CN208522239U - System for realizing high-brightness narrow-linewidth ytterbium-doped optical fiber laser amplification - Google Patents
System for realizing high-brightness narrow-linewidth ytterbium-doped optical fiber laser amplification Download PDFInfo
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- CN208522239U CN208522239U CN201820812720.1U CN201820812720U CN208522239U CN 208522239 U CN208522239 U CN 208522239U CN 201820812720 U CN201820812720 U CN 201820812720U CN 208522239 U CN208522239 U CN 208522239U
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Abstract
The utility model provides a realize that high brightness narrow linewidth mixes ytterbium fiber laser enlargies system, this system is synthesized and is compromise the suppression of TMI effect and SBS effect among the high brightness narrow linewidth mixes ytterbium fiber laser amplifier, the threshold value that the SBS effect takes place is judged to the light monitoring arm that utilizes high power coupler, through signal acquisition treater with light signal conversion for voltage signal, and servo the optimization algorithm controller of giving, provide corresponding control signal, and then apply to the radio frequency source in the radio frequency signal generator, the adjustable electrical amplifier of gain, the adjustable electrical band pass filter of bandwidth, realize spectral characteristic's optimization, realize the best suppression effect of SBS effect under the circumstances of guaranteeing that the output linewidth is as narrow as far as possible. Meanwhile, quantum loss of the ytterbium-doped main amplifier is effectively reduced by using a 1018nm pumping source, and efficient suppression of TMI is realized. The utility model discloses a fields such as beam synthesis, nonlinear wavelength conversion, laser communication, coherent radar, remote sensing survey provide the fiber optic source design of higher luminance.
Description
Technical field
The utility model belongs to High-power Laser Technologies field, swashs more particularly to a kind of realization high brightness narrow linewidth Yb dosed optical fiber
The system of light amplification.
Background technique
High brightness narrow linewidth Yb dosed optical fiber laser light beam synthesis, non-linear wavelength convert, laser communication, coherent radar,
The fields such as remote sensing have strong application demand.
Currently, master oscillation power amplification structure (MOPA) is to realize the mainstream of high brightness narrow linewidth Yb dosed optical fiber laser amplifier
Technological means.MOPA structure generally comprises a master oscillator and multi-stage cascade fiber amplifier.Since optical-fiber laser output is bright
Degree is proportional to output power, is inversely proportional to square of beam quality (M2), therefore the main body of luminance raising of optical fiber laser amplifier
Two aspects of present beam quality optimization (scheme control) and power ascension.
However, with the continuous promotion of output power, the thermotropic mode that is generated in narrow linewidth Yb dosed optical fiber laser amplifier
Unstable effect (TMI) and non-linear stimulated Brillouin scattering effect (SBS), which become, limits the main of its further luminance raising
Technical bottleneck.Specifically, being directed to TMI, after output power reaches certain threshold power, optical fiber laser amplifier output mode
There is the Dynamic Coupling from basic mode to higher order mode, cause the distribution of laser output time-domain and frequency domain distribution to occur obvious unstable,
Along with the abrupt degradation of beam quality, the luminance raising ability of narrow linewidth Yb dosed optical fiber laser is seriously limited.For SBS,
After output power reaches certain threshold power, the output power of optical fiber laser amplifier will be quickly to reversed stokes light
Transfer, further promotion pump power will lead to output power for fibre amplifier and stagflation occurs or instead drop, reversed stokes light
There is nonlinear exponent to increase, influence the power ascension and safety of fiber amplifier, it is limited to eventually lead to luminance raising.
Up to now, researchers at home and abroad have carried out system research for above two limited resource respectively, and mention
Corresponding suppressing method is gone out.However, result of study shows that TMI suppressing method and SBS suppressing method have inherent lance at present
Shield, in terms of being embodied in following four:
(1) with the increase of fiber amplifier core size, SBS threshold rises, TMI threshold value reduces；
(2) when pump power deviates 976nm, in the case where guaranteeing fiber amplifier pump absorption efficiency, under SBS threshold
Drop, TMI threshold value rise；
(3) when increasing seed power, SBS threshold is reduced, and TMI threshold value increases；
(4) when introducing modal loss in fiber amplifier, SBS threshold is reduced, TMI threshold value rises.
Common restrict of above two limited resource swashs narrow linewidth Yb dosed optical fiber with the inner contradictions of suppressing method
The luminance raising of image intensifer is extremely difficult.Therefore, comprehensive to take into account the inhibition of SBS and TMI effect, from system design set about proposing into
There is new departure that one step promotes the laser amplifier brightness of narrow linewidth Yb dosed optical fiber important scientific meaning and urgent reality to need
It wants.
