Variable distance anti-turbulence double-defocusing regulation bessel-like optical communication method and device

Abstract

Variable distance anti-turbulence double defocus regulation Bessel-like light communication method and device belong to optical communication technical field, in order to solve the existing problems, the device includes: laser light source, electro-optic modulator, fiber amplifier and fiber tail fiber through optical fiber connection in turn;The output port of fiber tail fiber is located on the focal plane of collimating mirror;Collimating mirror, axicon mirror one, axicon mirror two and eyepiece coaxial arrangement;The back surface of the cone angle of axicon mirror one is perpendicular to the optical axis of collimating mirror, and axicon mirror two is arranged in axial symmetry with axicon mirror one;The light emitted from the eyepiece is incident to the folding mirror one, the light reflected by the folding mirror one is incident to the folding mirror two, the light reflected by the folding mirror two is incident to the newton objective, and the light is finally emitted parallelly by the newton objective;The optical axis of the light emitted by the newton objective is parallel to the optical axis of the light emitted by the collimating mirror;The present application realizes atmospheric parameter measurement and signal stable transmission in free space optical communication.

Description

Technical Field

[0001] This invention belongs to the field of optical communication technology, specifically relating to a variable-distance, turbulence-resistant, dual-defocus control Bessel-like optical communication method and device. Background Technology

[0002] High-speed laser communication is a crucial component of integrated space-ground communication, and space-to-ground and ground-to-ground links are vital in modern communications. With the continuous development of networks such as 5G and 6G, the transmission density and speed requirements of communication systems are increasing. Due to the presence of atmospheric channels, laser communication faces numerous challenges during long-distance propagation, including signal attenuation, beam scattering, and intensity fluctuations caused by turbulence. These problems lead to a decline in the performance of existing laser communication systems, particularly in complex weather and atmospheric environments.

[0003] To address these issues, existing solutions primarily rely on increasing the emission power of the laser source, improving the beam transmission system, and enhancing the beam's adaptability to atmospheric interference. Among these, employing special beam shapes (such as ring beams) or diffraction-free beams is an important technological direction with significant application prospects in fields such as laser communication, radar, ranging, and target tracking.

[0004] Chinese Patent Publication No. CN120710592A, entitled "A Diffraction-Free Laser Communication Terminal Based on Bessel Beams," describes a device comprising a beacon transmitting laser, a beacon transmitting module consisting of a first collimating beam expander, a first axial pyramid, and a first collimating lens; an optical antenna module consisting of a primary mirror and a secondary mirror; a beacon receiving module consisting of a first narrowband filter, a first focusing mirror, and a CMOS detector; a beacon transmitting module consisting of a signal transmitting laser, a second collimating beam expander, a second axial pyramid, and a second collimating lens; a signal receiving module consisting of a second narrowband filter, a second focusing mirror, and an APD detector; and a beam splitting module consisting of a fast reflector, a quarter-wave plate, a dichroic mirror, and a polarizing beam splitter.

[0005] The device still has certain limitations in terms of structure and beam control capability, namely, difficulties in the generation and transmission control of Bessel beams. Specifically, it is difficult to control the distribution of beam superposition area according to different distances and atmospheric conditions, resulting in insufficient link margin under variable distance or strong turbulence conditions, and the inability to control the energy of inner and outer loops, leading to low received energy density. Summary of the Invention

[0006] To address the challenge of dynamically controlling the distribution of the superposition region of the beam in existing free-space optical communication systems based on special anti-interference beams under varying distances and atmospheric conditions, this invention proposes a variable-distance, turbulence-resistant, dual-defocus control quasi-Bessel optical communication method and device. This method leverages the stable transverse optical field distribution and good self-healing properties of quasi-diffraction-free Bessel beams to improve the free-space optical communication link's ability to suppress intensity fluctuations and flicker caused by turbulence, thereby achieving stable signal transmission in atmospheric parameter measurement and free-space optical communication.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A variable-distance, turbulence-resistant, dual-defocus control type Bessel optical communication device, comprising: a laser source, an electro-optic modulator, an optical fiber amplifier, an optical fiber pigtail, a z-axis adjustment stage one, a collimating lens, an axial cone lens one, an axial cone lens two, an eyepiece, a z-axis adjustment stage two, a folding mirror one, a folding mirror two, and a Newton objective lens.

