A dual-band anti-return light protection semiconductor pump source and fiber laser

Abstract

The application relates to the technical field of high-power fiber lasers, and provides a double-waveband anti-backlight protection semiconductor pumping source and a fiber laser, the semiconductor pumping source comprising a semiconductor laser chip, a collimating optical element and an output coupling optical fiber, the input end face of the output coupling optical fiber or the optical end face in the interior of the pumping source being coated with a double-waveband anti-backlight film system, the double-waveband anti-backlight film system having high transmittance to pumping light and high reflectivity to signal light back light and bleaching light back light, so as to inhibit the reverse entry of the signal light and the bleaching light into the interior of the semiconductor pumping source. The fiber laser constructed based on the semiconductor pumping source comprises a pumping source, a signal seed source, a bleaching light source, a beam combiner and a gain optical fiber. The anti-backlight function is integrated in the pumping source, the double-waveband back light protection of the signal light and the bleaching light is realized without additionally increasing external isolator devices, and the application has the advantages of compact structure, low loss and high reliability.

Description

Technical Field

[0001] This invention relates to the field of high-power fiber laser technology, specifically to a semiconductor pump source and fiber laser with dual-band anti-backlight protection. Background Technology

[0002] High-power fiber lasers are widely used in industrial processing, space communication, and nuclear facility monitoring. As one of the core components of a fiber laser, the reliability of the semiconductor laser (LD) pump source directly affects the overall output performance and lifespan of the system.

[0003] In radiation-hardened fiber laser systems, the pump source faces a severe threat of backlight damage. During laser operation, signal light (e.g., 1064nm) may be back-propagated and coupled into the pump source due to link reflection. Without effective protection, this can easily cause the semiconductor chip to burn out. Secondly, to repair gain fiber color center damage caused by irradiation, bleaching light of a specific wavelength, such as 450nm blue light, can be introduced for photobleaching. However, due to the non-ideal isolation of devices such as beam combiners, the bleaching light can also be back-coupled into the pump source, causing thermal damage to the pump source output end face or chip burnout when the power is high.

[0004] In existing technologies, backlight protection for signal light typically involves depositing a bandpass filter with high reflectivity to the signal light on the output facet of the pump source. While this approach allows pump light (e.g., 976nm) to efficiently pass through and signal light (e.g., 1064nm) to reflect back, its film system design only addresses the pump and signal light, failing to address the multi-band backlighting issue caused by the introduction of bleaching light. Adding a separate spatial isolator or optical switch to the optical path to solve this problem would significantly increase the overall cost and package size of the laser system, introduce additional insertion loss, and reduce the system's electro-optical conversion efficiency. Therefore, providing a solution that can simultaneously protect the pump source from dual-band backlighting damage from both signal and bleaching light, while also being compact, low-loss, and highly reliable, is a critical technical problem urgently needing to be solved in this field. Summary of the Invention

[0005] This invention provides a semiconductor pump source and fiber laser with dual-band anti-backlight protection. The technical problem it aims to solve is how to enable the semiconductor pump source to simultaneously defend against backlight damage from signal light and bleaching light without adding additional external isolation devices, thereby improving the reliability of the radiation-resistant fiber laser system and reducing system loss.

[0006] To achieve the above objectives, the present invention provides the following technical solution: On the one hand, a semiconductor pump source with dual-band anti-backlight protection is provided, comprising: Semiconductor laser chip, used to output wavelength λp Pump light; Collimating optical elements are used to shape the pump light output from the semiconductor laser chip. The output coupling fiber is used to couple the pump light after beam shaping to the output. The output coupling fiber is provided with a dual-band anti-backlight film system on either the input end face or any optical end face inside the semiconductor pump source; the dual-band anti-backlight film system is effective against the pump light wavelength λ. p It has high transmittance and high reflectivity for both signal light wavelength and bleaching light wavelength, so as to suppress the reverse entry of signal light and bleaching light into the semiconductor pump source. The bleaching light is an auxiliary laser used to repair irradiation damage to the gain fiber, and the wavelength of the bleaching light is λ. b With the pump light wavelength λ p Signal light wavelength λ s They are all different.

