CN113507317A - Optical fiber fault monitoring device and method based on incoherent optical frequency domain reflection - Google Patents
Optical fiber fault monitoring device and method based on incoherent optical frequency domain reflection Download PDFInfo
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Abstract
The utility model provides an optical fiber fault monitoring device and method based on incoherent optical frequency domain reflection, which comprises a digital signal processor; the digital signal processor drives the direct digital frequency synthesizer to output two paths of signals through the control bus, one path of signal is input into the laser driver, and the laser driver drives the semiconductor laser to generate continuous light waves with step frequency modulation; the other path of signal is input into a receiver; the continuous light wave is input into a first port of the circulator and is emitted into the sensing optical fiber through a second port; rayleigh scattered light waves generated on the sensing optical fiber are emitted into the photoelectric detector through the third port, and the photoelectric detector converts the rayleigh scattered light waves into weak current signals and transmits the weak current signals to the receiver; the receiver converts weak current signals related to Rayleigh scattering into digital signals, transmits the digital signals to the digital signal processor, and processes the digital signals through the digital signal processor to realize monitoring of optical fiber faults.
Description
Technical Field
The disclosure belongs to the technical field of optical fiber fault monitoring, and particularly relates to an optical fiber fault monitoring device and method based on incoherent optical frequency domain reflection.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
At present, optical fibers are the basis of optical communication transmission networks, and the performance of the fiber core of the optical fibers directly influences the performance of the transmission networks. In the case of the fault of the comprehensive transmission network, the fault caused by fiber breakage and the degradation of the quality of the optical fiber accounts for a large proportion, and the frequent occurrence of the optical fiber fault is difficult to find and process in advance.
The existing Optical fiber fault positioning means is generally based on monitoring of a traditional OTDR (Optical time domain Reflectometer) instrument on an Optical fiber, wherein the OTDR test principle is that a laser light source emits pulsed light with certain intensity and wavelength to a measured Optical fiber; due to the characteristics of the optical fiber and the nonuniformity of impurity components, the pulsed light is transmitted in the optical fiber and generates Rayleigh scattering; due to mechanical connection and breakage, fresnel reflections occur as the pulsed light is transmitted in the fiber, and some of the scattered and reflected light is transmitted back to the input end. The length of the optical fiber can be calculated by the time of transmission and return of the pulsed light in the optical fiber and the transmission speed of the pulsed light in the optical fiber.
However, the inventor found that in the OTDR measurement technique, the narrower the time width of the pulsed light, the better the positioning resolution, but the worse the signal-to-noise ratio and the dynamic range, the shorter the fiber measurement length; the wider the time width of the pulse light, the poorer the positioning resolution, but the better the signal-to-noise ratio and the dynamic range, and the longer the measurement length of the optical fiber, so that the contradiction exists between the spatial resolution of the OTDR measurement technology and the signal-to-noise ratio, the dynamic range and the measurement length; in general, the positioning resolution that the OTDR measurement technique can realize mostly belongs to the meter level, and the measurement length is about 10-30 km, which cannot be effectively applied to the remote optical fiber measurement condition.
Disclosure of Invention
In order to solve the above problems, the present disclosure provides an optical fiber fault monitoring device and method based on incoherent optical frequency domain reflection, in the scheme, based on the fact that rayleigh scattering return signals and local oscillation signals are merged at a mixer, and quality monitoring of the whole sensing optical fiber at a certain frequency point is realized through analog signal processing and analog-to-digital conversion; meanwhile, the optical frequency of the laser is changed to scan, so that frequency domain information related to the health state of the whole sensing optical fiber optical network can be obtained, and the spatial domain information of the optical network health state distributed along the sensing optical fiber can be obtained by means of inverse Fourier transform, so that online fault monitoring of the optical fiber network is realized, and the detection efficiency and precision are effectively improved.
