CN110060556A - Light velocity measurement experiment instructional device and measurement method in a kind of optical fiber - Google Patents
Light velocity measurement experiment instructional device and measurement method in a kind of optical fiber Download PDFInfo
- Publication number
- CN110060556A CN110060556A CN201910368423.1A CN201910368423A CN110060556A CN 110060556 A CN110060556 A CN 110060556A CN 201910368423 A CN201910368423 A CN 201910368423A CN 110060556 A CN110060556 A CN 110060556A
- Authority
- CN
- China
- Prior art keywords
- signal
- fiber
- optical fiber
- optical
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 101
- 238000005259 measurement Methods 0.000 title claims abstract description 58
- 238000002474 experimental method Methods 0.000 title claims abstract description 31
- 238000000691 measurement method Methods 0.000 title claims description 13
- 239000000835 fiber Substances 0.000 claims abstract description 100
- 230000003287 optical effect Effects 0.000 claims abstract description 78
- 238000006243 chemical reaction Methods 0.000 claims abstract description 52
- 230000008929 regeneration Effects 0.000 claims abstract description 33
- 238000011069 regeneration method Methods 0.000 claims abstract description 33
- 230000005622 photoelectricity Effects 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 11
- 230000005540 biological transmission Effects 0.000 claims abstract description 10
- 239000004065 semiconductor Substances 0.000 claims description 9
- 238000012360 testing method Methods 0.000 claims description 6
- 230000008859 change Effects 0.000 claims description 5
- 230000004044 response Effects 0.000 claims description 4
- 239000013078 crystal Substances 0.000 claims description 3
- 230000006870 function Effects 0.000 claims description 3
- 238000004088 simulation Methods 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims 1
- 239000000126 substance Substances 0.000 claims 1
- 230000008054 signal transmission Effects 0.000 abstract description 4
- 230000006641 stabilisation Effects 0.000 abstract description 3
- 238000011105 stabilization Methods 0.000 abstract description 3
- 238000012549 training Methods 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 8
- 230000033228 biological regulation Effects 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000001172 regenerating effect Effects 0.000 description 3
- 230000003321 amplification Effects 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000013100 final test Methods 0.000 description 2
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 241001274660 Modulus Species 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000003032 molecular docking Methods 0.000 description 1
- 230000035772 mutation Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 230000009711 regulatory function Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000012358 sourcing Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J7/00—Measuring velocity of light
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
- G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
- G09B23/06—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics
- G09B23/22—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for optics
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Mathematical Physics (AREA)
- Algebra (AREA)
- Computational Mathematics (AREA)
- Mathematical Analysis (AREA)
- Mathematical Optimization (AREA)
- Optics & Photonics (AREA)
- Pure & Applied Mathematics (AREA)
- Business, Economics & Management (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Educational Administration (AREA)
- Educational Technology (AREA)
- Theoretical Computer Science (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
The invention belongs to experimental teaching equipment technical field, light velocity measurement experiment instructional device in a kind of optical fiber is disclosed.It include: that modulating signal source, modulated signal electro-optic conversion and optical signal sending module, fiber channel, the conversion of modulated signal photoelectricity and pulsewidth regeneration adjust circuit, the digital optical fiber length measuring module of XOR logic and light power meter.It is respectively that delay of the fiber channel of L1 and L2 with oscillograph to receiving end regenerated signal relative to transmitting terminal reference signal is measured twice using length under circuit delay invariant state, obtains transmission time of the modulated signal in L1-L2 fiber lengths.Fiber lengths are measured with the digital optical fiber length measuring instrument of XOR logic.According to optical signal transmission time and fiber lengths in a fiber, the light velocity in optical fiber can be calculated.Clear physics conception of the present invention, physical phenomenon is intuitive, measuring technique is novel, data stabilization, result are accurate, is the Teaching Effectively platform of training student creativity consciousness and innovation ability.
Description
Technical field
The invention belongs to light velocity measurement experiments in experimental teaching equipment technical field more particularly to a kind of optical fiber to impart knowledge to students
Device and measurement method.
Background technique
Light velocity measurement experiment is a classical Physical Experiment, but only for light, spread speed is measured in air before this
Instruments used for education, the generally acknowledged value of measurement result is c (300,000 kilometers/per second).Light is not c in the spread speed of transparent medium, and
It is c/n, n is the refractive index of transparent medium.There is no so far in instruments used for education industry clear physics conception, measurement method it is feasible,
Measuring technique is reliable, measurement data is stable and measurement result accurately measures the instrument of light spread speed in transparent medium.Light
Fibre is a kind of transparent medium, and succeeding in developing for light velocity measurement experiment instrument has just filled up this blank in optical fiber.Sichuan University's physics
Institute Zhu Shiguo professor (incumbent Chengdu Du Chuan Science & Teaching Instrument Co., Ltd legal person) delivers on " Physical Experiment " 02 phase in 2001
" light velocity measurement experiment in optical fiber " text, has started the new page of light velocity measurement experimental technique in optical fiber.But by this piece
Light velocity measurement method and the instrument and equipment of related technology production have the disadvantage that due to regenerative circuit in the optical fiber that paper provides
The saturation depth of middle transistor is not deep enough, so that the waveform of regenerated signal is unstable, leads to that measurement data is unstable, measurement
Resultant error is big；There is no the content of courses of optical fiber length measuring, fiber lengths are known given values.Related physical quantity propagates speed
It spends in the experiment of measurement, time and distance are two fundamental physical quantities to be surveyed, do not have light in light velocity measurement experiment in a fiber
The experiment of fine linear measure longimetry can't but be a very big defect；In test macro originally, reference signal is derived from modulated signal
Itself, modulated signal connects inverter input, inverter output adjusts potentiometer by optical signal magnitude and is followed by crystal three
The base stage of pole pipe.Due to the interelectrode capacity of transistor and the presence of circuit stray capacitor, just change when adjusting optical signal magnitude
The time constant of transistor base loop is become, has also just changed the circuit delay of modulated signal electro-optical conversion circuit, make
It obtains when being measured twice with double Fiber Optic Sensors, the circuit delay measured twice is inconsistent, influences optical signal and passes in a fiber
The accuracy of defeated time measurement result.