[0007] Furthermore, the dual-band anti-reflection film system of the present invention is a multilayer interference dielectric film, which is composed of alternating layers of high refractive index material and low refractive index material.

[0008] Furthermore, the high refractive index material layer is selected from one or more combinations of Ta2O5, TiO2, HfO2, and Nb2O5; the low refractive index material layer is selected from one or more combinations of SiO2, MgF2, and Al2O3.

[0009] Furthermore, the dual-band anti-backlight film system employs an irregular film layer thickness design, ensuring that it operates within the pump light wavelength λ. p A high transmittance passband is formed at this location, and at the signal light wavelength λ s and bleaching light wavelength λ b High reflectivity bands are formed at each location.

[0010] Furthermore, the dual-band anti-backlighting film system adopts a graded refractive index design and / or a wide-angle film system design, wherein: The wide-angle film system design includes: during the film system design process, using multiple incident angles within the range of 0° to 15° as target incident angles, and using the signal light wavelength λ at the multiple incident angles as the target incident angles. s and bleaching light wavelength λ b The reflectivity at each location reaches a preset threshold as the optimization target; by increasing the wavelength λ of the signal light... s High reflectivity band and bleaching light wavelength λ b The bandwidth of the high reflection band is adjusted, and the optical thickness of the matching layer, spacer layer or phase adjustment layer is adjusted to compensate for the wavelength shift of the high reflection band under oblique incidence conditions. The gradient refractive index design includes setting a refractive index transition layer with an intermediate refractive index between at least one set of adjacent high-refractive-index material layers and low-refractive-index material layers, or setting at least one film layer as a film layer with a continuously or stepwise changing refractive index along the film layer thickness direction, thereby reducing the influence of incident angle changes on the phase matching condition of the film system, so that the dual-band anti-backlight film system maintains the signal light wavelength λ within the incident angle range of 0° to 15°. s and bleaching light wavelength λ b Its high reflectivity.

[0011] Furthermore, the dual-band anti-backlight film system has a transmittance T≥98% for the pump light and a reflectance R≥99% for both the signal light backlight and the bleaching light backlight.

[0012] On the other hand, the present invention provides a fiber laser, comprising: At least one of the aforementioned semiconductor pump sources; Gain fiber; A signal seed source is used to output a wavelength of λ. s The signal light; At least one bleaching light source is used to output a wavelength of λ. b Bleached light is used to repair irradiation damage to the gain fiber; A beam combiner is used to couple the pump light, signal light, and bleaching light into the gain fiber. The output coupling fiber input end face or internal optical end face of the semiconductor pump source has high transmittance to the pump light and high reflectivity to the signal light return and bleaching light return, thereby preventing the signal light return and bleaching light return from entering the interior of the semiconductor pump source.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves efficient transmission of pump light and high dual-band high reflection suppression of signal light and auxiliary bleaching light by setting a dual-band anti-backlight film system on the input end face or internal optical end face of the pump source output coupling fiber. It can simultaneously suppress the backflow of signal light and bleaching light into the pump source, and avoid damage to the semiconductor laser chip caused by the backflow of signal light and bleaching light.

[0014] The dual-band anti-backlight coating system of this invention can be directly deposited on either the input end face of the output coupling fiber or any optical end face inside the semiconductor pump source, eliminating the need for additional isolators or optical switches. This reduces system insertion loss and improves overall electro-optical efficiency. Simultaneously, this invention simplifies the laser structure, replacing complex external protection optical paths and reducing the packaging difficulty and total material cost of the laser system. This invention is highly integrated and solves the problem of multi-wavelength backlight damage with a large span by using a dual-band anti-backlight film system without changing the physical size of the device.

[0015] This invention specifically addresses the critical risk of bleaching light backflow burning the pump source in radiation-resistant applications, protecting chip safety and extending system lifespan. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a semiconductor pump source with dual-band anti-backlight protection provided in one embodiment; Figure 2 This is a schematic diagram of the reflection / transmission spectrum of a dual-band anti-reflection film system provided in one embodiment; Figure 3 This is a schematic diagram of a fiber laser system structure provided in one embodiment; Figure 4 This is a schematic diagram illustrating the working principle of a traditional single-band anti-reflection film system under bleaching light reflection conditions; Figure 5 This is a schematic diagram illustrating the working principle of the dual-band anti-reflection film system of the present invention under the condition of bleaching light reflection; Figure 6 is a schematic diagram of the layered structure of a dual-band anti-backlight film system provided in one embodiment.

