CN110118643A - A kind of the laser linewidth measurement method and device of the extraction of power spectrum bicharacteristic parameter - Google Patents
A kind of the laser linewidth measurement method and device of the extraction of power spectrum bicharacteristic parameter Download PDFInfo
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- CN110118643A CN110118643A CN201910306123.0A CN201910306123A CN110118643A CN 110118643 A CN110118643 A CN 110118643A CN 201910306123 A CN201910306123 A CN 201910306123A CN 110118643 A CN110118643 A CN 110118643A
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Abstract
The laser linewidth measurement method and device extracted the invention discloses a kind of power spectrum bicharacteristic parameter.This method comprises: wherein two beams after shift frequency and delay are swashed combiner, detect the photoelectric current of combined beam light and obtain its power spectrum by beam of laser shift frequency, the delay of another beam of laser by testing laser beam splitting；Extract the characteristic parameter of power spectrum: the frequency difference of the power difference of single order envelope peak and valley, zeroth order minimum point and centre frequency；The line width values of testing laser are calculated according to the characteristic parameter of extraction.The device includes: that testing laser is divided into first laser and second laser by light source module；Frequency displacement module is by first laser shift frequency；Second laser is delayed by time delay module；Power spectrum acquiring module is used to detect the photoelectric current of combined beam light and obtains its power spectrum；Data processing module calculates the line width values of testing laser for extracting characteristic parameter.The present invention can lead to the problem of laser linewidth measurement inaccuracy to avoid time delay optical fiber length-measuring error in the prior art.
Description
Technical field
The invention belongs to laser linewidth fields of measurement, extract more particularly, to a kind of power spectrum bicharacteristic parameter
Laser linewidth measurement method and device.
Background technique
Narrow linewidth laser has the characteristics that output laser rays width, coherence are good, in fiber optic communication and Fibre Optical Sensor
Equal fields receive significant attention.Line width, that is, phase noise characteristic of local oscillator light source in fiber optic communication systems, directly affects relevant
Effective extraction of phase information after demodulation.As modulation format used in system is more and more advanced, it is to source phase noise
The requirement of line width is increasingly stringenter, and line width size starts to develop from 1MHz magnitude to 10kHz even 100Hz magnitude.Conventional base
In the laser linewidth measurement method of delay self-heterodyne technology, kilometers up to a hundred are needed under conditions of testing laser device line width is very narrow
Time delay optical fiber, this can not only make entire measuring system have very big loss, can also introduce great phase noise, make to measure
As a result very big error is generated, is not able to satisfy the demand of existing super-narrow line width laser linewidth measurement.
(Huang S, Zhu T, Cao Z, the et al.Laser Linewidth Measurement Based of periodical literature 1
on Amplitude Difference Comparison of Coherent Envelope[J].IEEE Photonics
Technology Letters, 2016,28 (7): 759-762.) disclose a kind of coherence envelope amplitude detection super-narrow line width swash
The method of light device wire width measuring, this method, as time delay optical fiber, extract power spectrum single order envelope peak using one section of shorter optical fiber
The power difference of value and valley and the line width values that testing laser device is calculated by certain algorithm.In this approach, it needs
The length of time delay optical fiber is accurately obtained, and often there is a certain error for this measurement of length, and then makes laser line
Wide measurement result inaccuracy.
Summary of the invention
The purpose of the present invention is to provide a kind of laser linewidth measurement method and devices, to solve the prior art because of delay
The measurement error of fiber lengths leads to the problem of laser linewidth measurement inaccuracy.
To achieve the above object, the present invention provides the laser linewidth measurement sides that a kind of power spectrum bicharacteristic parameter extracts
Method, comprising:
Testing laser is divided into two beams, wherein beam of laser shift frequency, the delay of another beam of laser, by swashing after shift frequency and delay
Combiner detects the photoelectric current of combined beam light and obtains its power spectrum；
Extract the characteristic parameter of power spectrum；
The characteristic parameter includes: the power difference of single order envelope peak and valley, zeroth order minimum point and centre frequency
Frequency difference；
The line width values of testing laser are calculated according to the characteristic parameter of extraction.
