Laser communication apparatus and method

Abstract

The application relates to the technical field of laser communication, and provides a laser communication device and method, which comprises, along an optical path: a beam expansion telescope configured to collimate emission of communication light and converging collection of spatial light; a dichroic filter configured to transmit communication wave bands; a transmitting / receiving system comprising a collimating lens group, a non-reciprocal unidirectional device and a filter detection module; the non-reciprocal unidirectional device is provided with a first port, a second port and a third port allowing unidirectional transmission of light beams; the first port is configured as a transmitting end, the second port is coupled with a transmission light path of the dichroic filter through the collimating lens group; and the third port is coupled with the filter detection module. In this way, high coaxial precision of laser transmission and reception and high isolation of the system can be considered, mutual crosstalk of transmitting and receiving light signals is avoided, the coupling efficiency of the light signals is improved, the device has high integration and low load weight, is beneficial to rapid arrangement and networking of ground laser communication, and improves the practicability and adaptability of ground laser communication.

Description

Technical Field

[0001] This invention relates to the field of laser communication technology, and in particular to a laser communication device and method. Background Technology

[0002] Against the backdrop of rapid information technology development, bandwidth, efficiency, deployment flexibility, and cost control of data transmission have become core requirements for the development of communication technology. As a traditional data transmission method, wired fiber optic networks once dominated long-distance and wide-range communication deployments. However, with the diversification of communication scenarios, wireless communication technology has become an important development direction in the field of communication due to its flexible deployment and strong adaptability. As a component of wireless communication, laser communication has become one of the solutions for solving high-bandwidth and long-distance wireless data transmission by virtue of the transmission characteristics of light waves.

[0003] Among related technologies, space laser communication has experienced rapid development due to its advantages such as narrow beam width, good directionality, small antenna size, large information capacity, low power consumption, small size, and light weight. From the perspective of transmission medium characteristics, light waves exhibit non-absorption, non-scattering, low loss, and anti-interference properties during space transmission. Compared to other wireless communication methods, laser communication offers higher cost-effectiveness and shows promising application prospects in communication networks across various scenarios, including terrestrial and space-based environments. Furthermore, to achieve bidirectional data interaction and information transmission in laser communication, an integrated optical path system is typically constructed through the combination of various optical components, simultaneously enabling laser signal transmission and reception to meet the needs of bidirectional communication.

[0004] However, practical research has revealed that existing laser communication implementation schemes still have insurmountable defects: the coaxiality of laser transmission and reception in laser communication determines the success or failure of the space link. In deployment and application, existing laser communication devices struggle to simultaneously achieve high transmit / receive coaxial accuracy and system isolation. While some schemes can achieve a certain degree of coaxiality adjustment, their low device integration and heavy load hinder rapid deployment. Other schemes, although capable of achieving optical path isolation through complex optical devices, have limited isolation effects and are prone to crosstalk between transmitted and received light, affecting communication stability. Furthermore, the coaxiality adjustment methods of existing laser communication devices are complex and have poor adaptability, failing to provide a reliable and efficient implementation scheme for large-scale laser communication networking, thus restricting the development and application of laser communication technology.

[0005] In view of the above problems, providing a laser communication device with higher coaxial accuracy and integration and lighter load has become an important technical challenge that urgently needs to be solved.

[0006] It should be clarified here that the above description is intended to facilitate understanding of the overall background of the present invention, and should not be construed as an admission or implication in any way that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] This invention provides a laser communication device and method to address the shortcomings of existing laser communication technologies, such as low coaxiality and integration of transmission and reception, and large load. It has the advantages of better coaxiality, higher integration, and lighter load.

[0008] This invention provides a laser communication device, comprising: arranged along the optical path:

[0009] A beam expander telescope is configured to collimate the emission of communication light and converge the beam of space light.

[0010] The dichroic separator is configured to transmit to the communication band.

[0011] A transmitting / receiving system includes a collimating lens group, a non-reciprocal unidirectional device, and a filtering and detection module; the non-reciprocal unidirectional device is provided with a first port, a second port, and a third port that allow unidirectional transmission of the light beam; the first port is configured as a transmitting end, the second port is coupled to the transmission light path of the dichroic separator through the collimating lens group, and the third port is coupled to the filtering and detection module.

