CN110165530B - High-power Raman fiber laser generation method and system - Google Patents

High-power Raman fiber laser generation method and system Download PDF

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CN110165530B
CN110165530B CN201910550599.9A CN201910550599A CN110165530B CN 110165530 B CN110165530 B CN 110165530B CN 201910550599 A CN201910550599 A CN 201910550599A CN 110165530 B CN110165530 B CN 110165530B
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raman
laser
fiber
order
lambda
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CN110165530A (en
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马鹏飞
来文昌
刘伟
宋家鑫
王涛
姜曼
姚天甫
粟荣涛
吴坚
马阎星
周朴
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National University of Defense Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • H01S3/06716—Fibre compositions or doping with active elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • H01S3/06725—Fibre characterized by a specific dispersion, e.g. for pulse shaping in soliton lasers or for dispersion compensating [DCF]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06754—Fibre amplifiers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094042—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser
    • H01S3/094046—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser of a Raman fibre laser
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H01S3/30—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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  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

The invention provides a high-power Raman fiber laser generation method and a system, which are used for stabilizing the time domain with the central wavelength lambda 0 The single-frequency fiber laser or the multi-single-frequency fiber laser is used as 1-order Raman pump light. The system comprises a 1-order Raman pump photon system and a Raman fiber laser, wherein the 1-order Raman pump photon system is used for generating a time domain stable center wavelength lambda 0 The single-frequency fiber laser or the multi-single-frequency fiber laser is used as 1-order Raman pump light, the 1-order Raman pump light pumps the Raman fiber laser, and wavelength conversion and power amplification from the 1-order Raman pump light to the k-order Raman laser are realized. The invention utilizes the influence of the Raman pump light time domain stability on the Raman conversion efficiency, the high-order Raman generation threshold and the output laser spectrum purity, effectively improves the comprehensive performance of the high-power Raman fiber laser system from the aspect of the Raman pump light generation mode, and provides an effective technical scheme for the fiber light source design in the fields of nonlinear frequency conversion, gas detection, atmospheric optics, self-adaptive optics and the like.

Description

High-power Raman fiber laser generation method and system
Technical Field
The invention belongs to the technical field of strong laser and nonlinear fiber optics, and particularly relates to a novel method for generating high-power Raman fiber laser.
Background
Compared with other types of lasers, the fiber laser has the advantages of high conversion efficiency, good beam quality, convenient thermal management, compact structure, flexible operation, simple maintenance and the like, and has wide application prospect in the fields of laser processing, material forming, laser welding, laser cleaning and the like.
At present, the physical mechanisms for generating high-power fiber laser are mainly divided into two types:
(1) The rare earth ion doped is directly adopted to provide amplification gain, so that high-power fiber laser output is realized; in the method, rare earth ions can be selected from ytterbium ions, erbium-ytterbium co-doped ions, thulium ions, holmium ions and the like according to different excitation wavelengths.
(2) And the nonlinear mechanism is utilized to provide amplification gain, so that high-power fiber laser output is realized. The method mainly relies on the nonlinear action processes of stimulated Raman scattering, stimulated Brillouin scattering, distributed Rayleigh scattering, nonlinear parameter conversion and the like to effectively realize wavelength conversion and power amplification of output laser. The fiber lasers/amplifiers implemented based on the different nonlinear effect mechanisms are respectively called raman fiber laser oscillators/amplifiers, brillouin fiber lasers/amplifiers, random fiber lasers/amplifiers, optical parametric oscillators/amplifiers, and the like in the academy. The raman fiber laser oscillator/amplifier is a main technical means for realizing high-power fiber laser output, and is widely focused by researchers at home and abroad due to the characteristics of low loss, large die area, long interaction length and the like of the fiber. In addition, the optical fiber for providing the Raman gain does not need to be doped with rare earth ions, so that the limitation of the rare earth ion laser spectrum on the central wavelength of the output laser is avoided, and the Raman fiber laser oscillator/amplifier has the special advantages of ultra-wide band amplification, flexible and tunable wavelength and the like. In addition, the raman fiber laser oscillator/amplifier is not limited by the space hole burning effect of the reversed particle number when realizing high power output due to the limitation of no doped ions. The high power boosting potential, the ultra-wide band amplifying capability and the flexible and tunable wavelength property enable the Raman fiber laser oscillator/amplifier to have special application requirements in the fields of nonlinear frequency conversion, gas detection, atmospheric optics, self-adaptive optics and the like.
In raman fiber laser oscillators/amplifiers, in order to increase conversion efficiency, reduce amplification threshold and provide sufficient amplification gain, it is generally necessary to provide raman gain using an optical fiber having a smaller core and the length of the optical fiber is generally in the order of hundreds of meters or more. Thus, spectral broadening and higher order raman can severely impact the system's development toward high power, high spectral purity. In order to overcome the above problems, researchers have proposed methods of suppressing the generation of higher order raman by using special filtering optical fibers, novel multi-clad optical fibers, and the like. However, most of the existing high-order Raman suppression methods depend on novel optical fiber designs, and are difficult to realize and high in cost. In addition, the high-power Raman fiber laser generation method comprehensively considering conversion efficiency improvement, spectrum purity optimization and high-order Raman suppression is still very deficient. Therefore, comprehensively considering the defects, the novel effective technical means for realizing the high-power Raman fiber laser is provided, and the novel effective technical means have important scientific significance and practical needs.
Disclosure of Invention
Aiming at the defects in the technical field of the existing strong laser and nonlinear fiber optics, the invention provides a high-power Raman fiber laser generation method and system.
The invention utilizes the influence of the Raman pump light time domain stability on the Raman conversion efficiency, the high-order Raman generation threshold and the output laser spectrum purity, effectively improves the comprehensive performance of the high-power Raman fiber laser system from the aspect of the Raman pump light generation mode, and provides an effective technical scheme for the fiber light source design in the fields of nonlinear frequency conversion, gas detection, atmospheric optics, self-adaptive optics and the like.
In order to achieve the technical purpose, the technical scheme of the invention is as follows:
a high-power Raman fiber laser generation method is characterized in that: the time domain stable center wavelength is lambda 0 Single frequency light of (2)The fiber laser or the multi-single-frequency fiber laser is used as 1-order Raman pump light. Wherein time domain stabilization refers to the absence of self-mode locking pulses, relaxation oscillation pulses, and turbulence-like pulses in the 1 st order raman pump light. The specific method comprises the following steps:
1-order Raman pump optical pumping Raman gain fiber with center wavelength lambda 0 Is converted into the 1 st order Raman pump light with the central wavelength lambda 1 1 st order raman laser of (2); the amplified center wavelength is lambda 1 Is used as the 1 st order Raman laser with the central wavelength lambda 2 Is a pumping light of 2-order Raman laser with a central wavelength lambda 1 Is lambda from 1 st order Raman laser to center wavelength 2 Raman amplification and wavelength conversion of 2-order raman laser light; and so on, the amplified center wavelength is lambda k-1 The k-1 order raman laser of (2) acts as a laser with a center wavelength lambda k Pumping light of K-order Raman laser of (1) realizing central wavelength lambda k-1 Is directed to the center wavelength lambda by the K-1 order Raman laser k Raman amplification and wavelength conversion of a k-order raman laser of (2) such that a wavelength lambda from the center is achieved 0 Is 1-order Raman pump light with central wavelength lambda k Raman amplification and wavelength conversion of a k-order raman laser of (2) to ultimately produce a center wavelength λ k A k-th order raman laser of (2); wherein the wavelength lambda i Satisfy the relation lambda i ＝λ i-1 And +Deltalambda, 1 is less than or equal to i is less than or equal to k, and Deltalambda is the frequency shift of the Raman Stokes light corresponding to the Raman gain fiber matrix material in the wavelength domain. The method provided by the invention is based on a time domain stable pumping technology to realize the improvement of Raman conversion efficiency, high-order Raman suppression and the optimization of Raman amplification spectral purity.
