CN110470251A - A kind of optical fibre length measurement method based on optical-electronic oscillator - Google Patents
A kind of optical fibre length measurement method based on optical-electronic oscillator Download PDFInfo
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- CN110470251A CN110470251A CN201910819037.XA CN201910819037A CN110470251A CN 110470251 A CN110470251 A CN 110470251A CN 201910819037 A CN201910819037 A CN 201910819037A CN 110470251 A CN110470251 A CN 110470251A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B15/00—Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons
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Abstract
The invention discloses a kind of optical fibre length measurement methods based on optical-electronic oscillator, the laser issues direct current light and is modulated by the intensity modulator, when not accessing testing fiber, modulation light passes through photodetector, convert optical signals into electric signal, electric signal feeds back to intensity modulator by amplification, filtering, by the microwave signal filtered out, forms optoelectronic oscillation circuit；Microwave source output and microwave signal similar in OEO output signal centre frequency, pass through the microwave signal of the exportable MHz magnitude of frequency mixer, to by frequency meter accurately read frequency, fundamental frequency is roughly calculated, by series of computation, then it is long to calculate OEO chamber at this time using the long relationship with fundamental frequency of OEO chamber for available accurate fundamental frequency；When accessing testing fiber, this process is repeated, the chamber that can calculate OEO is long, and the long difference of the two chamber is testing fiber length.The method is affected by temperature, measurement accuracy is in cm magnitude, and system structure is simple, easily operated when optical fiber is km magnitude.
Description
Technical field
The present invention relates to a kind of optical fibre length measurement methods based on optical-electronic oscillator.
Background technique
Optical fiber is due to bandwidth, conduction loss is low, light-weight, strong antijamming capability, functional reliability are high, can be used as it is long away from
From information transmitting etc. reasons, become modern communications and information transmission best medium.It is swift and violent with Fibre Optical Communication Technology
Development, in some high-precision optical devices, the requirement to the precision of fiber lengths is very high, between optical fiber when generating opposite
Prolong, output signal will be just distorted due to optical-fiber time-delay either to be weakened.Also, during engineering and test, to optical fiber
Length, which measures, to be very important, and the precise measurement of fiber lengths has very the development, production and maintenance of optical fiber
Important meaning, so, it is all particularly significant in fiber optic communication and optical fiber sensing system accurately to measure fiber lengths.
Currently, measurement fiber lengths method mainly have: optical time domain reflectometry (OTDR), probe beam deflation method (OFDR),
Full optical fiber interference method, mode locking method, femtosecond pulse method, modulation phase shift method, laser phase method etc..
OTDR method is to carry out linear measure longimetry to optical fiber based on Rayleigh scattering principle, and the scattered signal of optical fiber itself is weaker,
Requirement in this approach for light source and detector it is relatively high, lead to higher cost；And there are measurement blind area, In for the method
In the case that optical fiber is shorter, it cannot be measured, measurement accuracy is m magnitude.OFDR method is based on relevant testing principle pair
Optical fiber carries out linear measure longimetry, and the dynamic range of measurement is big, and measurement accuracy is mm magnitude, however, to ensure that coherence, to light source
It is required that it is relatively high, and due to temperature, it will lead to light source frequency sweep nonlinear problem.
In recent years, the research about optical fiber length measuring has a great development.2002, Jia Bo et al. was using entirely
Fiber optic interferometric system realizes the measurement to fiber lengths, completely solves the blind zone problem of OTDR method.This method measurement result
It is of slight difference with OTDR method measurement result, and measurement range is smaller, and measurement accuracy is by interference fringe counting and reference optical fiber
Effect length.
2007, Hu Yanli et al. proposed a kind of optical fibre length measurement method based on passive mode-locking principle --- mode locking
Method measures fiber lengths to this long directly proportional relationship of chamber using the mode-locked laser stable pulse period.This method measurement
Range is larger, and stability is good, but higher cost, is unable to measure its length when fiber lengths are less than 500m.2013, Jia Yu
East et al. is based on double-colored double frequency space distance measurement method, using optical fiber femtosecond laser, devises all -fiber coupling femtosecond fiber
Length measurement method.For this method measurement range up to 50km, measurement accuracy is cm magnitude.
