Fiber laser

Abstract

The application discloses a fiber laser, which comprises a seed source for outputting seed light, N-stage fiber pre-amplification circuits, and a gain crystal connected with the output of the Nth-stage fiber pre-amplification circuit among the N-stage fiber pre-amplification circuits, wherein the gain crystal is used for gain amplifying the laser output by the Nth-stage fiber pre-amplification circuit to obtain target laser and output the target laser.

Description

Technical Field

[0001] This application relates to the field of lasers, and more specifically, to a fiber laser. Background Technology

[0002] With the continuous development of laser technology, lasers have been widely applied in many fields, such as autonomous vehicles, where the installation of lidar has greatly compensated for the shortcomings of millimeter-wave radar and cameras, improving driving safety; and in the field of surveying and mapping, 3D laser scanning technology has been widely used. As the demand for lasers increases, higher requirements are being placed on improving the gain amplification of lasers.

[0003] In existing technologies, when amplifying laser gain, such as increasing the output power, nonlinear effects are easily generated. These nonlinear effects primarily affect the laser beam quality. The stronger the nonlinear effect, the worse the laser output beam quality, leading to a lower signal-to-noise ratio. Consequently, the energy distribution of the laser becomes excessively dispersed, failing to achieve a focusing effect and thus failing to meet practical applications. This, in turn, limits the extent to which the laser output power can be amplified.

[0004] There is still no effective solution to the problem of low laser gain amplification in related technologies. Summary of the Invention

[0005] This application provides a fiber laser to at least address the problem of low laser gain amplification in related technologies.

[0006] According to one embodiment of this application, a fiber laser is provided, comprising: a seed source for outputting seed light; an N-stage fiber pre-amplification circuit, wherein each stage of the N-stage fiber pre-amplification circuit includes a gain fiber, the input of the first stage fiber pre-amplification circuit is connected to the seed source, the gain fiber in the first stage fiber pre-amplification circuit is used to amplify the seed light, the input of the i-th stage fiber pre-amplification circuit is connected to the output of the (i-1)-th stage fiber pre-amplification circuit, the gain fiber in the i-th stage fiber pre-amplification circuit is used to amplify the laser output by the (i-1)-th stage fiber pre-amplification circuit, where N is a positive integer greater than or equal to 2, and 2≤i≤N; and a gain crystal connected to the output of the N-th stage fiber pre-amplification circuit, the gain crystal being used to amplify the laser output by the N-th stage fiber pre-amplification circuit to obtain and output a target laser.

[0007] Optionally, each stage of the N-stage fiber pre-amplification circuit further includes a wavelength division multiplexer and a pump source. In each stage, the input of the wavelength division multiplexer is connected to the output of the pump source, and the output of the wavelength division multiplexer is connected to the input of the gain fiber. Specifically, the input of the wavelength division multiplexer in the first-stage fiber pre-amplification circuit is connected to the seed source. The wavelength division multiplexer in the first-stage fiber pre-amplification circuit couples the seed light and the pump light output from the pump source in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser light. The gain fiber in the first-stage fiber pre-amplification circuit is used to amplify the gain of the coupled laser output from the wavelength division multiplexer in the first-stage fiber pre-amplification circuit; the wavelength division multiplexer in the i-th-stage fiber pre-amplification circuit is used to couple the laser output from the (i-1)-th-stage fiber pre-amplification circuit with the pump light output from the pump source in the i-th-stage fiber pre-amplification circuit to obtain and output the coupled laser; the gain fiber in the i-th-stage fiber pre-amplification circuit is used to amplify the gain of the coupled laser output from the wavelength division multiplexer in the i-th-stage fiber pre-amplification circuit.

[0008] Optionally, each stage of the N-stage fiber pre-amplification circuit further includes an optical isolator. In each stage of the fiber pre-amplification circuit, the output of the gain fiber is connected to the input of the optical isolator, and the output of the optical isolator is the output of each stage of the fiber pre-amplification circuit. The optical isolator is used to isolate the gain-amplified laser output from the gain fiber, thereby obtaining and outputting the isolated laser.

[0009] Optionally, the direction of the pump light output from the pump source in the first-stage fiber pre-amplification circuit is the same as the direction of the seed light output from the seed source; the direction of the pump light output from the pump source in the i-th-stage fiber pre-amplification circuit is the same as the direction of the laser output from the (i-1)-th-stage fiber pre-amplification circuit.

[0010] Optionally, each stage of the N-stage fiber pre-amplification circuit further includes a wavelength division multiplexer and a pump source. In each stage, the input of the wavelength division multiplexer is connected to the output of the pump source, and the input of the wavelength division multiplexer is connected to the output of the gain fiber. Specifically, the input of the gain fiber in the first-stage fiber pre-amplification circuit is connected to the seed source. The gain fiber in the first-stage fiber pre-amplification circuit is used to amplify the seed light output from the seed source. The wavelength division multiplexer in the first-stage fiber pre-amplification circuit is used to pre-amplify the first-stage fiber. The amplified laser output from the gain fiber in the large circuit is coupled with the pump light output from the pump source in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. The gain fiber in the i-th-stage fiber pre-amplification circuit is used to amplify the laser output from the (i-1)-th-stage fiber pre-amplification circuit. The wavelength division multiplexer in the i-th-stage fiber pre-amplification circuit is used to couple the amplified laser output from the gain fiber in the i-th-stage fiber pre-amplification circuit with the pump light output from the pump source in the i-th-stage fiber pre-amplification circuit to obtain and output the coupled laser.

[0011] Optionally, each stage of the N-stage fiber pre-amplification circuit further includes an optical isolator. In each stage of the fiber pre-amplification circuit, the output of the wavelength division multiplexer is connected to the input of the optical isolator. The output of the optical isolator is the output of each stage of the fiber pre-amplification circuit. The optical isolator is used to isolate the coupled laser output from the wavelength division multiplexer, thereby obtaining and outputting the isolated laser.

[0012] Optionally, the direction of the pump light output from the pump source in the first-stage fiber pre-amplification circuit is opposite to the direction of the seed light output from the seed source; the direction of the pump light output from the pump source in the i-th-stage fiber pre-amplification circuit is opposite to the direction of the laser output from the (i-1)-th-stage fiber pre-amplification circuit.

[0013] Optionally, the input current and input voltage of the seed source are electrical pulse signals, and the seed light output by the seed source is an optical pulse signal.

[0014] Optionally, the gain fiber is doped with a first rare earth element, the first rare earth element corresponding to the wavelength of the seed light; and / or, the gain crystal is doped with a second rare earth element, the second rare earth element corresponding to the wavelength of the seed light.

[0015] Optionally, the gain fiber is an erbium-doped fiber or an erbium-ytterbium co-doped fiber, and the gain crystal is an erbium-ytterbium co-doped phosphate glass.