In conclusion problem of the existing technology is:
(1) saturation depth of transistor is not deep enough in regenerative circuit, so that the waveform of regenerated signal is unstable, causes
Measurement data is unstable, measuring result error is big.
(2) lack the device measured to the length of optical fiber in light velocity measurement experiment in a fiber.
(3) when carrying out Time delay measurement twice with double optical fiber, the circuit delay measured twice is inconsistent, influences optical signal and exists
The measurement result of transmission time in optical fiber.
Summary of the invention
In view of the problems of the existing technology, the present invention provides light velocity measurement experiment instructional devices in a kind of optical fiber
And measurement method.
The present invention is implemented as follows: it is that light velocity measurement experiment device for teaching, the light guide are fine in a kind of optical fiber
The structure of light velocity measurement experiment device for teaching includes: in dimension
The square-wave signal that modulating signal source --- duty ratio is 50%, the switching selection of 16 μ S/32 μ S of period；
The connection of modulating signal source and modulated signal electro-optic conversion and optical signal transmitting line --- modulating signal source exports
It is connected to the base stage of transistor BG1；Transistor BG1 emitter is connect with the input pin of inverter ic 1, defeated from inverter ic 1
The signal that foot is drawn out, as reference signal；LD connects in the collector circuit of transistor BG1；LD light power is adjusted
Device is the potentiometer W1 in transistor BG1 emitter circuit；
The connection of fiber channel and light source device LD and photoelectricity testing part PIN --- pass through fiber active linker and light
Fine tie jumper is connect with LD and PIN；
Modulated signal photoelectricity, which is converted and regenerated, adjusts circuit --- and use response wave length scope into the PIN of 900-1700nm
Photodiode makees photoelectricity testing part, is connected to regeneration and adjusts in circuit between the base stage and ground of triode BG2；Potentiometer W2 with
After resistance Rb1 series connection, the below-center offset resistance as transistor BG2；Adjusting potentiometer W2 can be changed the saturation depth of BG2；
Optical fiber length measuring instrument --- using XOR circuit as fiber lengths sensor；Utilize 7107 double-bevel moulds
The digitized measurement of the simulation trial function real world fiber length of number conversion circuit；
Light power meter --- for monitoring optical signal magnitude.
Further, the modulated signal electro-optic conversion and optical signal transmitting line use wavelength 1550nm partly leading with tail optical fiber
Body laser LD makees light source device.
Further, the fiber channel multimode fibre channel different using two length；Short fiber 2m, long optical fibers
200m—1000m。
Further, the modulated signal photoelectricity conversion and regeneration adjust the collector and open-loop voltage amplifier K of circuit BG2
Non-inverting input terminal connection, the output end of voltage amplifier K connect with the input of inverter ic 2, the output end work of inverter ic 2
For regenerated signal output end.
Further, the optical fiber length measuring instrument is equipped with zero point and adjusts and calibrate adjusting potentiometer.XOR circuit two
A input terminal connects reference signal output end and modulated signal light in modulated signal electro-optic conversion and optical signal transmitting line respectively
Electricity conversion and regeneration adjust the regenerated signal output end in circuit；XOR circuit output end is followed by double-bevel 7107 through partial pressure
31 ends foot Vin+ of analog-digital converter；The 30 foot Vin- termination zero point of 7107 double-bevel analog-digital converters adjusts the work of potentiometer W1
Moved end, 7,107 36 foot Rref+ termination calibration adjust the movable end of potentiometer W2.
Further, the light power meter calibrates wavelength 1550nm, range 0-2000 μ W；It and modulated signal photoelectricity convert and
Regeneration adjusts circuit and shares same PIN photodiode；PIN photodiode can be respectively connected to light by switching switch K
Power meter or the conversion of modulated signal photoelectricity are adjusted in circuit with regeneration.
Light velocity measurement experiment device for teaching in the optical fiber is run another object of the present invention is to provide a kind of
Light velocity measurement method in optical fiber, light velocity measurement method includes: that the signal of modulating signal source output is in the optical fiber
The square wave electrical signal that duty ratio is 50%, passes through the semiconductor laser in modulated signal electro-optic conversion and optical signal sending module
LD is converted into the square wave optical signal of duty ratio 50%；Optical signal is coupled to from LD light-emitting window with optical patchcord and optical fiber connector
In fiber channel, the other end is transferred to from fiber channel one end.It converts and regenerates by modulated signal photoelectricity in the other end and adjust
Circuit becomes the square wave electrical signal that duty ratio is 50%, referred to as regenerated signal again；Reference of the regenerated signal relative to transmitting terminal
Signal has certain delay；In delay, there is circuit delay, also there is optical path delay；Using double Fiber Optic Sensors, circuit delay not
In the state of change, long and short two optical fiber is measured twice respectively, resulting delay inequality is exactly modulated optical signal in two light
Time experienced in the distance of fine channel length difference.It further include with XOR logic number in light velocity measurement method in optical fiber
Formula optical fiber length measuring instrument measures fiber lengths.According to the measurement result of the transmission time of optical signal and fiber lengths, so that it may
Calculate the spread speed in optical fiber.
