CN115603162B - Method and system for improving stimulated Brillouin scattering threshold of fiber laser - Google Patents
Method and system for improving stimulated Brillouin scattering threshold of fiber laser Download PDFInfo
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- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/30—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects
- H01S3/302—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects in an optical fibre
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Abstract
The invention provides a method and a system for improving stimulated Brillouin scattering threshold of a fiber laser. According to the method, laser emitted by a laser is regulated and controlled into first polarized light and second polarized light which are mutually orthogonal according to a preset time interval through a polarization control system, so that the first polarized light and the second polarized light are alternately transmitted, the polarization states of the polarized light and backward Stokes light are mutually orthogonal to reduce stimulated Brillouin scattering gain, and the threshold value of stimulated Brillouin scattering of the fiber laser is improved. According to the invention, the first backward Stokes light and the second polarized light generated by the first polarized light can not generate SBS gain, and the second backward Stokes light and the first polarized light generated by the second polarized light can not generate SBS gain by alternately transmitting the first polarized light and the second polarized light which are mutually orthogonal, so that the energy of the backward Stokes light is intermittently increased instead of continuously increased, and the SBS threshold of the fiber laser is improved.
Description
Technical Field
The invention relates to the technical field of fiber lasers, in particular to a method and a system for improving a stimulated Brillouin scattering threshold of a fiber laser.
Background
Under the promotion of fields such as beam synthesis, coherent radar, nonlinear frequency conversion and the like, the high-power narrow-linewidth linearly polarized fiber laser technology is continuously broken through. The high-power narrow-linewidth linearly polarized fiber laser has longer fiber length and smaller fiber core sectional area, and various nonlinear effects can be easily generated after the transmission power of the laser reaches a certain level. Among the various nonlinear effects, the threshold of Stimulated Brillouin Scattering (SBS) is the lowest and is currently the main factor limiting the further increase in power of high-power narrow-linewidth linearly polarized fiber lasers.
There are three main ways to raise the SBS threshold: increasing the effective mode field area of the optical fiber, reducing the effective length of the optical fiber and reducing the SBS gain factor. The increase of the effective mode field area of the optical fiber and the decrease of the effective length of the optical fiber can strengthen The Mode Instability (TMI) effect of the optical fiber laser while inhibiting the SBS effect, which is not beneficial to the improvement of the power of the laser; reducing the SBS gain factor becomes the primary method of increasing the SBS threshold. Researchers have conducted a great deal of research on changing the stimulated brillouin gain spectrum to inhibit the SBS effect, and have proposed a plurality of methods of widening the seed laser linewidth, applying temperature, stress gradient, and sound field clipping through phase modulation operation, but the SBS effect is still the biggest technical bottleneck for improving the power of a narrow linewidth fiber laser.
The mechanism of the SBS effect is that the backward Stokes light (backward Stokes light) is excited after the high-intensity signal light is transmitted, and interference occurs between the backward Stokes light and the forward signal light, and an acoustic wave is generated, and the acoustic wave further excites the backward Stokes light to exponentially increase. It is well known that the SBS effect is closely related to the polarization direction of laser light: when the polarization states of the signal light (i.e., the laser light emitted by the laser) and the backward Stokes light (generated due to the SBS effect of the laser light) are the same, the SBS gain is maximized, so that the SBS threshold is minimized; when the polarization states of the signal light and the backward Stokes light are orthogonal, the SBS gain is zero, so that the SBS threshold value is improved, the SBS effect of the polarization maintaining system is strongest (the polarization states of the signal light and the backward Stokes light of the polarization maintaining system are the same), and further, it is difficult to output high-power narrow-linewidth linear polarized laser.
Researchers have proposed that the linear polarized signal light is incident into the polarization maintaining fiber at 45 ° to reduce the SBS gain, however, the result shows that the SBS threshold is not significantly raised by using 45 ° fusion to make the linear polarized signal light incident into the polarization maintaining fiber amplifier at 45 °. The reason for this is that after the signal light enters the polarization maintaining fiber at 45 °, the polarization states of the generated backward Stokes light tend to meet the signal light in the reverse transmission process, so that the polarization states of the backward Stokes light and the signal light tend to be the same, and the SBS gain is increased, so that the SBS threshold is not obviously raised.
