207 results about "Fiber amplifier" patented technology

The invention belongs to the technical field of microwave photon links, and particularly relates to a high-resolution microwave photon frequency measurement system based on real-time Fourier transform. The link comprises a mode-locked laser, a first dispersion compensation module, a second dispersion compensation module, a dual-drive Mach-Zehnder modulator, a Mach-Zehnder modulator, a dispersion optical fiber, a time lens, an erbium-doped optical fiber amplifier, a photoelectric detector and an oscilloscope; the mode-locked laser outputs femtosecond Gaussian light pulses, and the femtosecond Gaussian light pulses are injected into the first dispersion compensation module and then stretched into chirp light pulses; modulating the chirp light pulse through electro-optical modulators which are connected in parallel; the modulated optical signal is subjected to time amplification processing through a dispersion optical fiber, a time lens, a second dispersion compensation module and an erbium-doped optical fiber amplifier in sequence; and the optical signal after time amplification processing is converted into a microwave pulse carrying frequency information of the signal to be detected by a photoelectric detector, and the microwave pulse is observed by an oscilloscope.

The present invention relates to a lidar system including: laser transmitter and receiver systems, the laser transmitter system including: a wavelength-tunable seed laser which emits pulses at selected wavelength points, and switches between wavelengths within a switching time of <200 ns; a fiber amplifier which amplifies the laser pulses up to 200 kW to a transmitter grating; and a transmitter telescope including primary and secondary mirrors. The laser beam is directed from the transmitter grating to the secondary then primary mirrors, and the first transmitter grating is imaged on the primary mirror to minimize laser beam wander thereon. The transmitter grating diffracts and steers the laser beam by wavelength to a surface, to an arbitrary subset of <2000 resolvable footprints along a cross-track direction at a beam pointing angle switching time of <200 ns, such that footprints illuminated by the laser beam on the surface are imaged in 3D.

The invention provides a satellite-borne EDFA on-orbit performance degradation monitoring method and system. The satellite-borne EDFA on-orbit performance degradation monitoring method comprises the steps that a health baseline is preset; closing input light and a first-stage pump of the satellite-borne EDFA; driving a second-stage pump of the satellite-borne EDFA to maintain fixed power output, and recording the working temperature of the second-stage pump; acquiring the monitoring optical power of the second-stage pump and the spontaneous radiation power of the output end of the satellite-borne EDFA; calculating to obtain spontaneous radiation conversion rate; and carrying out satellite-borne EDFA degradation determination. The method has the beneficial effects that the interference of temperature fluctuation on a monitoring result is greatly reduced through the spontaneous radiation conversion rate which is a relative parameter, and the method is adaptive to a complex thermal environment of a satellite; degradation is judged based on a preset health baseline, precise monitoring of the performance state of the satellite-borne EDFA is achieved, and a reliable basis is provided for maintenance. Precise positioning of a degraded part is realized, a fault source is clear, blind maintenance is avoided, and the maintenance efficiency is improved; monitoring can be completed in a second level and can be arranged to be carried out in a communication intermittent period, and normal communication service of the satellite is not affected.

The invention discloses a multi-core optical fiber amplifier with a large core-to-cladding ratio and a gain method. The multi-core optical fiber amplifier is characterized by comprising a multi-core optical fiber formed by a plurality of independent rare earth-doped fiber cores and a cladding structure located on the outer side of the multi-core optical fiber, the cladding structure is internally provided with at least one layer of low-refractive-index isolation region which is used for remarkably compressing the effective cladding area of pumping propagation and improving the capturing efficiency of the whole pumping energy, and the ratio of the total cross sectional area of the multi-core optical fiber to the effective cladding area is not less than 0.1. The low-refractive-index isolating layer is embedded in a conventional cladding structure, so that a pump light propagation area can be effectively compressed on an optical path, the relative proportion of the fiber core in the cross section is increased, the proportion (CCAR is larger than or equal to 0.1) of the total area of the fiber core to the cladding area is remarkably increased, and therefore the pump capture efficiency is improved.