Preferably, the another beam of laser is delayed using time delay optical fiber, time delay optical fiber are as follows:
The photoelectric current is detected using detector, the power spectrum of photoelectric current are as follows:
The power difference of single order envelope peak and valley in the power spectrum are as follows:
The frequency difference of zeroth order minimum point and centre frequency in the power spectrum are as follows:
Wherein, c indicates light velocity size；N indicates optical fibre refractivity size；P0Indicate the optical power value of combined beam light；Δ ν is indicated
The line width values of testing laser；The length of L expression time delay optical fiber；f0Indicate the size of frequency shift amount；α indicates the big of detector responsivity
It is small；G indicates the gain size of amplifier in detector；The size of R expression detector output resistance；ΔfrIndicate the power measured
The resolution sizes of spectrum；SR(f) power spectrum of photoelectric current is indicated；ΔSRIndicate the function of single order envelope peak and valley in power spectrum
Rate difference；ΔfRIndicate the frequency difference of zeroth order minimum point and centre frequency in power spectrum.
Preferably, the line width values of the testing laser are as follows:
Wherein, Δ SRIndicate the power difference of single order envelope peak and valley in power spectrum；ΔfRIndicate zeroth order in power spectrum
The frequency difference of minimum point and centre frequency；The line width values of Δ ν expression testing laser.
The present invention provides the laser linewidth measuring devices that a kind of power spectrum bicharacteristic parameter extracts, comprising: light source die
Block, frequency displacement module, time delay module, power spectrum acquiring module and data processing module；
First output end of the light source module is connected with the input terminal of frequency displacement module, second output terminal and time delay module
Input terminal is connected；The output end of the frequency displacement module is connected with the first input end of power spectrum acquiring module；The time delay module
Output end be connected with the second input terminal of power spectrum acquiring module；The output end of the power spectrum acquiring module and data processing
Module is connected；
The light source module is classified as first laser and second laser for generating testing laser；The frequency displacement mould
Block is by first laser shift frequency；Second laser is delayed by the time delay module；The power spectrum acquiring module is used for will be after shift frequency
Second laser coupling after first laser and delay, the light after detection coupling obtain photoelectric current and obtain its power spectrum；The number
It is used to extract the characteristic parameter in power spectrum according to processing module, and calculates the line width values of testing laser.
Preferably, the light source module includes laser and the first coupler；
The output end of the laser is connected with the input terminal of the first coupler；First output end of first coupler
It is connected with the input terminal of frequency displacement module, second output terminal is connected with the input terminal of time delay module；
The laser issues testing laser；First coupler is used to testing laser being divided into two beam laser；
Preferably, the light source module further includes optoisolator, the output of the input terminal and laser of the optoisolator
End is connected, and output end is connected with the input terminal of the first coupler, for protecting laser.
Preferably, the frequency displacement module includes frequency shifter and DC power supply；
The output end of the DC power supply is connected with an input terminal of frequency shifter；Another input terminal of the frequency shifter
It is connected with the first output end of the first coupler, output end is connected with the first input end of power spectrum acquiring module；
The DC power supply drives the frequency shifter for output signal；The frequency shifter is used for the first coupler transfer
Laser carry out shift frequency；
Preferably, the frequency displacement module further includes the first adjustable optical attenuator, the input of first adjustable optical attenuator
End is connected with the output end of the frequency shifter, and output end is connected with the first input end of power spectrum acquiring module；Described first
Adjustable optical attenuator is for the power between the laser after matching shift frequency and the laser after delay.
Preferably, the time delay module includes time delay optical fiber；
The input terminal of the time delay optical fiber is connected with the second output terminal of the first coupler, and output end and power spectrum obtain
Second input terminal of module is connected；
The time delay optical fiber is for the laser of the first coupler transfer to be delayed；
Preferably, the range of the time delay optical fiber length are as follows:
Wherein, c indicates light velocity size；N indicates optical fibre refractivity size；The line width values of Δ ν expression testing laser；L is indicated
The length of time delay optical fiber；ΔSminIndicate the minimum measurable magnitude of the power difference of single order envelope peak and valley；ΔfminIt indicates
The minimum measurable magnitude of the frequency difference of zeroth order minimum point and centre frequency；P0Indicate the optical power value of combined beam light；SnIt indicates to survey
The performance number of the system noise substrate obtained；The size of α expression detector responsivity；G indicates that the gain of amplifier in detector is big
It is small；The size of R expression detector output resistance；ΔfrIndicate the resolution sizes of the power spectrum measured.
