CN102841355A - Device and method for measuring data of femtosecond range laser radar based on microwave photonics - Google Patents

Abstract

The invention discloses a device and method for measuring real-time data of a femtosecond range laser radar based on microwave photonics. The method comprises the following steps of: converting a distance signal measured by the femtosecond range laser radar into a microwave pulse frequency signal; performing band-pass filtering on the microwave pulse frequency signal, and then amplifying; taking an amplified signal as a modulating signal and performing phase modulation on a carrier; and detecting a frequency of a first sideband signal of the carrier by an optical frequency identifier to obtain the frequency of the microwave pulse frequency signal. The device comprises a band-pass filter, a microwave amplifier, a single-frequency continuous light laser, an optical phase modulator, the frequency identifier, a detector, a photoelectric detector and an oscilloscope. According to the method and device provided by the invention, an optical border frequency identifying technology is combined, so that the problems of the traditional measuring method for the present real-time data of the femtosecond range laser radar that the response frequency is insufficient, the data storage requirement is high and the real-time closed-loop control is difficult to realize are solved.

Description

Femtosecond range laser radar data measurement unit and method based on microwave photon

Technical field

The invention belongs to femtosecond optical detection, microwave signal processing technology field, especially a kind of measurement mechanism and method of the femtosecond range laser radar real time data of learning based on microwave photon.

Background technology

Based on the signal of the femtosecond range laser radar of real-time chromatic dispersion Fourier transform, be an interference fringe on the time domain, belong to microwave pulse.In existing scheme, normally adopt high-speed photodetector to gather the time domain interference signal, use real-time sampling phosphorescence oscillograph that the electric signal of photodetector output is sampled and record then.But the oscillographic response frequency of real-time sampling phosphorescence is lower than the response frequency of high-speed photodetector usually, the dynamic range that this meeting restricting signal is measured; And, for the precision that guarantees to survey, the oscillographic SF of real-time sampling phosphorescence generally very high (the GHz order of magnitude).For long-time, real-time detection task, data volume is very big, and therefore, storage is a very big challenge for data in high speed for this.

At last; Because when monitoring the vibration at high speed target in real time; The repetition frequency of femto-second laser pulse very high (the MHz order of magnitude); And be to adopt first record data in the existing scheme, the follow-up way of handling again, this has just lost meaning for real-time monitoring and closed-loop control swiftly passing object (like magnetic suspension wipping top).

Summary of the invention

In view of the above problems, the present invention proposes a kind of measurement mechanism and method of the femtosecond range laser radar real time data of learning based on microwave photon.

According to an aspect of the present invention, propose a kind of femtosecond range laser radar real time data measuring method of learning based on microwave photon, it is characterized in that this method may further comprise the steps:

Step 1, the distance signal that will measure based on the femtosecond range laser radar of real-time chromatic dispersion Fourier transform is converted into the frequency signal of time domain interference fringe, i.e. microwave pulse frequency signal;

Step 2 is amplified said microwave pulse frequency signal through using microwave amplifier after the band-pass filter;

Step 3 as modulation signal, is carried out phase modulation (PM) to carrier wave with the microwave pulse frequency signal after amplifying, and wherein, the frequency of said microwave pulse frequency signal is corresponding to the centre frequency of said carrier wave first sideband signals;

Step 4, through Optical Frequency Discriminator, use edge method detects the frequency of said carrier wave first sideband signals, can obtain the frequency of said microwave pulse frequency signal.

Wherein, the logical scope of the band of said BPF. is 1-40GHz.

Wherein, said carrier wave adopts single-frequency continuous light laser instrument to produce.

Said step 4 further is: through detecting the variation of said carrier wave first sideband signals transmitance on frequency discriminator, the change of frequency of coming said carrier wave first sideband signals of inverting.

Wherein, said Optical Frequency Discriminator is the tandem fibre optic interferometer.