According to a first aspect of the embodiments of the present disclosure, there is provided an optical fiber fault monitoring device based on incoherent optical frequency domain reflection, including a digital signal processor;
the digital signal processor drives the direct digital frequency synthesizer to output two paths of signals through the control bus, one path of signal is input into the laser driver, and the laser driver drives the semiconductor laser to generate continuous light waves with step frequency modulation; the other path of signal is input into a receiver; the continuous light wave is input into a first port of the circulator and is emitted into the sensing optical fiber through a second port; rayleigh scattered light waves generated on the sensing optical fiber are emitted into the photoelectric detector through the third port, and the photoelectric detector converts the rayleigh scattered light waves into weak current signals and transmits the weak current signals to the receiver;
the receiver converts weak current signals related to Rayleigh scattering into digital signals, transmits the digital signals to the digital signal processor, and processes the digital signals through the digital signal processor to realize monitoring of optical fiber faults.
Further, the digital signal processor processes the digital signal, specifically: obtaining frequency domain information related to the health state of the optical network according to the Rayleigh scattering signals of all frequency points of the stepping frequency; and carrying out inverse Fourier transform on the frequency domain information to obtain the information of the spatial distribution related to the health state of the optical network.
Further, the receiver converts the weak current signal related to rayleigh scattering into a digital signal, specifically: and aiming at Rayleigh scattering current signals returned by all frequency points of the stepping frequency, carrying out frequency mixing by using an oscillating clock with fixed frequency to obtain frequency domain information of the whole sensing optical fiber related to the health state of the optical network, and converting the frequency domain information into a digital signal.
Furthermore, the digital signal processor drives the direct digital frequency synthesizer to output two paths of signals through the control bus, wherein one path of signals is a continuous step frequency sweep signal, and the other path of signals is a single-frequency signal with fixed frequency.
Further, the continuous light wave is input into the first port of the circulator and is emitted into the sensing optical fiber through the second port, and when the continuous light wave propagates along the sensing optical fiber, rayleigh scattered light waves related to the health state of the optical network are generated and are absorbed into the photodetector through the third port.
Further, the receiver comprises a transimpedance amplifier, a mixer, a high-precision analog amplifier and an analog-to-digital converter which are connected in sequence.
Further, the transimpedance amplifier converts a weak current signal output by the photoelectric detector into a voltage signal and outputs the voltage signal to a radio frequency input end of the frequency mixer.
According to a second aspect of the embodiments of the present disclosure, there is provided an optical fiber fault monitoring method based on incoherent optical frequency domain reflection, which utilizes the above-mentioned optical fiber fault monitoring apparatus based on incoherent optical frequency domain reflection, including:
controlling a semiconductor laser to generate continuous light waves with step frequency modulation through a laser driver;
inputting the continuous light wave with the step frequency modulation into a sensing optical fiber, and generating Rayleigh scattering light waves related to the health state of an optical network;
aiming at Rayleigh scattering related electric signals returned by all frequency points of the stepping frequency, using a local oscillation clock with fixed frequency to carry out frequency mixing to obtain frequency domain information of the whole sensing optical fiber related to the health state of the optical network;
and performing Fourier inverse transformation on the frequency domain information to obtain spatial domain information of the optical network health state distributed along the sensing optical fiber, further obtaining fault information and position information along the measured optical fiber, and realizing monitoring of optical fiber faults.
Compared with the prior art, the beneficial effect of this disclosure is:
(1) the scheme is that the light emitted by a laser light source is subjected to stepping frequency modulation, and is emitted into a long-distance optical fiber after passing through an optical circulator, a Rayleigh scattering return signal and a local oscillation signal are converged at a mixer, and the quality monitoring of the whole sensing optical fiber at a certain frequency point is realized through analog signal processing and analog-to-digital conversion; the frequency domain information related to the health state of the whole sensing optical fiber optical network can be obtained by changing the light emitting frequency of the laser to scan, and the spatial domain information of the health state of the optical network distributed along the sensing optical fiber can be obtained by means of inverse Fourier transform, so that the online fault monitoring of the optical network is completed.
(2) According to the scheme, for quality monitoring of the whole sensing optical fiber at a certain frequency point, accumulated signals of Rayleigh scattering along the whole sensing optical fiber are adopted, so that a higher signal-to-noise ratio can be obtained, and the online monitoring precision of the optical fiber quality is improved; by the modulation mode of the stepping frequency, the spatial domain resolution can be improved by increasing the stepping times, and the positioning precision of the line fault is improved.