In the raman amplification process, if the 1-order raman pump light is generated by a semiconductor laser, an optical fiber oscillator or a super-fluorescent optical fiber light source, time domain noise of the pump light is transmitted to the corresponding raman amplified laser, so that raman conversion efficiency is reduced, a high-order raman generation threshold is reduced, and laser spectrum purity is degraded. Specifically, the center wavelength is λ 0 Time domain noise in the 1 st order raman pump light of (2) is transferred to the center wavelength lambda 1 1-order Raman laser of (2), center wavelength is lambda 1 1 st order raman laser of (2)Time domain noise is transferred to the center wavelength lambda 2 2-order raman laser of (2), and so on, with a center wavelength of lambda k-1 The k-1 order Raman laser time domain noise of (2) is transmitted to the center wavelength lambda k Is finally caused to lambda by the k-order raman laser of (2) k The conversion efficiency of the k-order Raman laser of (2) is reduced, further power boost is limited by high-order Raman, and the output laser spectrum is seriously widened and the spectrum purity is degraded.
In order to avoid the defects, the invention adopts a time domain stable pumping technology, namely adopts time domain stable 1-order Raman pumping light, can effectively inhibit noise transmission in a high-power Raman amplification system, effectively inhibits high-order Raman, and further improves Raman conversion efficiency, a high-order Raman generation threshold value and output laser spectrum purity.
Compared with a semiconductor laser, a fiber oscillator or a super-fluorescent fiber light source, the noise level of the single-frequency fiber laser can reach the quantum noise limit, and the time domain noise of the multi-single-frequency laser generated by the single-frequency fiber laser through phase modulation or the multi-single-frequency laser generated by the combination of a plurality of different-wavelength single-frequency fiber lasers is lower, so that the single-frequency fiber laser is an ideal light source for pumping a high-power Raman fiber laser system. Generally, the raman gain spectrum can cover tens of terahertz, so that the wavelength coverage of multiple single-frequency lasers is less than-30 nm in the near infrared, communication band, mid-infrared and far-infrared ranges of >1 um.
A high-power Raman fiber laser generation system comprises a 1-order Raman pump photon system and a Raman fiber laser, wherein the 1-order Raman pump photon system is used for generating a time domain stable center wavelength lambda 0 The single-frequency fiber laser or the multi-single-frequency fiber laser is used as 1-order Raman pump light, the 1-order Raman pump light pumps the Raman fiber laser, and wavelength conversion and Raman amplification from the 1-order Raman pump light to the k-order Raman laser are realized.
The 1-order Raman pump photon system comprises a 1-order Raman pump light seed source, an all-fiber beam splitter and a 1-order Raman pump light amplification array; 1 st order Raman pump light seed source for generating time domain stable center wavelength lambda 0 Single-frequency fiber laser or multi-single-frequency fiber laser; all-fiber beam splitterDividing laser emitted by a seed source into r sub-lasers; the r-stage sub-laser is subjected to power amplification by the 1-stage Raman pump light amplification array, and the laser pumping Raman fiber laser output by the amplification of the 1-stage Raman pump light amplification array.
The 1-order Raman pump light amplifying array comprises r all-fiber amplifier modules which are respectively used for amplifying the power of r sub-lasers.
As the preferable technical scheme of the invention, the invention further comprises a cladding light filter, the laser output by the Raman fiber laser is injected into the cladding light filter, the cladding light in the output laser is filtered to free space, and the influence of the cladding light on the quality of the light beam is avoided. Further, the system also comprises an optical fiber collimator, and the optical fiber laser after passing through the cladding light filter passes through the optical fiber collimator and is output to a free space.
The test system for measuring the time domain characteristics, the spectral characteristics and the beam quality parameters of the high-power Raman fiber laser generation system comprises the high-power Raman fiber laser generation system, a dichroic mirror, a residual light receiver, a high-reflection mirror, a power meter and a time-space-frequency integrated real-time measurement system, wherein the time-space-frequency integrated real-time measurement system comprises a photoelectric detection display instrument, a spectral measuring instrument and a beam quality analyzer. The laser output by the fiber collimator in the high-power Raman fiber laser generating system is firstly incident to the dichroic mirror, the dichroic mirror filters residual laser which is not completely converted in amplified laser to a residual light receiver, and the Raman amplified laser output by reflection of the dichroic mirror is further reflected to the power meter by the high-reflection mirror. And the light beam transmitted by the high-reflection mirror is injected into a space-time frequency integrated real-time measurement system to realize the test of time domain characteristics, spectral characteristics and light beam quality parameters.
The key for realizing the improvement of the Raman conversion efficiency, the high-order Raman suppression and the optimization of the output laser spectrum purity in the invention is as follows: the 1-order Raman pump light seed source is single-frequency optical fiber laser with stable time domain or multi-single-frequency laser generated by phase modulation of single-frequency optical fiber laser with stable time domain or multi-single-frequency laser generated by combining multiple single-frequency optical fiber lasers with different wavelengths with stable time domain. Generally, the raman gain spectrum can cover tens of terahertz, so that the wavelength coverage of multiple single-frequency lasers is less than-30 nm in the near infrared, communication band, mid-infrared and far-infrared ranges of >1 um. Wherein: the implementation structure of the time domain stable single-frequency fiber laser can be a distributed Bragg reflection type single-frequency fiber laser, a distributed feedback type single-frequency fiber laser, a ring cavity single-frequency fiber laser and the like. If the 1-order raman pump light seed source is multi-single-frequency laser generated by phase modulation of single-frequency fiber laser with stable time domain, a phase modulation device is generally externally connected to the single-frequency fiber laser with stable time domain, and an electrical modulation signal is applied to the phase modulation device to realize multi-single-frequency laser output. The phase modulation device is typically an electro-optic modulator, which may be a lithium niobate material, a graphene material, or other material that enables electro-optic modulation. The phase modulation signal may be sinusoidal, white noise, rectangular pulse, triangular pulse, hyperbolic secant pulse, pseudo-random phase code, etc., or any combination or concatenation of the above different modulation signals.
In the invention, the all-fiber beam splitter divides the laser output by the 1-order Raman pump light seed source into r-path sub-lasers, and the beam splitting ratio of the all-fiber beam splitter is generally 1: r is not limited to the method of manufacturing, and may be a melt tapering method or a diaphragm method.
In the invention, the 1-order Raman pump light amplifying array comprises r all-fiber amplifier modules, the number of the stages is not limited, and the 1-order Raman pump light amplifying array can be a single-stage all-fiber amplifier or a multistage cascade all-fiber amplifier. Center wavelength lambda of 1-order Raman pump light 0 In the all-fiber amplifier module, the wavelength range can be amplified.
