CN219203731U - Optical fiber laser and laser emission system - Google Patents
Optical fiber laser and laser emission system Download PDFInfo
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- CN219203731U CN219203731U CN202320180756.3U CN202320180756U CN219203731U CN 219203731 U CN219203731 U CN 219203731U CN 202320180756 U CN202320180756 U CN 202320180756U CN 219203731 U CN219203731 U CN 219203731U
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Abstract
The application relates to the technical field of fiber lasers, in particular to a fiber laser and a laser emission system. The optical fiber laser provided by the utility model comprises: the optical fiber laser comprises a pumping source, a forward beam combiner, an active optical fiber and a reverse beam combiner, wherein gratings are respectively arranged on two sides of the active optical fiber, each grating comprises a high-reflection grating and a low-reflection grating which are arranged in pairs, and the gratings and the active optical fiber respectively form an oscillation cavity of the optical fiber laser. The two sides of the active optical fiber are respectively provided with the gratings, and the high-reflection grating, the low-reflection grating and the active optical fiber which are arranged in pairs respectively form an oscillation cavity of the optical fiber laser, so that the whole double-cavity single-fiber structure of the laser is formed. The double-cavity single-fiber structure of the fiber laser disturbs the superposition process between longitudinal modes in the active fiber, so that the self-pulse effect in the oscillation cavity of the fiber laser is effectively inhibited, and the stimulated Raman gain in the oscillation cavity of the fiber laser is inhibited.
Description
Technical Field
The application relates to the technical field of fiber lasers, in particular to a fiber laser and a laser emission system.
Background
Stimulated raman scattering is one of the main factors limiting the increase in power of single-mode high-power fiber lasers, and suppression thereof has been the main subject of research in the field of fiber lasers.
Whether a single oscillation structure scheme or a main oscillation amplification structure scheme, the conventional adopted raman suppression modes are as follows: increasing the effective mode field area of the optical fiber, shortening the length of the optical fiber, inserting a chirped inclined grating, and the like. Wherein increasing the effective mode field area of the fiber reduces the lateral mode instability threshold of the laser system and also degrades the beam quality; shortening the length of the optical fiber easily causes insufficient total absorption of the pump light, thereby reducing the luminous efficiency of the optical fiber laser; the insertion of the chirped inclined grating can obviously improve the manufacturing cost of the system, and meanwhile, the technology maturity of the chirped inclined grating is low, the upper limit of the tolerance power is low, and single-fiber output exceeding specific power is difficult to realize.
In addition, in order to meet the industrial processing needs, the higher the power of the fiber laser, the longer the output fiber requirement of the fiber laser is. In the three modes for inhibiting the Raman gain, on the premise of a longer output optical fiber, stronger Raman gain still occurs in the output optical fiber according to a Raman gain mechanism, so that the upper power limit of the single-mode fiber laser is greatly limited. Industrial processing applications of ultra-high power single mode fiber lasers are difficult to implement.
Disclosure of Invention
The purpose of the application is to provide a fiber laser and a laser emission system, which can effectively inhibit the stimulated full gain of the fiber laser.
In order to achieve the above object, in a first aspect, the present utility model provides a fiber laser comprising: the optical fiber laser comprises a pumping source, a forward beam combiner, an active optical fiber and a reverse beam combiner, wherein gratings are respectively arranged on two sides of the active optical fiber, each grating comprises a high-reflection grating and a low-reflection grating which are arranged in pairs, and the gratings and the active optical fiber respectively form an oscillation cavity of the optical fiber laser.
In an alternative embodiment, the high reflection grating includes a first high reflection grating and a second high reflection grating disposed on the input side of the active optical fiber, and the low reflection grating includes a first low reflection grating and a second low reflection grating disposed on the output side of the active optical fiber.
In an alternative embodiment, the first high reflection grating and the first low reflection grating, and the second high reflection grating and the second low reflection grating respectively form two groups of grating pairs of the active optical fiber.
In an alternative embodiment, the active optical fiber includes a single optical fiber, and the gratings included in each group of the grating pairs are disposed on two sides of the same active optical fiber.
In an alternative embodiment, the active optical fiber, the first high reflection grating and the first low reflection grating form a first oscillation cavity of the fiber laser; and the active optical fiber, the second high-reflection grating and the second low-reflection grating form a second oscillation cavity of the optical fiber laser.
In an alternative embodiment, the output end of the second high-reflection grating is connected to the input end of the active optical fiber, and the input end of the first low-reflection grating is connected to the output end of the active optical fiber.
