CN218958917U - Space optical communication system - Google Patents
Space optical communication system Download PDFInfo
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- CN218958917U CN218958917U CN202223526778.5U CN202223526778U CN218958917U CN 218958917 U CN218958917 U CN 218958917U CN 202223526778 U CN202223526778 U CN 202223526778U CN 218958917 U CN218958917 U CN 218958917U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The application belongs to the technical field of space optical communication, and particularly discloses a space optical communication system, which aims to solve the problem of small information capacity of the traditional space optical communication technology. The space optical communication system comprises a signal transmitting end and a signal receiving end, wherein the signal transmitting end comprises a light source module, a first beam splitting module, an information loading module, a column vector light beam generating module and a beam combining module, the light source module is used for generating laser light beams, the first beam splitting module is used for splitting the laser light beams into multiple paths of light beams, the information loading module is used for loading signals for each path of light beams to obtain multiple paths of transmitting end signal beams carrying signals, each path of transmitting end signal beam corresponds to one path of transmitting end optical channel, the column vector light beam generating module is used for respectively converting each path of transmitting end signal beam into different column vector light beams, and the beam combining module is used for converging each path of column vector light beams to form single beam transmitting end signal beams and transmitting the single beam transmitting end signal beams to the signal receiving end.
Description
Technical Field
The application relates to the technical field of space optical communication, in particular to a space optical communication system.
Background
The spatial laser communication technology uses laser light as carrier wave transmission information, and generally uses physical parameters such as wavelength, frequency, time, amplitude, phase and polarization of an optical signal to carry out signal mounting. Conventional information carriers are already in a fully developed state for later mass-communication. In order to expand the information capacity in free space communications, laser polarization multiplexing devices are used, and conventional laser polarization multiplexing devices generally adopt orthogonal linearly polarized light as a carrier of information, so as to transmit signals. At this point there will be two signals in the channel. The upper capacity limit of such systems is also limited to this in order to avoid cross-talk between signals.
Disclosure of Invention
The embodiment of the application provides a space optical communication system, which aims to solve the technical problem of small information capacity of the space optical communication technology in the prior art.
The spatial optical communication system provided by the embodiment of the application comprises a signal transmitting end and a signal receiving end, wherein the signal transmitting end comprises a light source module, a first beam splitting module, an information loading module, a column vector beam generating module and a beam combining module,
the light source module is used for generating a laser beam,
the first beam splitting module is used for splitting the laser beam into multiple paths of beams,
the information loading module is used for loading signals for each path of light beam to obtain a plurality of paths of signal light beams of the transmitting end carrying the signals, each path of signal light beam of the transmitting end corresponds to one path of optical channel of the transmitting end,
the column vector beam generating module is used for respectively converting each path of signal beam at the transmitting end into different column vector beams,
the beam combination module is used for converging each path of column vector beam to form a single beam transmitting end signal beam and transmitting the single beam transmitting end signal beam to the signal receiving end.
According to an embodiment of the present application, the post-vector light beam generating module includes a polarizer and a vortex wave plate that are disposed along a propagation direction of an emission-end signal light beam of each path of emission-end optical channel, and different combinations of polarization directions of the polarizers of different emission-end optical channels and orders and fast axis directions of the vortex wave plate correspond to different post-vector light beams.
According to any of the embodiments described above, the number of optical channels at the transmitting end is an even number, and the two optical channels at the transmitting end are a group;
the polarization directions of the polarizers of the optical channels at different emission ends in the same group are mutually perpendicular, vortex wave plates are shared among the optical channels at different emission ends in the same group, and the fast axis direction of the vortex wave plates is the same as the polarization direction of the polarizer of one of the optical channels at the emission end;
the order of the vortex wave plates is different between different groups.
According to any of the foregoing embodiments of the present application, the emitter optical channel comprises a first emitter optical channel, a second emitter optical channel, a third emitter optical channel and a fourth emitter optical channel,
the polarization directions of the polarizers of the first transmitting end optical channel and the second transmitting end optical channel are mutually perpendicular, the order of the vortex wave plate is 1, and the fast axis direction of the vortex wave plate is the same as the polarization direction of the polarizer of the first transmitting end optical channel.
