CN105136175B - A kind of phase sensitive optical time domain reflection system based on self-mixing technology - Google Patents
A kind of phase sensitive optical time domain reflection system based on self-mixing technology Download PDFInfo
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- CN105136175B CN105136175B CN201510446560.4A CN201510446560A CN105136175B CN 105136175 B CN105136175 B CN 105136175B CN 201510446560 A CN201510446560 A CN 201510446560A CN 105136175 B CN105136175 B CN 105136175B
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Abstract
The invention discloses a kind of phase sensitive optical time domain reflection system based on self-mixing technology.Demodulated two parts by light path detection and circuit and constituted；Optical routing narrow linewidth laser (1), photo-coupler (2), acousto-optic degree modulator (3), impulse function generator (4), circulator (5), optical fiber (6), Polarization Controller (7) composition；Circuit is by electric bandpass filter (10), low noise acoustoelectric amplipher (11), power splitter (12), frequency mixer (13), low pass filter (14) composition；Demodulation to modulated signal can not only be realized using the such simple structure of self-mixing, moreover it is possible to eliminate due to demodulating inconvenience caused by the frequency drift of local optical signal.In the phase sensitive optical time domain reflection technology system using coherent detection mode, the frequency drift of local light is the problem that must take into consideration.The present invention eliminates the influence that local light frequency drift is brought well.Present apparatus working stability, position and the frequency of vibration accurate can be measured in multiple measurement.
Description
Technical field
The present invention relates to Distributed Optical Fiber Sensing Techniques --- the demodulation skill in phase sensitive optical time domain reflection technology
Art, is specifically applied in a kind of phase sensitive optical time domain reflection system, forms a kind of phase based on self-mixing technology
The sensitive optical time domain reflection system in position.
Background technology
Distributed Optical Fiber Sensing Techniques in recent years, with the high speed development of oil-gas pipeline, high ferro, heavy construction etc., its
Safety is increasingly paid close attention to by all circles, and Distributed Optical Fiber Sensing Techniques are due to itself substantial amounts of advantage so that it turns into length
The key technology of external information perception is carried out under distance, adverse circumstances.And the optical time domain reflection technology of phase sensitive is exactly distributed
A member in formula optical fiber sensing technology big family, its major function is, for measuring external disturbance, invasion etc., it can not only to be entered
Row positioning can also measure its forcing frequency.Although the technology is in the stage of comparative maturity, its Detection Techniques master at present
There are two classes：1st, direct detection；The Detection Techniques are very high to the sensitivity requirement of photodetector, and sensing scope it is general compared with
It is small.2nd, coherent detection；The Detection Techniques are the Detection Techniques of current main flow, and the technology can realize farther distance sensing, and right
Detector sensitivity requirement is not especially high.But the technology electric signal needs once to be demodulated again, mainly there is two classes at present
Demodulation techniques above electricity are applied and the technology：A, coherent demodulation；B, quadrature demodulation；Two kinds of demodulation techniques are required for producing one
Local signal, while this local signal can not follow the frequency of the broadband signal caused by local optical signal frequency drift to float
Move, therefore can not modulate signals into out well in demodulation.
The content of the invention
In view of deficiency of the prior art on to phase demodulating, it is an object of the invention to provide the simple and effective demodulation of one kind
Method demodulates the disturbing signal being modulated on light phase to come.Phase sensitive optical time domain reflection system based on self-mixing mode
System, using the mode solution dim signal of coherent detection, improves distance sensing.
The purpose of the present invention is proposed and realized based on following analysis and scheme：
A kind of phase sensitive optical time domain reflection system based on self-mixing technology, light path is carried out using flashlight and local light
Coherent demodulation, the circuit then demodulated signal by the way of self-mixing, using frequency mixer by two paths of signals be mixed just can by the external world plus
The signal being loaded on optical fiber, which is demodulated, to be come, and its concrete structure is：
The continuous light that narrow linewidth laser 1 is exported is divided into two-way, a route and the phase of impulse generator 4 after photo-coupler 2
Acousto-optic modulator 3 even is modulated to be injected into sensor fibre 6 through circulator 5 after pulsed light；Another road passes through Polarization Controller 7
It is connected with coupler 8；The rear orientation light that pulsed light is produced in transmitting procedure in a fiber is defeated from another port by circulator 5
Go out, the scattered light of output synthesizes light beam with local light at coupler 8, then carry out beat frequency, beat frequency letter through balanced detector 9
The frequency displacement that number frequency is introduced by acousto-optic modulator 3 determines that beat signal is filtered by electric bandpass filter 10, low noise amplifier 11
After amplification, the electric signal of balance photodetector output is divided into two-way, i.e., by work(point than being 50:50 12 points of power splitter is identical
Two signals, then be demodulated with frequency mixer 13, eventually pass and gathered simultaneously with data collecting card 15 after low pass filter 14
Handled with data processor 16.
