Variable beam divergence angle laser communication terminal and rapid capturing method thereof

Abstract

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

Description

Technical Field

[0001] The invention belongs to the technical field of optical communication equipment, and in particular relates to a variable beam divergence angle laser communication terminal and a rapid capture method thereof. Background Art

[0002] Compared with the existing microwave communication technology, satellite laser communication technology has significant advantages such as high data rate, anti-interference and good confidentiality, and is an effective supplementary technical means for satellite communication in the future. Compared with the traditional microwave communication system, the laser communication system is superior to the traditional microwave communication system in that it uses the optical wave band as the information carrier (carrier 10~400THz), has a very high communication bandwidth, and has the outstanding advantages of light weight, small size and low power consumption. It is widely used in various occasions such as space, atmosphere, and underwater.

[0003] However, in order to meet the needs of long-distance communication, the transmission beam divergence angle of general laser communication terminals is designed to be small, and a near-diffraction limit design is adopted (for inter-satellite and satellite-to-ground communication). However, due to various factors such as the operating position, structural deformation, platform attitude, and time synchronization accuracy of the laser communication terminal flight platform, the aiming error is large during the laser communication link establishment process, the uncertainty area is large, and the scanning and capture time is long. Especially in the first link establishment, the error characteristics of the uncertainty area are unknown, making the initial link establishment more difficult.

[0004] Especially for beaconless laser communication terminals, since there is no independent large beam divergence beacon optical path outside the communication band, it is necessary to achieve coverage of uncertain areas through coarse and fine scanning of the composite axis. This method requires strict synchronization between the sender and the receiver, coordination of the target response action, and extremely short light spot response time, which makes two-way capture and link establishment difficult and has a low success rate.

[0005] However, current traditional terminals have the following problems: 1) low capture scanning efficiency, 2) long capture time, and 3) low capture success rate. Summary of the invention

[0006] In view of the above-mentioned problems, the present invention proposes a variable beam divergence laser communication terminal and a rapid capture method thereof. Through the variable beam divergence design based on a multi-core optical fiber splitter and supplemented by a corresponding capture and tracking strategy, the coverage efficiency of the beacon light of the traditional laser communication can be increased by 20 to 100 times, while the capture time can be significantly reduced (reduced to 1 / 5 to 1 / 10), and the efficiency of long-distance capture establishment is improved. It can be widely used in beacon light / signal light terminals with small beam divergence.

[0007] The above purpose is achieved through the following technical solutions: The present invention first provides a variable beam divergence laser communication terminal, comprising the following optical components: a main telescope, a precision tracking fast-reflecting mirror, a beam splitter, a filter, a beam splitter, a beacon receiving lens group, a beacon detector, a signal transmitting mirror group, an advance aiming fast-reflecting mirror, a signal receiving mirror group, a receiving optical fiber amplifier, a multi-core optical fiber splitter, an optical switch, and a transmitting optical fiber amplifier. The above optical components constitute a signal light transmitting optical path, a beacon light receiving optical path, and a signal light receiving optical path; wherein: The signal light emission optical path provides an emission light beam through optical fibers with different mode fields, and uses different paths of the emission mirror group to shape and emit the emission light with a variable beam divergence angle, including a main telescope, a precision tracking fast reflection mirror, a beam splitter, a signal emission mirror group, an advance aiming fast reflection mirror, a multi-core fiber splitter, an optical switch, and an emission fiber amplifier; the emission fiber amplifier completes the amplification of the input emission signal light and outputs it to the optical switch. Under the control of the command, the optical switch transmits the input amplified light beam to optical fibers with different mode fields / core diameters respectively, and inputs them to the discrete optical fiber ends of the multi-core fiber splitter through different optical fibers. Through the multi-core fiber splitter, multiple optical fibers with different core diameters are integrated into the same optical fiber ceramic core, and input to the optical antenna. The input light beam enters the signal emission mirror group, is reflected by the advance aiming fast reflection mirror after coaxiality adjustment, is tracked and reflected by the beam splitter and the precision tracking fast reflection mirror, enters the main telescope, and finally exits the terminal; The signal light receiving optical path is used to complete the collection, shaping, coupling and optical amplification of the input signal light, including a main telescope, a precision tracking fast-reflecting mirror, a spectroscope, a filter, a beam splitter, a signal receiving mirror group, and a receiving optical fiber amplifier; the light beam received by the main telescope is reflected by the precision tracking fast-reflecting mirror, and then split by the spectroscope, and then reflected by the filter and the beam splitter, and then incident on the signal receiving mirror group, and then focused and coupled to the receiving optical fiber, and then transmitted to the receiving optical fiber amplifier through the optical fiber for optical amplification, and then transmitted to the photoelectric detector for photoelectric demodulation; The beacon light receiving optical path is used to collect, shape and converge the input signal light, and use the image positioning detector to locate the target light spot, including a main telescope, a precision tracking fast reflection mirror, a spectrometer, a filter, a beam splitter, a beacon receiving lens group, and a beacon detector. The light beam received by the main telescope is reflected by the precision tracking fast reflection mirror, and then split by the spectrometer. After being reflected by the filter and the beam splitter, it is incident on the beacon receiving lens group and then focused on the beacon detector target surface to realize the identification and positioning of the light spot. The multi-core optical fiber splitter has two interfaces, a multi-path end and a small-path end.

