278 results about "Optical fibre amplifiers" patented technology

The invention discloses a multi-sideband chirp modulation DAS system and a working method thereof, and relates to the technical field of distributed sound wave sensing. The DAS system comprises a narrow linewidth laser, an optical fiber coupler, a phase modulator, an electro-optical modulator, an erbium-doped optical fiber amplifier, an optical fiber circulator, a dense wavelength division multiplexer, a photoelectric balance detector, a data acquisition card, an arbitrary waveform generator, a direct current source and the like. The phase modulator is used for modulating constant-amplitude multi-frequency continuous light, the frequency number of light waves is related to the harmonic number of a microwave modulation signal, the frequency interval is determined by the fundamental frequency of the microwave modulation signal, the continuous light frequency can be flexibly modulated by adjusting the microwave modulation signal, and the modulation bandwidth is large; detected beat frequency signals are compressed into single-frequency signals through pulses, phase information of the single-frequency signals is demodulated, vibration signals along the sensing optical fiber can be detected, the spatial resolution of the system depends on the chirp frequency sweeping range, and the spatial resolution is high.

The invention relates to the technical field of optical fiber monitoring and maintenance, and discloses an optical fiber monitoring method, device and equipment, a storage medium and a computer program product, and the method comprises the steps: enabling pulse light of a preset period to be coupled into a to-be-detected low-loss optical fiber based on an optical fiber amplifier and a variable optical attenuator, and generating a backward scattering light signal; converting the backward scattering light signal into an electric pulse signal by using a single-photon detector, and counting the electric pulse signal by using a preset period as a period through a synchronous clock to obtain a counting result; adjusting the power of the variable optical attenuator according to a counting result, and drawing a target signal curve of the to-be-measured low-loss optical fiber based on an adjustment result; and analyzing the target signal curve to obtain a monitoring result of the to-be-measured low-loss optical fiber. The power is dynamically adjusted in different measurement sections, and the multi-section measurement results are superposed, so that the dynamic range of the single-photon optical time domain reflectometer is remarkably expanded, and the loss and dead pixels of the low-loss optical fiber can be reflected more comprehensively and accurately.

The invention discloses a polarization-state-based optical fiber vibration sensing system and application, and relates to the technical field of optical fiber sensing, and the polarization-state-based optical fiber vibration sensing system mainly comprises a transmitting end and a receiving end. The transmitting end comprises a laser diode, a first erbium-doped optical fiber amplifier, a first circulator, a polarization scrambler, a single-mode optical fiber link, a second circulator and a second erbium-doped optical fiber amplifier which are connected in sequence; and the receiving end comprises a polarization beam splitter, a first shunt module, a second shunt module, an optical mixer, a first balanced photoelectric detector, a second balanced photoelectric detector, a third balanced photoelectric detector and a polarization analysis module. According to the optical fiber vibration sensing system based on the polarization state and the application, the vibration monitoring performance and reliability in a long-distance and high-noise environment can be improved.

The invention discloses a variable beam divergence angle laser communication terminal and a rapid capturing method thereof, and belongs to the technical field of optical communication equipment. Comprising a main telescope, a fine tracking fast reflecting mirror, a beam splitter, an optical filter, a beam splitter, a beacon receiving lens group, a beacon detector, a signal transmitting lens group, an advanced aiming fast reflecting mirror, a signal receiving lens group, a receiving optical fiber amplifier, a multi-core optical fiber splitter, an optical switch and a transmitting optical fiber amplifier, a signal light emitting light path, a beacon light receiving light path and a signal light receiving light path are formed; the signal light emission light path provides emission light beams through different mode field optical fibers and performs shaping and variable beam divergence angle emission on the emission light by using different paths of an emission mirror group, and the signal light receiving light path is used for completing collection, shaping, coupling and light amplification on input signal light. And the beacon light receiving optical path is used for collecting, shaping and converging the input signal light, and positioning a target light spot by using an image positioning detector. According to the invention, the remote capturing efficiency can be improved.