Utility model content
In view of the defects existing in the prior art, the purpose of the utility model is to provide a kind of realization high brightness narrow linewidths to mix ytterbium
The system of optical-fiber laser amplification.The utility model synthesis takes into account TMI effect in high brightness narrow linewidth Yb dosed optical fiber laser amplifier
With the inhibition of SBS effect, mentioned for fields such as light beam synthesis, non-linear wavelength convert, laser communication, coherent radar, remote sensings
For the optical fiber source design scheme of more high brightness, push high-power narrow line width optical-fiber laser overall development and application field into
One step is expanded.
To realize the above-mentioned technical purpose, the technical solution of the utility model is:
A kind of system for realizing high brightness narrow linewidth Yb dosed optical fiber laser amplifier, including single frequency optical fiber laser seed source,
Phase-modulator, Yb dosed optical fiber laser preamplifier system, high-power coupler, mixes ytterbium main amplifier, light at rf signal generator
Fine end cap, collimator, high reflective mirror I, high reflective mirror II, power meter, photodetector, beam splitter, optical spectrum instrumentation, beam quality are surveyed
Measure instrument, signal acquisition process device.
The output end tail optical fiber of single frequency optical fiber laser seed source is connected to phase-modulator.Rf signal generator drives phase
Position modulator, the line width of single frequency optical fiber laser seed source is broadened.Broadening of spectral lines directly results in effective brillouin gain spectrum
Broadening, brillouin gain are greatly lowered, and realize effective inhibition of SBS effect.
Laser after phase-modulator is first poured into Yb dosed optical fiber laser preamplifier system and carries out power pre-amplification.
Light beam after Yb dosed optical fiber laser preamplifier system pre-amplification is from a portion after the input of the input arm of high-power coupler
Light beam is exported from the output arm of high-power coupler, and rest part light beam is exported from the light echo of high-power coupler monitoring arm, from
Light beam derived from the output arm of high-power coupler, which is injected into, to be mixed ytterbium main amplifier and carries out final high power amplification.From high power
The light beam of the light echo monitoring arm output of coupler is injected into signal acquisition process device, and signal acquisition process device and radiofrequency signal generate
Device connection；The optical signal of input is converted to electric signal by signal acquisition process device, and generates optimal control according to the variation of electric signal
Signal processed generates optimal phase modulated signal for driving phase-modulation to rf signal generator, by rf signal generator
Device realizes system closed loop.
Laser after mixing ytterbium main amplifier power amplification is output to collimator through end caps, and collimator expands standard
Directly it is output to free space.The laser for collimating output is successively injected into power meter after high reflective mirror I and high reflective mirror II reflection.Through height
The light beam of anti-mirror I transmission is received by a photoelectric detector, and photodetector converts optical signals to electric signal.According to photodetector
The electric signal of output can be used to observe the time domain and frequency domain for exporting laser when generating TMI or SBS effect in fiber amplifier
Variation, judges the threshold value of TMI and SBS according to this.Specifically, when SBS effect occurs in MOPA system, time domain on photodetector
The very high giant-pulse of peak value can occur in continuous substrate in signal；When TMI occurs in MOPA system, time domain is believed on photodetector
It number will appear unstable, show as the unexpected overstriking of time-domain signal.If to time-domain signal progress Fourier transformation, near 2kHz
Apparent characteristic envelope or characteristic peak to occur.
The laser transmitted through high reflective mirror II is divided into two beams after beam splitter, wherein the light beam gone out through beam splitter reflection injects
Optical spectrum instrumentation is realized to the test of output laser spectrum distribution and line width, is incident on light beam through the light beam that beam splitter transmits
Mass measurer, for observing and monitoring the beam quality variation of output laser during whole system power ascension.
In the utility model: rf signal generator is by radio frequency source, adjustable gain electrical amplifier, bandwidth is adjustable electricity band
Bandpass filter is constituted.Broadening of spectral lines directly results in effective brillouin gain spectrum widening, and brillouin gain is greatly lowered, and realizes
Effective inhibition of SBS effect.
Signal acquisition process device is made of photoelectric converter with the controller for being loaded with optimization algorithm.From high-power coupler
Light echo monitoring arm output light beam be injected into photoelectric converter, photoelectric converter converts optical signals to electric signal, and watches
It takes and gives optimization algorithm controller.When non-linear stimulated Brillouin scattering effect (SBS) occurs, from the light echo of high-power coupler
The laser power of monitoring arm output will show exponential increase trend and time domain representation is giant-pulse state.Therefore photoelectric converter
The voltage signal of output will appear apparent non-linear growth trend and unstable, the anomalous variation of photoelectric converter output signal
It can be used as the evaluation function of optimization algorithm controller.
The controller for being loaded with optimization algorithm executes optimization algorithm output optimization based on the electric signal that photoelectric converter exports
Control signal afterwards, control signal include time domain waveform control signal, gain voltage control signal and the control of bandwidth adjustment voltage
Signal, each control signal is applied separately to radio frequency source in rf signal generator, adjustable gain electrical amplifier, bandwidth can
Adjust electricity bandpass filter.Corresponding phase-modulation is generated according to the control signal after above-mentioned optimization by rf signal generator to believe
Number for driving phase-modulator, system closed loop is realized, to guarantee to reach the best of SBS effect in the case that line width is as narrow as possible
Inhibitory effect.Finally, system will combine SBS effect and inhibit to inhibit with TMI effect, realize high brightness narrow linewidth Yb dosed optical fiber
The efficient amplification of laser.
