Laser pumping source protection device and fiber laser

Abstract

The invention discloses a laser pumping source protection device and an optical fiber laser. The laser pumping source protection device comprises a laser pumping device, a pumping source isolator, a pumping source protector, a high-reflectivity grating group, an optical fiber beam combiner, a seed source, an active optical fiber and a signal optical isolator. Wherein the pumping source isolator, the pumping source protector and the high-reflection grating group are sequentially arranged along a laser propagation path, so that medium-frequency-band reverse light is blocked by the pumping source isolator, low-frequency-band reverse light is inhibited by the pumping source protector, and high-frequency-band reverse light is reflected by the high-reflection grating group. The seed source is used for transmitting signal light, the optical fiber beam combiner is used for coupling the signal light and pump light, the active optical fiber is used for exciting doped ions and amplifying the signal light, and the signal light isolator is used for isolating the signal light in the coupled light. According to the device, the three different optical suppression elements are used for blocking or reflecting the reverse light of different wavebands to form three-level protection, so that the reliability of the laser is improved, and the service life of the laser is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber laser equipment, and in particular to a laser pump source protection device and an optical fiber laser. Background Art

[0002] In fiber lasers, the pump source (such as a semiconductor laser) is susceptible to interference from reverse-propagating light (such as signal light, ASE noise, Stokes light, etc.), resulting in wavelength detuning, efficiency degradation, and even permanent damage.

[0003] Existing protection solutions often rely on single isolators or fiber Bragg gratings (FBGs), which fail to protect against full-band reverse light. Conventional isolators are only effective for specific wavelengths (such as the pump wavelength) and lack the ability to isolate signal light or high-frequency noise. Highly reflective FBGs require sophisticated optical path design. If improperly designed, they can reflect signal light back toward the pump source, exacerbating the risk of damage. Furthermore, existing collaborative mechanisms for reverse light band-specific protection are not yet mature, leading to complex or costly systems. Summary of the Invention

[0004] The present invention provides a laser pump source protection device and an optical fiber laser, so as to improve the reliability and service life of the laser.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] A first aspect of the technical solution of the present invention provides a laser pump source protection device, comprising:

[0007] a laser pump, configured to emit pump light of a preset wavelength;

[0008] A pump source isolator is provided at the output end of the laser pump along the propagation direction of the pump light, so as to block the unabsorbed mid-frequency band reverse light;

[0009] A pump source protector is provided at the output end of the pump source isolator along the propagation direction of the pump light, so as to suppress low-frequency reverse light;

[0010] A high-reflection grating group is arranged at the output end of the pump source protector along the propagation direction of the pump light, so as to reflect high-frequency reverse light and the band that cannot be covered by the pump source isolator and the pump source protector;

[0011] an optical fiber combiner, arranged at the output end of the high-reflection grating group along the propagation direction of the pump light, for coupling the pump light and the signal light to form coupled light;

[0012] a seed source connected to an input end of the optical fiber combiner, for emitting signal light toward the optical fiber combiner;

[0013] an active optical fiber, arranged at the output end of the optical fiber combiner along the propagation direction of the coupled light, for exciting doped ions and amplifying the signal light in the coupled light;

[0014] A signal light isolator is provided at the output end of the active optical fiber along the propagation direction of the coupled light, so as to isolate the signal light in the coupled light and enable the signal light to be transmitted in one direction.

[0015] Preferably, the low-frequency band reverse light is ASE noise in a first preset band, the mid-frequency band reverse light is pump reverse light in a second preset band, and the high-frequency band reverse light is signal reverse light in a third preset band.

[0016] Preferably, the laser pump, pump source isolator, pump source protector and high-reflection grating group together form a laser pump assembly;

[0017] The laser pump source protection device includes at least two laser pump components, each of which is connected to the input end of the optical fiber combiner to provide pump light of different wavelength bands;

[0018] The pump lights of different wavelength bands can be coupled with the signal light to form different coupled lights.

[0019] Preferably, the pump source protector comprises a band-stop filter, the stopband range of which covers ±50 nm of the signal light wavelength, so as to absorb low-frequency noise or reflect the low-frequency noise to an attenuation path.