[0018] Explanation of reference numerals in the attached figures: 101. Semiconductor laser chip; 102. Fast-axis collimating lens; 103. Slow-axis collimating lens; 104. Output coupling optical fiber; 105. Ceramic ferrule; 106. Input end face; 107. Dual-band anti-reflection film system; 201a, First semiconductor pump source; 201b, Second semiconductor pump source; 201c, Third semiconductor pump source; 202. Signal seed source; 203. Bleaching light source; 204. Bundle combiner; 205. Gain fiber; 206. Power meter; 207. Controller.

[0019] 301. Output coupling fiber input end face or internal optical end face; 302, bottom layer; 303. Bleached high reflectivity membrane stack; 304. Matching layer, spacer layer, or phase adjustment layer; 305. Signal light highly reflective membrane stack; 306, SiO2 protective layer. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described through specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Reference Figure 1 One embodiment provides a semiconductor pump source with dual-band anti-backlight protection, comprising: Semiconductor laser chip 101 is used to output a wavelength of λ. p Pump light; Collimating optical elements are used to shape the pump light output from the semiconductor laser chip 101. The output coupling fiber 104 is used to couple the pump light after beam shaping to the output. The output coupling fiber 104 has a dual-band anti-backlight film system 107 disposed on either the input end face or any optical end face inside the semiconductor pump source; the dual-band anti-backlight film system 107 is effective against the pump light wavelength λ. p It has high transmittance and high reflectivity for both signal light wavelength and bleaching light wavelength, so as to suppress the reverse entry of signal light and bleaching light into the semiconductor pump source. The bleaching light is an auxiliary laser used to repair irradiation damage to the gain fiber, and the wavelength of the bleaching light is λ. b With the pump light wavelength λ p Signal light wavelength λ s They are all different.

[0022] Reference Figure 1In this embodiment, the collimating optical element includes a fast-axis collimating lens 102 and a slow-axis collimating lens 103. The semiconductor pump source provided in this embodiment first outputs high-power pump light from the semiconductor laser chip 101. This pump light then enters the collimating optical element composed of the fast-axis collimating lens 102 and the slow-axis collimating lens 103 for beam shaping, thereby converting the laser beam with a large divergence angle into a parallel beam. The pump light, after beam shaping by the collimating optical element, is incident on the input end face of the output coupling fiber 104. The input end face of the output coupling fiber 104 is provided with a dual-band anti-backlight film system 107, which has high transmittance to the pump light. The pump light is ultimately coupled into the output coupling fiber 104 for output.

[0023] Reference Figure 1 In this embodiment, the output coupling fiber 104 is fixed in the ceramic ferrule 105, and the dual-band anti-backlight film system 107 is disposed on the input end face of the output coupling fiber 104. The dual-band anti-backlight film system 107 can be a multilayer interference dielectric film, composed of alternating layers of high-refractive-index material and low-refractive-index material. When the semiconductor pump source is working normally, the pump light can pass through the input end face of the output coupling fiber 104 and couple into the output coupling fiber 104. When the semiconductor pump source is applied to a fiber laser, when the fiber laser system generates backlight, whether it is backlight from the signal light or backlight from the photobleaching repair process, it will be reflected back by the dual-band anti-backlight film system when it comes into contact with the input end face, thereby suppressing harmful backlight from entering the semiconductor laser chip area. Preferably, the transmittance T of the dual-band anti-backlight film system for the pump light is ≥98%, and the reflectivity R for both the signal light backlight and the bleaching light backlight is ≥99%.

[0024] In other embodiments, the dual-band anti-backlight film system may also be disposed on other optical end faces inside the semiconductor pump source, and the present invention does not limit this.