The CA2342538C patent provides an optical fiber transmission system for reducing SBS effect, which divides incident light into p-light and s-light with time delay (breaks the coherence between the p-light and the s-light), and although the SBS threshold of the laser can theoretically increase by 2 times, the output light of the system is unpolarized light, which cannot meet the application requirements of some linear polarized high-power lasers. Based on this patent, the application number US8995049B2 provides a method and apparatus for suppressing the SBS effect using polarization control with a birefringent retardation element, by adding a coherence compensation device at the output to re-restore the output light to linearly polarized light, but the optical retardation line it employs must be placed in the main optical path at the output of the amplifier, which undoubtedly increases the effective fiber length of the amplifier, and the SBS threshold boosting effect will be greatly compromised when the system linewidth is very narrow.
In view of the foregoing, there is a need for an improved method and system for raising the stimulated brillouin scattering threshold of a fiber laser.
Disclosure of Invention
The invention aims to provide a method and a system for improving the stimulated Brillouin scattering threshold of a fiber laser, wherein laser emitted by the laser is regulated and controlled into first polarized light and second polarized light which are mutually orthogonal according to a preset time interval by a polarization control system, the first polarized light and the second polarized light are transmitted alternately, and in the process of alternately transmitting the first polarized light and the second polarized light forwards, first backward Stokes light and second polarized light generated by the first polarized light are in a mutually orthogonal state, and SBS gain (namely, SBS gain is zero) is not generated by the first backward Stokes light and the second polarized light; similarly, the second backward Stokes light generated by the second polarized light and the first polarized light are in a mutually orthogonal state, and the second backward Stokes light and the first polarized light cannot generate SBS gain, so that the energy of the backward Stokes light is intermittently increased, but not continuously increased, the SBS gain of laser emitted by the laser can be effectively reduced, and the SBS threshold of the fiber laser is improved.
In order to achieve the above-mentioned object, the present invention provides a method for raising the stimulated brillouin scattering threshold of an optical fiber laser, in which laser light emitted by the optical fiber laser is modulated into first polarized light and second polarized light orthogonal to each other at preset time intervals by a polarization control system, so that the first polarized light and the second polarized light are transmitted alternately, and the polarization states of the polarized light and backward stokes light are ensured to be orthogonal to each other so as to reduce the stimulated brillouin scattering gain, thereby raising the stimulated brillouin scattering threshold of the optical fiber laser.
In order to achieve the above object, the present invention further provides a system for raising the stimulated brillouin scattering threshold of an optical fiber laser, which is configured to implement the above method for raising the stimulated brillouin scattering threshold of an optical fiber laser, including a laser, a first polarization control system, an optical fiber collimating end cap, and a second polarization control system that are sequentially connected, wherein laser emitted by the laser generates first polarized light and second polarized light that are orthogonal to each other at a predetermined time interval after being regulated by the first polarization control system, so that the first polarized light and the second polarized light are alternately transmitted to the optical fiber collimating end cap, and the first polarized light or the second polarized light is output through the optical fiber collimating end cap, and is reduced to linear polarized light by the second polarization control system and then output.
As a further improvement of the invention, an optical fiber laser pre-amplification stage and an optical fiber laser main amplification stage are arranged between the first polarization control system and the optical fiber collimation end cap, and polarized light regulated and controlled by the first polarization control system is subjected to power amplification primarily through the optical fiber laser pre-amplification stage and then subjected to power amplification again through the optical fiber laser main amplification stage, so that a high-power optical fiber is obtained.
As a further improvement of the invention, a phase adjusting component is arranged between the laser and the first polarization control system and is used for widening the spectrum of laser emitted by the laser, so that the stimulated Brillouin scattering gain is reduced, and the threshold value of stimulated Brillouin scattering of the optical fiber laser is improved.