In apparatus of the present invention, because laser has a line width, and local light has a frequency drift, therefore the electricity after beat frequency
Signal is a broadband signal, is represented by：S (t)=A cos (ω1t+φ1)+B cos(ω2t+φ2)+…+N cos(ωnt
+φn).Analyzed since two frequency components, S1(t)=A cos (ω1t+φ1)+B cos(ω2t+φ2), then by certainly mixed
Signal S can be obtained by being become after frequency by low pass filter1 2(t)=A2/2+B2/2+AB cos[(ω1-ω2)t+(φ1-
φ2)]；Because the intensity of spectrum different frequency is different, in Lorentzian type；Therefore the electricity spectrum after beat frequency is equally in Lorentzian type, then
For the S at a certain moment2(t), frequency is a variable, then all frequency letters in the position can be obtained by the integration to frequency
Number superposition value, and integrate final result will determine that the i.e. change of phase will reflect by the initial phase of cosine function
To above integrated value, therefore the information of phase can be obtained by solving integrated value, and integral process only need to be used it is hard
The bandwidth that part equipment can respond electric signal just can be realized, therefore can directly obtain its demodulation result.
By the way of self-mixing, because local oscillation signal uses itself, then local signal frequency when being avoided that mixing
With the unmatched problem of radio frequency signal frequency.Present apparatus working stability, vibration accurate can be measured in multiple measurement
Position and frequency.
In the present invention, the RF produced using balance photodetector beat frequency is divided into two and then is mixed, and is mixed it
The signal after demodulation just can be got by low pass filter again afterwards, then disturbance just can be demodulated by simple data processing
Position and frequency.This self-mixing demodulation techniques, it is simple in construction, it is not necessary to produce a stable local signal, and can disappear
Except the bad phenomenon of the demodulation effect caused by broadband signal caused by local optical signal frequency drift is unstable, effect is demodulated
Very well.
Brief description of the drawings：
Fig. 1 is system construction drawing of the invention；
Fig. 2 is the vibration positioning of loading vibration measurement and frequency effects figure on 10Km optical fiber, wherein：A) it is auditory localization cues
Figure；B) it is vibration position time-domain curve figure；C is rumble spectrum figure.
Embodiment
The invention will be further described below in conjunction with the accompanying drawings.
Fig. 1 is a kind of phase sensitive optical time domain reflection system construction drawing based on self-mixing mode of the invention, such as figure institute
Show, system is made up of light path and circuit two parts.The continuous light that narrow linewidth laser 1 is exported is modulated to arteries and veins through acousto-optic modulator 3
Sensor fibre 6 is injected into through circulator 5, the rear orientation light that pulsed light is produced in transmitting procedure in a fiber passes through after washing off
Circulator 5 is exported from another port, and the scattered light of output synthesizes light beam with local light at coupler 8, is then visited through balance
Survey device 9 and carry out beat frequency, the frequency displacement that beat signal frequency is introduced by acousto-optic modulator 3 is determined, after beat signal amplifies after filtering,
By work(point than being 50:50 12 points of power splitter is two signals of identical, then is demodulated with frequency mixer 13, eventually passes low pass
Gathered and handled with data processor 16 with data collecting card 15 after filtering and obtain end product.
During implementation, the balance electrical domain band of photodetector 9 is wider than the frequency shift value of the introducing of acousto-optic modulator 3.Electric bandpass filtering
The centre frequency of device 10 is identical with the frequency displacement that acousto-optic modulator 3 is introduced, the frequency that bandwidth is introduced with the frequency drift of super-narrow line width laser 1
Shifting value is identical.The power ratio of electric power splitter 12 is 50:50.The RF ends of electric frequency mixer 13 and the input of LO ends are drawn with acousto-optic modulator 3
The frequency shift value entered is identical, and IF ends are bandwidth values of the DC to electric bandpass filter 10.
Fig. 2 carries out vibration-testing using 10Km optical fiber as shown in the figure to test design sketch using apparatus of the present invention, using certainly
Mixing demodulation mode, which is demodulated, obtains result, and a figures are vibration auditory localization cues, and b figures are test gained vibration time-domain curve, c figures
For the spectrogram of vibration signal.It can see that from test result above, can be effectively by the external world using self-mixing demodulation mode
Modulated signal is demodulated.