[0009] The laser source, electro-optic modulator, fiber amplifier, and fiber optic pigtail are sequentially connected via optical fibers; the output port of the fiber optic pigtail is located on the focal plane of the collimating lens; the collimating lens, axial conical lens one, and axial conical lens two are coaxially arranged with the eyepiece; the back face of the cone angle of axial conical lens one is perpendicular to the optical axis of the collimating lens, and axial conical lens two is symmetrically arranged with axial conical lens one; the light emitted from the eyepiece is incident on folding mirror one, the light reflected by folding mirror one is incident on folding mirror two, the light reflected by folding mirror two is incident on Newton's objective lens, and the light finally exits parallel through Newton's objective lens; the optical axis of the light emitted through Newton's objective lens is parallel to the optical axis of the light emitted through the collimating lens;

[0010] The continuous laser output from the laser source is transmitted to an electro-optic modulator via optical fiber. The electro-optic modulator modulates the amplitude or phase of the laser according to an external control signal to generate a modulated laser signal that meets communication requirements. The modulated laser signal is injected into an optical fiber amplifier through an optical fiber. After being amplified by the optical fiber amplifier, it is output to an optical fiber pigtail through the transmission optical fiber. After the defocusing state of the beam is adjusted by the z-axis adjustment stage, the light is transmitted to a collimating lens. The collimating lens collimates the input beam into a parallel beam and outputs it to an axial conical lens. After being refracted by the axial conical lens, a conical beam is formed. This conical beam is incident on an axial conical lens. By adjusting the distance between the two axial conical lenses, a Bessel-like beam with no diffraction characteristics is generated.

[0011] The Bessel-like beam is magnified by the eyepiece to match the beam aperture, and then incident on the Newton objective lens through folding mirror one and folding mirror two. Finally, the Bessel-like beam is expanded and collimated by the eyepiece, z-axis adjustment stage two, folding mirror one, folding mirror two and Newton objective lens to form a long-distance transmission beam that is projected to a long-distance communication target.

[0012] The z-axis adjustment stage includes a fixed clamping bracket and a movable platform that can slide along the z-axis. The fixed clamping bracket is mounted on the movable platform. The output end of the optical fiber pigtail is fixedly clamped to the fixed clamping bracket. By rotating the knob of the movable platform, the output port of the optical fiber pigtail can be moved back and forth along the z-axis, thereby achieving defocus control.

[0013] The z-axis adjustment stage 2 includes a fixed clamping bracket 2 and a movable platform 2 that can slide along the z-axis. The fixed clamping bracket 2 is mounted on the movable platform 2. The outer lens barrel of the eyepiece is fixedly embedded in the fixed clamping bracket 2 to ensure that the optical axis of the eyepiece is strictly coaxial with the main optical axis of the system. By rotating the knob of the movable platform 2, the eyepiece can be moved back and forth along the z-axis, thereby achieving defocus control.

[0014] A communication method for a Bessel-like optical communication device based on variable-distance anti-turbulence dual-defocus control, the method comprising the following steps:

[0015] Step 1: Modeling: Using the optical design software Zemax, an optical system model of a variable-distance, anti-turbulence, dual-defocus control Bessel-like optical communication device is established. By simulating the individual and hybrid adjustment of the fiber optic pigtail defocus and eyepiece defocus, different beam convergence distances and beam superposition region parameters are obtained, and beam output performance is analyzed. Thus, a dataset of different distances and beam superposition region parameters and corresponding fiber optic pigtail and eyepiece defocus adjustment amounts is constructed.