Preferably, the time delay module further includes Polarization Controller and the second adjustable optical attenuator；The Polarization Controller
Input terminal be connected with the output end of time delay optical fiber, output end connect the second adjustable optical attenuator input terminal；Described second
The output end of adjustable optical attenuator is connected with the second input terminal of power spectrum acquiring module；The Polarization Controller prolongs for matching
When after laser and shift frequency after laser between polarization state；Second adjustable optical attenuator be used for match delay after laser and
The power between laser after shift frequency.
The power spectrum acquiring module includes the second coupler, optical detector and electron spectrum analyzer；
The first input end of second coupler is connected with the output end of the first adjustable optical attenuator, the second input terminal with
The output end of second adjustable optical attenuator is connected, and the first output end is connected with the input terminal of optical detector；The optical detector
Output end be connected with the input terminal of the electron spectrum analyzer；The output end and data of the electron spectrum analyzer are analyzed
The input terminal of module is connected；
Second coupler is used for the two beam laser for transmitting the first adjustable optical attenuator and the second adjustable optical attenuator
Coupling；The optical detector obtains photoelectric current for detecting coupling light；The electron spectrum analyzer is for obtaining photoelectric current
Power spectrum；
Preferably, the detection wavelength of the optical detector will cover the wavelength of testing laser, and detective bandwidth is greater than described
The frequency shift amount of frequency shifter；
The power spectrum acquiring module further includes light power meter；The second output terminal of the light power meter and the second coupler
It is connected, for monitoring the optical power in link.
The data analysis module includes electronic computer；
The input terminal of the electronic computer is connected with the output end of electron spectrum analyzer；
The electronic computer calculates the line width of testing laser for extracting characteristic parameter from the power spectrum obtained
Value.
Preferably, the characteristic parameter of the power spectrum includes: that the power difference of single order envelope peak and valley, zeroth order are minimum
Frequency difference of the value point with centre frequency.
Contemplated above technical scheme through the invention, compared with prior art, can obtain it is following the utility model has the advantages that
(1) present invention is by extracting the characteristic parameter in the photoelectric current power spectrum that detection obtains, specially single order envelope peak
The power difference Δ S of value and valleyR, zeroth order minimum point and centre frequency frequency difference Δ fR, pass through formulaThe line width values Δ ν for calculating testing laser, the invention avoids the prior arts because surveying to time delay optical fiber length
Amount error leads to the problem of laser linewidth measurement inaccuracy, keeps the laser linewidth value of measurement relatively reliable.
(2) laser linewidth measurement method proposed by the present invention will extract obtained characteristic parameter and be brought directly to formula meter
The line width values that testing laser can be obtained are calculated, it is easier compared to the method proposed in document 1.
Detailed description of the invention
Fig. 1 is the flow diagram of laser linewidth measurement method provided by the invention；
Fig. 2 is power spectrum provided by the invention and the characteristic parameter schematic diagram that need to be extracted；
Fig. 3 is the structural schematic diagram for the measuring system that embodiment 1 provides；
Fig. 4 is the time delay optical fiber to different length, when the error of time delay optical fiber length takes different value, the reality of testing laser
The relational graph of the error of border line width values and wire width measuring value.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
As shown in Figure 1, the present invention provides the laser linewidth measurement method that a kind of power spectrum bicharacteristic parameter extracts, packet
It includes:
(1) testing laser is divided into two beams, wherein beam of laser shift frequency, the delay of another beam of laser, after shift frequency and delay
Sharp combiner, detect the photoelectric current of combined beam light and obtain its power spectrum；
(2) characteristic parameter of power spectrum is extracted；
The characteristic parameter includes: the power difference of single order envelope peak and valley, zeroth order minimum point and centre frequency
Frequency difference；
(3) line width values of testing laser are calculated according to the characteristic parameter of extraction.
