153 results about "Optical fibre amplifiers" patented technology

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 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.

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.

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 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 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.

The invention discloses a multi-parameter distributed optical fiber sensing system and method, and relates to the technical field of optical fiber sensing, the system comprises a laser, a coupler, a modulator, an optical fiber amplifier, an optical fiber circulator, a wavelength division multiplexer, a polarization controller, a mixer, a data acquisition card and a microprocessor; the method comprises the steps that output light of a laser is divided into two paths, a Rayleigh detection pulse coding sequence is generated through a modulator and amplified by an optical fiber amplifier and injected into an optical fiber to be detected, Rayleigh scattering light and Raman scattering light of pulses are separated by a wavelength division multiplexer, the Rayleigh scattering light and adjusted local oscillation light are mixed and then received by a balanced photoelectric detector, and the optical fiber to be detected is obtained. And the data acquisition card carries out subsequent signal processing. According to the invention, a pulse sequence is adopted as a detection light signal to realize receiving demodulation of a Raman scattering signal and a Rayleigh scattering signal, a Gray coded pulse sequence is adopted to realize improvement of a signal-to-noise ratio of the Raman scattering signal and detection of a wide-spectrum signal of the Rayleigh scattering signal, and the detection performance of a vibration signal is improved.

The application discloses a parallel optical fiber amplifier channel equalization system based on signal power adaptive grading, and is characterized in that: the system further comprises a power detection and grading module arranged in front of the parallel amplifier and used for detecting the input optical signal in real time and dividing the optical signal into several power grades based on a preset or adaptive threshold, and a signal distribution and merging module used for guiding the optical signals of different power grades divided to corresponding parallel amplifier paths and merging the optical signals output by each path after the parallel amplifier completes amplification processing to realize channel power equalization; through power grading and differential amplification, the application reduces the difference value of the output power of each channel, realizes intelligent equalization of multi-channel optical signals, improves system gain flatness, effectively reduces the bit error rate caused by power imbalance, avoids the problems of gain saturation of high-power signals and insufficient gain of low-power signals, and improves channel capacity.

An optical fiber amplifier includes a first optical combining / splitting module, a multi-core gain module, and a second optical combining / splitting module. The first optical combining / splitting module is configured to couple a first optical signal to a first gain fiber core. The first gain fiber core is configured to amplify optical power of the first optical signal to obtain a second optical signal, and is configured to couple the second optical signal to the second optical combining / splitting module. The second optical combining / splitting module is configured to couple the second optical signal to a second gain fiber core. The second gain fiber core is configured to amplify optical power of the second optical signal to obtain an amplified second optical signal, where the first gain fiber core and the second gain fiber core separately perform optical power amplification based on different pump optical signals.

The utility model relates to the technical field of optical fiber amplifiers, and discloses a positioning tool for an optical fiber amplifier, which comprises an assembly table, a positioning plate is arranged at the top of the assembly table, a fixing groove is formed in the positioning plate, a shell is placed in the fixing groove, a transmission plate is movably mounted in the fixing groove, and the transmission plate is movably mounted in the fixing groove. And a transmission bin is formed in the rear side of the positioning plate. When the device is pushed by the shell, the transmission plate, the ratchet strip and the pressing plate synchronously displace, when the pressing plate displaces, teeth in the transmission frame drive the gear to rotate, the gear rotates to pull the moving block to displace through the two sets of connecting rods, the shell is clamped by the clamping blocks, and compared with a traditional device, the device can achieve positioning and clamping by pushing the shell, and the clamping efficiency is improved. The dismounting of the shell is completed by rotating the knob, so that the positioning precision is ensured while the dismounting efficiency of the shell is improved, and the workload of workers is reduced.

This invention discloses a transmitting device and its packaging method for improving the performance of a C+L400G fiber amplifier, belonging to the field of optical communication and fiber amplification technology. The device includes an airtight housing, a five-channel pump laser emitting unit, a multiplexing and output unit, a bandwidth gain monitoring unit, a temperature detection unit, and a control and storage unit. The device uses four narrowband monitoring channels to constrain and sample the key gain states of the C-low / C-high / L-low / L-high subbands, and simultaneously collects temperature and the workload of the five pumps. Individualized calibration, threshold determination, and model / parameter writing are completed at the factory stage. During operation, using the monitored signals and temperature as input, a 12-subband gain prediction vector is output through the written prediction model, and the five pump currents are adaptively adjusted using closed-loop control. The packaging method includes steps such as device assembly and connection, sealing and leak detection, factory calibration modeling and writing, and online closed-loop control operation.

A diaphragm-type optical fiber micro-vibration measurement apparatus and method based on a single-pass band microwave photonic filter. The apparatus comprises a broadband light source module (1), a three-port circulator (2), an AU diaphragm optical fiber micro-vibration sensor (3), an erbium-doped optical fiber amplifier (4), a polarization controller (5), an electro-optical modulator (6), a power supply module (7), a radio-frequency source module (8), a dispersion compensation optical fiber (9), a photoelectric detector (10), a data acquisition card (11) and a computer (12), wherein the broadband light source module (1) is connected to one port of the three-port circulator (2) by means of an optical fiber connection line.