[0012] According to a laser communication device provided by the present invention, an alignment module is further included, the alignment module being disposed on one side of the dichroic separator and forming a first optical receiving path and a second optical receiving path;

[0013] The first receiving optical path is parallel to the optical axis of the beam expander telescope;

[0014] The dichroic separator is also configured to reflect visible light and its reflected optical path is coupled to the second receiving optical path for reflecting visible light to the alignment module for imaging.

[0015] According to a laser communication device provided by the present invention, the alignment module includes a beam splitter and an alignment camera;

[0016] The beam splitter has a reflected light inlet and a transmitted light inlet. The reflected light inlet is coupled to the first receiving optical path to capture spatial light, and the transmitted light inlet is coupled to the second receiving optical path.

[0017] The alignment camera is coupled to the light outlet of the beam splitter.

[0018] A laser communication device according to the present invention further includes an adjustment device;

[0019] The beam expander, the dichroic spectrometer, the transmitting / receiving system, and the alignment module are all mounted on the adjustment device and are used to adjust the spatial attitude and optical axis orientation of the laser communication device.

[0020] According to the present invention, a laser communication device is provided.

[0021] The adjustment device is configured as a two-dimensional adjustment frame; and / or,

[0022] The dichroic beam splitter is configured to reflect beams in the 400nm–800nm ​​band and transmit beams in the 1550±100nm band. The beam splitter is configured to split beams in the 400nm–800nm ​​band at a ratio of 50:50 to complete bidirectional alignment.

[0023] According to a laser communication device provided by the present invention, the non-reciprocal unidirectional device is configured as a multimode fiber circulator, and the second port is coupled to the collimating lens group through a multimode fiber.

[0024] According to the present invention, a laser communication device is provided.

[0025] The multimode fiber is configured to be 62.5 μm; and / or,

[0026] The multimode fiber circulator is configured with the following characteristics: operating wavelength 400nm~1600nm, transmit / receive isolation better than 40dB, mode field diameter 200μm@1550nm, and numerical aperture NA=0.15.

[0027] According to a laser communication device provided by the present invention, the filtering and detection module includes: a filtering collimating lens group, a filter, a filtering coupling lens group, and a multimode fiber detector;

[0028] The filtering and collimating lens group is coupled to the third port and is used to collimate the received light.

[0029] The filter is coupled to the filtering collimating lens group to filter light of a preset wavelength;

[0030] The multimode fiber optic detector is coupled to the filter via the filter coupling lens group.

[0031] According to a laser communication device provided by the present invention, the beam expander telescope includes an objective lens group and an eyepiece group;

[0032] The objective lens assembly includes two first lenses, each configured with a system focal length of 200mm, an aperture of 55mm, and a system phase aberration RMS better than 42nm; and / or...

[0033] The eyepiece assembly includes two second lenses, which are configured with a system focal length of 40mm, an aperture of 15mm, and a system phase aberration RMS better than 42nm; and / or

[0034] The collimating lens group includes two third lenses, which are configured with the following characteristics: operating wavelength of 1400nm to 1600nm; focal length of 25.4mm; off-axis distance of 50.8mm; and aperture of 25.4mm.

[0035] The present invention also provides a laser communication method for use in any of the laser communication devices described above; comprising the following steps:

[0036] When the laser communication device is used to emit communication light, the transmitting / receiving system emits communication light through the first port of the non-reciprocal unidirectional device. The communication light exits from the second port, is collimated by the collimating lens group, and then enters the dichroic separator. Finally, it is emitted through the beam expander telescope.

[0037] When the laser communication device is used to receive space light, the space light passes through the beam expander telescope to shrink the beam, then through the dichroic separator. The transmitted light from the dichroic separator is incident on the collimating lens group, collimated, and then incident on the second port and exited from the third port. The filtering and detection module receives the light emitted from the third port and performs wavelength filtering and decoding.

[0038] According to a laser communication method provided by the present invention, spatial light is transmitted through space to an initial pointing and receiving position. The attitude of the laser communication device is adjusted so that the alignment module receives the spatial light for coarse alignment. Then, the alignment module receives the reflected light from the dichroic separator and the attitude of the laser communication device is adjusted to the position of the maximum energy receiving point of the alignment module to complete fine alignment.

[0039] The laser communication device and method provided by this invention, when the laser communication device is used to emit communication light, the transmitting / receiving system emits communication light through the first port of a non-reciprocal unidirectional device. The communication light exits from the second port and is collimated by a collimating lens group before entering a dichroic separator, and then is emitted through a beam expander. When the laser communication device is used to receive space light, the space light is reduced in size by the beam expander, then passes through a dichroic separator. The transmitted light from the dichroic separator enters the collimating lens group, is collimated, enters the second port, and exits from the third port. The filtering and detection module receives the light emitted from the third port and performs wavelength filtering and decoding.