In the utility model: mixing ytterbium main amplifier includes 1018nm pumping source, signal-pump combiner, doped fiber, packet
Layer light stripper；The pump light and light beam passes through letter derived from the output arm of high-power coupler that 1018nm pumping source exports
Number-pump combiner carry out close Shu Houjing doped fiber transmission, the Excited state mixed in ytterbium main amplifier is greatly lowered, realize
The efficient inhibition of the thermotropic unstable effect of mode (TMI) guarantees that the high brightness of narrow linewidth Yb dosed optical fiber laser is promoted.Doped fiber
It is connected with cladding light stripper, remaining pump light and cladding light are filtered out free space, prevent covering by cladding light stripper
Light damages output device, guarantees high light beam quality output.Wherein 1018nm pumping source implementation is unlimited, can be straight
High-power oscillator, super-fluorescence light source, random fiber laser etc. are connect, the master oscillation power amplification system of multi-stage cascade is also possible to
System.The 1018nm pumping source line width is unlimited, can be narrow cable and wide optical fiber laser, is also possible to wide range optical fiber laser.
Signal-pump combiner is made of signal input arm, pumping arm, signal output arm, wherein from the output arm of high-power coupler
Derived light beam is inputted by signal input arm, and the pump light of 1018nm pumping source output is inputted by pumping wall, is closed through signal-pumping
Beam device closes the output of Shu Houcong signal output arm.Doped fiber can consider the output of number multikilowatt high brightness, adulterate light there are many selection
Fine core diameter is general > 20 μm, the cladding thickness of doped fiber it is general > 200 μm.
The utility model combines the unstable effect of thermotropic mode (TMI) and non-linear stimulated Brillouin scattering effect
(SBS) inhibit, realize that the principle of high brightness narrow linewidth Yb dosed optical fiber laser amplifier is as follows:
In narrow linewidth optical fiber laser amplifier, the threshold formula of SBS is indicated are as follows:
Wherein a is fiber core radius, LeffFor equivalent optical fiber length, gB(vB) it is brillouin gain coefficient, Γ is spot size
With the ratio of fiber core radius, G is the amplification factor of amplifier.
When using rf signal generator driving phase-modulator, single frequency optical fiber laser seed source spectral line width will be by
Broadening, broadening of spectral lines directly result in effective brillouin gain spectrum widening, gB(vB) be greatly lowered, SBS threshold is effectively mentioned
It rises.In general, line width broadening is more, corresponding effective brillouin gain spectrum is wider, gB(vB) smaller, the inhibitory effect of SBS
Better.However, the excessive broadening of line width will lead to the light source time in many application fields of high brightness narrow linewidth fiber amplifier
Coherence's deterioration, influences performance of the light source in real application systems.For example, in optics coherence tomography field, the excessive broadening of spectrum
Caused time coherence sexual involution will affect the effect and system complexity of optics coherence tomography；In Spectral beam combining field, the mistake of spectrum
Degree broadening will affect the beam quality of synthesis system and can synthesize number；In non-linear wavelength conversion art, the excessive exhibition of spectrum
Width will affect the efficiency of non-linear conversion；In fields such as laser communication, coherent radar, remote sensings, the excessive broadening meeting of spectrum
It influences laser and transmits detection range.Therefore, for a set of actual high brightness narrow linewidth optical fiber amplification system, it need to guarantee line width
Reach the optimal inhibition effect of SBS effect in the case where as narrow as possible.For this reason, it may be necessary to optimize and control to modulated signal
System.When SBS effect occurs, backward stokes light will show the trend steeply risen and time domain representation is pulse type
State, the anomalous variation of this backward light echo can be used as the evaluation function of modulated signal optimization design and control.In the utility model,
By using high-power coupler, the subsequent reversed light echo generated in ytterbium main amplifier of mixing is exported, and then is injected into signal and adopts
Set processor carries out signal processing and optimization algorithm executes.Optimization algorithm executes the control signal generated and is applied to radio frequency source, increases
The adjustable electrical amplifier of benefit, bandwidth is adjustable electricity bandpass filter, just can be effectively controlled the Annual distribution of modulated signal, amplitude and
Bandwidth realizes the optimal inhibition effect of SBS effect in the case where guaranteeing that output linewidth is as narrow as possible.
