CN116154593A - Device, system and method for realizing mode self-cleaning of multimode optical fiber amplifier - Google Patents
Device, system and method for realizing mode self-cleaning of multimode optical fiber amplifier Download PDFInfo
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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
- H01S3/10007—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers
- H01S3/10015—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers by monitoring or controlling, e.g. attenuating, the input signal
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
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- H01S3/10007—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers
- H01S3/10023—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers by functional association of additional optical elements, e.g. filters, gratings, reflectors
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Abstract
The invention discloses a device, a system and a method for realizing mode self-cleaning of a multimode fiber amplifier, wherein the device comprises a laser beam splitting module, a graded index gain fiber amplifier, a laser beam splitting mirror, a laser mode analysis device and a feedback module; the laser beam splitting module splits the seed light into signal light and auxiliary light; the graded index gain optical fiber amplifier amplifies signal light and auxiliary light; the laser beam splitter splits the amplified signal light and auxiliary light; the laser mode analysis device outputs various mode information; the feedback module generates power feedback information according to the mode information and outputs the power feedback information to the laser beam splitting module; and the laser beam splitting module is used for carrying out power proportion adjustment on the power of the signal light and the power of the auxiliary light according to the power feedback information, and the laser beam splitting lens is used for outputting target laser with the power proportion adjusted. The invention can adjust the power ratio of the signal light and the auxiliary light, realize the mode self-cleaning and improve the quality of the output light beam.
Description
Technical Field
The invention relates to the technical field of fiber lasers, in particular to a device, a system and a method for realizing mode self-cleaning of a multimode fiber amplifier.
Background
Multimode fibers typically play a role in low brightness pump laser coupling and beam transmission in high average power, high peak power fiber lasers. In some applications insensitive to the quality of the light beam, the multimode fiber amplifier is not easy to accumulate time domain-frequency domain nonlinear effects due to high bearing power density, and is becoming an indispensable tool in the fields of industrial processing, basic science and laser communication. However, the laser mode output by the multimode gain fiber is a mixture of a plurality of laser transverse modes, which limits the application of the multimode gain fiber in the fields of precision machining, ultra-short pulse amplification and next-generation laser communication. The transverse mode transmission mode of the graded-index fiber is affected by the nonlinear effect of the fiber, particularly the kerr effect, and the self-cleaning characteristic is shown at high peak power, namely, the duty ratio of the fundamental transverse mode can be improved in the multimode graded-index fiber by increasing the laser peak power. However, the transmission mode self-cleaning effect exhibits a threshold characteristic that is related to the laser peak power. Currently, single-mode laser with high peak power is transmitted in a multimode graded index optical fiber, and the beam quality of the output laser can be improved by utilizing the mode self-cleaning effect, and even the near diffraction limit is reached. However, when amplifying using a doped multimode graded index fiber as a gain medium, the higher order modes are excited during signal light amplification, limiting the duty cycle of the fundamental transverse mode of the amplified laser light, ultimately resulting in degradation of the output beam quality.
Therefore, in view of the above-mentioned problems, it is an urgent need in the industry to find a method for achieving mode self-cleaning in a multimode graded fiber amplifier, and to be able to be used in high peak power laser systems.
Disclosure of Invention
The invention aims to overcome the defects of the background technology, and provides a device, a system and a method for realizing the mode self-cleaning of a multimode optical fiber amplifier, which are used for adjusting the power ratio of signal light and auxiliary light, realizing the mode self-cleaning and improving the quality of an output light beam.
In a first aspect, there is provided a device for implementing multimode fiber amplifier mode self-cleaning, comprising:
the laser beam splitting module is used for receiving the seed light output by the seed laser and splitting the seed light into signal light and auxiliary light for output;
the graded index gain optical fiber amplifier is used for amplifying the signal light and the auxiliary light;
the laser beam splitter is used for splitting and outputting the amplified signal light and auxiliary light;
the laser mode analysis device is used for carrying out optical mode analysis on one beam of signal light and one beam of auxiliary light and outputting various mode information; the method comprises the steps of,
the feedback module is electrically connected with the laser mode analysis device and is used for generating power feedback information according to the mode information and outputting the power feedback information to the laser beam splitting module;
the laser beam splitting module is used for carrying out power proportion adjustment on the power of the signal light and the power of the auxiliary light according to the power feedback information, and the laser beam splitting lens is used for outputting target laser with the power proportion adjusted.