Preferably, another beam of laser is delayed using time delay optical fiber in the step (1), after detector pairing beam
Laser detected to obtain photoelectric current, use electron spectrum analyzer obtain photoelectric current power spectrum, time delay optical fiber are as follows:
Wherein, c indicates light velocity size；N indicates optical fibre refractivity size；The line width values of Δ ν expression testing laser；L is indicated
The length of time delay optical fiber；ΔSminIndicate the minimum measurable magnitude of the power difference of single order envelope peak and valley；ΔfminIt indicates
The minimum measurable magnitude of the frequency difference of zeroth order minimum point and centre frequency；P0Indicate the optical power value of combined beam light；SnIt indicates to survey
The performance number of the system noise substrate obtained；The size of α expression detector responsivity；G indicates that the gain of amplifier in detector is big
It is small；The size of R expression detector output resistance；ΔfrIndicate the resolution sizes of the power spectrum measured.
The wavelength of the detection wavelength covering testing laser of detector, bandwidth are greater than the size of frequency shift amount.
The centre frequency of power spectrum is equal to the size of frequency shift amount.
As shown in Fig. 2, repeating the characteristic parameter that step (2) extract power spectrum, multiple groups measurement data is obtained.
Preferably, multiple groups measurement data is brought into formula respectivelyCalculate the line width of testing laser
Value, is averaged later as last result；Wherein, Δ SRIndicate the difference power of single order envelope peak and valley in power spectrum
Value；ΔfRIndicate the frequency difference of zeroth order minimum point and centre frequency in power spectrum；The line width values of Δ ν expression testing laser.
As shown in figure 3, the present invention provides the laser linewidth measuring device that a kind of power spectrum bicharacteristic parameter extracts, packet
It includes: light source module, frequency displacement module, time delay module, power spectrum acquiring module and data processing module；
First output end of the light source module is connected with the input terminal of frequency displacement module, second output terminal and time delay module
Input terminal is connected；The output end of the frequency displacement module is connected with the first input end of power spectrum acquiring module；The time delay module
Output end be connected with the second input terminal of power spectrum acquiring module；The output end of the power spectrum acquiring module and data processing
The input terminal of module is connected；
The light source module is classified as first laser and second laser for generating testing laser；The frequency displacement mould
Block is by first laser shift frequency；Second laser is delayed by the time delay module；The power spectrum acquiring module is used for will be after shift frequency
Second laser coupling after first laser and delay, the light after detection coupling obtain photoelectric current and obtain its power spectrum；The number
It is used to extract the characteristic parameter of power spectrum according to processing module, and calculates the line width values of testing laser.
The light source module includes laser 1, optoisolator 2 and the first coupler 3；
The output end of the laser 1 is connected with the input terminal of optoisolator 2；The output end of the optoisolator 2 and
The input terminal of one coupler 3 is connected；First output end of first coupler 3 is connected with the input terminal of frequency displacement module, and second
Output end is connected with the input terminal of time delay module；
The laser 1 issues testing laser；The optoisolator 2 is for protecting laser；First coupler 3 is used
In testing laser is divided into two beam laser.
The frequency displacement module includes frequency shifter 4, DC power supply 5 and the first adjustable optical attenuator 6；
The output end of the DC power supply 5 is connected with an input terminal of frequency shifter 4；Another of the frequency shifter 4 is defeated
Enter end to be connected with the first output end of the first coupler 3, output end is connected with the input terminal of the first adjustable optical attenuator 6；Institute
The output end for stating the first adjustable optical attenuator 6 is connected with the first input end of power spectrum acquiring module；
The DC power supply 5 drives the frequency shifter 4 for output signal；The frequency shifter 4 is used for the first coupler
The laser of transmission carries out shift frequency；First adjustable optical attenuator 6 is between the laser after matching shift frequency and the laser after delay
Power.
