A 980nm fiber laser based on common pumping of an oscillator and an amplifier

Abstract

This invention provides a 980nm fiber laser based on co-pumping by an oscillator and an amplifier, comprising a pump source, an oscillator, a filter element, and a second ytterbium-doped double-clad fiber. The oscillator includes a high-reflectivity fiber grating, a first ytterbium-doped double-clad fiber, and a low-reflectivity fiber grating. The high-reflectivity fiber grating and the low-reflectivity fiber grating together form a resonant cavity. The first ytterbium-doped double-clad fiber, located within the resonant cavity, receives the pump light and generates 980nm signal light through stimulated emission. By designing an optical path structure for co-pumping by the oscillator and amplifier, and utilizing the filter element to filter out 1030nm light while allowing residual pump light to enter the subsequent amplification stage, the unabsorbed residual pump energy in the oscillator is reused. This significantly simplifies the system size and reduces costs while solving the core problems of severe pump energy waste and low optical-to-optical conversion efficiency in existing technologies.

Description

Technical Field

[0001] This invention relates to the technical field of fiber lasers, and particularly to a 980nm fiber laser based on co-pumping of an oscillator and an amplifier. Background Technology

[0002] 980nm fiber lasers have significant applications in pumping erbium-doped / ytterbium-doped fiber amplifiers, underwater communication, and frequency doubling for generating blue-green light. Currently, generating 980nm lasers based on ytterbium-doped fibers mainly faces challenges related to reabsorption loss in three-level systems and competition for spontaneous emission in four-level (1030nm band) amplification. The main technical methods for achieving 980nm laser output based on ytterbium-doped fibers can be categorized as follows: The first category is filtering and suppression methods based on special fiber waveguide structures, such as photonic bandgap fiber and W-type refractive fiber. This type of gain fiber exhibits strong loss in the 1030nm band but maintains a low-loss mode in the 980nm band, thereby suppressing the start-up of the four-level system. The advantage of this type of 980nm fiber laser is its ability to effectively suppress 1030nm ASE (all-mode optics) and achieve high-power, high-beam-quality single-mode laser output in the 980nm band. However, due to the complex fabrication process and high production cost of this fiber, coupled with the large splicing loss between this special fiber and conventional passive fiber devices, it is difficult to design an all-fiber system.

[0003] The second category is the oscillator method based on high-pump absorption optical fiber, and the main methods are: Photonic crystal fiber itself has an ultra-high core-to-packaging ratio. Thanks to the excellent single-mode output characteristics and large mode field area of ​​photonic crystal fiber, the output power and beam quality of 980nm fiber lasers are significantly improved. However, it is precisely because of its special structure that it requires the use of spatial light for pump coupling into the fiber, which results in a large and unstable laser system. It also places high demands on the precise adjustment of the optical path, making it unsuitable for the engineering needs of the system.

[0004] Secondly, special treatment is applied to the gain fiber. By altering the refractive index of the gain fiber, the coupling efficiency of the pump light is affected, thus achieving 980nm ytterbium-doped fiber laser output. Examples include tapered fibers, jacketed air-clad fibers, or saddle-shaped fibers. These fibers require fiber gratings to construct the resonant cavity, resulting in a relatively compact structure. However, in 980nm ytterbium-doped fiber lasers, to suppress parasitic oscillations in the 1030nm band, a shorter gain fiber is typically needed to maintain a high inversion population distribution. However, the shorter fiber length leads to insufficient pump light absorption and lower optical-to-optical conversion efficiency. Increasing the fiber length to improve absorption, on the other hand, easily triggers ASE bursts in the 1030nm band, limiting the 980nm laser output power and making it difficult to achieve stable high-power operation.