A laser system includes a first laser outputting first laser light, an optical intensity changer outputting first pulse laser light, a modulator widening spectral linewidth of the first laser light or the first pulse laser light, an optical fiber amplifier amplifying the first pulse laser light and outputting second pulse laser light, a second laser outputting second laser light, an optical parametric amplifier amplifying the second laser light and outputting third pulse laser light, a wavelength converter outputting fourth pulse laser light using the second and third pulse laser light, an amplification section amplifying the fourth pulse laser light and outputting fifth pulse laser light, and a processor controlling a modulation signal such that the fifth pulse laser light having target spectral linewidth is generated, and controlling the center wavelength of the second laser light such that the fifth pulse laser light having a target center wavelength is generated.

The application discloses a kind of based on microwave field and light field demodulation's fiber grating distributed measurement device and method, measurement device includes broadband light source, polarizer, polarization controller, electro-optic modulator, vector network analyzer, first radio frequency amplifier, 1:99 beam splitter, bias control board, first erbium-doped fiber amplifier, optical circulator, 1x2 optical fiber coupler, transmission optical fiber, FBG array sensing optical fiber, photodetector, second radio frequency amplifier, computer, second erbium-doped fiber amplifier, fiber grating demodulator.The application can realize the spatial continuous distributed measurement of temperature / strain / pressure and the like parameters of fiber along line and high spatial resolution point distribution measurement.

The invention relates to the technical field of optical communication, and provides a gain fluctuation optimization method and device for an erbium-doped optical fiber amplifier. According to the method, the demand slope is kept unchanged, and a relation curve between the fiber length corresponding to the original spectral shape and the attenuation variation is determined; and keeping the demand slope unchanged, and performing addition and subtraction operation to enable the relation curve to be approximate to a regression straight line, thereby obtaining a target spectral shape. According to the invention, the spectral shape is changed only by adding and subtracting the fibers, the gain flattening filter does not need to be replaced, the practicability is high, and the problem that the practicability is poor due to the fact that the gain fluctuation performance index is met by repairing and replacing a large number of gain flattening filters in the prior art is solved.

The utility model discloses a C-band pulse optical fiber amplifier which comprises an optical fiber amplification bin. A sealing mechanism is arranged at the upper end of the optical fiber amplification bin and comprises a sealing plate, L-shaped plates, sliding columns and sliding grooves, the sliding grooves are symmetrically formed in the left end and the right end of the optical fiber amplification bin, the sliding columns are slidably connected into the sliding grooves, the ends, close to the center of the optical fiber amplification bin, of the sliding columns are fixedly connected with the L-shaped plates, and the sliding grooves are formed in the upper end of the optical fiber amplification bin. The C-band pulse optical fiber amplifier further comprises rotary knobs, the rotary knobs are fixedly connected to the ends, away from the center of the optical fiber amplification bin, of the sliding columns, and the width of the L-shaped plates is larger than that of the sliding grooves. Rapid opening and closing of the closing plate can be achieved, and equipment maintenance is facilitated while the sealing performance of the optical fiber amplifier is guaranteed.

The application provides a high-extinction-ratio optical fiber amplifier, which is composed of a first gain optical fiber, an optical blocker and a second gain optical fiber arranged in sequence along an optical path direction, and a pump source is connected to the second gain optical fiber through a beam combiner, wherein the optical path direction of the pump source is opposite to the signal light direction of the optical fiber amplifier; the optical blocker is composed of a double-fiber collimator, a roof prism, a first combination prism, a rotator and a second combination prism arranged in sequence with intervals, and a signal light filter is further arranged in the optical blocker; and the double-fiber collimator is connected with the first gain optical fiber and the second gain optical fiber respectively. The application has a reasonable structure design, filters out the amplified spontaneous emission light generated in the amplification process, reduces the index requirement and cost of the filter through the signal light filter twice, uses the residual pump light in the second amplification as the pump light in the first amplification, realizes the reverse optical isolation protection between the two-stage amplifiers, and improves the extinction ratio of the amplifier as a whole.

The invention discloses a pumping ring structure-based active optical fiber with high pumping conversion efficiency and an amplifier structure, and relates to the field of active optical fibers and optical fiber amplifiers, the pumping ring structure-based active optical fiber comprises a layered structure which is sequentially arranged from inside to outside, and the layered structure comprises a fiber core, a pumping ring structure, a quartz cladding and a coating layer, the optical fiber is located at the geometric center of the active fiber; the pumping ring structure is arranged around the fiber core and is used for guiding and converging pumping light to gather towards a fiber core area, the pumping ring structure is composed of one or more layers of concentric annular modulation areas, and the refractive indexes of all the layers of modulation areas are gradually increased layer by layer from outside to inside in the radial direction; according to the active optical fiber and amplifier structure, one or more layers of concentric pumping rings with refractive indexes gradually increased layer by layer from outside to inside are arranged in the cladding, and the concentration degree and energy density of pumping light towards a fiber core area can be remarkably improved to a certain extent by utilizing the guiding effect of refractive index gradients on a pumping light propagation path; therefore, higher pumping absorption efficiency and gain performance are realized.