The invention provides a C + L + S wave band multi-device configuration optimization method and device, and the method comprises the steps: calculating the approximate optimal transmission power of an optical fiber entrance part through employing a local optimal approximate global optimal algorithm; taking the approximate optimal transmitting power as the receiving power of each span section, and recalculating the transmitting signal power at the starting position of the span section by reversely solving a stimulated Raman scattering effect power evolution equation; the gain and gain slope of the optical fiber amplifier are set, so that the signal power which begins to be input in each span segment approaches the transmitting signal power; constructing a loss function based on the generalized signal-to-noise ratio of each wave band; and the gain and the gain slope set after inversion of the stimulated Raman scattering effect are used as initial values, and the gain and the gain slope of the optical fiber amplifier and the channel loss value of the wavelength selection switch are iteratively optimized by using a gradient rising algorithm and taking the loss function improvement as a target. According to the method provided by the invention, only a small amount of iteration is needed, the operation speed is high, and multi-device second-level configuration optimization of the broadband optical transmission system can be realized.

The invention provides an optical feedback resonance enhanced forward Brillouin demodulation structure, which comprises a tunable laser, a first polarization controller, an erbium-doped optical fiber amplifier, an optical coupler, an optical isolator, a forward Brillouin gain optical fiber, a band-pass filter and a photoelectric detector, a second polarization controller; and a spectrum analyzer. The first polarization controller is connected with a port a of the optical coupler, a port b of the optical coupler is connected with an input end of the erbium-doped optical fiber amplifier, an output end of the erbium-doped optical fiber amplifier is connected with the optical isolator, the optical isolator is connected with the band-pass filter, the band-pass filter is connected with the forward Brillouin gain optical fiber, and the optical fiber is fed back to a port c of the coupler through the second polarization controller. The output power of the erbium-doped optical fiber amplifier is controlled, and the polarization states of the pump light and the feedback laser are controlled by the first polarization controller and the second polarization controller, so that the forward Brillouin effect is amplified.

A pulse light generation device 1 comprises: an oscillator 2 for oscillating an ultrashort pulse light L; a stretcher fiber 7 for widening the time width of the ultrashort pulse light L; a fiber amplifier 8 for amplifying the ultrashort pulse light L the time width of which has been widened by the stretcher fiber 7; and a compressor 9 for compressing the time width of the ultrashort pulse light L which has been amplified by the fiber amplifier 8. The stretcher fiber 7 is configured by combining a first fiber 71 for widening the time width of the ultrashort pulse light L with a first characteristic, and a second fiber 72 for widening the time width of the ultrashort pulse light L with a second characteristic which is different from the first characteristic.

The application discloses a quantum random number generator based on feedback adjustment of a comparator threshold value and a random sequence generation method. The quantum random number generator comprises a superluminescent diode, a filter, an erbium-doped fiber amplifier, a fiber coupler with a coupling ratio of 50:50, an optical delay line, a first beam splitter and a second beam splitter with the same splitting ratio, a first optical power meter and a first photodetector connected with the first beam splitter, a second optical power meter and a second photodetector connected with the second beam splitter, a microcontroller connected with the first optical power meter and the second optical power meter, and a comparator connected with the microcontroller, the first photodetector and the second photodetector. The first photodetector and the second photodetector are connected with the comparator through a differential circuit. The application adjusts the threshold voltage to offset the influence of the output characteristics of a light source on the output random number.

The application discloses a device and method for coexistence of bright-dark solitons based on a mode division multiplexing resonant cavity, and relates to the technical field of lasers.The device for coexistence of bright-dark solitons based on the mode division multiplexing resonant cavity comprises an erbium-doped fiber amplifier, a first optical coupler, an acousto-optic frequency shifter, a second optical coupler, a third optical coupler, a first mode selection coupler, a second mode selection coupler and a fiber ring resonant cavity, and the fiber ring resonant cavity is a non-uniform dispersion few-mode fiber.The device and method for coexistence of bright-dark solitons based on the mode division multiplexing resonant cavity can realize stable coexistence of bright-dark solitons.

Disclosed is a pulsed laser apparatus and method of generating a laser pulse. The apparatus includes an input coupler configured to receive pumping light from a pumping light source and a seed pulse from a seed pulse generator. The apparatus further includes a doped fiber-optic cable with an input port at a first end configured to receive the pumping light and the seed pulse. The doped fiber-optic cable amplifies the seed pulse to generate an output pulse. Along a first length of the doped fiber optic cable, the pulse spectrum broadens rapidly owing to nonlinearity. Beyond the first length in an extended portion, the output pulse shifts towards longer wavelengths and broadens in both spectral and temporal domains. The apparatus also includes an output port at a second end of the doped fiber-optic cable, wherein the output pulse exits the doped fiber-optic cable at the output port.