In conclusion advantages of the present invention and good effect are as follows: the present invention consists of the following components: modulating signal source,
The electro-optic conversion of modulated signal is adjusted with optical signal sending module, fiber channel, the photoelectric conversion of modulated signal and pulsewidth regeneration
The digital optical fiber length measuring module of circuit, XOR logic and light power meter.Modulating signal source output signal is that duty ratio is
50% square wave electrical signal, the square wave light for being converted into duty ratio 50% through the semiconductor laser LD in electro-optical conversion circuit are believed
Number.Optical signal is coupled in fiber channel from LD light-emitting window with optical patchcord and optical fiber connector, is transmitted from fiber channel one end
To the other end.Circuit, which is adjusted, by photoelectric conversion and regeneration in the other end of fiber channel becomes the side that duty ratio is 50% again
Wave electric signal, referred to as regenerated signal (same as below).The regenerated signal square wave electrical signal original relative to transmitting terminal has certain
Delay (measurement of available digital oscillograph).In this delay, there is circuit delay, also there is optical path delay.Using double Fiber Optic Sensors,
In the state that circuit delay is constant, two optical fiber that length differs greatly are measured twice respectively, resulting delay inequality is just
It is modulated optical signal time experienced in the distance of two fiber channel length differences.With the digital fiber lengths of XOR logic
The length of measuring instrument measurement optical fiber.According to the transmission time and optical fiber length measuring data of optical signal in a fiber, can calculate
The light velocity in optical fiber.
Compared with prior art, present invention has the advantage that
(1) stability of reproduction waveform greatly improves: being the square-wave modulation signal that 16 μ S are for the period, can make regeneration electricity
The positive pulse width jitter of signal is within the scope of positive and negative 10nS；
(2) the adjusting fineness of regenerated signal pulsewidth greatly improves: it is the square-wave modulation signal that 16 μ S are for the period, it can
Make to regenerate within the scope of the degree of regulation 1-10nS of the positive pulsewidth of electric signal；
(3) due to using laser and the wavelength response range of 1550nm wavelength as the PIN photoelectricity two of 900-1700nm
The length of pole pipe, the long optical fibers channel of measuring system can increase to 1000m or more from original 200m, greatly reduce circuit delay
Measurement is inaccurate, and on optical signal, transmission time measurement result bring influences in a fiber.
(4) final measurement: measurement data is reliable and stable, accurate.
The clear physics conception of light velocity measurement experiment, physical phenomenon be intuitive in optical fiber according to the present invention, measurement method
Ingenious and measuring technique is novel, measurement data is stable, result is accurate, can build for the creativity consciousness and innovation ability of training student
One highly effective teaching platform.
Detailed description of the invention
Fig. 1 is light velocity measurement experiment instructional device structural schematic diagram in optical fiber provided in an embodiment of the present invention.
Fig. 2 is the electro-optic conversion and optical signal transmitting line schematic diagram of modulated signal provided in an embodiment of the present invention.
Fig. 3 is that optical signal photoelectric conversion provided in an embodiment of the present invention and regeneration adjust circuit diagram.
Fig. 4 is XOR logic fiber lengths Fundamentals of Sensors schematic diagram provided in an embodiment of the present invention.
Fig. 5 is XOR logic fiber lengths sensor senses characteristic schematic diagram provided in an embodiment of the present invention.
Fig. 6 is the digital optical fiber length measuring instrument structural schematic diagram of XOR logic provided in an embodiment of the present invention.
Fig. 7 is that the digital optical fiber length measuring instrument zero point of XOR logic provided in an embodiment of the present invention adjusts measuring system company
Connect schematic diagram.
Fig. 8 is that the digital optical fiber length measuring calibration of XOR logic provided in an embodiment of the present invention adjusts measuring system connection
Schematic diagram.
In Fig. 1: 1, modulating signal source；2, light source device modulation and driving circuit；3, transmission fiber；4, the photoelectricity of signal turns
It changes and regenerative circuit；5, fiber lengths analyzer；6, light power meter；7, digital oscilloscope.
Specific embodiment
For that can further appreciate that the contents of the present invention, feature and effect, the following examples are hereby given, and cooperates attached drawing detailed
It is described as follows:
In view of the problems of the existing technology, light velocity measurement experiment instructional device in a kind of optical fiber provided by the invention
It consists of the following components: modulating signal source, the electro-optic conversion of modulated signal and optical signal sending module, fiber channel, modulation
Photoelectric conversion and the pulsewidth regeneration of signal adjust circuit, the digital optical fiber length measuring module of XOR logic and light power meter.
Application principle of the invention is explained in detail with reference to the accompanying drawing.
As shown in Figure 1, light velocity measurement experiment instructional device includes: modulation letter in optical fiber provided in an embodiment of the present invention
Number source 1, the electro-optic conversion of modulated signal and optical signal sending module 2, fiber channel 3, modulated signal photoelectric conversion and regeneration
Adjust circuit 4, the digital optical fiber length measuring module 5 of XOR logic, light power meter 6 and digital oscilloscope 7.