Said step 4 further may further comprise the steps:

Step 41 measures the ratio R of the two paths of signals signal intensity of said tandem fibre optic interferometer output ₁₂(ω _m);

Step 42 is according to the frequencies omega of the ratio and the said microwave pulse frequency signal of said signal intensity _mBetween relation try to achieve the frequencies omega of said microwave pulse frequency signal _m

The frequencies omega of the ratio of said signal intensity and said microwave pulse frequency signal _mBetween relation be:

$R_{12}\left({\mathrm{\ω}}_m\right)=\frac{2K^2{\tilde{T}}_1}{1+2K^2{\tilde{T}}_2({\mathrm{\ω}}_c+{\mathrm{\ω}}_m)},$

Wherein, k ₁Be near the slope of single order Bessel function zero point,

Be the index of modulation,

Be respectively the transmittance function of the two paths of signals of said tandem fibre optic interferometer output,

Phasing degree for carrier wave.

The transmittance function

respectively:

${\tilde{T}}_1\left(\mathrm{\ω}\right)=T_1\left(\mathrm{\ω}\right)*I^2\left(\mathrm{\ω}\right),$ ${\tilde{T}}_2\left(\mathrm{\ω}\right)=T_2\left(\mathrm{\ω}\right)*I^2\left(\mathrm{\ω}\right),$

Wherein, T ₁(ω), T ₂(ω) be respectively the intensity transfer function that said tandem fibre optic interferometer two-way is exported; I ²Be that the spectral intensity that is input to the signal of said tandem fibre optic interferometer distributes (ω).

According to a further aspect in the invention; A kind of measurement mechanism of the femtosecond range laser radar real time data of learning based on microwave photon is also proposed; It is characterized in that; This measurement mechanism comprises: BPF. 1, microwave amplifier 2, single-frequency continuous light laser instrument 3, optical phase modulator 4, frequency discriminator, detector 9 and photodetector 10, wherein:

Said BPF. 1 is used for the time domain microwave pulse frequency signal of the femtosecond range laser radar that is converted to is carried out filtering;

Said microwave amplifier 2 is used for amplifying through filtered signal;

Said single-frequency continuous light laser instrument 3 is used to produce carrier signal;

Said optical phase modulator 4 is used for as modulation signal said carrier signal being carried out phase modulation (PM) with the signal after amplifying through said microwave amplifier 2;

Said frequency discriminator is used to detect the frequency displacement of the carrier signal that obtains through said phase modulation (PM);

Said detector 9 is used to receive the two paths of signals of said frequency discriminator output with photodetector 10, and measures the signal strength values of this two paths of signals.

Wherein, said frequency discriminator is the tandem fibre optic interferometer.

Wherein, said tandem fibre optic interferometer comprises Polarization Controller 5, polarization maintaining optical fibre 6, Polarization Controller 7 and fibre optic polarizing beam splitter PBS8 successively.

Said measurement mechanism also comprises oscillograph 11, is used to receive, show and handle the signal that said detector 9 and photodetector 10 receive.

According to the ratio of the signal strength values of said two paths of signals and the frequencies omega of said microwave pulse frequency signal _mBetween relation try to achieve the frequencies omega of said microwave pulse frequency signal _mThe frequencies omega of the ratio of said signal strength values and said microwave pulse frequency signal _mBetween relation be:

$R_{12}\left({\mathrm{\ω}}_m\right)=\frac{2K^2{\tilde{T}}_1({\mathrm{\ω}}_c+{\mathrm{\ω}}_m)}{1+2K^2{\tilde{T}}_2({\mathrm{\ω}}_c+{\mathrm{\ω}}_m)},$

Wherein,

k ₁Be near the slope of single order Bessel function zero point, Be the index of modulation,

Be respectively the transmittance function of the two paths of signals of said frequency discriminator output,

Phasing degree for carrier wave.The transmittance function

respectively:

${\tilde{T}}_1\left(\mathrm{\ω}\right)=T_1\left(\mathrm{\ω}\right)*I^2\left(\mathrm{\ω}\right),$ ${\tilde{T}}_2\left(\mathrm{\ω}\right)=T_2\left(\mathrm{\ω}\right)*I^2\left(\mathrm{\ω}\right),$

Wherein, T ₁(ω), T ₂(ω) be respectively the intensity transfer function that said frequency discriminator two-way is exported; I ²Be that the spectral intensity that is input to the signal of said frequency discriminator distributes (ω).