[0020] Preferably, the reflection wavelength of the high-reflection grating group corresponds to the wavelength of the signal light emitted by the seed source, and the reflectivity is greater than 99%.

[0021] Preferably, the operating wavelength of the pump source isolator corresponds to the pump light of the preset wavelength and has a preset isolation degree, so that the isolation bandwidth range of the pump source isolator is ±10 nm of the preset wavelength of the pump light.

[0022] Preferably, the high-reflection grating group reflects the high-frequency reverse light and the wavelength band that cannot be covered by the pump source isolator and the pump source protector to the active optical fiber for secondary absorption.

[0023] Preferably, the laser pump, pump source isolator, pump source protector, high-reflection grating group, fiber combiner, seed source, active optical fiber and signal optical isolator are compactly arranged through fiber fusion or spatial optical path.

[0024] Preferably, both ends of each optical fiber used for optical fiber fusion splicing are provided with a heat sink having a through-hole structure, so that the two ends of the optical fiber pass through the through-holes of the corresponding heat sink respectively;

[0025] After the ends of two adjacent optical fibers are fused together, the heat sink is used to conduct heat to the outside.

[0026] A second aspect of the technical solution of the present invention provides a fiber laser, comprising the above-mentioned laser pump source protection device.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The laser pump source protection device of the present invention sequentially arranges a pump source isolator, a pump source protector, and a high-reflectivity grating group along the laser propagation path. The pump source isolator blocks mid-frequency reverse light, the pump source protector suppresses low-frequency reverse light, and the high-reflectivity grating group reflects high-frequency reverse light. Thus, three different optical suppression elements are used to block or reflect reverse light in different wavelength bands, forming a three-level protection system, thereby improving the reliability and service life of the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic structural diagram of a laser pump source protection device provided in the first embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of optical fiber fusion splicing in the first embodiment of the present invention;

[0031] Figure 3 This is a structural diagram of a laser pump source protection device provided by the second embodiment of the present invention.

[0032] In the accompanying drawings, each reference numeral represents:

[0033] 1. Laser pump; 2. Pump source isolator; 3. Pump source protector; 4. High-reflection grating group; 5. Fiber combiner; 6. Seed source; 7. Active optical fiber; 8. Signal optical isolator; 9. Heat sink; 10. Laser pump assembly. DETAILED DESCRIPTION

[0034] In order to make the purposes, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0035] The core idea of ​​the embodiments of the present invention is to set different optical devices along the laser propagation path, so as to suppress the damage of different reverse light to the pump source in different bands according to the characteristics of different optical devices, thereby improving the reliability and life of the laser.

[0036] First embodiment:

[0037] like Figure 1 As shown, a laser pump source protection device according to a first embodiment of the present invention includes a laser pump 1, a pump source isolator 2, a pump source protector 3, a high-reflection grating group 4, a fiber combiner 5, a seed source 6, an active fiber 7, and a signal light isolator 8. The laser pump 1, pump source isolator 2, pump source protector 3, and high-reflection grating group 4 together form a laser pump assembly 10, which is used to suppress damage to the pump source caused by different reverse light bands. The seed source 6 is used to emit signal light, the fiber combiner 5 is used to couple the signal light with the pump light, the active fiber 7 is used to excite doped ions and amplify the signal light in the coupled light, and the signal light isolator 8 is used to isolate the signal light from the coupled light, ensuring unidirectional transmission of the signal light.

[0038] Specifically, in this embodiment, the laser pump source 1 is used to emit pump light of a preset wavelength. The preset wavelength includes at least typical wavelengths of 793 nm, 808 nm, 915 nm, 940 nm, 976 nm, etc. Preferably, the preset wavelength of the laser pump source 1 is set to 976 nm.

[0039] A pump source isolator 2 is positioned at the output of the laser pump 1, along the propagation direction of the pump light, to block unabsorbed mid-frequency reverse light. Specifically, the pump source isolator 2 operates at a wavelength of 976 nm, offers an isolation rating of >35 dB, and covers an isolation bandwidth of 976 ± 10 nm. Accordingly, the mid-frequency reverse light blocked by the pump source isolator 2 is pump reverse light within the 976 ± 10 nm wavelength range (i.e., the second predetermined wavelength range).