By utilizing soliton self-frequency shift modulation, the formation of multiple pulsed light beams is suppressed, while the occurrence of ASE (Autonomous Emission Reduction) is suppressed, and the modulated pulsed light beam is reliably amplified. [Solution] The pulsed light generation device 100 comprises an oscillator 1 that oscillates pulsed light L, a fiber amplifier 2 located downstream of the oscillator 1 in the optical path of the pulsed light L, a soliton shift fiber 5 located downstream of the fiber amplifier 2 in the optical path of the pulsed light L, a branching section 8 located downstream of the fiber amplifier 2 in the optical path of the pulsed light L, and a short-wavelength fiber amplifier 11 located downstream of the soliton shift fiber 5 and the branching section 8 in the optical path of the pulsed light L.

To allow a wavelength variable light source and a wavelength variable method that can tune the wavelength of the output light to reliably amplify the light over a wide wavelength range.SOLUTION: A wavelength variable light source 1 includes an optical output unit that outputs ultrashort pulsed light L and can variably change the wavelength of the output ultrashort pulsed light L, a second fiber amplifier 7 that amplifies the ultrashort pulsed light L output from the optical output unit, a filter 8 that filters the ultrashort pulsed light L amplified by the second fiber amplifier 7, and a third fiber amplifier 9 that amplifies the ultrashort pulsed light L filtered by the filter 8. The second fiber amplifier 7 has a higher gain on the short wavelength side than on the long wavelength side. The third fiber amplifier 9 has a higher gain on the long wavelength side than on the short wavelength side. The filter 8 attenuates the amplified spontaneous emission light.SELECTED DRAWING: Figure 1

This invention relates to an image processing-based phase-sensitive optical time-domain reflectometer and signal demodulation method and system, comprising: a laser, an electro-optic modulator, an arbitrary function generator, a first circulator, a filter, a first erbium-doped fiber amplifier, a bandpass filter, a semiconductor optical amplifier, a second erbium-doped fiber amplifier, a second circulator, an optical fiber under test, a photodetector, and a data acquisition card. The method of this invention facilitates high-precision demodulation over a wide range of strain or temperature conditions with high spatial resolution. This method combines image block matching and image denoising. Image block matching utilizes multiple frequency and spatial location information, improving demodulation accuracy when strain or temperature changes are large and helping to expand the measurement range. The image denoising method denoises the matched function image, reducing random noise in the system and improving demodulation accuracy at high spatial resolution.

A fiber amplifier to amplify seed light has a laser diode, an optical fiber segment, and a doped fiber. The laser diode generates pump light at a pump wavelength from an end facet, and optical fiber segment in optical communication with the pump light has a fiber Bragg grating (FBG) configured to lock the pump light from the end facets to the pump wavelength. The pump light from the laser diode interact with an active dopant of the doped fiber and can thereby amplifies the seed light. To provide less coherent light and improve stability of the laser diode over operation conditions, variations in refractive index in the FBG have a chirped period changing linearly along a length of the FBG. The chirped period shifts the reflectivity asymmetrically from a central wavelength region of the FBG, such as blue-shifting the reflectivity for a short wavelength.

The application discloses a kind of based on functional echo wall mode optical microbottle cavity Full light tuning controllable optical comb generation method. Including 1550nm narrow line width continuous wave laser, single-mode optical fiber, erbium-doped fiber amplifier, polarization controller, optical isolator, functional microbottle cavity-fiber taper coupling system, optical attenuator, optical spectrum analyzer and 1550nm power adjustable laser. The unique axial characteristics of echo wall mode microbottle cavity are used, the free spectral range of microcavity is reduced, the axial mode microcavity optical frequency comb with small free spectral range is generated, and based on full light tuning method, functional microbottle cavity is prepared, and the axial mode microcavity optical frequency comb generated is tuned by photo-thermal material titanium dioxide, and significant spectral range tuning is realized. The application solves the limitation that WGM microcavity optical frequency comb cannot be effectively tuned due to large free spectral range, and helps the practical application in the field of microcavity optical frequency comb optical communication, optical frequency synthesis and the like.

This invention belongs to the field of fiber lasers, specifically relating to an SBS suppression module, a fiber main amplifier, and a high-power narrow-linewidth laser. The SBS suppression module includes a polarization beam combiner and a 1×2 optical switch; the fiber main amplifier consists of a double-clad gain fiber, the SBS suppression module, and accompanying passive fiber devices; the high-power narrow-linewidth laser is composed of a narrow-linewidth laser seed source, a fiber preamplifier, and a fiber main amplifier connected sequentially, with the fiber preamplifier consisting of three stages of single-clad fiber amplifiers. The SBS suppression module effectively suppresses SBS, and its simple structure facilitates packaging. This invention enables narrow-linewidth fiber laser output with high beam quality at the 5kW level and above, and employs all-fiber fusion splicing technology to construct an all-fiber system, offering advantages such as compact and simple structure, good stability, increased power, and low cost.