In some embodiments, the laser beam splitting module includes a power beam splitting module, a signal light angle adjusting module, an auxiliary light angle adjusting module, and a first focusing lens;
the power beam splitting module is used for splitting the seed light into signal light and auxiliary light and adjusting the power of the signal light and the power of the auxiliary light;
the signal light included angle adjusting module is used for adjusting the transmission included angle of the signal light;
the auxiliary light included angle power adjusting module is used for adjusting the transmission included angle and power of auxiliary light;
the power beam splitting module is used for transmitting the signal light with the adjusted included angle, the included angle and the auxiliary light with the adjusted power to the first focusing lens, and the first focusing lens transmits the received signal light and the auxiliary light to the graded index gain optical fiber amplifier.
In some embodiments, the power beam splitting module comprises a half-wave plate arranged on one side of the seed laser, a first reflecting mirror arranged on one side of the half-wave plate, and a polarization beam splitting mirror; the first reflector is arranged between the half-wave plate and the polarization beam splitter.
In some embodiments, the signal light included angle adjusting module includes a first quarter wave plate and a second reflecting mirror, which are arranged at one side of the polarization beam splitter, and the first quarter wave plate is arranged between the second reflecting mirror and the polarization beam splitter;
the auxiliary light included angle power adjusting module comprises a second quarter wave plate, an acousto-optic modulator and a third reflector, wherein the second quarter wave plate, the acousto-optic modulator and the third reflector are arranged on one side of the polarization beam splitter, the second quarter wave plate is arranged between the acousto-optic modulator and the polarization beam splitter, and the acousto-optic modulator is arranged between the second quarter wave plate and the third reflector;
the first focusing lens is arranged on the other side of the polarization beam splitter.
In some embodiments, the second mirror is not at an angle of 90 degrees to the transmission path of the signal light; or alternatively, the process may be performed,
the included angle between the third reflecting mirror and the transmission path of the auxiliary light is not 90 degrees.
In some embodiments, the laser pattern analysis device comprises a laser beam shrinking device, a pattern filtering reflector device, a second focusing lens, a first photodetector and a second photodetector;
the laser beam shrinking device is arranged between the laser beam splitter and the mode filtering reflector device and is used for shrinking one beam of signal light and one beam of auxiliary light;
the mode filtering reflector device is arranged between the laser beam shrinking device and the second photoelectric detector and is used for separating out a fundamental mode laser and a high-order mode laser from one of the signal light and one of the auxiliary light after beam shrinking;
the second focusing lens and the first photoelectric detector are arranged on one side of the mode filtering reflector device, the first photoelectric detector is electrically connected with the feedback module, and the first photoelectric detector is used for detecting the high-order mode laser and outputting high-order mode measurement information;
the second photoelectric detector is arranged on the other side of the mode filtering reflector device, and is electrically connected with the feedback module and used for detecting the fundamental mode laser and outputting fundamental mode measurement information.
In some embodiments, the mode filter mirror device comprises two filter mirrors, and each filter mirror is provided with a mode hole, and the aperture of the mode hole is larger than the beam radius of the fundamental mode laser.
In a second aspect, there is provided a system for implementing multimode fiber amplifier mode self-cleaning, comprising:
a seed laser for outputting seed light; the method comprises the steps of,
the device for realizing the mode self-cleaning of the multimode fiber amplifier is arranged on one side of the seed laser.
In a third aspect, a method for implementing mode self-cleaning of a multimode fiber amplifier is provided, comprising the steps of:
the laser beam splitting module receives seed light output by the seed laser and splits the seed light into signal light and auxiliary light for output;
amplifying the signal light and the auxiliary light by a graded index gain optical fiber amplifier;
the laser beam splitter splits and outputs the amplified signal light and auxiliary light;
the laser mode analysis device performs optical mode analysis on one beam of signal light and one beam of auxiliary light and outputs various mode information;
the feedback module generates power feedback information according to the mode information and outputs the power feedback information to the laser beam splitting module;
and the laser beam splitting module adjusts the power ratio of the signal light and the power of the auxiliary light according to the power feedback information, and the laser beam splitting lens outputs the target laser with the adjusted power ratio.