The polarization directions of the polarizers of the third transmitting end optical channel and the fourth transmitting end optical channel are mutually perpendicular, the order of the vortex wave plate is 2, and the fast axis direction of the vortex wave plate is the same as the polarization direction of the polarizer of the third transmitting end optical channel.
According to any of the foregoing embodiments of the present application, the signal receiving terminal includes a receiving module, a second beam splitting module, a demodulating module and an information decoding module,
the receiving module is used for receiving the single-beam transmitting end signal beam from the beam combining module,
the second beam splitting module is used for splitting the transmitting end signal beam into multiple receiving end signal beams, each receiving end signal beam corresponds to one receiving end optical channel, the receiving end optical channels correspond to the transmitting end optical channels one by one,
the demodulation module is used for respectively converting each path of signal beam at the receiving end into multi-path polarized beams carrying signals, the sources of the signals carried by each path of polarized beams are different,
the information decoding module is used for receiving the multi-path polarized light beam and decoding the multi-path polarized light beam to obtain an original loading signal.
According to any of the foregoing embodiments of the present application, the demodulation module includes a vortex wave plate and a polarizing plate disposed along a propagation direction of a receiving-end signal beam of each receiving-end optical channel, and a combination of a polarization direction of the polarizing plate of each receiving-end optical channel and an order and a fast axis direction of the vortex wave plate is the same as a combination of a polarization direction of the polarizing plate of a corresponding transmitting-end optical channel and an order and a fast axis direction of the vortex wave plate.
According to any of the preceding embodiments of the present application, the first beam splitting module comprises a multiplexer for splitting the laser beam into multiple beams.
According to any of the preceding embodiments of the present application, the information loading module comprises an electro-optical intensity modulator arranged along the propagation direction of each beam for receiving the beam and loading the signal.
According to any of the foregoing embodiments of the present application, the light source module and the first beam splitting module, and the first beam splitting module and each of the optoelectronic intensity modulators are connected by optical fibers,
the signal transmitting end further comprises a space optical switching module, the space optical switching module comprises optical fiber collimators arranged along the propagation direction of the signal beams of each transmitting end, each photoelectric intensity modulator is connected with the corresponding optical fiber collimator through optical fibers, and each optical fiber collimator is used for converting optical fiber transmission optical signals into a space transmission mode.
According to any of the embodiments described above, the transmitting-end signal beams of the first transmitting-end optical channel and the second transmitting-end optical channel are transmitted to the vortex wave plate with the order of 1 through the first reflecting mirror after passing through the corresponding polarizing plates; or (b)
And transmitting the signal beams of the transmitting ends of the third transmitting end optical channel and the fourth transmitting end optical channel to the vortex wave plate with the order of 2 through the second reflecting mirror after passing through the corresponding polaroids.
According to any of the foregoing embodiments of the present application, the light-entering side of the polarizer of the second emission-side optical channel is provided with a third mirror; or (b)
The light incident side of the polarizer of the fourth transmitting-end optical channel is provided with a fourth reflecting mirror.
According to any of the foregoing embodiments of the present application, the beam combining module includes a spatial beam combiner, where the spatial beam combiner is configured to converge each column vector beam to form a single-beam transmitting-end signal beam, and send the single-beam transmitting-end signal beam to the signal receiving end.
According to any of the foregoing embodiments of the present application, the receiving module includes a narrow-band pass filter, and the narrow-band pass filter is configured to receive the single-beam transmitting-end signal beam from the beam combining module and filter noise in the single-beam transmitting-end signal beam.
According to any of the foregoing embodiments of the present application, the second beam splitting module includes a first beam splitter disposed on the light emitting side of the narrow band-pass filter, a second beam splitter disposed on the first light emitting side of the first beam splitter, a fifth mirror disposed on the second light emitting side of the first beam splitter, and a third beam splitter disposed on the light emitting side of the fifth mirror.