In the invention, the Raman fiber laser can be a Raman fiber laser oscillator or a Raman fiber laser amplifier.
When the Raman fiber laser adopts a Raman fiber laser oscillator, the Raman fiber laser oscillator comprises a 1-order Raman pump beam combiner, a Raman gain fiber and fiber grating pair combinations matched with different orders of Raman light, the 1-order Raman pump light is a high-reflection grating, and laser amplified by a 1-order Raman pump light amplifying array is injected into the 1-order Raman pump beam combinerRealize beam combination, and the center wavelength led out by a 1-order Raman pump beam combiner is lambda 0 1-order Raman pump light of (1) is injected into a Raman gain fiber, and the combination of fiber bragg grating pairs matched with different-order Raman light realizes that the center wavelength is lambda through a k-order Raman amplification process 0 Is 1-order Raman pump light with central wavelength lambda k Wavelength conversion and amplification of a k-order raman laser of (2), wherein the different order raman light-matched fiber gratings comprise k pairs of gratings having a center wavelength λ k The center wavelength of the k-1 pair grating is lambda k-1 By analogy, the center wavelength of the 1 st pair of gratings is lambda 1 . Except that the kth pair of gratings consists of a central wavelength lambda k And a high reflection grating with a center wavelength lambda k The other grating pairs are composed of a pair of high-reflectivity gratings, namely the k-1 grating pair is composed of a pair of gratings with central wavelength lambda k-1 Is composed of a pair of high-reflection gratings whose central wavelength is lambda k-2 Is … … the 1 st pair of gratings consists of a pair of gratings with center wavelength lambda 1 Is composed of high reflective grating. The oscillation and amplification are realized in the oscillation cavity formed by the 1 st pair of gratings, and the center wavelength is lambda 0 Is converted into the 1 st order Raman pump light with the central wavelength lambda 1 1 st order raman laser of (2); the amplified center wavelength is lambda 1 Is used as the 1 st order Raman laser with the central wavelength lambda 2 Pumping light pumping Raman gain fiber of 2-order Raman laser of (2) pair of gratings realizes oscillation and amplification in an oscillation cavity formed by the 2 nd pair of gratings, and realizes that the center wavelength is lambda 1 Is lambda from 1 st order Raman laser to center wavelength 2 Raman amplification and conversion of 2-order raman laser; and so on, the amplified center wavelength is lambda k-1 The k-1 order raman laser of (2) acts as a laser with a center wavelength lambda k Pumping light pumping Raman gain fiber of k-order Raman laser of (2) realizes oscillation and amplification in an oscillation cavity formed by a k-th pair of gratings, and realizes that the center wavelength is lambda k-1 Is directed to the center wavelength lambda by the K-1 order Raman laser k Raman amplification and conversion of a k-th order raman laser of (c); since the k pair of gratings consists of a central wavelength lambda k And a high reflection grating with a center wavelength lambda k Is formed by low reflection grating, and finally passes through Raman fiberThe amplified center wavelength of the laser oscillator is lambda k Will pass through the kth grating and its low-reflection grating output. The 1-order Raman pump light is secondarily reflected to the Raman gain fiber by the 1-order Raman pump light high-reflection grating, so that a secondary pumping effect is realized, the effective length of the Raman gain fiber is effectively reduced, and the utilization rate of the 1-order Raman pump light is improved. Finally, the wavelength conversion and Raman amplification from the 1 st order Raman pump light to the k th order Raman laser light are realized.
When the Raman fiber laser adopts the Raman fiber laser amplifier, the Raman fiber laser amplifier realizes that the center wavelength is lambda through k-order Raman amplification and conversion 0 Is 1-order Raman pump light with central wavelength lambda k Wavelength conversion and amplification of the k-th order raman laser of (c). The Raman fiber laser amplifier comprises a 1-order Raman pump-signal beam combiner, a Raman gain fiber and a Raman fiber laser seed, wherein laser amplified and output by the 1-order Raman pump light amplification array is injected into the Raman gain fiber through a pumping arm of the 1-order Raman pump-signal beam combiner to be used as an initial pumping light pumping Raman gain fiber for Raman amplification. The Raman fiber laser seed contains a center wavelength lambda 1 、λ 2 …λ k A multi-wavelength fiber laser of spectral composition. Wherein: lambda (lambda) i (1. Ltoreq.i.ltoreq.k) satisfies the relation lambda i ＝λ i-1 +Deltalambda, deltalambda is the amount of shift in the wavelength domain of the Raman Stokes light corresponding to the Raman gain fiber matrix material. The Raman fiber laser seeds are injected into the Raman gain fiber through a signal arm of a 1-order Raman pump-signal beam combiner to serve as Raman amplified servo seed signals. The laser output by the Raman fiber laser seed is pumped by 1-order Raman pump light, and the Raman gain fiber provides gain to make the center wavelength lambda 0 Is converted into the 1 st order Raman pump light with the central wavelength lambda 1 1 st order raman amplified laser of (2); the amplified center wavelength is lambda 1 Is used as the 1 st order Raman laser with the central wavelength lambda 2 Pumping the Raman gain fiber under the servo of the Raman fiber laser seeds to realize the central wavelength lambda of the pumping light of the 2-order Raman laser 1 Is lambda from 1 st order Raman laser to center wavelength 2 Raman amplification and conversion of 2-order raman laser; analogize to the same, center after amplificationWavelength lambda k-1 The k-1 order raman laser of (2) acts as a laser with a center wavelength lambda k Pumping the Raman gain fiber under the servo of the Raman fiber laser seeds to realize the central wavelength lambda of the pumping light of the K-order Raman laser k-1 Is directed to the center wavelength lambda by the K-1 order Raman laser k Is provided for amplifying and converting the k-order Raman laser. Finally, the wavelength conversion and Raman amplification from the 1 st order Raman pump light to the k th order Raman laser light are realized.
According to the invention, the cladding light filter filters the cladding light generated by Raman amplification into free space, so that the degradation of the quality and the spectral purity of the Raman amplified laser beam caused by the cladding light is prevented.
In the invention, the optical fiber collimator realizes the collimation emission of amplified laser, can effectively reduce the laser power density of the output end face and protects the safety of the amplifier. The optical fiber collimator can be realized by one or a plurality of lens combinations, the materials of the lens are various, and the optical fiber collimator can be fused quartz, znSe and CaF 2 Etc.
In the invention, the dichroic mirror is used for filtering the center wavelength lambda which is not completely converted after Raman amplification 0 、λ 1 、λ 2 …λ k-1 Is a laser beam with a center wavelength lambda k The Raman amplified laser of (2) is spatially separated, and the constituent materials are not limited, and may be fused silica, K 9 、ZnSe、CaF 2 Etc.
In the invention, the residual light receiver is used for receiving the light with the center wavelength lambda which is not completely converted after Raman amplification 0 、λ 1 、λ 2 …λ k-1 The laser beam can be a cone-shaped residual light receiver made of quartz material, a cone-shaped residual light receiver made of copper material, etc., or can be a traditional power meter, etc.