Compared with the prior art, the laser beam splitting module splits the seed light into the signal light and the auxiliary light, and the auxiliary light is used for controlling the dynamic grating; then the signal light and the auxiliary light are simultaneously coupled into a graded index gain fiber amplifier for amplification; the amplified signal light and auxiliary light are split by the laser beam splitter, a small part of the signal light and auxiliary light are reflected to the laser mode analysis device for optical mode analysis, multiple mode information is output, error signals are generated after the signal light and auxiliary light are processed by the feedback device, the laser beam splitter module is controlled in a feedback mode, the power ratio of the signal light and the auxiliary light is adjusted, mode self-cleaning is achieved, and therefore high-beam quality target laser output by the laser beam splitter in a transmission mode is obtained.
Drawings
FIG. 1 is a schematic diagram of a system for implementing multimode fiber amplifier mode self-cleaning in accordance with the present invention;
FIG. 2 is a schematic view of the structure of a laser beam splitting module of the present invention;
FIG. 3 is a schematic diagram of a laser pattern analysis apparatus according to the present invention;
FIG. 4 is a flow chart of an embodiment of a method for implementing a multimode fiber amplifier mode self-cleaning method according to the present invention.
Reference numerals:
100. a seed laser; 200. a laser beam splitting module; 201. a half-wave plate; 202. a first mirror; 203. a polarization beam splitter; 204. a first quarter wave plate; 205. a second mirror; 206. a second quarter wave plate; 207. an acousto-optic modulator; 208. a third mirror; 209. a first focusing lens; 300. a graded index gain fiber amplifier; 400. a laser beam splitter; 500. a laser pattern analysis device; 501. a laser beam shrinking device; 502. a mode filtering mirror device; 503. a second focusing lens; 504. a first photodetector; 505. a second photodetector; 600. and a feedback device.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, an embodiment of the present invention provides a device for implementing a multimode fiber amplifier mode self-cleaning, including:
the laser beam splitting module 200 is configured to receive the seed light output by the seed laser 100, and split the seed light into signal light and auxiliary light for output;
a graded-index gain fiber amplifier 300 for amplifying the signal light and the auxiliary light; the core refractive index of the graded-index gain fiber amplifier 300 increases gradually along the radial direction until the core reaches a maximum;
the laser beam splitter 400 is configured to split and output the amplified signal light and the auxiliary light;
the laser pattern analysis device 500 is configured to perform optical pattern analysis on one of the signal light beams and one of the auxiliary light beams, and output multiple pattern information; the method comprises the steps of,
the feedback module is electrically connected with the laser mode analysis device 500, and is used for generating power feedback information according to the mode information and outputting the power feedback information to the laser beam splitting module 200;
the laser beam splitting module 200 adjusts the power ratio of the signal light and the power of the auxiliary light according to the power feedback information, and the laser beam splitter 400 outputs the target laser with the adjusted power ratio.
Specifically, in this embodiment, the laser beam splitting module 200 splits the seed light into signal light and auxiliary light, where the auxiliary light is used to control the dynamic grating; then the signal light and the auxiliary light are simultaneously coupled into the graded index gain fiber amplifier 300 for amplification; the amplified signal light and auxiliary light are split by the laser beam splitter 400, a small part of the signal light and auxiliary light are reflected to the laser mode analysis device 500 for optical mode analysis, multiple mode information is output, error signals are generated after the processing of the feedback device 600, the laser beam splitter module 200 is controlled in a feedback manner, the power ratio of the signal light and the auxiliary light is adjusted, and mode self-cleaning is realized, so that high-beam quality target laser output by the laser beam splitter 400 in a transmission manner is obtained.
According to the theory of beam transport of graded index fibers, the propagation constant of the fundamental mode exhibits equidistant values, so that the associated mode coupling causes periodic local intensity oscillations along the fiber, which are converted by kerr effect into periodic longitudinal modulation of the refractive index, thus forming a virtual refractive index grating whose distribution and grating period are related to the peak power density in the fiber. Therefore, the auxiliary light is introduced to excite a high-order mode in the laser amplification and transmission process, and the purpose of adjusting the refractive index grating distribution can be realized, so that the self-cleaning of the light beam is realized.