[0016] Step 2, Communication: Based on the required communication distance and coverage area in the actual communication process, extract the fiber optic pigtail defocus and eyepiece defocus data corresponding to the required distance and area parameters from the dataset obtained in Step 1. Adjust the Z-axis adjustment stage 1 and Z-axis adjustment stage 2 according to the extracted data to obtain the initial position. Then, initiate laser communication. The laser source outputs continuous laser light, which is modulated by an electro-optic modulator according to an external control signal to generate a communication signal. After being amplified by an optical fiber amplifier, the signal is output from the fiber optic pigtail fixed on Z-axis adjustment stage 1. The emitted beam is collimated by the collimating lens group and then passes sequentially through the opposing axis conical mirrors 1 and 2, generating a Bessel-like beam with no diffraction characteristics. This beam continues to be incident on the eyepiece controlled by Z-axis adjustment stage 2 for aperture adaptation amplification, and then guided by folding mirrors 1 and 2 to the Newton objective lens before being emitted towards the communication target. Simultaneously, communication quality monitoring is activated at the receiving end. Based on the initial values, the applied defocus amount and feedback values ​​from the communication receiving end are iterated to obtain the optimal solution for the defocus amount and antenna parameters, thus completing the parameter implementation at the communication transmitting end.

[0017] Step 3, Adjustment: In response to the time-varying communication channel and the changes in the optical axis of the laser communication device, fine-tune the z-axis adjustment stage one to adjust the beam coverage range at a fixed distance, thereby achieving effective beam coverage; in response to the time-varying communication distance, fine-tune the z-axis adjustment stage two to adjust the defocus state of the beam, thereby achieving beam convergence and alignment under varying distances.

[0018] Step 4, Monitoring: Based on the optical power efficiency, received power, and bit error rate received by the laser communication receiver, make slight adjustments to the z-axis adjustment stage one and z-axis adjustment stage two in the device to obtain the optimal communication reception quality;

[0019] Step 5; Repeat: If there are drastic changes in communication distance and a significant decrease in communication quality, repeat steps 2-4.

[0020] The beneficial effects of this invention are:

[0021] 1) This invention proposes a dual defocusing adjustment method, which mainly designs a fiber optic cable combined with a z-axis adjustment stage to achieve defocusing adjustment of the laser source, and combines it with an eyepiece combined with a z-axis adjustment stage for combined control. This design can achieve precise control over the divergence and centerline convergence point of the Bessel-like beam emitted from the Newton objective lens, making the axial power distribution autonomously controllable during beam transmission. It can provide the optimal transmission power peak for different target distances, thus effectively solving the problem of dynamically adjusting the beam superposition area distribution according to different distances and atmospheric conditions in traditional methods, and meeting the needs of high-performance variable distance and variable area scenarios in long-distance communication.

[0022] 2) This invention proposes a structure in which the cone-shaped surfaces of the first and second axial conical mirrors are opposite each other and perpendicular to the optical axis of the collimating lens group, so as to realize the redistribution of the inner and outer ring energy of the laser light source, improve the outer ring energy ratio of the beam, and form a central light intensity interference superposition region during long-distance transmission. At the same time, it improves the light intensity concentration in the central region over long distances, and the upper limit of the peak power of the central light intensity is higher during long-distance transmission, thereby increasing the received energy density. Combined with the eyepiece, z-axis adjustment stage, folding mirror one, folding mirror two, and Newton's objective lens, long-distance transmission of the light center peak interference beam can be realized. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the variable-distance anti-turbulence dual-defocus control Bessel-like optical communication device of the present invention;

[0024] Figure 2 The pigtail and z-axis adjustment table device described in this invention;

[0025] Figure 3 The eyepiece and z-axis adjustment stage device described in this invention;

[0026] Figure 4Figure (a) shows the beam coverage area diagrams with different adjustment amounts described in this invention; Figure (b) shows the case when the defocus amount is adjusted to the minimum beam coverage area;

[0027] Figure 5 This is a schematic diagram of the experimental test site for atmospheric beam transmission of the 3.6km beam described in this invention.