[0005] The third type is the master oscillator power amplifier (MOPA) structure based on traditional independent pumping. This structure includes a low-power seed source (oscillator) and one or more power amplification stages. Its advantage is that it can achieve high power output while maintaining good beam quality. However, in the traditional 980nm MOPA structure, the oscillator and amplifier are usually pumped separately by independent pump sources. This approach has the following disadvantages: the system is complex and costly, requiring multiple independent pump drive circuits and temperature control systems, which increases the system size and cost; secondly, the utilization rate of pump light is not high. In single-stage pumping, in order to prevent ASE, the gain fiber is generally short, and there is often a large amount of residual pump light that is not absorbed. This residual energy is usually blocked by isolators (ISO) or discharged by cladding optical strippers (CPS), failing to achieve energy sharing or recycling between stages, which limits the electro-optical efficiency and compactness of the overall system. Summary of the Invention

[0006] The purpose of this invention is to provide a 980nm fiber laser with a simplified structure and energy saving based on the co-pumping of an oscillator and an amplifier.

[0007] This invention provides a 980nm fiber laser based on co-pumping by an oscillator and an amplifier, comprising a pump source, an oscillator, a filter element, and a second ytterbium-doped double-clad fiber. The pump source emits pump light. The oscillator includes a high-reflectivity fiber grating, a first ytterbium-doped double-clad fiber, and a low-reflectivity fiber grating. The high-reflectivity fiber grating and the low-reflectivity fiber grating together form a resonant cavity. The first ytterbium-doped double-clad fiber, located within the resonant cavity, receives the pump light and generates 980nm signal light through stimulated emission. The filter element filters out 1030nm amplified spontaneous emission (ASE) generated in the oscillator, ensuring low-loss passage of the 980nm signal light and residual pump light. The second ytterbium-doped double-clad fiber is fused to the filter element and acts as an amplifier to receive residual pump light and generate 980nm signal light through stimulated emission for power amplification, preparing for outputting the 980nm signal light.

[0008] Optionally, the high-reflectivity fiber grating and the low-reflectivity fiber grating are Bragg gratings respectively etched on the core of a passive fiber fused to the first ytterbium-doped double-clad fiber. The high-reflectivity fiber grating has a reflectivity R>99% for 980nm signal light, and the low-reflectivity fiber grating has a reflectivity R=10%~30% for 980nm signal light (the high-reflectivity fiber grating and the low-reflectivity fiber grating have high transmittance for 915nm pump light).

[0009] Optionally, the filter element is a first chirped tilted fiber grating.

[0010] Optionally, the fiber laser further includes a cladding light stripper, which is located at the output end of the second ytterbium-doped double-clad fiber and is used to filter out the remaining pump light to output a 980nm optical signal.

[0011] Optionally, the fiber laser further includes a first beam combiner, which is disposed between the pump source and the high-reflectivity fiber grating, for coupling the pump light generated by the pump source to the high-reflectivity fiber grating.

[0012] Optionally, the fiber laser further includes a second beam combiner disposed after the second ytterbium-doped double-clad fiber. The pump source is used to inject pump light in a reverse pumping manner, and the second beam combiner is used to couple the pump light to the second ytterbium-doped double-clad fiber and output a 980nm optical signal.

[0013] Optionally, the fiber laser further includes a second chirped tilted fiber grating, which is fused to the second ytterbium-doped double-clad fiber and used for secondary filtering of 1030nm amplified spontaneous emission (ASE).

[0014] Optionally, the fiber laser further includes a third ytterbium-doped double-clad fiber, which is fused to the second chirped tilted fiber grating to receive the residual pump light to generate 980nm signal light for secondary power amplification.