In an optional implementation manner, the first high reflection grating and the second high reflection grating are sequentially arranged between the forward beam combiner and the active optical fiber, and the first low reflection grating and the second low reflection grating are sequentially arranged between the active optical fiber and the backward beam combiner.
In an alternative embodiment, the two groups of grating pairs comprise a first grating pair and a second grating pair, and the reflection center wavelength of the high-reflection grating in each group of grating pairs is the same as the reflection center wavelength of the low-reflection grating;
the reflection center wavelength of the first grating pair is different from that of the second grating pair, and the reflection center wavelengths of the two groups of grating pairs are different by 10-60nm.
In an alternative embodiment, the optical fiber combiner further comprises a cladding light stripper and an output head which are sequentially arranged at the downstream of the reverse beam combiner, wherein the output head comprises a passive energy-transmitting optical fiber and a quartz end cap.
In a second aspect, the present utility model provides a laser emission system, comprising a fiber laser according to any of the preceding embodiments, the fiber laser being a seed source.
The two sides of the active optical fiber are respectively provided with the gratings, and the high-reflection grating, the low-reflection grating and the active optical fiber which are arranged in pairs respectively form an oscillation cavity of the optical fiber laser, so that the whole double-cavity single-fiber structure of the laser is formed.
The double-cavity single-fiber structure of the fiber laser disturbs the superposition process between longitudinal modes in the active fiber, so that the self-pulse effect in the oscillation cavity of the fiber laser is effectively inhibited, and the stimulated Raman gain in the oscillation cavity of the fiber laser is inhibited.
Additional features and advantages of the present application will be set forth in the detailed description which follows.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a fiber laser according to the present application;
FIG. 2 is a schematic diagram of the relationship between the forward combiner and the grating;
FIG. 3 is a schematic diagram showing the relationship between the inverse beam combiner and the grating;
FIG. 4 is a diagram showing the difference between the two sets of gratings versus the reflected center wavelength;
fig. 5 is a schematic structural diagram of a laser emission system in the present application.
Icon:
10-a pump source; 20-forward combiner; 30-reversing the beam combiner; 31-signal optical fiber; 41-a first high reflection grating; 42-a first low reflection grating; 51-a second high reflection grating; 52-a second low reflection grating; 60-active optical fiber; 70-a cladding light stripper; 80-an output head; 81-passive energy-transfer optical fiber; 82-quartz end caps; 90-seed source.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It will be apparent that the embodiments described are some, but not all, of the embodiments of the present application. The components of the embodiments of the present application, which are generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations.
In the description of the present application, it should be noted that, the azimuth or positional relationship indicated by the terms "inner", "outer", etc. are based on the azimuth or positional relationship shown in the drawings, or the azimuth or positional relationship that is commonly put when the product of the application is used, are merely for convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
In the description of the present application, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.
The fiber laser is mainly used for inhibiting stimulated full gain in the optical fiber and is beneficial to improving the power of the single-mode fiber laser.
Referring to the structure of the fiber laser in fig. 1, the fiber laser includes a pump source 10, a forward combiner 20, a first high reflection grating 41, a second high reflection grating 51, an active fiber 60, a first low reflection grating 42, a second low reflection grating 52, a backward combiner 30, a cladding light stripper 70, and an output head 80, which are sequentially disposed.
Through the high reflection grating and the low reflection grating which are arranged at the two sides of the active optical fiber 60 and the active optical fiber 60 which is combined between the high reflection grating and the low reflection grating, a single-fiber double-cavity structure of the fiber laser can be formed, longitudinal mode superposition can be effectively disturbed, self-pulse generation is inhibited, laser peak power in an oscillation cavity is reduced, and stimulated Raman threshold is improved.
Specifically, the first high reflection grating 41 and the second high reflection grating 51 are disposed on the input side of the active optical fiber 60, and the first low reflection grating 42 and the second low reflection grating 52 are disposed on the output side of the active optical fiber 60.
Further, the first high reflection grating 41 and the first low reflection grating 42, and the second high reflection grating 51 and the second low reflection grating 52 respectively form two groups of grating pairs of the active optical fiber 60, and the active optical fiber 60 comprises a single optical fiber arranged between each group of grating pairs, so that the high reflection grating and the low reflection grating included in each group of grating pairs are arranged on two sides of the same active optical fiber 60.
Preferably, the first high reflection grating 41 and the second high reflection grating 51 are etched on the same active optical fiber 60, and the active optical fiber 60 is used as a single optical fiber of the forward combiner 20, so that the insertion loss and the heat damage hidden danger caused by the fusion welding of the active optical fibers 60 are avoided.