Therefore, the invention controls the peak power of the auxiliary light coupled to the graded index gain fiber amplifier 300, controls the power ratio of the signal light and the auxiliary light, and forms a dynamic mode filter grating by utilizing the graded index fiber beam transmission constant under the effect of the Kerr effect, thereby obtaining the self-cleaning of the beam under any power and improving the output beam quality.
Referring to fig. 2, the laser beam splitting module 200 includes a power beam splitting module, a signal light angle adjusting module, an auxiliary light angle adjusting module, and a first focusing lens 209;
the power beam splitting module is used for splitting the seed light into signal light and auxiliary light and adjusting the power of the signal light and the power of the auxiliary light;
the signal light included angle adjusting module is used for adjusting the transmission included angle of the signal light;
the auxiliary light included angle power adjusting module is used for adjusting the transmission included angle and power of auxiliary light;
the power splitting module is configured to transmit the signal light after the angle adjustment, the auxiliary light after the angle adjustment, and the power adjustment to the first focusing lens 209, and the first focusing lens 209 transmits the received signal light and the auxiliary light to the graded-index gain optical fiber amplifier 300.
Specifically, in this embodiment, the signal light angle adjusting module adjusts the transmission angle of the signal light, and the auxiliary light angle power adjusting module adjusts the transmission angle and power of the auxiliary light; the two output lasers are not coincident or parallel and have a certain included angle, so that the virtual refractive index grating is excited; the angle and peak power of auxiliary light coupled to the multimode graded gain fiber are controlled, the power proportion of signal light and auxiliary light is controlled, and under the effect of Kerr effect, a dynamic mode filter grating is formed by utilizing the graded refractive index fiber beam transmission constant, so that the self-cleaning of the beam is obtained under any power, and the quality of the output beam is improved.
Optionally, the power beam splitting module includes a first half-wave plate 201 disposed on one side of the seed laser 100, a first reflecting mirror 202 disposed on one side of the first half-wave plate 201, and a polarization beam splitter 203; the first reflecting mirror 202 is disposed between the first half-wave plate 201 and the polarization beam splitter 203.
The first half-wave plate 201 can rotate the polarization direction of light, and the polarization beam splitter 203 can select the transmitted polarization direction, and the combination of the two can realize continuous adjustment of the optical power energy.
Optionally, the signal light included angle adjusting module includes a first quarter wave plate 204 and a second reflecting mirror 205 disposed at one side of the polarization beam splitter 203, where the first quarter wave plate 204 is disposed between the second reflecting mirror 205 and the polarization beam splitter 203;
the auxiliary light included angle power adjustment module includes a second quarter wave plate 206, an acousto-optic modulator 207 and a third reflecting mirror 208, which are disposed on one side of the polarization beam splitter 203, the second quarter wave plate 206 is disposed between the acousto-optic modulator 207 and the polarization beam splitter 203, and the acousto-optic modulator 207 is disposed between the second quarter wave plate 206 and the third reflecting mirror 208;
the first focusing lens 209 is disposed on the other side of the polarization beam splitter 203.
Specifically, in this embodiment, after the seed light output by the seed laser 100 passes through the first half-wave plate 201, the polarization state changes, and the seed light is reflected by the first reflecting mirror 202 (45 ° reflecting mirror) on the polarization beam splitter 203, and by adjusting the angle of the first half-wave plate 201, the power primary distribution of the signal light and the auxiliary light can be realized. Then, the split signal light and the auxiliary light, one path of signal light is reflected back to the polarization beam splitter 203 along the original path after passing through the first quarter wave plate 204 and the second mirror 205 (0 ° mirror), and is transmitted into the first focusing lens 209 through the polarization beam splitter 203 due to the polarization rotation effect of the first quarter wave plate 204. The other beam of light, as auxiliary light, passes through the second quarter wave plate 206, the acousto-optic modulator 207, and the third mirror 208 (0 ° mirror), and is transmitted through the polarization beam splitter 203 into the first focusing lens 209 due to the polarization rotation effect of the second quarter wave plate 206. The input light is coupled to the zero-order optical axis of the acousto-optic modulator 207, and the diffraction effect of the acousto-optic modulator 207 can be utilized to realize accurate control of auxiliary optical power, namely, the power value of the zero-order diffraction signal can be adjusted; therefore, the auxiliary light is utilized to excite the high-order mode, the virtual refractive index grating distribution is adjusted, and the mode self-cleaning is realized.