As a further improvement of the invention, a high-power polarization-preserving annular isolator is arranged between the fiber laser pre-amplification stage and the fiber laser main amplification stage and is used for transmitting forward propagating polarized light and conducting backward Stokes light which is transmitted in the opposite direction to a third port of the annular isolator which is not connected with a main light path.
As a further improvement of the invention, a stimulated Brillouin scattering power detector is connected to the third port of the annular isolator and is used for detecting the power change of backward Stokes light so as to judge whether the laser of the main amplification stage of the fiber laser reaches a stimulated Brillouin scattering threshold.
As a further improvement of the invention, the optical signal output end of the second polarization control system is provided with a main power meter for detecting the power of polarized light output from the second polarization control system.
As a further improvement of the present invention, the first polarization control system and the second polarization control system are each composed of a piezoelectric polarization controller and a signal generator; the piezoelectric polarization controller is one of an azimuth polarization controller and a retardation polarization controller.
As a further improvement of the invention, the laser is a linear polarization single frequency fiber laser, and the linear polarization single frequency fiber laser is one of a distributed feedback laser or a single frequency ring laser.
As a further improvement of the present invention, the laser light emitted by the laser is one of a continuous laser light or a pulsed laser light.
The beneficial effects of the invention are as follows:
(1) According to the method for improving the stimulated Brillouin scattering threshold of the fiber laser, laser emitted by the laser is regulated and controlled into the first polarized light and the second polarized light which are mutually orthogonal according to the preset time interval through the polarization control system, the first polarized light and the second polarized light are transmitted alternately, and in the process of alternately transmitting the first polarized light and the second polarized light forwards, the first backward Stokes light and the second polarized light generated by the first polarized light are in a mutually orthogonal state, and SBS gain (namely, SBS gain is zero) is not generated between the first backward Stokes light and the second polarized light; similarly, the second backward Stokes light generated by the second polarized light and the first polarized light are in a mutually orthogonal state, and the second backward Stokes light and the first polarized light do not generate SBS gain; the backward Stokes light can be strengthened only when encountering polarized light with the same polarization state, but the energy is not strengthened when encountering polarized light orthogonal with the polarization state, and the energy is strengthened until encountering the next polarized light with the same polarization state, so that the energy of the backward Stokes light is discontinuously increased, but not continuously increased, and the SBS gain of laser emitted by the laser can be effectively reduced in such a way that the SBS threshold of the optical fiber laser is improved.
(2) According to the system for improving the stimulated Brillouin scattering threshold of the fiber laser, provided by the invention, the phase adjustment component is arranged to adjust the phase of laser emitted by the laser, so that the spectrum of the laser is widened, and the SBS gain is primarily reduced. By arranging the first polarization control system, the laser generates first polarized light and second polarized light which are mutually orthogonal according to a preset time interval, and the first polarized light and the second polarized light are alternately transmitted forwards, so that the possibility of enhancing the energy of the backward Stokes light caused by interference of the forward transmitted polarized light and the backward Stokes light is fundamentally reduced, and the SBS gain is reduced. The power of polarized light is amplified in multiple stages by arranging the optical fiber laser pre-amplification stage and the optical fiber laser main amplification stage, so that the power of output laser is further improved. The high power laser is reduced to a linearly polarized laser output by providing a first polarization control system. Therefore, through the synergistic effect of all the components in the system, the SBS gain is reduced, the SBS threshold is improved, and the output of high-power narrow-linewidth linear polarization laser is realized. The system provides a simple and effective solution for breaking through the bottleneck in the process of improving the output power of the laser.
Drawings
Fig. 1 is a schematic structural diagram of a system for raising the stimulated brillouin scattering threshold of a fiber laser according to the present invention.
Fig. 2 is a schematic diagram of stimulated brillouin scattering effect generated by polarized light in the optical transmission process by using the method for raising the stimulated brillouin scattering threshold of the fiber laser.