[0028] Figure 6 This is a time-domain diagram of the Gaussian beam received at 3.6km as described in this invention;

[0029] Figure 7 This is a time-domain diagram of the Bessel-like beam received at 3.6km as described in this invention;

[0030] Figure 8 This is a statistical chart of the received signals of the Gaussian beam and the Bessel-like beam described in this invention over a distance of 3.6 km. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings.

[0032] like Figure 1 As shown, a variable-distance, anti-turbulence, dual-defocus control type Bessel optical communication device includes: a laser source 1, an electro-optic modulator 2, an optical fiber amplifier 3, an optical fiber pigtail 4, a z-axis adjustment stage 1 5, a collimating lens 6, an axial cone lens 1 7, an axial cone lens 2 8, an eyepiece 9, a z-axis adjustment stage 2 10, a folding mirror 1 11, a folding mirror 2 12, and a Newtonian objective lens 13.

[0033] like Figure 2 As shown, the z-axis adjustment stage 5 includes a fixed clamping bracket 5-1 and a movable platform 5-2 that can slide along the z-axis. The fixed clamping bracket 5-1 is mounted on the movable platform 5-2; the output end of the fiber optic pigtail 4 is fixedly clipped onto the fixed clamping bracket 5-1. By rotating the knob on the movable platform 5-2, the output port of the fiber optic pigtail 4 can be moved back and forth along the z-axis (beam transmission direction), thereby achieving defocus control.

[0034] like Figure 3 As shown, the z-axis adjustment stage 2 10 includes a fixed clamping bracket 2 10-1 and a movable platform 2 10-2 that can slide along the z-axis. The fixed clamping bracket 2 10-1 is mounted on the movable platform 2 10-2. The outer lens barrel of the eyepiece 9 is fixedly embedded in the fixed clamping bracket 2 10-1, ensuring that the optical axis of the eyepiece 9 is strictly coaxial with the main optical axis of the system. The eyepiece 9 can be moved back and forth along the z-axis (beam transmission direction) by rotating the knob of the movable platform 2 10-2, thereby achieving defocus control.

[0035] like Figure 4The image shows the simulation results obtained from Zemax software simulations of the range of beam coverage area variation under different defocusing amounts. Figure 4 (a) indicates the case where the defocus is adjusted to the minimum beam coverage area; Figure 4 (b) shows the case when the defocus amount is adjusted to the maximum beam coverage area. Based on this simulation result, the initial adjustment range can be obtained to control the adjustment range of the z-axis adjustment stage 210.

[0036] The laser source 1, electro-optic modulator 2, fiber amplifier 3, and fiber optic pigtail 4 are sequentially connected via optical fibers. The output port of fiber optic pigtail 4 is located on the focal plane of collimating lens 6. Collimating lens 6, axial conical lens 7, axial conical lens 8, and eyepiece 9 are coaxially arranged. The back face of the cone angle of axial conical lens 7 is perpendicular to the optical axis of collimating lens 6, and axial conical lens 8 is symmetrically arranged with respect to axial conical lens 7. Light emitted from eyepiece 9 is incident on folding mirror 11, reflected by folding mirror 11, incident on folding mirror 12, reflected by folding mirror 12, and incident on Newton objective lens 13. The light finally exits parallel to Newton objective lens 13. The optical axis of the light exiting Newton objective lens 13 is parallel to the optical axis of the light exiting collimating lens 6.

[0037] The continuous laser output from the laser source 1 is transmitted to the electro-optic modulator 2 via optical fiber. The electro-optic modulator 2 modulates the amplitude or phase of the laser according to an external control signal to generate a modulated laser signal that meets communication requirements. The modulated laser signal is injected into the fiber amplifier 3 through the optical fiber. After being amplified by the fiber amplifier 3, it is output to the fiber pigtail 4 through the transmission fiber. After the defocusing state of the beam is adjusted by the z-axis adjustment stage 5, the light is transmitted to the collimating lens 6. The collimating lens 6 collimates the input beam into a parallel beam and outputs it to the axial cone lens 7. After being refracted by the axial cone lens 7, a conical beam is formed. This conical beam is incident on the axial cone lens 8. By adjusting the distance between the two axial cones, a Bessel-like beam with no diffraction characteristics is generated.