The physics root that TMI is generated is that high brightness narrow linewidth MOPA structure mixes heat caused by Excited state in ytterbium main amplifier
Effect.The Excited state of fiber amplifier and pumping wavelength and transmitting optical maser wavelength are closely related.Pumping wavelength and transmitting laser
Wavelength is closer, and fiber amplifier Excited state is smaller, and the unstable threshold value of mode is higher.However, in traditional high brightness narrow linewidth
In MOPA system, inhibits SBS to shorten fiber lengths as far as possible, mix ytterbium main amplifier and generally 976nm is used to pump, cause
Amplifier Excited state is big, and the unstable threshold value of mode is low.TMI and SBS effect inhibit the utility model in order to balance, are narrow linewidth
The further luminance raising of Yb dosed optical fiber laser provides new idea and method, mixes ytterbium main amplifier pumping source and chooses 1018nm optical fiber
Laser.Compared with the laser diode-pumped mode of traditional 976nm, 1018nm optical fiber laser has higher brightness and smaller
Excited state.By taking 1064nm laser amplifier as an example, 976nm is used to pump the quantum efficiency of lower fiber amplifier as 91.7%
(Excited state 8.3%), and use 1018nm to pump the quantum efficiency of lower fiber amplifier (Excited state is only for 95.7%
4.3%) 50% is had dropped when, Excited state is pumped compared with 976nm.
Single frequency optical fiber laser seed source implementation described in the utility model is unlimited, can be distributed Feedback and swashs
Light device, Distributed Bragg Reflection laser, non-planar ring oscillator, single-frequency annular optical fiber laser, are also possible to single-frequency
Semiconductor laser passes through the laser light source of fiber coupling output.Single frequency optical fiber laser seed source central wavelength occurrence is not
Limit, usually any wavelength in covering 1060nm to 1100nm wavelength band.
Phase-modulator described in the utility model is generally electrooptic modulator, is commonly inserted and lower, modulation bandwidth is lost
It is higher, half-wave voltage is lower, to system realize advantageously.
Rf signal generator described in the utility model is by radio frequency source, adjustable gain electrical amplifier, bandwidth adjustable electric
Bandpass filter is learned to constitute.Radio frequency source is put to generate radiofrequency signal, the radiofrequency signal that radio frequency source generates through adjustable gain electricity
Big device realizes amplification, the amplification radiofrequency signal of adjustable gain electrical amplifier output again through the adjustable electricity bandpass filter of bandwidth with
The sideband components for filtering out amplification radiofrequency signal prevent the broadening of line width caused by sideband efficiency and the decline of SBS inhibitory effect.Wherein:
Its implementation of radio frequency source is unlimited, can be arbitrary waveform generator, white noise sound source, pseudo-random phase coding source, sine and cosine letter
Number generate bundling device etc..It amplifies bandwidth and is determined by the bandwidth of radiofrequency signal adjustable gain electrical amplifier, and amplification factor can be
Line is adjusted.
The pre- of seed laser is put after Yb dosed optical fiber laser preamplifier system described in the utility model realizes phase-modulation
Greatly.The series of pre-amplification is determined by expected magnification multiple.In view of the damage threshold of phase-modulator is generally in hundred milliwatt magnitudes,
Its power need to generally be amplified using two-stage prime amplifier, reach tens of watts of magnitudes.
High-power coupler described in the utility model is made of input arm, output arm and light echo monitoring arm, general to use
Optical fiber fused tapering mode realizes, in order to reduce loss as far as possible, the transmitance of output arm to input arm is general > and 99%, output
The splitting ratio of arm to light echo arm is general < 1%, i.e. light beam wherein 99% or more light after the input of the input arm of high-power coupler
Beam is exported from the output arm of high-power coupler, remaining (< 1%) light beam is exported from high-power coupler light echo monitoring arm.
End caps described in the utility model are the laser that passive optical fiber and the blocky head of quartz pass through fused biconical taper production
Transmitting device, to reduce optical fiber output end face laser power density, protection amplification system safety.
The laser alignment that end caps export is output to free space by collimator described in the utility model；Collimator can
To be realized by one or more lens combinations；The material of lens selects multiplicity, can be fused quartz, ZnSe, CaF2 etc..
High reflective mirror used by the utility model (high reflective mirror I and high reflective mirror II) realizes the high reflection function of amplification laser,
Its constituent material is unlimited, can be fused quartz, K9 etc., selects with specific reference to irradiation laser power density.Reflectance ratio of high reflected mirror is not
Limit, for several multikilowatt high brightness narrow linewidth fiber laser systems, generally requires reflectivity > 99.9%.
Power meter described in the utility model is for receiving into the laser come in and measuring its output power.
Photodetector described in the utility model realizes the conversion of optical signal to electric signal, photosurface material and size
It is unlimited, it can be according to selection there are many transmitting optical maser wavelengths；In order to detect TMI effect, generally require photodetector respective bandwidth >
2kH。
Beam splitter implementation multiplicity described in the utility model, can be white tiles, wedge-shaped mirrors etc., the composition material of beam splitter
Expect unlimited, can be fused quartz, K9, ZnSe, CaF2 etc..
