CN110572207A - Environment self-adaptive laser sheath auxiliary laser communication device and method based on wavefront phase modulation - Google Patents
Environment self-adaptive laser sheath auxiliary laser communication device and method based on wavefront phase modulation Download PDFInfo
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Abstract
An environment self-adaptive 'laser sheath' auxiliary laser communication device and method based on wavefront phase modulation belong to the technical field of free space laser communication, ultra-short pulse light is filamented in the atmosphere to generate 'laser sheath' auxiliary signal light to pass through turbulence, the device tunes the wavefront phase of the pulse light through a wavefront phase modulator and simultaneously controls a variable multiple beam expander, a zoom lens module and an ultra-short pulse laser to realize 'laser sheath' space distribution tuning so as to achieve the real-time and optimal auxiliary effect on the signal light. The invention performs 'black box' processing on the nonlinear process of laser filamentation and the time-varying link environment, tunes the ultrashort pulse light beam, overcomes the defects that the spatial distribution of a 'laser sheath' is not easy to control and the fluctuation of the auxiliary performance is large, has the advantages of strong anti-turbulence capability and environment self-adaption, can realize long-distance and high-stability auxiliary laser communication, and helps the 'laser sheath' auxiliary optical communication to be rapidly applied to a novel technology.
Description
Technical Field
the invention belongs to the technical field of free space laser communication, and particularly relates to application of ultra-short pulse light nonlinear transmission to free space laser communication. The invention designs an environment self-adaptive laser sheath auxiliary laser communication device and method based on wavefront phase modulation by combining with the excellent phase modulation characteristic of a spatial light modulator, can assist signal light transmission in the fields of satellite-ground laser communication, atmospheric laser communication and the like, simultaneously optimizes system parameters, furthest reduces the influence caused by link environment fluctuation, and is particularly suitable for the application of laser communication under strong turbulence and long distance.
Background
The free space laser wireless communication is a communication technology which takes the atmosphere as a transmission medium and takes the laser as a carrier wave to carry out information transmission in the free space, and has the advantages of wide frequency band, high speed, transparent protocol, no need of frequency spectrum license and the like. However, due to the characteristic of poor high-frequency penetrability, atmospheric environments (such as atmospheric turbulence, cloud and fog) will greatly affect communication, and the existing solutions, such as a Multiple Input Multiple Output (MIMO) system, an adaptive optical system (AO), a relay amplification system and the like, have the problems of complex system and high cost, and do not fundamentally solve the atmospheric problem.
the Laser Filamentation phenomenon is a plasma Laser filament which breaks through the diffraction limit and is generated by the balance of the Kerr effect self-focusing and the plasma defocusing effect when ultra-short Laser is transmitted in the air, the radial dimension of a channel reaches 100-200 mu m, and the Laser filament has extremely high power density which can reach 1014W/cm-2. Thus, gases, aerosols, liquids, and even solids can be broken down. Since the phenomenon of laser filamentation was discovered in 1995, the method is widely applied to remote sensing, atmospheric pollutant monitoring, laser lightning, terahertz radiation source, few-cycle pulse generation and the like. Whereas the concept of "laser filamentation assisted optical communication" was not addressed by Alexandru Hening et al until 2014human (Alexandru Hening, et al. laser Communication and propagation through the atom and Oceans III. Vol.9224(2014): J1-8); the Jean-Pierre Wolf project group (Schimmel G, et al. Optica,5(2018):1338-1341.) experiment in 2018 proved that in a water mist environment, a high power density (opening a 100m water mist channel, approximately up to 10kW/cm power density is required), unlike a carbon dioxide laser-2Continuous light) to heat and evaporate water mist, and then to open a channel, shock waves generated by laser filamentation are enough to enable water drops to be expelled outwards by taking a light beam as a center to form a mm-magnitude channel, the channel can be filled with signal light and used for assisting wireless laser communication under strong turbulence, and the channel is called as a laser sheath. There are many characteristic parameters that describe a filament, for example: filamentation length: due to the limitation of the prior art on the peak power, repetition frequency and pulse width of pulse light, the filamentation distance of kilometer magnitude can be realized internationally at most at present, and nevertheless, the laser filamentation can also be applied to the auxiliary communication of short distance or partial link, and the strong anti-turbulence capability is shown; filamentation position: the laser sheath is controlled to be generated at a strong air turbulence position, so that the limited filamentation distance is utilized to the maximum extent to achieve the maximum auxiliary effect; initial chirp