The invention discloses a control method and system of a high-power optical fiber amplifier, and relates to the technical field of optical fiber amplifiers, and the high-power optical fiber amplifier comprises a first-stage gain unit and a second-stage gain unit which are sequentially arranged along the transmission direction of light; the control method of the high-power optical fiber amplifier comprises the following steps: starting the high-power optical fiber amplifier according to a starting sequence of firstly starting a first-stage gain unit and then starting a second-stage gain unit; and closing the high-power optical fiber amplifier according to a closing sequence of firstly closing the second-stage gain unit and then closing the first-stage gain unit. According to the control method and system, the optical fiber amplifier can be controlled to realize relatively high power output, so that the optical fiber amplifier is suitable for being applied to a hollow-core optical fiber transmission system, the high-power optical fiber amplifier can be prevented from generating a huge reverse ASE signal to burn an optical path device under the condition of no input optical signal, and the application safety and reliability of the optical fiber amplifier are improved.

The invention provides a diaphragm type optical fiber liquid level sensing demodulation device and method based on a microwave photon technology, and the device comprises a broadband light source, a circulator, a diaphragm type optical fiber liquid level sensor, an erbium-doped optical fiber amplifier, a polarization controller, a DC power supply, a radio frequency source, an electro-optical modulator, a dispersion compensation optical fiber, a photoelectric detector and a power meter. The broadband light source is connected with a first port of the circulator, a second port of the circulator is connected with the diaphragm type optical fiber liquid level sensor, a third port of the circulator is connected with the erbium-doped optical fiber amplifier, the erbium-doped optical fiber amplifier is connected with the polarization controller, and the polarization controller is connected with the input end of the electrooptical modulator. The radio frequency source is connected with the modulation input of the electro-optical modulator, the direct current power supply is connected with the bias voltage input of the electro-optical modulator, the output of the electro-optical modulator is connected with the photoelectric detector through the dispersion compensation optical fiber, and the photoelectric detector is connected with the power meter, so that the measurement range is expanded while the sensing sensitivity and the resolution ratio are improved.

The utility model relates to a high-capacity wavelength division multiplexing fiber bragg grating sensing system in the field of fiber sensing. The high-capacity wavelength division multiplexing fiber bragg grating sensing system comprises a mode-locked fiber laser, a spectrum expansion module, a three-port optical circulator, a fiber bragg grating array, a dispersion module, a photoelectric detector, a data acquisition module and a data processing module. The spectrum expansion module is composed of an optical fiber amplifier, a nonlinear element and a polarization controller; the optical fiber amplifier is composed of an optical isolator, an erbium-doped optical fiber, a wavelength division multiplexer and a pump light source. According to the sensing system, the dispersion Fourier transform technology is applied, the offset of the center wavelength of the fiber bragg grating is mapped into the offset of time delay between time domain reflected light pulses, and the demodulation rate and precision of the fiber bragg grating sensing system are improved; and by adding a spectrum expansion module, the spectrum of pulse data output by the light source laser is expanded into a super-continuum spectrum by using a nonlinear effect, and the simultaneous measurement of hundreds of fiber bragg grating sensors can be theoretically supported.

The invention provides a BOTDR (Brillouin optical time domain reflectometry) system fusing Stokes-anti-Stokes light and a demodulation method, and belongs to the technical field of Brillouin distributed optical fiber sensing. The narrow linewidth laser is used for generating continuous optical signals; the input end of the coupler is connected with the laser, and the output end is connected with the pulse light branch and the local oscillator light branch. The pulsed light branch comprises a semiconductor optical amplifier, a random scrambler, a first erbium-doped optical fiber amplifier and a circulator which are connected in sequence; the local oscillator light branch comprises an electro-optical modulator, and the electro-optical modulator regulates and controls sideband frequency through a microwave module; the second erbium-doped optical fiber amplifier is used for extracting the Stokes light and the anti-Stokes light; the single-mode coupler mixes the double-sideband local oscillator light with the anti-Stokes light and the Stokes light; and the electrical beat frequency signals are acquired, filtered and enveloped and demodulated through an acquisition card. The detection capability of the Brillouin scattering signal is enhanced, the system structure is simplified, and the hardware cost and the maintenance difficulty are reduced.