[0040] Compared to related technologies, this invention achieves integrated construction of the laser transmission and reception path through the optical path coupling design of the beam expander, dichroic analyzer, and transmitting / receiving system, combined with the synergistic effect of non-reciprocal unidirectional devices and filtering detection modules. This simultaneously ensures high coaxial accuracy and high system isolation for both laser transmission and reception, overcoming the difficulty of achieving both high transmit / receive coaxiality and high isolation in existing solutions. The unidirectional transmission characteristics of the non-reciprocal unidirectional devices ensure that the transmitted light is emitted along a preset optical path and the received light is directionally transmitted to the filtering detection module, avoiding crosstalk between the transmitted and received signals and improving the coupling efficiency of the optical signals. Combined with the wavelength filtering function of the filtering detection module, this further enhances the system isolation effect and detection sensitivity. At the same time, the overall device adopts a modular optical component combination design, simplifying the optical path adjustment logic, improving the integration of the device, and reducing the load weight. This not only facilitates the rapid deployment and networking of terrestrial laser communication but also maintains stable communication performance in complex ground environments, providing a reliable guarantee for the establishment and stable transmission of laser communication links, and improving the practicality and adaptability of terrestrial laser communication. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the structure of the laser communication device provided in an embodiment of the present invention.

[0043] Figure 2 This is a schematic diagram of the structure of the filtering detection module provided in an embodiment of the present invention.

[0044] Figure label:

[0045] 10. Beam expander telescope; 11. Objective lens group; 12. Eyepiece group; 20. Dichroic separator; 30. Transmitter / receiver system; 31. Collimating lens group; 32. Non-reciprocal unidirectional device; 321. First port; 322. Second port; 323. Third port; 33. Filtering detection module; 331. Filtering collimating lens group; 332. Filter; 333. Filtering coupling lens group; 334. Multimode fiber detector; 34. Multimode fiber; 40. Alignment module; 401. First receiving optical path; 402. Second receiving optical path; 41. Beam splitter; 42. Alignment camera; 43. Adjustment device. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0047] To better understand the laser communication device and method provided in the embodiments of the present invention, its application background is first introduced. Space laser communication, due to its advantages such as narrow beam width, good directionality, small antenna size, large information capacity, low power consumption, small size, and light weight, has become an important component of wireless communication. From the perspective of transmission medium characteristics, light waves have the characteristics of no absorption, no scattering, low loss, and anti-interference in space transmission. Compared with other wireless communication methods, laser communication has a higher cost-effectiveness and shows good application prospects in communication networks in various scenarios such as ground and space. Meanwhile, to achieve bidirectional data interaction and information transmission in laser communication, an integrated optical path system is generally constructed by combining various optical components to simultaneously realize the transmission and reception functions of laser signals, meeting the needs of bidirectional communication.

[0048] However, practical research has revealed that existing laser communication implementation schemes still have insurmountable defects: the coaxiality of laser transmission and reception in laser communication determines the success or failure of the space link. In deployment and application, existing laser communication devices struggle to simultaneously achieve high transmit / receive coaxial accuracy and system isolation. While some schemes can achieve a certain degree of coaxiality adjustment, their low device integration and heavy load hinder rapid deployment. Other schemes, although capable of achieving optical path isolation through complex optical devices, have limited isolation effects and are prone to crosstalk between transmitted and received light, affecting communication stability. Furthermore, the coaxiality adjustment methods of existing laser communication devices are complex and have poor adaptability, failing to provide a reliable and efficient implementation scheme for large-scale laser communication networking, thus restricting the development and application of laser communication technology.

[0049] In view of the above problems, embodiments of the present invention provide a laser communication device and method, which have the advantages of better coaxiality, higher integration and lighter load.

[0050] The following is combined with Figure 1 and Figure 2 The laser communication device and method of the present invention are described.