[0016] In this embodiment, a fiber laser is provided, comprising: a seed source for outputting seed light; and an N-stage fiber pre-amplification circuit, wherein each stage of the N-stage fiber pre-amplification circuit includes a gain fiber. The input of the first-stage fiber pre-amplification circuit is connected to the seed source, and the gain fiber in the first-stage fiber pre-amplification circuit amplifies the seed light. The input of the i-th stage fiber pre-amplification circuit is connected to the output of the (i-1)-th stage fiber pre-amplification circuit, and the gain fiber in the i-th stage fiber pre-amplification circuit amplifies the laser output from the (i-1)-th stage fiber pre-amplification circuit. The process involves a gain amplification, where N is a positive integer greater than or equal to 2, and 2 ≤ i ≤ N. A gain crystal is connected to the output of the Nth-stage fiber pre-amplifier circuit. The gain crystal amplifies the laser output from the Nth-stage fiber pre-amplifier circuit to obtain and output the target laser. In essence, the fiber laser incorporates a gain fiber and a gain crystal. First, the seed light output from the seed source is amplified through the gain fiber, and then the laser light, after being amplified by the gain fiber, is amplified again through the gain crystal. Because the gain crystal can suppress the nonlinear effects generated by the gain fiber when the laser power is high, it can significantly improve the degree of laser gain amplification. This technical solution solves the problem of low laser gain amplification in related technologies, achieving the technical effect of improving the degree of laser gain amplification. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

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

[0019] Figure 1 This is a structural frame of a fiber laser according to an embodiment of this application. Figure 1 ;

[0020] Figure 2 This is a structural frame of a fiber laser according to an embodiment of this application. Figure 2 ;

[0021] Figure 3 This is a structural frame of a fiber laser according to an embodiment of this application. Figure 3 ;

[0022] Figure 4 This is a structural frame of a fiber laser according to an embodiment of this application. Figure 4 ;

[0023] Figure 5 This is a structural frame of a fiber laser according to an embodiment of this application. Figure 5 ;

[0024] Figure 6 This is a schematic diagram of a fiber laser according to an embodiment of this application. Figure 1 ;

[0025] Figure 7 This is a schematic diagram of a fiber laser according to an embodiment of this application. Figure 2 ;

[0026] Figure 8 This is a schematic diagram of a fiber laser according to an embodiment of this application. Figure 3 . Detailed Implementation

[0027] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0028] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0029] This application provides a fiber laser. Figure 1 This is a structural frame of a fiber laser according to an embodiment of this application. Figure 1 ,like Figure 1As shown, the aforementioned fiber laser includes: a seed source 102 for outputting seed light; and an N-stage fiber pre-amplification circuit (stage 1, stage 2, ..., stage i-1, stage i, ..., stage N), wherein each stage of the N-stage fiber pre-amplification circuit includes gain fibers (gain fiber 104_1, gain fiber 104_2, gain fiber 104_(i-1), gain fiber 104_i, ... ... The input of the first-stage fiber pre-amplifier circuit in the N-stage fiber pre-amplifier circuit is connected to the seed source. The gain fiber 104_1 in the first-stage fiber pre-amplifier circuit is used to amplify the gain of the seed light. The input of the i-th stage fiber pre-amplifier circuit in the N-stage fiber pre-amplifier circuit is connected to the output of the (i-1)-th stage fiber pre-amplifier circuit. The gain fiber 104_i in the i-th stage fiber pre-amplifier circuit is used to amplify the gain of the laser output by the (i-1)-th stage fiber pre-amplifier circuit. N is a positive integer greater than or equal to 2, and 2≤i≤N. The gain crystal 106 is connected to the output of the N-stage fiber pre-amplifier circuit in the N-stage fiber pre-amplifier circuit. The gain crystal 106 is used to amplify the gain of the laser output by the N-stage fiber pre-amplifier circuit, thereby obtaining and outputting the target laser.

[0030] The aforementioned fiber laser incorporates a gain fiber and a gain crystal. First, the seed light output from the seed source is amplified via the gain fiber. Then, the laser light, after being amplified by the gain fiber, is further amplified by the gain crystal. Since the gain crystal can suppress the nonlinear effects generated by the gain fiber when the laser power is high, the degree of laser gain amplification can be significantly improved. This technical solution solves the problem of low laser gain amplification in related technologies, achieving the technical effect of improving the degree of laser gain amplification.

[0031] In an exemplary embodiment, each stage of the N-stage fiber pre-amplification circuit further includes a wavelength division multiplexer (WDM) and a pump source. In each stage, the input of the WDM is connected to the output of the pump source, and the output of the WDM is connected to the input of the gain fiber. Specifically, the input of the WDM in the first-stage fiber pre-amplification circuit is connected to the seed source. The WDM in the first-stage fiber pre-amplification circuit couples the seed light with the pump light output from the pump source in the first-stage fiber pre-amplification circuit to obtain and output the coupled light. The laser beam after coupling is obtained by the gain fiber in the first-stage fiber pre-amplification circuit, which amplifies the gain of the coupled laser beam output from the wavelength division multiplexer in the first-stage fiber pre-amplification circuit. The wavelength division multiplexer in the i-th-stage fiber pre-amplification circuit couples the laser beam output from the (i-1)-th-stage fiber pre-amplification circuit with the pump light output from the pump source in the i-th-stage fiber pre-amplification circuit to obtain and output the coupled laser beam. The gain fiber in the i-th-stage fiber pre-amplification circuit amplifies the gain of the coupled laser beam output from the wavelength division multiplexer in the i-th-stage fiber pre-amplification circuit.

[0032] Figure 2 This is a structural frame of a fiber laser according to an embodiment of this application. Figure 2 ,like Figure 2 As shown, the aforementioned fiber laser includes: a seed source 102 for outputting seed light; and an N-stage fiber pre-amplifier circuit (stage 1, stage 2, ..., stage (i-1), stage i, ..., stage N), where N is a positive integer greater than or equal to 2, 2 ≤ i ≤ N. Each stage of the N-stage fiber pre-amplifier circuit (stage 1, stage 2, ..., stage (i-1), stage i, ..., stage N) represents a specific fiber pre-amplifier. Each path includes gain fiber (gain fiber 104_1, gain fiber 104_2, gain fiber 104_(i-1), gain fiber 104_i, ..., gain fiber 104_N, respectively), wavelength division multiplexer (wavelength division multiplexer 108_1, wavelength division multiplexer 108_2, ..., wavelength division multiplexer 108_(i-1), wavelength division multiplexer 108_i, ..., wavelength division multiplexer 108_N, respectively) and pump source (pump source 110_1, pump source 110_2, ..., pump source 110_(i-1), pump source 110_i, ..., pump source 110_N, respectively).

[0033] In each stage of the fiber preamplifier circuit, the inputs of the wavelength division multiplexers (WDM108_1, WDM108_2, ..., WDM108_(i-1), WDM108_i, ..., WDM108_N) are respectively connected to the inputs of the pump sources (pump source 110_1, pump source 110_2, ..., pump source 110_(i-1), pump source 110_i, ..., pump source 110_N). The outputs of the wavelength division multiplexers (WDM108_1, WDM108_2, ..., WDM108_(i-1), WDM108_i, ..., WDM108_N) are connected to the inputs of the gain fibers (gain fiber 104_1, gain fiber 104_2, gain fiber 104_(i-1), gain fiber 104_i, ..., gain fiber 104_N) respectively.