The present invention combines the optical edge Frequency discrimination technology, and the traditional measurement method response frequency that has solved existing femtosecond range laser radar real time data is not enough, call data storage is high, and real-time closed-loop is controlled the problem that is difficult to realize.

Description of drawings

Fig. 1 is the synoptic diagram of the Bessel's function that adopts of the present invention.

Fig. 2 is the measuring method process flow diagram of the femtosecond range laser radar real time data of learning based on microwave photon that proposes of the present invention.

Fig. 3 is the measurement mechanism structural drawing of the femtosecond range laser radar real time data of learning based on microwave photon that proposes of the present invention.

Fig. 4 is that the present invention uses edge method to measure the schematic diagram of sideband centre frequency.

Fig. 5 is the femtosecond range laser radar real time data measuring system structural drawing that the present invention is based on real-time chromatic dispersion Fourier transform and microwave photon.

Embodiment

For making the object of the invention, technical scheme and advantage clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, to further explain of the present invention.

The femtosecond range laser radar is through launching femto-second laser pulse to target direction; Echoed signal on the target range and the femto-second laser pulse of being launched are interfered; Again the optical interference signals that produces is received by photodetector and be converted into the microwave pulse frequency signal, and the frequency information of this microwave pulse frequency signal is tested range information.

The ultimate principle of the microwave photon treatment technology that uses among the present invention is to use the phase place of the microwave pulse frequency signal modulation single-frequency continuous laser of femtosecond range laser radar output; And in the carrier wave (being modulated single-frequency continuous laser) centre frequency of first sideband signals just corresponding the frequency of microwave pulse, this frequency can obtain through the means of optics frequency discrimination.Wherein, the single-frequency continuous light is the basic terms in the laser technology, refers to the continuous laser of frequency single stable.

Fig. 2 is the measuring method process flow diagram of the femtosecond range laser radar real time data of learning based on microwave photon that proposes of the present invention; The femtosecond range laser radar real time data measuring method that handle based on microwave photon proposed by the invention has adopted microwave photon to learn signal processing method and edge method; Realized the measurement of femtosecond range laser radar real time data; As shown in Figure 2, this method comprises following step:

Step 1, the distance signal that will measure based on the femtosecond range laser radar of real-time chromatic dispersion Fourier transform is converted into the frequency signal of time domain interference fringe, i.e. microwave pulse frequency signal;

In femtosecond range laser radar based on real-time chromatic dispersion Fourier transform; The range information that measures is reflected as the form of the frequency information of time domain interference fringe; Be converted into the microwave pulse frequency information through photodetector more afterwards; Promptly for different measuring distances, the femtosecond range laser radar can be exported the microwave pulse signal of different frequency.

Step 2 is amplified said microwave pulse frequency signal through using microwave amplifier after the band-pass filter;

In one embodiment of the invention, the logical scope of the band of said BPF. is 1-40GHz.

Step 3 as modulation signal, is carried out phase modulation (PM) to carrier wave with the microwave pulse frequency signal after amplifying, and wherein, the frequency of said microwave pulse frequency signal is corresponding to the centre frequency of said carrier wave first sideband signals;

Particularly, the microwave pulse frequency signal after the said amplification is imported optical phase modulator as modulation signal, and said carrier wave is through just having received the phase modulation (PM) of microwave pulse frequency signal behind this optical phase modulator.

Said carrier wave adopts single-frequency continuous light laser instrument to produce; Carry the microwave pulse frequency information after being used to receive the modulation of microwave pulse frequency signal; In one embodiment of the invention, said single-frequency continuous light laser instrument is the 1550nm single-frequency continuous light laser instrument of live width less than 10KHz.

Introduce the ABC of Laser Modulation below:

Laser Modulation can be divided into amplitude modulation, frequency modulation, phase modulation etc. by the character of its modulation.Be that example is introduced below with the phase modulation.

Usually, the electric field intensity of laser light wave can be expressed as:

Wherein, A _cBe amplitude, ω _cBe angular frequency,

Be the phasing degree.Among the present invention, the electric field intensity of establishing carrier wave is shown in (1) formula.