Optionally, the included angle between the second reflecting mirror 205 and the transmission path of the signal light is not 90 degrees; alternatively, the included angle between the third reflecting mirror 208 and the transmission path of the auxiliary light is not 90 degrees.
Specifically, in this embodiment, the 0 ° reflecting mirror and the input beam do not form a 90 ° relationship, and slightly deflect by a small angle, so as to ensure that the auxiliary light or the signal light passes through the first focusing lens 209 and then enters the graded index gain fiber amplifier 300 along different optical axes in a coupling manner, so that the auxiliary light is used to excite a higher-order mode, and the virtual refractive index grating distribution is adjusted, thereby realizing mode self-cleaning. Referring specifically to fig. 3, the laser pattern analysis device 500 includes a laser beam condensing device 501, a pattern filtering mirror device 502, a second focusing lens 503, a first photodetector 504 and a second photodetector 505;
the laser beam shrinking device 501 is arranged between the laser beam splitter 400 and the mode filtering reflector device 502, and is used for shrinking one beam of signal light and one beam of auxiliary light;
the mode filtering mirror device 502 is disposed between the laser beam shrinking device 501 and the second photodetector 505, and is configured to separate a fundamental mode laser beam and a higher-order mode laser beam from one of the signal light beams after beam shrinking and one of the auxiliary light beams;
the second focusing lens 503 and the first photodetector 504 are disposed on one side of the mode filtering mirror device 502, the first photodetector 504 is electrically connected to the feedback module, and the first photodetector 504 is configured to detect the high-order mode laser and output high-order mode measurement information;
the second photodetector 505 is disposed on the other side of the mode filtering mirror device 502, and the second photodetector 505 is electrically connected to the feedback module, and is configured to detect the fundamental mode laser and output fundamental mode measurement information.
Optionally, the mode filtering mirror device 502 includes two filtering mirrors, each of which is provided with a mode hole, where the aperture of the mode hole is larger than the beam radius of the fundamental mode laser.
The two filter mirrors correspond to the signal light and the auxiliary light, respectively, one filter mirror separates the fundamental mode laser and the higher-order mode laser from the signal light, and the other filter mirror separates the fundamental mode laser and the higher-order mode laser from the auxiliary light.
Specifically, in this embodiment, the laser beam shrinking device 501 includes two lenses disposed opposite to each other; the amplified laser is coupled into a laser beam shrinking device 501 by a small part after passing through a laser beam splitter 400 to shrink the beam of the light spot, and then is coupled to a mode filtering reflector device 502; the filtering reflector is a reflector with a small hole in the center of the lens, and the laser close to the fundamental mode is coupled to the second photodetector 505 through the small hole by utilizing the characteristic that the divergence angle of the higher-order mode is larger than that of the fundamental mode, and the higher-order mode with a larger divergence angle is reflected to the second focusing lens 503 to be focused on the first photodetector 504 again. The signals output by the two photodetectors are input to the feedback device 600, and differential operation is performed to obtain a feedback signal, so as to control the acousto-optic modulator 207 to perform dynamic power adjustment.
The embodiment of the invention also provides a system for realizing the mode self-cleaning of the multimode optical fiber amplifier, which comprises the following steps: a seed laser 100 for outputting seed light; and the device for realizing the multimode fiber amplifier mode self-cleaning according to the above is provided at one side of the seed laser 100.
The seed laser 100 is a continuous or pulsed laser, and different lasers may be selected according to application requirements, including but not limited to a mode-locked pulsed fiber laser, a single frequency fiber laser, a continuous fiber laser, etc.
Referring to fig. 4, the embodiment of the invention further provides a method for realizing mode self-cleaning of the multimode optical fiber amplifier, which comprises the following steps:
s100, a laser beam splitting module receives seed light output by a seed laser and splits the seed light into signal light and auxiliary light for output;
s200, amplifying the signal light and the auxiliary light by using a graded index gain optical fiber amplifier;
s300, the laser beam splitter splits and outputs the amplified signal light and auxiliary light;
s400, the laser mode analysis device performs optical mode analysis on one beam of signal light and one beam of auxiliary light, and outputs various mode information;
s500, a feedback module generates power feedback information according to the mode information and outputs the power feedback information to the laser beam splitting module;
and S600, the laser beam splitting module adjusts the power ratio of the signal light and the power of the auxiliary light according to the power feedback information, and the laser beam splitting mirror outputs the target laser with the adjusted power ratio.