[0051] Reference Figure 1 and Figure 2A laser communication device includes a beam expander 10, a dichroic beam splitter 20, and a transmit / receive system 30. The beam expander 10 is configured to collimate and emit communication light and to converge spatial light. The dichroic beam splitter 20 is configured to transmit light in the communication band. The transmit / receive system 30 includes a collimating lens group 31, a non-reciprocal unidirectional device 32, and a filtering and detection module 33. The non-reciprocal unidirectional device 32 has a first port 321, a second port 322, and a third port 323 that allow unidirectional beam transmission. The first port 321 is configured as the transmitting end. The second port 322 is coupled to the transmission path of the dichroic beam splitter 20 through the collimating lens group 31. The third port 323 is coupled to the filtering and detection module 33.

[0052] In practical applications, when the laser communication device is used to transmit communication light, the transmitting / receiving system 30 transmits communication light through the first port 321 of the non-reciprocal unidirectional device 32. The communication light exits from the second port 322, is collimated by the collimating lens group 31, and then enters the dichroic separator 20, and is then emitted through the beam expander telescope 10. When the laser communication device is used to receive spatial light, the spatial light is reduced in size by the beam expander telescope 10, and then passes through the dichroic separator 20. The transmitted light from the dichroic separator 20 enters the collimating lens group 31, is collimated, enters the second port 322, and exits from the third port 323. The filtering and detection module 33 receives the light emitted from the third port 323 and performs wavelength filtering and decoding.

[0053] Compared to related technologies, the optical path coupling design of the beam expander telescope 10, dichroic spectrometer 20, and transmit / receive system 30, combined with the synergistic effect of the non-reciprocal unidirectional device 32 and the filter detection module 33, achieves the integrated construction of the laser transmit / receive optical path. This simultaneously ensures high coaxial accuracy and high system isolation for laser transmission and reception, solving the problem of difficulty in achieving both high transmit / receive coaxiality and high isolation in existing solutions. The unidirectional transmission characteristic of the non-reciprocal unidirectional device 32 ensures that the transmitted light is emitted along a preset optical path and the received light is directionally transmitted to the filter detection module 33, thus avoiding the need for simultaneous transmission and reception. The crosstalk between optical signals improves the coupling efficiency of optical signals. Combined with the wavelength filtering function of the filter detection module 33, the system isolation effect and detection sensitivity are further enhanced. At the same time, the overall device adopts a modular optical component combination design, which simplifies the optical path adjustment logic, improves the integration of the device, and reduces the load weight. This not only facilitates the rapid deployment and networking of terrestrial laser communication, but also maintains stable communication performance in complex ground environments. It provides a reliable guarantee for the establishment and stable transmission of laser communication links, and improves the practicality and adaptability of terrestrial laser communication.

[0054] In one example of the present invention, the laser communication device further includes an alignment module 40, which has a first receiving optical path 401 and a second receiving optical path 402. The first receiving optical path 401 is parallel to the optical axis of the beam expander telescope 10, and the dichroic separator 20 is configured to reflect visible light and its reflected optical path is coupled to the second receiving optical path 402 for reflecting visible light to the alignment module 40 for imaging.

[0055] With this setup, the laser communication device is adjusted to align the first receiving optical path 401 with the transmission optical path of the spatial light. The alignment module 40 receives the spatial light for coarse alignment. Then, the first receiving optical path 401 is blocked. When the spatial light passes through the beam expander 10 and then the dichroic separator 20, the communication band is transmitted into the transmitting / receiving system 30, while the visible band is reflected and enters the alignment module 40 through the second receiving optical path 402 for imaging. The laser communication device is then finely adjusted, and finally, the light is adjusted to the position of the maximum energy receiving point of the alignment module 40 to achieve fine alignment. This allows for rapid target finding and alignment, and ensures the consistency between the alignment reference and the communication optical axis. It provides an optical path foundation for high coaxial accuracy of laser transmission and reception, eliminating the need for a complex alignment optical path structure, simplifying the overall optical path design of the device, and improving integration.

[0056] Understandably, the specific specifications of each component in this laser communication device need to be flexibly adjusted and selected based on actual application scenarios, such as communication distance, transmission bandwidth, and environmental adaptability. The band adaptability and performance indicators of various optical devices can be specifically designed to meet the actual deployment requirements of terrestrial laser communication and adapt to the bidirectional communication needs in different scenarios. The following will describe each component in detail with reference to the accompanying drawings.

[0057] In one example of the present invention, the beam expander telescope 10 includes an objective lens group 11 and an eyepiece group 12; wherein, the objective lens group 11 is configured as a long focal length structure to realize long focal length beam convergence of spatial light and long focal length collimation and beam expansion of communication light; the eyepiece group 12 is configured as a short focal length structure and coupled with the objective lens group 11 to complete short focal length optical path calibration of communication light and short focal length beam diameter adaptation of spatial light. The two work together to realize collimated transmission of communication light and beam convergence of spatial light, ensuring efficient transmission of optical signals in the transmission and reception links.

