CN106768873B - A kind of method and device measuring high-fineness fineness of cavity - Google Patents
A kind of method and device measuring high-fineness fineness of cavity Download PDFInfo
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Abstract
The invention belongs to laser spectrum tech field, specially a kind of method and device for measuring high-fineness fineness of cavity.Solve existing low measurement accuracy, the technical problem high to detector required precision when measurement high-fineness cavity parameter at present.The present invention utilizes frequency locking technology, scans the second modulating frequency with light intensity signal and depicts the cavity mold shape of high-fineness cavity, accuracy is had more from principle.For the present invention due to having used frequency locking technology in measurement process, light-chamber is constantly in lock state, avoids the opposite drift of light-chamber frequency, and single measurement result credibility is high.The present invention is of less demanding to detector response time in the measurements；Since cavity mold width is generally in KHz magnitude, measurement detector bandwidth is not needed too greatly, this ensures that the detector precision used can be very high yet.
Description
Technical field
It is the high-fineness fineness of cavity measurement generallyd use for laboratory the invention belongs to laser spectrum tech field
A kind of new method, specially it is a kind of measure high-fineness fineness of cavity method and device.
Background technique
As optical resonator, Fabry-Perot interferometer (F-P cavity) just divides in spectroscopy and spectrum from the beginning of its research and development
Consequence is occupied in analysis, has been widely used in terms of optical frequency calibration, optical detection, optical detection.Description F-P cavity has
Multiple parameters, including Free Spectral Range, fineness, resolving power, angle dispersion etc..These parameters are in the selection of F-P cavity
With very important directive significance, we can also calculate the above parameter by traditional equation, but calculate thick
Slightly property is not able to satisfy requirement of the people now to small measurement, especially in the optical measurement of ultraprecise.Therefore, one is found
Kind is directed to the measurement method of F-P cavity parameter, and this method is simple, convenient, can quickly come into operation, and answers for any
With meaning a great for the experiment measurement of F-P cavity.
Erbium doped fiber laser (EDFL) has output light wavelength as the super-narrow line width laser to grow up in recent years
The advantages that stabilization, line width (hundred Hz), power stability, is widely applied to spectrum analysis, spectral measurement, non-linear spectral pumping
In terms of source.General cavity mold full width at half maximum (FWHM) is compared in tens KHz magnitudes, optical fiber laser can be competent at as survey completely
Measure the light source of cavity mold full width at half maximum.
F-P cavity cavity mirrors reflectivity is higher namely the biggish type of fineness is called high-fineness cavity, and people are common at present
Method to measure high-fineness fineness of cavity is cavity ring-down spectroscopy (CRDS), it by measure die-away time of intracavitary light field into
Row conversion obtains a series of parameters about high-precision chamber to obtain the specular reflectivity of chamber.In cavity-type BPM method, one
Beam short-pulse laser (light beam pulsewidth is less than light in the one week time of intracavity round trip), injection high-fineness was intracavitary, and laser can be intracavitary
Roundtrip, since hysteroscope has certain transmission loss, each secondary reflection all can have a certain proportion of light transmission to go out outside chamber, this
The light of fractional transmission just constitutes declining for chamber and swings signal.It is a signal in e index attenuated form that this, which declines and swings signal, with public affairs
Formula:
Fitting can obtain the ring-down time t of the intracavitary light of high-precision0, y0It is constant related with detector with A.Do not have intracavitary
In the case where having corresponding optical maser wavelength absorbent, the ring-down time of measurement and the reflectance relationship of high-fineness cavity hysteroscope are as follows:
And the relational expression between the reflectivity of hysteroscope and the fineness of chamber:
C is the light velocity, L in formula0It is the geometrical length of high-fineness cavity, R is required specular reflectivity, and F is the fine of chamber
Degree.
It is assumed that the only generation of transmission and reflex when light is radiated in high-precision chamber hysteroscope, namely
T+R=1 (4)
The transmissivity of T expression hysteroscope.