The application relates to a polarization maintaining fiber amplifier, in particular to a single-fiber reflection type polarization maintaining fiber amplifier, which comprises a polarization beam splitter PBS, a first Faraday optical rotator, a second Faraday optical rotator, an input polarization maintaining fiber collimator, a first polarization maintaining fiber collimator, a second polarization maintaining fiber collimator and a gain amplification unit, the input polarization maintaining fiber collimator is connected with an input polarization maintaining fiber, the input polarization maintaining fiber collimator is aligned with port 3 of the polarization beam splitter PBS, and a first Faraday optical rotator is arranged between the input polarization maintaining fiber collimator and the port 3 of the polarization beam splitter PBS; port 1 of the polarization beam splitter PBS is aligned with the first polarization maintaining fiber collimator, the first polarization maintaining fiber collimator is connected with an input end of the gain amplification unit, and an output end of the gain amplification unit is connected with the second polarization maintaining fiber collimator; the technical scheme can effectively overcome the defect that the optical signal cannot be amplified and returned along the same optical fiber in the prior art.

The application discloses a kind of rock mechanics test in the collection device of acoustic emission signal, including computer, measurement and control and signal processing equipment, distributed acoustic wave sensing equipment and collection probe: the collection probe is composed of single-mode optical fiber and probe skeleton, single-mode optical fiber is fixed around probe skeleton, when testing, collection probe is fixed on the surface of rock sample for testing;The measurement and control and signal processing equipment include: radio frequency amplifier, digital-to-analog conversion module, analog-to-digital conversion module, filter amplifier, field programmable logic gate array and CPU-GPU data processing module;The distributed acoustic sensing equipment includes narrow linewidth laser, fiber coupler, acoustooptic modulator, erbium-doped fiber amplifier, circulator, polarization diversity receiver, first balanced photodetector and second balanced photodetector;Collection signal band is wide, can be conveniently installed on any rock sample.Collecting main frequency is lower, collection probe is connected closely with rock sample, coupling is good, without additional smearing coupling agent.

This invention proposes a random microwave pulse generation system and method based on an optoelectronic oscillator, belonging to the field of microwave photonic signal generation and processing technology. The system includes a laser, a polarization controller, a closed-loop optoelectronic oscillator (OEO) loop, a random fiber grating string, and a function generator; wherein the closed-loop optoelectronic oscillator (OEO) loop mainly consists of a Mach-Zehnder modulator, a circulator, an erbium-doped fiber amplifier, a photodetector, an electrical amplifier, and a directional coupler.

A temperature strain separable dynamic and static combined measurement distributed optical fiber sensing system, comprising: laser, optical modulator, radio frequency signal generator, optical filter, DFB laser, polarization controller, first acoustooptic modulator, depolarizer, erbium-doped fiber amplifier, two optical circulators, optical wavelength division multiplexer, receiving module, signal acquisition and processing module are arranged in sequence, the application carries out temperature sensing to the back Raman scattering light of the pulse while receiving the Rayleigh scattering light of the detection pulse, and controls the time interval of adjacent pump pulse and detection pulse to carry out three-bit pulse coding and decoding, so that the back Raman scattering signals of individual pulse in pulse pair are separated in time, and finally the simultaneous measurement of dynamic variable (vibration) and static variable (temperature, static strain) is realized and the spatial resolution of measurement is ensured not to be lost.

This invention discloses a digital holographic 3D reconstruction system and method based on a single-cavity dual-optical comb, belonging to the field of digital holographic 3D measurement technology. The invention includes: a single-cavity dual-optical comb, a coarse wavelength division multiplexer, a first fiber amplifier, a second fiber amplifier, a first fiber filter, a second fiber filter, a first fiber beam expander, a concave mirror, a second fiber beam expander, a beam splitter, an image sensor, and a computer. The single-cavity dual-optical comb emits two pulses, which are split, amplified, and filtered. The measurement light and the reference light produce interference fringes, forming a hologram. This invention uses a single-cavity dual-optical comb as a light source to achieve the separation of the zero-order image, twin image, and target re-phenomenon in coaxial holography, improving the quality of holographic imaging and facilitating engineering implementation. Based on multi-wavelength heterodyne technology, combined with the wide spectral bandwidth and high temporal coherence of the optical comb, this invention suppresses the influence of noise, enabling the measurement of large-size objects and expanding the application scenarios of digital holography.