Reference numerals
1-a laser; 2-a first polarization control system; 3-fiber collimating end caps; 4-a second polarization control system; 5-a fiber laser pre-amplification stage; 6-a main amplification stage of the fiber laser; 7-a phase adjustment assembly; 8-ring-shaped spacers; 9-stimulated brillouin scattering power detector; 10-output power detector.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.
It should be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and/or processing steps closely related to aspects of the present invention are shown in the drawings, and other details not greatly related to the present invention are omitted.
In addition, it should be further noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention provides a method for improving stimulated Brillouin scattering threshold of a fiber laser, which comprises the steps of regulating and controlling laser emitted by the laser into first polarized light and second polarized light which are mutually orthogonal according to a preset time interval through a polarization control system, enabling the first polarized light and the second polarized light to be transmitted alternately, enabling the first polarized light transmitted forward to generate first backward Stokes light (backward Stokes light) transmitted reversely (i.e. transmitted backward), and enabling the second polarized light transmitted forward to generate second backward Stokes light transmitted reversely. In this way, in the process of alternately transmitting the first polarized light and the second polarized light forwards, the first backward Stokes light generated by the first polarized light and the second polarized light are in a mutually orthogonal state, and the first backward Stokes light and the second polarized light cannot generate Stimulated Brillouin Scattering (SBS) gain (that is, SBS gain is zero); similarly, the second backward Stokes light generated by the second polarized light and the first polarized light are in a mutually orthogonal state, and neither of them generates SBS gain. Therefore, in the forward transmission process of polarized light (first polarized light and second polarized light), the backward Stokes light can be strengthened only when encountering polarized light with the same polarization state, but the energy is not strengthened when encountering polarized light orthogonal to the polarization state, and the energy is strengthened until encountering the polarized light with the same polarization state of the next section, so that the energy of the backward Stokes light is discontinuously increased rather than continuously increased.
Referring to fig. 1, the invention further provides a system for increasing the stimulated brillouin scattering threshold of the fiber laser, which is used for realizing the method for increasing the stimulated brillouin scattering threshold of the fiber laser. The system for improving the stimulated Brillouin scattering threshold of the fiber laser is a full polarization maintaining fiber laser system and comprises a laser 1, a first polarization control system 2, a fiber collimation end cap 3 and a second polarization control system 4 which are connected in sequence. So set up, after the periodic regulation and control of the first polarization control system 2 of laser 1 launched, produce first polarized light and second polarized light (first polarized light and second polarized light can keep its original polarization state in the subsequent polarization maintaining optical fiber) orthogonal to each other according to the preset time interval, make first polarized light and second polarized light transmit to the optical fiber collimation end cap 3 alternately, first polarized light or second polarized light is output through the optical fiber collimation end cap 3, reduced to the linear polarized light by the second polarization control system 4 and output.
Specifically, the laser 1 is a linear polarization single-frequency fiber laser, which is one of a distributed feedback laser or a single-frequency ring laser. The wavelength of the laser light emitted from the laser 1 varies depending on the type of the laser 1 selected, and the wavelength of the laser light emitted from the laser 1 is 1 to 2 μm. In addition, the laser light emitted from the laser 1 is one of continuous laser light and pulsed laser light.
The first polarization control system 2 and the second polarization control system 4 are both composed of a piezoelectric polarization controller and a signal generator; the piezoelectric polarization controller is one of an azimuth polarization controller and a retardation polarization controller. As shown in fig. 1, the piezoelectric polarization controller is disposed in the main optical path, the signal generator adjusts the working state of the piezoelectric polarization controller by means of a preset encoding program inside the signal generator, specifically, a required program is encoded in the signal generator, and the program is transferred to the piezoelectric polarization controller connected with the signal generator, and then the laser polarization state is controlled by the piezoelectric polarization controller.
In this embodiment, the first polarized light alternately output by the first polarization control system 2 is p light, and the second polarized light is s light, so that the output time interval between the p light and the s light is ensured to be less than the time of transmitting the photons once in the whole optical fiber system. Preferably, the output time of p-light and s-light is set at 1:1 each time, i.e. the output time interval of p-light and s-light is the same. As shown in fig. 2, the energy of the backward Stokes light increases discontinuously, rather than continuously.