[0008] Furthermore, the multi-channel end of the multi-core optical fiber splitter adopts N ceramic or metal optical fiber cores, each optical fiber core is independent of each other, and the number N is greater than or equal to 2; the multi-channel end of the multi-core optical fiber splitter is to integrate multiple optical fiber cores of the multi-channel end into the same optical fiber core to form M optical fiber cores on the same optical fiber connector of the multi-channel end, M is greater than or equal to 1 and M <N。

[0009] Furthermore, the deflection stroke L1 of the advance aiming quick-reflection mirror satisfies the condition: L1> , where dmax represents the adjustment distance of each optical fiber at the less-path end of the multi-core optical fiber splitter, is the focal length of the signal transmitting mirror group.

[0010] The present invention also provides a method for rapid capture using the above-mentioned variable beam divergence angle laser communication terminal, the method comprising the following steps: S1. Select beam divergence angle according to different working distances , and calculate the power that can be received by the target beacon detector at this beam divergence angle : , Where: P r Receive power for the detector; P t is the emission power of the emitting light source; or ot is the efficiency of the transmitting optical unit; L r is the spatial transmission loss, and its expression is: ,in D is the receiving aperture, i is the laser beam divergence angle, L is the link distance; or s The power loss caused by the channel; L PAT Power loss caused by PAT alignment mismatch; or or To receive the optical system efficiency; design Should be greater than P CCD-min , P CCD-min is the minimum working receiving power of the beacon detector, that is, the sensitivity threshold; S2. According to the beam divergence angle, the fiber mode field diameter of the output fiber corresponding to the less-path end of the multi-core fiber splitter can be calculated , , where F is the equivalent emission focal length of the signal light emission optical path, and the multi-channel end optical fiber mode field diameter J of the multi-core optical fiber splitter is obtained; S3. According to different beam divergence angles According to the requirements, the S1 and S2 processes are repeated respectively, and different multi-channel end optical fiber mode field diameters Ji are obtained, and the corresponding relationship is obtained ( )、( )…( ); S4: Based on the different multi-channel end optical fiber mode field diameters Ji and quantities, the optical fiber distribution topology with different mode field diameters on the optical fiber end face of the multi-core optical fiber splitter with few channels is designed, and the distribution topology includes but is not limited to concentric circle distribution, square distribution, and star distribution; S5. The distance from each fiber core to the geometric center of the fiber end face at the less-path end is di, and the angle relative to the geometric center of the fiber end face at the less-path end is Ωi ( ), the corresponding angular position of the advance aiming fast-reflection mirror is βi ( , η is the magnification of the advance aiming fast reflection mirror angle); S6. Laser terminal works according to different beam divergence angles The optical switch is controlled to switch to the corresponding ; S7. Control the advance aiming fast reflection mirror to deflect the angle position βi, and the laser terminal can emit a beam with a beam divergence angle; S8: The total travel Β of the advance aiming quick reflex mirror should satisfy Β>(βmax-βmin), wherein βmax is the maximum value of the rotation angle of the advance aiming quick reflex mirror, and βmin is the minimum value of the rotation angle of the advance aiming quick reflex mirror.