2013, Ye Quanyi et al. proposed a kind of method that fiber lengths are measured using phase-modulation optical link.It should
Method be suitable in, the measurement of the precise length of short fiber, measurement accuracy is mm magnitude；If measuring longer optical fiber, for
The requirement of reference optical fiber and light source is relatively high, higher cost.2016, Zhu Xingbang et al. utilized integrated vector network analysis
The high speed modulated signal simultaneous techniques and high-frequency signal phase difference measurement Technology design of instrument simultaneously have developed single-mode optical fiber length measurement
Device, precision is up to μm magnitude when measuring short fiber, and precision is up to m magnitude when measuring long optical fibers, but the device is by temperature shadow
Sound is bigger, will affect accuracy of measurement.
2017, Xu Ziyan et al. proposed that laser phase method measures fiber lengths, using the light wave of intensity modulated tested
Proportionate relationship between the phase shift generated in optical fiber transmission process and tested optical fiber length measures fiber lengths, and this method is suitable for
Short fiber is measured, measurement range is smaller, at low cost, but stability is poor, and if do not know the coarse value of tested optical fiber, measure essence
Degree can reduce.
Summary of the invention
For the prior art, the present invention provides a kind of optical fibre length measurement methods based on optical-electronic oscillator, solve
Existing fiber length measurement technique is by measurement scope limitation, and the problems such as stability is poor, system structure of the invention is simply easily realized,
The system that can be used as a kind of stable measurement fiber lengths.The present invention is not limited by measurement range, more importantly logical
Cross the long relational expression with frequency interval of OEO chamber, the length of tested optical fiber can be calculated, and cost is relatively low, stablize compared with
It is high.
In order to solve the above-mentioned technical problem, a kind of optical fiber length measuring side based on optical-electronic oscillator proposed by the present invention
Method, including following optical device and electronic device: laser, intensity modulator, photodetector, electric amplifier, band logical filter
Wave device, frequency mixer, microwave source and frequency meter；The direct current light that the laser issues is modulated by the intensity modulator,
Subsequently into the photodetector, electric signal is converted optical signals into, electric signal is amplified by electric amplifier, using band logical
The microwave signal filtered out is fed back to intensity modulator as modulated signal by filter, to form optoelectronic oscillation circuit；
Follow the steps below optical fiber length measuring:
Step 1: adjust the bias voltage of the intensity modulator, the optoelectronic oscillation circuit is enable to succeed starting of oscillation, it is defeated
Stable microwave signal out, the centre frequency of the microwave signal are fhm；
Step 2: being f by the centre frequency of microwave source outputms=fhmThe microwave signal of ± 100MHz and the photoelectricity shake
Swing the microwave signal f of the output in circuithmIt is connected on the frequency mixer, at this point, the frequency meter measures the microwave after mixing
The centre frequency of signal is flm；
Step 3: repeating step 2 n times, show that the centre frequency of the microwave signal after n times mixing is flm1、flm2、
flm3、……、flmn, according to formula fhm=fms+flm, find out the microwave letter of the corresponding optoelectronic oscillation circuit output of measurement every time
Number centre frequency fhm1、fhm2、fhm3、……、fhmn；
Step 4: the mode spacing of the microwave signal in the optoelectronic oscillation circuit | fhm2–fhm1|、|fhm4–fhm3|、……、|
fhmn–fhmn-1| greatest common divisor be the optoelectronic oscillation circuit fundamental frequency coarse value fb *；And then show that the optoelectronic oscillation returns
The oscillation mode number on roadWherein,For round operation；The fundamental frequency in the electric oscillation circuit
Step 5: the long L of the chamber for finding out optoelectronic oscillation circuit is c/nfb, wherein n be this moment at a temperature of optical fiber refractive index,
C is the light velocity；Including following two kinds of situations:
1) in the case where not accessing testing fiber, the chamber length in optoelectronic oscillation circuit is denoted as L1；Testing fiber is connected to
Between the intensity modulator and the photodetector, return step two.
