump optical fibers 10 increases, the pump recovery rate will increase.

[0072] In summary, by providing a pump recovery device 100 and a preparation method thereof, the pump recovery device 100 is connected to a narrow linewidth fiber laser system, and the remaining pump light in the laser can be effectively reused. By increasing the number of pump arms 11, the pump recovery rate can be effectively improved. There is no need to increase the length of the gain fiber or design a complex gain ion distribution to improve the absorption rate of the pump light, nor is it necessary to increase the pump light absorption rate by means of complex operations or devices such as adding a beam combiner and fusing the pump arms or a side pump beam combiner. This solution can simply and efficiently reuse the remaining pump light in the laser.

[0073] It should be noted that the above embodiments all belong to the same inventive concept. The descriptions of the embodiments have their own emphases. For the parts not elaborated in individual embodiments, reference can be made to the descriptions in other embodiments.

[0074] The above embodiments only represent the implementation manners of the present invention. The descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A pump recovery device, characterized in that, It includes an input signal optical fiber, multiple pump optical fibers, an optical fiber fixture, a quartz tube, and an output signal optical fiber. The pump arms of the multiple pump optical fibers and the input signal optical fiber all axially penetrate through the optical fiber fixture and are fixed in the quartz tube. The two pump arms of the same pump optical fiber are symmetrical about the input signal optical fiber. The quartz tube includes a first sub - part and a second sub - part connected axially. The first sub - part is arranged close to the optical fiber fixture, and the second sub - part is arranged close to the output signal optical fiber. Among them, the optical fiber fixture is any one of a honeycomb fixture and a porous fixture. The optical fiber fixture includes a first opening and a second opening. The first opening is located at the central position of the optical fiber fixture. A plurality of the second openings are arranged around the first opening, and the central axes of the plurality of second openings are parallel to each other. Among them, multiple pump arms located in the second sub - part, the input signal optical fiber in the second sub - part, and the second sub - part form an optical fiber taper part through a fused biconical taper process. One end of the optical fiber taper part away from the optical fiber fixture is fusion - spliced with the output signal optical fiber.

2. The pump recovery device according to claim 1, characterized in that, The input signal optical fiber axially penetrates through the first opening completely, and the pump arm axially penetrates through the second opening completely.

3. The pump recovery device according to claim 1, wherein The sum of the cladding diameters of the two pump arms and the cladding diameter of the input signal optical fiber is less than the inner diameter of the quartz tube. The input signal optical fiber located in the quartz tube has a clearance fit with its adjacent multiple pump arms, and the multiple pump arms have a clearance fit with the inner wall of the quartz tube.

4. The pump recovery device according to claim 1, wherein Both the input signal optical fiber and the output signal optical fiber are double - clad passive optical fibers or double - clad polarization - maintaining passive optical fibers. The working bands of the input signal optical fiber and the output signal optical fiber both include any one of the 1.0 µm band, 1.5 µm band, and 2.0 µm band.

5. A method for preparing a pump recovery device according to any one of claims 1 to 4, characterized in that, The method includes the following steps: S10, axially penetrate the pump arms of the multiple pump optical fibers and the input signal optical fiber completely through the optical fiber fixture and fix them in the quartz tube. S20, perform a fused biconical taper treatment on the pump arms inserted into the quartz tube, a part of the input signal optical fiber inserted into the quartz tube, and a part of the quartz tube to obtain the optical fiber taper part. S30, cut a part of the optical fiber taper part, axially oppose one end of the optical fiber taper part away from the optical fiber fixture to the output signal optical fiber and fusion - splice it with the output signal optical fiber.

6. The preparation method of the pump recovery device according to claim 5, wherein, In the S10 step, before inserting the pump arm and the input signal optical fiber into the quartz tube, it further includes: removing the coating layers of the pump arm and the input signal optical fiber respectively.

7. The preparation method of the pump recovery device according to claim 6, characterized in that After removing the coating layer of the pump arm and before inserting the pump arm into the quartz tube, it further includes: performing a taper treatment on the pump arm to reduce the cladding diameter of the pump arm.

8. The preparation method of the pump recovery device according to claim 6, characterized in that, After removing the coating layer of the input signal optical fiber and before inserting the input signal optical fiber into the quartz tube, it further includes: performing a cladding etching treatment on the input signal optical fiber, and the cladding etching method is hydrofluoric acid treatment.

9. The preparation method of the pump recovery device according to claim 5, characterized in that, In the step S30: The cutting angle of the fiber taper is within 1.5°.

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