The time delay module includes time delay optical fiber 7, Polarization Controller 8 and the second adjustable optical attenuator 9；
The input terminal of the time delay optical fiber 7 is connected with the second output terminal of the first coupler 3, output end and Polarization Control
The input terminal of device 8 is connected；The output end of the Polarization Controller 8 is connected with the input terminal of the second adjustable optical attenuator 9；Described
The output end of two adjustable optical attenuators 9 is connected with the second input terminal of power spectrum acquiring module；
The time delay optical fiber 7 is for the laser that the first coupler 3 transmits to be delayed；The Polarization Controller 8 is used for
The polarization state between the laser after laser and shift frequency after matching delay；After second adjustable optical attenuator 9 is for matching delay
Laser and shift frequency after laser between power；
The power spectrum acquiring module includes the second coupler 10, optical detector 11, electron spectrum analyzer 12 and light function
Rate meter 13；
The first input end of second coupler 10 is connected with the output end of the first adjustable optical attenuator 6, the second input
End is connected with the output end of the second adjustable optical attenuator 9, and the first output end is connected with the input terminal of optical detector 11；The light
The output end of detector 11 is connected with the input terminal of the electron spectrum analyzer 12；The output of the electron spectrum analyzer 12
End is connected with the input terminal of data processing module；The light power meter 13 is connected with the second output terminal of the second coupler 10；
Second coupler 10 is used for two beams for transmitting the first adjustable optical attenuator 6 and the second adjustable optical attenuator 9
Laser coupled；The optical detector 11 obtains photoelectric current for detecting coupling light；The electron spectrum analyzer 12 is for obtaining
The power spectrum of photoelectric current；The light power meter 13 is used to monitor the optical power in link.
The data processing module includes electronic computer 14；
The input terminal of the electronic computer 14 is connected with the output end of electron spectrum analyzer 12；
The electronic computer 14 for extracted from the power spectrum obtained single order envelope peak and valley power difference,
The frequency difference of zeroth order minimum point and centre frequency, and calculate the line width values of the laser 1.
It need to indicate, the description of the invention shown in Fig. 3, and not have limited；The wherein optical isolation in light source module
The first adjustable optical attenuator 6 in device 2, frequency displacement module, the Polarization Controller 8 in time delay module and the second adjustable optical attenuator 9,
Light power meter 13 in power spectrum acquiring module is not the corresponding essential features of present invention problem, can be according to reality
Situation is replaced or is deleted.
Core of the invention is the characteristic parameter in the photoelectric current power spectrum for extract combined beam light, calculates the line of testing laser device
Width values, concrete principle are as follows:
Conclusion in Source Journals document 1, what testing laser obtained after beam splitting, shift frequency, delay, conjunction beam and detection
Photoelectric current power spectrum S (f) are as follows:
Abscissa is frequency in S (f), and unit Hz, ordinate is power spectral density, unit mW/Hz.In formula (1), c
Indicate light velocity size；N indicates optical fibre refractivity size；P0Indicate the optical power value of combined beam light；The line width of Δ ν expression testing laser
Value；The length of L expression time delay optical fiber；f0Indicate the size of frequency shift amount.
The power spectral density difference DELTA S of single order envelope peak and valley can be indicated in power spectrum are as follows:
Formula (2) can indicate are as follows:
Δ S=10lg Δ S1ΔS2 (3)
Work as existence conditionIt has been generally acknowledged that working asWhen, formula (4) and formula (5) can have following abbreviation:
To Δ S2Taylor expansion is carried out, and it is available to cast out high-order term:
Joint type (2)-(7), available:
In above formula,It is equal to the frequency difference of zeroth order minimum point and centre frequency in the power spectrum of photoelectric current, into
One step can obtain:
WhereinIndicate the frequency difference of zeroth order minimum point and centre frequency in power spectrum.
It willIt is replaced with Δ f so that the parameter L in model is avoided replaced the measurable parameter Δ f in power spectrum
The problem of testing laser device wire width measuring inaccuracy caused by time delay optical fiber measurement of length error.
Fig. 4 show the time delay optical fiber for different length, to be measured to swash when the error of time delay optical fiber length takes different value
The relational graph of the error of the line width values and wire width measuring value of light device.As shown in Figure 4, in one timing of testing laser device line width, measurement
As a result the error of error and fiber lengths is substantially unrelated.
In actual measurement, photoelectric current usually is detected to obtain by detector, and photoelectric current power spectrum is obtained by frequency spectrograph, and
Represented by the obtained spectral pattern of frequency spectrograph can not be by formula (1), the spectral pattern abscissa that frequency spectrograph detects is frequency, and unit is
Hz, ordinate are power, unit mW, usually broadly also by this spectral pattern S in documentR(f) it is known as power spectrum, this power
Spectrum are as follows:
Wherein, α indicates the size of detector responsivity；G indicates the gain size of amplifier in detector；R indicates detection
The size of device output resistance；ΔfrIndicate the resolution sizes of the power spectrum measured.