A homodyne detection Doppler wind measurement laser radar device based on a silicon optical chip comprises a light source module, a photoelectron chip module, a semiconductor optical amplifier, an erbium-doped optical fiber amplifier, an optical circulator, an optical transceiver antenna, a transimpedance amplifier processing module, an A / D acquisition card module, a digital signal processing module and a display and storage module. Discrete devices such as a beam splitter, a frequency mixer and a detector in an optical fiber link are integrated on one chip, high-density integration with other components is carried out through the photoelectric hybrid packaging technology, and chipping and miniaturization of the all-optical-fiber wind finding radar are achieved. The semiconductor optical amplifier (SOA) is used for chopping, a homodyne detection method is used for eliminating the requirement for frequency shift, and compared with a traditional Doppler wind measurement laser radar, the Doppler wind measurement laser radar has the advantages of being small in power consumption, small in size, light in weight, high in integration level, convenient to produce in a large scale, low in cost of a single device and the like.

The invention discloses a 980nm-waveband ytterbium-doped fiber laser with expandable power and high beam quality. The 980nm-waveband ytterbium-doped fiber laser is composed of a single-mode seed source, a K-level fiber amplifier and an output coupling end. The single-mode seed source adopts an optical fiber oscillator and is composed of a first gain optical fiber, a first pumping signal beam combiner, a first pumping module, a first cladding light filter, a second cladding light filter, a high-reflectivity optical fiber grating, a low-reflectivity optical fiber grating, a first filter and a mode field adapter. The K-stage optical fiber amplifier is composed of K single-stage optical fiber amplifiers and K-1 filters, and except the last single-stage optical fiber amplifier, the output end of each single-stage optical fiber amplifier is connected with one filter. Each of the K single-stage optical fiber amplifiers comprises a section of gain optical fiber, two pumping signal beam combiners, two pumping modules and two cladding light filters, and the gain optical fiber is a step double-cladding ytterbium-doped optical fiber. According to the invention, high beam quality output can be ensured, and the total output power can be improved.

The invention discloses a system for simultaneously measuring temperature and pressure based on forward Brillouin scattering in a multi-core optical fiber, which relates to the technical field of optical fiber temperature and pressure double-parameter sensors, and is characterized in that light emitted by a pump light source enters a polarization controller after being modulated by a pump light modulation system, and then enters an erbium-doped optical fiber amplifier; one part is injected into a Sagnac ring, and the other part excites a high-order torsion-radial mode through a multi-core optical fiber; light emitted by the detection light source is divided into light beams transmitted in the clockwise direction and the anticlockwise direction through the coupler, and the light beams are injected into the Sagnac ring; the spectrum analyzer captures the frequency shift of the Brillouin scattering signal; the signal processing unit processes the frequency shift of the Brillouin scattering signal and inverts temperature and strain data; and the data analysis and feedback system is combined with machine learning to optimize temperature and strain data. According to the invention, high-sensitivity temperature and strain sensing is realized.

The application provides an optical fiber filter and an optical fiber amplifier, which can realize flat amplification of a few-mode optical signal, and can realize controllable adjustment of optical power of each optical signal mode in a plurality of optical signal modes transmitted by a fiber core of the optical fiber filter. The optical fiber filter comprises a fiber core, an inner cladding and an outer cladding, the refractive index of the fiber core, the refractive index of the inner cladding and the refractive index of the outer cladding are sequentially decreased, the fiber core is used for transmitting at least two different first optical signal modes, the inner cladding is used for transmitting at least two different second optical signal modes, and the fiber core is etched with at least one fiber grating; at least part of optical power of a target first optical signal mode is only coupled with a target second optical signal mode at the fiber grating, wherein the target first optical signal mode is one of the at least two first optical signal modes, and the target second optical signal mode is one of the at least two second optical signal modes.

