All-fiber structure laser amplifier of multi-core fiber

Abstract

The invention discloses an all-fiber structure laser amplifier of a multi-core optical fiber, and relates to the technical field of optical systems.The laser amplifier comprises an injection optical fiber, a beam splitting waveguide, a phase controller, an amplifying device, a beam combining waveguide and an end cap, the injection optical fiber is used for enabling input laser to be injected into the beam splitting waveguide to form a beam splitting laser array, and the phase controller is used for controlling the phase controller; after being subjected to phase control by the phase controller, the beam splitting laser array is transmitted to the amplification device for amplification processing; the amplifying device outputs the amplified laser array to the beam combining waveguide, and the beam combining waveguide synthesizes the amplified laser array to obtain combined laser; and after the combined laser is expanded by the end cap, output laser is generated. By applying the scheme provided by the embodiment of the invention, the stability of the laser amplification process can be improved.

Description

Technical Field

[0001] This application relates to the field of optical system technology, and in particular to an all-fiber laser amplifier with a multi-core fiber structure. Background Technology

[0002] High-power fiber lasers, with their outstanding advantages such as high efficiency, excellent beam quality, excellent thermal management capabilities, and compact structure, have been widely used in industrial processing, national defense and security, scientific research, and medical aesthetics. However, the inherent slender waveguide structure of traditional single-core optical fibers, along with physical effects such as transverse mode instability, jointly restrict the further improvement of the output power of single-fiber lasers, thus creating a bottleneck in their development.

[0003] In related technologies, multi-core optical fibers have been developed to overcome the aforementioned power limits. Multi-core optical fibers can significantly increase the effective mode field area, thereby directly reducing power density and effectively suppressing nonlinear effects. Simultaneously, the distributed amplification architecture disperses the heat load across multiple cores, significantly improving heat dissipation efficiency and mitigating performance degradation caused by thermal effects. In terms of fabrication technology, multi-core optical fibers exhibit significant simplicity and cost-effectiveness.

[0004] In existing amplification architectures, multi-core fiber amplifiers based on beam splitters employ a spatially structured beam splitter and combiner to split the input laser beam and enhance the brightness of the output beam array from the multi-core fiber. The beam splitter system consists of a total reflection mirror and regional partial reflection mirrors. When incident light enters the first partial reflection mirror, a portion is transmitted to form beam 1, and a portion is reflected back to the total reflection mirror. After reflection, the light enters the second partial reflection mirror, where another portion is transmitted to form beam 2, and a portion is reflected back to the total reflection mirror. This process is repeated to split the light into 1×N beams. These 1×N beams are then injected into a second set of total reflection mirrors and regional partial reflection mirrors placed perpendicularly to the first set. The 1×N beams then form an N×N laser array. The laser array is amplified by injecting it into a square array of multi-core gain fibers. After amplification, the beams are combined by the beam splitter and combined before output. The beam splitter and combiner system consists of a total reflection mirror and regional partial reflection mirrors. Each column of the laser array has N incident beams. When the first incident beam enters the anti-reflection region of the partial reflector, it is reflected by the total reflection mirror and then enters the first partial reflection region of the partial reflector. Part of the light is reflected and part is transmitted. The second incident beam enters the first partial reflection region of the partial reflector. Part of the light is reflected and part is transmitted. The reflected light of the second beam interferes with the transmitted light of the first beam. When the two beams are out of phase, they coherently cancel each other out, and the two beams are coherently combined. By continuously repeating the above beam combining process, 1×N beam combining is achieved. For an N×N square array beam, a set of total reflection mirrors and partial reflectors can combine N×N beams into a 1×N beam. Then, by using a second set of total reflection mirrors and partial reflectors placed perpendicular to the first set of total reflection mirrors and partial reflectors, a single laser beam can be combined.

[0005] This method involves multiple separate spatial optical elements, resulting in a complex optical path and difficult adjustment, which is not conducive to the practical application of the method and leads to low stability. Summary of the Invention

[0006] The purpose of this application is to provide a multi-core fiber all-fiber laser amplifier that can improve the stability of the laser amplification process.