In the invention, the high-reflection mirror has a center wavelength lambda k The Raman amplified laser of (2) is reflected to the power meter, and the constituent materials are not limited and can be fused quartz or K 9 And the like, specifically selected according to the irradiation laser power density, the reflection spectrum of which includes the output spectrum of the raman amplified laser.
In the invention, the power meter is used for receivingAnd measuring a center wavelength lambda k The output power of the raman amplified laser.
In the invention, the space-time frequency integrated real-time measurement system consists of a photoelectric detection display instrument, a spectrum measuring instrument and a light beam quality analyzer. The photoelectric detection display instrument is generally composed of a photoelectric detector and an oscilloscope or the photoelectric detector and a frequency spectrograph and is used for observing the time domain stability and the intensity noise of the Raman amplified laser; the spectrum measuring instrument is used for measuring the spectrum distribution of the Raman amplified laser; the beam quality analyzer is used for observing and measuring the beam quality and far-field spot morphology of the Raman amplified laser.
Compared with the prior art, the invention can produce the following technical effects:
1. the invention provides a technical scheme for improving Raman conversion efficiency, a high-order Raman threshold and beam purity by adopting a single-frequency laser or multi-single-frequency laser pumping high-power Raman fiber laser oscillator with stable time domain based on the influence of the time domain stability of 1-order Raman pump light on the conversion efficiency, the high-order Raman generation threshold and the spectrum purity of the high-power Raman fiber laser oscillator.
The 1-order Raman pump light seed source is injected into a Raman fiber laser oscillator after beam splitting and power amplification, the fiber bragg grating pairs matched with different orders of Raman light in the Raman fiber laser oscillator realize round trip oscillation and amplification of different orders of Raman laser, the 1-order Raman pump light high reflection grating realizes reflection of initial pump light, the 1-order Raman pump light is reflected to a Raman gain fiber to realize secondary pumping effect, and finally wavelength conversion and power amplification from the 1-order Raman pump light to the k-order Raman laser are realized.
2. The invention provides a technical scheme for improving Raman conversion efficiency, a high-order Raman threshold and light beam purity by adopting a single-frequency laser or multi-single-frequency laser pumping high-power Raman fiber laser amplifier with stable time domain based on the influence of the time domain stability of 1-order Raman pump light on the conversion efficiency, the high-order Raman generation threshold and the light beam purity of the high-power Raman fiber laser amplifier.
In the scheme, a 1-order Raman pump light seed source is injected into a Raman fiber laser amplifier after beam splitting and power amplification, the Raman fiber laser seed provides a servo seed signal for Raman gain amplification, and finally wavelength conversion and power amplification from 1-order Raman pump light to k-order Raman laser are realized. The key of the scheme is as follows: the 1-order Raman pump light seed source is (1) single-frequency optical fiber laser with stable time domain or (2) multi-single-frequency laser generated by phase modulation of single-frequency optical fiber laser with stable time domain or (3) multi-single-frequency laser generated by combining a plurality of single-frequency optical fiber lasers with different wavelengths with stable time domain. Generally, the raman gain spectrum can cover tens of terahertz, so that the wavelength coverage of multiple single-frequency lasers is less than-30 nm in the near infrared, communication band, mid-infrared and far-infrared ranges of >1 um.
3. In the invention, the generation modes of the 1-order Raman pump light seed source are various, and the time domain stable single-frequency fiber laser realization structure can be a distributed Bragg reflection type single-frequency fiber laser, a distributed feedback type single-frequency fiber laser, an annular cavity single-frequency fiber laser and the like; if the 1-order raman pump light seed source is multi-single-frequency laser generated by phase modulation of single-frequency fiber laser with stable time domain, a phase modulation device is generally externally connected to the single-frequency fiber laser with stable time domain, and an electrical modulation signal is applied to the phase modulation device to realize multi-single-frequency laser output. The phase modulation device is typically an electro-optic modulator, which may be a lithium niobate material, a graphene material, or other material that enables electro-optic modulation. The phase modulation signal may be sinusoidal, white noise, rectangular pulse, triangular pulse, hyperbolic secant pulse, pseudo-random phase code, etc., or any combination or concatenation of the above different modulation signals.
4. In the invention, the Raman fiber laser seeds have various realization modes and can contain the center wavelength lambda 1 、λ 2 …λ k The output multi-wavelength fiber laser or amplifier can also be a fiber laser with the center wavelength of lambda 1 、λ 2 …λ k The multi-wavelength fiber laser generated by the beam combination of the k fiber lasers or the amplifiers.
5. In the present invention, the matrix material of the raman gain fiber may be selected from a hard glass matrix material (e.g., silica), a soft glass mechanism material (e.g., silicate, phosphate, etc.), and other types of matrix materials.
6. The invention has universality: for the amplifying wavelength range, the central wavelength lambda of the 1 st order Raman pump light is determined by selection 0 And matrix materials of the Raman gain fiber, the method can be used for wavelength conversion and amplification of fiber lasers covering near infrared wave bands and communication wave bands, and can also be used for wavelength conversion and amplification of fiber lasers in middle infrared wave bands or other wave bands. In terms of the polarization characteristics of the amplified laser, the method can be used for wavelength conversion and amplification of linearly polarized fiber laser and also can be used for wavelength conversion and amplification of randomly polarized fiber laser.
Drawings
Fig. 1 is a schematic structural diagram of the general technical scheme of the present invention.
Fig. 2 is a schematic structural diagram of embodiment 1 of the present invention.
Fig. 3 is a schematic structural diagram of embodiment 2 of the present invention.
Detailed Description
Embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
Fig. 1 is a schematic structural diagram of the general technical scheme of the invention, as shown in fig. 1, and comprises a 1-order raman pump light seed source 1, an all-fiber beam splitter 2, a 1-order raman pump light amplification array 3, a raman fiber laser 4, a cladding light filter 5, an optical fiber collimator 6, a dichroic mirror 7, a residual light receiver 8, a high-reflection mirror 9, a power meter 10 and a time-frequency integrated real-time measurement system 11. The high-power Raman fiber laser generation system is composed of a 1-order Raman pump light seed source 1, an all-fiber beam splitter 2, a 1-order Raman pump light amplification array 3, a Raman fiber laser 4, a cladding light filter 5 and a fiber collimator 6. The high-power Raman fiber laser generation system, the dichroic mirror 7, the residual light receiver 8, the high-reflection mirror 9, the power meter 10 and the space-time integrated real-time measurement system 11 form a test system for measuring the time domain characteristics, the spectral characteristics and the beam quality parameters of the high-power Raman fiber laser generation system.
Wherein: the 1-order Raman pump light amplifying array 3 comprises r all-fiber amplifier modules 3-1 and 3-2 … -r. The space-time frequency integrated real-time measurement system 11 comprises a photoelectric detection display 11-1, a spectrum measuring instrument 11-2 and a light beam quality analyzer 11-3.