The signal that modulating signal source 1 exports is the square wave electrical signal that duty ratio is 50%, passes through modulated signal electro-optic conversion
And the semiconductor laser LD in optical signal sending module 2, it is converted into the square wave optical signal of duty ratio 50%.Optical signal goes out from LD
Optical port optical patchcord and optical fiber connector are coupled in fiber channel 3, are transferred to the other end from 3 one end of fiber channel.Another
One end is converted and is regenerated by modulated signal photoelectricity adjusting circuit 4 and becomes the square wave electrical signal that duty ratio is 50% again, referred to as
Regenerated signal (same as below).Reference signal of the regenerated signal relative to transmitting terminal has certain delay (available digital oscillography
Device 7 measures).In this delay, there is circuit delay, also there is optical path delay.Using double Fiber Optic Sensors, in the state that circuit delay is constant
Under, long and short two optical fiber is measured twice respectively, resulting delay inequality is exactly that modulated optical signal is long in two fiber channels
Spend the time experienced in the distance of difference.
The light velocity must measure the length of optical fiber in measurement optical fiber.It is long that time domain reflectometry measurement optical fiber is commonly used in optical fiber engineering
Degree, be by the light velocity in optical fiber be 200,000 kilometer per seconds datum based on, according to light pulse in a fiber the turnaround time calculate light
Fine length.What the present invention to be measured is exactly that (light velocity is a unknown number in optical fiber for the light velocity in optical fiber！), so time domain cannot be applied
Reflectometer is as optical fiber length measuring instrument.The digital optical fiber length measuring instrument of the XOR logic that the present invention is arranged, is that one kind has
The novel optical fiber linear measure longimetry instrument of innovative characteristics, it is instrument indispensable in light velocity measurement experiment in optical fiber.It is using different
Or logic circuit realizes fiber lengths as fiber lengths sensor, using the simulation trial function of double-bevel analog to digital conversion circuit
Digitized measurement (in relation to principle and the narration that sees below of operation).
According to the length of modulated optical signal transmission time in a fiber and fiber channel, the light in optical fiber can be calculated
Speed.
The present invention joins to enhance the stability, the reliability of measurement data and accuracy of regenerated signal waveform in circuit
Great change has been made on number, and the upper biasing resistor Rb2 of transistor BG2 in Fig. 3 is changed to 1-10K range from original 100K
It is adjustable.In this adjustable range, in photodiode no light, transistor BG2 can be in deep saturation shape
State.
The difference of circuit delay, has reelected reference signal when the present invention is measured to eliminate with double Fiber Optic Sensors twice
Output point and optical signal magnitude adjust the position of potentiometer.Referring to Fig. 2, reference signal is brilliant from modulated signal electro-optical conversion circuit
Subsequent 1 output end of inverter ic of body triode BG1 emitter is drawn；Optical signal magnitude adjusts potentiometer W1 and connects in three pole of crystal
In pipe BG1 emitter circuit.
The present invention, can when photodiode has illumination in order to make the transistor BG2 in Fig. 3 under deep saturation state
It is detached from saturation state, into amplification region phase inverter thereafter is quickly overturn, light source device used in measuring system
Large-power semiconductor laser LD is changed to from the SPD of original small luminous power LED and low-response degree with photoelectricity testing part
With the PIN photodiode of high-responsivity.
Modulating signal source is the square wave signal generator that duty ratio is 50%.16 μ S/32 μ S of its period is changeable, specific to select
It selects, depending on the length of fiber channel.Total principle is the half period (T/2) of modulated signal, should be greater than or be equal to measuring system
The sum total of circuit delay and optical path delay.
Application principle of the invention is further described with reference to the accompanying drawing.
The square wave electrical signal that modulating signal source 1 exports, modulated signal electro-optic conversion and optical signal sending module 2 are converted into
The square wave optical signal that duty ratio is 50%.With optical fiber tie jumper and fiber active linker, optical signal from modulated signal
The light-emitting window of semiconductor laser diode LD is coupled in fiber channel 3 in electro-optic conversion and optical signal sending module 2, and passes
The defeated other end to fiber channel 3.In the other end of fiber channel 3, the light wave containing optical signal is shone with optical fiber tie jumper
Penetrate on the PIN photodiode photosurface adjusted in the photoelectric conversion of modulated signal and regeneration in circuit 4, by photoelectric conversion and
Regeneration adjusts the square wave electrical signal (referred to as regenerated signal --- same as below) for becoming that duty ratio is 50% again.Regenerated signal phase
For the reference signal of transmitting terminal, there is certain delay.In this delay, existing circuit delay also has optical path delay.Using
Double Fiber Optic Sensors, in the state that circuit delay is constant, to length be L1 long optical fibers channel and phase length be L2 short fiber believe
Road, measured twice respectively resulting delay inequality be exactly modulated optical signal in L1-L2 apart from the interior time experienced.
In order to measure delay of the regenerated signal with respect to reference signal, the electro-optic conversion and optical signal of modulated signal are sent mould
The photoelectric conversion of reference signal and modulated signal in block 2 and the regenerated signal in regeneration adjusting circuit 4 are coupled with number and show
The channel CH1 and CH2 of wave device 7.
In order to measure the length of fiber channel, need in electro-optic conversion and optical signal sending module 2 modulated signal
It is digital that the photoelectric conversion and the regenerated signal in regeneration adjusting circuit 4 of reference signal and modulated signal are coupled with XOR logic
Corresponding reference signal and measured signal end in optical fiber length measuring module 5.