amount of pulse: the method is used for compensating group velocity dispersion in the air propagation process, and the control of the laser filamentation position and length can be realized by the method; spatial distribution of "laser sheath": the parameter will determine the effect of assisting optical communication, and as laser filamentation is a complex nonlinear process influenced by multiple factors of audiences, the atmospheric environment, the space distribution of pulsed light, the parameters of ultra-short laser pulse and the like strongly influence the space distribution of the generated laser sheath. And in practical environment, the environment of the communication link is changed along with time and space, which results in the nonlinear refractive index n of the ultrashort pulse in nonlinear transmission2Fluctuating, thereby causing a series of problems: for example: the length change of the laser sheath, the position change of the laser sheath, the space distribution change of the laser sheath and the like, which seriously affect the effect of assisting laser communication and even negatively affect communication light, are one of the reasons why the technology cannot be rapidly applied. Therefore, a set of self-adaptive laser sheath in atmospheric environment is providedThe auxiliary laser communication device and the auxiliary laser communication method have important significance for realizing laser communication in severe environment. The traditional adaptive optics method is to reconstruct the signal light wave front through an adaptive optical path at a receiving end, while the invention proposes adaptive reconstruction of the spatial distribution of a laser sheath, which is essentially different from the former method, and simultaneously, a reasonable design is proposed.
Since the technology of the wireless communication assisted by laser filamentation is developed later, the application of the technology is limited to the stages of theoretical research and laboratory short-distance communication assistance, and no scheme and report about the environment self-adaptive laser sheath assisted optical communication based on wavefront phase modulation exists at present.
disclosure of Invention
the invention aims to solve the problem that the auxiliary performance is reduced or even fails due to the change of the environment of a communication link when the laser sheath assists laser communication, and provides an environment self-adaptive laser sheath auxiliary optical communication device and method based on wavefront phase modulation and beam shaping methods, wherein the environment self-adaptive laser sheath auxiliary optical communication device and method are used for processing the complex influence of environmental factors on the nonlinear transmission of pulsed light. The method can obtain stable 'laser sheath' auxiliary optical communication effect and greatly improve the auxiliary communication distance.
In order to achieve the purpose, the invention adopts the technical scheme that:
An environment self-adaptive 'laser sheath' auxiliary laser communication device based on wavefront phase modulation is characterized in that: the device comprises a signal light path consisting of a laser communication transmitter, a third convex lens and a fourth convex lens, and an ultrashort pulse light path consisting of an ultrashort pulse laser, a first convex lens, a second convex lens, a diaphragm, a polarizer, a beam splitter and a wavefront phase modulator, wherein the wavefront phase modulator is arranged on a transmission light path of the beam splitter;
The variable-multiple beam expander comprises a variable-multiple beam expander, a dichroic mirror, a zoom lens module, an optical filter and a laser communication receiver, which are sequentially arranged on a reflection light path of a beam splitter; the ultrashort pulse light reflected by the beam splitter enters the dichroic mirror after passing through the variable-multiple beam expander, the signal light path and the ultrashort pulse light path are coaxially combined by the dichroic mirror, after the combined light is focused by the zoom lens module, the ultrashort pulse light generates laser sheath auxiliary signal light at an atmospheric turbulence position to pass through, and only the signal light passes through the optical filter and is received by the laser communication receiver;
The computer is in wireless connection with the ultrashort pulse laser, the wavefront phase modulator, the variable multiple beam expander, the zoom lens module and the laser communication receiver, and sequentially controls the beam expansion multiple of the variable multiple beam expander, the focal length of the zoom lens module, the distance of a compression grating of the ultrashort pulse laser and a kinoform in the wavefront phase modulator according to the received signal power, so that the space distribution optimization of a laser sheath is realized, and the purpose of outputting the highest signal light power in given time is achieved.
Further, the response frequency of the zoom lens module is 1MHz, and the zooming range is 10m to 10 km; the output peak power of the ultrashort pulse laser reaches or exceeds the level of Taiwa, the pulse width is less than 50ps, and the repetition frequency is more than 50 Hz; the wave front phase modulator refreshes a rectangular pixel domain with frequency of 1kHz or more and a 1920 x 1080 phase surface, and the area of the kinoform needing computer optimization is the area outside the 1164 x 655 rectangular domain at the center of the phase surface.