The 1-order Raman pump light seed source 1 can be single-frequency optical fiber laser with stable time domain or multi-single-frequency laser generated by phase modulation of single-frequency optical fiber laser with stable time domain or multi-single-frequency laser generated by combining multiple single-frequency optical fiber lasers with different wavelengths with stable time domain. Generally, the raman gain spectrum can cover tens of terahertz, so that the wavelength coverage of multiple single-frequency lasers is less than-30 nm in the near infrared, communication band, mid-infrared and far-infrared ranges of >1 um. The time domain stable single-frequency optical fiber laser realizing structure can be a distributed Bragg reflection type single-frequency optical fiber laser, a distributed feedback type single-frequency optical fiber laser, an annular cavity single-frequency optical fiber laser and the like; if the 1 st order raman pump light seed source 1 is multi-single-frequency laser generated by phase modulation of single-frequency fiber laser with stable time domain, the multi-single-frequency laser output is generally realized by externally connecting a phase modulation device to the single-frequency fiber laser with stable time domain and applying an electrical modulation signal to the phase modulation device. The phase modulation device is typically an electro-optic modulator, which may be a lithium niobate material, a graphene material, or other material that enables electro-optic modulation. The phase modulation signal may be sinusoidal, white noise, rectangular pulse, triangular pulse, hyperbolic secant pulse, pseudo-random phase code, etc., or any combination or concatenation of the above different modulation signals.
The 1 st order Raman pump light seed source 1 outputs a stable central wavelength lambda in time domain 0 The single-frequency fiber laser or the multi-single-frequency fiber laser is divided into r sub-lasers after passing through the all-fiber beam splitter 2, and the divided r sub-lasers are incident to the 1-order Raman pump light amplifying array 3. The 1-order Raman pump light amplifying array comprises r all-fiber amplifier modules 3-1 and 3-2 … -r which are respectively used for amplifying r sub-lasers in power.
Defining 1-order Raman pump light center wavelength as lambda 0 The 1 st order Raman laser has a central wavelength lambda 1 By analogy, k-order Raman laser central waveLambda of length k . Wherein the wavelength lambda i (1. Ltoreq.i.ltoreq.k) satisfies the relation lambda i ＝λ i-1 +Deltalambda, deltalambda is the amount of shift in the wavelength domain of the Raman Stokes light corresponding to the Raman gain fiber matrix material.
The laser amplified and output by the 1-order Raman pump light amplifying array 3 is injected into the Raman fiber laser 4, and initial pump light is provided for the Raman fiber laser 4, namely the stable center wavelength is lambda 0 1 st order raman pump light of (c). The Raman fiber laser 4 realizes the central wavelength lambda through the k-order Raman amplification process 0 Is 1-order Raman pump light with central wavelength lambda k Wavelength conversion and amplification of the k-th order raman laser of (c). Specifically, the 1 st order raman pump light first pumps the raman fiber laser 4 to a center wavelength λ 0 Is converted into the 1 st order Raman pump light with the central wavelength lambda 1 1 st order raman laser of (2); the amplified center wavelength is lambda 1 Is used as the 1 st order Raman laser with the central wavelength lambda 2 Pumping light pumping Raman fiber laser 4 of 2-order Raman laser of (2) to realize central wavelength lambda 1 Is lambda from 1 st order Raman laser to center wavelength 2 Raman amplification and wavelength conversion of 2-order raman laser light; and so on, the amplified center wavelength is lambda k-1 The k-1 order raman laser of (2) acts as a laser with a center wavelength lambda k Pumping light pumping Raman fiber laser 4 of K-order Raman laser of (2) realizing center wavelength lambda k-1 Is directed to the center wavelength lambda by the K-1 order Raman laser k Raman amplification and wavelength conversion of a k-th order raman laser of (c); finally realize lambda from the central wavelength 0 Is 1-order Raman pump light with central wavelength lambda k Wavelength conversion and raman amplification of the k-th order raman laser of (c). The laser light amplified by the raman fiber laser 4 is injected into the cladding light filter 5. The cladding light filter 5 filters the cladding light in the Raman amplified laser to a free space, so that the influence of the cladding light on the quality of the light beam is avoided; the raman laser after passing through the cladding light filter 5 passes through the optical fiber collimator 6 and then is output to the free space. The laser light output from the fiber collimator 6 is first incident on the dichroic mirror 7, and the dichroic mirror 7 amplifies the laser light with a center wavelength lambda which is not completely converted 0 、λ 1 、λ 2 …λ k-1 The residual laser light of (2) is filtered out to a residual light receiver 8, and the raman amplified laser light output by reflection of the dichroic mirror 7 is further reflected to a power meter 10 by a high reflection mirror 9. The light beam transmitted by the high-reflection mirror 9 is injected into the time-frequency integrated real-time measurement system 11. The time-space frequency integrated real-time measurement system 11 consists of a photoelectric detection display 11-1, a spectrum measuring instrument 11-2 and a beam quality analyzer 11-3, and respectively tests and characterizes the time domain characteristics, the spectrum characteristics and the beam quality parameters of output laser.
A specific embodiment of an aspect of the present invention will be described in further detail with reference to fig. 2. The raman fiber laser in fig. 2 employs a raman fiber laser oscillator.
Fig. 2 is a schematic structural diagram of embodiment 1 of the present invention, as shown in fig. 2, including a 1 st order raman pump light seed source 1, an all-fiber beam splitter 2, a 1 st order raman pump light amplifying array 3, a raman fiber laser oscillator 2-4, a cladding light filter 5, a fiber collimator 6, a dichroic mirror 7, a residual light receiver 8, a high-reflection mirror 9, a power meter 10, and a time-frequency integrated real-time measurement system 11. Wherein: the 1-order Raman pump light amplifying array 3 comprises m all-fiber amplifier modules 3-1, 2-3-2 … -m; the Raman fiber laser oscillator 2-4 comprises a 1-order Raman pump beam combiner 2-4-1, a Raman gain fiber 2-4-2, and a fiber grating pair combination 2-4-3 matched with different orders of Raman light, wherein the 1-order Raman pump light high-reflection grating 2-4. The space-time frequency integrated real-time measurement system 11 comprises a photoelectric detection display 11-1, a spectrum measuring instrument 11-2 and a light beam quality analyzer 11-3.
In the combination 2-4-3 of the fiber grating pairs matched with the Raman light of different orders, the fiber grating pair matched with the Raman light of the kth order is (2-4-3-2 k, 2-4-3-1), the fiber grating pair matched with the Raman light of the kth-1 order is (2-4-3-2 k-1, 2-4-3-2), and the fiber grating pair matched with the Raman light of the 1 st order is (2-4-3-k+1, 2-4-3-k) in turn.
The 1-order Raman pump light seed source 1 can be single-frequency optical fiber laser with stable time domain or multi-single-frequency laser generated by phase modulation of single-frequency optical fiber laser with stable time domain or multi-single-frequency laser generated by combining a plurality of single-frequency optical fiber lasers with different wavelengths with stable time domain. Generally, the raman gain spectrum can cover tens of terahertz, so that the wavelength coverage of multiple single-frequency lasers is less than-30 nm in the near infrared, communication band, mid-infrared and far-infrared ranges of >1 um. The time domain stable single-frequency optical fiber laser realizing structure can be a distributed Bragg reflection type single-frequency optical fiber laser, a distributed feedback type single-frequency optical fiber laser, an annular cavity single-frequency optical fiber laser and the like; if the 1 st order raman pump light seed source 1 is multi-single-frequency laser generated by phase modulation of single-frequency fiber laser with stable time domain, the multi-single-frequency laser output is generally realized by externally connecting a phase modulation device to the single-frequency fiber laser with stable time domain and applying an electrical modulation signal to the phase modulation device. The phase modulation device is typically an electro-optic modulator, which may be a lithium niobate material, a graphene material, or other material that enables electro-optic modulation. The phase modulation signal may be sinusoidal, white noise, rectangular pulse, triangular pulse, hyperbolic secant pulse, pseudo-random phase code, etc., or any combination or concatenation of the above different modulation signals.