[0011] Beneficial Effects

[0012] The present invention realizes the function of precisely adjustable beam divergence of the laser communication terminal emission light beam by switching of optical switches, selection of multi-core optical fiber splitters and deflection of pre-aiming fast-reflection mirrors. The technology can be widely used in various terminals. Tests have shown that, compared with traditional laser communication systems, the light spot coverage efficiency of the present invention is improved by 20 to 100 times, and the capture time of both parties is reduced to 1 / 5 to 1 / 10 of the original time, which significantly improves the link establishment performance of the laser communication terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a system structure diagram of the present invention; Figure 2 It is a structural schematic diagram of the multi-core optical fiber splitter of the present invention; Explanation of the reference numerals in the figure: 1. Main telescope; 2. Precision tracking fast reflex mirror; 3. Beam splitter; 4. Filter; 5. Beam splitter; 6. Beacon receiving lens group; 7. Beacon detector; 8. Signal transmitting mirror group; 9. Advance aiming fast reflex mirror; 10. Signal receiving mirror group; 11. Receiving fiber amplifier; 12. Multi-core fiber splitter; 13. Optical switch; 14. Transmitting fiber amplifier. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0015] As attached Figure 1 As shown, a variable beam divergence laser communication terminal of this embodiment includes the following optical components: a main telescope 1, a precision tracking fast reflection mirror 2, a beam splitter 3, a filter 4, a beam splitter 5, a beacon receiving lens group 6, a beacon detector 7, a signal transmitting mirror group 8, an advance aiming fast reflection mirror 9, a signal receiving mirror group 10, a receiving optical fiber amplifier 11, a multi-core optical fiber splitter 12, an optical switch 13, and a transmitting optical fiber amplifier 14. The above optical components constitute a signal light transmitting optical path, a beacon light receiving optical path, and a signal light receiving optical path; wherein: The signal light emission optical path provides an emission light beam through optical fibers with different mode fields, and uses different paths of the emission mirror group to shape and emit the emission light with a variable beam divergence, including a main telescope 1, a precision tracking fast reflection mirror 2, a beam splitter 3, a signal emission mirror group 8, an advance aiming fast reflection mirror 9, a multi-core fiber splitter 12, an optical switch 13, and an emission fiber amplifier 14; the emission fiber amplifier 14 completes the amplification of the input emission signal light, and outputs it to the optical switch 13. Under the control of the command, the optical switch 13 transmits the input amplified light beam to optical fibers with different mode fields / core diameters respectively, and inputs them to the discrete optical fiber ends of the multi-core fiber splitter 12 through different optical fibers. Through the multi-core fiber splitter 12, a variety of optical fibers with different core diameters are integrated into the same optical fiber ceramic core, and input to the optical antenna. The input light beam enters the signal emission mirror group 8, and after being reflected by the advance aiming fast reflection mirror 9 after coaxiality adjustment, it is tracked and reflected by the beam splitter 3 and the precision tracking fast reflection mirror 2, and then enters the main telescope 1, and finally exits the terminal; The signal light receiving optical path is used to complete the collection, shaping, coupling and optical amplification of the input signal light, including a main telescope 1, a precision tracking fast reflex mirror 2, a beam splitter 3, a filter 4, a beam splitter 5, a signal receiving mirror group 10, and a receiving optical fiber amplifier 11; the light beam received by the main telescope 1 is reflected by the precision tracking fast reflex mirror 2, and then split by the beam splitter 3, and then reflected by the filter 4 and the beam splitter 5, and then incident on the signal receiving mirror group 10, and then focused and coupled to the receiving optical fiber, and then transmitted to the receiving optical fiber amplifier 11 through the optical fiber for optical amplification, and then transmitted to the photoelectric detector for photoelectric demodulation; The beacon light receiving optical path is used to collect, shape, and converge the input signal light, and use an image positioning detector to locate the target light spot. It includes a main telescope 1, a fine tracking fast steering mirror 2, a beam splitter 3, a filter 4, a beam splitter 5, a beacon receiving lens group 6, and a beacon detector 7. The beam received by the main telescope 1 is reflected by the fine tracking fast steering mirror 2, and then after being split by the beam splitter 3, it is incident on the beacon receiving lens group 6 after being reflected by the filter 4 and the beam splitter 5 and focused on the target surface of the beacon detector 7, realizing the identification and positioning of the light spot.

[0016] In this embodiment, the multi-core fiber splitter 12 has two interfaces, a multi-way end and a few-way end. The multi-way end uses N ceramic or metal fiber cores, and each fiber core is independent, with N≥2; the few-way end is to integrate multiple fiber cores at the multi-way end into M fiber cores on the same fiber connector at the few-way end, where M≥1 and M<N. In this embodiment, the forms of the fiber connectors on both sides of the multi-core fiber splitter 12 are not limited to FC interfaces, and can be various interfaces such as SMA, SC, LC, etc. For example, Figure 2 as shown, Figure 2 in the multi-core fiber splitter 12, M at the few-way end is 1, and there are N1, N2... Ni at the multi-way end.