[0058] In detail, objective lens group 11 includes two first lenses, and the two first lenses satisfy the following conditions: system focal length 200mm, aperture 55mm, and system phase difference RMS better than 42nm. Eyepiece group 12 includes two second lenses, and the two second lenses satisfy the following conditions: system focal length 40mm, aperture 15mm, and system phase difference RMS better than 42nm.

[0059] In one example of the present invention, the dichroic separator 20 is configured to reflect light in the 400nm to 800nm ​​band, transmit light in the 1550±100nm band, have a reflectivity of 95%, a transmittance of 95%, and a reflective surface profile accuracy RMS better than 0.03λ@632.8nm.

[0060] In one example of the present invention, in the transmitting / receiving system 30, the collimating lens group 31 includes two third lenses, and the third lenses are configured to have a working wavelength of 1400nm to 1600nm, a focal length of 25.4mm, an off-axis distance of 50.8mm, and an aperture of 25.4mm.

[0061] In one example of the present invention, the non-reciprocal unidirectional device 32 is configured as a multimode fiber circulator, with the second port 322 coupled to the collimating lens group 31 via a multimode fiber 34. The multimode fiber circulator is a non-reciprocal unidirectional three-port device used to achieve unidirectional cyclic transmission of optical signals with high reverse isolation. The first port 321, the second port 322, and the third port 323 correspond to the three ports on the multimode fiber circulator. A signal input from the first port 321 will be output from the second port 322 with extremely low loss, and a signal input from the second port 322 will be output from the third port 323 with extremely low loss. However, the light input from the second port 322 has significant loss at the first port 321, and the light input from the third port 323 has significant loss at both the second port 322 and the first port 321. This achieves sequential unidirectional transmission of the optical signal among the three ports, defining the transmission path of the received and received optical signals, enhancing the isolation effect, and reducing crosstalk.

[0062] In detail, the multimode fiber circulator is configured to operate at wavelengths of 400nm to 1600nm, with a transmit / receive isolation better than 40dB, a mode field diameter of 200μm@1550nm, and a numerical aperture NA=0.15; the multimode fiber 34 uses 62.5μm multimode fiber 34.

[0063] It should be noted here that the mode field diameter (MFD) is used to describe the effective spot size of the fundamental mode optical field on the cross-section of the optical fiber.

[0064] In one example of the present invention, the filtering detection module 33 includes a filtering collimating lens group 331, a filter 332, a filtering coupling lens group 333, and a multimode fiber detector 334; wherein, the filtering collimating lens group 331 is coupled to the third port 323 for collimating the received light, the filter 332 is coupled to the filtering collimating lens group 331 for filtering light of a preset wavelength; the multimode fiber detector 334 is coupled to the filter 332 through the filtering coupling lens group 333 for receiving and decoding optical signals.

[0065] With this configuration, the filtering and collimating lens group 331 can collimate the optical signal output from the third port 323. The collimated optical signal is then incident on the filter 332. The filter 332 can filter the optical signal of the preset communication wavelength, filtering out ambient stray light and non-target band interference light, further improving the system's anti-interference capability and optical path isolation. The filtering and coupling lens group 333 then couples the filtered optical signal to the multimode fiber detector 334, ensuring concentrated transmission of optical signal energy. Together with the multimode fiber detector 334, it realizes the reception and decoding of the optical signal, ensuring the purity and intensity of the received signal.

[0066] Furthermore, the filter 332 is configured to be detachable, so that the filter 332 with the corresponding preset wavelength can be replaced according to the band requirements of the actual communication scenario, adapting to the transmission requirements of different communication bands, improving the scenario adaptability and reusability of the device, and enhancing the practicality and flexible adaptability of the device in the large-scale networking of terrestrial laser communication.

[0067] In detail, the filter collimating lens group 331 and the filter coupling lens group 333 are configured with: a system focal length of 10mm, a system aperture of 8mm, a coating wavelength of 1050nm to 1620nm, and a transmittance better than 98%. The filter 332 is configured as a narrowband filter with a transmission loss of no more than 1dB and replaceable according to the wavelength range. The multimode fiber detector 334 is configured with: a fiber core diameter of 105μm, a numerical aperture of 0.22, and a multimode fiber detector size of 80μm (with a converging lens added in the pre-stage).