2) in the case where accessing testing fiber, the chamber length in optoelectronic oscillation circuit is denoted as L2；It is long to finally obtain testing fiber
Spend LFiber=L2-L1。
Compared with prior art, the beneficial effects of the present invention are:
Due to can produce the microwave signal for stablizing output present invention utilizes optical-electronic oscillator principle, signal quality is big
Big to improve, the requirement to light source and optical device substantially reduces, and easily controllable and adjusting, and structure is simple, and cost is relatively low, surely
It is qualitative higher；Secondly by frequency mixer, microwave source, frequency meter and OEO chamber length and fundamental frequency relational expression fb=c/ (nL), no matter
Optical fiber length can calculate the length of testing fiber, not limited by measurement range.
Detailed description of the invention
Fig. 1 is that the present invention is based on the optical fibre length measurement method schematic diagrames of optical-electronic oscillator.
In figure: 1- laser, 2- intensity modulator, 3- testing fiber, 4- photodetector, 5- electric amplifier, 6- band logical
Filter, 7- frequency mixer, 8- microwave source, 9- frequency meter.
Specific embodiment
With reference to the accompanying drawing and specific embodiment the present invention is described further, but following embodiments are absolutely not to this hair
It is bright to have any restrictions.
Mentality of designing of the invention is, since optoelectronic oscillation circuit (OEO) can export stable microwave signal, by mixed
The lower frequency microwave signals of frequency device output can accurately be read its frequency by frequency meter, so as to roughly obtain fundamental frequency fb *；
By series of computation, available accurate fundamental frequency fb, then OEO can be calculated using the long relationship with fundamental frequency of OEO chamber
Chamber it is long, do not access the long L of chamber of testing fiber with the corresponding OEO of access testing fiber by measuring1And L2Both, obtain
The long difference Δ L=L of chamber2-L1, further according to the refractive index n of optical fiber at a temperature of this moment, testing fiber length can be calculated.
As shown in Figure 1, a kind of optical fibre length measurement method based on optical-electronic oscillator proposed by the present invention, including following
Optical device and electronic device: laser 1, intensity modulator 2, photodetector 4, electric amplifier 5, bandpass filter 6, mixing
Device 7, microwave source 8 and frequency meter 9.
The direct current light that the laser 1 issues is modulated by the intensity modulator 2, when not accessing testing fiber
When, subsequently into the photodetector 4, electric signal is converted optical signals into, electric signal is amplified by electric amplifier 5, then is passed through
The filtering of bandpass filter 6 is crossed, the microwave signal filtered out is fed back into intensity modulator 2 as modulated signal, to form photoelectricity
Oscillation circuit.
Testing fiber 3 is connect between intensity modulator 2 and electric explorer 4, the direct current light that the laser 1 issues is passed through
The intensity modulator 2 is modulated, and when accessing testing fiber, modulation light passes through one section of testing fiber 3, subsequently into described
Photodetector 4 converts optical signals into electric signal, and electric signal is amplified by electric amplifier 5, filters using bandpass filter 6
The microwave signal filtered out is fed back to intensity modulator 2 as modulated signal, to form optoelectronic oscillation circuit by wave.