[0007] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides an all-fiber laser amplifier with a multi-core optical fiber structure. The laser amplifier includes an injection fiber, a beam splitter waveguide, a phase controller, an amplification device, a beam combiner waveguide, and an end cap. The injection fiber is used to inject the input laser into the beam-splitting waveguide to form a beam-splitting laser array. The beam-splitting laser array is phase-controlled by a phase controller and then transmitted to the amplification device for amplification. The amplified laser array is output from the amplification device to the beam combining waveguide, which combines the amplified laser array to obtain a beam combining laser; the beam combining laser is expanded by the end cap to generate the output laser.

[0008] In one embodiment, the laser amplifier further includes a high-reflection mirror and a phase adjustment module; The combined laser beam is expanded by the end cap to generate the target laser beam, the target laser beam is reflected by the high-reflection mirror to form the output laser beam, and the target laser beam is transmitted through the high-reflection mirror to form the sampling laser beam; The phase adjustment module is used to obtain the phase difference information of the beam splitting laser array based on the sampled laser, and adjust the phase change parameters of the phase controller based on the phase difference information.

[0009] In one embodiment, the phase adjustment module includes: a detector and a control circuit; The detector obtains an electrical signal containing phase difference information based on the sampling laser, and inputs the electrical signal into the control circuit; the control circuit is used to generate a control signal based on the electrical signal, and send the control signal to the phase controller to adjust the phase change parameters of the phase controller.

[0010] In one embodiment, the amplification device includes a forward-pumped beam combiner, a first pump laser, a backward-pumped signal beam combiner, and a second pump laser. The amplification device performs amplification in the following manner: The split laser array is transmitted to the phase controller and then injected into the forward pump combiner after being phase-controlled; the first pump laser outputs a first pump laser, which is injected into the forward pump combiner; the forward pump signal combiner injects the split laser array and the first pump laser into the gain multi-core fiber, thereby amplifying the split laser array. The second pump laser outputs a second pump laser, which is then injected into the gain multi-core fiber via the pump signal combiner, thereby amplifying the split laser array again to obtain the amplified laser array.

[0011] In one embodiment, the laser amplifier further includes: a first multi-core optical fiber, a first cladding optical stripper, and a second multi-core optical fiber; The amplified laser array is output to the beam combiner waveguide in the following manner: The amplified laser array is injected into the first multi-core fiber via the back-pump signal combiner, and then transmitted sequentially through the first multi-core fiber to the first cladding stripper and the second multi-core fiber before reaching the beam combiner waveguide.

[0012] In one embodiment, the laser amplifier further includes: a fan-in module, a third multi-core optical fiber, a second cladding optical stripper, and a fourth multi-core optical fiber; wherein the power transmission of the third multi-core optical fiber and the fourth multi-core optical fiber is less than the power transmission of the first multi-core optical fiber and the second multi-core optical fiber. The beam-splitting laser array transmits the amplification device in the following manner: After being phase-controlled by a phase controller, the beam-splitting laser array is injected into the third multi-core optical fiber through the fan-in module. The laser is then transmitted sequentially through the third multi-core optical fiber to the second cladding stripper and the fourth multi-core optical fiber before reaching the amplification device.

[0013] In one embodiment, the core diameter of the third multi-core optical fiber is one-third of the core spacing.

[0014] In one embodiment, the effective waveguide size W1 of the beam combiner waveguide is: Where 'a' represents the core diameter of the third multi-core optical fiber; and the length of the combining waveguide is 'n'. / Nλ; λ is the input laser wavelength, N represents the number of columns of the beam splitting laser array; nc represents the waveguide cladding refractive index of the beam combining waveguide; σ represents a preset correction coefficient.

[0015] In one embodiment, the effective waveguide size W of the beam splitter waveguide is: Wherein, the cross-sectional side length of the beam splitter waveguide is set to W0, and the length of the beam splitter waveguide is n. / Nλ, where n is the optical refractive index of the waveguide material constituting the beam splitter, λ is the input laser wavelength, N represents the number of columns of the beam splitter laser array, nc represents the refractive index of the waveguide cladding of the beam splitter, and σ represents a preset correction coefficient.

[0016] In one embodiment, the beam splitter waveguide is a self-imaging beam splitter waveguide, and the beam combiner waveguide is a self-imaging beam combiner waveguide.