[0034] The input of wavelength division multiplexer 108_1 in the first-stage fiber pre-amplification circuit is connected to seed source 102. Wavelength division multiplexer 108_1 in the first-stage fiber pre-amplification circuit is used to couple the seed light and the pump light output from pump source 110_1 in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. Gain fiber 104_1 in the first-stage fiber pre-amplification circuit is used to amplify the gain of the coupled laser output from wavelength division multiplexer 108_1 in the first-stage fiber pre-amplification circuit. Wavelength division multiplexer 108_i in the i-th-stage fiber pre-amplification circuit is used to couple the laser output from the (i-1)-th-stage fiber pre-amplification circuit and the pump light output from pump source 110_i in the i-th-stage fiber pre-amplification circuit to obtain and output the coupled laser. Gain fiber 104_i in the i-th-stage fiber pre-amplification circuit is used to amplify the gain of the coupled laser output from wavelength division multiplexer 108_i in the i-th-stage fiber pre-amplification circuit.

[0035] Gain crystal 106 is connected to the output of the Nth-stage fiber pre-amplifier circuit in the Nth-stage fiber pre-amplifier circuit. Gain crystal 106 is used to amplify the laser output from the Nth-stage fiber pre-amplifier circuit to obtain and output the target laser.

[0036] Optionally, in this embodiment, the seed light output from the seed source is pre-amplified by an N-level fiber pre-amplification circuit. This allows the seed light to be amplified within a specific range first. When the required laser output power is large, this avoids directly amplifying the seed light to the required output power, thereby avoiding potential noise and improving the quality of the laser.

[0037] In an exemplary embodiment, each stage of the N-stage fiber pre-amplification circuit further includes an optical isolator. In each stage of the fiber pre-amplification circuit, the output of the gain fiber is connected to the input of the optical isolator, and the output of the optical isolator is the output of each stage of the fiber pre-amplification circuit. The optical isolator is used to isolate the gain-amplified laser output from the gain fiber, thereby obtaining and outputting the isolated laser.

[0038] Figure 3 This is a structural frame of a fiber laser according to an embodiment of this application. Figure 3 ,like Figure 3 As shown, the aforementioned fiber laser includes: a seed source 102 for outputting seed light; and an N-stage fiber pre-amplification circuit (stage 1, stage 2, ..., stage (i-1), stage i, ..., stage N), where N is a positive integer greater than or equal to 2, and 2 ≤ i ≤ N; wherein each stage of the N-stage fiber pre-amplification circuit (stage 1, stage 2, ..., stage (i-1), stage i, ..., stage N) includes gain fibers (gain fiber 104_1, gain fiber 104_2, gain fiber 104_2, ..., gain fiber 104_3, ..., gain fiber 104_4_5 ...5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_5, ..., gain fiber 104_ Optical fiber 104_(i-1), gain fiber 104_i, ..., gain fiber 104_N), wavelength division multiplexers (wavelength division multiplexer 108_1, wavelength division multiplexer 108_2, ..., wavelength division multiplexer 108_(i-1), wavelength division multiplexer 108_i, ..., wavelength division multiplexer 108_N, respectively), pump sources (pump source 110_1, pump source 110_2, ..., pump source 110_(i-1), pump source 110_i, ..., pump source 110_N, respectively), and optical isolators (optical isolators 112_1, optical isolators 112_2, ..., optical isolators 112_(i-1), optical isolators 112_i, ..., optical isolators 112_N, respectively).

[0039] In each stage of the fiber preamplifier circuit, the inputs of the wavelength division multiplexers (WDM108_1, WDM108_2, ..., WDM108_(i-1), WDM108_i, ..., WDM108_N) are respectively connected to the inputs of the pump sources (pump source 110_1, pump source 110_2, ..., pump source 110_(i-1), pump source 110_i, ..., pump source 110_N). The outputs of the wavelength division multiplexers (WDM108_1, WDM108_2, ..., WDM108_(i-1), WDM108_i, ..., WDM108_N) are connected to the inputs of the gain fibers (gain fiber 104_1, gain fiber 104_2, gain fiber 104_(i-1), gain fiber 104_i, ..., gain fiber 104_N) respectively. The outputs of the gain fibers (gain fiber 104_1, gain fiber 104_2, gain fiber 104_(i-1), gain fiber 104_i, ..., gain fiber 104_N) are connected to the inputs of the optical isolators (optical isolators 112_1, optical isolators 112_2, ..., optical isolators 112_(i-1), optical isolators 112_i, ..., optical isolators 112_N), and the outputs of the optical isolators (optical isolators 112_1, optical isolators 112_2, ..., optical isolators 112_(i-1), ..., optical isolators 112_N) are connected to the inputs of the optical isolators. The output of 12_i, ..., 112_N is the output of each stage of fiber pre-amplification circuit. Optical isolators (optical isolator 112_1, optical isolator 112_2, ..., 112_(i-1), 112_i, ..., 112_N) are used to isolate the amplified laser output from the gain fiber (gain fiber 104_1, gain fiber 104_2, gain fiber 104_(i-1), gain fiber 104_i, ..., gain fiber 104_N) to obtain and output the isolated laser.

[0040] The input of wavelength division multiplexer 108_1 in the first-stage fiber pre-amplification circuit is connected to seed source 102. Wavelength division multiplexer 108_1 in the first-stage fiber pre-amplification circuit is used to couple the seed light and the pump light output from pump source 110_1 in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. Gain fiber 104_1 in the first-stage fiber pre-amplification circuit is used to amplify the gain of the coupled laser output from wavelength division multiplexer 108_1 in the first-stage fiber pre-amplification circuit. Wavelength division multiplexer 108_i in the i-th-stage fiber pre-amplification circuit is used to couple the laser output from the (i-1)-th-stage fiber pre-amplification circuit and the pump light output from pump source 110_i in the i-th-stage fiber pre-amplification circuit to obtain and output the coupled laser. Gain fiber 104_i in the i-th-stage fiber pre-amplification circuit is used to amplify the gain of the coupled laser output from wavelength division multiplexer 108_i in the i-th-stage fiber pre-amplification circuit.

[0041] Gain crystal 106 is connected to the output of the Nth-stage fiber pre-amplifier circuit (i.e., optical isolator 112_N) in the Nth-stage fiber pre-amplifier circuit. Gain crystal 106 is used to amplify the laser output from the Nth-stage fiber pre-amplifier circuit to obtain and output the target laser.

[0042] In one exemplary embodiment, the direction of the pump light output from the pump source in the first-stage fiber pre-amplification circuit is the same as the direction of the seed light output from the seed source; the direction of the pump light output from the pump source in the i-th-stage fiber pre-amplification circuit is the same as the direction of the laser output from the (i-1)-th-stage fiber pre-amplification circuit.