CRDS method is people using the measurement most common method of high-fineness cavity parameter at present, but CRDS still there are four
Disadvantage.First, in measurement, the long L of chamber0It can not directly obtain by this method, gauger also needs using other accurate instrument
Device measures chamber length, and the accuracy of the long measurement of chamber limits the measured value of high-fineness fineness of cavity.Second, CRDS measurement
Be the intracavitary light intensity attenuation time, therefore it can only be directed to super high-fineness cavity measurement, when fineness chamber hysteroscope reflection
When rate declines, the die-away time of intracavitary light intensity is easy to slip down to and can compare with the reaction time of measuring instrument, such as hundred ns amounts
Grade, the ring-down time precision that measurement obtains in this way will be well below the measurement to high-fineness cavity.Third, even for superelevation essence
Fineness chamber, since the response of different detectors is different, the ring-down time signal of measurement is also made a world of difference.4th, cavity-type BPM method
Data collecting card acquisition mass data is generallyd use averagely come the accuracy for improving time of measuring, when consuming very much in actual life
Between.
Therefore realistic consideration is combined, it is also very desirable to a method of measurement high-fineness cavity parameter, this method are not only fitted
Super high-fineness cavity together in reflectivity 99.99% or so, the high-fineness cavity slightly lower for reflectivity are also suitble to；And it is square
Just quick, it is suitble to most of detector measurements.
Summary of the invention
The invention proposes new method-double modulation methods that one kind can measure high-precision chamber.
A kind of method measuring high-fineness fineness of cavity of the present invention adopts the following technical solutions realization: one
The method of kind measurement high-fineness fineness of cavity, comprising the following steps: (1) to the laser of laser output plus first modulation
Frequency, the laser as carrier frequency can generate symmetrical two sidebands, i.e. sideband -1 and sideband 1, sideband -1 and sideband 1 by with to
The high-fineness cavity effect of survey generates error signal, and the centre frequency of laser emitting laser is locked to by the feedback of error signal
The center of high-fineness cavity cavity mold；First modulating frequency is greater than less than one free spectral range of overall with of cavity mold；(2) right
Laser adds second modulating frequency x, and the size of the modulating frequency is approximately equal to the big of one times of free spectral range of high-fineness cavity
Small, at this moment laser can generate symmetrical two sidebands, i.e. sideband -2 and sideband 2, second modulating frequency be scanned, in this way to be measured
The transmission end of high-fineness cavity can obtain a fluctuating about light intensity, the shape of light intensity fluctuation corresponds to high-fineness cavity chamber
The shape of mould；(3) lorentzian curve for the high-fineness cavity cavity mold pattern cavity mold that scanning obtains is fitted:
The fineness F of high-fineness cavity can be immediately arrived at；
In formula, x represents the frequency of the intracavitary transmitted light of high-precision, and y represents the light intensity of transmitted light, y0It with A is had with detector
The constant of pass, F are the finenesses of high-fineness cavity, and FSR is one times of free spectral range frequency of the high-fineness cavity that measurement obtains.
Fig. 1 shows the schematic diagrams of measurement.The cavity mold of high-fineness cavity is a lorentzian curve, for super-narrow line width laser
For device, when carrying out frequency modulation(PFM) to laser, the laser as carrier frequency can generate symmetrical two sidebands, i.e. sideband -1 and side
Band 1, sideband -1 and sideband 1 generate error signal by acting on high-fineness cavity, and the feedback of error signal is by the center of laser
When Frequency Locking is to the center of high-fineness cavity cavity mold, laser and high-fineness cavity resonance can all transmit chamber, at this time thoroughly
The light intensity penetrated is the largest.As long as theoretically first modulating frequency is greater than less than one free spectral range of overall with of cavity mold
To use, universal locking can use MHz magnitude.Later to laser plus second modulation, size approximation of modulating frequency etc.
Size in high-fineness cavity free spectral range, at this moment laser can generate symmetrical two sidebands, sideband -2 and sideband 2, scanning
Second modulating frequency can obtain a fluctuating about light intensity in the transmission end of chamber in this way, and the shape of fluctuating corresponds to high-precision
The shape of fineness chamber cavity mold.When second modulating frequency is just equal to the size of high-precision chamber free spectral range during the scanning process
When, through light intensity maximum, when modulating frequency is far from high-fineness cavity free spectral range, it is gradually reduced through light intensity.It scans
To the lorentzian curve of cavity mold pattern cavity mold be fitted:
Immediately arrive at the fineness F of high-fineness cavity.
In formula, y0It is constant related with detector with A；F is the fineness of high-fineness cavity；FSR measurement obtains
One times of free spectral range frequency of high-fineness cavity.