Specifically, in this embodiment, after the seed light output by the seed laser passes through the half-wave plate, the polarization state changes, and the seed light is reflected on the polarization beam splitter by the first reflector, and by adjusting the angle of the half-wave plate, the power preliminary distribution of the signal light and the auxiliary light can be realized. And then, after the signal light and the auxiliary light are split, one path of signal light is reflected back to the polarization beam splitter along the original path after passing through the first quarter wave plate and the second reflecting mirror (0 DEG reflecting mirror), and is transmitted to the first focusing lens through the polarization beam splitter due to the polarization rotation effect of the first quarter wave plate. The other beam of light is taken as auxiliary light, passes through a second quarter wave plate, an acousto-optic modulator and a third reflector (0 DEG reflector), and then is transmitted to the first focusing lens through a polarization beam splitter due to the polarization rotation effect of the second quarter wave plate. The input light is coupled to the zero-order optical axis of the acousto-optic modulator, and the diffraction effect of the acousto-optic modulator can be utilized to realize accurate control of auxiliary light power, namely the power value of a zero-order diffraction signal can be adjusted; the 0-degree reflecting mirror and the input light beam do not form 90 degrees, and slightly deflect a small angle, so that auxiliary light or signal light is guaranteed to be coupled into the graded index gain optical fiber amplifier along different optical axes after passing through the first focusing lens, and amplified laser is slightly coupled into the laser beam shrinking device for shrinking light spots after passing through the laser beam splitting mirror and then coupled into the mode filtering reflecting mirror device; the filtering reflector is a reflector with a small hole in the center of the lens, and laser close to the fundamental mode is coupled to the second photoelectric detector through the small hole by utilizing the characteristic that the divergence angle of the high-order mode is larger than that of the fundamental mode, and the high-order mode with larger divergence angle is reflected to the second focusing lens to be focused on the first photoelectric detector again. The signals output by the two photoelectric detectors are input into a feedback device to perform differential operation to obtain feedback signals, so that the acousto-optic modulator is controlled to perform dynamic power adjustment.
Therefore, the invention controls the peak power of the auxiliary light coupled to the graded index gain optical fiber amplifier, controls the power proportion of the signal light and the auxiliary light, and forms a dynamic mode filter grating by utilizing the graded index optical fiber beam transmission constant under the effect of the Kerr effect, thereby obtaining the self-cleaning of the light beam under any power and improving the output light beam quality.
In the description of the present invention, it should be noted that the azimuth or positional relationship indicated by the terms "upper", "lower", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of describing the present invention and simplifying the description, and are not indicative or implying that the apparatus or element in question must have a specific azimuth, be constructed and operated in a specific azimuth, and thus should not be construed as limiting the present invention. Unless specifically stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
It should be noted that in the present invention, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, 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. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing is only a specific embodiment of the invention to enable those skilled in the art to understand or practice the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. A device for implementing multimode fiber amplifier mode self-cleaning, comprising:
the laser beam splitting module is used for receiving the seed light output by the seed laser and splitting the seed light into signal light and auxiliary light for output;
the graded index gain optical fiber amplifier is used for amplifying the signal light and the auxiliary light;
the laser beam splitter is used for splitting and outputting the amplified signal light and auxiliary light;
the laser mode analysis device is used for carrying out optical mode analysis on one beam of signal light and one beam of auxiliary light and outputting various mode information; the method comprises the steps of,
the feedback module is electrically connected with the laser mode analysis device and is used for generating power feedback information according to the mode information and outputting the power feedback information to the laser beam splitting module;
the laser beam splitting module is used for carrying out power proportion adjustment on the power of the signal light and the power of the auxiliary light according to the power feedback information, and the laser beam splitting lens is used for outputting target laser with the power proportion adjusted.