If modulation signal is the cosine function of a time, promptly

a(t)＝A _m?cosω _mt (2)

In the formula, A _mBe the amplitude of modulation signal, ω _mIt is the angular frequency of modulation signal.So; Phase modulation (PM) just can make the phasing degree in (1) formula change along with the Changing Pattern of modulation signal, and total phase angle of the phase-modulation wave that phase modulation (PM) obtains is:

Wherein,

is scale-up factor (notion of introducing in the mathematics manipulation).And said phase-modulation wave just can be expressed as:

In the formula,

is called coefficient of phase modulation.

The brief analysis frequency spectrum of phase-modulation wave once more below.Because phase modulation in fact finally is the total phase angle of modulation, so it can be write as:

Wherein, m is the index of modulation.Utilize triangle formula to launch following formula, obtain:

With (the m sin w of the cos in the following formula _mT) and sin (m sin w _mT) press the following formula expansion for two:

$\cos \left(m\sin {\mathrm{\ω}}_{m}t\right)=J_0\left(m\right)+2\underset{n=1}{\overset{\∞}{\mathrm{\Σ}}}{J}_{2n}\left(m\right)\cos \left({2\mathrm{n\ω}}_{m}t\right)---\left(7\right)$

$\sin \left(m\sin {\mathrm{\ω}}_{m}t\right)=2\underset{n=1}{\overset{\∞}{\mathrm{\Σ}}}{J}_{2n-1}\left(m\right)\sin \left[(2n-1){\mathrm{\ω}}_{m}t\right]---\left(8\right)$

Can find out that from last two formulas the known modulation Coefficient m just can check in the value of each rank Bessel's function from the Bessel's function table.

To go up two formula substitution (6) formulas and expansion, can obtain:

This shows that when the single frequency sinusoidal ripple was modulated, the frequency spectrum of its angle modulated wave was by light carrier frequency and infinite manyly forming side frequency of being symmetrically distributed on its both sides.Frequency interval between each side frequency is ω _m, the big or small J of each side frequency amplitude _n(m) determine by Bessel's function.When angular modulation coefficient less (being m＜＜1), can know that by Bessel function shown in Figure 1 the side frequency that the high-order Bessel's function of n >=2 is corresponding can be ignored.

Step 4, through Optical Frequency Discriminator, use edge method detects the frequency of said carrier wave first sideband signals, can obtain the frequency of said microwave pulse frequency signal.

Said step 4 further is: through detecting the variation of said carrier wave first sideband signals transmitance on frequency discriminator, the change of frequency of coming said carrier wave first sideband signals of inverting.Optically, can directly use the tandem fibre optic interferometer to detect the frequency displacement of said carrier wave first sideband signals as frequency discriminator.

Said step 4 further may further comprise the steps:

Step 41 measures the ratio R of the two paths of signals signal intensity of said tandem fibre optic interferometer output ₁₂(ω _m);

Step 42 is according to the frequencies omega of the ratio and the said microwave pulse frequency signal of said signal intensity _mBetween relation try to achieve the frequencies omega of said microwave pulse frequency signal _m

Fig. 3 is the measurement mechanism structural drawing of the femtosecond range laser radar real time data of learning based on microwave photon that proposes of the present invention; The present invention adopts measurement mechanism as shown in Figure 3 that the microwave pulse frequency is directly measured; This measurement mechanism comprises: BPF. 1, microwave amplifier 2, single-frequency continuous light laser instrument 3, optical phase modulator 4, frequency discriminator, detector 9, photodetector 10 and oscillograph 11, wherein:

Said BPF. 1 is used for the time domain microwave pulse frequency signal of the femtosecond range laser radar that is converted to is carried out filtering;

Said microwave amplifier 2 is used for amplifying through filtered signal;

Said single-frequency continuous light laser instrument 3 is used to produce carrier signal;

Said optical phase modulator 4 is used for as modulation signal said carrier signal being carried out phase modulation (PM) with the signal after amplifying through said microwave amplifier 2;

Said frequency discriminator is used to detect the frequency displacement of the carrier signal that obtains through said phase modulation (PM);

Among the present invention; The frequency displacement of optically directly using the tandem fibre optic interferometer to come detected carrier first sideband signals as frequency discriminator, said tandem fibre optic interferometer comprise Polarization Controller 5, polarization maintaining optical fibre 6, Polarization Controller 7 and fibre optic polarizing beam splitter (PBS) 8 successively.