According to any of the embodiments described above, a spatial optical coupler is disposed on the light-emitting side of each receiving-end optical channel, and the spatial optical coupler is used for accessing an optical fiber connected to the information decoding module.
According to any of the foregoing embodiments of the present application, the information decoding module includes a photodetector and a signal decoder, each spatial light coupler is connected to one photodetector through an optical fiber, and all the photodetectors are connected to the signal decoder.
In the space optical communication system of the embodiment of the application, after the signal beams of the transmitting ends of different paths are modulated into different column vector beams, different optical elements can be arranged at the signal receiving end according to different polarization distribution due to different polarization distribution of the column vector beams, and other signals are filtered, so that the transmission of multipath signals can be realized. And the crosstalk between different column vector beams is small, so that the signal is not excessively disturbed. Therefore, by loading signals into different column vector beams for transmission, the information capacity of space communication can be improved, and crosstalk between signals can be reduced.
Drawings
Fig. 1 is a schematic structural diagram of a spatial optical communication system according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a spatial optical communication system according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a spatial optical communication system according to an embodiment of the present application;
fig. 4 is a schematic structural diagram of a spatial optical communication system according to an embodiment of the present application;
FIG. 5 is a schematic diagram of the generation of a vector light field with different columns;
fig. 6 is a schematic structural diagram of a spatial optical communication system according to an embodiment of the present application;
fig. 7 is a schematic structural diagram of a spatial optical communication system according to an embodiment of the present application.
Detailed Description
Features and exemplary embodiments of various aspects of the present application are described in detail below to make the objects, technical solutions and advantages of the present application more apparent, and to further describe the present application in conjunction with the accompanying drawings and the detailed embodiments. It should be understood that the specific embodiments described herein are intended to be illustrative of the application and are not intended to be limiting. It will be apparent to one skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present application by showing examples of the present application.
Referring to fig. 1 to 3, a spatial optical communication system 100 disclosed in an embodiment of the present application includes a signal transmitting end 1 and a signal receiving end 2, where information is transferred between the signal transmitting end 1 and the signal receiving end 2 through vacuum or atmosphere; the signal transmitting end 1 includes a light source module 11, a first beam splitting module 12, an information loading module 13 (the information loading module 13 of which only one transmitting-end optical channel is indicated by a reference numeral in fig. 2), a column vector beam generating module 14 (the column vector beam generating module 14 of which only one transmitting-end optical channel is indicated by a reference numeral in fig. 2), and a beam combining module 15.
The light source module 11 is used to generate a laser beam, for example, the light source module 11 may be used to emit a laser beam of 1550 nm.
The first beam splitting module 12 is used for splitting the laser beam into multiple beams; in some embodiments, the first beam splitting module 12 includes a multiplexer, for example, a 1*4 multiplexer may be employed to split the laser beam into four equal energy beams.
The information loading module 13 is configured to load signals for each path of light beams, so as to obtain multiple paths of emission end signal beams each carrying a signal, where each path of emission end signal beam corresponds to one path of emission end optical channel, and the signals carried by each path of emission end signal beam may be the same or different; in some embodiments, the information loading module 13 includes a plurality of light intensity modulators, each light beam split by the multiplexer corresponds to one light intensity modulator, the light intensity modulator is used for receiving the light beam, the signal to be loaded is loaded through the light intensity modulator, and the signal beam of the transmitting end carrying the signal is output from the output end of the light intensity modulator.
The column vector beam generating module 14 is configured to convert each path of signal beam at the transmitting end into different column vector beams; taking four transmitting-end signal beams as an example, the column vector beam generating module 14 can adjust the polarization state of each transmitting-end signal beam, modulate each transmitting-end signal beam into a column vector beam, and the polarization state distribution of each column vector beam is different.