[0043] In an exemplary embodiment, each stage of the N-stage fiber pre-amplification circuit further includes a wavelength division multiplexer and a pump source. In each stage, the input of the wavelength division multiplexer is connected to the output of the pump source, and the input of the wavelength division multiplexer is connected to the output of the gain fiber. The input of the gain fiber in the first-stage fiber pre-amplification circuit is connected to the seed source. The gain fiber in the first-stage fiber pre-amplification circuit is used to amplify the seed light output from the seed source. The wavelength division multiplexer in the first-stage fiber pre-amplification circuit is used to amplify the first-stage light... The amplified laser output from the gain fiber in the fiber pre-amplification circuit is coupled with the pump light output from the pump source in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. The gain fiber in the i-th-stage fiber pre-amplification circuit is used to amplify the laser output from the (i-1)-th-stage fiber pre-amplification circuit. The wavelength division multiplexer in the i-th-stage fiber pre-amplification circuit is used to couple the amplified laser output from the gain fiber in the i-th-stage fiber pre-amplification circuit with the pump light output from the pump source in the i-th-stage fiber pre-amplification circuit to obtain and output the coupled laser.

[0044] Figure 4 This is a structural frame of a fiber laser according to an embodiment of this application. Figure 4 ,like Figure 4As shown, the aforementioned fiber laser includes: a seed source 102 for outputting seed light; and an N-stage fiber pre-amplifier circuit (a first-stage fiber pre-amplifier circuit, a second-stage fiber pre-amplifier circuit, ..., an (i-1)-stage fiber pre-amplifier circuit, an i-stage fiber pre-amplifier circuit, ..., an N-stage fiber pre-amplifier circuit), where N is a positive integer greater than or equal to 2, and 2 ≤ i ≤ N. The N-stage fiber pre-amplifier circuit (a first-stage fiber pre-amplifier circuit, a second-stage fiber pre-amplifier circuit, ..., an (i-1)-stage fiber pre-amplifier circuit, an i-stage fiber pre-amplifier circuit, ..., an N-stage fiber pre-amplifier circuit) Each fiber preamplifier circuit in the path includes gain fiber (gain fiber 104_1, gain fiber 104_2, gain fiber 104_(i-1), gain fiber 104_i, ..., gain fiber 104_N), wavelength division multiplexer (wavelength division multiplexer 108_1, wavelength division multiplexer 108_2, ..., 108_(i-1), 108_i, ..., 108_N), and pump source (pump source 110_1, 110_2, ..., 110_(i-1), 110_i, ..., 110_N).

[0045] In each stage of the fiber optic pre-amplifier circuit, the inputs of the wavelength division multiplexers (WDM108_1, WDM108_2, ..., WDM108_(i-1), WDM108_i, ..., WDM108_N) are connected to the outputs of the pump sources (pump sources 110_1, 110_2, ..., 110_(i-1), 110_i, ..., 110_N). The inputs of the multiplexers (WDM108_1, WDM108_2, ..., WDM108_(i-1), WDM108_i, ..., WDM108_N) are connected to the outputs of the gain fibers (gain fiber 104_1, gain fiber 104_2, gain fiber 104_(i-1), gain fiber 104_i, ..., gain fiber 104_N).

[0046] The input of the gain fiber 104_1 in the first-stage fiber pre-amplification circuit is connected to the seed source 102. The gain fiber 104_1 in the first-stage fiber pre-amplification circuit is used to amplify the gain of the seed light output from the seed source 102. The wavelength division multiplexer 108_1 in the first-stage fiber pre-amplification circuit is used to couple the amplified laser output from the gain fiber 104_1 in the first-stage fiber pre-amplification circuit with the pump light output from the pump source 110_1 in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. The gain fiber 104_i in the i-th-stage fiber pre-amplification circuit is used to amplify the gain of the laser output from the (i-1)-th-stage fiber pre-amplification circuit. The wavelength division multiplexer 108_i in the i-th-stage fiber pre-amplification circuit is used to couple the amplified laser output from the gain fiber 104_i in the i-th-stage fiber pre-amplification circuit with the pump light output from the pump source 110_i in the i-th-stage fiber pre-amplification circuit to obtain and output the coupled laser.

[0047] Gain crystal 106 is connected to the output of the Nth-stage fiber pre-amplifier circuit in the Nth-stage fiber pre-amplifier circuit. Gain crystal 106 is used to amplify the laser output from the Nth-stage fiber pre-amplifier circuit to obtain and output the target laser.

[0048] In an exemplary embodiment, each stage of the N-stage fiber pre-amplification circuit further includes an optical isolator. In each stage of the fiber pre-amplification circuit, the output of the wavelength division multiplexer is connected to the input of the optical isolator. The output of the optical isolator is the output of each stage of the fiber pre-amplification circuit. The optical isolator is used to isolate the coupled laser output from the wavelength division multiplexer, thereby obtaining and outputting the isolated laser.

[0049] Figure 5 This is a structural frame of a fiber laser according to an embodiment of this application. Figure 5 ,like Figure 5As shown, the aforementioned fiber laser includes: a seed source 102 for outputting seed light; and an N-stage fiber pre-amplifier circuit (stage 1, stage 2, ..., stage (i-1), stage i, ..., stage N), where N is a positive integer greater than or equal to 2, 2 ≤ i ≤ N. Each stage of the N-stage fiber pre-amplifier circuit (stage 1, stage 2, ..., stage (i-1), stage i, ..., stage N) includes a gain fiber (specifically, gain fiber 104_1). Gain fiber 104_2, gain fiber 104_(i-1), gain fiber 104_i, ..., gain fiber 104_N), wavelength division multiplexer (wavelength division multiplexer 108_1, wavelength division multiplexer 108_2, ..., wavelength division multiplexer 108_(i-1), wavelength division multiplexer 108_i, ..., wavelength division multiplexer 108_N), pump source (pump source 110_1, 110_2, ..., 110_(i-1), 110_i, ..., 110_N), and optical isolator (optical isolator 112_1, optical isolator 112_2, ..., 112_(i-1), 112_i, ..., 112_N).

[0050] In each stage of the fiber optic pre-amplifier circuit, the inputs of the wavelength division multiplexers (WDM108_1, WDM108_2, ..., WDM108_(i-1), WDM108_i, ..., WDM108_N) are connected to the outputs of the pump sources (pump sources 110_1, 110_2, ..., 110_(i-1), 110_i, ..., 110_N). The inputs of the multiplexers (WDM108_1, WDM108_2, ..., WDM108_(i-1), WDM108_i, ..., WDM108_N) are connected to the outputs of the gain fibers (gain fiber 104_1, gain fiber 104_2, gain fiber 104_(i-1), gain fiber 104_i, ..., gain fiber 104_N). The outputs of wavelength division multiplexers (WDM multiplexer 108_1, WDM multiplexer 108_2, ..., 108_(i-1), 108_i, ..., 108_N) are connected to the inputs of optical isolators (optical isolators 112_1, optical isolators 112_2, ..., optical isolators 112_(i-1), optical isolators 112_i, ..., optical isolators 112_N), and the optical isolators (optical isolators 112_1, optical isolators 112_2, ..., optical isolators 112_(i-1), optical isolators 112_N) are connected to the inputs of ...N, optical isolators 112_N). The output of optical isolators (112_1, 112_2, ..., 112_(i-1), 112_i, ..., 112_N) is the output of each stage of fiber pre-amplification circuit. Optical isolators (112_1, 112_2, ..., 112_(i-1), 112_i, ..., 112_N) are used to isolate the coupled laser output from wavelength division multiplexers (108_1, 108_2, ..., 108_(i-1), 108_i, ..., 108_N) to obtain and output the isolated laser.