[0015] The beneficial effects of this plan are as follows: To address the issues of insufficient pump absorption in existing 980nm lasers due to ASE suppression and the complexity and high cost of traditional MOPA independent pump structures, this paper proposes a new optical path structure that uses an oscillator (a combination of a high-reflectivity fiber grating, a first ytterbium-doped double-clad fiber, and a low-reflectivity fiber grating) and an amplifier (a second ytterbium-doped double-clad fiber) for joint pumping. By utilizing a filter element to filter out 1030nm light while allowing residual pump light to enter the subsequent amplification stage, the paper realizes the reuse of unabsorbed residual pump energy in the oscillator. This significantly simplifies the system size, reduces costs, and solves the core problems of severe pump energy waste and low optical-to-optical conversion efficiency in existing technologies. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the optical path architecture of the first embodiment; Figure 2 This is a schematic diagram of the optical path architecture of the second embodiment; Figure 3 This is a schematic diagram of the optical path architecture of the third embodiment; Figure 4 This is a schematic diagram of the optical path architecture of the fourth embodiment.

[0017] Explanation of reference numerals in the attached figures: 1. Pump source; 2. High-reflectivity fiber grating; 3. First ytterbium-doped double-clad fiber; 4. Low-reflectivity fiber grating; 5. First chirped tilted fiber grating; 6. Second ytterbium-doped double-clad fiber; 7. Cladding optical stripper; 91. First combiner; 92. Second combiner; 10. Second chirped tilted fiber grating; 11. Third ytterbium-doped double-clad fiber. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention; the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "joined" should be interpreted broadly, for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or they can refer to the internal communication of two components. For those skilled in the art, the specific meaning of the terms in this invention can be understood according to the specific circumstances.

[0020] First Embodiment See Figure 1This embodiment discloses a 980nm fiber laser based on joint pumping by an oscillator and an amplifier, including a pump source 1, an oscillator, a first chirped tilted fiber grating 5, a second ytterbium-doped double-clad fiber 6, and a cladding light stripper 7. The pump source 1 is used to emit pump light. The oscillator includes a high-reflectivity fiber grating 2, a first ytterbium-doped double-clad fiber 3, and a low-reflectivity fiber grating 4. The high-reflectivity fiber grating 2 and the low-reflectivity fiber grating 4 together form a resonant cavity. The first ytterbium-doped double-clad fiber 3 is located within the resonant cavity to receive the pump light. Stimulated emission generates 980nm signal light. A filter element is used to filter out the 1030nm amplified spontaneous emission (ASE) generated in the oscillator, ensuring that the 980nm signal light and residual pump light pass through with low loss. The second ytterbium-doped double-clad fiber 6 is fused to the filter element and acts as an amplifier to receive residual pump light to stimulate the generation of 980nm signal light for power amplification. The cladding stripper 7 is located at the output end of the second ytterbium-doped double-clad fiber 6 to filter out the remaining pump light to output the 980nm optical signal.

[0021] Specifically, pump source 1 provides laser light of a wavelength that can be absorbed by the first ytterbium-doped double-clad fiber 3, and the generated pump light is coupled into the high-reflectivity fiber grating 2 through a pigtail.

[0022] In this design, the high-reflectivity fiber grating 2 and the low-reflectivity fiber grating 4 are Bragg gratings respectively inscribed on the core of the passive fiber fused to the first ytterbium-doped double-clad fiber 3, with the center wavelengths of the two fiber gratings being the same. The high-reflectivity fiber grating 2 has a reflectivity R>99% for 980nm signal light and high transmittance for 915nm pump light. The low-reflectivity fiber grating 4 has a reflectivity R=10%~30% for 980nm signal light. The high-reflectivity fiber grating 2 and the low-reflectivity fiber grating 4 together form a resonant cavity, reflecting part of the 980nm signal light back into the cavity to maintain oscillation, while simultaneously outputting the generated 980nm laser light and the residual pump light not absorbed by the first ytterbium-doped double-clad fiber 3 to the subsequent stage.

[0023] Furthermore, the working principle of the chirped tilted fiber grating (CTFBG) can be understood as a "dual upgrade" of the ordinary fiber Bragg grating (FBG). It combines the "tilted" and "chirped" structures to achieve a unique optical manipulation capability: efficiently guiding and filtering out specific wavelengths of light transmitted in the fiber core, while ensuring that other wavelengths of light pass through almost unaffected. In this embodiment, the first chirped tilted fiber grating 5 has a specific tilt angle between its grating surface and the fiber axis, and its grating period varies with chirp along the axial direction. It is a band-stop filter whose core function is to filter out 1030nm ASE, preventing it from being amplified in subsequent stages; simultaneously, it ensures that the 980nm signal light and the 915nm residual pump light pass through with extremely low loss.