Optical spectrum instrumentation described in the utility model realizes the on-line measurement of output laser spectrum, the resolution of optical spectrum instrumentation
Rate and Free Spectral Range selection are determined by the central wavelength and line width of laser after amplifying.
Beam quality measuring instrument described in the utility model is used for the beam quality of on-line measurement incident laser.
Signal acquisition process device described in the utility model is by photoelectric converter and the controller structure for being loaded with optimization algorithm
At the optical signal received is changed into voltage signal by photoelectric converter, and voltage signal importing is loaded with optimization algorithm
Controller.The controller for being loaded with optimization algorithm executes optimization algorithm according to the voltage signal that photoelectric converter provides, and generates control
Signal processed, and the control signal of generation is applied to radio frequency source, adjustable gain electrical amplifier, bandwidth is adjustable electricity bandpass filtering
Device realizes system closed loop.Be loaded with optimization algorithm controller its load optimization algorithm multiplicity, can be genetic algorithm, with
Machine parallel gradient descent algorithm, climbing method etc..
Compared with prior art, the utility model can generate following technical effect:
1, the utility model, which mentions, takes into account SBS effect and the inhibition of TMI effect.
For SBS effect, which judges the threshold that SBS effect occurs using the light echo monitoring arm of high-power coupler
Value, converts optical signals to voltage signal by signal acquisition process device, and servo gives optimization algorithm controller, provides corresponding
Signal is controlled, and then is applied to the radio frequency source in rf signal generator, adjustable gain electrical amplifier, bandwidth is adjustable electricity band
Bandpass filter realizes the optimization of spectral characteristic, and the best suppression of SBS effect is realized in the case where guaranteeing that output linewidth is as narrow as possible
Effect processed.
For TMI, the Excited state for mixing ytterbium main amplifier is effectively reduced using 1018nm pumping source for the utility model, realizes
The efficient inhibition of TMI.
2, the utility model has versatility.
For wave-length coverage being amplified, the utility model can be used for any wave in 1060nm~1100nm wavelength band
Long amplification；
For polarization characteristic, the utility model both can be applied to non-polarization-maintaining narrow linewidth Yb dosed optical fiber MOPA structure,
It can be applied to polarization-maintaining narrow linewidth Yb dosed optical fiber MOPA structure.
3, in the utility model, 1018nm pumping source implementation is unlimited, can be direct high-power oscillator, superfluorescence
Light source, random fiber laser etc. are also possible to the master oscillation power amplification system of multi-stage cascade.The 1018nm pumping source
Line width is unlimited, can be narrow cable and wide optical fiber laser, is also possible to wide range optical fiber laser.
4, in the utility model, single frequency optical fiber laser seed source implementation is unlimited, can be distributed feedback laser
Device, Distributed Bragg Reflection laser, non-planar ring oscillator, single-frequency annular optical fiber laser are also possible to single-frequency half
Conductor laser passes through the laser light source of fiber coupling output；Radiofrequency signal implementation is unlimited, can be random waveform
Device, white noise sound source, pseudo-random phase coding source, cosine and sine signal generate bundling device etc..
Detailed description of the invention
Fig. 1 is the system structure schematic illustration of the utility model.
Include: in figure single frequency optical fiber laser seed source 1, phase-modulator 2, rf signal generator 3, radio frequency source 3-1,
Adjustable gain electrical amplifier 3-2, bandwidth is adjustable electricity bandpass filter 3-3, Yb dosed optical fiber laser preamplifier system 4, Gao Gong
Rate coupler 5 mixes ytterbium main amplifier 6,1018nm pumping source 6-1, signal-pump combiner 6-2, doped fiber 6-3, cladding light
Stripper 6-4, end caps 7, collimator 8, high reflective mirror I 9, high reflective mirror II 10, power meter 11, photodetector 12, beam splitting
Device 13, beam quality measuring instrument 15, signal acquisition process device 16, photoelectric converter 16-1, is loaded with optimization at optical spectrum instrumentation 14
The controller 16-2 of algorithm.
Specific embodiment
Fig. 1 is the structural schematic diagram of one specific embodiment of the utility model, a kind of realization high brightness narrow linewidth Yb dosed optical fiber
The system of laser amplifier, including single frequency optical fiber laser seed source 1, phase-modulator 2, rf signal generator 3, Yb dosed optical fiber
Laser preamplifier system 4, high-power coupler 5 mix ytterbium main amplifier 6, end caps 7, collimator 8, high reflective mirror I9, high reflective mirror
II10, power meter 11, photodetector 12, beam splitter 13, optical spectrum instrumentation 14, beam quality measuring instrument 15, at signal acquisition
Manage device 16.
The output end tail optical fiber of single frequency optical fiber laser seed source 1 is connected to phase-modulator 2.Rf signal generator 3 drives
Dynamic phase-modulator 2, the line width of single frequency optical fiber laser seed source 1 is broadened.Broadening of spectral lines directly results in effective Brillouin
Gain spectrum widening, brillouin gain are greatly lowered, and realize effective inhibition of SBS effect.