(3) Compared with the OTDR measurement technology, the positioning resolution of the adopted incoherent optical frequency domain reflection measurement technology is only related to the optical frequency scanning bandwidth but not related to the optical power, so that the scheme of the disclosure can ensure that the positioning spatial resolution without difference can be obtained even under the long-distance optical fiber measurement condition.
(4) For the positioning resolution of 1m, the OTDR measurement technology needs a laser light source with light pulse less than 10ns and peak power up to several watts, while the light source used by the incoherent light frequency domain reflection measurement technology can be a frequency-modulated continuous light output laser light source with peak power of only hundreds of milliwatts, and has cost advantage; for the OTDR measurement technique with high positioning resolution, the requirement on the sampling frequency of the rayleigh scattering signal is high, and usually reaches the GHz level, but the incoherent optical frequency domain reflection measurement technique adopted by the scheme of the present disclosure has low requirement on the sampling rate due to the use of the mixer in the device, thereby reducing the complexity of the technique implementation.
Advantages of additional aspects of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
Fig. 1 is a structural diagram of an optical fiber fault monitoring device based on incoherent optical frequency domain reflection according to a first embodiment of the present disclosure;
fig. 2 is a block diagram of a receiver according to a first embodiment of the disclosure;
fig. 3 is a schematic diagram of spectrum information related to the health status of the entire optical fiber network according to the second embodiment of the present disclosure;
fig. 4 is a schematic diagram of spatial domain information of the optical network health status distributed along the sensing optical fiber according to the second embodiment of the present disclosure.
Detailed Description
The present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict.
Description of the terms:
incoherent optical frequency domain reflection technology:
an Incoherent Optical Frequency Domain Reflection (IOFDR) technology originally originated from a Frequency Modulated Continuous Wave (FMCW) lidar system, and mainly realizes distributed detection by detecting the Frequency response of backscattered light of an Optical fiber and then utilizing a Frequency Domain-spatial Domain transformation principle.
The microwave signal source outputs a linear frequency-sweeping output signal, the light source light-emitting is modulated through the electro-optic modulator, the linear frequency-sweeping output signal is emitted into the long-distance optical fiber after passing through the optical circulator, the reflected signal is then converged with the local oscillation signal at the frequency mixer, and the high-frequency signal after frequency mixing is filtered by the low-pass filter, so that the quality monitoring of the whole sensing optical fiber at a certain frequency point is realized. The optical frequency of the laser is changed to scan, so that the state information of the sensing optical fiber of each frequency point can be obtained, the state information related to the position of the sensing optical fiber can be obtained by means of inverse Fourier transform, and the online fault monitoring of the optical network is completed.
The first embodiment is as follows:
the embodiment aims to provide an optical fiber fault monitoring device based on incoherent optical frequency domain reflection.
An optical fiber fault monitoring device based on incoherent optical frequency domain reflection comprises a digital signal processor; the digital signal processor drives the direct digital frequency synthesizer to output two paths of signals through the control bus, one path of signal is input into the laser driver, and the laser driver drives the semiconductor laser to generate continuous light waves with step frequency modulation; the other path of signal is input into a receiver; the continuous light wave is input into a first port of the circulator and is emitted into the sensing optical fiber through a second port; rayleigh scattered light waves generated on the sensing optical fiber are emitted into the photoelectric detector through the third port, and the photoelectric detector converts the rayleigh scattered light waves into weak current signals and transmits the weak current signals to the receiver;
the receiver converts weak current signals related to Rayleigh scattering into digital signals, transmits the digital signals to the digital signal processor, and processes the digital signals through the digital signal processor to realize monitoring of optical fiber faults.
Specifically, for ease of understanding, the embodiments of the present disclosure are described in detail below with reference to the accompanying drawings:
the invention discloses a high-precision optical network on-line fault monitoring device and method of incoherent optical frequency domain reflection, wherein the device comprises: a Digital Signal Processor (DSP), a direct digital frequency synthesizer (DDS), a laser driver, a semiconductor laser, a circulator, a sensing optical fiber and a receiver;
the DSP drives the DDS through a control bus to enable the DDS to output a frequency range from f1To f2A continuous step frequency sweep signal with a frequency interval delta f and a step frequency number of N; wherein the cut-off frequency f2The modulation frequency bandwidth is determined to a great extent, the available positioning spatial resolution is further determined, the selection is usually 10 MHz-1 GHz, and the corresponding available positioning spatial resolution is 10-0.1 m; starting frequency f1Should be chosen to be significantly less than f2Guarantee that sufficient modulation bandwidth is obtained, but with f2Compared with the dynamic range, the difference cannot be too large, the signals with different frequencies are ensured to have proper power flatness, and the selection range can be 0.1-1 MHz.