[0038] The Bessel-like beam is magnified by eyepiece 9 to match the beam aperture, and then incident on Newton objective lens 13 through folding mirror 11 and folding mirror 12. Finally, the Bessel-like beam is expanded and collimated by eyepiece 9, z-axis adjustment stage 10, folding mirror 11, folding mirror 12 and Newton objective lens 13 to form a long-distance transmission beam that is projected to a long-distance communication target.

[0039] A variable-distance, turbulence-resistant, dual-defocus Bessel-like optical communication method, comprising the following steps:

[0040] Step 1: Modeling: Using the optical design software Zemax, an optical system model of a variable-distance, anti-turbulence, dual-defocus control Bessel-like optical communication device is established. By simulating the individual and hybrid adjustment of the defocus of fiber optic pigtail 4 and eyepiece 9, different beam convergence distances and beam superposition region parameters are obtained, and beam output performance is analyzed. Thus, a dataset of different distances and beam superposition region parameters and corresponding defocus adjustment amounts of fiber optic pigtail 4 and eyepiece 9 is constructed.

[0041] Step 2, Communication: Based on the required communication distance and coverage area in the actual communication process, extract the defocusing data of the fiber optic pigtail 4 and eyepiece 9 corresponding to the required distance and area parameters from the dataset obtained in Step 1. Adjust the z-axis adjustment stage 5 and z-axis adjustment stage 10 to obtain the initial positions based on the extracted data. Then, laser communication is initiated. The laser source 1 outputs continuous laser light, which is modulated by the electro-optic modulator 2 according to the external control signal to generate a communication signal. After being amplified by the fiber optic amplifier 3, the signal is output from the fiber optic pigtail 4 fixed on the z-axis adjustment stage 5. After being collimated by collimating lens group 6, the emitted beam passes sequentially through the oppositely arranged axial conical mirror 7 and axial conical mirror 8, generating a Bessel-like beam with no diffraction characteristics. This beam continues to be incident on the eyepiece 9 controlled by the z-axis adjustment stage 10 for aperture adaptation and magnification. Then, it is guided by folding mirror 11 and folding mirror 12 to be incident on the Newton objective lens 13 and transmitted towards the communication target. At the receiving end, communication quality monitoring is simultaneously activated. By traversing the applied defocus amount and the feedback value of the communication receiving end, the optimal solution of defocus amount and antenna parameters is obtained, and the parameter implementation of the communication transmitting end is completed.

[0042] Step 3, Adjustment: To address the time-varying communication channel and the changing optical axis of the laser communication device, fine-tune the z-axis adjustment stage 5 to adjust the beam coverage range at a fixed distance, thereby achieving effective beam coverage. To address the time-varying communication distance, fine-tune the z-axis adjustment stage 10 to adjust the beam's defocus state, thereby achieving beam convergence and alignment at varying distances.

[0043] Step 4: Monitoring: Based on the optical power efficiency, received power, and bit error rate received by the laser communication receiver, make slight adjustments to the z-axis adjustment stage 5 and z-axis adjustment stage 10 in the device to obtain the optimal communication reception quality.

[0044] Step 5, Repeat: If there are drastic changes in communication distance and a significant decrease in communication quality, repeat steps 2-4.