Similarly, it is preferable that the first low reflection grating 42 and the second low reflection grating 52 are etched on the same active optical fiber 60, and the active optical fiber 60 is used as a single optical fiber of the reverse combiner 30, so as to avoid the insertion loss and the thermal damage hidden trouble caused by the fusion welding of the active optical fibers 60.
The oscillation cavity formed by the two groups of grating pairs and the active optical fiber 60 specifically comprises a first oscillation cavity and a second oscillation cavity, and specifically, the active optical fiber 60, the first high reflection grating 41 and the first low reflection grating 42 form a first oscillation cavity of the fiber laser; the active optical fiber 60, the second high reflection grating 51 and the second low reflection grating 52 form a second oscillation cavity of the optical fiber laser, so that the optical fiber laser forms an integral single-fiber double-cavity structure.
Further, the output end of the second high reflection grating 51 is connected to the input end of the active optical fiber 60, and the input end of the first low reflection grating 42 is connected to the output end of the active optical fiber 60, so as to form an oscillator with two oscillation cavities.
Preferably, the first high reflection grating 41 and the second high reflection grating 51 are sequentially disposed between the forward combiner 20 and the active optical fiber 60, and the first low reflection grating 42 and the second low reflection grating 52 are sequentially disposed between the active optical fiber 60 and the backward combiner 30.
In the existing single oscillation cavity structure, stable longitudinal mode superposition is easy to form because of the fixed cavity length of the single cavity structure in the oscillation cavity, so that self-pulse is generated, the laser peak power in the oscillation cavity is improved, and the stimulated Raman threshold is lower.
When the same active optical fiber 60 is provided with a plurality of oscillation cavities, the longitudinal mode superposition is effectively disturbed, the generation of self-pulse is restrained, the laser peak power in the oscillation cavities is reduced, and the stimulated Raman threshold is higher.
By adopting the single-fiber double-cavity structure mode, the superposition process of longitudinal modes in the active optical fiber 60 can be disturbed, the self-pulse effect in the oscillation cavity of the optical fiber laser is effectively inhibited, and the stimulated Raman gain in the oscillation cavity of the optical fiber laser is inhibited.
In the utility model, the pump source 10 of the fiber laser outputs pump light, and the forward beam combiner 20 and the backward beam combiner 30 combine the pump light output by the pump sources 10 into the same active fiber 60 in a fusion mode. The active optical fiber 60 is a medium that absorbs pump light to generate laser light, wherein the absorption spectrum of the rare earth doped particles covers the pump light wavelength range.
Downstream of the inverse combiner 30, a cladding light stripper 70 and an output head 80 are provided in this order, the output head 80 comprising a passive energy-conducting optical fiber 81 and a quartz end cap 82.
Referring to fig. 2-3, further, a cladding light stripper 70 is fused behind the signal fiber 31 at the fiber bundle end of the reverse combiner 30, and an output head 80 comprising a passive energy-transmitting fiber 81 and a quartz end cap 82 is fused downstream of the cladding light stripper 70.
In another specific embodiment, the two grating pairs include a first grating pair and a second grating pair, and the reflection center wavelength of the high reflection grating in each grating pair is the same as the reflection center wavelength of the low reflection grating;
the reflection center wavelength of the first grating pair is different from the reflection center wavelength of the second grating pair, and the reflection center wavelengths of the two groups of grating pairs are different by 10-60nm.
Specifically, the first high reflection grating 41 and the first low reflection grating 42 form a first grating pair, and the reflection center wavelength of the first high reflection grating 41 is identical to the reflection center wavelength of the first low reflection grating 42, and is λ c1 The method comprises the steps of carrying out a first treatment on the surface of the The reflection center wavelength of the second high reflection grating 51 is identical to the reflection center wavelength of the second low reflection grating 52, and is lambda c2 。
Wherein lambda is c1 And lambda (lambda) c2 For different values, the two differ by 10nm-60nm, lambda c1 And lambda (lambda) c2 The values of (2) lie within the emission spectrum of the rare earth particles doped with the active optical fiber 60.
For a particular matrix of active fibers 60, the difference between the laser center wavelength and its corresponding raman center wavelength is constant, preferably, the active fibers 60 employ a quartz matrix, which difference is about 54nm.
When the output reflection center wavelength of the first oscillating cavity is lambda c1 Setting the corresponding Raman center wavelength as λR c1 ＝λ c1 +54nm, its Raman stimulated amplification threshold in the passive energy-transfer fiber 81 is P thR1 。
Similarly, when the output center wavelength of the second oscillation cavity is lambda c2 Setting the corresponding Raman center wavelength as λR c2 ＝λ c2 +54nm, its Raman stimulated amplification threshold in the passive energy-transfer fiber 81 is P thR2 The wavelength is shown in fig. 4.