Said detector 9 is used to receive the two paths of signals of said frequency discriminator output with photodetector 10, and measures the signal strength values of this two paths of signals;

Said oscillograph 11 is used to receive, show and handle the signal that said detector 9 and photodetector 10 receive.

In order to discuss for simplicity, suppose not consider polarization mode dispersion and used non-equilibrium dispersion compensation the influence of third-order dispersion, then said microwave pulse frequency signal (time domain interference fringe) can be written as:

i ₁(t)cos[τt/β ₂L] (10)

Wherein, i ₁(t) be the external envelope of microwave pulse frequency signal, τ is the signal time difference in the femtosecond range laser radar, β ₂Be the secondary Taylor series of mould transmission, L is the length of the dispersion compensating fiber in the femtosecond range laser radar.

According to formula (3) and formula (4), when phase modulated signal was formula (10), coefficient of phase modulation no longer was a constant, and it can be expressed as:

Under the prerequisite of small-signal modulation (m (t)＜＜1), formula (11) substitution formula (9) can be got:

(12)

Under the prerequisite of small-signal modulation, can know by Bessel function character shown in Figure 1: J ₀Can be approximately constant 1, and J ₁Be linear function, promptly

Wherein, k ₁Be near the slope of single order Bessel function zero point,

Be the phase modulation (PM) coefficient,

Formula (13) substitution formula (12) can be got,

Suppose to use the polarization dispersion device to realize real-time chromatic dispersion Fourier transform, promptly do not have the deformation of the microwave pulse envelope that polarization mode dispersion causes.If the outgoing femto-second laser pulse is Gauss pulse, then i ₁(t) still be Gaussian distribution, note i ₁(t) Fourier transform is I (ω), and then the Fourier transform of formula (14) is:

E(ω)＝A _cδ(ω _c)+A _cK{I[ω-(ω _c+ω _m)]+(-1)I[ω-(ω _c-ω _m)]} (15)

Wherein, the phase place of two sidebands of (1) expression is opposite.Can be known by formula (15): the frequency spectrum of phase-modulation wave is made up of three frequency contents.Wherein, first is carrier component; Second and third is two sidebands that produce because of modulation.

So, phase-modulator output spectrum strength function is:

I(ω)＝A _c ²δ(ω _c)+A _c ²K ²{I ²[ω-(ω _c+ω _m)]+I ²[ω-(ω _c-ω _m)]} (16)

Fig. 4 is that the present invention uses edge method to measure the schematic diagram of sideband centre frequency, and is as shown in Figure 4, if carrier frequency is arranged on intensity transfer function T ₁Minimum point (ω) (is T ₂Peak (ω)), then two sideband signals are symmetrical distribution on transmittance function.

Note frequency discriminator tandem fibre optic interferometer is respectively T from the intensity transfer function of its fibre optic polarizing beam splitter (PBS) two-port output ₁(ω) and T ₂(ω), have spectral intensity so and be distributed as I ²Signal (ω) is after through said tandem fibre optic interferometer, and the transmittance function of two-port output is defined as by convolution respectively:

${\tilde{T}}_1\left(\mathrm{\ω}\right)=T_1\left(\mathrm{\ω}\right)*I^2\left(\mathrm{\ω}\right)---\left(17\right)$

${\tilde{T}}_2\left(\mathrm{\ω}\right)=T_2\left(\mathrm{\ω}\right)*I^2\left(\mathrm{\ω}\right)---\left(18\right)$

Then, consider the symmetry of spectrum, the signal intensity of two output terminals of PBS is respectively