The zero point of the digital optical fiber length measuring instrument of XOR logic is adjusted to be adjusted with calibration --- and first accessing length is L2's
Short fiber channel carries out zero point adjusting；Then the fiber channel for accessing known length, carries out calibration adjusting.
According to the light velocity that can be calculated after the transmission time and fiber channel length of the optical signal measured in a fiber in optical fiber.
In order to obtain stable and accurate measurement result, it is desirable that the waveform of regenerated signal is sufficiently stable, regeneration adjusts circuit
Degree of regulation it is thin.After the present invention takes the above measure, the square-wave modulation signal for being 16 μ S for the period can make to regenerate telecommunications
Number positive pulse width jitter is within the scope of positive and negative 10nS.Regeneration adjusts the degree of regulation of circuit, can make the minimum of the positive pulsewidth of regenerated signal
Increase and decrease amount is in the 1-10nS order of magnitude.Final testing result: data stabilization, accurate.
The electro-optic conversion and optical signal sending module of modulated signal
The electro-optical conversion circuit of modulated signal is as shown in Fig. 2.In the circuit, using wavelength 1550nm, with tail optical fiber
Semiconductor laser LD makees light source device.LD connects in transistor triode BG1 collector circuit.Modulating signal source output is connected to
The base stage of transistor triode BG1.It is defeated by optical fiber tie jumper from the light-emitting window of LD after modulation signal is converted into optical signal
Out.The series and parallel compensated resistance of resistance Rb1, Rb2 and potentiometer W1 composition connects between transistor BG1 emitter and ground, adjusts
W1 can change optical signal magnitude.Reference signal is drawn from 1 output pin of inverter ic.
Fiber channel
Fiber channel is furnished with double fiber channels.In attached drawing 2 from the optical fiber tie jumper of LD light-emitting window output optical signal with
The optical fiber tie jumper for the illumination containing optical signal being guided in attached drawing 3 PIN photodiode photosurface, is flexibly connected with optical fiber
Device just forms short fiber channel after being docking together；Above two optical fiber tie jumpers are separated from fiber active linker, are led to
The fiber channel both ends for crossing other two fiber active linker and length 1000m are rear with regard to composition long optical fibers channel to connecting.
The photoelectric conversion of optical signal and regeneration adjust circuit
No matter the measurement of fiber lengths or modulated signal transmission time in a fiber, be all in receiving end regenerated signal duty
Than what is carried out in the case where as transmitting terminal reference signal duty ratio.So measuring system must have modulated signal photoelectricity to turn
It changes and pulsewidth regenerates regulatory function.Photoelectric conversion and pulsewidth regeneration adjust the task of circuit, are exactly the light that transmission fiber is exported
Signal (duty ratio 50%) adjusts circuit transformations by PIN photodiode and pulsewidth regeneration in receiving end and appoints so at duty ratio
It is 50% square wave electrical signal.The structure such as attached drawing 3 that photoelectric conversion and pulsewidth regeneration adjust circuit shows.Working principle is as follows: logical
Crossing optical fiber tie jumper and being incident on the optical signal of PIN photodiode photosurface is square wave optical signal that light intensity cuts in and out, is accounted for
Sky is than being also 50%.When optical signal is in unglazed period, PIN photodiode is flowed through without photoelectric current, if at this moment R c, Rb1,
The resistance value of Rb2 and W2 is appropriate, and transistor BG2 just has sufficiently large base current I b injection, and transistor BG2 is made to be in deep
Spend saturation state.Therefore the voltage between its collector and emitter is extremely low, has both made to put by subsequent amplifying circuit high power
Also the output voltage of inverter ic 2 can be made to maintain high level state after big.When optical signal, which is in, light state, PIN photoelectricity
Diode has photoelectric current IOIt generates, it is to flow to anode from the cathode of PIN photodiode, to the base stage of transistor BG2
Electric current IbWith sourcing current effect, reduce the base current of BG2.Due to PIN photodiode junction capacity, the line of foot wiring out
Between between capacitor and BG2 base-emitter-base bandgap grading stray capacitance presence so that this reduction process of BG2 base current be not mutation
, but by the variation of the exponential law of sometime constant.With the reduction of BG2 base current, BG2 progressively disengages depth saturation
Area, to shallow saturation region and amplification region transition, the voltage Vc e between Collector Emitter also start exponentially gradually on
It rises.Since subsequent amplifier magnification ratio is very high, therefore do not wait until that Vc e rises to its asymptotic value also, amplifier output voltage is just
Reach the voltage value for overturning 2 state of inverter ic, at this moment IC2 output end is low level.In next unglazed shape of optical signal
When state arrives, again without photoelectric current, the base current I b of BG2 is exponentially gradually increased PIN photodiode again, thus
Originally the Vce for exponentially increase BG2 just stops rising when reaching a certain value, and starts exponentially to decline.Vce
After dropping to a certain value, IC2 is turned into high level by low level.The optical signal certain for amplitude, it is appropriate to adjust BG2 below-center offset
The resistance value of W2 in circuit, changes the saturation depth of BG2, and the square-wave signal that photoelectric conversion and regeneration can be made to adjust circuit output accounts for
Sky is than being 50%.
The digital optical fiber length measuring instrument of XOR logic
The digital optical fiber length measuring instrument of XOR logic is by XOR logic fiber lengths sensor and 7107 double-bevel moduluses
Converter two parts composition.