Laser after phase-modulator 2 is first poured into the progress power of Yb dosed optical fiber laser preamplifier system 4 and puts in advance
Greatly.Light beam after 4 pre-amplification of Yb dosed optical fiber laser preamplifier system after the input of the input arm of high-power coupler 5 wherein
99% or more light beam is exported from the output arm of high-power coupler 5, remaining (less than 1%) light beam is from high-power coupler 5
Light echo monitor arm export, derived from the output arm of high-power coupler 5 light beam be injected into mix ytterbium main amplifier 6 carry out it is final
High power amplification.The light beam exported from the light echo of high-power coupler 5 monitoring arm is injected into signal acquisition process device 16, and signal is adopted
Set processor 16 is connect with rf signal generator 3；The optical signal of input is converted to electric signal by signal acquisition process device 16, and
Optimum control signal is generated to rf signal generator 3 according to the variation of electric signal, is generated by rf signal generator 3 optimal
Phase modulated signal is for driving phase-modulator 2.
Rf signal generator 3 is by radio frequency source 3-1, adjustable gain electrical amplifier 3-2, bandwidth is adjustable electricity bandpass filtering
Device 3-3 is constituted.Broadening of spectral lines directly results in effective brillouin gain spectrum widening, and brillouin gain is greatly lowered, and realizes SBS
Effective inhibition of effect.
Signal acquisition process device 16 is made of photoelectric converter 16-1 with the controller 16-2 for being loaded with optimization algorithm.From height
The light beam of the light echo monitoring arm output of power coupler 5 is injected into photoelectric converter 16-1, and photoelectric converter 16-1 believes light
Number electric signal is converted to, and servo gives optimization algorithm controller 16-2.When non-linear stimulated Brillouin scattering effect (SBS) occurs
When, the laser power exported from the light echo of high-power coupler 5 monitoring arm will show exponential increase trend and time domain representation is
Giant-pulse state.Therefore the voltage signal of photoelectric converter 16-1 output will appear apparent non-linear growth trend and shakiness
Fixed, the anomalous variation of photoelectric converter 16-1 output signal can be used as the evaluation function of optimization algorithm controller 16-2.
The controller 16-2 for being loaded with optimization algorithm executes optimization algorithm based on the electric signal that photoelectric converter 16-1 is exported
Find optimal time domain waveform control signal, gain voltage control signal and bandwidth adjustment voltage control signal, and by above-mentioned control
Signal processed is applied separately to radio frequency source 3-1, adjustable gain electrical amplifier 3-2, bandwidth adjustable electric in rf signal generator 3
Learn bandpass filter 3-3.Corresponding phase-modulation is generated according to the control signal after above-mentioned optimization by rf signal generator to believe
Number for driving phase-modulator, system closed loop is realized, to guarantee to reach the best of SBS effect in the case that line width is as narrow as possible
Inhibitory effect.Finally, system will combine SBS effect and inhibit to inhibit with TMI effect, realize high brightness narrow linewidth Yb dosed optical fiber
The efficient amplification of laser.
Mixing ytterbium main amplifier 6 includes 1018nm pumping source 6-1, signal-pump combiner 6-2, doped fiber 6-3, covering
Light stripper 6-4；The pump light and light beam is logical derived from the output arm of high-power coupler 5 that 1018nm pumping source 6-1 is exported
It crosses signal-pump combiner 6-2 to carry out closing Shu Houjing doped fiber 6-3 transmission, the amount mixed in ytterbium main amplifier 6 is greatly lowered
Son loss, realizes the efficient inhibition of the unstable effect of thermotropic mode (TMI), guarantees that the high brightness of narrow linewidth Yb dosed optical fiber laser mentions
It rises.Doped fiber 6-3 is connected with cladding light stripper, and remaining pump light and cladding light are filtered out freedom by cladding light stripper
Space prevents cladding light from damaging to output device, guarantees high light beam quality output.Wherein 1018nm pumping source implementation
It is unlimited, it can be direct high-power oscillator, super-fluorescence light source, random fiber laser etc., be also possible to the master of multi-stage cascade
Hunting power amplification system.The 1018nm pumping source line width is unlimited, can be narrow cable and wide optical fiber laser, is also possible to width
Compose optical fiber laser.Signal-pump combiner is made of signal input arm, pumping arm, signal output arm, wherein from high power coupling
Light beam derived from the output arm of clutch 5 is inputted by signal input arm, and the pump light of 1018nm pumping source 6-1 output is defeated by pumping wall
Enter, closes the output of Shu Houcong signal output arm through signal-pump combiner 6-2.Doped fiber can consider thousands of watts there are many selection
Grade high brightness output, doped fiber fibre core is general > 20 μm, covering it is general > 200 μm.