$I_1={A_c}^2{K}^2[{\tilde{T}}_1({\mathrm{\ω}}_c+{\mathrm{\ω}}_m)+{\tilde{T}}_1({\mathrm{\ω}}_c-{\mathrm{\ω}}_m)]={{2A}_c}^2{K}^2{\tilde{T}}_1({\mathrm{\ω}}_c+{\mathrm{\ω}}_m)---\left(19\right)$

$I_2={A_{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="HDA00002078722000011.png,HDA00002078722000032.png"\; state="\{\{state\}\}">c</figure-callout>}}}^2+{A_c}^2{K}^2[{\tilde{T}}_2({\mathrm{\&omega;}}_c+{\mathrm{\&omega;}}_m)+{\tilde{T}}_2({\mathrm{\&omega;}}_c-{\mathrm{\&omega;}}_m)]={A_{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="HDA00002078722000011.png,HDA00002078722000032.png"\; state="\{\{state\}\}">c</figure-callout>}}}^2+{{2A}_c}^2{K}^2{\tilde{T}}_2({\mathrm{\&omega;}}_c+{\mathrm{\&omega;}}_m)---\left(20\right)$

Be divided by by (19) and (20) and obtain:

$R_{12}\left({\mathrm{\&omega;}}_m\right)=\frac{I_1}{I_2}=\frac{2K^2{\tilde{T}}_1({\mathrm{\&omega;}}_c+{\mathrm{\&omega;}}_m)}{1+2K^2{\tilde{T}}_2({\mathrm{\&omega;}}_c+{\mathrm{\&omega;}}_m)}---\left(21\right)$

Wherein, K is the constant of introducing in the formula (13).Can know by formula (21): R ₁₂(ω _m) be ω _mMonotonic quantity (ω here _m=τ/β ₂L).In the experiment through measuring the ratio R of two paths of signals intensity ₁₂(ω _m), the ratio of the signal strength values of the said two paths of signals that illustrates according to formula (21) and the frequencies omega of said microwave pulse frequency signal _mBetween relation, just can find the solution and obtain ω _m, and ω _mBe microwave pulse frequency of the presently claimed invention.

Fig. 5 is the femtosecond range laser radar real time data measuring system structural drawing that the present invention is based on real-time chromatic dispersion Fourier transform and microwave photon, and as shown in Figure 5, the inner structure of femtosecond range laser radar of the present invention and workflow are:

At first; The light source 12 emission laser pulses of femtosecond range laser radar; After the shoot laser pulse gets into the Mach-Zehnder interferometer; One tunnel process fiber circulators, 16 backs are surveyed the detection of a target by 13 outgoing of fiber optic collimator mirror, and the said detection of a target is a loudspeaker 14 that is driven by AWG 15; Light is through optical time delay unit 18 as a reference on another road, and said optical time delay unit 18 is used for regulating the time-delay between direct impulse and the reference pulse; At the exit end of Mach-Zehnder interferometer, use the optical fiber polarizer 20 that reference light and direct impulse light are interfered.Then, two arms of Mach-Zehnder interferometer use Polarization Controller 17,19 to regulate the visibility of interference fringe respectively.

Then, use two volume dispersion compensating fibers 21,23 that the interference signal of the said optical fiber polarizer 20 outputs is fully launched on time domain.In order to guarantee the signal to noise ratio (S/N ratio) of signal, use the amplifying signal of EDFA Erbium-Doped Fiber Amplifier EDFA1 22 and EDFA2 24 difference relaying dispersion compensating fibers 21,23.At last, the frequency domain interference fringe of femtosecond range laser radar output is received by spectrometer 25.

Next the generation flow process that more than belongs to time domain microwave pulse frequency signal is the flow process that the present invention measures for said time domain microwave pulse frequency signal in real time.

The time domain microwave pulse frequency signal of femtosecond range laser radar output; After photodetector 26 receptions; Get into BPF. 1 and carry out filtering; Use microwave amplifier 2 that it is amplified then, the signal after the amplification is as modulation signal input optical phase modulator 4, and the signal of single-frequency continuous light laser instrument 3 outputs is also imported optical phase modulator 4 as carrier wave and carried out phase modulation (PM); Use of the frequency displacement of tandem fibre optic interferometer then as frequency discriminator detected carrier first sideband signals; Said tandem fibre optic interferometer is made up of Polarization Controller 5, polarization maintaining optical fibre 6, Polarization Controller 7 and fibre optic polarizing beam splitter 8, and the signal of the said frequency discriminator of process gets into photodetector 9,10 respectively and measures, and the signal input oscillograph 11 that measures shows.