The beam combining module 15 is configured to combine the vector beams of each column to form a single-beam transmitting-end signal beam, and send the single-beam transmitting-end signal beam to the signal receiving end 2. Each path of column vector light beam is converged to the beam combination module 15 to form a single-beam transmitting end signal light beam, and the single-beam transmitting end signal light beam is transmitted to the signal receiving end 2 through the beam combination module 15. In some embodiments, the beam combining module 15 includes a spatial beam combiner, and each column vector beam is converged to the spatial beam combiner to form a single-beam transmitting-end signal beam, and the single-beam transmitting-end signal beam propagates to the signal receiving end 2 through atmospheric vacuum or atmosphere.
It can be understood that after the signal beams of the transmitting end in different paths are modulated into different column vector beams, the signal receiving end 2 can select the target signal by arranging different optical elements according to different polarization distribution due to different polarization distribution of the column vector beams, and filter other signals, so that the transmission of multiple signals can be realized. And the crosstalk between different column vector beams is small, so that the signal is not excessively disturbed. Therefore, by loading signals into different column vector beams for transmission, the information capacity of space communication can be improved, and crosstalk between signals can be reduced.
Referring to fig. 3, in some embodiments, the post-vector light beam generating module 14 includes a polarizer 141 and a vortex wave plate 142 (reference numerals in the drawing only show the polarizer 141 and the vortex wave plate 142 in one path of the emission-side optical channel) disposed along the propagation direction of the emission-side signal light beam of each path of the emission-side optical channel, and the emission-side signal light beam is modulated by the polarizer 141 and the vortex wave plate 142 after being output from the information loading module 13, and is converted into the post-vector light beam; referring to fig. 4, taking four-way transmitting-end signal light beams and four-way transmitting-end optical channels as examples, that is, the transmitting-end optical channels include a first transmitting-end optical channel G1, a second transmitting-end optical channel G2, a third transmitting-end optical channel G3 and a fourth transmitting-end optical channel G4, wherein:
the polarization direction of the polaroid arranged in the first transmitting end optical channel G1 is 0 DEG, the order of the vortex wave plate arranged in the first transmitting end optical channel G1 is 1, and the included angle between the fast axis direction of the vortex wave plate and the polarization direction of the polaroid is 0 DEG; after the transmitting end signal beam of the first transmitting end optical channel G1 is modulated by a polaroid and a vortex wave plate, a column vector light field with an initial phase of 0 DEG and an order of 1 is formed;
the polarization direction of the polaroid arranged in the second transmitting end optical channel G2 is 90 degrees, the order of the vortex wave plate arranged in the second transmitting end optical channel G2 is 1, and the included angle between the fast axis direction of the vortex wave plate and the polarization direction of the polaroid is 90 degrees; after the transmitting end signal beam of the second transmitting end optical channel G2 is modulated by a polaroid and a vortex wave plate, a column vector light field with an initial phase of 90 degrees and an order of 1 is formed;
the polarization direction of the polaroid arranged in the third transmitting end optical channel G3 is 0 degrees, the order of the vortex wave plate arranged in the third transmitting end optical channel G3 is 2, and the included angle between the fast axis direction of the vortex wave plate and the polarization direction of the polaroid is 0 degrees; after the transmitting end signal beam of the third transmitting end optical channel G3 is modulated by the polaroid and the vortex wave plate, a column vector light field with an initial phase of 0 DEG and an order of 2 is formed;
the polarization direction of the polaroid arranged in the fourth transmitting end optical channel G4 is 90 degrees, the order of the vortex wave plate arranged in the fourth transmitting end optical channel G4 is 2, and the included angle between the fast axis direction of the vortex wave plate and the polarization direction of the polaroid is 90 degrees; the transmitting end signal beam of the fourth transmitting end optical channel G4 is modulated by the polaroid and the vortex wave plate to form a column vector light field with an initial phase of 90 degrees and an order of 2.
It is understood that the first emission-end optical channel G1 and the second emission-end optical channel G2 may share a same vortex wave plate (first vortex wave plate 141), the third emission-end optical channel and the fourth emission-end optical channel may share a same vortex wave plate (second vortex wave plate 142), and the orders of the first vortex wave plate 141 and the second vortex wave plate 142 are different.