The invention relates to the technical field of optical fiber amplifiers, and discloses a main and backup optical fiber amplifier structure and a preparation method.The amplifier structure comprises a shell, a beam splitter, a main optical fiber amplification light path and a backup optical fiber amplification light path, the shell comprises a bottom plate and a side wall, the main optical fiber amplification light path at least comprises a main optical fiber, and the backup optical fiber amplification light path at least comprises a backup optical fiber; the backup optical fiber amplification optical path at least comprises a backup optical fiber, the beam splitter is connected with the main optical fiber amplification optical path and the backup optical fiber amplification optical path, an annular groove is formed in the lower surface of the bottom plate, an annular partition plate is formed in the corresponding position of the annular groove in the upper surface of the bottom plate, and the main optical fiber is wound in the annular groove; the backup optical fiber is wound around the outer side of the annular partition plate, and the main optical fiber and the backup optical fiber are physically separated through the annular partition plate. According to the technical scheme provided by the invention, the redundancy and robustness of the main and backup optical fiber amplifiers can be improved.

The application provides a device and a method for realizing PON rate adjustment based on Polar modulation, and relates to the technical field of passive optical networks.The device comprises a first external cavity laser, a second external cavity laser, a dual-polarization phase quadrature modulator, an arbitrary waveform generator, an erbium-doped fiber amplifier, a single-mode optical fiber, a variable optical attenuator, a coherent receiver and an oscilloscope.The method comprises the following steps: dynamically adjusting the number of information bits A, splicing check bits to form total information bits, optimizing the distribution of information bits and frozen bits according to the optical signal channel sorting result, performing polar encoding on the signal at the encoding end, and mapping the signal into a 16QAM code symbol sequence by using the Polar modulation technology; at the receiving end, calculating the LLR, calculating the path metric value of all paths and performing a pruning operation when the list width reaches a set value, and detecting the L candidate paths by using the CRC check after the decoding is completed.The application realizes flexible regulation and control of the transmission rate of different optical network units.

An optical amplifying device based upon the use of Tm-doped optical fiber is proposed, and particularly configured to provide amplification of input signals operating in the wavelength range of 1700-1800 nm. A section of Tm-doped fiber less than a meter is used to provide amplification in the proposed wavelength range, and the amplifying device is specifically configured to direct unabsorbed pump energy away from the main signal path of the amplifying device, preventing damage to and / or degradations in the performance of the amplifying device.

The invention belongs to the technical field of lasers. The invention provides an all-fiber laser with adjustable pulse width and a pulse width tuning method. The all-fiber laser comprises a narrow-band dissipation soliton mode-locked fiber laser seed source, a first fiber isolator, a fiber amplifier, a second fiber isolator, an optical circulator and a dispersion element which are sequentially arranged along a light path. The seed source generates a mode-locked pulse with a fixed initial spectral width; the nonlinear effect intensity is controlled by adjusting the driving current of the pumping source, so that the spectrum broadening amount of the pulse in the amplification process is regulated and controlled, the variable total spectrum width is formed, the spectrum width is subjected to linear time-frequency mapping through a dispersion element with a fixed group delay dispersion value, and finally continuous and electric control adjustment of the output pulse width is achieved. The whole system adopts an all-fiber structure, has the advantages of high stability, compact structure, good tuning linearity and the like, and is suitable for industrial processing, sensing and scientific research application scenes needing flexible pulse width regulation and control.

The application discloses an optical frequency comb automatic recovery device and method, and belongs to the field of silicon-based nonlinear optical photoelectric modulation. The application comprises a laser, an IQ modulator, an acousto-optic modulator, a fiber amplifier, a polarization controller, a micro-ring resonator, a phase-locked loop, an arbitrary waveform generator, a photoelectric detector, a PID module and an upper computer. Transmission loss of an optical frequency comb debugging system is tested, which comprises fiber loss before laser enters a microcavity and transmission loss after the laser enters the microcavity; the output frequency range of the phase-locked loop is adjusted, and frequency scanning is performed on the microcavity; laser wavelength is entered from blue detuning, the output power of the laser is gradually reduced through the acousto-optic modulator, and the wavelength is kept unchanged; when the PID detects a power rise, the laser power is quickly raised until the PID detects a rising step; the laser frequency is slowly increased and the power is kept unchanged until a single soliton optical frequency comb is observed; when the single soliton disappears, the control steps after the laser wavelength is entered from blue detuning are repeated, and the optical frequency comb is automatically recovered.