The frequency of the microwave pulse frequency signal of detector 26 outputs can be tried to achieve in the signal strength values of two output terminals of the PBS in the said frequency discriminator that measures according to said photodetector 9,10 and formula (13), (16), (17), (18), (21), can reappear the signal of femtosecond range laser radar emission.

The present invention is in the femtosecond range laser radar based on real-time chromatic dispersion Fourier transform, and range information is converted into the frequency information (microwave pulse frequency) of time domain interference fringe.Through modulation and the edge Frequency discrimination technology to the single-frequency continuous light, microwave photon is learned disposal route and effectively the frequency measurement of high-frequency microwave pulse signal is converted into optic frequency detecting.

It is long-pending that this method has very wide " time-bandwidth "; Strong anti-electromagnetic interference capability and superfast SF (the 100GHz order of magnitude is higher than the response frequency of general photodetector) have really realized the real time data inverting in the femtosecond laser radar.And, under this method, the microwave signal proportion of goods damageds that are processed very low the frequency-independent of microwave signal (and with).

Above-described specific embodiment; The object of the invention, technical scheme and beneficial effect have been carried out further explain, and institute it should be understood that the above is merely specific embodiment of the present invention; Be not limited to the present invention; All within spirit of the present invention and principle, any modification of being made, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (15)

1. femtosecond range laser radar real time data measuring method of learning based on microwave photon is characterized in that this method may further comprise the steps:

Step 1, the distance signal that will measure based on the femtosecond range laser radar of real-time chromatic dispersion Fourier transform is converted into the frequency signal of time domain interference fringe, i.e. microwave pulse frequency signal;

Step 2 is amplified said microwave pulse frequency signal through using microwave amplifier after the band-pass filter;

Step 3 as modulation signal, is carried out phase modulation (PM) to carrier wave with the microwave pulse frequency signal after amplifying, and wherein, the frequency of said microwave pulse frequency signal is corresponding to the centre frequency of said carrier wave first sideband signals;

Step 4, through Optical Frequency Discriminator, use edge method detects the frequency of said carrier wave first sideband signals, can obtain the frequency of said microwave pulse frequency signal.

2. measuring method according to claim 1 is characterized in that, the logical scope of the band of said BPF. is 1-40GHz.

3. measuring method according to claim 1 is characterized in that, said carrier wave adopts single-frequency continuous light laser instrument to produce.

4. measuring method according to claim 1 is characterized in that, said step 4 further is: through detecting the variation of said carrier wave first sideband signals transmitance on frequency discriminator, the change of frequency of coming said carrier wave first sideband signals of inverting.

5. measuring method according to claim 1 is characterized in that, said Optical Frequency Discriminator is the tandem fibre optic interferometer.

6. measuring method according to claim 5 is characterized in that, said step 4 further may further comprise the steps:

Step 41 measures the ratio R of the two paths of signals signal intensity of said tandem fibre optic interferometer output ₁₂(ω _m);

Step 42 is according to the frequencies omega of the ratio and the said microwave pulse frequency signal of said signal intensity _mBetween relation try to achieve the frequencies omega of said microwave pulse frequency signal _m

7. measuring method according to claim 6 is characterized in that, the frequencies omega of the ratio of said signal intensity and said microwave pulse frequency signal _mBetween relation be:

$R_{12}\left({\mathrm{\&omega;}}_m\right)=\frac{2K^2{\tilde{T}}_1({\mathrm{\&omega;}}_c+{\mathrm{\&omega;}}_m)}{1+2K^2{\tilde{T}}_2({\mathrm{\&omega;}}_c+{\mathrm{\&omega;}}_m)},$

Wherein,

k ₁Be near the slope of single order Bessel function zero point,

Be the index of modulation,

Be respectively the transmittance function of the two paths of signals of said tandem fibre optic interferometer output,

Phasing degree for carrier wave.