As shown in the above example, it is preferable that the polarization directions of the polarizers in the first and second emission-end optical channels G1 and G2 are perpendicular to each other, and the polarization directions of the polarizers in the third and fourth emission-end optical channels G3 and G4 are perpendicular to each other. It will be appreciated that cross-talk between signals can be avoided by using orthogonally polarized light as the information carrier.
As can be seen from the above examples, the number of the optical channels at the transmitting end is preferably an even number, and the two optical channels at the transmitting end are used as a group to share one vortex wave plate, and the orders of the vortex wave plates adopted by different groups are different; the polarization directions of the polarizers in the same group of the emission-end optical channels are perpendicular to each other. Therefore, the polarization directions of the two paths of column vector light beams output by the same group of transmitting end optical channels are mutually perpendicular, and crosstalk of signals transmitted by the same group of transmitting end optical channels can be avoided. And the column vector beams output by different groups have different orders, so that crosstalk among the column vector beams with different orders cannot cause excessive interference to signals.
In some embodiments, a 1*6 multiplexer may be used to split the laser beam into six equal energy beams, each of which is loaded with a signal; correspondingly, six paths of optical channels at the transmitting end are arranged, two paths of optical channels at the transmitting end are used as a group to share one vortex wave plate, and the orders of the three vortex wave plates are 1 order, 2 order and 3 order respectively.
In some embodiments, the signal receiving end 2 includes a receiving module 21, a second beam splitting module 22, a demodulating module 23, and an information decoding module 24.
The receiving module 21 is configured to receive the single-beam transmitting-end signal beam from the beam combining module 15, for example, the receiving module 21 may include a narrow-band pass filter configured to receive the single-beam transmitting-end signal beam from the beam combining module 15 and filter noise in the single-beam transmitting-end signal beam.
The second beam splitting module 22 is configured to split the transmitting-end signal beam into multiple receiving-end signal beams, where each receiving-end signal beam corresponds to one receiving-end optical channel, and the receiving-end optical channels correspond to the transmitting-end optical channels one by one, i.e. the number of the receiving-end optical channels is the same as the number of the transmitting-end optical channels, and finally, the purpose is to demodulate a signal through one receiving-end optical channel.
The demodulation module 23 is configured to convert each path of signal beam at the receiving end into a multi-path polarized beam carrying signals, where the sources of signals carried by each path of polarized beam are different; taking the example of four receiving end signal beams, the demodulation module 23 can convert the four receiving end signal beams into linearly polarized light beams, and the four linearly polarized light beams carry corresponding loading signals.
The information decoding module 24 is configured to receive the multi-path polarized light beam and decode the multi-path polarized light beam to obtain the original loading signal.