XOR logic fiber lengths sensor such as attached drawing 4 shows, the reference signal output end and reception that the transmitting terminal period is T
The regenerated signal output at end is when terminating to two input terminals of XOR circuit, and output waveform is exactly that a cycle is T/2, but
The pulsewidth square wave sequence directly proportional to its relative time delay τ of two input signals.When two-way input signal delay τ is in 0-T/2
In the range of when, the direct current level values V of this square wave sequenceoIn VLWith VhJust there is following proportional relation with τ in range:
Vo=VL+[2(Vh-VL)τ/T]
V in above formulaLThe low level value that XOR gate exports when being two-way input signal same-phase, VhIt is two-way input signal
The high value that XOR gate exports when antiphase.So XOR circuit is in the application that attached drawing 4 shows, it is exactly a kind of delay
Sensor.Due in the relative time delay of XOR circuit two-way input signal, including circuit delay and optical path are delayed two parts,
Wherein optical path delay is directly proportional to the length of fiber channel.Measuring system will not be made always to be delayed in fiber lengths is more than the model of T/2
In enclosing, above formula can also be changed to:
Vo=a+K*L
So the above-mentioned usage of XOR circuit and a fiber lengths sensor, sensing characteristics such as figure attached drawing 5
Show.Wherein intercept a (dimension: volt), it is related with the cycle T of the circuit delay of measuring system, modulated signal；Slope K (dimension: volt/
Rice) with the low and high level V of the light velocity to be measured, the cycle T of modulated signal and XOR circuith、VLIt is related.
Fiber lengths digital measuring technique
XOR circuit is fiber lengths sensor, and the digitized measurement of Yao Shixian fiber lengths must also be using double
7107 modulus conversion chip of inclined and matched charactron.It theoretically proves: as long as modulated signal in measuring system of the present invention
Cycle T is much smaller than the charging time of integrating capacitor in double-bevel analog to digital conversion circuit measurement process (for the measurement in the present invention
System is to meet this requirement condition), double-bevel analog to digital conversion circuit just can be used to measure the square wave of XOR circuit output
The DC level of sequence.Specific connection such as the attached drawing 6 of measuring circuit shows: point of resistance R1, R2 composition is passed through in XOR logic output
Volt circuit partial pressure is followed by 7107 chip Vin+The V that foot, the benefit reward voltage regulator circuit being made of potentiometer W1 exportbIt is connected to
7107 chip Vin-The output (movable end of W2) that foot, the calibration being made of potentiometer W2 adjust circuit is connected to 7107 chip Vref+
Foot.In this way, attached drawing 6 shows that circuit is exactly a fiber lengths comparison circuit.On the basis of this comparison circuit, through zero crossing tune
It saves and just constitutes a digital optical fiber length measuring after using the optical fiber of known length to carry out calibration calibration as standard fiber
Instrument.When selecting 32 μ S in the period of modulated signal, the range of optical fiber length measuring instrument is 0-2000m in the present invention.
The zero point of optical fiber length measuring instrument is adjusted and range adjusting concrete operations are as follows:
Zero point, which is adjusted, shows connection measuring system by attached drawing 7, after the regeneration adjusting for completing modulated signal, adjusts in attached drawing 6
Potentiometer W1 makes the digital display 0000 of 7107 analog-to-digital conversions.
Range, which is adjusted, shows connection measuring system by attached drawing 8, keeps the potentiometer in the potentiometer W1 and attached drawing 3 in attached drawing 6
W2 adjustment state is constant, after adjusting the regeneration adjusting that the optical signal magnitude in attached drawing 2 adjusts potentiometer W1 completion modulated signal, adjusts
The potentiometer W2 in attached drawing 6 is saved, the digital display 0200 of 7107 analog-to-digital conversions is made.
The measurement of optical signal transmission time
It is measured twice using double fiber channels, shows connection measuring system by attached drawing 1, access length when measuring for the first time
For the long optical fibers channel of L1.Reference signal is exported the termination channel digital oscilloscope CH1, regenerated signal output terminates digital oscillography
The channel device CH2.W1 potentiometer in attached drawing 2 is adjusted, after electric current 20mA for flowing through semiconductor laser LD or so, adjusting attached drawing
The positive pulsewidth for the square-wave signal waveform that the channel digital oscilloscope CH2 occurs in potentiometer W2 in 3 and the channel digital oscilloscope CH1
The positive pulsewidth of the waveform of display is identical.The channel CH2 square-wave signal prolonging relative to the channel CH1 square-wave signal is observed with digital oscilloscope
When τ 1.It when second of measurement, keeps the other connections of measuring system constant, replaces long optical fibers to believe by the short fiber channel of L2 with length
Road accesses measuring system.After this, it keeps the adjustment state of potentiometer W2 in attached drawing 3 constant, adjusts the potentiometer in attached drawing 2
The square wave that W1, the positive pulsewidth for the square-wave signal for again occurring the channel digital oscilloscope CH2 and the channel digital oscilloscope CH1 are shown
The positive pulsewidth of signal is identical.The channel CH2 square-wave signal prolonging relative to the channel CH1 square-wave signal is observed with digital oscilloscope again
When τ2。(τ1-τ2) it is exactly optical signal in (L1-L2) transmission time in fiber lengths.