[0025] Furthermore, the pump light wavelength λ p The wavelength of the signal light is in the range of 915nm to 980nm; s The wavelength of the bleaching light is in the range of 1030 nm to 1090 nm; b Located within the visible light band. Preferably, the pump light wavelength λ p The wavelength of the signal light is 976nm. s The wavelength λ of the bleaching light is 1064 nm. b It is 450nm.

[0026] Reference Figure 2The diagram shows the reflection / transmission spectrum of the dual-band anti-backlighting film system. This system is designed to have high transmittance at the 976nm pump wavelength to reduce pump energy loss. Simultaneously, utilizing the principle of thin-film interference, the system forms high-reflection bands at 450nm and 1064nm to suppress backlighting from bleaching light and signal light. The 976nm, 450nm, and 1064nm values ​​mentioned above are merely preferred parameters for this embodiment and do not constitute a limitation on the scope of protection of this invention.

[0027] In terms of material selection, the dual-band anti-backlight film system is a multilayer interference dielectric film, which is composed of alternating layers of high-refractive-index material and low-refractive-index material. In the dual-band anti-backlight film system 107, the high-refractive-index material layer is selected from one or more combinations of Ta2O5, TiO2, HfO2, and Nb2O5, and the low-refractive-index material layer is selected from one or more combinations of SiO2, MgF2, and Al2O3.

[0028] like Figure 2 The dual-band anti-reflection film system shown can use tantalum pentoxide (Ta2O5) as a high refractive index material and silicon dioxide (SiO2) as a low refractive index material, or it can use other combinations of high and low refractive index materials.

[0029] The dual-band anti-backlighting film system 107 includes a side near the input end face of the output coupling fiber or the internal optical end face of the semiconductor pump source, and a side away from the input end face of the output coupling fiber or the internal optical end face of the semiconductor pump source. A SiO2 protective layer with a thickness ranging from 100 nm to 500 nm is disposed on the side of the dual-band anti-backlighting film system 107 away from the input end face of the output coupling fiber or the internal optical end face of the semiconductor pump source. This SiO2 protective layer is located on the side of the dual-band anti-backlighting film system away from the input end face of the output coupling fiber or the internal optical end face of the semiconductor pump source, and is used to improve the mechanical strength, pollution resistance, and environmental stability of the film system.

[0030] Reference Figure 6 In one embodiment, the dual-band anti-backlight film system 107 is disposed on the input end face or internal optical end face 301 of the output coupling fiber. The input end face or internal optical end face 301 of the output coupling fiber can be the input end face 106 of the output coupling fiber 104, or other optical end faces within the semiconductor pump source. The dual-band anti-backlight film system 107 includes a bottom layer 302 near the input end face or internal optical end face 301, used for applying light at the bleaching wavelength λ. b A bleached light hyperreflector film stack 303 forms a high-reflection band and is used to adjust the pump light wavelength λ. pMatching layer, spacer layer, or phase adjustment layer 304 for transmission characteristics, used at signal light wavelength λ s The system comprises a high-reflectivity signal light high-reflectivity film stack 305 forming a high-reflectivity band, and a SiO2 protective layer 306 disposed on the side away from the input end face or internal optical end face 301 of the output coupling fiber. The SiO2 protective layer 306 is located on the outermost side of the dual-band anti-backlighting film system 107, used to improve the mechanical strength, pollution resistance, and environmental stability of the film system, with a thickness ranging from 100 nm to 500 nm. The dual-band anti-backlighting film system can employ an irregular film layer thickness design. This irregular film layer thickness design means that the dual-band anti-backlighting film system does not design all high-refractive-index material layers and low-refractive-index material layers as regular quarter-wavelength films with the same center wavelength, but rather uses the pump light wavelength λ... p Signal light wavelength λ s and bleaching light wavelength λ b With a common target design wavelength, the optical thickness of each film layer is designed differently. Specifically, the pump light wavelength λ is used as the basis for the design. p Signal light wavelength λ s and bleaching light wavelength λ b As the target design wavelength, it is set to be used for the signal light wavelength λ s The first high-reflectivity film stack forms a high-reflectivity band at the location, used for bleaching light wavelength λ. b A second high-reflectivity sublayer forming a high-reflection band, and a matching layer, spacer layer, or phase-adjusting layer disposed between or adjacent to the first and / or second high-reflectivity sublayers. The first high-reflectivity sublayer may be composed of layers adapted to the signal light wavelength λ. s The design alternates between high-refractive-index and low-refractive-index material layers, causing the signal light to return at λ. s Constructive reflection occurs nearby; the second highly reflective sub-film stack can be designed for bleaching light wavelength λ. b The design alternates between high-refractive-index and low-refractive-index material layers, causing the bleaching light to reflect back at λ. b Constructive reflection occurs nearby.