[0017] According to the specific embodiments provided in this application, the following technical effects are disclosed: In the solution provided by this invention, after laser input is achieved through injected optical fiber, the laser beam is split before amplification and then combined after amplification using a beam-splitting waveguide and a beam-combining waveguide to obtain the amplified output laser. This effectively improves laser power, avoids the need for multiple total reflection mirrors and partial reflection mirrors, simplifies the complexity of the optical path, makes the laser amplifier structure compact and easy to adjust, and reduces interference factors in the optical path. Furthermore, the beam-splitting waveguide is connected to a phase controller, which adjusts the phase of the split beams to ensure phase consistency before amplification. The amplified laser array is then combined using the beam-combining waveguide, resulting in a stable phase of the combined output laser and reducing the impact of dispersion effects, thus ensuring the quality of the combined single-beam laser. Additionally, the beam-combining waveguide is connected to an end cap, whose beam-expanding effect reduces the power density of the combined laser, preventing excessive energy and eliminating the high-power output interface of the multi-fiber core, thereby reducing the risk of equipment damage and further ensuring stable operation. Therefore, the above-mentioned laser amplifier can improve the stability of the laser amplification process. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of an all-fiber laser amplifier with a multi-core optical fiber provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a first type of laser amplification scenario provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a second type of laser amplification scenario provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of a third type of laser amplification scenario provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the fourth type of laser amplification scenario provided in the embodiments of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] In one embodiment of the present invention, see Figure 1 A multi-core fiber all-fiber laser amplifier is provided, comprising an injection fiber 1, a beam splitter waveguide 2, a phase controller 4, an amplification device, a beam combiner waveguide 20, and an end cap 21, wherein... The injection fiber 1 is used to inject the input laser into the beam splitter waveguide 2 to form a beam splitter laser array. After the beam splitter laser array is phase controlled by the phase controller 4, it is transmitted to the amplification device for amplification. The amplified laser array output by the amplification device is sent to the beam combiner waveguide 20. The beam combiner waveguide 20 combines the amplified laser array to obtain the beam combiner laser. After the beam combiner laser is expanded by the end cap 21, the output laser is generated.

[0023] Among them, beam splitter waveguide 2 is a rectangular waveguide with a square cross-section.

[0024] In one embodiment, the effective waveguide size W of the beam splitter waveguide 2 is: The cross-sectional side length of the beam splitter waveguide is set to W0, and the length of the beam splitter waveguide is n. / Nλ, where n is the optical refractive index of the waveguide material constituting the beam splitter, λ is the input laser wavelength, and N represents the number of columns in the beam splitter array. For example, a beam splitter array with 4 columns... If the array is 4, then N=4.

[0025] nc represents the refractive index of the waveguide cladding of the beam splitter; σ represents the preset correction coefficient. Specifically, σ can be set to 0 for TE (Transverse Electric) polarization and 1 for TM (Transverse Magnetic) polarization.

[0026] After the input laser enters beam splitter waveguide 2, it undergoes mode-field coupling, energy distribution, and interference within the beam splitter waveguide 2 via a Y-branch, directional coupler, or multimode interference structure. This distributes the optical power evenly or proportionally to different output waveguides, thereby forming an N-mode beam splitter. N-beam split laser array.

[0027] The beam splitter waveguide 2 and the phase controller 4 are connected via a transmission fiber 3. The phase controller performs phase control on the spot formed by each laser beam in the beam splitter laser array. Specifically, it can detect the phase error of the beam splitter laser, extract the phase error through methods such as phase-locked loop, mixer + low-pass filter, and quadrature demodulation, and use a PID algorithm to calculate and adjust the phase of the beam splitter laser by adjusting the control voltage to achieve phase control. This ensures that a stable single laser beam is formed after beam combining.

[0028] After phase control, the beam splitting laser array is injected into the transmission fiber 5 of the fan-in module. The fan-in module 6 injects the laser signal in the transmission fiber 5 into the core of the N×N core third multi-core fiber 7. The number of cores is the same as the number of beams in the beam splitting laser array.

[0029] Fan-in module 6 serves as a coupling and docking mechanism, used to connect N... The N-beam split laser array is connected to the input end of a multi-core optical fiber. The specific transmission structure of the fan-in module is described in the following embodiment, and will not be detailed here.