The system is based on OEO principle, by the multiple process, the exportable stable microwave with frequency interval of OEO
Signal.The output of microwave source 8 can be exported with microwave signal similar in OEO output microwave signal centre frequency by frequency mixer 7
The microwave signal of lower frequency can be roughly calculated out to accurately calculate output frequency by frequency meter 9 by frequency meter
Fundamental frequency fb *, utilize the long relational expression f with before fundamental frequency of OEO chamberb=c/ (nL), it is available accurate by series of computation
Fundamental frequency fb, the chamber that then can finally calculate OEO is long, and it is corresponding with access testing fiber that measurement does not access testing fiber
The long L of the chamber of OEO1And L2, obtain the long difference Δ L=L of the two chamber2-L1, further according to the refractive index n of optical fiber at a temperature of this moment
Calculate testing fiber length.Specific step is as follows:
Step 1: adjust the bias voltage of the intensity modulator 2, the optoelectronic oscillation circuit is enable to succeed starting of oscillation,
Stable microwave signal is exported, the centre frequency of the microwave signal is fhm；
Step 2: the centre frequency f that microwave source 8 is exportedmsWith the microwave signal centre frequency f of OEO ring cavity outputhmPhase
Close frequency, i.e. fms=fhm± 100MHz, the microwave signal for then exporting microwave source 8 are defeated with the optoelectronic oscillation circuit
Microwave signal f outhmIt is connected on the frequency mixer 7, by the microwave signal of the exportable MHz magnitude of frequency mixer, at this point, the frequency
The centre frequency that rate meter 9 measures the microwave signal after mixing is flm, i.e., by frequency meter accurately read frequency, when frequency is low
0.01Hz is easily reached in the measurement accuracy of 100MHz, frequency meter.
Step 3: repeating step 2 n times, show that the centre frequency of the microwave signal after n times mixing is flm1、flm2、
flm3、……、flmn, according to formula fhm=fms+flm, find out the microwave letter of the corresponding optoelectronic oscillation circuit output of measurement every time
Number centre frequency fhm1、fhm2、fhm3、……、fhmn；
Step 4: the mode spacing of the microwave signal in the optoelectronic oscillation circuit | fhm2–fhm1|、|fhm4–fhm3|、……、|
fhmn–fhmn-1| greatest common divisor be the optoelectronic oscillation circuit fundamental frequency coarse value fb *, fundamental frequency fb *For adjacent starting of oscillation mode
Frequency interval, and then obtain the oscillation mode number in the optoelectronic oscillation circuitWherein,It is taken to round up
Whole operation；According to the high-order frequency of oscillation f acquiredhm1With oscillation mode number Nhm1Come the anti-accurate base for releasing the electric oscillation circuit
Frequently
Step 5: being c/nf according to the long long L of chamber for finding out optoelectronic oscillation circuit with mode hopping spaced relationship formula of OEO chamberb,
In, n be this moment at a temperature of optical fiber refractive index, c is the light velocity；Including following two kinds of situations:
1) in the case where not accessing testing fiber 3, the chamber length in optoelectronic oscillation circuit is denoted as L1；Testing fiber 3 is connected
Between the intensity modulator 2 and the photodetector 4, return step two.
2) in the case where accessing testing fiber 3, the chamber length in optoelectronic oscillation circuit is denoted as L2；The two is subjected to difference operation
Finally obtain testing fiber length LFiber=L2-L1。
Measurement method of the invention can calculate the length of testing fiber, and optical fiber is affected by temperature in km magnitude, measurement
Precision is in cm magnitude, and system structure is simple, and cost is relatively low, easily operated.
Although above in conjunction with attached drawing, invention has been described, and the invention is not limited to above-mentioned specific implementations
Mode, the above mentioned embodiment is only schematical, rather than restrictive, and those skilled in the art are at this
Under the enlightenment of invention, without deviating from the spirit of the invention, many variations can also be made, these belong to of the invention
Within protection.