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

The application discloses a high-brightness kilowatt 980nm waveband optical fiber laser, and aims at solving the contradiction between power and beam quality improvement of the prior art.The application is composed of U optical fiber laser unit modules, an optical fiber signal beam combiner, an output cladding light filter and an output coupling end.The optical fiber laser unit modules, the optical fiber signal beam combiner, the output cladding light filter and the output coupling end are connected in series.The optical fiber laser unit module is composed of a single-mode seed source and a K-stage optical fiber amplifier, and the single-mode seed source adopts a fiber oscillator.The K-stage optical fiber amplifier is composed of K single-stage optical fiber amplifiers.The optical fiber signal beam combiner performs power beam combination on the laser output by the optical fiber laser unit module, the output cladding light filter filters cladding light, and the output coupling end couples the laser.The application can make the laser have kilowatt power output, and realize beam quality optimization and brightness improvement.

The utility model discloses a kind of control circuit of high-power optical fiber amplifier, it is related to optical fiber amplifier technical field, high-power optical fiber amplifier includes the first stage gain unit and second stage gain unit sequentially arranged along the transmission direction of light;Control circuit includes the control module, first gain control ring and second gain control ring connected;When starting optical fiber amplifier, control module controls first gain control ring to start first stage gain unit, and the output light power of first stage gain unit is collected, control module controls second gain control ring to start second stage gain unit when the output light power of first stage gain unit is greater than threshold light power;When closing optical fiber amplifier, control module first controls second gain control ring to close second stage gain unit, then controls first gain control ring to close first stage gain unit.The control circuit can improve the security and reliability of the high-power optical fiber amplifier application.

The embodiments of the present application provide an optical fiber, an optical fiber manufacturing method, and an optical fiber amplifier, in which the ratios of erbium, aluminum, and phosphorus are adjusted during optical fiber manufacturing, so that aluminum phosphate is formed around the erbium in the manufactured optical fiber, reducing the probability of the erbium in the optical fiber transitioning to a higher energy level and suppressing the excited state absorption effect of the erbium in the optical fiber on an optical signal.

The application discloses a kind of optical fiber and its regulation method with wide bandwidth and high gain in O+E band, including core and cladding (0), core includes first loose layer (1) from outside to inside, first core layer (2), second loose layer (3), second core layer (4) and inner core (5), first loose layer (1), second loose layer (3) are made of quartz material doped with high refractive index GeO2 and P2O5, first core layer (2) and second core layer (4) are doped with Al2O3, bismuth oxide and PbO in order;The gain performance of optical fiber is regulated by regulating the doping molar ratio of Al2O3, bismuth oxide and PbO.The common-doped quartz optical fiber has a gain greater than 15dB in the wavelength range of 1260-1460nm, especially at 1420nm, the gain can reach more than 20dB.The optical fiber structure is simple, the doping concentration is uniform and controllable, and can be widely used in active optical fiber amplifier, high-order vortex light amplifier, fiber laser, fiber sensor and other fields.

The utility model discloses a DAS system based on multi-band linear sweep frequency pulses, 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. According to the system, 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 microwave modulation signals, the frequency interval is determined by the fundamental frequency of the microwave modulation signals, and the continuous light frequency can be flexibly modulated by adjusting the microwave modulation signals, 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 provides a chaotic optoelectronic oscillator time delay characteristic suppression method based on the synergistic effect of a dispersion effect and a wide-spectrum light source. The laser source generates high-stability continuous optical signals, and the polarization state of the continuous optical signals is adjusted through the polarization controller so as to be matched with a polarization sensitive axis of the Mach-Zehnder modulator. The MZM serves as a nonlinear core device, and intensity modulation is carried out on feedback electric signals through a nonlinear transmission function of the MZM. An optical signal output by the MZM is divided into two paths through a first optical coupler, wherein one path enters a monitoring system and is output as a chaotic signal; and the other path enters a photoelectric feedback loop. In a feedback loop, an optical signal firstly enters an erbium-doped optical fiber amplifier for power compensation so as to offset insertion loss caused by subsequent long-distance optical fibers; and then entering a dispersion link formed by cascading a dispersion compensation optical fiber and a standard single-mode optical fiber. According to the invention, by introducing the dispersion link and utilizing the time delay characteristic related to the frequency, the suppression level is improved by about 22.6 dB, and the confidentiality and randomness of the system are greatly enhanced. The structure is simple and standardized.