The DDS outputs two paths of signals, and the 1 path outputs a continuous stepping frequency sweep frequency signal and is connected with a laser driver; the other 1 path of output frequency is always f1The single-frequency signal of (2) is connected with the receiver;
under the action of the DDS output signal, the laser driver outputs a continuous step frequency sweep frequency current signal which accords with the driving standard of a rear-stage semiconductor laser, and drives the semiconductor laser to generate continuous light waves with step frequency modulation;
the continuous light wave with the step frequency modulation enters a port 1 of the circulator, and then exits from a port 2 of the circulator to enter a sensing optical fiber;
in the process that the light waves propagate along the sensing optical fiber, Rayleigh scattering light waves carrying the optical network health state are generated and return to the port 2 of the circulator, and then the Rayleigh scattering light waves are emitted from the port 3 of the circulator and enter the photoelectric detector;
the photoelectric detector converts Rayleigh scattering light waves into weak current signals and transmits the weak current signals to the receiver;
the receiver converts the weak current signals related to Rayleigh scattering into digital signals and transmits the digital signals to the DSP;
the DSP can obtain frequency domain information related to the optical network health state according to the Rayleigh scattering signals of all frequency points of the stepping frequency, and can obtain information distributed along the space related to the optical network health state by utilizing inverse Fourier transform, thereby completing the high-reliability online monitoring of the optical communication system and the accurate positioning of line faults.
Further, as shown in fig. 2, the receiver is composed of a transimpedance amplifier, a mixer, a high-precision analog amplifier, and an analog-to-digital converter (ADC).
The trans-impedance amplifier converts a weak current signal output by the photoelectric detector into a voltage signal and outputs the voltage signal to a Radio Frequency (RF) input end of the mixer.
The mixer has two input ports, an RF input and a Local Oscillator (LO) input. The voltage signal related to Rayleigh scattering is input at the RF input end, and the frequency of the DDS output which is input at the LO input end is always f1A single frequency signal of (a). After mixing, the frequency range of the voltage signal is down-converted to 0 to f2-f1And output as an Intermediate Frequency (IF) signal to a high-precision analog amplifier.
The high-precision analog amplifier amplifies the voltage signal, so that the voltage range requirement of the rear-stage ADC on the input signal is met.
And the ADC converts the voltage signal into a digital signal and transmits the digital signal to the DSP.
Example two:
the embodiment aims to provide an optical fiber fault monitoring method based on incoherent optical frequency domain reflection.
An optical fiber fault monitoring method based on incoherent optical frequency domain reflection utilizes the optical fiber fault monitoring device based on incoherent optical frequency domain reflection, and comprises the following steps:
controlling a semiconductor laser to generate continuous light waves with step frequency modulation through a laser driver;
inputting the continuous light wave with the step frequency modulation into a sensing optical fiber, and generating Rayleigh scattering light waves related to the health state of an optical network;
aiming at Rayleigh scattering related electric signals returned by all frequency points of the stepping frequency, using a local oscillation clock with fixed frequency to carry out frequency mixing to obtain frequency domain information of the whole sensing optical fiber related to the health state of the optical network;
and performing Fourier inverse transformation on the frequency domain information to obtain spatial domain information of the optical network health state distributed along the sensing optical fiber, further obtaining fault information and position information along the measured optical fiber, and realizing monitoring of optical fiber faults.
Further, the health state of the optical network comprises fusion joints, bends and breakpoints of the optical fibers along the optical fiber.