The invention relates to the technical field of optical communication, in particular to a steady-state control method and device of an optical fiber amplifier, control over a plurality of pump lasers in an erbium-doped fiber amplifier (EDFA) is achieved in a mode of combining feed-forward control and feedback control, and the feed-forward control is used for obtaining initial pump current; according to feedback control, proportional integral differential calculation is carried out on an input and output optical power difference value to obtain a pump current correction amount; carrying out transient detection on the input optical power, correcting a proportional integral differential coefficient when the transient state occurs, and obtaining a pump current correction amount through a corrected proportional integral differential algorithm so as to obtain a master pump driving current; by distinguishing the transient effect of the input optical power and the judgment of the jitter of the input optical power, the requirement that the output optical power needs to be stably controlled when the transient state of the input optical power and the jitter of the input optical power occur is well met, and the defects that the transient index is poor and the jitter is poor are overcome. And meanwhile, the situation that the jitter of the output optical power is aggravated due to the jitter of the input optical power is inhibited.

The invention relates to the technical field of optical communication, in particular to a front optical fiber amplifier with a power balancing function. On the basis of a traditional Er-doped optical fiber amplifier, incident light is divided into a signal link and a competition link through a light splitting device with a fixed proportion. The purpose of introducing the competitive link is to generate a competitive wavelength which has an obvious competitive effect with the signal light in the EDF, and gain competition is carried out in the amplification process of the signal light in the EDF; wherein the competitive link finishes conversion from signal light wavelength to wavelength with obvious competitive effect by adopting a four-wave mixing principle based on HNLF, and then reversely inputs the converted competitive light into the EDF of the signal link to carry out a light amplification process with gain competition, so that the aim of reducing the output power fluctuation range after the signal light is amplified by the EDF is fulfilled.

The invention relates to the technical field of optical communication, in particular to a real-time monitoring protection circuit and method for a high-power optical fiber amplifier, and the circuit comprises at least one monitoring module and a processing module. And the processing module judges whether the optical power value reaches a threshold value or a target signal power set value in optical path design and judges whether the optical power value meets system requirements, if the optical power value does not meet the system requirements, an enable signal is output, and a pump laser in a post-stage second amplification module is enabled to be closed, so that the security control of the post-stage pump laser is realized. The damage to the active optical fiber of the key part in the high-power optical fiber amplifier caused by manual misoperation, optical path function failure or sudden failure of a monitoring device can be effectively prevented.

A cable discharge optical fiber detection sensor belongs to the technical field of optical fiber sensing and comprises a light source, a single-mode optical fiber, an acoustic optical modulator, an erbium-doped optical fiber amplifier, a beam splitter, a circulator, a beam combiner, a photodiode, a data processor and an optical fiber cable. The positive magnetostriction annular optical fiber and the negative magnetostriction annular optical fiber are arranged on the two sides of the high-voltage cable respectively, and the cable sheath is arranged outside the high-voltage cable. The technical scheme of the invention not only overcomes the limitation of the traditional discharge detection method, but also provides a novel sensor which is high in sensitivity, strong in anti-interference capability and easy to deploy in a distributed manner for the safety monitoring of the high-voltage cable, and has important engineering application value.

The invention discloses a circuit breaker plum blossom contact contact stroke intelligent detection method and system, and the method comprises the steps: a configuration step: a static contact is configured with an optical fiber sensing array, an image collection module and a light supplement module, the optical fiber sensing array comprises an optical fiber sensor, the optical fiber sensor comprises an optical fiber probe, and a matched optical fiber cable and an optical fiber amplifier, the image acquisition module comprises an industrial camera; a dynamic detection step: comprehensively scheduling an optical fiber sensor and an industrial camera, and collecting displacement data of a contact piece of the moving contact and connection state data of the closed moving contact and static contact in real time; a data processing step: fusing the displacement data of the optical fiber sensor and the image data of the industrial camera, evaluating the contact state and surface defects of the static contact and the moving contact, embedding a lightweight AI reasoning chip to carry out localization real-time processing, and adopting a contact wear compensation algorithm to carry out real-time processing on the basis of the contact closing times and historical wear data. Dynamically adjusting the detection threshold value of the optical fiber probe and the parameters of the contact state evaluation model.