[0024] In this embodiment, both the first ytterbium-doped double-clad fiber 3 and the second ytterbium-doped double-clad fiber 6 are gain media used to efficiently convert pump light into powerful laser light. The ytterbium-doped double-clad fiber comprises a core, an inner cladding, and an outer cladding, clad from the inside out. The core is the central part of the fiber, typically very thin in diameter. Rare-earth ions ytterbium (Yb³+) are doped into silica material as the laser gain medium, where the signal light is amplified and ultimately output as high-quality laser light. The inner cladding receives and reflects the pump light in multiple layers; the light is repeatedly reflected within it, and each time it passes through the core, a portion of the energy is absorbed by the ytterbium-doped core. The non-circular design breaks the symmetry of the circle, preventing the pump light from forming a stable spiral path without passing through the core, thus greatly improving absorption efficiency. The outer cladding is composed of a polymer with extremely low refractive index or a high-temperature resistant coating. It firmly confines the pump light within the inner cladding, ensuring no energy leakage and protecting the fiber from external environmental influences.

[0025] The first ytterbium-doped double-clad fiber 3 serves as the gain medium for the oscillator, absorbing part of the pump energy emitted by the pump source 1 to achieve population inversion and generate stimulated emission in the 980nm band. The second ytterbium-doped double-clad fiber 6 serves as the gain medium for the amplification stage, fused after the first chirped tilted fiber grating 5. It utilizes the residual pump light leaking from the oscillator and passing through the first chirped tilted fiber grating 5 as the pump source 1 to amplify the power of the filtered pure 980nm signal light (MOPA mode), thereby significantly improving the final output laser power and optical-to-optical conversion efficiency.

[0026] MOPA is an abbreviation for Master Oscillator Power-Amplifier. It's not a specific fiber or device, but a classic laser architecture design. It consists of two stages: the master oscillator stage (MO): a low-power but extremely high-quality, spectrally excellent laser seed source. Its task is to generate a "perfect seed beam." The power amplifier stage (PA): one or more amplifier stages. Its task is to amplify the power of the seed beam while preserving its excellent characteristics as much as possible. The MOPA mode is a technical architecture that achieves high-power, high-quality laser output through a "high-quality seed source" + "multi-stage power amplifiers."

[0027] Furthermore, the cladding light stripper 7 (CPS) is a passive device that is entirely made of fiber optics. It is usually made by special etching or coating the fiber cladding with a high refractive index polymer material. It uses the physical mechanism of refractive index matching or breaking the total internal reflection condition to couple the light beam (i.e. non-core light) transmitted in the fiber cladding out of the fiber surface and convert it into heat energy dissipation or output.

[0028] The working process of this embodiment is as follows: Pump injection stage: Pump source 1 emits 915nm pump light, which passes through the high-reflectivity fiber grating 2 and enters the first ytterbium-doped double-clad fiber 3 of the gain fiber.

[0029] Oscillation generation stage: The first ytterbium-doped double-clad fiber 3 absorbs part of the pump light, forming a 980nm laser oscillation within the resonant cavity formed by the high-reflectivity fiber grating 2 and the low-reflectivity fiber grating 4. At this time, due to the short gain fiber, the beam from the low-reflectivity fiber grating 4 at the output end contains three components: 980nm signal light, unabsorbed residual pump light, and unwanted 1030nm amplified spontaneous emission (ASE).

[0030] Spectral purification stage: The aforementioned mixed beam enters the first chirped tilted fiber grating 5. This device selectively couples the 1030nm ASE out of the fiber core, while the 980nm signal light and residual pump light pass through almost without loss.