[0040] The pump source protector 3 is positioned at the output of the pump source isolator 2 along the propagation direction of the pump light to suppress low-frequency return light. Specifically, the pump source protector 3 includes a band-stop filter whose stopband range covers ±50 nm of the signal light wavelength. For example, if the signal light wavelength is 1070 nm, the stopband is 1020-1120 nm. It is understood that this stopband range represents the return light range that can be blocked by existing pump source protectors on the market, including signal light. The laser pump source generates light within this range by exciting the gain medium, and the primary stray light that damages the laser pump source lies within this range.

[0041] Thus, the pump source protector 3 only allows light from the laser pump source 1 to pass in the forward direction, while blocking all light from the laser pump source from passing in the reverse direction. This absorbs low-frequency noise or reflects it into an attenuation path. Furthermore, in this embodiment, the low-frequency reverse light is ASE noise within a first predetermined wavelength band. It should be understood that ASE (Amplified Spontaneous Emission) noise, or ASE light, is relative to the laser's signal light and is also amplified during the laser's amplification process, severely impacting the laser's signal-to-noise ratio and even damaging the laser.

[0042] A high-reflection grating group 4 is positioned at the output end of the pump source protector 3 along the propagation direction of the pump light to reflect high-frequency reverse light and wavelengths not covered by the pump source isolator and pump source protector. Specifically, the high-reflection grating group 4 is configured to reflect wavelengths of 1030 nm (corresponding to signal light) and wavelengths not covered by the pump source protector and isolator, such as light in the 986-1020 nm range, and light with wavelengths greater than or equal to 1120 nm, with a reflectivity of >99%. It will be appreciated that in this embodiment, by optimizing the reflection wavelength of the high-reflection grating group 4, a high-reflection grating group is formed, which reflects stray light, such as signal light, to the active optical fiber 7 for secondary use or absorption, rather than returning it directly to the laser pump 1.

[0043] A fiber combiner 5 is disposed at the output end of the highly reflective grating group 4 along the propagation direction of the pump light, so that the pump light output from the highly reflective grating group 4 can be injected into the fiber combiner 5. Furthermore, a seed source 6 is connected to the input end of the fiber combiner 5 to emit signal light toward the fiber combiner 5, thereby allowing the signal light and the pump light to be injected into the fiber combiner 5 for coupling and forming coupled light. Preferably, the wavelength emitted by the seed source 6 is typically 532 nm, 1018 nm, 1030 nm, 1064 nm, 1550 nm, 1940 nm, etc.

[0044] Active fiber 7 is disposed at the output end of fiber combiner 5 along the propagation direction of the coupled light to excite the doped ions and amplify the signal light in the coupled light. In this embodiment, active fiber 7 is a fiber doped with rare earth ions, typically ytterbium, erbium, thulium, or holmium ions.

[0045] The signal light isolator 8 is arranged at the output end of the active optical fiber 7 along the propagation direction of the coupled light, so as to isolate the signal light in the coupled light and make the signal light transmit in one direction.

[0046] In addition, in this embodiment, preferably, the laser pump 1, the pump source isolator 2, the pump source protector 3, the high-reflection grating group 4, the fiber combiner 5, the seed source 6, the active fiber 7 and the signal light isolator 8 are compactly arranged by fiber fusion or spatial optical path. Specifically, Figure 2 As shown, each optical fiber used for fiber splicing is provided with a heat sink 9 having a through-hole structure at both ends, and the two ends of the optical fiber pass through the through-holes of the corresponding heat sink 9. As a result, after the ends of two adjacent optical fibers are fused together, the heat sink 9 conducts heat to the outside, eliminating the need for additional heat dissipation or complex control structures.

[0047] Second embodiment:

[0048] like Figure 3 As shown, based on the above-mentioned first embodiment, the second embodiment of the present invention further provides a laser pump source protection device. Compared with the first embodiment, the difference of this embodiment is that a plurality of laser pump components 10 are provided.