The 1-order Raman pump light seed source 1 is firstly divided into m sub-lasers after passing through the all-fiber beam splitter 2, and the m sub-lasers after being split are incident to the 1-order Raman pump light amplifying array 3. The 1-order Raman pump light amplifying array comprises m all-fiber amplifier modules 3-1 and 3-2 … -m which are respectively used for amplifying the power of m-path laser. The Raman fiber laser oscillator 2-4 comprises a 1-order Raman pump beam combiner 2-4-1, a Raman gain fiber 2-4-2, fiber grating pair combinations 2-4-3 matched with different orders of Raman light, and a 1-order Raman pump high-reflection grating 2-4. The laser amplified by the 1-order Raman pump light amplifying array 3 is injected into the Raman gain fiber 2-4-2 through the 1-order Raman pump beam combiner 2-4-1 to be used as an initial pumping light pumping Raman amplifying process of Raman amplification. The fiber bragg grating pair combination 2-4-3 matched with the Raman light of different orders realizes the round trip oscillation and amplification of the Raman laser of different orders, and the specific process is as follows: defining 1-order Raman pump light center wavelength as lambda 0 The 1 st order Raman laser has a central wavelength lambda 1 By analogy, the center wavelength of the k-order Raman laser is lambda k . Wherein,wavelength lambda i (1. Ltoreq.i.ltoreq.k) satisfies the relation lambda i ＝λ i-1 +Deltalambda, deltalambda is the amount of shift in the wavelength domain of the Raman Stokes light corresponding to the Raman gain fiber matrix material. Setting the central wavelength of the Raman fiber laser oscillator 2-4 as lambda through the k-order Raman amplification process 0 Is 1-order Raman pump light with central wavelength lambda k The combination of the fiber grating pairs matched with the Raman light of different orders comprises k pairs of gratings in 2-4-3. In FIG. 2, the k-th grating (2-4 to 3-2 k,2-4 to 3-1) has a center wavelength of lambda k The center wavelength of the k-1 pair grating (2-4-3-2 k-1, 2-4-3-2) is lambda k-1 By analogy, the center wavelength of the 1 st pair of gratings (2-4 to 3-k+1, 2-4 to 3-k) is lambda 1 . Wherein the kth pair of gratings (2-4-3-2 k, 2-4-3-1) has a center wavelength lambda k High reflection grating 2-4-3-2 k and a center wavelength lambda k Is composed of low-reflection gratings 2-4-3-1, the k-1 pair of gratings (2-4-3-2 k-1, 2-4-3-2), k-2 pair of gratings (2-4-3-2 k-2, 2-4-3) … … the 1 st pair of gratings (2-4-3-k+1, 2-4-3-k) are respectively corresponding to the central wavelength lambda k-1 、λ k-2 ……λ 1 Is a high reflection grating of (2). The center wavelength derived by the 1-order Raman pump beam combiner 2-4-1 is lambda 0 The 1-order Raman pump light of (1) is firstly pumped to the Raman gain optical fiber 2-4-2, the oscillation and amplification are realized in an oscillation cavity formed by the 1 st pair of gratings (2-4-3-k+1, 2-4-3-k), and the center wavelength is lambda 0 Is converted into the 1 st order Raman pump light with the central wavelength lambda 1 1 st order raman laser of (2); the amplified center wavelength is lambda 1 Is used as the 1 st order Raman laser with the central wavelength lambda 2 The pumping light pumping Raman gain fiber 2-4-2 of the 2 nd-order Raman laser realizes oscillation and amplification in an oscillation cavity formed by the 2 nd pair of gratings (2-4-3-k+2, 2-4-3-k-1) and realizes the central wavelength lambda 1 Is lambda from 1 st order Raman laser to center wavelength 2 Raman amplification and conversion of 2-order raman laser; and so on, the amplified center wavelength is lambda k-1 The k-1 order raman laser of (2) acts as a laser with a center wavelength lambda k Pumping light pumping Raman gain fiber 2-4-2 of k-order Raman laserThe oscillation and amplification are realized in an oscillation cavity formed by the kth grating (2-4 to 3-2 k,2-4 to 3-1), and the central wavelength is lambda k-1 Is directed to the center wavelength lambda by the K-1 order Raman laser k Raman amplification and conversion of a k-th order raman laser of (c); since the k-th grating (2-4-3-2 k, 2-4-3-1) has a center wavelength lambda k High reflection grating 2-4-3-2 k and a center wavelength lambda k Is composed of low reflection gratings 2-4 to 3-1, so that the central wavelength finally amplified by the Raman fiber laser oscillator is lambda k The laser of (2) is output through the low reflection grating 2-4-3-1. The 1-order Raman pump light is secondarily reflected to the Raman gain optical fiber 2-4-2 by the 1-order Raman pump light high-reflection grating 2-4, so that a secondary pumping effect is realized, the effective length of the Raman gain optical fiber is effectively reduced, and the utilization rate of the 1-order Raman pump light is improved. Finally, the wavelength conversion and Raman amplification from the 1 st order Raman pump light to the k th order Raman laser light are realized. The laser amplified by the Raman fiber laser oscillator 2-4 is injected into the cladding light filter 5. The cladding light filter 5 filters the cladding light in the Raman amplified laser to a free space, so that the influence of the cladding light on the quality of the light beam is avoided; the raman laser after passing through the cladding light filter 5 passes through the optical fiber collimator 6 and then is output to the free space. The laser light output from the fiber collimator 6 is first incident on the dichroic mirror 7, and the dichroic mirror 7 amplifies the laser light with a center wavelength lambda which is not completely converted 0 、λ 1 、λ 2 …λ k-1 The residual laser light of (2) is filtered out to a residual light receiver 8, and the raman amplified laser light output by reflection of the dichroic mirror 7 is further reflected to a power meter 10 by a high reflection mirror 9. The light beam transmitted by the high-reflection mirror 9 is injected into the time-frequency integrated real-time measurement system 11. The time-space frequency integrated real-time measurement system 11 consists of a photoelectric detection display 11-1, a spectrum measuring instrument 11-2 and a beam quality analyzer 11-3, and respectively tests and characterizes the time domain characteristics, the spectrum characteristics and the beam quality parameters of output laser.
A second embodiment of the present invention will be described in further detail with reference to fig. 3. In this embodiment, the raman fiber laser uses a raman fiber laser amplifier.
Fig. 3 is a schematic diagram of a system structure according to a second embodiment of the present invention, as shown in fig. 3, including a 1 st order raman pump light seed source 1, an all-fiber beam splitter 2, a 1 st order raman pump light amplification array 3, a raman fiber laser amplifier 3-4, a cladding light filter 5, a fiber collimator 6, a dichroic mirror 7, a residual light receiver 8, a high-reflection mirror 9, a power meter 10, and a time-frequency integrated real-time measurement system 11.