[0031] Cascaded amplification stage: The pure 980nm signal light and residual pump light enter the second ytterbium-doped double-clad fiber 6 of the gain fiber. The second ytterbium-doped double-clad fiber 6 continues to absorb the remaining pump energy, further amplifying the 980nm signal light.

[0032] Output stage: The amplified high-power, high signal-to-noise ratio 980nm laser enters the cladding light stripper 7 from the end of the second ytterbium-doped double-clad fiber 6. Then, the cladding light stripper 7 filters out the last remaining pump light, and the end of the fiber is cut at an angle to output the 980nm signal light.

[0033] Second Embodiment See Figure 2 This embodiment discloses a 980nm fiber laser based on joint pumping by an oscillator and an amplifier, including a pump source 1, a first combiner 91, an oscillator, a first chirped tilted fiber grating 5, a second ytterbium-doped double-clad fiber 6, and a cladding stripper 7. The pump source 1 is used to emit pump light. The oscillator includes a high-reflectivity fiber grating 2, a first ytterbium-doped double-clad fiber 3, and a low-reflectivity fiber grating 4. The high-reflectivity fiber grating 2 and the low-reflectivity fiber grating 4 together form a resonant cavity. The first ytterbium-doped double-clad fiber 3 is located within the resonant cavity to receive light. The pump light generates a 980nm signal light through stimulated emission. The filter element is used to filter out the 1030nm amplified spontaneous emission (ASE) generated in the oscillator, ensuring that the 980nm signal light and residual pump light pass through with low loss. The second ytterbium-doped double-clad fiber 6 is fused to the filter element and acts as an amplifier to receive the residual pump light to generate a 980nm signal light for power amplification. The cladding stripper 7 is located at the output end of the second ytterbium-doped double-clad fiber 6 and is used to filter out the remaining pump light to output the 980nm optical signal.

[0034] Compared to the first embodiment, this embodiment adds a first beam combiner 91, which is located between the pump source 1 and the high-reflectivity fiber grating 2, and is used to couple the pump light generated by the pump source 1 to the high-reflectivity fiber grating 2. At the same time, the signal fiber of the first beam combiner 91 needs to be angle-cut to avoid backlighting.

[0035] Third Embodiment See Figure 3 This embodiment discloses a 980nm fiber laser based on joint pumping by an oscillator and an amplifier, including a pump source 1, a first combiner 91, an oscillator, a first chirped tilted fiber grating 5, a second ytterbium-doped double-clad fiber 6, and a cladding stripper 7. The pump source 1 is used to emit pump light. The oscillator includes a high-reflectivity fiber grating 2, a first ytterbium-doped double-clad fiber 3, and a low-reflectivity fiber grating 4. The high-reflectivity fiber grating 2 and the low-reflectivity fiber grating 4 together form a resonant cavity. The first ytterbium-doped double-clad fiber 3 is located within the resonant cavity to receive light. The pump light generates a 980nm signal light through stimulated emission. The filter element is used to filter out the 1030nm amplified spontaneous emission (ASE) generated in the oscillator, ensuring that the 980nm signal light and residual pump light pass through with low loss. The second ytterbium-doped double-clad fiber 6 is fused to the filter element and acts as an amplifier to receive the residual pump light to generate a 980nm signal light for power amplification. The cladding stripper 7 is located at the output end of the second ytterbium-doped double-clad fiber 6 and is used to filter out the remaining pump light to output the 980nm optical signal.

[0036] Similar to the second embodiment, this embodiment adds a second beam combiner 92. The difference is that the second beam combiner 92 in this solution is located after the second ytterbium-doped double-clad fiber 6. The pump source 1 is used to inject pump light in a reverse pumping manner, and the second beam combiner 92 is used to couple the pump light to the second ytterbium-doped double-clad fiber 6 and output a 980nm optical signal.