Further, the diameter of the expanded light spot of the ultra-short pulse light by the first convex lens and the second convex lens is equal to or slightly larger than the aperture of the diaphragm.
furthermore, the ratio of the diameter of the light spot of the front pulse light of the zoom lens module to the diameter of the light spot of the signal light is larger than 4.
An environment self-adaptive 'laser sheath' auxiliary laser communication method based on wavefront phase modulation comprises the following steps:
1) And opening the ultrashort pulse laser, and adjusting the first convex lens and the second convex lens to expand the ultrashort pulse light to enable the diameter of a light spot to be equal to or slightly larger than the aperture of the diaphragm so as to match the wavefront phase modulator.
2) Controlling a computer to load a kinoform, enabling the polarization direction of input light to be the same as the liquid crystal direction in the modulator by adjusting the polarizer so as to achieve the optimal modulation effect, and unloading the kinoform after adjustment;
3) adjusting the variable-multiple beam expander to expand the modulated pulse light, adjusting a third convex lens and a fourth convex lens to control the signal light spot so that the combined light between the dichroic mirror and the zoom lens module is coaxial, and the ratio of the diameter of the signal light spot to the diameter of the pulse light spot in front of the zoom lens module is more than 4;
4) Estimating an expected filamentation position according to the environment of a communication link, and realizing that pulsed light generates a laser sheath at the expected position to assist laser communication by adjusting the beam expansion multiple of a variable-multiple beam expander and the equivalent focal length of a zoom lens module;
5) after a communication link is established, a laser communication receiver receives signal light and feeds back the signal power value to a computer, the computer performs sequence control, and in the first step, the beam expansion multiple of a variable multiple beam expander and the equivalent focal length of a zoom lens module are controlled to optimize the position and the length of a laser sheath; secondly, controlling the spacing of a pulse compression grating pair in the femtosecond laser to tune the initial chirp quantity to compensate group velocity dispersion and further optimizing the position, length and spatial distribution of a laser sheath; thirdly, within a given time limit, the computer calculates a kinoform by using a rapid convergence algorithm to perform wavefront phase modulation on the ultrashort pulse light, and further optimization of spatial distribution of a laser sheath is mainly realized; the three steps are an optimization period. If the power of the received signal is reduced by 5% compared with that before optimization at a certain moment, entering the next optimization period, and optimizing the 'laser sheath' parameter in real time to realize the environment self-adaptation function.
The invention has the advantages and beneficial effects that:
An environment self-adaptive 'laser sheath' auxiliary optical communication device and method based on wavefront phase modulation uses a 'laser sheath' generated by nonlinear transmission of ultrashort pulse light for auxiliary optical communication, can greatly reduce laser power required by laser penetrating through atmospheric turbulence, and is a reliable auxiliary optical communication scheme because the intensity of the 'laser sheath' cannot be attenuated within a long distance due to a light intensity clamping effect. In order to solve the problem that the link environment disturbs the spatial distribution of the laser sheath along with the time and spatial changes, the method can realize the tuning of the length and the position of the laser sheath by means of methods of wave front phase modulation and beam shaping, flexibly, efficiently and quickly modulate the wave front phase of pulse light, and realize the reconstruction of the spatial distribution of the laser sheath. Compared with the existing laser sheath assisted optical communication technology with the auxiliary distance of only several meters, the auxiliary distance is increased to the kilometer magnitude, the laser sheath assisted long-distance optical communication provides more possibility, and the laser sheath assisted long-distance optical communication technology is expected to be applied to aspects such as satellite-ground laser communication, a vertical return/forward transmission frame of a 5G wireless network and the like in the future.
drawings
Fig. 1 is an optical path diagram of an environment adaptive "laser sheath" auxiliary optical communication device based on wavefront phase modulation.