The invention discloses a 2-micron short-period laser amplifier based on a thulium-doped positive dispersion fluorotellurite optical fiber, which can solve the problem that a negative dispersion thulium-doped optical fiber is not suitable for performing gain management nonlinear amplification on a 2-micron pulse, and can obtain a pulse width lt. 50 fs, and single pulse energy gt; the femtosecond laser output device has the advantages of being full-fibrillated and compact in structure. The 2-micron femtosecond seed source is femtosecond pulse laser of a 2-micron wave band generated based on nonlinear amplification loop mirror mode locking; the chirped pulse amplifier is used for obtaining sub-picosecond 1.9 mu m femtosecond laser output with the average power greater than or equal to 1W; the optical fiber GMN amplifier is used for obtaining a few-period femtosecond pulse; the high-power optical fiber pulse compressor is a hollow-core optical fiber and is used for carrying out accurate dispersion compensation and high-quality pulse compression.

The invention belongs to the technical field of temperature control equipment, and particularly relates to a one-source two-channel intelligent modulation frequency doubling light system based on an ILTA-EDFA-IQ-PPLN integrated architecture, which comprises a light path execution subsystem, a light path control subsystem, a light path control subsystem and a light path control subsystem, the device comprises a narrow linewidth laser, at least one erbium-doped optical fiber amplifier, at least one IQ orthogonal optical signal modulator, at least one periodically poled lithium niobate nonlinear frequency doubling device and a plurality of optical splitters, and is used for generating and regulating the conversion from 1560nm-waveband laser to 780nm-waveband laser; according to the invention, through a'one-source dual-channel 'topological design, high-stability narrow-linewidth laser and high-power adjustable laser are provided at the same time, and the function flexibility of the system is improved. According to the design, the system can adapt to multi-scene requirements in atom detection, such as cold atom interference, atom cooling capture and atom excitation detection, and multiple sets of laser systems do not need to be additionally configured, so that the use cost and complexity are reduced.

The invention discloses a multimode cladding pumping resonance space division multiplexing optical fiber amplifier and an implementation method thereof, and relates to the technical field of optical fiber amplifiers. The multimode cladding pumping resonance space division multiplexing optical fiber amplifier comprises a transmission optical fiber, an active optical fiber, a multimode pumping optical fiber and a resonant cavity; the active optical fiber is one of a multimode optical fiber, a multi-core optical fiber and a multi-core multimode optical fiber and is used for realizing stimulated radiation amplification of multichannel signal light; the multi-mode pumping optical fiber is coupled with the active optical fiber through a pumping coupling assembly to form a pumping injection path which is used for accessing an external multi-mode pumping source and injecting pumping light into a cladding of the active optical fiber; by constructing a resonant light path for pumping recycling, residual pumping is converted into reusable effective pumping, so that the residual pumping participates in the pumping effect on the active section for multiple times in the system, the equivalent pumping intensity and the accumulative absorption amount of the active section are improved under the condition that the rated power of an external pumping source is not remarkably increased, and the energy consumption of the active section is reduced. The purposes of improving the gain efficiency and reducing the thermal load are achieved.

The invention provides an oil and gas pipeline hydrate generation monitoring system and method based on a phi-OTDR, and belongs to the technical field of pipeline natural gas monitoring. Comprising an external cavity laser, a coupler, an acousto-optic modulator, a first erbium-doped amplifier, a circulator, a to-be-detected optical fiber, a to-be-detected pipeline, a second erbium-doped amplifier, an attenuator, a frequency mixer, an optical detector, a low-pass filter, a data acquisition card and an upper computer. The external cavity laser is connected with the coupler, the coupler is connected with the acousto-optic modulator, the acousto-optic modulator is connected with the first bait-doped amplifier, the first bait-doped amplifier is connected with the circulator, the optical fiber to be measured is tightly laid on the outer wall of a pipeline to be measured, a port of the circulator is connected with the end of the optical fiber to be measured, and the circulator is connected with the second bait-doped amplifier. The second erbium-doped amplifier is connected with the attenuator, the attenuator is connected with the frequency mixer, the frequency mixer is connected with the coupler and the optical detector, the optical detector is connected with the low-pass filter, the low-pass filter is connected with the data acquisition card, and the data acquisition card is connected with the upper computer.