Claims (1)
1. a kind of optical fibre length measurement method based on optical-electronic oscillator, which is characterized in that including following optical device and electricity
Sub- device: laser (1), intensity modulator (2), photodetector (4), electric amplifier (5), bandpass filter (6), frequency mixer
(7), microwave source (8) and frequency meter (9)；
The direct current light that the laser (1) issues is modulated by the intensity modulator (2), is visited subsequently into the photoelectricity
It surveys device (4), converts optical signals into electric signal, electric signal is amplified by electric amplifier (5), will using bandpass filter (6)
The microwave signal filtered out feeds back to intensity modulator (2) as modulated signal, to form optoelectronic oscillation circuit；
Follow the steps below optical fiber length measuring:
Step 1: adjust the bias voltage of the intensity modulator (2), the optoelectronic oscillation circuit is enable to succeed starting of oscillation, it is defeated
Stable microwave signal out, the centre frequency of the microwave signal are fhm；
Step 2: being f by the centre frequency of microwave source (8) outputms=fhmThe microwave signal of ± 100MHz and the optoelectronic oscillation
The microwave signal f of the output in circuithmIt is connected on the frequency mixer (7), at this point, the frequency meter (9) is measured after being mixed
The centre frequency of microwave signal is flm；
Step 3: repeating step 2 n times, show that the centre frequency of the microwave signal after n times mixing is flm1、flm2、
flm3、……、flmn, according to formula fhm=fms+flm, find out the microwave letter of the corresponding optoelectronic oscillation circuit output of measurement every time
Number centre frequency fhm1、fhm2、fhm3、……、fhmn；
Step 4: the mode spacing of the microwave signal in the optoelectronic oscillation circuit | fhm2–fhm1|、|fhm4–fhm3|、……、|fhmn–
fhmn-1| greatest common divisor be the optoelectronic oscillation circuit fundamental frequency coarse value fb *；And then obtain the optoelectronic oscillation circuit
Oscillation mode numberWherein,For round operation；The fundamental frequency in the electric oscillation circuit
Step 5: the long L of the chamber for finding out optoelectronic oscillation circuit is c/nfb, wherein n be this moment at a temperature of optical fiber refractive index, c is light
Speed；Including following two kinds of situations:
1) in the case where not accessing testing fiber (3), the chamber length in optoelectronic oscillation circuit is denoted as L1；Testing fiber (3) is connected to
Between the intensity modulator (2) and the photodetector (4), return step two.
2) in the case where accessing testing fiber (3), the chamber length in optoelectronic oscillation circuit is denoted as L2；Finally obtain testing fiber length
LFiber=L2-L1。
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113067644A (en) * | 2021-03-05 | 2021-07-02 | 北京邮电大学 | Bias voltage control device and system of modulator |
| CN116045817A (en) * | 2023-01-09 | 2023-05-02 | 天津大学 | Micro-displacement measuring device and method based on photoelectric oscillator |
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| CN102494617A (en) * | 2011-12-09 | 2012-06-13 | 华中科技大学 | Single mode fiber length measuring system |
| CN107342816A (en) * | 2017-06-28 | 2017-11-10 | 天津大学 | A kind of signal generator for producing multichannel microwave signal simultaneously based on optical-electronic oscillator |
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2019
- 2019-08-30 CN CN201910819037.XA patent/CN110470251B/en not_active Expired - Fee Related
Patent Citations (5)
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| JPS62159005A (en) * | 1986-01-07 | 1987-07-15 | Hitachi Cable Ltd | Measuring method for length of optical fiber |
| US5926492A (en) * | 1996-09-02 | 1999-07-20 | Nippon Telegraph & Telephone Corporation | Laser pulse oscillator |
| CN102353963A (en) * | 2011-07-15 | 2012-02-15 | 于晋龙 | Distance measuring system for optical domain based dual-loop optoelectronic oscillators |
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| Title |
|---|
| JUN HONG,SHENG等: "Fiber‐length‐dependence phase noise of injection‐locked optoelectronic oscillator", 《MICROWAVE AND OPTICAL TECHNOLOGY LETTERS》 * |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113067644A (en) * | 2021-03-05 | 2021-07-02 | 北京邮电大学 | Bias voltage control device and system of modulator |
| CN116045817A (en) * | 2023-01-09 | 2023-05-02 | 天津大学 | Micro-displacement measuring device and method based on photoelectric oscillator |
| CN116045817B (en) * | 2023-01-09 | 2023-08-01 | 天津大学 | Micro-displacement measuring device and method based on photoelectric oscillator |
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