A kind of device measuring high-fineness fineness of cavity of the present invention adopts the following technical solutions realization: one
Kind measurement high-fineness fineness of cavity device, including laser, sequentially be located at laser emitting optical path on the first electric light tune
Device processed, the second electrooptic modulator, matching lens, 1/2 wave plate, polarization splitting prism；It is set on the transmitted light path of polarization splitting prism
There is quarter wave plate, high-fineness cavity to be measured is located on the emitting light path of quarter wave plate, on the emitting light path of high-fineness cavity sequentially
Equipped with the first condenser lens and the first detector, the signal output end of the first detector is connected with oscillograph；Polarization splitting prism
Reflected light path on the second condenser lens and the second detector is arranged in sequence；The rf inputs mouth of second electrooptic modulator connects
There is voltage controlled oscillator, the signal input part of voltage controlled oscillator is connected with first function generator, first function generator and oscillography
Device is connected；
It further include second function generator, the signal output end of second function generator is connected with beam splitter, beam splitter
First output port is connected with the rf inputs mouth of the first electrooptic modulator, and the second output terminal mouth of beam splitter is sequentially connected with
There are phase shifter, frequency mixer, low-pass filter, proportional integral circuit and high-voltage amplifier；The signal output end of high-voltage amplifier with
The voltage modulated port of laser is connected；The signal output end of second detector is connected with frequency mixer.
Measurement scheme is as shown in Figure 2.
Erbium doped fiber laser is emitted optical signal and passes through the first electrooptic modulator, and the second electrooptic modulator is by fiber exit mouth
Emit laser, after overmatching lens, by 1/2 wave plate, polarization splitting prism and quarter wave plate are irradiated to mirror before high-fineness cavity
On.Mirror reflected light enters the second detector through the second condenser lens before high-fineness cavity, and the light for entering F-P cavity is poly- by first
Focus lens enter the first detector.Second function generator generates radiofrequency signal, and a branch of signal enters first after beam splitter
Laser is modulated in electrooptic modulator, after another beam signal enters phase shifter, the optical signal that is detected with the second detector
It is mixed into frequency mixer, after low-pass filter, error signal is sent into proportional integral circuit simultaneously.Proportional integral circuit
Laser is locked by high-voltage amplifier.After locking, it is w that voltage controlled oscillator, which generates centre frequency,0MHz is (by right
The frequency of the Free Spectral Range for the rough chamber that the long survey calculation of chamber obtains) signal, while first function generator produces
Raw scanning signal enters in voltage controlled oscillator, makes voltage controlled oscillator with w0It is frequency scanned centered on MHz, voltage controlled oscillator signal
Secondary modulation is carried out to laser into fiber electro-optic modulator, the first detector samples cavity mold signal.
To further illustrate that this double modulation method measures the superiority of cavity mold fineness method, inventor is differently
The measurement of fineness has been carried out to same high-fineness cavity.Measurement result is as shown in Figure 3, Figure 4.Fig. 3 and 4 indicates to use cavity-type BPM
The ring-down time and fitting result of spectrographic technique measurement.(model: PDA 10CS-EC, THORLABS are public using detector a by Fig. 3
Department), Fig. 4 uses detector b (model: PDA 10CF-EC, THORLABS company), is shown using e index fitting formula (1), visits
Surveying the ring-down time that device a measurement obtains is 1.10969us, and the ring-down time that detector b measurement obtains is 1.10094us.Using
High-fineness cavity the long L of chamber0It is 2.997 × 10 for 394mm, light velocity c8M/s, these parameters are brought into formula (2) (3) can be with
The fineness for obtaining the chamber that detector a measurement obtains is 2651, and the fineness for the chamber that detector b measurement obtains is 2630.