[0045] This invention utilizes a variable-distance, turbulence-resistant, dual-defocus Bessel-like optical communication method to achieve near-ground variable-distance atmospheric laser communication links at 3.6km and 6.9km. The transmitting end employs a 1550nm band laser source with an output power of 30dBm, connected to the transmitting end of the communication device; the receiving position uses a 200mm diameter reflective antenna to receive the signal, which is then output to a high-speed power meter; the power meter sampling interval is 0.05s. Figure 6 , Figure 7 Synchronous emission of Gaussian beams and Bessel-like beams respectively Figure 5 The power fluctuation time-domain signal diagrams, generated by transmitting the beam over a 3.6km distance to the receiver and outputting to the power meter, represent the power fluctuations of a Gaussian beam and a Bessel-like beam under the same turbulent conditions over the same time interval. Figure 6 , Figure 7 It is known that Gaussian beams are subject to greater power fluctuations and greater fading depths due to turbulence. Bessel-like beams, on the other hand, exhibit smoother power fluctuations and smaller fading depths compared to Gaussian beams, resulting in higher link reliability. Figure 8 Synchronous emission of two types of beams: a Gaussian beam and a Bessel-like beam Figure 5 A statistical histogram of the output power fluctuation at the receiver over a period of time during a 3.6km spatial transmission. Figure 8 It can be seen that, compared with Gaussian beams and Bessel-like beams, power jitter is reduced and relatively concentrated when facing turbulent channels, and power stability is significantly improved.

[0046] Experiments show that the proposed invention can achieve variable distance laser communication through dual defocus control, while also having a certain ability to resist turbulence and attenuation.

Claims

1. A variable-distance, turbulence-resistant, dual-defocus control Bessel-like optical communication device, characterized in that... The device includes: a laser source (1), an electro-optic modulator (2), an optical fiber amplifier (3), an optical fiber pigtail (4), a z-axis adjustment stage one (5), a collimating lens (6), an axis conical lens one (7), an axis conical lens two (8), an eyepiece (9), a z-axis adjustment stage two (10), a folding mirror one (11), a folding mirror two (12), and a Newtonian objective lens (13). The laser source (1), electro-optic modulator (2), fiber amplifier (3), and fiber optic pigtail (4) are connected sequentially by optical fibers; the output port of the fiber optic pigtail (4) is located on the focal plane of the collimating lens (6); the collimating lens (6), axial conical lens one (7), axial conical lens two (8), and eyepiece (9) are coaxially arranged; the back face of the cone angle of axial conical lens one (7) is perpendicular to the optical axis of the collimating lens (6), and axial conical lens two (8) is symmetrically arranged with axial conical lens one (7); the light emitted from the eyepiece (9) is incident on folding mirror one (11), the light reflected by folding mirror one (11) is incident on folding mirror two (12), the light reflected by folding mirror two (12) is incident on Newton objective lens (13), and the light finally exits parallel through Newton objective lens (13); the optical axis of the light emitted through Newton objective lens (13) is parallel to the optical axis of the light emitted from collimating lens (6); The continuous laser output from the laser source (1) is transmitted to the electro-optic modulator (2) via optical fiber. The electro-optic modulator (2) modulates the amplitude or phase of the laser according to the external control signal to generate a modulated laser signal that meets the communication requirements. The modulated laser signal is injected into the fiber amplifier (3) through the optical fiber. After being amplified by the fiber amplifier (3), it is output to the fiber pigtail (4) through the transmission fiber. After the defocus state of the beam is adjusted by the z-axis adjustment stage (5), the light is transmitted to the collimating mirror (6). The collimating mirror (6) collimates the input beam into a parallel beam and outputs it to the first axial cone mirror (7). After being refracted by the first axial cone mirror (7), a conical beam is formed. The conical beam is incident on the second axial cone mirror (8). By adjusting the distance between the two axial cone mirrors, a Bessel-like beam with no diffraction characteristics is generated. The Bessel-like beam is magnified by the eyepiece (9) to match the beam aperture, and then incident on the Newton objective (13) through the first folding mirror (11) and the second folding mirror (12). Finally, the Bessel-like beam is expanded and collimated by the eyepiece (9), the second z-axis adjustment stage (10), the first folding mirror (11), the second folding mirror (12) and the Newton objective (13) to form a long-distance transmission beam, which is then projected to the long-distance communication target.