Specifically, for ease of understanding, the method of the present disclosure is described in detail below with reference to fig. 3 and 4:
the invention discloses a device and a method for monitoring the online fault of a high-precision optical network reflected by an incoherent optical frequency domain, wherein the method comprises the following steps:
step 1: the semiconductor laser generates light waves with step frequency modulation; frequency modulation range from f11MHz to f2A continuous step frequency sweep signal with 10MHz frequency interval Δ f of 100kHz and step frequency number of 91. Wherein the cut-off frequency f2Determines the modulation frequency to a great extentThe rate bandwidth further determines the obtainable positioning spatial resolution, which is usually selected to be 10 MHz-1 GHz, and the corresponding obtainable positioning spatial resolution is 10-0.1 m; starting frequency f1Should be chosen to be significantly less than f2Guarantee that sufficient modulation bandwidth is obtained, but with f2Compared with the dynamic range, the difference cannot be too large, the signals with different frequencies are ensured to have proper power flatness, and the selection range can be 0.1-1 MHz. When f is1＝1MHz，f2At 10MHz, a positioning spatial resolution of 10m can be obtained.
The power of the modulated light wave when propagating in the optical fiber can be expressed as:
where z denotes the propagation distance and m denotes the modulation depth, typically m is less than 1, ωmRepresenting the modulation angular frequency of the laser, ranging from 2 pi f1To 2 pi f2The angular frequency interval is 2 pi delta f,
denotes the propagation constant, n, of a light wave in an optical fiberpDenotes the refractive index of the fiber, c denotes the speed of light in vacuum, αPRepresenting the loss factor of light waves propagating in the fiber.
It is clear that Pp(z，ωmT) is a positive real simple harmonic function, which can be rewritten as:
where Re (x) represents the real part of the complex number x.
Step 2: the light wave with the step frequency modulation is transmitted along the sensing optical fiber to generate Rayleigh scattering light waves related to the health state of the optical network.
The rayleigh scattered power obtained from a length dz of fiber is:
dPR(z，ωm，t)＝Pp(z，ωm，t)χR(s(z，t))dz (3)
wherein s (z, t) represents the measured information related to the health of the optical network, and is related to the position z and the time t of the optical fiber, and χR(s (z, t)) represents the fiber health dependence coefficient of Rayleigh scattering, and R represents Rayleigh scattering.
And step 3: when the health state of the sensing fiber along the line to be measured changes relatively slowly, which is less than the time of a single measurement, the health state of the optical network can be considered to be related to the spatial distribution only, and therefore the health state of the sensing fiber along the line can be represented as s (z).
The rayleigh scattering power of the optical fiber micro element with the length dz at the optical fiber position z detected by the photoelectric detector is as follows:
wherein alpha isRRepresents the loss coefficient, beta, of Rayleigh scattered light waves propagating in an optical fiberRRepresenting the propagation constant of the rayleigh scattered light wave in the optical fiber.
By integrating the above equation, the backward rayleigh scattering power of the entire sensing fiber with length L can be obtained:
in the above formula, the first term is a direct current term not dependent on the modulation frequency ωmChanges, and therefore does not carry information on the spatial distribution of the rayleigh scattering. The second term is an alternating term and the modulation frequency omegamIt is related. Can be rewritten as:
wherein the content of the first and second substances,
the Rayleigh scattering and loss information of the whole sensing optical fiber is contained.
And 4, step 4: aiming at the Rayleigh scattering related electric signals returned by all frequency points of the stepping frequency, the use frequency is f1The local oscillation clock is used for carrying out frequency mixing to obtain frequency domain information S related to the health state of the whole sensing optical fiber optical network with the frequency range of 0-9 MHz and the frequency interval of 100kHzR(ωm) As shown in fig. 3.
And 5: carrying out inverse Fourier transform on the frequency domain information of the whole sensing optical fiber optical network health state to obtain spatial domain information s of the optical network health state distributed along the sensing optical fiberRAnd (z), completing the high-reliability online monitoring of the optical communication system and the accurate positioning of the line fault, as shown in fig. 4.
The optical fiber fault monitoring device and method based on incoherent optical frequency domain reflection can be realized, and have wide application prospects.