In some embodiments, demodulation module 23 includes a vortex plate 231 and a polarizer 232 (only vortex plate 231 and polarizer 232 in one receiving-end optical channel are shown in fig. 3 by reference numerals) disposed along the propagation direction of the receiving-end signal beam of each receiving-end optical channel, and the combination of the polarization direction of polarizer 232 and the order and fast axis direction of vortex plate 231 of each receiving-end optical channel is the same as the combination of the polarization direction of polarizer 141 and the order of vortex plate 142 of the corresponding transmitting-end optical channel. The signal beam at the receiving end is converted into linearly polarized light after passing through the vortex wave plate 231 and the polarizing plate 232 in sequence, and demodulation of the signal beam at the receiving end is completed. Taking four transmitting-end signal beams, four transmitting-end optical channels and four receiving-end optical channels as examples, namely, the transmitting-end optical channels comprise a first transmitting-end optical channel G1, a second transmitting-end optical channel G2, a third transmitting-end optical channel G3 and a fourth transmitting-end optical channel G4, and the receiving-end optical channels comprise a first receiving-end optical channel O1, a second receiving-end optical channel O2, a third receiving-end optical channel O3 and a fourth receiving-end optical channel O4, wherein:
the polarization direction of the polaroid arranged in the first receiving end optical channel O1 is 0 degree, the order of the vortex wave plate arranged in the first receiving end optical channel O1 is 1, and the included angle between the fast axis direction of the vortex wave plate and the polarization direction of the polaroid is 0 degree; the signal beam of the receiving end of the first receiving end optical channel O1 is demodulated by the vortex wave plate and the polaroid to form a 0-degree linearly polarized beam;
the polarization direction of the polaroid arranged in the second receiving end optical channel O2 is 90 degrees, the order of the vortex wave plate arranged in the second receiving end optical channel O2 is 1, and the included angle between the fast axis direction of the vortex wave plate and the polarization direction of the polaroid is 90 degrees; the signal beam of the receiving end of the second receiving end optical channel O2 is demodulated by the vortex wave plate and the polaroid to form a 90-degree linear polarized beam;
the polarization direction of the polaroid arranged in the third receiving end optical channel O3 is 0 DEG, the order of the vortex wave plate arranged in the third receiving end optical channel O3 is 2, and the included angle between the fast axis direction of the vortex wave plate and the polarization direction of the polaroid is 0 DEG; the signal beam of the receiving end of the third receiving end optical channel O3 is demodulated by the vortex wave plate and the polaroid to form a 0-degree linearly polarized beam;
the polarization direction of the polaroid arranged in the fourth receiving-end optical channel O4 is 90 degrees, the order of the vortex wave plate arranged in the fourth receiving-end optical channel O4 is 2, and the included angle between the fast axis direction of the vortex wave plate and the polarization direction of the polaroid is 90 degrees; the signal beam of the receiving end of the fourth receiving end optical channel O4 is demodulated by the vortex wave plate and the polaroid to form a 90-degree linear polarized beam.
According to the embodiment, vortex wave plates with different orders and polaroids with different polarization directions (or polarization angles) are arranged according to different polarization state distributions of signal beams at a receiving end so as to select signals.
The vortex wave plate used in the above embodiment has polarization-dependent optical characteristics, and can be used for generating vector polarized light beams according to the polarization states of incident light beams, so that TEM (transmission electron microscope) can be realized 00 The mode Gaussian beam is converted into a "hollow-bore" Laguerre-Gaussian (LG) intensity distribution. When the polarizing plate is used for changing the Gaussian beam output by the laser into the direction of 0-degree fast axis of which the polarization direction is parallel to the vortex wave plate, the output light field is a radial polarized beam, and if the polarization direction of the Gaussian beam is perpendicular to the direction of 0-degree fast axis of the vortex wave plate, the output light field mode is an angular vector light field. When linearly polarized light of any angle passes through the vortex wave plate, a generalized cylindrical vector light field can be generated.
The Jones matrix is utilized to represent the light field change, and the linear polarized light with horizontal linear polarization, vertical linear polarization and any angle respectively passes through the vortex wave plate to generate vector light field expression as follows:
When 0 ° and 90 ° linearly polarized light is used as incident light, the vortex wave plates of different orders produce four kinds of cylinder vector light fields as shown in fig. 5 (M in fig. 5 represents the order of the vortex wave plates).
After four paths of signals are loaded in four kinds of column vector light fields, as the polarization state distribution of the column vector light fields is different, the demodulation module 23 at the receiving end arranges the polaroids with different polarization directions according to the different polarization state distribution to select information in the signals and filter other information amounts, so that loading demodulation of the signals is completed.
It can be understood that in the optical path transmission process, because the same-order column vector optical field is in polarization orthogonal distribution, the crosstalk is smaller in the channel transmission, and the later polarization can be decomposed to restore different signals. The column vector optical field crosstalk of different orders does not cause excessive interference to the signal.