2. The device for realizing the mode self-cleaning of the multimode optical fiber amplifier according to claim 1, wherein the laser beam splitting module comprises a power beam splitting module, a signal light included angle adjusting module, an auxiliary light included angle adjusting module and a first focusing lens;
the power beam splitting module is used for splitting the seed light into signal light and auxiliary light and adjusting the power of the signal light and the power of the auxiliary light;
the signal light included angle adjusting module is used for adjusting the transmission included angle of the signal light;
the auxiliary light included angle power adjusting module is used for adjusting the transmission included angle and power of auxiliary light;
the power beam splitting module is used for transmitting the signal light with the adjusted included angle, the included angle and the auxiliary light with the adjusted power to the first focusing lens, and the first focusing lens transmits the received signal light and the auxiliary light to the graded index gain optical fiber amplifier.
3. The device for realizing the mode self-cleaning of the multimode fiber amplifier according to claim 2, wherein the power beam splitting module comprises a half-wave plate arranged on one side of the seed laser, a first reflecting mirror arranged on one side of the half-wave plate, and a polarization beam splitting mirror; the first reflector is arranged between the half-wave plate and the polarization beam splitter.
4. The device for realizing the mode self-cleaning of the multimode optical fiber amplifier according to claim 3, wherein the signal light included angle adjusting module comprises a first quarter wave plate and a second reflecting mirror which are arranged on one side of the polarization beam splitter, and the first quarter wave plate is arranged between the second reflecting mirror and the polarization beam splitter;
the auxiliary light included angle power adjusting module comprises a second quarter wave plate, an acousto-optic modulator and a third reflector, wherein the second quarter wave plate, the acousto-optic modulator and the third reflector are arranged on one side of the polarization beam splitter, the second quarter wave plate is arranged between the acousto-optic modulator and the polarization beam splitter, and the acousto-optic modulator is arranged between the second quarter wave plate and the third reflector;
the first focusing lens is arranged on the other side of the polarization beam splitter.
5. The device of claim 4, wherein an included angle between the second reflecting mirror and a transmission path of the signal light is not 90 degrees; or alternatively, the process may be performed,
the included angle between the third reflecting mirror and the transmission path of the auxiliary light is not 90 degrees.
6. The apparatus of any one of claims 1 to 5, wherein the laser pattern analysis apparatus comprises a laser beam condensing apparatus, a pattern filtering mirror apparatus, a second focusing lens, a first photodetector, and a second photodetector;
the laser beam shrinking device is arranged between the laser beam splitter and the mode filtering reflector device and is used for shrinking one beam of signal light and one beam of auxiliary light;
the mode filtering reflector device is arranged between the laser beam shrinking device and the second photoelectric detector and is used for separating out a fundamental mode laser and a high-order mode laser from one of the signal light and one of the auxiliary light after beam shrinking;
the second focusing lens and the first photoelectric detector are arranged on one side of the mode filtering reflector device, the first photoelectric detector is electrically connected with the feedback module, and the first photoelectric detector is used for detecting the high-order mode laser and outputting high-order mode measurement information;
the second photoelectric detector is arranged on the other side of the mode filtering reflector device, and is electrically connected with the feedback module and used for detecting the fundamental mode laser and outputting fundamental mode measurement information.
7. The device of claim 6, wherein the mode filter mirror device comprises two filter mirrors, each filter mirror is provided with a mode hole, and the aperture of the mode hole is larger than the beam radius of the fundamental mode laser.
8. A system for implementing multimode fiber amplifier mode self-cleaning, comprising:
a seed laser for outputting seed light; the method comprises the steps of,
the device for realizing multimode fiber amplifier mode self-cleaning according to any one of claims 1 to 7, which is provided at one side of the seed laser.
9. The method for realizing the mode self-cleaning of the multimode optical fiber amplifier is characterized by comprising the following steps of:
the laser beam splitting module receives seed light output by the seed laser and splits the seed light into signal light and auxiliary light for output;
amplifying the signal light and the auxiliary light by a graded index gain optical fiber amplifier;
the laser beam splitter splits and outputs the amplified signal light and auxiliary light;
the laser mode analysis device performs optical mode analysis on one beam of signal light and one beam of auxiliary light and outputs various mode information;
the feedback module generates power feedback information according to the mode information and outputs the power feedback information to the laser beam splitting module;
and the laser beam splitting module adjusts the power ratio of the signal light and the power of the auxiliary light according to the power feedback information, and the laser beam splitting lens outputs the target laser with the adjusted power ratio.
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