[0051] The input of the gain fiber 104_1 in the first-stage fiber pre-amplification circuit is connected to the seed source 102. The gain fiber 104_1 in the first-stage fiber pre-amplification circuit is used to amplify the gain of the seed light output from the seed source 102. The wavelength division multiplexer 108_1 in the first-stage fiber pre-amplification circuit is used to couple the amplified laser output from the gain fiber 104_1 in the first-stage fiber pre-amplification circuit with the pump light output from the pump source 110_1 in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. The gain fiber 104_i in the i-th-stage fiber pre-amplification circuit is used to amplify the gain of the laser output from the (i-1)-th-stage fiber pre-amplification circuit. The wavelength division multiplexer 108_i in the i-th-stage fiber pre-amplification circuit is used to couple the amplified laser output from the gain fiber 104_i in the i-th-stage fiber pre-amplification circuit with the pump light output from the pump source 110_i in the i-th-stage fiber pre-amplification circuit to obtain and output the coupled laser.

[0052] Gain crystal 106 is connected to the output of the Nth stage fiber pre-amplifier circuit (i.e., the output of optical isolator 112_N) in the Nth stage fiber pre-amplifier circuit. Gain crystal 106 is used to amplify the laser output from the Nth stage fiber pre-amplifier circuit to obtain and output the target laser.

[0053] In one exemplary embodiment, the direction of the pump light output from the pump source in the first-stage fiber pre-amplifier circuit is opposite to the direction of the seed light output from the seed source; the direction of the pump light output from the pump source in the i-th-stage fiber pre-amplifier circuit is opposite to the direction of the laser output from the (i-1)-th-stage fiber pre-amplifier circuit.

[0054] In one exemplary embodiment, the input current and input voltage of the seed source are electrical pulse signals, and the seed light output by the seed source is an optical pulse signal.

[0055] Optionally, in this embodiment, the seed source can be, but is not limited to, a semiconductor laser with a wavelength of 1550nm or 1064nm, etc., and the output power of the seed source is 10μW to 100mW. To achieve pulsed laser output, an electrical pulse signal can be input to the input current and input voltage of the seed source, thereby outputting an optical pulse signal seed light. The seed light output by the seed source can be, but is not limited to, a laser with the same wavelength as the seed source (e.g., 1550nm or 1064nm, etc.).

[0056] In one exemplary embodiment, the gain fiber is doped with a first rare earth element, the first rare earth element corresponding to the wavelength of the seed light; and / or, the gain crystal is doped with a second rare earth element, the second rare earth element corresponding to the wavelength of the seed light.

[0057] Optionally, in this embodiment, the rare earth elements doped in the gain fiber and gain crystal can be, but are not limited to, different or the same. The rare earth element can be selected based on the wavelength of the seed light and the energy level distribution of the rare earth element, corresponding to the wavelength of the seed light. Selecting a rare earth element corresponding to the wavelength of the seed light will generate laser light of that wavelength. This is determined by the energy level structure of different rare earth elements; a certain energy level difference corresponds to a certain laser wavelength. For example, when the wavelength of the seed light is 1550 nm, the rare earth element doped in the gain fiber and gain crystal can be, but is not limited to, erbium; when the wavelength of the seed light is 1064 nm, the rare earth element doped in the gain fiber and gain crystal can be, but is not limited to, ytterbium. Gain fibers and gain crystals doped with suitable rare earth elements can be selected according to the actual requirements for seed light of different wavelengths.

[0058] In one exemplary embodiment, the gain fiber is an erbium-doped fiber or an erbium-ytterbium co-doped fiber, and the gain crystal is an erbium-ytterbium co-doped phosphate glass.

[0059] Optionally, in this embodiment, by using a hybrid gain scheme of gain fiber and gain crystal, the nonlinear effects that fiber gain is prone to cause under high power and high peak power conditions can be avoided, thereby improving the laser power enhancement efficiency as well as beam energy and quality.

[0060] To better understand the structure of the fiber laser described above, the structure of the fiber laser will be further described below in conjunction with optional embodiments, but this is not intended to limit the technical solutions of the embodiments of this application.

[0061] This embodiment provides a fiber laser. Figure 6 This is a schematic diagram of a fiber laser according to an embodiment of this application. Figure 1 ,like Figure 6 As shown, the fiber laser may include, but is not limited to, a seed source 102, a first-stage fiber pre-amplification circuit and a second-stage fiber pre-amplification circuit, and an erbium-ytterbium co-doped phosphate glass 106 (i.e., the gain crystal mentioned above). The first-stage fiber pre-amplification circuit includes a wavelength division multiplexer 1, a pump source 1, a gain fiber 1, and an optical isolator 1; the second-stage fiber pre-amplification circuit includes a wavelength division multiplexer 2, a pump source 2, a gain fiber 2, and an optical isolator 2.

[0062] In the first-stage and second-stage fiber pre-amplification circuits, the inputs of wavelength division multiplexer 1 and wavelength division multiplexer 2 are connected to the outputs of pump source 1 and pump source 2, respectively. The outputs of wavelength division multiplexer 1 and wavelength division multiplexer 2 are connected to the inputs of gain fiber 1 and gain fiber 2, respectively. The outputs of gain fiber 1 and gain fiber 2 are connected to the inputs of optical isolator 1 and optical isolator 2, respectively. The outputs of optical isolator 1 and optical isolator 2 are the outputs of the first-stage and second-stage fiber pre-amplification circuits, respectively.

[0063] The input of wavelength division multiplexer 1 in the first-stage fiber pre-amplification circuit is connected to seed source 102. Wavelength division multiplexer 1 in the first-stage fiber pre-amplification circuit is used to couple the seed light and the pump light output from pump source 1 in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. Gain fiber 1 in the first-stage fiber pre-amplification circuit is used to amplify the gain of the coupled laser output from wavelength division multiplexer 1 in the first-stage fiber pre-amplification circuit. Wavelength division multiplexer 2 in the second-stage fiber pre-amplification circuit is used to couple the laser output from the laser in the first-stage fiber pre-amplification circuit and the pump light output from pump source 2 in the second-stage fiber pre-amplification circuit to obtain and output the coupled laser. Gain fiber 2 in the second-stage fiber pre-amplification circuit is used to amplify the gain of the coupled laser output from wavelength division multiplexer 2 in the second-stage fiber pre-amplification circuit.

[0064] Erbium-ytterbium co-doped phosphate glass 106 is connected to the output of the second-stage fiber pre-amplifier circuit (i.e., the output of optical isolator 2). Erbium-ytterbium co-doped phosphate glass 106 is used to amplify the gain of the laser output from the second-stage fiber pre-amplifier circuit to obtain and output the target laser.