As shown in fig. 1, a phase adjusting component 7 is disposed between the laser 1 and the first polarization control system 2, and is used for expanding the spectrum of the laser light emitted by the laser 1 from the source, so as to increase the spectrum width of the SBS gain, reduce the SBS gain, and increase the SBS threshold of the fiber laser.
An optical fiber laser pre-amplification stage 5 and an optical fiber laser main amplification stage 6 are arranged between the first polarization control system 2 and the optical fiber collimation end cap 3, and polarized light regulated and output by the first polarization control system 2 is subjected to primary power amplification through the optical fiber laser pre-amplification stage 5 and then subjected to secondary power amplification through the optical fiber laser main amplification stage 6, so that high-power optical fiber is obtained.
Semiconductor pump source laser with wavelength of 900-1100 nm, preferably 915nm or 976nm, and 1018nm pump source laser for pump laser of fiber laser pre-amplifying stage 5 and fiber laser main amplifying stage 6
A high-power polarization-preserving ring isolator 8 is arranged between the fiber laser pre-amplification stage 5 and the fiber laser main amplification stage 6, and is used for transmitting forward-propagating polarized light and conducting backward-propagating Stokes light to a third port (three ports are arranged on the ring isolator 8, a first port and a second port are connected into the main optical path, and the third port is not connected into the main optical path) of the ring isolator 8, specifically, an output end of the fiber laser pre-amplification stage 5 is connected into the first port of the ring isolator 8, a second port of the ring isolator 8 is connected into an input end of the fiber laser main amplification stage 6, and an optical signal is input from the first port of the ring isolator 8 and output from the second port. Meanwhile, a stimulated brillouin scattering power detector 9 is connected to a third port of the annular isolator 8, and is configured to detect a power change of backward Stokes light, so as to determine whether laser emitted by the fiber laser main amplifying stage 6 reaches an SBS threshold. Specifically, the polarized light continuously generates backward Stokes light in the forward transmission process, the backward Stokes light in the backward transmission process is coupled and output through the third port of the annular isolator 8, and the signal is transmitted to the stimulated brillouin scattering power detector 9 connected with the annular isolator 8; when the stimulated brillouin scattering power detector 9 detects that the power of the backward Stokes light increases exponentially, it is indicated that the laser light of the fiber laser main amplifying stage 6 reaches the SBS threshold.
In some embodiments, the optical signal output of the second polarization control system 4 is provided with an output power detector 10 for detecting the power of the polarized light output from the second polarization control system 4.
The working principle of the system for improving the stimulated Brillouin scattering threshold of the fiber laser is as follows: the laser emitted by the laser 1 passes through the phase adjusting component 7 to adjust the phase of the laser, so that the spectrum of the laser is widened, and the reduction of the SBS gain is primarily realized. Then, the laser with the spectrum spread enters the first polarization control system 2, at the moment, a preset coding program in the signal generator is transmitted to the piezoelectric polarization controller, the control of the polarization state of the laser is realized through the piezoelectric polarization controller, the laser generates first polarized light and second polarized light which are mutually orthogonal at preset time intervals, and the first polarized light and the second polarized light are alternately transmitted forwards. The forward transmitted polarized light passes through the optical fiber laser pre-amplification stage 5 to realize power amplification initially, and then enters the optical fiber laser main amplification stage 6 through the annular isolator 8 to realize power re-amplification so as to obtain the high-power optical fiber. Polarized light output from the fiber laser main amplifying stage 6 passes through the fiber collimating end cap 3, and the fiber collimating end cap 3 reduces the power density of the output end of the output light beam by expanding the output light beam, so that the end face of the fiber is prevented from being burnt. The polarized light output from the optical fiber collimation end cap 3 passes through the second polarization control system 4, and the high-power laser alternately output by the first polarized light and the second polarized light is reduced into linear polarized laser by the second polarization control system 4, so that high-power narrow linewidth linear polarized laser output is realized; finally, the output power detector 10 detects the power of the output laser beam. In the process of continuously transmitting the polarized light forwards, backward Stokes light is continuously generated, the backward Stokes light transmitted in the reverse direction is coupled and output through a third port of the annular isolator 8, the signal is transmitted to the stimulated brillouin scattering power detector 9 connected with the annular isolator 8, and when the stimulated brillouin scattering power detector 9 detects that the power of the backward Stokes light increases exponentially, the laser of the fiber laser main amplifying stage 6 reaches the SBS threshold value. The system for improving the stimulated Brillouin scattering threshold of the fiber laser can realize multistage power amplification of incident laser, and the amplification stage number is not limited.