The invention discloses a parameter determination method, device and equipment for a distributed Raman optical fiber amplifier and a medium, and the method comprises the steps: determining an optimization objective function of link tail end power configuration of each wavelength channel based on a target application scene of an optical fiber sensing integrated system; solving the optimization objective function by using a simulated annealing algorithm to obtain the optimal link end power configuration of each wavelength channel; and obtaining the target pumping power of each pumping source in the distributed Raman optical fiber amplifier by using a pre-trained neural network model according to the incident fiber optical power of each wavelength channel and the optimal link end power configuration. According to the invention, different requirements of communication and sensing can be met at the same time, and the communication and sensing fusion gain is maximized.

The invention discloses an optical fiber mine magnetic detection sensor and system based on a magnetic composite sheath and an FPI, and belongs to the technical field of optical fiber sensing and mineral resource detection. The magnetic composite sheath optical fiber sensor comprises an optical fiber core, a Fabry-Perot interference cavity inscribed in the fiber core, a wrapping layer wrapping the outer side of the fiber core, a coating layer wrapping the outer side of the wrapping layer, and a magnetic composite sheath wrapping the outer side of the coating layer. And the magnetostrictive composite sheath is prepared by compounding Terfenol-D / Metglas and novolac epoxy resin. The optical fiber detection sensing system comprises a laser light source, an acousto-optic modulator, an erbium-doped optical fiber amplifier, a beam splitter, a circulator, a magnetic composite sheath optical fiber sensor, a reference optical fiber sensor, a beam combiner, a detector and a data processor. The optical fiber mine magnetic detection sensor and system are widely applied to underground mineral magnetic field detection, and have the advantages of high sensitivity, high environmental adaptability, low cost and the like.

This invention discloses a multi-channel programmable miniaturized high-speed FBG demodulation system and method based on an AWG (Optical Fiber Optic Generator), belonging to the field of fiber optic sensing technology. The AWG-based multi-channel programmable miniaturized high-speed FBG demodulation system includes a high-stability broadband light source module, a low-loss isolation module, a miniaturized programmable fiber optic amplifier, a circulator, a two-stage miniaturized high-speed optical switch, a high-crosstalk AWG module, a photoelectric conversion module, a programmable A / D conversion module, and a core control module. The AWG-based multi-channel programmable miniaturized high-speed FBG demodulation method involves the optical signal entering an FBG sensor array, the FBG sensor reflecting the optical signal, the reflected optical signal entering the AWG module, and the output light undergoing photoelectric conversion to calculate the center wavelength of the FBG sensor. This invention, based on an AWG, improves demodulation accuracy while ensuring the demodulation range, achieving continuous wavelength demodulation within the AWG wavelength range.

According to the automatic testing system for the optical fiber amplifier for the inter-satellite laser communication terminal, full-automatic execution of the testing process is achieved through the automatic control and intelligent testing technology. The problems that in the prior art, an optical fiber amplifier manual testing technology needs to manually send a control instruction, set instrument parameters, read instrument data and write in a data recording table, and manual guarding is needed during long-time testing are solved. And the technical problems of easy misoperation, complicated operation steps, long test time consumption and high manpower / time consumption cost of manual instruction sending are solved.