Laser by mixing the output of ytterbium main amplifier 6 is output to collimator 8,8 beam-expanding collimation of collimator through end caps 7
It is output to free space.The laser for collimating output is successively injected into power meter after high reflective mirror I 9 and high reflective mirror II 10 reflection
11.The light beam transmitted through high reflective mirror I 9 is received by photodetector 12, and photodetector 12 converts optical signals to electric signal.
The output when generating TMI or SBS effect in fiber amplifier can be used to observe according to the electric signal of photodetector output to swash
The time domain and frequency domain of light change, and successively judge the threshold value of TMI and SBS.Specifically, when SBS effect occurs in MOPA system, light
The very high giant-pulse of peak value can occur in continuous substrate in time-domain signal on electric explorer 12；When there is TMI in MOPA system, light
Time-domain signal will appear unstable on electric explorer 12, show as the unexpected overstriking of time-domain signal.If carrying out Fu to time-domain signal
In leaf transformation, then 2kHz nearby apparent characteristic envelope or characteristic peak will occur.
The laser transmitted through high reflective mirror II 10 is divided into two beams after beam splitter 13, wherein reflected through beam splitter 13
Light beam injects optical spectrum instrumentation 14, realizes the test to output laser spectrum distribution and line width, the light transmitted through beam splitter 13
Beam is incident on beam quality measuring instrument 15, for observing and monitoring the light beam of output laser during whole system power ascension
Mass change.
The foregoing is merely the preferred embodiments of the utility model, are not intended to limit the utility model, for
For those skilled in the art, various modifications and changes may be made to the present invention.All spirit and original in the utility model
Within then, any modification, equivalent replacement, improvement and so on be should be included within the scope of protection of this utility model.
Claims (10)
1. a kind of system for realizing high brightness narrow linewidth Yb dosed optical fiber laser amplifier, it is characterised in that: including single frequency fiber laser
Device seed source, rf signal generator, Yb dosed optical fiber laser preamplifier system, high-power coupler, mixes ytterbium master at phase-modulator
Amplifier, end caps, collimator, high reflective mirror I, high reflective mirror II, power meter, photodetector, beam splitter, optical spectrum instrumentation,
Beam quality measuring instrument, signal acquisition process device；
The output end tail optical fiber of single frequency optical fiber laser seed source is connected to phase-modulator, and rf signal generator drives phase tune
Device processed broadens the line width of single frequency optical fiber laser seed source；
Laser after phase-modulator is first poured into Yb dosed optical fiber laser preamplifier system and carries out power pre-amplification；Through mixing
Light beam after ytterbium optical-fiber laser preamplifier system pre-amplification is from a portion light beam after the input of the input arm of high-power coupler
It is exported from the output arm of high-power coupler, rest part light beam is from the monitoring arm export of the light echo of high-power coupler, from Gao Gong
Light beam derived from the output arm of rate coupler, which is injected into, to be mixed ytterbium main amplifier and carries out final high power amplification；It is coupled from high power
The light beam of the light echo monitoring arm output of device is injected into signal acquisition process device, and signal acquisition process device and rf signal generator connect
It connects；The optical signal of input is converted to electric signal by signal acquisition process device, and generates optimum control letter according to the variation of electric signal
Number rf signal generator is given, optimal phase modulated signal is generated for driving phase-modulator by rf signal generator,
Realization system closed loop；
Laser after mixing ytterbium main amplifier power amplification is output to collimator through end caps, and collimator beam-expanding collimation is defeated
Free space is arrived out；The laser for collimating output is successively injected into power meter after high reflective mirror I and high reflective mirror II reflection；Through high reflective mirror
The light beam of I transmission is received by a photoelectric detector, and photodetector converts optical signals to electric signal；Swash through what high reflective mirror II was transmitted
Light is divided into two beams after beam splitter, wherein the light beam gone out through beam splitter reflection injects optical spectrum instrumentation, realizes to output laser
The test of spatial distribution and line width is incident on beam quality measuring instrument through the light beam that beam splitter transmits, for observing and monitoring
The beam quality variation of laser is exported during whole system power ascension.
2. the system according to claim 1 for realizing high brightness narrow linewidth Yb dosed optical fiber laser amplifier, it is characterised in that: root
When being used to observe the output laser when generating TMI or SBS effect in fiber amplifier according to the electric signal of photodetector output
Domain and frequency domain variation, judge the threshold value of TMI and SBS according to this.
3. the system according to claim 1 for realizing high brightness narrow linewidth Yb dosed optical fiber laser amplifier, it is characterised in that: penetrate
Frequency signal generator by radio frequency source, adjustable gain electrical amplifier, bandwidth is adjustable, and electricity bandpass filter is constituted, radio frequency source to
Radiofrequency signal is generated, the radiofrequency signal that radio frequency source generates is realized through adjustable gain electrical amplifier amplifies, and adjustable gain electricity is put
The amplification radiofrequency signal of big device output filters out the sideband components of amplification radiofrequency signal through the adjustable electricity bandpass filter of bandwidth again.