[0049] Specifically, in this embodiment, each laser pump assembly 10 is connected to the input end of the fiber combiner 5 to provide pump light of different wavelength bands. During operation, the laser pumps 1 of different laser pump assemblies 10 can be turned on, thereby coupling pump light of different wavelength bands with the signal light to form different coupled lights.

[0050] Except for the above differences, the other structures of this embodiment are the same as those of the first embodiment and will not be described again here.

[0051] An embodiment of the present invention further provides a fiber laser, which includes the laser pump source protection device of the first embodiment or the second embodiment.

[0052] In the description of this specification, reference to the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and integrate different embodiments or examples described in this specification, as well as features of different embodiments or examples, unless otherwise inconsistent.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A laser pump source protection device, characterized in that: include: a laser pump, configured to emit pump light of a preset wavelength; A pump source isolator is provided at the output end of the laser pump along the propagation direction of the pump light, so as to block the unabsorbed mid-frequency band reverse light; A pump source protector is provided at the output end of the pump source isolator along the propagation direction of the pump light, so as to suppress low-frequency reverse light; A high-reflection grating group is arranged at the output end of the pump source protector along the propagation direction of the pump light, so as to reflect high-frequency reverse light and the band that cannot be covered by the pump source isolator and the pump source protector; an optical fiber combiner, arranged at the output end of the high-reflection grating group along the propagation direction of the pump light, for coupling the pump light and the signal light to form coupled light; a seed source connected to an input end of the optical fiber combiner, for emitting signal light toward the optical fiber combiner; an active optical fiber, arranged at the output end of the optical fiber combiner along the propagation direction of the coupled light, for exciting doped ions and amplifying the signal light in the coupled light; A signal light isolator is provided at the output end of the active optical fiber along the propagation direction of the coupled light, so as to isolate the signal light in the coupled light and enable the signal light to be transmitted in one direction.

2. The laser pump source protection device according to claim 1, characterized in that: The low-frequency band reverse light is ASE noise in a first preset band, the mid-frequency band reverse light is pump reverse light in a second preset band, and the high-frequency band reverse light is signal reverse light in a third preset band.

3. The laser pump source protection device according to claim 1, wherein: The laser pump, pump source isolator, pump source protector and high-reflection grating group together form a laser pump assembly; The laser pump source protection device includes at least two laser pump components, each of which is connected to the input end of the optical fiber combiner to provide pump light of different wavelength bands; The pump lights of different wavelength bands can be coupled with the signal light to form different coupled lights.

4. The laser pump source protection device according to claim 1, wherein: The pump source protector includes a band-stop filter, the stop band range of which covers ±50 nm of the signal light wavelength, so as to absorb low-frequency noise or reflect the low-frequency noise to an attenuation path.

5. The laser pump source protection device according to claim 1, characterized in that: The reflection wavelength of the high-reflection grating group corresponds to the wavelength of the signal light emitted by the seed source, and the reflectivity is greater than 99%.

6. The laser pump source protection device according to claim 1, characterized in that: The operating wavelength of the pump source isolator corresponds to the pump light of the preset wavelength and has a preset isolation degree, so that the isolation bandwidth range of the pump source isolator is ±10 nm of the preset wavelength of the pump light.

7. The laser pump source protection device according to claim 1, characterized in that: The high-reflection grating group reflects the high-frequency reverse light and the wavelength band that cannot be covered by the pump source isolator and the pump source protector to the active optical fiber for secondary absorption.

8. The laser pump source protection device according to claim 1, wherein: The laser pump, pump source isolator, pump source protector, high-reflection grating group, fiber combiner, seed source, active fiber and signal light isolator are compactly arranged through fiber fusion or spatial optical path.

9. The laser pump source protection device according to claim 8, characterized in that: Both ends of each optical fiber used for optical fiber fusion splicing are provided with a heat sink having a through-hole structure, so that the two ends of the optical fiber pass through the through-holes of the corresponding heat sink respectively; After the ends of two adjacent optical fibers are fused together, the heat sink is used to conduct heat to the outside.

10. A fiber laser, characterized in that: The invention comprises the laser pump source protection device according to any one of claims 1 to 9.

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