[0030] In one embodiment of the present invention, the amplification device includes a forward-pumped beam combiner 12, a first pump laser 10, a backward-pumped signal beam combiner 14, and a second pump laser 16. The amplification device performs amplification processing in the following manner: After the split laser array is transmitted to the phase controller 4 and is phase-controlled, it is injected into the forward pump combiner 12; the first pump laser 10 outputs the first pump laser, which is injected into the forward pump combiner 12; the forward pump signal combiner 12 injects the split laser array and the first pump laser into the gain multi-core fiber 13, thereby amplifying the split laser array. The second pump laser 16 outputs a second pump laser, which is injected into the gain multi-core fiber 13 through the back-pump signal combiner 14, so that the split laser array is amplified again to obtain an amplified laser array.

[0031] Figure 1 Fiber 11 and fiber 15 are pump transmission fibers. The forward pump signal combiner 12 injects the beam-splitting laser array and the first pump laser together into the gain multi-core fiber 13 doped with rare-earth particles, so that the first pump laser is extracted and the signal laser is amplified. Specifically, the rare-earth particles acquire the pump laser energy and store it, and then transfer the energy to the beam-splitting laser array through stimulated emission, thereby achieving amplification.

[0032] Gain multi-core fiber refers to a special type of fiber that integrates multiple gain cores within the same fiber, enabling simultaneous amplification of multiple optical signals. Its core function is to combine "multi-core parallel transmission" with "optical amplification" into one.

[0033] The second pump laser amplifies the split laser array again in a manner similar to that of the first pump laser.

[0034] The laser amplifier also includes: a first multi-core fiber 17, a first cladding optical stripper 18, and a second multi-core fiber 19; After obtaining the amplified laser array, the amplified laser array is injected into the first multi-core fiber through the back-pump signal combiner 14, and then transmitted sequentially through the first multi-core fiber 17 to the first cladding optical stripper 18 and the second multi-core fiber 19 before reaching the beam combiner waveguide.

[0035] The cladding stripper 18, installed on the amplified transmission path, can remove residual pump laser and cladding signal light, thereby improving the quality of the laser beam after beam combining.

[0036] Referring to the foregoing embodiments, the line where the fan-in module 6 is located is provided with: fan-in module 6, third multi-core optical fiber 7, second cladding optical stripper 8, and fourth multi-core optical fiber 9; wherein, the power transmission power of the third multi-core optical fiber and the fourth multi-core optical fiber is less than the power transmission power of the first multi-core optical fiber and the second multi-core optical fiber. The beam-splitting laser array transmits the amplification device in the following manner: After being phase-controlled by phase controller 4, the beam splitting laser array is injected into the third multi-core fiber 7 through fan-in module 6. It is then transmitted sequentially through the third multi-core fiber 7 to the second cladding stripper 8 and the fourth multi-core fiber 9 before reaching the amplification device.

[0037] Compared to the first multi-core fiber 17 and the second multi-core fiber 19, the third multi-core fiber 7 and the fourth multi-core fiber 9 are low-power energy transmission multi-core fibers. Before laser amplification, low-power energy transmission is used to reduce equipment damage.

[0038] Similar to the first cladding light stripper 18 mentioned above, the second cladding light stripper 8 processes the split laser array, which can improve the quality of the split laser in the array.

[0039] In contrast, the first multi-core fiber 17 and the second multi-core fiber 19 are high-power energy-transmitting multi-core fibers, which are beneficial to improving the tolerance to high-power pump lasers after processing by the amplification device.

[0040] The N×N high-power laser beams in the second multi-core fiber 19 are finally injected into the beam combiner waveguide 20. Specifically, the beam splitter waveguide can be a self-imaging beam splitter waveguide, and the beam combiner waveguide can be a self-imaging beam combiner waveguide. That is, by utilizing the self-imaging effect (Tab effect) of the multimode waveguide, multiple coherent beams are interfered and superimposed in the waveguide, and finally a single laser beam is output.

[0041] The beam combiner waveguide 20 is a rectangular waveguide with a square cross-section. Following the previous embodiment, the side length of the square cross-section is 3a(N-1)+a. Wherein, a is the core diameter of the third multi-core fiber 7 and the fourth multi-core fiber 9.