In order to obtain stable and accurate measurement result, it is desirable that the waveform of regenerated signal is sufficiently stable, regeneration adjusts circuit
Degree of regulation it is thin.After the present invention takes the above special measure, it is the square-wave modulation signal that 16 μ S are for the period, can makes again
The raw positive pulse width jitter of electric signal is within the scope of positive and negative 10nS.Regeneration adjusts the degree of regulation of circuit, can make the positive pulsewidth of regenerated signal
Minimum increase and decrease amount in the 1-10nS order of magnitude.Final testing result: data stabilization, result are accurate.Specific measurement data is as follows:
L1=1251m, τ1=8.0 μ S.
L2=215m, τ2=2.8 μ S.
Calculated result: the light velocity in optical fiber: 19.923*104Km/S。
The present invention enters the teaching implementation stage in colleges and universities such as Jiujiang University, flight institute, civil aviaton, Guangdong University of Technology.
It is proved according to the feedback information of these schools: by light velocity measurement experiment in the optical fiber of Chengdu Du Chuan Science & Teaching Instrument Co., Ltd research and development
The instrument content of courses is novel, principle is correct, clear physics conception, measurement data are stable, final calculation result is accurate.
The above is only to measuring system structure, measuring principle, measuring technique and measurement method of the invention, use
Crucial photoelectric device, the extraction of reference signal, the regulative mode of optical signal magnitude, modulated signal regeneration techniques and fiber lengths
The problems such as measuring technique, has been made more to be discussed in detail.These discussions are not intended to limit the present invention in any form, it is all according to
According to any simple modification or equivalent variations and modification that the above technical spirit of the invention makes problem above, belong to this
Within the scope of the infringement of inventive technique scheme.
Claims (7)
1. the light velocity measures experiment device for teaching in a kind of optical fiber, which is characterized in that light velocity measurement religion in the optical fiber
Learning experimental provision includes:
Modulating signal source is the square-wave signal that duty ratio is 50%, the switching selection of 16 μ S/32 μ S of period；
Modulated signal electro-optic conversion and optical signal transmitting line, connect with modulating signal source, and modulating signal source output is connected to crystal
The base stage of pipe BG1；Transistor BG1 emitter is connect with the input pin of inverter ic 1, is drawn from 1 output pin of inverter ic
Signal, as reference signal；LD connects in the collector circuit of transistor BG1；LD light power regulating device is brilliant
Potentiometer W1 in body triode BG1 emitter circuit；
Fiber channel is connected by fiber active linker and optical fiber tie jumper and light source device LD and photoelectricity testing part PIN
It connects；
The conversion of modulated signal photoelectricity and regeneration adjust circuit, use response wave length scope for two pole of PIN photoelectricity of 900-1700nm
Pipe makees photoelectricity testing part, is connected to regeneration and adjusts in circuit between the base stage and ground of triode BG2；Potentiometer W2 and resistance Rb1
Below-center offset resistance after series connection, as transistor BG2；Adjusting potentiometer W2 can be changed the saturation depth of BG2；
Optical fiber length measuring instrument using XOR circuit as fiber lengths sensor, utilizes 7107 double-bevel analog-to-digital conversions
The digitized measurement of the simulation trial function real world fiber length of circuit；
Light power meter, for monitoring optical signal magnitude.
2. the light velocity measures experiment device for teaching in optical fiber as described in claim 1, which is characterized in that the modulated signal
Electro-optic conversion and optical signal transmitting line use wavelength 1550nm to make light source device with the semiconductor laser LD of tail optical fiber, connect in crystalline substance
In body pipe BG1 collector circuit.
3. the light velocity measures experiment device for teaching in optical fiber as described in claim 1, which is characterized in that the fiber channel
Using the different multimode fibre channel of two length；Short fiber 2m, long optical fibers 200m -1000m.
4. the light velocity measures experiment device for teaching in optical fiber as described in claim 1, which is characterized in that the modulated signal
The collector that photoelectric conversion and regeneration adjust circuit BG2 is connect with the non-inverting input terminal of open-loop voltage amplifier K, voltage amplifier
The output end of K is connect with the input of inverter ic 2, and the output end of inverter ic 2 is as regenerated signal output end.
5. the light velocity measures experiment device for teaching in optical fiber as described in claim 1, which is characterized in that the fiber lengths
Measuring instrument is equipped with zero point and adjusts and calibrate adjusting potentiometer；Two input terminals of XOR circuit connect modulated signal electric light respectively and turn
Change and the reference signal output end in optical signal transmitting line and modulated signal photoelectricity conversion and regeneration adjust circuit in regeneration
Signal output end；XOR circuit output end is followed by 31 ends foot Vin+ of 7107 analog-digital converter of double-bevel through dividing；7107
The 30 foot Vin- termination zero point of double-bevel analog-digital converter adjusts the movable end of potentiometer W1, and 7,107 36 foot Rref+ terminate school
Standard adjusts the movable end of potentiometer W2.
6. the light velocity measures experiment device for teaching in optical fiber as described in claim 1, which is characterized in that the light power meter
Calibrate wavelength 1550nm, range 0-2000 μ W；It is converted with modulated signal photoelectricity and regenerates adjusting circuit and share same PIN photoelectricity two
Pole pipe；By switch switch K PIN photodiode can be respectively connected to light power meter or modulated signal photoelectricity conversion and again
It is raw to adjust in circuit.