When lambda is c1 And lambda (lambda) c2 When the difference value of the two is 10nm-60nm, the Raman light generated by the two can not form linear superposition, as long as the power P output by the first oscillation cavity is maintained 1 <P thR1 At the same time the power P output by the second oscillating cavity 2 <P thR2 Even if the total output power p=p1+p2 is far greater than the output power at a single wavelength, the raman stimulated amplification does not occur in the passive energy-transmitting fiber 81 and the index is not obtainedWith the addition, the phase change increases the upper power limit of the laser system and suppresses the gain of the raman light.
The combination adopts the structure mode of double-cavity single fiber, so that the fiber laser outputs laser with two wavelengths, the spectral density of the laser in the passive energy-transmitting fiber 81 is reduced, when the laser power of each wavelength is controlled to be lower than the Raman stimulated amplification threshold power, the total output power can be higher than the upper power limit of any single-wavelength output, and the Raman stimulated amplification in the passive energy-transmitting fiber 81 is inhibited.
Referring to fig. 5, the present utility model further provides a laser emission system, which includes the optical fiber laser with the dual-cavity single-fiber structure, and by using the optical fiber laser as the seed source 90, amplification of dual-wavelength laser can be achieved, and the raman stimulated amplification threshold of the laser amplification stage can be effectively improved.
The fiber laser and the laser emission system can realize the obvious improvement of output power and synchronously inhibit the Raman stimulated gain while the energy-transfer fiber is long enough without basically changing the beam quality of the laser.
The brightness of the fiber laser can be improved under the condition of keeping the specification of the laser fiber unchanged, and multimode beam combination is facilitated.
It should be noted that, without conflict, features in the embodiments of the present application may be combined with each other.
The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims (10)
1. A fiber laser, comprising: the optical fiber laser comprises a pumping source, a forward beam combiner, an active optical fiber and a reverse beam combiner, wherein gratings are respectively arranged on two sides of the active optical fiber, each grating comprises a high-reflection grating and a low-reflection grating which are arranged in pairs, and the gratings and the active optical fiber respectively form an oscillation cavity of the optical fiber laser.
2. The fiber laser of claim 1, wherein the high reflection grating comprises a first high reflection grating and a second high reflection grating disposed on the input side of the active fiber, and the low reflection grating comprises a first low reflection grating and a second low reflection grating disposed on the output side of the active fiber.
3. The fiber laser of claim 2, wherein the first high reflection grating and the first low reflection grating, and the second high reflection grating and the second low reflection grating form two sets of grating pairs of the active fiber, respectively.
4. A fibre laser as claimed in claim 3 wherein the active fibre comprises a single fibre and each of the grating pairs comprises gratings disposed on either side of the same active fibre.
5. The fiber laser of claim 3, wherein the active fiber and the first high reflection grating and the first low reflection grating form a first oscillation cavity of the fiber laser; and the active optical fiber, the second high-reflection grating and the second low-reflection grating form a second oscillation cavity of the optical fiber laser.
6. A fiber laser as claimed in claim 3 wherein the output end of the second high reflection grating is connected to the input end of the active fiber and the input end of the first low reflection grating is connected to the output end of the active fiber.
7. The fiber laser of claim 3, wherein the first high reflection grating and the second high reflection grating are disposed in sequence between the forward combiner and the active fiber, and the first low reflection grating and the second low reflection grating are disposed in sequence between the active fiber and the backward combiner.
8. A fiber laser as claimed in claim 3 wherein the two sets of grating pairs comprise a first grating pair and a second grating pair, each set of the grating pairs having a reflection center wavelength of the high reflection grating that is the same as the reflection center wavelength of the low reflection grating;
the reflection center wavelength of the first grating pair is different from that of the second grating pair, and the reflection center wavelengths of the two groups of grating pairs are different by 10-60nm.
9. A fiber laser as claimed in claim 3 further comprising a cladding light stripper and an output head disposed in sequence downstream of the reverse combiner, the output head comprising a passive energy-conducting fiber and a quartz end cap.
10. A laser emitting system comprising the fiber laser of any of claims 1-9 as a seed source.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202320180756.3U CN219203731U (en) | 2023-01-19 | 2023-01-19 | Optical fiber laser and laser emission system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202320180756.3U CN219203731U (en) | 2023-01-19 | 2023-01-19 | Optical fiber laser and laser emission system |
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| CN219203731U true CN219203731U (en) | 2023-06-16 |
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| CN202320180756.3U Active CN219203731U (en) | 2023-01-19 | 2023-01-19 | Optical fiber laser and laser emission system |
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