[0068] In one example of the present invention, the alignment module 40 includes a beam splitter 41 and an alignment camera 42; wherein the beam splitter 41 is provided with a reflected light inlet and a transmitted light inlet, wherein the reflected light inlet is coupled to a first receiving light path 401 for capturing spatial light, and the transmitted light inlet is coupled to a second receiving light path 402 for receiving visible light reflected by the dichroic spectrometer 20; the alignment camera 42 is coupled to the light outlet of the beam splitter 41.

[0069] With this configuration, by adjusting the spatial position and optical axis orientation of the laser communication device, the reflected light inlet of the beam splitter 41 can capture the spatial light transmitted by the first receiving optical path 401. The spatial light enters the alignment camera 42 through the light outlet of the beam splitter 41, thus providing a large field of view support for initial target acquisition, assisting in the rapid locking of the communication target, and completing coarse positioning. After coarse positioning is completed, the first receiving optical path 401 is blocked. When the spatial light passes through the dichroic separator 20 after being reduced by the beam expander telescope 10, the visible band is reflected and enters the alignment module 40 through the second receiving optical path 402 to form an image. The laser communication device is then finely adjusted until the maximum energy receiving point of the alignment camera 42 is reached, achieving fine alignment. This provides a precise coaxial alignment reference for the alignment camera 42, ensuring that the communication optical axis and the receiving optical axis are highly coincident.

[0070] Furthermore, the laser communication device also includes an adjustment device 43; the beam expander 10, dichroic analyzer 20, transmitting / receiving system 30 and alignment module 40 are all mounted on the adjustment device 43, and are used to adjust the spatial attitude and optical axis orientation of the laser communication device.

[0071] This configuration ensures that the relative installation positions and optical path coupling relationships of the beam expander, dichroic spectrometer, transmitting / receiving system, and alignment module remain constant. During the process of adjusting the optical axis of the device by the adjustment device 43, the relative positions of the internal optical components do not shift. At the same time, the integrated adjustment method simplifies the optical axis alignment operation process, enabling the device's main optical axis to be aligned with the target quickly and accurately. This improves the efficiency and stability of establishing a space laser communication link and better meets the application requirements of rapid deployment and precise alignment of ground-based laser communication.

[0072] In detail, the beam splitter 41 is configured with a wavelength of 400nm to 800nm, an incident angle of 45 degrees, an energy splitting ratio of 50:50, an error ratio of ±12%, and a system wave phase difference RMS better than 306nm. The alignment camera 42 is configured with a focal length of 300mm, a system wave phase difference RMS better than 42nm, and a field of view of ±1.5°. The adjustment device 43 is configured as a two-dimensional or three-dimensional adjustment frame with a mounting platform size of 200mm, an adjustment accuracy of 0.0002°, and a load-bearing capacity of 30kg.

[0073] It should be noted that the parameters of each optical device are not limited to the examples above. The parameters of each optical device can be flexibly adjusted according to actual needs such as communication distance, transmission bandwidth, target band, and environmental interference resistance.

[0074] Furthermore, the communication device is assembled in the following manner:

[0075] Step 1: First, adjust the collimating lens group 31 and the multimode fiber circulator. Connect the signal light to the first port 321 of the multimode fiber circulator through a flange and emit the signal light. The signal light is emitted from the second port 322 after passing through the multimode fiber circulator. Adjust the position of the second port 322 and the collimating lens group 31. Detect the optimal position of the second port 322 and the collimating lens group 31 through Fourier transform, and then tighten it.

[0076] Step 2: Coaxial alignment of camera 42 and collimating lens group 31 from Step 1:

[0077] a) After placing the dichroic separator 20 in front of the device that was adjusted in step 1, adjust the dichroic separator 20 so that the light spot is emitted from the center of the dichroic separator 20, and fix the dichroic separator 20 and the device that was adjusted in step 1.

[0078] b) Place a corner prism on the output optical path of the dichroic splitter 20 (the corner prism reflects the image or beam back to the original direction through three reflections), turn on the laser source at the first port 321 of the multimode fiber circulator, the collimated spot is reflected back by the corner prism, then reflected by the dichroic splitter 20 and enters the beam splitter 41, and is transmitted to the alignment camera 42 for imaging. Adjust the position of the alignment camera 42 so that the image point is near the center position of the alignment camera 42, and record this tracking position.