[0037] The second combiner 92 and the pump source 1 inject pump light into the second ytterbium-doped double-clad fiber 6 of the gain fiber using a reverse pumping method. After passing through the first chirped tilted fiber grating 5 and the low-reflection fiber grating 4, the high-reflection fiber grating 2 and the low-reflection fiber grating 4 form a resonant cavity to excite 980nm signal light. The remaining pump light is filtered out by the cladding light stripper 7. The generated 980nm signal light is filtered out by 1030nm ASE by the first chirped tilted fiber grating 5 and then re-enters the second ytterbium-doped double-clad fiber 6 of the gain fiber for amplification. Finally, it is output from the output end of the second combiner 92. The bare fibers at both ends are cut at an angle.

[0038] Fourth embodiment See Figure 4This embodiment discloses a 980nm fiber laser based on joint pumping by an oscillator and an amplifier, including a pump source 1, an oscillator, a first chirped tilted fiber grating 5, a second ytterbium-doped double-clad fiber 6, a second chirped tilted fiber grating 10, a third ytterbium-doped double-clad fiber 11, and a cladding stripper 7. The pump source 1 is used to emit pump light. The oscillator includes a high-reflectivity fiber grating 2, a first ytterbium-doped double-clad fiber 3, and a low-reflectivity fiber grating 4. The high-reflectivity fiber grating 2 and the low-reflectivity fiber grating 4 together form a resonant cavity. The first ytterbium-doped double-clad fiber... 3. The resonant cavity receives pump light to generate 980nm signal light through stimulated emission. The filter element is used to filter out the 1030nm amplified spontaneous emission (ASE) generated in the oscillator, ensuring that the 980nm signal light and residual pump light pass through with low loss. The second ytterbium-doped double-clad fiber 6 is fused to the filter element and acts as an amplifier to receive residual pump light to generate 980nm signal light for power amplification. The cladding stripper 7 is located at the output end of the second ytterbium-doped double-clad fiber 6 to filter out the remaining pump light and output the 980nm optical signal.

[0039] Compared with the first embodiment, this solution adds a second chirped tilted fiber grating 10 and a third ytterbium-doped double-clad fiber 11, while the remaining structural components are the same as those in the first embodiment.

[0040] The second chirped tilted fiber grating 10 is fused to the second ytterbium-doped double-clad fiber 6 and is used for secondary filtering of 1030nm amplified spontaneous emission (ASE). The third ytterbium-doped double-clad fiber 11 is fused to the second chirped tilted fiber grating 10 and is used to receive residual pump light to generate 980nm signal light for secondary power amplification.

[0041] First, the pump light provided by pump source 1 is excited by a 980nm signal light through a resonant cavity composed of a high-reflectivity fiber grating 2 and a low-reflectivity fiber grating. The generated 980nm signal light is filtered by a filter element (first chirped tilted fiber grating 5) to remove 1030nm ASE, and then amplified for the first time by the second gain fiber, second ytterbium-doped double-clad fiber 6. After amplification, the 980nm signal light is filtered again by the second chirped tilted fiber grating 10 to remove 1030nm ASE, and then amplified by the third gain fiber, third ytterbium-doped double-clad fiber 11. Finally, the remaining pump light is filtered by the cladding stripper 7.

[0042] The second chirped tilted fiber grating 10 also filters out the 1030nm ASE, preventing it from being amplified in subsequent stages, while ensuring that the 980nm signal light and the 915nm residual pump light pass through with extremely low loss. The third ytterbium-doped double-clad fiber 11 serves as the gain fiber for the second-stage amplification. It uses the residual pump light leaking from the oscillator and passing through the second chirped tilted fiber grating 10 as pump source 1 to amplify the power of the filtered pure 980nm signal light, thereby significantly improving the final output laser power and optical-to-optical conversion efficiency.

[0043] Understandably, the use of the second chirped tilted fiber grating 10 and the third ytterbium-doped double-clad fiber 11 can further improve the optical-to-optical conversion efficiency. Depending on different scenario requirements, multiple sets of the second chirped tilted fiber grating 10 and the third ytterbium-doped double-clad fiber 11 can be added.