[0042] The effective waveguide size W1 of the bundled waveguide is: Where 'a' represents the core diameter of the third multi-core fiber; and the length of the combining waveguide is 'n'. / Nλ; λ is the input laser wavelength, N represents the number of columns in the beam splitter laser array; nc represents the waveguide cladding refractive index of the beam combiner waveguide; σ represents the preset correction coefficient, which is the same as the σ set when calculating the beam splitter waveguide.

[0043] After combining, the combined laser beam is expanded by the end cap 21, reducing the laser power density at the end face before being output into free space. Specifically, the end cap can be controlled to reduce the optical power per unit area by increasing the cross-sectional area of ​​the combined laser beam while keeping the total power constant. This can be achieved by using a lens group consisting of concave and convex lenses in the end cap to magnify the diameter of the combined laser beam.

[0044] In the solution provided by this invention, after laser input is achieved through injected optical fiber, the laser beam is split before amplification and then combined after amplification using a beam-splitting waveguide and a beam-combining waveguide to obtain the amplified output laser. This effectively improves laser power, avoids the need for multiple total reflection mirrors and partial reflection mirrors, simplifies the complexity of the optical path, makes the laser amplifier structure compact and easy to adjust, and reduces interference factors in the optical path. Furthermore, the beam-splitting waveguide is connected to a phase controller, which adjusts the phase of the split beams to ensure phase consistency before amplification. The amplified laser array is then combined using the beam-combining waveguide, resulting in a stable phase of the combined output laser and reducing the impact of dispersion effects, thus ensuring the quality of the combined single-beam laser. Additionally, the beam-combining waveguide is connected to an end cap, whose beam-expanding effect reduces the power density of the combined laser, preventing excessive energy and eliminating the high-power output interface of the multi-fiber core, thereby reducing the risk of equipment damage and further ensuring stable operation. Therefore, the above-mentioned laser amplifier can improve the stability of the laser amplification process.

[0045] On the other hand, the laser amplifier mentioned above uses an all-fiber structure for transmission, which can eliminate the fiber-air interface. Since the bulk damage threshold of optical fiber is much higher than the surface damage threshold, the all-fiber structure has a lower risk of damage and can significantly increase the output power of the laser amplifier system. For a 30-micron diameter spot, the output power can be increased from kW to MW, which greatly improves the processing efficiency and quality of laser equipment and reduces operating costs.

[0046] In one embodiment, the core diameter of the third multi-core fiber is one-third of the core spacing. If the diameter of the third multi-core fiber is 'a', then the spacing between the cores is set to 3a. By setting a larger spacing, power coupling between the cores can be eliminated.

[0047] In one embodiment of the present invention, the laser amplifier further includes a high-reflection mirror 23 and a phase adjustment module; The combined laser beam is expanded by the end cap 21 to generate the target laser 22. The target laser 22 is reflected by the high-reflection mirror to form the output laser 24, and the target laser 22 is transmitted through the high-reflection mirror to form the sampling laser 25. The phase adjustment module is used to obtain the phase difference information of the beam splitting laser array based on the sampling laser 25, and adjust the phase change parameters of the phase controller based on the phase difference information.

[0048] Among them, a high-reflectivity mirror refers to a mirror with a reflectivity higher than a preset reflectivity threshold. A high-reflectivity mirror is a mirror with extremely high reflectivity for laser wavelengths, almost impermeable and non-absorbent, retaining only a small amount of transmission, and the projected portion forms the aforementioned sampling laser 25.

[0049] The phase difference between split laser beams is affected by the optical path length, which is calculated as refractive index × length. Therefore, a phase controller adjusts the refractive index or length to change the phase difference between the beams, achieving phase-locked looping. Thus, the phase change parameter can be either the refractive index or the length. This allows the phase difference to be determined based on existing phase difference information, controlling the magnitude of the optical path change and ensuring greater phase consistency among the split laser beams, achieving phase-locking. Furthermore, by acquiring phase difference information each time, the change in phase difference can be monitored in real time, thereby improving the accuracy of phase control.

[0050] Specifically, the phase adjustment module includes: detector 26 and control circuit 28; The detector 26 obtains an electrical signal containing phase difference information based on the sampled laser, and inputs the electrical signal into the control circuit 28; the control circuit 28 is used to generate a control signal based on the electrical signal and send the control signal to the phase controller to adjust the phase change parameters of the phase controller.