7. light velocity measurement in the optical fiber of light velocity measurement experiment device for teaching in optical fiber described in a kind of operation claim 1
Method, which is characterized in that it is that duty ratio is that light velocity measurement method, which includes: the signal of modulating signal source output, in the optical fiber
50% square wave electrical signal passes through the semiconductor laser LD in modulated signal electro-optic conversion and optical signal sending module, conversion
At the square wave optical signal of duty ratio 50%；Optical signal is coupled to fiber channel with optical patchcord and optical fiber connector from LD light-emitting window
It is interior, the other end is transferred to from fiber channel one end；It converts and regenerates by modulated signal photoelectricity in the other end and adjust circuit again
Become the square wave electrical signal that duty ratio is 50%, referred to as regenerated signal；Reference signal of the regenerated signal relative to transmitting terminal, has
Certain delay；In delay, there is circuit delay, also there is optical path delay；Using double Fiber Optic Sensors, in the state that circuit delay is constant
Under, long and short two optical fiber is measured twice respectively, resulting delay inequality is exactly that modulated optical signal is long in two fiber channels
Spend the time experienced in the distance of difference；It further include long with the digital optical fiber of XOR logic in light velocity measurement method in optical fiber
Degree measuring instrument measures fiber lengths；According to the measurement result of the transmission time of optical signal and fiber lengths, so that it may calculate light
Spread speed in fibre.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910368423.1A CN110060556A (en) | 2019-05-05 | 2019-05-05 | Light velocity measurement experiment instructional device and measurement method in a kind of optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910368423.1A CN110060556A (en) | 2019-05-05 | 2019-05-05 | Light velocity measurement experiment instructional device and measurement method in a kind of optical fiber |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110060556A true CN110060556A (en) | 2019-07-26 |
Family
ID=67322140
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910368423.1A Withdrawn CN110060556A (en) | 2019-05-05 | 2019-05-05 | Light velocity measurement experiment instructional device and measurement method in a kind of optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110060556A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110556045A (en) * | 2019-09-19 | 2019-12-10 | 南安市美胤机械科技有限公司 | Light velocity measurement experiment teaching equipment in optical fiber |
| CN113328793A (en) * | 2021-06-17 | 2021-08-31 | 西北核技术研究所 | Remote optical fiber transmission delay testing method and system based on time domain reflection difference |
| WO2023087510A1 (en) * | 2021-11-19 | 2023-05-25 | 上海御渡半导体科技有限公司 | Analog measurement apparatus and measurement method based on digital tdr technology |
-
2019
- 2019-05-05 CN CN201910368423.1A patent/CN110060556A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110556045A (en) * | 2019-09-19 | 2019-12-10 | 南安市美胤机械科技有限公司 | Light velocity measurement experiment teaching equipment in optical fiber |
| CN113328793A (en) * | 2021-06-17 | 2021-08-31 | 西北核技术研究所 | Remote optical fiber transmission delay testing method and system based on time domain reflection difference |
| WO2023087510A1 (en) * | 2021-11-19 | 2023-05-25 | 上海御渡半导体科技有限公司 | Analog measurement apparatus and measurement method based on digital tdr technology |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110060556A (en) | Light velocity measurement experiment instructional device and measurement method in a kind of optical fiber | |
| CN101839698A (en) | BOTDR (Brillouin Optical Time Domain Reflectometer) for calibrating optical power of reference light and calibrating method thereof | |
| CN100554902C (en) | Be applicable to the temperature simple calibrating method of reflection-type polarization-preserving fiber temperature sensor | |
| CN101881669B (en) | Real-time closed-loop measuring and tracking method of half-wave voltage of integrated electro-optical phase modulator | |
| CN101881808A (en) | Organic electroluminescent diode service life tester | |
| CN102200671B (en) | Extinction ratio debugging device and method of optical module | |
| CN105867497A (en) | MZ modulator bias voltage self-adaption control method | |
| CN103413747A (en) | Space plasma measuring device | |
| CN203688743U (en) | OLED device optical and electrical property testing system | |
| CN106443126A (en) | Method and device for measuring half-wave voltage of electro-optical crystal | |
| CN102866000A (en) | Laser detection system | |
| CN102175941B (en) | Optical coupler measurement device capable of directly displaying current transfer ratio | |
| CN105044536A (en) | Novel packaging defect detection method and novel packaging defect detection system | |
| CN107356412B (en) | A kind of measurement method of the measuring system based on rare-earth doped optical fibre refractive index | |
| CN204758000U (en) | A pulse light signal generating device for distributed optical fiber sensing system | |
| CN206192502U (en) | Calibration arrangement for from mixing terahertz detector response parameter | |
| CN210466951U (en) | Light velocity measurement experiment teaching device in optical fiber | |
| CN106154130B (en) | A kind of photo-electric surge voltage test device and method | |
| CN113097860B (en) | Semiconductor laser driving current circuit and output frequency real-time feedback method | |
| CN110132136A (en) | A kind of digital optical fiber length measuring system of XOR logic | |
| CN106253976B (en) | A kind of optical signal generation apparatus and production method | |
| CN1804949B (en) | Integrated photoelectrical experiment and test method | |
| CN102706476A (en) | High-accuracy fast temperature measuring method based on Sagnac fibre optic interferometer | |
| CN215984388U (en) | XOR logic digital optical fiber length measuring system | |
| CN2720457Y (en) | Semiconductor laser characteristic parameter testing device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WW01 | Invention patent application withdrawn after publication |
Application publication date: 20190726 |
|
| WW01 | Invention patent application withdrawn after publication |