[0079] c) Then tighten the alignment with camera 42 to complete the establishment of the system's optical axis.

[0080] The laser communication method provided by the present invention is described below. The laser communication method described below can be referred to in correspondence with the laser communication device described above.

[0081] A laser communication method includes the following steps:

[0082] Step S1: When the laser communication device is used to emit communication light, the transmitting / receiving system 30 emits communication light through the first port 321 of the non-reciprocal unidirectional device 32. The communication light is emitted from the second port 322 and collimated by the collimating lens group 31 before entering the dichroic separator 20, and then emitted through the beam expander telescope 10.

[0083] Step S2: When the laser communication device is used to receive spatial light, the spatial light is reduced by the beam expander telescope 10 and then passes through the dichroic separator 20. The transmitted light from the dichroic separator 20 is incident on the collimating lens group 31, collimated, and then incident on the second port 322 and exited from the third port 323. The filtering and detection module 33 receives the light emitted from the third port 323 and performs wavelength filtering and decoding.

[0084] Furthermore, step S2 also includes: the spatial light is transmitted through space to the initial pointing receiving position, the attitude of the laser communication device is adjusted so that the alignment module 40 receives the spatial light for coarse alignment, and then the alignment module 40 receives the reflected light from the dichroic unit 20, and the attitude of the laser communication device is adjusted to the position of the maximum energy receiving point of the alignment module 40 to complete the fine alignment.

[0085] In detail, the spatial position of the laser communication device is adjusted by the adjustment device 43 so that the reflected light inlet of the beam splitter 41 can capture the spatial light transmitted by the first receiving optical path 401. The spatial light enters the alignment camera 42 through the light outlet of the beam splitter 41 to form an image, thus completing the coarse positioning. After the coarse positioning is completed, the first receiving optical path 401 is blocked. When the spatial light passes through the dichroic separator 20 after being reduced by the beam expander telescope 10, the visible band is reflected and enters the alignment module 40 through the second receiving optical path 402 to form an image. The laser communication device is then finely adjusted by the adjustment device 43 until the position of the maximum energy receiving point of the alignment camera 42 is reached, thus achieving fine alignment.

[0086] It is understood that, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples.

[0087] The laser communication device and method provided in this invention, through the optical path coupling design of the beam expander telescope 10, dichroic spectrometer 20, and transmitting / receiving system 30, combined with the synergistic effect of non-reciprocal unidirectional device 32 and filtering detection module 33, achieves the integrated construction of laser transmission and reception optical paths. This simultaneously ensures high coaxial accuracy of laser transmission and reception and high system isolation, solving the defect in existing solutions where high transmission / reception coaxiality and high isolation are difficult to achieve simultaneously. The unidirectional transmission characteristic of non-reciprocal unidirectional device 32 enables the emitted light to be emitted along a preset optical path and the received light to be directionally transmitted to the filtering detection module 33. This design avoids crosstalk between received and emitted signals and improves the coupling efficiency of optical signals. Combined with the wavelength filtering function of the filter detection module 33, it further enhances the system isolation effect and detection sensitivity. At the same time, the overall device adopts a modular optical component combination design, which simplifies the optical path adjustment logic, improves the integration of the device, and reduces the load weight. This not only facilitates the rapid deployment and networking of terrestrial laser communication, but also maintains stable communication performance in complex ground environments, providing a reliable guarantee for the establishment and stable transmission of laser communication links, and improving the practicality and adaptability of terrestrial laser communication.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser communication device, characterized in that, Including those arranged along the optical path: The beam expander (10) is configured to collimate the transmission of communication light and converge the beam of space light. The dichroic separator (20) is configured to transmit to the communication band; The transmitting / receiving system (30) includes a collimating lens group (31), a non-reciprocal unidirectional device (32), and a filtering and detection module (33); the non-reciprocal unidirectional device (32) is provided with a first port (321), a second port (322), and a third port (323) that allow unidirectional transmission of the beam; the first port (321) is configured as the transmitting end, the second port (322) is coupled to the transmission optical path of the dichroic separator (20) through the collimating lens group (31); the third port (323) is coupled to the filtering and detection module (33); It also includes an alignment module (40), which is disposed on one side of the color separator (20) and forms a first receiving optical path (401) and a second receiving optical path (402). The first receiving optical path (401) is parallel to the optical axis of the beam expander telescope (10); The dichroic separator (20) is also configured to reflect visible light and its reflected light path is coupled to the second receiving light path (402) for reflecting visible light to the alignment module (40) for imaging. The alignment module (40) includes a beam splitter (41) and an alignment camera (42). The beam splitter (41) has a reflected light inlet and a transmitted light inlet. The reflected light inlet is coupled to the first receiving optical path (401) for capturing spatial light, and the transmitted light inlet is coupled to the second receiving optical path (402). The alignment camera (42) is coupled to the light outlet of the beam splitter (41).