With continued reference to fig. 2, in some embodiments, the light source module 11 and the first beam splitting module 12, and the first beam splitting module 12 and the optical-electrical intensity modulators are connected by optical fibers, the signal transmitting end 1 further includes a spatial light switching module 16, the spatial light switching module 16 includes optical fiber collimators disposed along the propagation direction of the signal beam of each transmitting end, and the optical-electrical intensity modulators and the corresponding optical fiber collimators are connected by optical fibers, and the optical fiber transmission optical signals can be converted into a spatial transmission mode by using the optical fiber collimators.
In some embodiments, the transmitting-end signal beams of the first transmitting-end optical channel G1 and the second transmitting-end optical channel G2 pass through the corresponding polarizers and then are transmitted to the vortex wave plate with the order of 1 through the first reflector F1. The transmission surface of the first reflector F1 is plated with an antireflection film, and the reflection surface is plated with a reflection film, so that the energy loss of the signal beam at the transmitting end is reduced. Thus, the first emission-end optical channel G1 and the second emission-end optical channel G2 can share a first-order vortex wave plate.
In some embodiments, the emitter signal beams of the third emitter optical channel G3 and the fourth emitter optical channel G4 are transmitted to the vortex wave plate with the order of 2 through the second mirror F2 after passing through the corresponding polarizers. Similarly, the transmission surface of the second reflector F2 is plated with an antireflection film, and the reflection surface is plated with a reflection film, so that the energy loss of the signal beam at the transmitting end is reduced. Thus, the third emission-end optical channel G3 and the fourth emission-end optical channel G4 can share one second-order vortex wave plate.
In some embodiments, the light entrance side of the polarizer of the second emission-side optical channel G2 is provided with a third mirror F3; in this way, the optical path direction of the emission end signal beam can be changed by the third reflector F3, so that the emission end signal beam of the second emission end optical channel G2 is finally combined with the emission end signal beam of the first emission end optical channel G1 at the third reflector F3.
In some embodiments, the light entrance side of the polarizer of the fourth emission-side optical channel G4 is provided with a fourth mirror F4; in this way, the optical path direction of the emission end signal beam can be changed by the fourth reflector F4, so that the emission end signal beam of the fourth emission end optical channel G4 is finally combined with the emission end signal beam of the third emission end optical channel G3 at the fourth reflector F4.
Referring to fig. 6, in some embodiments, the second beam splitting module 22 includes a first beam splitter H1 disposed on the light emitting side of the narrow band-pass filter, a second beam splitter H2 disposed on the first light emitting side of the first beam splitter H1, a fifth reflecting mirror F5 disposed on the second light emitting side of the first beam splitter H1, and a third beam splitter H3 disposed on the light emitting side of the fifth reflecting mirror F5.
In some embodiments, a spatial optical coupler 25 is disposed on the light-emitting side of each receiving-end optical channel, and the spatial optical coupler 25 is used to access the optical fiber connected to the information decoding module 24.
In some embodiments, the information decoding module 24 includes photodetectors 241 and signal decoders 242 (reference numerals in fig. 6 only show photodetectors in one receiving-end optical channel), each spatial light coupler is connected to one photodetector 241 by an optical fiber, and all photodetectors 241 are connected to the signal decoder 242.
The spatial light communication system 100 of the embodiment of the application has a simple structure, can utilize one set of system to complete the generation of at least four paths of vector light fields, and reduces the use cost. The demodulation module 23 of the signal receiving end 2 utilizes the principle of optical path mutual dissimilarity to realize the restoration and selection of the polarization state in the vector light field, and excessive complicated operations are not needed.
Examples
Referring to fig. 7, a spatial optical communication system 100 includes a signal transmitting end 1 and a signal receiving end 2.
The signal emitting end 1 includes a laser 111, a 1*4 multiplexer 121, a first source 1311, a second source 1312, a third source 1313, a fourth source 1314, a first photoemission intensity modulator 1321, a second photoemission intensity modulator 1322, a third photoemission intensity modulator 1323, a fourth photoemission intensity modulator 1324, a first fiber collimator 161, a second fiber collimator 162, a third fiber collimator 163, a fourth fiber collimator 164, a fourth mirror F4 (total reflection mirror), a second mirror F2 (reflection mirror), a third mirror (total reflection mirror), a first mirror (reflection mirror), a first polarizer 1411 (film polarizer), a second polarizer 1412 (film polarizer), a third polarizer 1413 (film polarizer), a fourth polarizer 1414 (film polarizer), a first vortex 1421 (first vortex wave plate), a second vortex 1422 (second vortex wave plate), and a spatial light combining device 151, which can emit 1550 nm laser beams.