[0031] In this system, at least a portion of the films in the first and second high-reflectivity sublayers have optical thicknesses different from the regular quarter-wavelength optical thicknesses at the same center wavelength. Specifically, by providing one or more matching layers, spacer layers, or phase-adjusting layers between the first and second high-reflectivity sublayers, near the substrate, or near the outer surface, and adjusting their optical thicknesses, the dual-band anti-backlighting film system is made to operate at pump light wavelength λ. p The phase-constructive transmission condition is satisfied at the pump light wavelength λ, thus the dual-band anti-backlight film system achieves this. p A high transmittance passband is formed at the wavelength λ; while at the signal light wavelength λ sand bleaching light wavelength λ b The constructive reflection condition is satisfied at this point, thus ensuring that the signal light wavelength λ... s and bleaching light wavelength λ b High-reflection bands are formed at various locations. The physical thickness d of each film layer can be determined according to d=δ / n, where δ is the optical thickness of the film layer and n is the refractive index of the film layer material at the corresponding wavelength. The optical thickness δ can be selected within the range of one-quarter wavelength optical thickness, half wavelength optical thickness, and their deviations from the target wavelength, and the film system at λ is evaluated using the transfer matrix method. p , λ s and λ b The transmittance and reflectance at the location are calculated and optimized.

[0032] In a preferred embodiment, the pump light wavelength λ p The wavelength of the signal light is 976nm. s The wavelength λ of the bleaching light is 1064 nm. b The wavelength is 450nm. Through the aforementioned irregular film thickness design, the dual-band anti-backlight film system forms a transmission peak at 976nm, allowing efficient transmission of pump light; simultaneously, high-reflection bands are formed at 1064nm and 450nm, respectively, to reflect the signal light backlight and the bleaching light backlight. Preferably, the dual-band anti-backlight film system has a pump light wavelength λ... p The transmittance at a point T ≥ 98% is at the signal light wavelength λ. s and bleaching light wavelength λ b The reflectance at each location is R≥99%.

[0033] Furthermore, to ensure that the dual-band anti-backlighting film system 107 maintains high reflectivity for both signal light backlight and bleaching light backlight under different incident angles, the dual-band anti-backlighting film system 107 can employ a graded refractive index design and / or a wide-angle film system design. Since the equivalent optical thickness of the multilayer interference dielectric film changes under oblique incidence conditions, causing the center wavelength of the high-reflection band to shift relative to normal incidence conditions, this embodiment uses multiple incident angles within the 0° to 15° incident angle range as target incident angles during the film system design process. For example, 0°, 5°, 10°, and 15° are used as target incident angles, and the reflectivity of the dual-band anti-backlighting film system 107 for the signal light wavelength λs and bleaching light wavelength λs under these incident angles is calculated respectively. b The reflectivity, with the signal light wavelength λ at the multiple incident angles. s and bleaching light wavelength λ b The reflectivity at each location reaches a preset threshold as the optimization target; by increasing the wavelength λ of the signal light... s High reflectivity band and bleaching light wavelength λ bThe bandwidth of the high-reflection band is adjusted, and the optical thickness of the matching layer, spacer layer, or phase adjustment layer is adjusted to compensate for the wavelength shift of the high-reflection band under oblique incidence conditions.