Fig. 5 and Fig. 6 is the result using double modulation method measurement high-fineness cavity cavity mold.Fig. 5 using detector a (model:
PDA 10CS-EC, THORLABS company), Fig. 6 uses detector b (model: PDA 10CF-EC, THORLABS company), with public affairs
Formula (5) fitting display, the fineness for the chamber that detector a measurement obtains are 2615；The fineness for the chamber that detector b measurement obtains is
2613。
More generally, detector a has different gains, and different gains means the different bandwidth and difference of detector
Response time.It is carried out declining under different gains with cavity-type BPM method swinging measurement and the fitting of signal, as a result such as Fig. 7.It obtains
The ring-down time measured under 0dB, 10dB, 20dB, 30dB gain be respectively 1.10152us, 1.11004us,
1.11896us, 1.15864us, the fineness that chamber is calculated with formula (2) (3) is respectively 2631,2652,2673,2768.Make
The cavity mold such as Fig. 8 measured under 0dB, 10dB, 20dB, 30dB gain with the method for detector a double modulation, obtained fineness
Respectively 2615,2617,2609,2618.Using detector b, we are measured with double modulation method and cavity-type BPM method respectively
100 groups of signals simultaneously are fitted to obtain the fineness of chamber and residual error, and measurement result is as shown in Figure 9.
Left figure figure a is the high-fineness fineness of cavity measured using double modulation method in Fig. 9, and right figure figure b is declined using chamber
The high-precision fineness of cavity of oscillation method measurement, the following figure are corresponding residual errors being fitted with average value.Fitted figure in comparison diagram 9
As it can be seen that the high-fineness fineness of cavity fluctuating for using double modulation method to measure is smaller, regression criterion is smaller, and data are more
It is accurate credible.Also, the fineness of the chamber of cavity-type BPM method measurement has certain difference with double modulation method in terms of average value, this is
Because cavity-type BPM method has very strong dependence, furthermore derivation of the cavity-type BPM method in formula to the response time of detector
Cheng Zhongyou certain approximation, these approximations are built upon the reflectivity of high-fineness cavity hysteroscope close to 1 and intracavitary only saturating
Penetrate with the generation of reflex, when high-fineness cavity cavity mirrors reflectivity decline when, the approximation method of cavity-type BPM formula can introduce
Large error.
The fineness for the chamber that final double modulation method obtains is
F=2613.8 ± 5.3 (6)
It is using the fineness that cavity-type BPM method obtains chamber
F=2639.9 ± 25.5 (7)
The measurement result of comparison cavity-type BPM method and dual modulation method can be seen that cavity-type BPM method and excessively rely on measurement
The responsive bandwidth of middle electron servo and response time, this influences ring-down time huge for the measurement of us magnitude.Chamber declines
Oscillation method is in order to improve measurement accuracy, it will usually with ring-down time of the data collecting card to measurement carry out a large amount of data sampling with
Time is average, and sampling takes a long time, and data processing time is long, is unfavorable for current allegro production and living.Double modulation method benefit
With frequency locking technology, the second modulating frequency is scanned with light intensity signal and depicts cavity mold shape, with more accurate from principle
Property.And process light-the chamber scanned is in the lock state, and avoids the opposite drift of light-chamber frequency, and multiple measurement results are basic
It is consistent；Due to lock state, the quick response of detector is not needed, most photodetectors on the market can be opened up
Open such measurement.
The technology of the present invention has the advantage that compared with other phase similar techniques
1, the technology of the present invention proposes a kind of new method and device that can be used for measuring high-fineness cavity cavity mold fineness.
2, the present invention utilizes frequency locking technology, scans the second modulating frequency with light intensity signal and depicts high-fineness cavity
Cavity mold shape, from principle have more accuracy.
3, due to having used frequency locking technology in measurement process, light-chamber is constantly in lock state, avoids the present invention
Light-chamber frequency is opposite to drift about, and single measurement result credibility is high, compares some measurements for needing mass data average result
For save time of measuring, be conducive to current fast pace life.
4, of less demanding to detector response time in measurement；Since cavity mold width is generally in KHz magnitude, measurement detector
Bandwidth does not need too greatly yet, this ensures that the detector precision used can be very high, because detector bandwidth is bigger general
Its noise is also bigger.Illustrate that the present invention can realize under many detectors, and can achieve the measurement of higher precision.
Detailed description of the invention
Fig. 1 is the principal diagram that the present invention-double modulation method measures high-precision fineness of cavity.Carrier frequency is laser frequency, sideband-
1, which is first with sideband+1, modulates the double-side band generated, for light-chamber Frequency Locking；Sideband -2 and sideband+2 are second
The double-side band generated is modulated, cavity mold signal can be drawn in photodetector one end by scanning it.