[0065] In detail, the seed source 102 can be, but is not limited to, a semiconductor laser with a wavelength of 1550nm, providing a seed source at 1550nm. The output power of the seed source is from 10μW to 100mW. To achieve pulsed laser output, electrical pulse signals can be input to the seed source's input current and voltage, ultimately resulting in the output of an optical pulse signal.

[0066] Pump source 1 primarily provides energy to the system to achieve population inversion. Pump source 1 can be, but is not limited to, forward pumping, resulting in a higher beam quality. This application does not limit the wavelength of the pump source. The main function of wavelength division multiplexer 1 is to couple the seed light and the pump light output from pump source 1 together for subsequent laser excitation and gain. Wavelength division multiplexer 1 couples the seed light source and pump light together in the same optical fiber via fiber optics, and then transmits them together to gain fiber 1. Gain fiber 1 can be, but is not limited to, erbium-doped fiber, and can be used, but is not limited to, to gain and amplify the laser output from the seed source. For example, it can amplify the seed light source from 1mW to 100mW, with the specific amplification factor depending on the final requirements. Alternatively, gain fiber 1 can also be erbium-ytterbium co-doped fiber, which provides a higher gain, but may introduce more noise, potentially affecting the beam quality. Optical isolator 1 can be, but is not limited to, used to prevent the returned light from damaging the preceding optical path, such as damaging the seed source. In other words, the seed light, after being amplified by the gain fiber, can only continue to propagate forward to the subsequent fiber, and cannot be transmitted backward to the seed source. This is mainly to protect the preceding devices from damage caused by the returning light. Optical isolator 1 is connected to wavelength division multiplexer 1 via optical fiber.

[0067] Wavelength division multiplexer 2 primarily couples the amplified laser output from the first-stage fiber pre-amplifier circuit with the pump light for further laser excitation and amplification. Wavelength division multiplexer 2 couples the seed source and pump source together in the same fiber, then transmits the light to the subsequent gain fiber 2. Pump source 2 primarily provides pump energy for population inversion. Pump source 2 can, but is not limited to, forward pumping, improving the output beam quality. Gain fiber 2 can, but is not limited to, be erbium-ytterbium co-doped fiber, further amplifying the laser output power. The laser power can, but is not limited to, be amplified to several W to several hundred W, depending on the specific requirements. Optical isolator 2 primarily prevents returned light from damaging the preceding optical path. Optical isolator 2 can, but is not limited to, ensuring the laser transmission direction and preventing returned light from damaging preceding optical components. Optical isolator 2 is connected to the gain fiber via optical fiber. The light is then transmitted in spatial form to the subsequent erbium-ytterbium co-doped phosphate glass.

[0068] The erbium-ytterbium co-doped phosphate glass 106 is primarily used to further amplify the laser output from the second-stage fiber pre-amplifier circuit, thereby obtaining a high-power, high-quality beam. The final laser beam is output as spatial light. By employing a hybrid gain method using both gain fiber and gain crystal, the nonlinear effects that fiber gain can easily cause at high power and high peak power conditions can be avoided, thus improving the energy and quality of the output laser.

[0069] Figure 7This is a schematic diagram of a fiber laser according to an embodiment of this application. Figure 2 ,like Figure 7 As shown, the aforementioned fiber laser may include, but is not limited to, a seed source 102, a first-stage fiber pre-amplification circuit, a second-stage fiber pre-amplification circuit, a third-stage fiber pre-amplification circuit, and an erbium-ytterbium co-doped phosphate glass 106 (i.e., the aforementioned gain crystal). The first-stage fiber pre-amplification circuit includes a wavelength division multiplexer 1, a pump source 1, a gain fiber 1, and an optical isolator 1; the second-stage fiber pre-amplification circuit includes a wavelength division multiplexer 2, a pump source 2, a gain fiber 2, and an optical isolator 2; and the third-stage fiber pre-amplification circuit includes a wavelength division multiplexer 3, a pump source 3, a gain fiber 3, and an optical isolator 3.

[0070] In the first-stage, second-stage, and third-stage fiber pre-amplification circuits, the inputs of wavelength division multiplexers 1, 2, and 3 are connected to the outputs of pump sources 1, 2, and 3, respectively. The outputs of these multiplexers are connected to the inputs of gain fibers 1, 2, and 3, respectively. The outputs of gain fibers 1, 2, and 3 are connected to the inputs of optical isolators 1, 2, and 3, respectively. The outputs of optical isolators 1, 2, and 3 are connected to the inputs of optical isolators 1, 2, and 3, respectively. The outputs of optical isolators 1, 2, and 3 are the outputs of the first-stage, second-stage, and third-stage fiber pre-amplification circuits, respectively.

[0071] The input of wavelength division multiplexer 1 in the first-stage fiber pre-amplification circuit is connected to seed source 102. Wavelength division multiplexer 1 couples the seed light with the pump light output from pump source 1 in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. Gain fiber 1 in the first-stage fiber pre-amplification circuit amplifies the gain of the coupled laser output from wavelength division multiplexer 1. Wavelength division multiplexer 2 in the second-stage fiber pre-amplification circuit combines the laser output from the first-stage fiber pre-amplification circuit with the laser output from pump source 2 in the second-stage fiber pre-amplification circuit. The pump light from the second-stage fiber pre-amplifier circuit is coupled to obtain and output the coupled laser. The gain fiber 2 in the second-stage fiber pre-amplifier circuit is used to amplify the gain of the coupled laser output from the wavelength division multiplexer 2 in the second-stage fiber pre-amplifier circuit. The wavelength division multiplexer 3 in the third-stage fiber pre-amplifier circuit is used to couple the laser output from the second-stage fiber pre-amplifier circuit with the pump light output from the pump source 3 in the third-stage fiber pre-amplifier circuit to obtain and output the coupled laser. The gain fiber 3 in the third-stage fiber pre-amplifier circuit is used to amplify the gain of the coupled laser output from the wavelength division multiplexer 3 in the third-stage fiber pre-amplifier circuit.

[0072] Erbium-ytterbium co-doped phosphate glass 106 is connected to the output of the third-stage fiber pre-amplifier circuit (i.e., the output of optical isolator 2). Erbium-ytterbium co-doped phosphate glass 106 is used to amplify the gain of the laser output from the second-stage fiber pre-amplifier circuit to obtain and output the target laser.

[0073] In detail, pump source 1 primarily provides energy to the system to achieve population inversion. Pump source 1 can be, but is not limited to, forward pumping, resulting in a higher beam quality. This application does not limit the wavelength of the pump source. The main function of wavelength division multiplexer 1 is to couple the seed light and the pump light output from pump source 1 together for subsequent laser excitation and gain. Wavelength division multiplexer 1 couples the seed source and pump light together in the same optical fiber via fiber optics, and then transmits them together to gain fiber 1. Gain fiber 1 can be, but is not limited to, erbium-doped fiber, and can be used, but is not limited to, to gain and amplify the laser output from the seed source. For example, it can amplify the seed source from 1mW to 100mW, with the specific amplification factor depending on the final requirements. Alternatively, gain fiber 1 can also be erbium-ytterbium co-doped fiber, which provides a higher gain, but may introduce more noise, potentially affecting the beam quality. Optical isolator 1 can be, but is not limited to, used to prevent the returned light from damaging the preceding optical path, such as damaging the seed source. In other words, the seed light, after being amplified by the gain fiber, can only continue to propagate forward to the subsequent fiber, and cannot be transmitted backward to the seed source. This is mainly to protect the preceding devices from damage caused by the returning light. Optical isolator 1 is connected to wavelength division multiplexer 1 via optical fiber.