A reflection-type leveling optical fiber sensor belongs to the technical field of optical fiber sensors and comprises an optical fiber head, an optical fiber lead, an optical fiber amplifier, an annular flange plate, a leveling assembly and a clamping assembly. The leveling assembly and the optical fiber amplifier are arranged above the annular flange plate in parallel; the clamping assembly is arranged above the leveling assembly; the optical fiber head is arranged on the clamping assembly and connected with the optical fiber amplifier through an optical fiber wire. The optical fiber leveling device has a leveling function, light emitted by the optical fiber head can accurately and vertically irradiate downwards through leveling operation, light reflected from the surface of a detected object can be accurately received, and the detection precision is improved; according to the utility model, the dismounting structure and the adjusting structure of the optical fiber head are simplified, the mounting and dismounting convenience of the optical fiber head is improved, the mounting and debugging difficulty of the optical fiber head is reduced, the long-term stability of the optical fiber sensor is improved, and the applicability of the optical fiber sensor to occasions with narrow space or strict weight requirements is improved; and meanwhile, the production cost is reduced.

This invention discloses a high-speed sweeping fiber optic light source. The specific device includes: a mode-locked pulse light source, an optical fiber amplifier, a highly nonlinear optical fiber, and a dispersion-compensating optical fiber. The passively mode-locked pulse light source outputs a high repetition rate, wide-spectrum mode-locked pulse. Its dispersion propagation follows a parabolic differential equation similar to one-dimensional paraxial diffraction, analogous to Fraunhofer diffraction. The pulse is amplified outside the cavity by an optical fiber amplifier to increase the laser pulse energy and peak power. Then, it is broadened by the highly nonlinear optical fiber to obtain a supercontinuum light source. Finally, the pulse is stretched by a highly dispersive medium provided by the dispersive optical fiber, and the pulse frequency domain spectrum is mapped to a time domain waveform, thereby realizing a high-speed sweeping frequency light source in the time domain.

The invention relates to a method for estimating the ion doping concentration of a rare earth doped optical fiber, and belongs to the technical field of optical fiber amplifiers. An optical fiber to be measured is used for building an optical fiber amplifier, measurement is carried out under the condition of no signal light input, and signal light interference is avoided; reverse fitting is carried out through a simulation model, and the doping concentration is adjusted until the relative error lt is reached; 2%; taking the rare earth ion doping concentration determined in simulation as the doping concentration of the optical fiber to be measured; by measuring the change of the output spectrum of the optical fiber amplifier and comparing the change with a simulation result, the doping concentration is estimated, and the measurement period and the measurement cost are greatly reduced. The method realizes non-destructive and rapid estimation of the doping concentration, remarkably shortens the detection time through real-time measurement and simulation iteration of the spectral power ratio, is low in cost and short in test period, and can be applied to the field of optical fiber amplifier research and other application scenes.

The utility model relates to the technical field of optical fiber communication and laser, in particular to a double-shaft double-wavelength polarization-maintaining ultrahigh-power optical fiber amplifier, which comprises a polarization-maintaining beam splitter, a polarization-maintaining wavelength division multiplexer, a polarization-maintaining doped fiber, a polarization-maintaining beam combiner, a double-cladding polarization-maintaining optical fiber and a polarization-maintaining coupler, the other side of the polarization-maintaining wavelength division multiplexer is in optical fiber connection with a polarization-maintaining doped fiber, the other side of the polarization-maintaining doped fiber is connected with a polarization-maintaining beam combiner, the other side of the polarization-maintaining beam combiner is connected with a double-cladding polarization-maintaining optical fiber, and the other side of the double-cladding polarization-maintaining optical fiber is in optical fiber connection with a polarization-maintaining coupler; according to the utility model, stable and high-power output can be realized on two different spectral wavelengths at the same time, the polarization state of signal light is kept unchanged, the signal quality and the system performance in an optical communication system and industrial laser application are remarkably improved, the dual-wavelength high-power output and the polarization maintaining performance are realized, and the application range is wide. And the reliability and efficiency of the system are improved.