Fig. 2 is the experimental provision structural schematic diagram of double modulation method.1- laser, the first electrooptic modulator of 2-, the second electricity of 3-
Optical modulator, 4- laser output, 5- match lens, 6-1/2 wave plate, 7- polarization splitting prism, 8-1/4 wave plate, 9- fine
Spend chamber, the first condenser lens of 10-, the first detector of 11-, the second condenser lens of 12-, the second detector of 13-, 14- first function
Generator, 15- voltage controlled oscillator, 16- second function generator, 17- beam splitter, 18- phase shifter, 19- frequency mixer, 20- low pass
Filter, 21- proportional integral circuit, 22- high-voltage amplifier；Wherein laser 1 uses 1531nm optical fiber laser.
Fig. 3 is the image of the high-precision chamber data measured at detector PDA 10CS-EC using cavity-type BPM method.■ in figure
It is the cavity-type BPM pattern measured under the detector using cavity-type BPM method, black line is formula (1) fitting pattern.
Fig. 4 is the image of the high-precision chamber data measured at detector PDA 10CF-EC using cavity-type BPM method.■ in figure
It is the cavity-type BPM pattern measured under the detector using cavity-type BPM method, black line is formula (1) fitting pattern.
Fig. 5 is the image of the high-precision chamber data measured at detector PDA 10CS-EC using double modulation method.■ in figure
It is the cavity mold pattern measured under the detector using double modulation method, black line is formula (5) fitting pattern.
Fig. 6 is the image of the high-precision chamber data measured at detector PDA 10CF-EC using double modulation method.■ in figure
It is the cavity mold pattern measured under the detector using double modulation method, black line is formula (5) fitting pattern.
Fig. 7 is the image for measuring high-precision chamber data under detector PDA 10CS-EC different gains using cavity-type BPM method.
■ is the cavity-type BPM pattern measured under the detector different gains using cavity-type BPM method in figure, and black line is formula (1)
It is fitted pattern.
Fig. 8 is the image for measuring high-precision chamber data under detector PDA 10CS-EC different gains using double modulation method.
■ is the cavity-type BPM pattern measured under the detector different gains using cavity-type BPM method in figure, and black line is formula (5)
It is fitted pattern.
Fig. 9 is measured at same detector PDA10CF-EC using double modulation method and cavity-type BPM method obtain respectively
100 groups of finesse values.■ is that measurement obtains scatterplot value, and black line is average value fitting image, and the following figure is regression criterion；A schemes in the middle
It is the value and fitting measured using double modulation method, b figure is the value and fitting measured using cavity-type BPM method.
Specific embodiment
A method of measurement high-fineness fineness of cavity, comprising the following steps: (1) laser of laser output is added
First modulating frequency, the laser as carrier frequency can generate symmetrical two sidebands, i.e. sideband -1 and sideband 1, sideband -1 and side
Band 1 generates error signal by acting on high-fineness cavity to be measured, and the feedback of error signal will be in laser emitting laser
Frequency of heart is locked to the center of high-fineness cavity cavity mold；As long as theoretically first modulating frequency is greater than the overall with of cavity mold less than one
A free spectral range can use, and universal locking can use MHz magnitude, use herein for our experimental provision bandwidth
25MHz optimal frequency；(2) second modulating frequency is added to laser, the size of the modulating frequency is approximately equal to high-fineness cavity
The size of free spectral range, uses formula
It is available.Wherein c is the light velocity 2.997 × 108M/s, n are inner cavity refractive index, usually take 1, L under gas station0It is
It is long to measure obtained high-fineness cavity chamber, is accurate to mm.At this moment laser can generate symmetrical two sidebands, i.e. sideband -2 and sideband
2, second modulating frequency is scanned, a fluctuating about light intensity can be obtained in the transmission end of high-fineness cavity to be measured in this way,
The shape of light intensity fluctuation corresponds to the shape of high-fineness cavity cavity mold；(3) the high-fineness cavity cavity mold pattern for obtaining scanning is used
The lorentzian curve of cavity mold is fitted:
The fineness F of high-fineness cavity can be immediately arrived at.
Multiple high-fineness cavity finesse values can be taken multiple measurements and obtained after being fitted in step (3), then acquired
The average value of one high-fineness fineness of cavity.