2. The variable-distance, turbulence-resistant, dual-defocus control Bessel-like optical communication device according to claim 1, characterized in that, The z-axis adjustment platform (5) includes a fixed clamping bracket (5-1) and a movable platform (5-2) that can slide along the z-axis. The fixed clamping bracket (5-1) is set on the movable platform (5-2). The output end of the fiber optic pigtail (4) is fixedly clamped on the fixed clamping bracket (5-1). By rotating the knob of the movable platform (5-2), the output port of the fiber optic pigtail (4) can be moved back and forth along the z-axis, thereby realizing defocus control.

3. The variable-distance, turbulence-resistant, dual-defocus control Bessel-like optical communication device according to claim 1, characterized in that, The z-axis adjustment platform 2 (10) includes a fixed clamping bracket 2 (10-1) and a movable platform 2 (10-2) that can slide along the z-axis. The fixed clamping bracket 2 (10-1) is set on the movable platform 2 (10-2). The outer lens barrel of the eyepiece (9) is fixedly embedded in the fixed clamping bracket 2 (10-1) to ensure that the optical axis of the eyepiece (9) is strictly coaxial with the main optical axis of the system. By rotating the knob of the movable platform 2 (10-2), the eyepiece (9) can move back and forth along the z-axis, thereby realizing defocus control.

4. A communication method for a Bessel-like optical communication device based on variable-distance anti-turbulence dual-defocus control, characterized in that... The method includes the following steps: Step 1, Modeling: Using the optical design software Zemax, an optical system model of a variable distance anti-turbulence dual defocus control Bessel-like optical communication device is established. By simulating the individual and hybrid adjustment of the defocus of the fiber optic pigtail (4) and the eyepiece (9), different beam convergence distances and beam superposition region parameters are obtained, and the beam output performance is analyzed. Thus, a dataset of different distances and beam superposition region parameters and corresponding fiber optic pigtail (4) and eyepiece (9) defocus adjustment amounts is constructed. Step 2, Communication: Based on the required communication distance and coverage area in the actual communication process, extract the defocusing data of the fiber optic pigtail (4) and eyepiece (9) corresponding to the required distance and area parameters from the dataset obtained in Step 1; adjust the z-axis adjustment stage one (5) and z-axis adjustment stage two (10) according to the extracted data to obtain the initial position; then start laser communication, the laser source (1) outputs continuous laser light, which is modulated by the electro-optic modulator (2) according to the external control signal to generate a communication signal; after the signal is amplified by the fiber optic amplifier (3), it is output by the fiber optic pigtail (4) fixed on the z-axis adjustment stage one (5); After being collimated by the collimating lens group (6), the beam passes through the axial conical mirror one (7) and axial conical mirror two (8) arranged opposite to each other, generating a Bessel-like beam with no diffraction characteristics. The beam continues to be incident on the eyepiece (9) controlled by the z-axis adjustment stage two (10) for aperture adaptation and magnification. Then, it is guided by the folding mirror one (11) and folding mirror two (12) to be incident on the Newton objective lens (13) and then transmitted to the communication target. At the receiving end, the communication quality monitoring is activated simultaneously. By traversing the applied defocus amount and the feedback value of the communication receiving end, the optimal solution of the defocus amount and antenna parameters is obtained, and the parameter implementation of the communication transmitting end is completed. Step 3, Adjustment: In response to the time-varying communication channel and the change of the optical axis of the laser communication device, fine-tune the z-axis adjustment stage one (5) to adjust the beam coverage range at a fixed distance, thereby achieving effective beam coverage; In response to the time-varying communication distance, fine-tune the z-axis adjustment stage two (10) to adjust the defocus state of the beam, thereby achieving beam convergence alignment under varying distances. Step 4, Monitoring: Based on the optical power efficiency, received power and bit error rate of the laser communication receiver, make slight adjustments to the z-axis adjustment stage one (5) and z-axis adjustment stage two (10) in the device to obtain the optimal communication reception quality; Step 5; Repeat: If there are drastic changes in communication distance and a significant decrease in communication quality, repeat steps 2-4.

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