MeetingI.e.Under conditions of, SR(f) difference power of single order envelope peak and valley in
It is worth Δ SRIt can indicate are as follows:
Above formula can be seen that the power difference Δ S of single order envelope peak and valley using frequency spectrograph actual measurementRAnd reason
Single order envelope peak is identical as the expression formula of power spectral density difference DELTA S of valley in, it may be assumed that
Δ S=Δ SR (12)
Since fiber lengths meetThe laser that bicharacteristic parameter under available actual conditions extracts
The calculation formula of testing laser device line width values in line width measuring method:
WhereinIndicate the frequency difference of zeroth order minimum point and centre frequency in power spectrum, it can be seen that practical
The frequency difference Δ f of zeroth order minimum point and centre frequency in measurementRWith the frequency of zeroth order minimum point and centre frequency in theory
Rate difference DELTA f's is equal in magnitude, are as follows:
So formula (13) are as follows:
Formula (15) is as can be seen that directly using the characteristic parameter Δ S extracted from the power spectrum that frequency spectrograph obtainsRWith Δ fR
The value that can replace Δ S and Δ f in theory, calculates the line width values of testing laser device.
If the power difference Δ S of single order envelope peak and valleyRMinimum detectable value be Δ Smin, then:
If the frequency difference Δ f of zeroth order minimum point and centre frequency in power spectrumRMinimum measurable magnitude be Δ fmin,
Then byIt can obtain:
On the other hand, the corresponding performance number of single order minimum point should be greater than corresponding to the noise floor of system in the measurements
Performance number, thus guarantee that single order minimum point will not be flooded by noise floor, therefore the above measurement method needs to meet:
Wherein, SnIndicate the performance number of the system noise substrate measured.
Joint type (11) and (20) can obtain:
Due to havingTherefore formula (21) can turn to:
Abbreviation obtains:
The value range of time delay optical fiber length L can to sum up be obtained are as follows:
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should all include
Within protection scope of the present invention.
Claims (9)
1. the laser linewidth measurement method that a kind of power spectrum bicharacteristic parameter extracts characterized by comprising
(1) testing laser is divided into two beams, wherein beam of laser shift frequency, the delay of another beam of laser, by swashing after shift frequency and delay
Combiner detects the photoelectric current of combined beam light and obtains its power spectrum；
(2) characteristic parameter of power spectrum is extracted；
The characteristic parameter includes: the frequency of the power difference of single order envelope peak and valley, zeroth order minimum point and centre frequency
Rate difference；
(3) line width values of testing laser are calculated according to the characteristic parameter of extraction.
2. laser linewidth measurement method as described in claim 1, which is characterized in that another beam of laser in the step (1)
It is delayed using time delay optical fiber, time delay optical fiber are as follows:
Wherein, L indicates the length of time delay optical fiber；C indicates light velocity size；N indicates optical fibre refractivity size；Δ ν indicates to be measured and swashs
The line width values of light device.
3. laser linewidth measurement method as claimed in claim 2, which is characterized in that use detector in the step (1)
It is detected, the power spectrum of photoelectric current in step (1) are as follows:
Wherein, c indicates light velocity size；N indicates optical fibre refractivity size；P0Indicate the optical power value of combined beam light；Δ ν indicates to be measured
The line width values of laser；The length of L expression time delay optical fiber；f0Indicate the size of frequency shift amount；The size of α expression detector responsivity；g
Indicate the gain size of amplifier in detector；The size of R expression detector output resistance；ΔfrIndicate the power spectrum measured
Resolution sizes；SR(f) power spectrum of photoelectric current is indicated.