The beneficial effects of the invention are as follows：
1. the device is applied to the phase sensitive optical time domain reflection system using coherent detection mode.Demodulated using self-mixing
Mode, advantage is：(1) it can be realized using simple experimental provision and structure and the signal being modulated in phase is solved
Adjust；(2) demodulation effect is not great curiosity to ask all sorts of questions caused by eliminating the mismatch of the caused local oscillation signal of laser frequency drift and beat signal
Topic.Present apparatus working stability, position and the frequency of vibration accurate can be measured in multiple measurement.
Claims (1)
1. a kind of phase sensitive optical time domain reflection system based on self-mixing technology, it is characterised in that：Light path using flashlight and
Local light carries out coherent demodulation, the circuit then demodulated signal using self-mixing by the way of, using frequency mixer by two paths of signals mixing just
The signal that the external world can be carried on optical fiber, which is demodulated, to be come, and its concrete structure is：
The continuous light of narrow linewidth laser (1) output is divided into two-way, a route and impulse generator (4) after photo-coupler (2)
Connected acousto-optic modulator (3) is modulated to be injected into sensor fibre (6) through circulator (5) after pulsed light；Another road passes through inclined
The controller (7) that shakes is connected with coupler (8)；The rear orientation light that pulsed light is produced in transmitting procedure in a fiber passes through circulator
(5) exported from another port, the scattered light of output synthesizes light beam with local light at coupler (8) place, then through balance detection
Device (9) carries out beat frequency, and the frequency displacement that beat signal frequency is introduced by acousto-optic modulator (3) is determined, beat signal is by electric band logical filter
After ripple device (10), low noise amplifier (11) filter and amplification, the electric signal of balanced detector (9) output is divided into two-way, i.e., by work(point
Than for 50:50 power splitter (12) is divided into two signals of identical, then electricity consumption frequency mixer (13) is realized to being modulated in phase
Signal is demodulated, and is eventually passed after low pass filter (14) with data collecting card (15) collection and with data processor (16)
Processing；
Balanced detector (9) electrical domain band is wider than the frequency shift value of acousto-optic modulator (3) introducing；
Electric bandpass filter (10) centre frequency is identical with the frequency displacement that acousto-optic modulator (3) is introduced, bandwidth and narrow linewidth laser
(1) frequency shift value that frequency drift is introduced is identical；
Electric frequency mixer (13) RF ends and LO ends input is identical with the frequency shift value that acousto-optic modulator (3) is introduced, and IF ends are DC to electric band
The bandwidth value of bandpass filter (10).
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Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106500742B (en) * | 2016-12-30 | 2018-08-28 | 中国电子科技集团公司第三十四研究所 | A kind of phase sensitive optical time domain reflectometer phase demodulating system and phase demodulating method |
| CN107560644B (en) * | 2017-07-20 | 2020-01-14 | 全球能源互联网研究院 | Distributed optical fiber sensing device based on signal multiplexing perception and demodulation |
| CN107957276B (en) * | 2018-01-05 | 2019-07-12 | 南京大学 | Phase sensitive optical time domain reflectometer and its measurement method based on frequency-drift compensation |
| CN108759879B (en) * | 2018-04-26 | 2019-11-26 | 浙江大学 | A kind of wavelength resolver based on grating sensor |
| CN108562311B (en) * | 2018-04-26 | 2019-08-20 | 浙江大学 | A kind of location resolution device of photosensor array |
| CN109412699B (en) * | 2018-11-28 | 2020-11-17 | 武汉邮电科学研究院有限公司 | Pulse generation method and device, coherent phase sensitive time domain reflection method and system |
| CN110044401B (en) * | 2019-05-07 | 2020-04-28 | 电子科技大学 | Signal demodulation method and system of optical fiber sensor |
| CN112985573A (en) * | 2019-12-13 | 2021-06-18 | 挚感(苏州)光子科技有限公司 | Detection method and device |
| CN111366232A (en) * | 2020-04-08 | 2020-07-03 | 中国科学院长春光学精密机械与物理研究所 | All-fiber pulse laser Doppler vibrometer and signal processing method thereof |
| CN113447112A (en) * | 2021-06-18 | 2021-09-28 | 天津大学 | Reflected light-based high-frequency vibration sensing system and high-frequency signal demodulation method |
| WO2023205956A1 (en) * | 2022-04-24 | 2023-11-02 | 华为技术有限公司 | Receiver, rfid reading device, and signal receiving method |
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