The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Claims (10)
1. An optical fiber fault monitoring device based on incoherent optical frequency domain reflection is characterized by comprising a digital signal processor; the digital signal processor drives the direct digital frequency synthesizer to output two paths of signals through the control bus, one path of signal is input into the laser driver, and the laser driver drives the semiconductor laser to generate continuous light waves with step frequency modulation; the other path of signal is input into a receiver; the continuous light wave is input into a first port of the circulator and is emitted into the sensing optical fiber through a second port; rayleigh scattered light waves generated on the sensing optical fiber are emitted into the photoelectric detector through the third port, and the photoelectric detector converts the rayleigh scattered light waves into weak current signals and transmits the weak current signals to the receiver;
the receiver converts weak current signals related to Rayleigh scattering into digital signals, transmits the digital signals to the digital signal processor, and processes the digital signals through the digital signal processor to realize monitoring of optical fiber faults.
2. The fiber optic fault monitoring device based on incoherent optical frequency domain reflection as claimed in claim 1, wherein said digital signal processor processes said digital signal, specifically: obtaining frequency domain information related to the health state of the optical network according to the Rayleigh scattering signals of all frequency points of the stepping frequency; and carrying out inverse Fourier transform on the frequency domain information to obtain the information of the spatial distribution related to the health state of the optical network.
3. The fiber fault monitoring device based on incoherent optical frequency domain reflection according to claim 1, wherein the receiver converts the weak current signal related to rayleigh scattering into a digital signal, specifically: and aiming at Rayleigh scattering current signals returned by all frequency points of the stepping frequency, carrying out frequency mixing by using an oscillating clock with fixed frequency to obtain frequency domain information of the whole sensing optical fiber related to the health state of the optical network, and converting the frequency domain information into a digital signal.
4. The apparatus according to claim 1, wherein the digital signal processor drives the direct digital frequency synthesizer via the control bus to output two signals, one of which is a continuous step frequency sweep signal, and the other of which is a single frequency signal with a fixed frequency.
5. The apparatus according to claim 1, wherein the continuous wave is input to the first port of the circulator and is injected into the sensing fiber through the second port, and when propagating along the sensing fiber, the continuous wave generates rayleigh scattered waves carrying health status of the optical network and is injected into the photodetector through the third port.
6. The apparatus of claim 1, wherein the receiver comprises a transimpedance amplifier, a mixer, a high-precision analog amplifier, and an analog-to-digital converter connected in series.
7. The apparatus according to claim 1, wherein the transimpedance amplifier converts the weak current signal output by the photodetector into a voltage signal, and outputs the voltage signal to the rf input of the mixer.
8. A method for monitoring optical fiber fault based on incoherent optical frequency domain reflection, which is characterized in that the device for monitoring optical fiber fault based on incoherent optical frequency domain reflection as claimed in any one of claims 1 to 7 is utilized, and comprises the following steps:
controlling a semiconductor laser to generate continuous light waves with step frequency modulation through a laser driver;
inputting the continuous light wave with the step frequency modulation into a sensing optical fiber, and generating Rayleigh scattering light waves related to the health state of an optical network;
aiming at Rayleigh scattering related electric signals returned by all frequency points of the stepping frequency, using a local oscillation clock with fixed frequency to carry out frequency mixing to obtain frequency domain information of the whole sensing optical fiber related to the health state of the optical network;
and performing Fourier inverse transformation on the frequency domain information to obtain spatial domain information of the optical network health state distributed along the sensing optical fiber, further obtaining fault information and position information along the measured optical fiber, and realizing monitoring of optical fiber faults.
9. The method as claimed in claim 1, wherein the semiconductor laser is controlled by a laser driver to generate a continuous light wave with step frequency modulation, and the conducted power of the light wave is specifically expressed as follows:
where z denotes the propagation distance, m denotes the modulation depth, ωmWhich represents the angular frequency of modulation of the laser,
denotes the propagation constant, n, of a light wave in an optical fiberpDenotes the refractive index of the fiber, c denotes the speed of light in vacuum, αpRepresents the loss factor of the light wave propagating in the fiber, and re (x) represents the real part of the complex number x.
10. The fiber optic fault monitoring device based on incoherent optical frequency domain reflection as claimed in claim 1, wherein: obtaining the health state of the optical network comprises the fusion point, the bending and the breakpoint which appear along the optical fiber.
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| CN117572444B (en) * | 2024-01-17 | 2024-03-15 | 赛丽科技(苏州)有限公司 | Frequency modulation continuous wave laser radar ranging and speed measuring system and method |
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