4. laser linewidth measurement method as claimed in claim 3, which is characterized in that extract power spectrum in the step (2)
The power difference of middle single order envelope peak and valley includes:
(A) the corresponding performance number of single order envelope peak and the corresponding performance number of single order envelope valley are extracted respectively in power spectrum；
(B) it is poor to make the corresponding performance number of single order envelope peak and the corresponding performance number of single order envelope valley, obtains single order envelope
The power difference of peak value and valley；
The power difference of single order envelope peak and valley are as follows:
Wherein, c indicates light velocity size；N indicates optical fibre refractivity size；The line width values of Δ ν expression testing laser；L indicates delay
The length of optical fiber；ΔSRIndicate the power difference of single order envelope peak and valley in power spectrum.
5. laser linewidth measurement method as described in claim 3 or 4, which is characterized in that extract zeroth order in the step (2)
The frequency difference of minimum point and centre frequency includes:
(A) the corresponding frequency values of zeroth order minimum point and the corresponding frequency values of centre frequency are extracted respectively in power spectrum；
(B) it is poor to make the corresponding frequency values of zeroth order minimum point and the corresponding frequency values of centre frequency, obtains zeroth order minimum point
With the frequency difference of centre frequency.
The frequency difference of the zeroth order minimum point and centre frequency are as follows:
Wherein, c indicates light velocity size；N indicates optical fibre refractivity size；The length of L expression time delay optical fiber；ΔfRIndicate zeroth order pole
Frequency difference of the small value point with centre frequency.
6. laser linewidth measurement method as claimed in claim 5, which is characterized in that testing laser in the step (3)
Line width values are as follows:
Wherein, Δ SRIndicate the power difference of single order envelope peak and valley in power spectrum；ΔfRIndicate that zeroth order is minimum in power spectrum
Frequency difference of the value point with centre frequency；The line width values of Δ ν expression testing laser.
7. the laser linewidth measuring device that a kind of power spectrum bicharacteristic parameter extracts characterized by comprising light source module,
Frequency displacement module, time delay module, power spectrum acquiring module and data processing module；
First output end of the light source module is connected with the input terminal of frequency displacement module, the input of second output terminal and time delay module
End is connected；The output end of the frequency displacement module is connected with the first input end of power spectrum acquiring module；The time delay module it is defeated
Outlet is connected with the second input terminal of power spectrum acquiring module；The output end and data processing module of the power spectrum acquiring module
It is connected；
The light source module is classified as first laser and second laser for generating testing laser；The frequency displacement module will
First laser shift frequency；Second laser is delayed by the time delay module；The power spectrum acquiring module is used for first after shift frequency
Second laser coupling after laser and delay, the light after detection coupling obtain photoelectric current and obtain its power spectrum；At the data
Reason module is used to extract the characteristic parameter of power spectrum, and calculates the line width values of testing laser.
8. laser linewidth measuring device as claimed in claim 7, which is characterized in that the time delay module uses time delay optical fiber
It is delayed, the power spectrum acquiring module is detected using detector, time delay optical fiber are as follows:
Wherein, L indicates the length of time delay optical fiber；C indicates light velocity size；N indicates optical fibre refractivity size；Δ ν indicates to be measured and swashs
The line width values of light；ΔSminIndicate the minimum measurable magnitude of the power difference of single order envelope peak and valley；ΔfminIndicate zeroth order
The minimum measurable magnitude of the frequency difference of minimum point and centre frequency；P0Indicate the optical power value of combined beam light；SnWhat expression measured
The performance number of system noise substrate；The size of α expression detector responsivity；G indicates the gain size of amplifier in detector；R
Indicate the size of detector output resistance；ΔfrIndicate the resolution sizes of the power spectrum measured.
9. laser linewidth measuring device as claimed in claim 8, which is characterized in that the characteristic parameter packet of the power spectrum
It includes: the frequency difference of the power difference of single order envelope peak and valley, zeroth order minimum point and centre frequency.
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| CN201910306123.0A CN110118643B (en) | 2019-04-17 | 2019-04-17 | Laser line width measuring method and device for power spectrum double-characteristic parameter extraction |
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| CN201910306123.0A CN110118643B (en) | 2019-04-17 | 2019-04-17 | Laser line width measuring method and device for power spectrum double-characteristic parameter extraction |
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| CN115655663B (en) * | 2022-10-20 | 2024-02-06 | 中国航天三江集团有限公司 | Linewidth measurement method and system of all-fiber structure laser |
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