[0074] Wavelength division multiplexer 2 primarily couples the amplified laser output from the first-stage fiber pre-amplifier circuit with the pump light for further laser excitation and amplification. Wavelength division multiplexer 2 couples the seed source and pump source together in the same fiber, then transmits the light to the subsequent gain fiber 2. Pump source 2 primarily provides pump energy for population inversion. Pump source 2 can, but is not limited to, forward pumping, improving the output beam quality. Gain fiber 2 can, but is not limited to, be erbium-ytterbium co-doped fiber, further amplifying the laser output power. The laser power can, but is not limited to, be amplified to several W to several hundred W, depending on the specific requirements. Optical isolator 2 primarily prevents returned light from damaging the preceding optical path. Optical isolator 2 can, but is not limited to, ensuring the laser transmission direction and preventing returned light from damaging preceding optical components. Optical isolator 2 is connected to the gain fiber via optical fiber. The light is then transmitted in spatial form to the subsequent erbium-ytterbium co-doped phosphate glass.

[0075] The wavelength division multiplexer 3 primarily couples the laser beam amplified by the second-stage fiber pre-amplifier circuit with the pump light for further laser excitation and gain. The wavelength division multiplexer 3 can, but is not limited to, using fiber optic coupling to couple the amplified laser beam and pump light together in the same fiber before transmitting them to the subsequent gain fiber 3. The pump source 3 can, but is not limited to, provide pump energy for population inversion in the system. The pump source 3 can, but is not limited to, use forward pumping. The gain fiber 3 can, but is not limited to, use erbium-ytterbium co-doped fiber, which can effectively increase the laser's output power. The optical isolator 3 can, but is not limited to, prevent returned light from damaging the preceding optical path, thus protecting the optical components. The erbium-ytterbium co-doped phosphate glass 106 primarily amplifies the laser output from the second-stage fiber pre-amplifier circuit again, resulting in a high-power, high-quality beam. Finally, the laser is output in the form of spatial light. By using a hybrid gain method combining gain fiber and gain crystal, the nonlinear effects that fiber gain can easily cause under high power and high peak power conditions can be avoided, thereby improving the energy and quality of the output laser.

[0076] Figure 8 This is a schematic diagram of a fiber laser according to an embodiment of this application. Figure 3 ,like Figure 8 As shown, the fiber laser may include, but is not limited to, a seed source 102, a first-stage fiber pre-amplification circuit, a second-stage fiber pre-amplification circuit, and an erbium-ytterbium co-doped phosphate glass 106 (i.e., the gain crystal mentioned above). The first-stage fiber pre-amplification circuit includes a wavelength division multiplexer 1, a pump source 1, a gain fiber 1, and an optical isolator 1. The second-stage fiber pre-amplification circuit includes a wavelength division multiplexer 2, a pump source 2, a gain fiber 2, and an optical isolator 2.

[0077] In the first-stage and second-stage fiber pre-amplification circuits, the inputs of wavelength division multiplexers 1 and 2 are connected to the outputs of pump sources 1 and 2, respectively, and the inputs of these two multiplexers are connected to the outputs of gain fibers 1 and 2, respectively. The outputs of wavelength division multiplexers 1 and 2 are connected to the inputs of optical isolators 1 and 2, respectively. The outputs of optical isolators 1 and 2 are the outputs of the first-stage and second-stage fiber pre-amplification circuits, respectively. Optical isolators 1 and 2 are used to isolate the coupled laser outputs from wavelength division multiplexers 1 and 2, respectively, to obtain and output the isolated laser.

[0078] The input of gain fiber 1 in the first-stage fiber pre-amplification circuit is connected to seed source 102. Gain fiber 1 in the first-stage fiber pre-amplification circuit is used to amplify the gain of the seed light output from seed source 102. Wavelength division multiplexer 1 in the first-stage fiber pre-amplification circuit is used to couple the amplified laser output from gain fiber 1 in the first-stage fiber pre-amplification circuit with the pump light output from pump source 1 in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. Gain fiber 2 in the second-stage fiber pre-amplification circuit is used to amplify the gain of the laser output from the first-stage fiber pre-amplification circuit. Wavelength division multiplexer 2 in the second-stage fiber pre-amplification circuit is used to couple the amplified laser output from gain fiber 2 in the second-stage fiber pre-amplification circuit with the pump light output from pump source 2 in the second-stage fiber pre-amplification circuit to obtain and output the coupled laser.

[0079] Erbium-ytterbium co-doped phosphate glass 106 is connected to the output of the second-stage fiber pre-amplifier circuit (i.e., the output of optical isolator 2). Gain crystal 106 is used to amplify the laser output from the second-stage fiber pre-amplifier circuit to obtain and output the target laser.

[0080] In detail, the seed source 102 can be, but is not limited to, a semiconductor laser with a wavelength of 1550 nm. The seed source 102 can be, but is not limited to, providing a seed light source in preparation for subsequent amplification. The seed source output power is 10 μW to 100 mW. To achieve pulsed laser output, an electrical pulse signal can be input to the input current and voltage of the seed source, thereby outputting an optical pulse signal. The pump source 1 mainly provides energy to the system to achieve population inversion. In this embodiment, the pump source 1 can be, but is not limited to, reverse pumping, resulting in a higher beam energy. This application embodiment does not limit the wavelength of the pump source. The main function of the wavelength division multiplexer 1 is to couple the seed light and the pump light output from the pump source 1 together for subsequent laser excitation and gain. The wavelength division multiplexer 1 couples the seed light source and the pump light together in the same optical fiber via an optical fiber, and then transmits them together to the gain fiber 1. The gain fiber 1 can be, but is not limited to, used to gain and amplify the laser output from the seed source. For example, the seed light can be amplified from 1mW to 100mW, with the specific amplification factor depending on the final requirements. The gain fiber 1 can be made of erbium-ytterbium co-doped fiber, which provides a higher gain, but may introduce more noise. The optical isolator 1 can be used, but is not limited to, to prevent the returned light from damaging the preceding optical path, such as damaging the seed source. In other words, the laser amplified by the gain fiber can only continue forward to the subsequent fiber and cannot be transmitted backward to the seed source. This protects the devices preceding the optical isolator 1 from damage by the returned light. The optical isolator 1 is connected to the wavelength division multiplexer 1 via optical fiber.