[0017] In this embodiment, the deflection stroke L1 of the pre-aiming fast steering mirror 9 satisfies the condition: L1> , where dmax represents the adjustment distance of each fiber at the few-way end of the multi-core fiber splitter 12, and

[0018] is the focal length of the signal transmitting mirror group 8.

[0019] The method for fast acquisition using the above variable beam divergence angle laser communication terminal includes the following steps: S1. Select the beam divergence angle according to different working distances, and calculate the receivable power of this beam divergence angle reaching the target beacon detector: , where: P r is the detector receiving power; P t is the emission power of the emission light source; or ot is the efficiency of the emission optical unit; L r is the space transmission loss, and its expression is: ,in D is the receiving aperture, i is the laser beam divergence angle, L is the link distance; or s The power loss caused by the channel; L PAT Power loss caused by PAT alignment mismatch; or or To receive the optical system efficiency; Should be greater than P CCD-min , P CCD-min is the minimum operable receiving power of the beacon detector 7, i.e., the sensitivity threshold; S2. According to the beam divergence angle, the fiber mode field diameter of the output fiber corresponding to the less-path end of the multi-core fiber splitter 12 can be calculated. , , where F is the equivalent emission focal length of the signal light emission optical path, and the multi-channel end optical fiber mode field diameter J of the multi-core optical fiber splitter 12 is obtained; S3. According to different beam divergence angles According to the requirements, the S1 and S2 processes are repeated respectively, and different multi-channel end optical fiber mode field diameters Ji are obtained, and the corresponding relationship is obtained ( )、( )…( ); S4: Based on the different multi-channel end optical fiber mode field diameters Ji and quantities, the optical fiber distribution topology with different mode field diameters on the optical fiber end face of the multi-core optical fiber splitter 12 is designed, and the distribution topology includes but is not limited to concentric circle distribution, square distribution, and star distribution; S5. The distance from each fiber core to the geometric center of the fiber end face at the less-path end is di, and the angle relative to the geometric center of the fiber end face at the less-path end is Ωi ( ), the corresponding angular position of the advance aiming fast-reflection mirror 9 is βi ( , η is the magnification of the advance aiming fast reflection mirror angle); S6. Laser terminal works according to different beam divergence angles The optical switch 13 is controlled to switch to the corresponding ; S7. Control the advance aiming fast reflection mirror 9 to deflect the angle position βi, and the laser terminal will realize the light beam emission with the beam divergence angle; S8: The total stroke Β of the advance aiming quick reflex mirror 9 should satisfy Β>(βmax-βmin), wherein βmax is the maximum value of the advance aiming quick reflex mirror rotation angle, and βmin is the minimum value of the advance aiming quick reflex mirror rotation angle.

Claims

1. A variable beam divergence laser communication terminal, comprising the following optical components: a main telescope (1), a precision tracking fast-reflection mirror (2), a beam splitter (3), a filter (4), a beam splitter (5), a beacon receiving lens group (6), a beacon detector (7), a signal transmitting mirror group (8), an advance aiming fast-reflection mirror (9), a signal receiving mirror group (10), a receiving optical fiber amplifier (11), a multi-core optical fiber splitter (12), an optical switch (13), and a transmitting optical fiber amplifier (14), characterized in that: The above optical components constitute the signal light transmitting optical path, the beacon light receiving optical path, and the signal light receiving optical path; wherein: The signal light emission optical path provides an emission light beam through optical fibers with different mode fields, and uses different paths of an emission mirror group to shape the emission light and emit it with a variable beam divergence angle, comprising a main telescope (1), a precision tracking fast-reflecting mirror (2), a beam splitter (3), a signal emission mirror group (8), an advance aiming fast-reflecting mirror (9), a multi-core optical fiber splitter (12), an optical switch (13), and an emission optical fiber amplifier (14); the emission optical fiber amplifier (14) completes amplification of the input emission signal light and outputs it to the optical switch (13); under command control, the optical switch ( 13) The input amplified light beam is transmitted to optical fibers with different mode fields / core diameters respectively, and is input to the discrete optical fiber ends of the multi-core optical fiber splitter (12) through different optical fibers. The multiple optical fibers with different core diameters are integrated into the same optical fiber ceramic core through the multi-core optical fiber splitter (12), and input to the optical antenna. The input light beam enters the signal transmitting mirror group (8), is reflected by the coaxiality adjustment of the advance aiming fast reflection mirror (9), is tracked and reflected by the beam splitter (3) and the precision tracking fast reflection mirror (2), and enters the main telescope (1), and finally exits the terminal; The signal light receiving optical path is used to complete the collection, shaping, coupling and optical amplification of the input signal light, and comprises a main telescope (1), a precision tracking fast reflection mirror (2), a beam splitter (3), a filter (4), a beam splitter (5), a signal receiving mirror group (10), and a receiving optical fiber amplifier (11); the light beam received by the main telescope (1) is reflected by the precision tracking fast reflection mirror (2), split by the beam splitter (3), reflected by the filter (4) and the beam splitter (5), incident on the signal receiving mirror group (10), and then focused and coupled to the receiving optical fiber, and transmitted to the receiving optical fiber amplifier (11) through the optical fiber for optical amplification, and then transmitted to the photoelectric detector for photoelectric demodulation; The beacon light receiving optical path is used to collect, shape and converge the input signal light, and use the image positioning detector to locate the target light spot, comprising a main telescope (1), a precision tracking fast reflection mirror (2), a beam splitter (3), a filter (4), a beam splitter (5), a beacon receiving lens group (6), and a beacon detector (7). The light beam received by the main telescope (1) is reflected by the precision tracking fast reflection mirror (2), split by the beam splitter (3), reflected by the filter (4) and the beam splitter (5), and then incident on the beacon receiving lens group (6) and focused on the target surface of the beacon detector (7), thereby realizing the recognition and positioning of the light spot; The multi-core optical fiber splitter (12) has two interfaces: a multi-channel end and a small-channel end.