in the figure: 1. the laser comprises an ultrashort pulse laser, 2, a first convex lens, 3, a second convex lens, 4, a diaphragm, 5, a polarizer, 6, a beam splitter, 7, a wavefront phase modulator, 8, a variable-multiple beam expander, 9, a laser communication transmitter, 10, a third convex lens, 11, a fourth convex lens, 12, a dichroic mirror, 13, a zoom lens module, 14, an optical filter, 15, a laser communication receiver and 16, and a computer.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings. The invention realizes the reconstruction of the space distribution of the laser sheath by the methods of modulating the wavefront phase of the pulse light and shaping the light beam, and realizes the function of self-adaptive auxiliary laser communication of the laser sheath in a strong turbulent environment. As shown in fig. 1, the environment adaptive "laser sheath" auxiliary optical communication apparatus and method based on wavefront phase modulation proposed by the present invention includes: the device comprises an ultrashort pulse laser 1, a first convex lens 2, a second convex lens 3, a diaphragm 4, a polarizer 5, a beam splitter 6, a wavefront phase modulator 7, a variable-multiple beam expander 8, a laser communication transmitter 9, a third convex lens 10, a fourth convex lens 11, a dichroic mirror 12, a zoom lens module 13, an optical filter 14, a laser communication receiver 15 and a computer 16.
The position relation of each component of the invention is as follows:
The ultra-short pulse optical path comprises a signal optical path consisting of a laser communication transmitter 9, a third convex lens 10 and a fourth convex lens 11, and an ultra-short pulse optical path consisting of an ultra-short pulse laser 1, a first convex lens 2, a second convex lens 3, a diaphragm 4, a polarizer 5, a beam splitter 6 and a wavefront phase modulator 7. Wherein the wavefront phase modulator 7 is arranged on a transmission light path of the beam splitter 6; the variable-magnification beam expander 8, the dichroic mirror 12, the zoom lens module 13, the optical filter 14 and the laser communication receiver 15 are sequentially arranged on a reflection light path of the beam splitter 6. Ultrashort pulsed light reflected by the beam splitter 6 enters the dichroic mirror 12 after passing through the variable multiple beam expander 8, the signal light path and the ultrashort pulsed light path are coaxially combined by the dichroic mirror 12, after the combined light is focused by the zoom lens module 13, the ultrashort pulsed light generates 'laser sheath' auxiliary signal light at an atmospheric turbulence position and passes through, and only the signal light is received by the laser communication receiver 15 through the filter sheet 14 to realize communication. The computer 16 is wirelessly connected with the ultrashort pulse laser 1, the wavefront phase modulator 7, the variable multiple beam expander 8, the zoom lens module 13 and the laser communication receiver 15. The computer 16 sequentially controls the beam expansion multiple 8 of the variable multiple beam expander, the focal length of the zoom lens module 13, the distance of the compression grating pair of the ultrashort pulse laser 1 and the kinoform in the wavefront phase modulator 7 according to the received signal power, so that the space distribution optimization of a laser sheath is realized, and the purpose of outputting the highest signal light power in a given time is achieved.
The environment self-adaptive laser sheath auxiliary optical communication device and method based on wavefront phase modulation, which are formed by the components, are carried out according to the following steps:
The ultrashort pulse laser 1 uses 5TW peak power, 805nm center wavelength, 40fs pulse width, 0.2J single pulse energy, 100Hz repetition frequency and 20W average power. The resolution of the wave front phase modulator 2 is 1920 multiplied by 1080, the refresh frequency is 1kHz, the pixel size is 10 mu m, and the phase surface range is 19.2 multiplied by 10.8mm2laser damage threshold 10W/cm2. The power density of the incident wavefront phase modulator 7 thus calculated is about 9.65W/cm2less than the laser damage threshold and therefore meets the requirements. Step 1, opening the ultrashort pulse laser 1, adjusting the first convex lens 2 and the second convex lens 3 to expand the ultrashort pulse light, and enabling the diameter of a light spot to be equal to or slightly larger than the aperture of the diaphragm 4 so as to match the wavefront phase modulator 7. Step 2, byThe control computer 16 loads the second-order vortex rotation kinoform, and after the ultrashort pulse light enters the wavefront phase modulator 7, the modulated pulse light after phase modulation is reflected, at this time, the modulated pulse light is observed by a near-infrared camera (not shown in fig. 1), and the polarizer 5 is adjusted at the same time, so that the polarization direction of the input light is the same as the liquid crystal direction in the modulator, and the optimal modulation effect is achieved. And after the adjustment is finished, unloading the kinoform and withdrawing the CCD from the optical path. And step 3, the modulated pulse light reflected is expanded by the variable multiple beam expander 8, the laser communication transmitter 9 transmits signal light, the wavelength of the signal light is 1550nm, the transmitting power is 2W, the diameter of a signal light beam spot is controlled by the third convex lens 10 and the fourth convex lens 11, and after the two are combined by the dichroic mirror 12, the obtained pulse light and the signal light beam waist radius are respectively 5cm and 1mm, and the two are coaxial. And 4, in the example, the optical communication link is 2km, and if strong turbulence appears at a position 9200m away from the laser communication transmitter according to the link environment estimation, the target filamentation position is the position. By laser filamentation position Zf' calculation formula:
Where P is the ultrashort laser peak power, 3TW in this example; pcrfor auto-focusing threshold power, P is estimated from the weather conditions in this examplecrAbout 3 GW; wave vector k 2 pi/lambda 7.85 × 106m-1(ii) a a is the beam waist radius of the pulse light beam is 5 cm; zf234.19m can be obtained by calculation for the laser filamentation self-focusing position; an equivalent focal length f of the zoom lens module 13 is designed according to the target focus positioneffIs 1370 m. After the two beams of light are weakly focused by the zoom lens module 13, ultrashort pulsed light is emitted at a target position (from the laser communicationPosition 9200 m) to generate a laser sheath, and the signal light is prevented from being interfered by strong turbulence with the aid of the laser sheath. And 4, filtering out background stray light including ultrashort pulse light by using an optical filter 14 at the receiving end, allowing only signal light to pass through, processing the signal light by using a laser communication receiver 15 to realize optical communication, and feeding power information back to the computer 16. And step 5, the spatial distribution of the laser sheath changes due to the link environment, the auxiliary performance is unstable, and the computer 16 sequentially controls the devices at the transmitting end. Firstly, controlling a variable multiple beam expander 8 to change the beam waist a of a pulse light beam, and realizing the large-range tuning of the position and the length of a laser sheath; then, the zoom lens module 13 is controlled to realize the small-range and high-precision tuning of the position and the length of the laser sheath; on the basis, the pulse compression grating pair spacing in the femtosecond laser 1 is controlled to tune the initial chirp quantity to realize the further optimization of the position, length and spatial distribution of a laser sheath; finally, based on a simulated annealing algorithm, the computer 16 is used for optimizing the region outside the rectangular domain of 1164 × 655 in the central position of the phase plane in the kinoform of the wavefront phase modulator 7, 2-second optimization time is set, multiple iterations are completed within 2 seconds, the kinoform when the power of the highest signal light is output within the time period is used by the computer 16 to complete the pulse light modulation, and a laser sheath generated by the modulated pulse light has better auxiliary signal light performance. The above is an optimization period, and due to the disturbance of turbulence in time and space, if the received signal power is reduced by 5% compared with that before optimization, the next optimization period is entered, so as to realize the function of environment self-adaptive laser sheath assisted optical communication. The invention applies laser filamentation to laser communication, effectively solves the problem of reduced auxiliary performance of the laser sheath caused by link environment fluctuation, and has wide application prospect in the field of wireless laser communication.
The present invention is not limited to the above-described real-time manner, and the above-described embodiments are only illustrative and not restrictive. Those skilled in the art can make various modifications without departing from the spirit of the invention and the scope of the appended claims.
Claims (6)
1. An environment self-adaptive 'laser sheath' auxiliary laser communication device based on wavefront phase modulation is characterized in that: the device comprises a signal light path consisting of a laser communication transmitter (9), a third convex lens (10) and a fourth convex lens (11), and an ultrashort pulse light path consisting of an ultrashort pulse laser (1), a first convex lens (2), a second convex lens (3), a diaphragm (4), a polarizer (5), a beam splitter (6) and a wavefront phase modulator (7), wherein the wavefront phase modulator (7) is arranged on a transmission light path of the beam splitter (6);
The device comprises a variable multiple beam expanding lens (8), a dichroic mirror (12), a zoom lens module (13), an optical filter (14) and a laser communication receiver (15), which are sequentially arranged on a reflection light path of a beam splitting lens (6); ultrashort pulse light reflected by the beam splitter (6) enters the dichroic mirror (12) after passing through the variable-multiple beam expander (8), the signal light path and the ultrashort pulse light path are coaxially combined by the dichroic mirror (12), after the combined light is focused by the zoom lens module (13), the ultrashort pulse light generates laser sheath auxiliary signal light at an atmospheric turbulence position to pass through, and only the signal light passes through the optical filter (14) and is received by the laser communication receiver (15);
The system comprises a computer (16) which is in wireless connection with an ultrashort pulse laser (1), a wavefront phase modulator (7), a variable multiple beam expander (8), a zoom lens module (13) and a laser communication receiver (15), wherein the computer (16) sequentially controls the beam expansion multiple of the variable multiple beam expander (8), the focal length of the zoom lens module (13), the distance between compression gratings of the ultrashort pulse laser (1) and a kinoform diagram in the wavefront phase modulator (7) according to received signal power, so that the optimization of the spatial distribution of a laser sheath is realized, and the purpose of outputting the highest signal light power in given time is achieved.