4. the system according to claim 3 for realizing high brightness narrow linewidth Yb dosed optical fiber laser amplifier, it is characterised in that: letter
Number Acquisition Processor is by photoelectric converter and is loaded with the controller of optimization algorithm and constitutes；It is monitored from the light echo of high-power coupler
The light beam of arm output is injected into photoelectric converter, and photoelectric converter converts optical signals to electric signal, and servo is calculated to optimization
Method controller；When non-linear stimulated Brillouin scattering effect occurs, swash from what the light echo of high-power coupler monitoring arm exported
Optical power will show exponential increase trend and time domain representation is giant-pulse state, and the voltage signal of photoelectric converter output can go out
Now apparent non-linear growth trend and unstable, the anomalous variation of photoelectric converter output signal can be used as optimization algorithm control
The evaluation function of device processed；
It is loaded with after the controller of optimization algorithm executes optimization algorithm output optimization based on the electric signal that photoelectric converter exports
Signal is controlled, control signal includes that time domain waveform controls signal, gain voltage control signal and bandwidth adjustment voltage control signal,
Each control signal is applied separately to radio frequency source, adjustable gain electrical amplifier, bandwidth adjustable electric in rf signal generator
Learn bandpass filter；Corresponding phase modulated signal is generated according to the control signal after above-mentioned optimization by rf signal generator to use
In driving phase-modulator, system closed loop is realized.
5. the system according to claim 4 for realizing high brightness narrow linewidth Yb dosed optical fiber laser amplifier, it is characterised in that: add
Be loaded with optimization algorithm controller its load optimization algorithm be genetic algorithm, random paralleling gradient descent algorithm or climbing method.
6. according to claim 1 to realization high brightness narrow linewidth Yb dosed optical fiber laser amplifier described in any claim in 5
System, it is characterised in that: mixing ytterbium main amplifier includes 1018nm pumping source, signal-pump combiner, doped fiber and cladding light
Stripper；The pump light and light beam passes through signal-pump derived from the output arm of high-power coupler that 1018nm pumping source exports
Pu bundling device carries out closing the transmission of Shu Houjing doped fiber, and doped fiber is connected with cladding light stripper, and cladding light stripper will be residual
Remaining pump light and cladding light filters out free space, and wherein signal-pump combiner is by signal input arm, pumping arm, signal
Output arm is constituted, and light beam is inputted by signal input arm derived from the output arm of high-power coupler, the output of 1018nm pumping source
Pump light inputted by pumping wall, close the output of Shu Houcong signal output arm through signal-pump combiner.
7. the system according to claim 6 for realizing high brightness narrow linewidth Yb dosed optical fiber laser amplifier, it is characterised in that: mix
Core diameter > 20 μm of veiling glare fibre, doped fiber cladding thickness > 200 μm.
8. the system according to claim 1 for realizing high brightness narrow linewidth Yb dosed optical fiber laser amplifier, it is characterised in that: single
Frequency optical fiber laser seed source is distributed feedback laser, Distributed Bragg Reflection laser, non-planar ring oscillator
Or single-frequency annular optical fiber laser；Or single frequency optical fiber laser seed source is that single-frequency semiconductor laser passes through fiber coupling
The laser light source of output.
9. the system according to claim 1 for realizing high brightness narrow linewidth Yb dosed optical fiber laser amplifier, it is characterised in that: mix
Ytterbium optical-fiber laser preamplifier system uses two-stage prime amplifier；The reflectivity of high reflective mirror I and high reflective mirror II is equal > and 99.9%；Photoelectricity
Detector respective bandwidth > 2kH.
10. the system according to claim 1 for realizing high brightness narrow linewidth Yb dosed optical fiber laser amplifier, it is characterised in that:
Transmitance>99% of its output arm of high-power coupler to input arm, splitting ratio<1% of the output arm to light echo arm.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108512023A (en) * | 2018-05-29 | 2018-09-07 | 中国人民解放军国防科技大学 | System for realizing high-brightness narrow-linewidth ytterbium-doped optical fiber laser amplification |
| CN111564750A (en) * | 2020-05-18 | 2020-08-21 | 中国人民解放军国防科技大学 | System and method for inhibiting stimulated Brillouin scattering effect in high-power narrow-linewidth optical fiber laser amplifier |
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2018
- 2018-05-29 CN CN201820812720.1U patent/CN208522239U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108512023A (en) * | 2018-05-29 | 2018-09-07 | 中国人民解放军国防科技大学 | System for realizing high-brightness narrow-linewidth ytterbium-doped optical fiber laser amplification |
| CN108512023B (en) * | 2018-05-29 | 2023-08-25 | 中国人民解放军国防科技大学 | System for realizing high-brightness narrow-linewidth ytterbium-doped fiber laser amplification |
| CN111564750A (en) * | 2020-05-18 | 2020-08-21 | 中国人民解放军国防科技大学 | System and method for inhibiting stimulated Brillouin scattering effect in high-power narrow-linewidth optical fiber laser amplifier |
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