[0044] This invention achieves the reuse of residual pump light from the previous stage and effectively filters out 1030nm ASE by using a structure where the oscillator and amplifier are pumped together and by introducing interstage filter elements (such as CTFBG). Compared with the prior art, this solution significantly improves the optical-to-optical conversion efficiency of the whole machine while ensuring high-purity 980nm laser output and greatly reduces the number of devices, thus achieving miniaturization and low cost of the system.

[0045] The high-efficiency 980nm fiber laser proposed in this invention, with its high power and compact structure, can be widely used as the core pump source of high-power erbium-doped / ytterbium-doped fiber amplifiers, or generate blue-green laser through nonlinear frequency doubling, and applied to precision fields such as underwater laser communication, marine exploration and biomedicine.

[0046] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A 980nm fiber laser based on co-pumping of an oscillator and an amplifier, characterized in that, include: Pump source, used to emit pump light; An oscillator comprising a high-reflectivity fiber grating, a first ytterbium-doped double-clad fiber, and a low-reflectivity fiber grating, wherein the high-reflectivity fiber grating and the low-reflectivity fiber grating together constitute a resonant cavity, and the first ytterbium-doped double-clad fiber is located within the resonant cavity to receive the pump light and generate 980nm signal light through stimulated emission. The filter element is used to filter out the 1030nm amplified spontaneous emission generated in the oscillator, ensuring that the 980nm signal light and residual pump light pass through with low loss. The second ytterbium-doped double-clad fiber, fused to the filter element, serves as an amplifier to receive residual pump light to generate 980nm signal light for power amplification, in order to output 980nm signal light.

2. The 980nm fiber laser based on co-pumping of an oscillator and an amplifier according to claim 1, characterized in that, The high-reflectivity fiber grating and the low-reflectivity fiber grating are Bragg gratings respectively etched on the core of a passive optical fiber fused to the first ytterbium-doped double-clad optical fiber. The high-reflectivity fiber grating has a reflectivity R>99% for 980nm signal light, and the low-reflectivity fiber grating has a reflectivity R=10%~30% for 980nm signal light.

3. The 980nm fiber laser based on co-pumping of an oscillator and an amplifier according to claim 1, characterized in that, The filter element is a first chirped tilted fiber grating.

4. The 980nm fiber laser based on co-pumping of an oscillator and an amplifier according to claim 1, characterized in that, The fiber laser also includes a cladding light stripper, which is located at the output end of the second ytterbium-doped double-clad fiber and is used to filter out the remaining pump light to output a 980nm optical signal.

5. The 980nm fiber laser based on co-pumping of an oscillator and an amplifier according to claim 1, characterized in that, The fiber laser further includes a first beam combiner, which is disposed between the pump source and the high-reflectivity fiber grating, for coupling the pump light generated by the pump source to the high-reflectivity fiber grating.

6. The 980nm fiber laser based on co-pumping of an oscillator and an amplifier according to claim 1, characterized in that, The fiber laser further includes a second beam combiner disposed after the second ytterbium-doped double-clad fiber. The pump source is used to inject pump light in a reverse pumping manner. The second beam combiner is used to couple the pump light to the second ytterbium-doped double-clad fiber and output a 980nm optical signal.

7. The 980nm fiber laser based on co-pumping of an oscillator and an amplifier according to claim 3, characterized in that, The fiber laser also includes a second chirped tilted fiber grating, which is fused to the second ytterbium-doped double-clad fiber and is used for secondary filtering of 1030nm amplified spontaneous emission.

8. The 980nm fiber laser based on co-pumping of an oscillator and an amplifier according to claim 7, characterized in that, The fiber laser also includes a third ytterbium-doped double-clad fiber, which is fused to the second chirped tilted fiber grating to receive the residual pump light and generate 980nm signal light for secondary power amplification.

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