[0051] Specifically, phase difference information can be directly determined through the alternating current component and amplitude variation in the electrical signal. Figure 1 In the diagram, cable 27 is the transmission cable for the electrical signal input control circuit, and cable 29 is the signal output cable. The control signal can be generated using an electrical signal as input through a PID algorithm.

[0052] In related technologies, when using a beam splitter for beam splitting, if the phase-locked control system loses its lock due to external disturbances, the beam splitter combining system will generate a large amount of stray light, potentially damaging the system or even the laser equipment. However, according to the solution provided in this invention, the phase controller can be adjusted in real time to lock the phase during laser output, thereby resisting interference from external conditions and further improving system stability. This enables the laser amplifier to operate stably under complex and harsh conditions such as industrial processing and equipment manufacturing.

[0053] The following is an example of a specific implementation method to obtain the amplified output laser.

[0054] In this embodiment, an input laser beam of 1064 nm is injected into a self-imaging beam splitter waveguide 2 through an injection fiber 1 with a core diameter of 20 μm and a numerical aperture of 0.06, forming a beam as shown in the image. Figure 2 The image shows the spot size of a single laser beam. The self-imaging beam splitter waveguide 2 has a cross-sectional dimension of 320 μm, a rectangular waveguide length of 3.12 cm, a waveguide refractive index of 1.45, and a waveguide cladding refractive index of 1.4332. It splits the input laser beam into a 4×4 beam array, corresponding to a 4×4 square spot array, where each spot is 20 μm in size. Figure 3 As shown, in the beam-splitting laser array, the beams are injected into the transmission fiber 3, and after the phase of each beam is controlled by the phase controller 4, they are injected into the fan-in module 6. The fan-in module 6 accurately injects the laser signal in the transmission fiber 5 into the core of the 4×4 core low-power multi-core fiber 7. The core diameter of the multi-core fiber is 20μm, and the spacing between the cores is 60μm to eliminate power coupling between the cores.

[0055] A 4×4 laser beam from the low-power multi-core fiber 7 is injected into the low-power multi-core fiber 9 after passing through the cladding light stripper 8, and then into the forward pump signal combiner 12. Simultaneously, the pump laser 10 also enters the forward pump signal combiner 12 via the pump transmission fiber 11. The forward pump signal combiner 12 injects both the signal laser and the pump laser into the rare-earth-doped gain multi-core fiber 13, thus extracting the pump laser and amplifying the signal laser. The pump laser 16 passes through the pump transmission fiber 15 and enters the backward pump signal combiner 14, further enhancing the pump amplification capability of the system. Finally, the amplified signal light is injected into the high-power multi-core fiber 17 via the backward pump signal combiner 14. After the cladding light stripper 18 removes the residual pump light and cladding signal light, it is injected into the high-power multi-core fiber 19.

[0056] The 4×4 high-power laser beams in the high-power multi-core fiber 19 are ultimately injected into the self-imaging beam combiner waveguide 20, and the beam spot array before beam combining is as follows: Figure 4As shown. The self-imaging beam combining waveguide 20 is a rectangular waveguide with a square cross-section. The side length of the square cross-section is 240 μm, and the length of the rectangular waveguide is 2.01 cm. The target laser 22 output from the end cap 21 is incident on the high-reflection mirror 23. The high-reflection mirror 23 reflects the laser to become the system output laser 24, and the transmitted laser becomes the sampling laser 25. The sampling laser 25 is incident on the detector 26. The detector 26 converts the optical signal into an electrical signal, which is then input to the active control circuit 28 via the signal input cable 27. The active control circuit 28 runs a control algorithm to obtain a control signal, which is applied to the phase controller 4 via the signal output cable 29 for phase control. After phase locking, coherent combining is achieved, and the beam combining result is as shown. Figure 5 As shown.

[0057] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0058] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A multi-core fiber all-fiber laser amplifier, characterized in that, The laser amplifier includes an injection fiber, a beam splitter waveguide, a phase controller, an amplification device, a beam combiner waveguide, and an end cap, wherein... The injection fiber is used to inject the input laser into the beam-splitting waveguide to form a beam-splitting laser array. The beam-splitting laser array is phase-controlled by a phase controller and then transmitted to the amplification device for amplification. The amplified laser array is output from the amplification device to the beam combining waveguide, which combines the amplified laser array to obtain a beam combining laser; the beam combining laser is expanded by the end cap to generate the output laser.