It is a kind of measure high-fineness fineness of cavity device, including laser 1, sequentially be located at 1 emitting light path of laser on
The first electrooptic modulator 2, the second electrooptic modulator 3, matching lens 5,1/2 wave plate 6, polarization splitting prism 7；Polarization spectro rib
The transmitted light path of mirror 7 is equipped with quarter wave plate 8, and high-fineness cavity 9 to be measured is located on the emitting light path of quarter wave plate 8, fine
It spends on the emitting light path of chamber 9 and the first condenser lens 10 and the first detector 11 is arranged in sequence, the signal output of the first detector 11
End is connected with oscillograph；The second condenser lens 12 and the second detector 13 are arranged in sequence on the reflected light path of polarization splitting prism 7；
The rf inputs mouth of second electrooptic modulator 3 is connected with voltage controlled oscillator 15, the signal input part connection of voltage controlled oscillator 15
There is first function generator 14, first function generator 14 is connected with oscillograph；
It further include second function generator 16, the signal output end of second function generator 16 is connected with beam splitter 17, point
First output port of beam device 17 is connected with the rf inputs mouth of the first electrooptic modulator 2, the second output of beam splitter 17
Port has been sequentially connected with phase shifter 18, frequency mixer 19, low-pass filter 20, proportional integral circuit 21 and high-voltage amplifier 22；It is high
The signal output end of pressure amplifier 22 is connected with the voltage modulated port of laser 1；The signal output end of second detector 13
It is connected with frequency mixer 19.
First electrooptic modulator 2, the second electrooptic modulator 3 use fiber electro-optic modulator.
The technology of the present invention is further described with reference to the accompanying drawing.
Erbium doped fiber laser is emitted optical signal and passes through the first electrooptic modulator 2, and the second electrooptic modulator 3 is exported by laser
Mouth 4 emits laser, and after overmatching lens 5, by 1/2 wave plate 6, polarization splitting prism 7 and quarter wave plate 8 are irradiated to fine
Before degree chamber 9 on mirror.Mirror reflected light enters the second detector 13 through the second condenser lens 12 before high-fineness cavity 9, enters high-precision
The light of fineness chamber enters the first detector 11 by the first condenser lens 10.Second function generator 16 generates 25MHZ radio frequency letter
Number, a branch of signal is modulated laser into entering in the first electrooptic modulator 2 after beam splitter 17, and another beam signal enters
After phase shifter 18, enters frequency mixer 19 with the optical signal that the second detector 13 detects and be mixed, by low-pass filter 20
Afterwards, error signal is sent into proportional integral circuit 21 simultaneously.Proportional integral circuit 21 carries out laser by high-voltage amplifier 22
Locking.After locking, it is that 380MHz (is obtained substantially by the survey calculation long to chamber that voltage controlled oscillator 15, which generates centre frequency,
Chamber Free Spectral Range) signal, secondary modulation, while the first letter are carried out to laser into the second electrooptic modulator 3
Number generator 14 generates frequency 1HZ, and the scanning signal of ± 450mv enters in voltage controlled oscillator 15, make voltage controlled oscillator 15 with
It is frequency scanned centered on 380MHz, the first detector 11 will measure the light intensity signal changed over time, by the first detector
11 are connected on oscillograph, it can be seen that a complete cavity mold profile.The 1HZ that first function generator 14 is generated, ±
The scanning signal beam splitting of 450mv enters oscillograph, and oscillograph can receive under same time scale, the amplitude of scanning voltage and
The amplitude of cavity mold signal, by table look-up it is known that voltage controlled oscillator 15 plus voltage value and voltage controlled oscillator output frequency it
Between corresponding relationship, be converted into frequency values with voltage, frequency values imported under origin together with cavity mold signal and are fitted just
Relationship between available frequency and cavity mold amplitude.
Claims (5)
1. a kind of method for measuring high-fineness fineness of cavity, which comprises the following steps: (1) exported to laser
Laser add first modulating frequency, the laser as carrier frequency can generate symmetrical two sidebands, i.e. sideband -1 and sideband 1,
By acting on generation error signal with high-fineness cavity to be measured, the feedback of error signal goes out laser for sideband -1 and sideband 1
The centre frequency for penetrating laser is locked to the center of high-fineness cavity cavity mold；The overall with that first modulating frequency is greater than cavity mold is small
In a free spectral range；(2) second modulating frequency is added to laser, the size of the modulating frequency is approximately equal to high-fineness
The size of one times of free spectral range of chamber, at this moment laser can generate symmetrical two sidebands, i.e. sideband -2 and sideband 2, scanning second
A modulating frequency can obtain a fluctuating about light intensity in the transmission end of high-fineness cavity to be measured in this way, light intensity fluctuation
Shape corresponds to the shape of high-fineness cavity cavity mold；(3) long-range navigation for the high-fineness cavity cavity mold pattern cavity mold for obtaining scanning
Hereby line style is fitted:
Immediately arrive at the fineness F of high-fineness cavity；
In formula, x represents the frequency of the intracavitary transmitted light of high-precision, and y represents the light intensity of transmitted light, y0It is related with detector normal with A
Number, F are the finenesses of high-fineness cavity, and FSR is one times of free spectral range frequency of the high-fineness cavity that measurement obtains.