[0034] Specifically, the reflection spectrum of the dual-band anti-backlight film system 107 at different incident angles can be calculated using the transfer matrix method, with the signal light wavelength λ in the incident angle range of 0° to 15°. s and bleaching light wavelength λ b The reflectivity at each location is not less than a preset threshold as the optimization target. The preset threshold can be 99%, or it can be set to other values ​​according to actual anti-reflection requirements. During the optimization process, the number of film layers in the signal light high reflectivity film stack 305 and the bleached light high reflectivity film stack 303 is increased, the optical thickness of the high refractive index material layer and the low refractive index material layer is adjusted, and the optical thickness of the matching layer, spacer layer, or phase adjustment layer 304 is adjusted to ensure that the signal light wavelength λ is not less than a preset threshold. s and bleaching light wavelength λ b These are located within the effective bandwidth of their respective high-reflectivity zones. Therefore, even if the incident angle changes from 0° to 15°, causing a certain wavelength shift in the high-reflectivity zone, the signal light wavelength λ remains constant. s and bleaching light wavelength λ b It remains within the corresponding high-reflectivity zone, thus maintaining high-reflectivity characteristics.

[0035] In one embodiment, the gradient refractive index design can be achieved by setting a refractive index transition layer with an intermediate refractive index between at least one set of adjacent high-refractive-index material layers and low-refractive-index material layers, or by setting at least one film layer with a refractive index that changes continuously or stepwise along the film thickness direction. This reduces the influence of incident angle changes on the phase matching conditions of the film system, ensuring that the dual-band anti-backlight film system maintains the signal light wavelength λ within the incident angle range of 0° to 15°. s and bleaching light wavelength λ b The high reflectivity characteristics. Through the above-mentioned refractive index transition layer or graded refractive index film, the phase abrupt change at the interface of adjacent film layers can be reduced, and the phase matching conditions under different incident angles can be improved, thereby improving the spectral stability of the dual-band anti-reflection film system 107 in the incident angle range of 0° to 15°.

[0036] In a preferred embodiment, the pump light wavelength λ p The wavelength of the signal light is 976nm. s The wavelength λ of the bleaching light is 1064 nm. b The wavelength is 450nm. Through the above-mentioned wide-angle film system design and / or gradient refractive index design, the dual-band anti-backlight film system 107 maintains high reflectivity for both 1064nm signal light backlight and 450nm bleaching light backlight in the incident angle range of 0° to 15°, while maintaining high transmittance at the 976nm pump light wavelength.

[0037] Understandable. Figure 2 The schematic curves of the reflection / transmission spectra of the dual-band anti-reflection film system shown are used to illustrate the spectral design goals of the dual-band anti-reflection film system at different wavelengths, rather than to limit the specific experimental test results.

[0038] Reference Figure 3 This embodiment provides a fiber laser including the aforementioned pump sources, comprising a signal seed source 202, multiple semiconductor pump sources, and a bleaching light source 203. The figure shows three semiconductor pump sources: a first semiconductor pump source 201a, a second semiconductor pump source 201b, and a third semiconductor pump source 201c. These semiconductor pump sources are those provided in any of the above embodiments. In practical applications, the number of semiconductor pump sources in a fiber laser is not limited; the required number of semiconductor pump sources is determined as needed.

[0039] A signal seed source 202, a first semiconductor pump source 201a, a second semiconductor pump source 201b, a third semiconductor pump source 201c, and a bleaching light source 203 are connected to a combiner 204. The combiner 204 is connected to a gain fiber 205. The signal light emitted from the signal seed source 202, the pump light emitted from each semiconductor pump source, and the bleaching light emitted from the bleaching light source are all coupled into the gain fiber 205 through the combiner 204. Finally, the high-power laser output from the gain fiber 204 is output via a power meter 206.

[0040] The aforementioned fiber laser is controlled by a controller 207, with the power meter 206 and the bleaching light source 203 connected to the controller 207. When the fiber laser is operating in an irradiated environment, the controller 207 monitors the power status of the power meter 206 and activates the bleaching light source 203 when necessary. The bleaching light source 203 outputs 450nm bleaching light, which enters the gain fiber for optical bleaching repair. During this process, when the 450nm bleaching light back transmitted to the pump branch contacts the input end face of the output coupling fiber of each semiconductor pump source (first semiconductor pump source 201a, second semiconductor pump source 201b, and third semiconductor pump source 201c), it is blocked by its built-in dual-band anti-backlight film system. Similarly, the backlight of the back-transmitted signal light can also be reflected by the dual-band anti-backlight film system of each semiconductor pump source, thereby reducing the risk of backlight entering the interior of each semiconductor pump source.