2. The laser amplifier according to claim 1, characterized in that, The laser amplifier also includes a high-reflection mirror and a phase adjustment module; The combined laser beam is expanded by the end cap to generate the target laser beam, the target laser beam is reflected by the high-reflection mirror to form the output laser beam, and the target laser beam is transmitted through the high-reflection mirror to form the sampling laser beam; The phase adjustment module is used to obtain the phase difference information of the beam splitting laser array based on the sampled laser, and adjust the phase change parameters of the phase controller based on the phase difference information.

3. The laser amplifier according to claim 2, characterized in that, The phase adjustment module includes: a detector and a control circuit; The detector obtains an electrical signal containing phase difference information based on the sampling laser, and inputs the electrical signal into the control circuit; the control circuit is used to generate a control signal based on the electrical signal, and send the control signal to the phase controller to adjust the phase change parameters of the phase controller.

4. The laser amplifier according to claim 1, characterized in that, The amplification device includes a forward-pumped beam combiner, a first pump laser, a backward-pumped signal beam combiner, and a second pump laser. The amplification device performs amplification in the following manner: The split laser array is transmitted to the phase controller and then injected into the forward pump combiner after being phase-controlled; the first pump laser outputs a first pump laser, which is injected into the forward pump combiner; the forward pump signal combiner injects the split laser array and the first pump laser into the gain multi-core fiber, thereby amplifying the split laser array. The second pump laser outputs a second pump laser, which is then injected into the gain multi-core fiber via the pump signal combiner, thereby amplifying the split laser array again to obtain the amplified laser array.

5. The laser amplifier according to claim 4, characterized in that, The laser amplifier further includes: a first multi-core optical fiber, a first cladding optical stripper, and a second multi-core optical fiber; The amplified laser array is output to the beam combiner waveguide in the following manner: The amplified laser array is injected into the first multi-core fiber via the back-pump signal combiner, and then transmitted sequentially through the first multi-core fiber to the first cladding stripper and the second multi-core fiber before reaching the beam combiner waveguide.

6. The laser amplifier according to claim 5, characterized in that, The laser amplifier further includes: a fan-in module, a third multi-core fiber, a second cladding optical stripper, and a fourth multi-core fiber; wherein the energy transmission power of the third multi-core fiber and the fourth multi-core fiber is less than the energy transmission power of the first multi-core fiber and the second multi-core fiber. The beam-splitting laser array transmits the amplification device in the following manner: After being phase-controlled by a phase controller, the beam-splitting laser array is injected into the third multi-core optical fiber through the fan-in module. The laser is then transmitted sequentially through the third multi-core optical fiber to the second cladding stripper and the fourth multi-core optical fiber before reaching the amplification device.

7. The laser amplifier according to claim 6, characterized in that, The core diameter of the third multi-core optical fiber is one-third of the core spacing.

8. The laser amplifier according to claim 7, characterized in that, The effective waveguide size W1 of the beam combiner waveguide is: Where 'a' represents the core diameter of the third multi-core optical fiber; and the length of the combining waveguide is 'n'. / Nλ; λ is the input laser wavelength, N represents the number of columns of the beam splitting laser array; nc represents the waveguide cladding refractive index of the beam combining waveguide; σ represents a preset correction coefficient.

9. The laser amplifier according to claim 1, characterized in that, The effective waveguide size W of the beam splitter waveguide is: Wherein, the cross-sectional side length of the beam splitter waveguide is set to W0, and the length of the beam splitter waveguide is n. / Nλ, where n is the optical refractive index of the waveguide material constituting the beam splitter, λ is the input laser wavelength, N represents the number of columns of the beam splitter laser array, nc represents the refractive index of the waveguide cladding of the beam splitter, and σ represents a preset correction coefficient.

10. The laser amplifier according to claim 1, characterized in that, The beam splitter waveguide is a self-imaging beam splitter waveguide, and the beam combiner waveguide is a self-imaging beam combiner waveguide.

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