Wherein:
the 1-order Raman pump light amplifying array 3 comprises n all-fiber amplifier modules 3-1, 3-2 … -n; the Raman fiber laser amplifier 3-4 comprises a 1-order Raman pump-signal beam combiner 3-4-1, a Raman gain fiber 3-4-2 and a Raman fiber laser seed 3-4-3; the space-time frequency integrated real-time measurement system 11 comprises a photoelectric detection display 11-1, a spectrum measuring instrument 11-2 and a light beam quality analyzer 11-3.
The 1-order Raman pump light seed source 1 can be single-frequency optical fiber laser with stable time domain or multi-single-frequency laser generated by phase modulation of single-frequency optical fiber laser with stable time domain or multi-single-frequency laser generated by combining a plurality of single-frequency optical fiber lasers with different wavelengths with stable time domain. Generally, the raman gain spectrum can cover tens of terahertz, so that the wavelength coverage of multiple single-frequency lasers is less than-30 nm in the near infrared, communication band, mid-infrared and far-infrared ranges of >1 um. The time domain stable single-frequency optical fiber laser realizing structure can be a distributed Bragg reflection type single-frequency optical fiber laser, a distributed feedback type single-frequency optical fiber laser, an annular cavity single-frequency optical fiber laser and the like; if the 1 st order raman pump light seed source 1 is multi-single-frequency laser generated by phase modulation of single-frequency fiber laser with stable time domain, the multi-single-frequency laser output is generally realized by externally connecting a phase modulation device to the single-frequency fiber laser with stable time domain and applying an electrical modulation signal to the phase modulation device. The phase modulation device is typically an electro-optic modulator, which may be a lithium niobate material, a graphene material, or other material that enables electro-optic modulation. The phase modulation signal may be sinusoidal, white noise, rectangular pulse, triangular pulse, hyperbolic secant pulse, pseudo-random phase code, etc., or any combination or concatenation of the above different modulation signals.
The 1-order Raman pump light seed source 1 is firstly divided into n sub-lasers after passing through the all-fiber beam splitter 2, and the n sub-lasers after being split are incident to the 1-order Raman pump light amplifying array 3. The 1-order Raman pump light amplifying array comprises n all-fiber amplifier modules 3-1, 3-2 …, 3-n-1 and 3-n which are respectively used for amplifying the power of n paths of 1-order Raman pump photon lasers. The Raman fiber laser amplifier 3-4 is composed of a 1-order Raman pump-signal beam combiner 3-4-1, a Raman gain fiber 3-4-2 and a Raman fiber laser seed 3-4-3. The laser amplified by the 1-order Raman pump light amplifying array 3 is injected into the Raman gain fiber 3-4-2 through the pumping arm of the 1-order Raman pump-signal beam combiner 3-4-1 to be used as the initial pumping light for Raman amplification to pump the Raman gain fiber 3-4-2. Wherein, the 1-order Raman pump-signal beam combiner 3-4-1 is an all-fiber pump-signal beam combiner of (n×1) +1. If the Raman fiber laser amplifier 3-4 realizes the center wavelength lambda through the k-order Raman amplification and conversion 0 Is 1-order Raman pump light with central wavelength lambda k The laser seeds 3-4-3 of the Raman fiber are the laser seeds containing the center wavelength lambda after the wavelength conversion and amplification of the K-order Raman laser 1 、λ 2 …λ k A multi-wavelength fiber laser of spectral composition. Wherein: lambda (lambda) i (1. Ltoreq.i.ltoreq.k) satisfies the relation lambda i ＝λ i-1 +Deltalambda, deltalambda is the amount of shift in the wavelength domain of the Raman Stokes light corresponding to the Raman gain fiber matrix material. The Raman fiber laser seeds 3-4-3 are injected into the Raman gain fiber 3-4-2 through a signal arm of a 1-order Raman pump-signal beam combiner 3-4-1 to serve as Raman amplified servo seed signals. The laser output by the Raman fiber laser seeds 3-4-3 is pumped by 1-order Raman pump light, and the center wavelength is lambda by providing gain through the Raman gain fibers 3-4-2 0 Is converted into the 1 st order Raman pump light with the central wavelength lambda 1 1 st order raman amplified laser of (2); the amplified center wavelength is lambda 1 Is used as the 1 st order Raman laser with the central wavelength lambda 2 Pumping the 2-order Raman laser pump light of the Raman gain fiber 3-4-2 under the servo of the Raman fiber laser seeds 3-4-3 to realize the central wavelength lambda 1 Is lambda from 1 st order Raman laser to center wavelength 2 Raman amplification and of 2-order raman laser of (2)Conversion; and so on, the amplified center wavelength is lambda k-1 The k-1 order raman laser of (2) acts as a laser with a center wavelength lambda k Pumping light of K-order Raman laser of (3-4-2) is pumped under the servo of Raman fiber laser seeds 3-4-3 to realize the central wavelength of lambda k-1 Is directed to the center wavelength lambda by the K-1 order Raman laser k Is provided for amplifying and converting the k-order Raman laser. The whole physical process can be understood as a process of performing raman amplification while converting in the raman fiber laser amplifier 3-4, and finally realizing wavelength conversion and power amplification from the 1 st order raman pump light to the k th order raman laser light. The laser amplified by the raman fiber laser amplifier 3-4 is injected into the cladding light filter 5. The cladding light filter 5 filters the cladding light in the output laser to a free space, so that the influence of the cladding light on the quality of the output laser beam is avoided; the raman laser after passing through the cladding light filter 5 passes through the optical fiber collimator 6 and then is output to the free space. The laser light output from the fiber collimator 6 is first incident on the dichroic mirror 7, and the dichroic mirror 7 amplifies the laser light with a center wavelength lambda which is not completely converted 0 、λ 1 、λ 2 …λ k-1 The residual laser light of (2) is filtered out to a residual light receiver 8, and the raman amplified laser light output by reflection of the dichroic mirror 7 is further reflected to a power meter 10 by a high reflection mirror 9. The light beam transmitted by the high-reflection mirror 9 is injected into the time-frequency integrated real-time measurement system 11. The time-space frequency integrated real-time measurement system 11 consists of a photoelectric detection display 11-1, a spectrum measuring instrument 11-2 and a beam quality analyzer 11-3, and respectively tests and characterizes the time domain characteristics, the spectrum characteristics and the beam quality parameters of output laser.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A high-power Raman fiber laser generation system is characterized in that: comprising a 1-order Raman pump photon system and a Raman fiberLaser, 1-order raman pump photon system for generating time domain stable center wavelength lambda 0 The single-frequency fiber laser or the multi-single-frequency fiber laser is used as 1-order Raman pump light, the 1-order Raman pump light pumps the Raman fiber laser, and wavelength conversion and Raman amplification from the 1-order Raman pump light to the k-order Raman laser are realized;
the Raman fiber laser is a Raman fiber laser oscillator or a Raman fiber laser amplifier;