[0041] Furthermore, each semiconductor pump source and signal seed source can also be connected to the controller 207, and under the control of the controller 207, the working status and working parameters of each semiconductor pump source and signal seed source can be controlled.

[0042] Therefore, the fiber laser described in this embodiment can achieve protection against dual-band backlighting of signal light and bleaching light without the need for additional external isolation devices.

[0043] Reference Figure 4 and Figure 5 , Figure 4 This is a schematic diagram illustrating the working principle of a traditional single-band anti-reflection film system under bleaching light reflection conditions; Figure 5 This is a schematic diagram illustrating the working principle of the dual-band anti-reflection film system of the present invention under bleaching light reflection conditions. Based on Figure 4 and Figure 5 This paper compares and explains the working principles of a traditional single-band anti-backlight film system and the dual-band anti-backlight film system of this invention in the case of bleached light backlight, illustrating the differences between the two systems in this scenario. The traditional single-band anti-backlight film system is primarily designed for high reflectivity in the signal light band, thus providing some protection against signal light backlight. However, its ability to suppress backlight in the bleached light band is limited. When the bleached light travels in the reverse direction along the optical path to the pump source end face, some of it may still enter the pump source, increasing the risk of pump source damage. In contrast, the dual-band anti-backlight film system of this invention is designed for both the signal light and bleached light bands. Therefore, it effectively reflects both backlight and bleached light backlight when they reach the pump source end face, reducing the possibility of backlight entering the pump source. Therefore, compared with traditional single-band anti-backlight film systems, the present invention can simultaneously take into account pump light transmission and dual-band backlight suppression of signal light and bleaching light.

[0044] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0045] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A semiconductor pump source with dual-band anti-backlight protection, characterized in that, include: Semiconductor laser chip, used to output wavelength λ p Pump light; Collimating optical elements are used to shape the pump light output from the semiconductor laser chip. The output coupling fiber is used to couple the pump light after beam shaping to the output. The output coupling fiber is provided with a dual-band anti-backlight film system on either the input end face or any optical end face inside the semiconductor pump source; the dual-band anti-backlight film system is effective against the pump light wavelength λ. p It has high transmittance and high reflectivity for both signal light wavelength and bleaching light wavelength, so as to suppress the reverse entry of signal light and bleaching light into the semiconductor pump source. The bleaching light is an auxiliary laser used to repair irradiation damage to the gain fiber, and the wavelength of the bleaching light is λ. b With the pump light wavelength λ p Signal light wavelength λ s They are all different.

2. The semiconductor pump source with dual-band anti-backlight protection according to claim 1, characterized in that, The dual-band anti-reflection film system is a multilayer interference dielectric film, which is composed of alternating layers of high refractive index material and low refractive index material.

3. The semiconductor pump source with dual-band anti-backlight protection according to claim 2, characterized in that, The high refractive index material layer is selected from one or more combinations of Ta2O5, TiO2, HfO2, and Nb2O5; the low refractive index material layer is selected from one or more combinations of SiO2, MgF2, and Al2O3.

4. The semiconductor pump source with dual-band anti-backlight protection according to claim 1, 2, or 3, characterized in that, The dual-band anti-backlight film system includes a bottom layer near the input end face or internal optical end face of the output coupling fiber, used for bleaching light wavelength λ. b A bleached light hyperreflector film stack forming a high-reflection band is used to adjust the pump light wavelength λ. p Matching layers, spacers, or phase-adjusting layers for transmission characteristics, used at signal light wavelength λ s The signal light high reflectivity film stack forms a high reflectivity band, and a SiO2 protective layer is disposed on the side away from the input end face or internal optical end face of the output coupling fiber. The SiO2 protective layer is located on the outermost side of the dual-band anti-backlight film system, and its thickness ranges from 100nm to 500nm.