2. a kind of method for measuring high-fineness fineness of cavity as described in claim 1, which is characterized in that can in step (3)
Multiple high-fineness cavity finesse values are taken multiple measurements and obtained after being fitted, a high-fineness fineness of cavity is then acquired
Average value.
3. a kind of device for measuring high-fineness fineness of cavity, for realizing method according to claim 1 or 2；Its feature
Be, including laser (1), sequentially be located at laser (1) emitting light path on the first electrooptic modulator (2), the second electric light tune
Device (3) processed, matching lens (5), 1/2 wave plate (6), polarization splitting prism (7)；It is set on the transmitted light path of polarization splitting prism (7)
Have quarter wave plate (8), high-fineness cavity (9) to be measured is located on the emitting light path of quarter wave plate (8), and high-fineness cavity (9) goes out
It penetrates in optical path and the first condenser lens (10) and the first detector (11) is arranged in sequence, the signal output end of the first detector (11) connects
It is connected to oscillograph；The second condenser lens (12) and the second detector are arranged in sequence on the reflected light path of polarization splitting prism (7)
(13)；The rf inputs mouth of second electrooptic modulator (3) is connected with voltage controlled oscillator (15), the signal of voltage controlled oscillator (15)
Input terminal is connected with first function generator (14), and first function generator (14) is connected with oscillograph；
It further include second function generator (16), the signal output end of second function generator (16) is connected with beam splitter (17),
First output port of beam splitter (17) is connected with the rf inputs mouth of the first electrooptic modulator (2), beam splitter (17)
Second output terminal mouth be sequentially connected with phase shifter (18), frequency mixer (19), low-pass filter (20), proportional integral circuit (21) and
High-voltage amplifier (22)；The signal output end of high-voltage amplifier (22) is connected with the voltage modulated port of laser (1)；Second
The signal output end of detector (13) is connected with frequency mixer (19).
4. a kind of device for measuring high-fineness fineness of cavity as claimed in claim 3, which is characterized in that the first Electro-optical Modulation
Device (2), the second electrooptic modulator (3) use fiber electro-optic modulator.
5. a kind of device of measurement high-fineness fineness of cavity as described in claim 3 or 4, which is characterized in that laser (1)
Using erbium doped fiber laser.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611024930.6A CN106768873B (en) | 2016-11-22 | 2016-11-22 | A kind of method and device measuring high-fineness fineness of cavity |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611024930.6A CN106768873B (en) | 2016-11-22 | 2016-11-22 | A kind of method and device measuring high-fineness fineness of cavity |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN106768873A CN106768873A (en) | 2017-05-31 |
| CN106768873B true CN106768873B (en) | 2018-12-07 |
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| CN108534986B (en) * | 2018-04-12 | 2020-03-31 | 安徽大学 | Multi-longitudinal-mode laser resonant cavity FSR measuring device and measuring method |
| CN108709717B (en) * | 2018-06-27 | 2020-04-07 | 安徽大学 | Device and method for measuring resonant cavity FSR of multi-longitudinal-mode laser by using large-amplitude laser self-mixing vibration signal |
| CN109580032B (en) * | 2018-11-15 | 2020-12-25 | 山西大学 | Ultra-stable optical cavity zero crossing temperature measuring device and measuring method |
| CN112161706B (en) * | 2020-09-22 | 2021-07-27 | 山西大学 | Device and method for quickly and accurately measuring free spectral region of optical cavity |
| CN118032304A (en) * | 2024-04-15 | 2024-05-14 | 上海频准激光科技有限公司 | Fine measurement method and device for F-P cavity |
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