[0081] Wavelength division multiplexer 2 can be used, but is not limited to, to couple the amplified laser output from the first-stage fiber pre-amplifier circuit and the pump light together for further laser excitation and gain. Wavelength division multiplexer 2 couples the amplified laser and pump source into the same fiber via fiber optics, and then transmits them together to the subsequent gain fiber 2. Pump source 2 can be used, but is not limited to, to provide pump energy for population inversion in the system. Pump source 2 can be used, but is not limited to, reverse pumping to ensure beam quality. Gain fiber 2 can be used, but is not limited to, erbium-ytterbium co-doped fiber to increase the laser output power. Gain fiber 2 can further amplify the power of the amplified laser output from the second-stage fiber pre-amplifier circuit to several W to several hundred W, depending on the final requirements. Optical isolator 2 can be used, but is not limited to, to prevent return light from damaging the preceding optical path. Optical isolator 2 is connected to the gain fiber via optical fiber. The light is then transmitted in the form of spatial light to the erbium-ytterbium co-doped phosphate glass 106. Erbium-ytterbium co-doped phosphate glass 106 is primarily used to further amplify the gain of the preceding laser beam, resulting in a high-power, high-quality beam. The final laser beam is output as spatial light. By combining a hybrid gain method with gain fiber and gain crystal, the nonlinear effects that fiber gain can easily cause at high power and high peak power conditions can be avoided, thus improving the energy and quality of the output laser beam.

[0082] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods of the various embodiments of this application.

[0083] Optionally, specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementations, and will not be repeated here.

[0084] Obviously, those skilled in the art should understand that the modules or steps of this application described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented here, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, this application is not limited to any particular combination of hardware and software.

[0085] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A fiber laser, characterized in that, include: Seed source, used to output seed light; The N-stage fiber pre-amplifier circuit includes a gain fiber in each stage. The input of the first stage fiber pre-amplifier circuit is connected to the seed source, and the gain fiber in the first stage fiber pre-amplifier circuit is used to amplify the seed light. The input of the i-th stage fiber pre-amplifier circuit is connected to the output of the (i-1)-th stage fiber pre-amplifier circuit, and the gain fiber in the i-th stage fiber pre-amplifier circuit is used to amplify the laser output from the (i-1)-th stage fiber pre-amplifier circuit. N is a positive integer greater than or equal to 2, where 2 ≤ i ≤ N. A gain crystal is connected to the output of the Nth-stage fiber pre-amplifier circuit in the Nth-stage fiber pre-amplifier circuit. The gain crystal is used to amplify the laser output from the Nth-stage fiber pre-amplifier circuit to obtain and output the target laser. Wherein, the gain fiber is erbium-doped fiber or erbium-ytterbium co-doped fiber, and the gain crystal is erbium-ytterbium co-doped phosphate glass; The Nth-stage fiber pre-amplifier circuit is used to transmit the output laser in the form of spatial light and couple it into the gain crystal.

2. The fiber laser according to claim 1, characterized in that, Each stage of the N-stage fiber pre-amplification circuit further includes a wavelength division multiplexer (WDM) and a pump source. In each stage, the input of the WDM is connected to the output of the pump source, and the output of the WDM is connected to the input of the gain fiber. The input of the wavelength division multiplexer in the first-stage fiber pre-amplification circuit is connected to the seed source. The wavelength division multiplexer in the first-stage fiber pre-amplification circuit is used to couple the seed light and the pump light output from the pump source in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. The gain fiber in the first-stage fiber pre-amplification circuit is used to amplify the gain of the coupled laser output from the wavelength division multiplexer in the first-stage fiber pre-amplification circuit. The wavelength division multiplexer in the i-th stage fiber pre-amplification circuit is used to couple the laser output from the (i-1)-th stage fiber pre-amplification circuit with the pump light output from the pump source in the i-th stage fiber pre-amplification circuit to obtain and output the coupled laser. The gain fiber in the i-th stage fiber pre-amplification circuit is used to amplify the gain of the coupled laser output from the wavelength division multiplexer in the i-th stage fiber pre-amplification circuit.

3. The fiber laser according to claim 2, characterized in that, Each stage of the N-stage fiber pre-amplification circuit also includes an optical isolator. In each stage of the fiber pre-amplification circuit, the output of the gain fiber is connected to the input of the optical isolator, and the output of the optical isolator is the output of each stage of the fiber pre-amplification circuit. The optical isolator is used to isolate the amplified laser output from the gain fiber, thereby obtaining and outputting the isolated laser.

4. The fiber laser according to claim 2, characterized in that, The direction of the pump light output from the pump source in the first-stage fiber pre-amplification circuit is the same as the direction of the seed light output from the seed source; the direction of the pump light output from the pump source in the i-th-stage fiber pre-amplification circuit is the same as the direction of the laser output from the (i-1)-th-stage fiber pre-amplification circuit.

5. The fiber laser according to claim 1, characterized in that, Each stage of the N-stage fiber pre-amplification circuit further includes a wavelength division multiplexer (WDM) and a pump source. In each stage, the input of the WDM is connected to the output of the pump source, and the input of the WDM is also connected to the output of the gain fiber. The input of the gain fiber in the first-stage fiber pre-amplification circuit is connected to the seed source. The gain fiber in the first-stage fiber pre-amplification circuit is used to amplify the gain of the seed light output from the seed source. The wavelength division multiplexer in the first-stage fiber pre-amplification circuit is used to couple the amplified laser output from the gain fiber in the first-stage fiber pre-amplification circuit with the pump light output from the pump source in the first-stage fiber pre-amplification circuit to obtain and output the coupled laser. The gain fiber in the i-th stage fiber pre-amplification circuit is used to amplify the laser output from the (i-1)-th stage fiber pre-amplification circuit. The wavelength division multiplexer in the i-th stage fiber pre-amplification circuit is used to couple the amplified laser output from the gain fiber in the i-th stage fiber pre-amplification circuit with the pump light output from the pump source in the i-th stage fiber pre-amplification circuit to obtain and output the coupled laser.

6. The fiber laser according to claim 5, characterized in that, Each stage of the N-stage fiber pre-amplification circuit also includes an optical isolator. In each stage of the fiber pre-amplification circuit, the output of the wavelength division multiplexer is connected to the input of the optical isolator. The output of the optical isolator is the output of each stage of the fiber pre-amplification circuit. The optical isolator is used to isolate the coupled laser output from the wavelength division multiplexer, so as to obtain and output the isolated laser.

7. The fiber laser according to claim 5, characterized in that, The direction of the pump light output from the pump source in the first-stage fiber pre-amplifier circuit is opposite to the direction of the seed light output from the seed source; the direction of the pump light output from the pump source in the i-th-stage fiber pre-amplifier circuit is opposite to the direction of the laser output from the (i-1)-th-stage fiber pre-amplifier circuit.

8. The fiber laser according to any one of claims 1 to 7, characterized in that, The input current and input voltage of the seed source are electrical pulse signals, and the seed light output by the seed source is an optical pulse signal.

9. The fiber laser according to any one of claims 1 to 7, characterized in that, The gain fiber is doped with a first rare earth element, the first rare earth element corresponding to the wavelength of the seed light; and / or, the gain crystal is doped with a second rare earth element, the second rare earth element corresponding to the wavelength of the seed light.

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