The embodiment of the invention provides an optical transmission amplification method, an optical amplifier, a computer program product and a storage medium. A new working mode is designed in the erbium-doped optical fiber amplifier, and the erbium-doped optical fiber amplifier can enter the working mode when a line fault is monitored. In the working mode, an input optical signal can be blocked on a transmission link in the erbium-doped optical fiber amplifier, so that an output unit which is not influenced by the input optical signal can be isolated in the erbium-doped optical fiber amplifier; on the basis, the output unit can be controlled to generate an output optical signal according to the expected output power during the fault period. Therefore, under the condition that a line fault occurs in an optical transmission system, the erbium-doped optical fiber amplifier can realize decoupling between the output power and the input optical signal based on the working mode, and the output power is not influenced by the input optical signal any more, so that the erbium-doped optical fiber amplifier can still maintain stable output power; therefore, the performance stability of the optical transmission system is ensured.

The invention relates to a multi-stage intelligent control method for driving an optical fiber amplifier, belongs to the technical field of optical fiber amplifiers, solves the problem of insufficient output power control precision of an optical fiber amplifier in the prior art, and comprises the following steps: S1, building a pumping source system, building an optical fiber amplifier system with multi-stage pumping sources, and setting the multi-stage pumping sources, the input seed light and an input signal of the multi-stage pumping source are amplified through multi-stage optical fibers to obtain output power; s2, building a mathematical model of a pumping source system, including building a mathematical model of pumping power of a pumping source and a mathematical model of system output power, and setting initialized input parameters; s3, based on the constructed mathematical model of the pumping source system, executing a control algorithm iteration process to obtain the optimal driving current and the maximum power of the pumping source; and S4, outputting the optimal driving current and the maximum power of the pumping source to the pumping source system, and executing multi-stage intelligent control on the pumping source system.

The application discloses a kind of optical fiber amplifiers without transmission optical fiber and its laser, including the pre-processing module, first module and second module sequentially arranged along the signal light transmission direction;Pre-processing module is connected with first module by first gain optical fiber, first module is connected with second module by second gain optical fiber, to constitute a light amplification mechanism;Different from prior art, the application only uses gain optical fiber in signal light transmission path.Compared with the configuration of transmission optical fiber, the use of gain optical fiber not only can significantly reduce the risk of nonlinear effect, but also avoids the trouble of increasing fusion point caused by introducing transmission optical fiber.In addition, the application also introduces reverse pumping technology, compared with forward pumping, this technology can further weaken nonlinear effect and improve its threshold.

The invention provides a gradient scattering enhanced optical fiber and a design method thereof. The gradient scattering enhanced optical fiber comprises a first enhanced optical fiber, a second enhanced optical fiber and a third enhanced optical fiber, detection pulse signals sent by the plurality of lasers enter the first enhanced optical fiber through the first WDM device; a detection pulse signal transmitted by the first enhanced optical fiber and a first type of amplification signal sent by the first optical fiber amplifier enter a second enhanced optical fiber through a second WDM (Wavelength Division Multiplexer); a detection pulse signal transmitted by the second enhanced optical fiber and a second type of amplification signal sent by the second optical fiber amplifier enter a third enhanced optical fiber through a third WDM (Wavelength Division Multiplexer); the gradient scattering enhanced optical fiber comprises a plurality of optical fiber units, and target scattering rates of different optical fiber units are different or the same; the optical fiber unit determines a signal reflection power based on a reception power of the probe pulse signal and a target scattering rate of the optical fiber unit, and transmits the scattered light signal based on the signal reflection power. According to the scheme, the detection distance of distributed sound wave detection can be remarkably increased.

The invention discloses an optical fiber amplifier without a transmission optical fiber and a laser thereof. The optical fiber amplifier comprises a preprocessing module, a first module and a second module which are sequentially arranged in the signal light transmission direction. The preprocessing module is connected with the first module through a first gain optical fiber, and the first module is connected with the second module through a second gain optical fiber to form a light amplification mechanism; different from the prior art, only the gain optical fiber is adopted in a signal light transmission path. Compared with the configuration of the transmission optical fiber, the use of the gain optical fiber not only can significantly reduce the risk of causing a nonlinear effect, but also avoids the trouble of welding point increase caused by introduction of the transmission optical fiber. In addition, a reverse pumping technology is further introduced, and compared with a forward pumping technology, the technology can further weaken the nonlinear effect and improve the threshold value of the nonlinear effect.