2. The laser communication device according to claim 1, characterized in that, It also includes an adjustment device (43); The beam expander (10), the dichroic spectrometer (20), the transmitter / receiver system (30), and the alignment module (40) are all mounted on the adjustment device (43) for adjusting the spatial attitude and optical axis orientation of the laser communication device.

3. The laser communication device according to claim 2, characterized in that, The non-reciprocal unidirectional device (32) is configured as a multimode fiber circulator, and the second port (322) is coupled to the collimating lens group (31) via a multimode fiber (34); and / or The adjustment device (43) is configured as a two-dimensional adjustment frame; and / or, The dichroic separator (20) is configured to reflect beams in the 400nm to 800nm ​​band and transmit beams in the 1550±100nm band. The beam splitter (41) is configured to have a beam splitting ratio of 50:50 in the 400nm to 800nm ​​band for bidirectional alignment.

4. The laser communication device according to claim 3, characterized in that, The multimode fiber (34) is configured to be 62.5 μm; and / or, The multimode fiber circulator is configured with the following characteristics: operating wavelength 400nm~1600nm, transmit / receive isolation greater than 40dB, mode field diameter 200μm@1550nm, and numerical aperture NA=0.

15.

5. The laser communication device according to claim 1, characterized in that, The filtering detection module (33) includes: a filtering collimating lens group (331), a filter (332), a filtering coupling lens group (333), and a multimode fiber detector (334). The filtering collimating lens group (331) is coupled to the third port (323) for collimating the received light; The filter (332) is coupled to the filter collimating lens group (331) to filter light of a preset wavelength; The multimode fiber detector (334) and the filter (332) are coupled through the filter coupling lens group (333).

6. The laser communication device according to claim 5, characterized in that, The beam expander telescope (10) includes an objective lens group (11) and an eyepiece group (12). The objective lens group (11) includes two first lenses, which are configured with a system focal length of 200 mm, an aperture of 55 mm, and a system phase difference RMS greater than 42 nm; and / or, The eyepiece assembly (12) includes two second lenses, which are configured such that: the system focal length is 40 mm, the aperture is 15 mm, and the system phase difference RMS is greater than 42 nm; and / or, The collimating lens group (31) includes two third lenses, which are configured to have a working wavelength of 1400nm to 1600nm, a focal length of 25.4mm, an off-axis distance of 50.8mm, and an aperture of 25.4mm.

7. A laser communication method, characterized in that, For use in the laser communication device as described in any one of claims 1 to 6; comprising the following steps: When the laser communication device is used to emit communication light, the transmitting / receiving system (30) emits communication light through the first port (321) of the non-reciprocal unidirectional device (32). The communication light is emitted from the second port (322) and collimated by the collimating lens group (31) before entering the dichroic separator (20), and then emitted through the beam expander telescope (10). When the laser communication device is used to receive spatial light, the spatial light is reduced by the beam expander telescope (10) and then passes through the dichroic separator (20). The transmitted light from the dichroic separator (20) is incident on the collimating lens group (31), collimated, and then incident on the second port (322) and exited from the third port (323). The filtering and detection module (33) receives the light emitted from the third port (323) and performs wavelength filtering and decoding. The spatial light is transmitted through space to the initial pointing receiving position. The attitude of the laser communication device is adjusted so that the reflected light inlet of the beam splitter (41) can capture the spatial light transmitted by the first receiving optical path (401). The spatial light enters the alignment camera (42) through the light outlet of the beam splitter (41) to form an image, thus completing the coarse alignment. After the coarse alignment is completed, the first receiving optical path (401) is blocked. When the spatial light passes through the beam expander (10) and then through the dichroic separator (20), the visible band is reflected and enters the alignment module (40) through the second receiving optical path (402) to form an image. The laser communication device is then finely adjusted until the maximum energy receiving point of the alignment camera (42) is reached, thus completing the fine alignment.

Images