2. The wavefront phase modulation based environmentally adaptive "sheath" assist laser communication device of claim 1, wherein: the response frequency of the zoom lens module (13) is 1MHz, and the zooming range is 10m to 10 km; the output peak power of the ultrashort pulse laser (1) reaches a level of terawatt or above, the pulse width is less than 50ps, and the repetition frequency is greater than 50 Hz; the wavefront phase modulator (7) refreshes a rectangular pixel domain with a frequency of 1kHz or more and a phase plane of 1920 x 1080, and wherein the region where the computer (16) is required to optimize the kinoform is a region outside the rectangular domain of 1164 x 655 at the center of the phase plane.
3. The wavefront phase modulation based environmentally adaptive "sheath" assist laser communication device of claim 1, wherein: the diameters of light spots expanded by the first convex lens (2) and the second convex lens (3) to the ultrashort pulse light are equal to or slightly larger than the aperture of the diaphragm (4).
4. The wavefront phase modulation based environmentally adaptive "sheath" assist laser communication device of claim 1, wherein: the ratio of the front pulse light spot diameter of the zoom lens module (13) to the signal light spot diameter is larger than 4.
5. An environment adaptive 'laser sheath' auxiliary laser communication method based on wavefront phase modulation, which is realized by the device of any one of claims 1-4, and is characterized by comprising the following steps:
1) Opening the ultrashort pulse laser (1), adjusting the first convex lens (2) and the second convex lens (3) to expand the ultrashort pulse light to enable the diameter of a light spot to be equal to or slightly larger than the aperture of the diaphragm (4) so as to match the wavefront phase modulator (7);
2) loading a kinoform by a control computer (16), enabling the polarization direction of input light to be the same as the direction of liquid crystal in the modulator by adjusting a polarizer (5) so as to achieve the optimal modulation effect, and unloading the kinoform after adjustment;
3) Adjusting a variable-multiple beam expander (8) to expand the modulated pulse light, adjusting a third convex lens (10) and a fourth convex lens (11) to control the signal light spot, so that the combined light between a dichroic mirror (12) and a zoom lens module (13) is coaxial, and the ratio of the diameter of the front pulse light spot of the zoom lens module (13) to the diameter of the signal light spot is greater than 4;
4) the expected filamentation position is estimated according to the environment of a communication link, and the pulsed light is generated to assist laser communication at the expected position by adjusting the beam expansion multiple of the variable-multiple beam expander (8) and the equivalent focal length of the zoom lens module (13);
5) After a communication link is established, the laser communication receiver (15) receives the signal light and feeds back the signal power value to the computer (16), thereby realizing environment self-adaptive 'laser sheath' auxiliary laser communication.
6. The method of claim 5, wherein the method comprises: in step 5), the computer (16) performs the following sequence control,
Firstly, controlling the beam expansion multiple of a variable-multiple beam expander (8) and the equivalent focal length of a zoom lens module (13) to optimize the position and the length of a laser sheath;
Secondly, controlling the spacing of a pulse compression grating pair in the femtosecond laser (1) to tune the initial chirp quantity to compensate group velocity dispersion and further optimize the position, length and spatial distribution of a laser sheath;
Thirdly, within a given time limit, the computer (16) uses a fast convergence algorithm to calculate a kinoform to carry out wavefront phase modulation on the ultrashort pulse light, and further optimization of the spatial distribution of the laser sheath is mainly realized;
The three steps are an optimization period, if the power of the received signal is reduced by 5% compared with that before optimization at a certain moment, the next optimization period is entered, and the laser sheath parameter is optimized in real time to realize the environment self-adaptive function.
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