8. measuring method according to claim 7; It is characterized in that said transmittance function

is respectively:

${\tilde{T}}_1\left(\mathrm{\&omega;}\right)=T_1\left(\mathrm{\&omega;}\right)*I^2\left(\mathrm{\&omega;}\right),$ ${\tilde{T}}_2\left(\mathrm{\&omega;}\right)=T_2\left(\mathrm{\&omega;}\right)*I^2\left(\mathrm{\&omega;}\right),$

Wherein, T ₁(ω), T ₂(ω) be respectively the intensity transfer function that said tandem fibre optic interferometer two-way is exported; I ²Be that the spectral intensity that is input to the signal of said tandem fibre optic interferometer distributes (ω).

9. the measurement mechanism of a femtosecond range laser radar real time data of learning based on microwave photon; It is characterized in that; This measurement mechanism comprises: BPF. (1), microwave amplifier (2), single-frequency continuous light laser instrument (3), optical phase modulator (4), frequency discriminator, detector (9) and photodetector (10), wherein:

Said BPF. (1) is used for the time domain microwave pulse frequency signal of the femtosecond range laser radar that is converted to is carried out filtering;

Said microwave amplifier (2) is used for amplifying through filtered signal;

Said single-frequency continuous light laser instrument (3) is used to produce carrier signal;

Said optical phase modulator (4) is used for as modulation signal said carrier signal being carried out phase modulation (PM) with the signal after amplifying through said microwave amplifier (2);

Said frequency discriminator is used to detect the frequency displacement of the carrier signal that obtains through said phase modulation (PM);

Said detector (9) and photodetector (10) are used to receive the two paths of signals of said frequency discriminator output, and measure the signal strength values of this two paths of signals.

10. measurement mechanism according to claim 9 is characterized in that, said frequency discriminator is the tandem fibre optic interferometer.

11. measurement mechanism according to claim 8 is characterized in that, said tandem fibre optic interferometer comprises Polarization Controller (5), polarization maintaining optical fibre (6), Polarization Controller (7) and fibre optic polarizing beam splitter PBS (8) successively.

12. measurement mechanism according to claim 7 is characterized in that, said measurement mechanism also comprises oscillograph (11), is used for reception, shows and handles the signal that said detector (9) and photodetector (10) receive.

13. measurement mechanism according to claim 7 is characterized in that, according to the ratio of the signal strength values of said two paths of signals and the frequencies omega of said microwave pulse frequency signal _mBetween relation try to achieve the frequencies omega of said microwave pulse frequency signal _m

14. measurement mechanism according to claim 13 is characterized in that, the frequencies omega of the ratio of said signal strength values and said microwave pulse frequency signal _mBetween relation be:

$R_{12}\left({\mathrm{\&omega;}}_m\right)=\frac{2K^2{\tilde{T}}_1({\mathrm{\&omega;}}_c+{\mathrm{\&omega;}}_m)}{1+2K^2{\tilde{T}}_2({\mathrm{\&omega;}}_c+{\mathrm{\&omega;}}_m)},$

Wherein,

k ₁Be near the slope of single order Bessel function zero point, Be the index of modulation,

Be respectively the transmittance function of the two paths of signals of said frequency discriminator output,

Phasing degree for carrier wave.

15. measuring method according to claim 14; It is characterized in that said transmittance function

is respectively:

${\tilde{T}}_1\left(\mathrm{\&omega;}\right)=T_1\left(\mathrm{\&omega;}\right)*I^2\left(\mathrm{\&omega;}\right),$ ${\tilde{T}}_2\left(\mathrm{\&omega;}\right)=T_2\left(\mathrm{\&omega;}\right)*I^2\left(\mathrm{\&omega;}\right),$

Wherein, T ₁(ω), T ₂(ω) be respectively the intensity transfer function that said frequency discriminator two-way is exported; I ²Be that the spectral intensity that is input to the signal of said frequency discriminator distributes (ω).

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