In summary, according to the method and the system for improving the stimulated brillouin scattering threshold of the fiber laser provided by the invention, the polarization control system regulates and controls the laser emitted by the laser into the first polarized light and the second polarized light which are mutually orthogonal according to the preset time interval, meanwhile, the first polarized light and the second polarized light are alternately transmitted, and in the process of alternately transmitting the first polarized light and the second polarized light forwards, the first backward Stokes light and the second polarized light generated by the first polarized light are in a mutually orthogonal state, and the first backward Stokes light and the second polarized light cannot generate SBS gain (namely, the SBS gain is zero); similarly, the second backward Stokes light generated by the second polarized light and the first polarized light are in a mutually orthogonal state, and the second backward Stokes light and the first polarized light cannot generate SBS gain, so that the energy of the backward Stokes light is intermittently increased, but not continuously increased, the SBS gain of laser emitted by the laser can be effectively reduced, and the SBS threshold of the fiber laser is improved; the system provides a simple and effective solution for breaking through the bottleneck in the process of improving the output power of the laser.
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present invention.
Claims (2)
1. The system for improving the stimulated Brillouin scattering threshold of the fiber laser is characterized by comprising a laser, a phase adjusting component, a first polarization control system, a fiber laser pre-amplification stage, a high-power polarization-maintaining annular isolator, a fiber laser main amplification stage, a fiber collimation end cap and a second polarization control system which are connected in sequence;
the first polarization control system and the second polarization control system are both composed of a piezoelectric polarization controller and a signal generator; the first polarization control system alternately outputs first polarized light and second polarized light which are mutually orthogonal according to the output time ratio of 1:1;
the high-power polarization-maintaining annular isolator is used for transmitting forward-propagating polarized light and transmitting backward-propagating Stokes light to a third port of the annular isolator, which is not connected with a main light path; the third port of the annular isolator is connected with an stimulated Brillouin scattering power detector which is used for detecting the power change of backward Stokes light so as to judge whether the laser of the main amplification stage of the fiber laser reaches a stimulated Brillouin scattering threshold value or not;
the optical signal output end of the second polarization control system is provided with an output power detector for detecting the power of polarized light output from the second polarization control system;
the laser emitted by the laser device is subjected to phase adjustment through the phase adjustment component to widen the spectrum, and then is regulated and controlled by the first polarization control system to generate first polarized light and second polarized light which are mutually orthogonal according to a preset time interval, the first polarized light and the second polarized light are alternately transmitted to the fiber laser pre-amplification stage to preliminarily realize power amplification, and then enter the fiber laser main amplification stage through the annular isolator to realize power re-amplification so as to obtain a high-power optical fiber; then the obtained high-power optical fiber is output through the optical fiber collimation end cap, and is restored into linearly polarized light by the second polarization control system and then output;
the laser is a linear polarization single-frequency optical fiber laser, and the linear polarization single-frequency optical fiber laser is one of a distributed feedback laser or a single-frequency ring laser; the laser emitted by the laser is one of continuous laser or pulse laser.
2. The system for increasing the stimulated brillouin scattering threshold of a fiber laser of claim 1, wherein the piezoelectric polarization controller is one of an azimuthal polarization controller or a retardation polarization controller.
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