2. The variable beam divergence laser communication terminal according to claim 1, characterized in that: The multi-path end of the multi-core optical fiber splitter (12) uses N ceramic or metal optical fiber cores, each optical fiber core is independent of each other, and the number N is greater than or equal to 2; the multi-path end of the multi-core optical fiber splitter (12) is a multi-path end in which multiple optical fiber cores of the multi-path end are integrated into the same optical fiber core to form M optical fiber cores on the same optical fiber connector of the multi-path end, M is greater than or equal to 1 and M <N。 3. The variable beam divergence laser communication terminal according to claim 2, characterized in that: The deflection stroke L1 of the advance aiming quick-reflection mirror (9) satisfies the condition: L1> , where dmax represents the adjustment distance of each optical fiber at the less-path end of the multi-core optical fiber splitter (12), is the focal length of the signal transmitting mirror group (8).

4. A method for rapid capture using the variable beam divergence laser communication terminal according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: S1. Select beam divergence angle according to different working distances , and calculate the power that can be received by the target beacon detector at this beam divergence angle : ， Where: P r Receive power for the detector; P t is the emission power of the emitting light source; η ot is the efficiency of the transmitting optical unit; L r is the spatial transmission loss, and its expression is: ,in D is the receiving aperture, θ is the laser beam divergence angle, L is the link distance; η s The power loss caused by the channel; L PAT Power loss caused by PAT alignment mismatch; η or To receive the optical system efficiency; Should be greater than P CCD-min , P CCD-min is the minimum operable receiving power of the beacon detector (7), i.e., the sensitivity threshold; S2. According to the beam divergence angle, the fiber mode field diameter of the output fiber corresponding to the less-path end of the multi-core fiber splitter (12) can be calculated. , , where F is the equivalent emission focal length of the signal light emission optical path, and the multi-path end optical fiber mode field diameter J of the multi-core optical fiber splitter (12) is obtained; S3. According to different beam divergence angles According to the requirements, the S1 and S2 processes are repeated respectively, and different multi-channel end optical fiber mode field diameters Ji are obtained, and the corresponding relationship is obtained ( )、( )…( ); S4: Based on the different multi-channel end optical fiber mode field diameters Ji and quantities, designing the optical fiber distribution topology with different mode field diameters on the end face of the optical fiber at the few-channel end of the multi-core optical fiber splitter (12), the distribution topology including but not limited to concentric circle distribution, square distribution, and star distribution; S5. The distance from each fiber core to the geometric center of the fiber end face at the less-path end is di, and the angle relative to the geometric center of the fiber end face at the less-path end is Ωi, , the corresponding angular position of the advance aiming fast-reflection mirror (9) is βi, , η is the magnification of the advance aiming fast-reflection mirror angle; S6. Laser terminal works according to different beam divergence angles The optical switch (13) is controlled to switch to the corresponding ; S7. Control the advance aiming fast reflection mirror (9) to deflect the angle βi, and the laser terminal can emit a beam with a beam divergence angle; S8: The total travel Β of the advance aiming quick reflex mirror (9) should satisfy Β>(βmax-βmin), wherein βmax is the maximum value of the advance aiming quick reflex mirror rotation angle, and βmin is the minimum value of the advance aiming quick reflex mirror rotation angle.

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