5. The semiconductor pump source with dual-band anti-backlight protection according to claim 4, characterized in that, The dual-band anti-backlight film system employs an irregular film layer thickness design, which includes: using the pump light wavelength λ p Signal light wavelength λ s and bleaching light wavelength λ b As the target design wavelength, it is set to be used at the signal light wavelength λ s The first high-reflectivity film stack forms a high-reflectivity band at the location, used for bleaching light wavelength λ. b A second high-reflectivity sublayer forming a high-reflection band, and a matching layer, spacer layer, or phase adjustment layer disposed between or adjacent to the first and / or second high-reflectivity sublayers, wherein the first high-reflectivity sublayer may be configured to target the signal light wavelength λ. s The design alternates between high-refractive-index and low-refractive-index material layers, causing the signal light to return at λ. s Constructive reflection occurs nearby; the second highly reflective sub-film stack can be designed for bleaching light wavelength λ. b The design alternates between high-refractive-index and low-refractive-index material layers, causing the bleaching light to reflect back at λ. b Constructive reflection occurs nearby. By setting one or more matching layers, spacer layers, or phase adjustment layers between the first and second high-reflectivity film stacks, near the substrate, or near the outer surface, and adjusting their optical thickness, the dual-band anti-backlight film system is made to operate at pump light wavelength λ. p The phase-constructive transmission condition is satisfied at the pump light wavelength λ, thus the dual-band anti-backlight film system achieves this. p A high transmittance passband is formed at the wavelength λ; while at the signal light wavelength λ s and bleaching light wavelength λ b The constructive reflection condition is satisfied at this point, thus ensuring that the signal light wavelength λ... s and bleaching light wavelength λ b High reflectivity bands are formed at each location.

6. The semiconductor pump source with dual-band anti-backlight protection according to claim 4, characterized in that, The dual-band anti-reflection film system adopts a gradient refractive index design and / or a wide-angle film system design. The wide-angle film system design includes: during the film system design process, using multiple incident angles within the range of 0° to 15° as target incident angles, and using the signal light wavelength λ at the multiple incident angles as the target incident angles. s and bleaching light wavelength λ b The reflectivity at each location reaches a preset threshold as the optimization target; by increasing the wavelength λ of the signal light... s High reflectivity band and bleaching light wavelength λ b The bandwidth of the high reflection band is adjusted, and the optical thickness of the matching layer, spacer layer or phase adjustment layer is adjusted to compensate for the wavelength shift of the high reflection band under oblique incidence conditions. The gradient refractive index design includes setting a refractive index transition layer with an intermediate refractive index between at least one set of adjacent high-refractive-index material layers and low-refractive-index material layers, or setting at least one film layer as a film layer with a continuously or stepwise changing refractive index along the film layer thickness direction, thereby reducing the influence of incident angle changes on the phase matching condition of the film system, so that the dual-band anti-backlight film system maintains the signal light wavelength λ within the incident angle range of 0° to 15°. s and bleaching light wavelength λ b Its high reflectivity.

7. The semiconductor pump source with dual-band anti-backlight protection according to claim 1, 2, 3, 5, or 6, characterized in that, The pump light wavelength λ p The wavelength of the signal light is in the range of 915nm to 980nm; s The wavelength of the bleaching light is in the range of 1030 nm to 1090 nm; b Located in the visible light band.

8. The semiconductor pump source with dual-band anti-backlight protection according to claim 7, characterized in that, The dual-band anti-backlight film system has a transmittance T≥98% for the pump light and a reflectance R≥99% for both the signal light backlight and the bleaching light backlight.

9. A fiber laser, characterized in that, include: At least one semiconductor pump source as described in claim 1, 2, 3, 5, 6, or 8; Gain fiber; A signal seed source is used to output a wavelength of λ. s Signal light; At least one bleaching light source is used to output a wavelength of λ. b Bleached light is used to repair irradiation damage to the gain fiber; A combiner is used to couple the pump light, signal light, and bleaching light into the gain fiber. The output coupling fiber input end face or internal optical end face of the semiconductor pump source has high transmittance to the pump light and high reflectivity to the signal light return and bleaching light return, thereby preventing the signal light return and bleaching light return from entering the interior of the semiconductor pump source.

10. The fiber laser according to claim 9, characterized in that, The system includes a controller that monitors the degree of irradiation damage to the gain fiber and activates the bleaching light source when the output power of the fiber laser drops to a preset threshold.

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