the Raman fiber laser oscillator comprises a 1-order Raman pump beam combiner, a Raman gain fiber, a fiber grating pair combination matched with different orders of Raman light and a 1-order Raman pump light high-reflection grating; the laser amplified and output by the 1-order Raman pump light amplifying array is injected into the 1-order Raman pump beam combiner to realize beam combination, and the center wavelength led out by the 1-order Raman pump beam combiner is lambda 0 1-order Raman pump light of (1) is injected into a Raman gain fiber, and the combination of fiber bragg grating pairs matched with different-order Raman light realizes that the center wavelength is lambda through a k-order Raman amplification process 0 Is 1-order Raman pump light with central wavelength lambda k Wavelength conversion and amplification of a k-th order raman laser of (2); wherein the fiber gratings matched with the Raman light of different orders comprise k pairs of gratings, and the center wavelength of the k pairs of gratings is lambda k The center wavelength of the k-1 pair grating is lambda k-1 By analogy, the center wavelength of the 1 st pair of gratings is lambda 1 The method comprises the steps of carrying out a first treatment on the surface of the The kth pair of gratings consists of a grating with a center wavelength lambda k And a high reflection grating with a center wavelength lambda k The other grating pairs are composed of a pair of high-reflectivity gratings, namely the k-1 grating pair is composed of a pair of gratings with central wavelength lambda k-1 Is composed of a pair of high-reflection gratings whose central wavelength is lambda k-2 Is … … the 1 st pair of gratings consists of a pair of gratings with center wavelength lambda 1 Is composed of high reflective grating; the oscillation and amplification are realized in the oscillation cavity formed by the 1 st pair of gratings, and the center wavelength is lambda 0 Is converted into the 1 st order Raman pump light with the central wavelength lambda 1 1 st order raman laser of (2); the amplified center wavelength is lambda 1 Is used as the 1 st order Raman laser with the central wavelength lambda 2 Pumping light pumping Raman gain fiber of 2-order Raman laser in the following steps The oscillation and amplification are realized in the oscillation cavity formed by the 2 nd pair of gratings, and the central wavelength lambda is realized 1 Is lambda from 1 st order Raman laser to center wavelength 2 Raman amplification and conversion of 2-order raman laser; and so on, the amplified center wavelength is lambda k-1 The k-1 order raman laser of (2) acts as a laser with a center wavelength lambda k Pumping light pumping Raman gain fiber of k-order Raman laser of (2) realizes oscillation and amplification in an oscillation cavity formed by a k-th pair of gratings, and realizes that the center wavelength is lambda k-1 Is directed to the center wavelength lambda by the K-1 order Raman laser k Raman amplification and conversion of k-order raman laser of (2) with a center wavelength lambda k The k-th order raman laser of (c) will pass through the k-th pair of gratings with low light-reflecting grating output.
2. The high power raman fiber laser generating system according to claim 1, wherein: the 1-order Raman pump photon system comprises a 1-order Raman pump light seed source, an all-fiber beam splitter and a 1-order Raman pump light amplification array; 1 st order Raman pump light seed source for generating time domain stable center wavelength lambda 0 Single-frequency fiber laser or multi-single-frequency fiber laser; the all-fiber beam splitter divides the laser emitted by the seed source into r sub-lasers; the r-stage sub-laser is subjected to power amplification by the 1-stage Raman pump light amplification array, and the laser pumping Raman fiber laser output by the amplification of the 1-stage Raman pump light amplification array.
3. The high power raman fiber laser generating system according to claim 1, wherein: the laser beam output by the Raman fiber laser is injected into the cladding light filter, cladding light in the output laser is filtered to a free space, and the fiber laser beam after passing through the cladding light filter is output to the free space after passing through the fiber collimator.
4. The high power raman fiber laser generating system according to claim 2, wherein: the 1-order Raman pump light seed source is single-frequency optical fiber laser with stable time domain or multi-single-frequency laser generated by phase modulation of single-frequency optical fiber laser with stable time domain or multi-single-frequency laser generated by combining multiple single-frequency optical fiber lasers with different wavelengths with stable time domain.
5. The high power raman fiber laser generating system according to claim 1, wherein: the Raman fiber laser is a Raman fiber laser amplifier;
the Raman fiber laser amplifier comprises a 1-order Raman pump-signal beam combiner, a Raman gain fiber and a Raman fiber laser seed;
the laser amplified and output by the 1-order Raman pump light amplifying array is injected into the Raman gain fiber through a pumping arm of the 1-order Raman pump-signal beam combiner to be used as a 1-order Raman pump light pumping Raman gain fiber for Raman amplification; the Raman fiber laser seed contains a center wavelength lambda 1 、λ 2 …λ k A multi-wavelength fiber laser of spectral composition, wherein: lambda (lambda) i Satisfy the relation lambda i ＝λ i-1 +Deltalambda, 1 is less than or equal to i is less than or equal to k, deltalambda is the frequency shift of the Raman Stokes light corresponding to the Raman gain fiber matrix material in the wavelength domain;
the Raman fiber laser seeds are injected into the Raman gain fiber through a signal arm of a 1-order Raman pump-signal beam combiner to serve as Raman amplified servo seed signals; the laser output by the Raman fiber laser seed is pumped by 1-order Raman pump light, and the Raman gain fiber provides gain to make the center wavelength lambda 0 Is converted into the 1 st order Raman pump light with the central wavelength lambda 1 1 st order raman amplified laser of (2); the amplified center wavelength is lambda 1 Is used as the 1 st order Raman laser with the central wavelength lambda 2 Pumping the Raman gain fiber under the servo of the Raman fiber laser seeds to realize the central wavelength lambda of the pumping light of the 2-order Raman laser 1 Is lambda from 1 st order Raman laser to center wavelength 2 Raman amplification and conversion of 2-order raman laser; and so on, the amplified center wavelength is lambda k-1 The k-1 order raman laser of (2) acts as a laser with a center wavelength lambda k Pumping the Raman gain fiber under the servo of the Raman fiber laser seeds to realize the central wavelength lambda of the pumping light of the K-order Raman laser k-1 Is directed to the central wave by the K-1 order Raman laser of (2)Lambda of length k Amplifying and converting the k-order Raman laser of (2), and finally outputting the central wavelength lambda k Is a k-th order raman laser of (c).
6. The high power raman fiber laser generating system according to any one of claims 1 to 5, wherein: also includes a test device for testing the output center wavelength lambda k The test system of the k-order Raman laser of the (4) has time domain characteristics, spectral characteristics and beam quality parameters.
7. The high power raman fiber laser generating system according to claim 6, wherein: the testing system comprises a dichroic mirror, a residual light receiver, a high-reflection mirror, a power meter and a time-frequency integrated real-time measuring system, wherein the time-frequency integrated real-time measuring system comprises a photoelectric detection display instrument, a spectrum measuring instrument and a light beam quality analyzer.
8. The high power raman fiber laser generating system according to claim 7, wherein: the center wavelength is lambda k The k-order Raman laser of (2) is firstly incident into a dichroic mirror, the dichroic mirror filters residual laser which is not converted in full wavelength in amplified laser to a residual light receiver, the Raman amplified laser which is output by reflection of the dichroic mirror is further reflected to a power meter by a high-reflection mirror, and a light beam transmitted by the high-reflection mirror is injected into a time-frequency integrated real-time measurement system to realize the test of time characteristics, spectral characteristics and light beam quality parameters.
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