The signal receiving demodulation end includes a narrow bandpass filter 211, a first beam splitter H1 (50:50 optical beam splitting cube), a fifth reflecting mirror F5 (total reflecting mirror), a second beam splitter H2 (50:50 optical beam splitting cube), a third beam splitter H3 (50:50 optical beam splitting cube), a third vortex plate 2311 (first order vortex plate), a fourth vortex plate 2312 (first order vortex plate), a fifth vortex plate 2313 (second order vortex plate), a sixth vortex plate 2314 (second order vortex plate), a fifth polarizer 2321 (film polarizer), a sixth polarizer 2322 (film polarizer), a seventh polarizer 2323 (film polarizer), an eighth polarizer 2324 (film polarizer), a first spatial optical coupler 251, a second spatial optical coupler 252, a third spatial optical coupler 253, a fourth spatial optical coupler 254, a first photodetector 2411, a second photodetector 2412, a third photodetector 2413, a fourth photodetector 2414, and a signal decoder 242.
System operation principle: the laser 111 produces a stable 1550 nm laser beam which is split into 4 equal energy beams by the 1*4 multiplexer 121. The four beams are respectively carried with different signals and formed by the optical paths at the rear end
Wherein m is the order of the column vector beam, < >>
Is the initial phase of the column vector beam and is finally transmitted in a combined beam.
Four column vector light fields are loaded with four paths of signals and transmitted to the demodulation module 23 end in a space channel, filtering of signal noise is completed through the narrow-band filter 211, the four paths of signals are transmitted to the first beam splitter H1 and the fifth reflecting mirror F5 to divide the incident light signals into two paths of energy equally, the second beam splitter H2 and the third beam splitter H3 are used for splitting the signals again after the two paths of signals are divided into four paths of identical signal lights finally.
The four-path optical signals are subjected to mode inverse solution by using a first-order vortex wave plate (a third vortex wave plate 2311, a fourth vortex wave plate 2312) and a second-order vortex wave plate (a fifth vortex wave plate 2313 and a sixth vortex wave plate 2314), and then are matched with 90-degree polarizers (a sixth polarizer 2322 and an eighth polarizer 2324) or 0-degree polarizers (a fifth polarizer 2321 and a seventh polarizer 2323) to select the optical signals so as to obtain initial signals, and then the signals are subjected to photoelectric conversion by using a space optical coupler and a photoelectric detector, and finally are input to a signal decoder 242 to complete communication.
Claims (16)
1. The space optical communication system comprises a signal transmitting end and a signal receiving end, and is characterized in that: the signal transmitting end comprises a light source module, a first beam splitting module, an information loading module, a column vector beam generating module and a beam combining module,
the light source module is used for generating a laser beam,
the first beam splitting module is used for splitting the laser beam into multiple paths of beams,
the information loading module is used for loading signals for each path of light beam to obtain a plurality of paths of signal light beams of the transmitting end carrying the signals, each path of signal light beam of the transmitting end corresponds to one path of optical channel of the transmitting end,
the column vector beam generating module is used for respectively converting each path of signal beam at the transmitting end into different column vector beams,
the beam combination module is used for converging each path of column vector light beams to form a single-beam transmitting end signal light beam and transmitting the single-beam transmitting end signal light beam to the signal receiving end.
2. The spatial light communication system according to claim 1, wherein: the column vector light beam generating module comprises polaroids and vortex wave plates which are arranged along the propagation direction of the transmitting end signal light beams of each path of transmitting end optical channel, and different combinations of the polarization directions of the polaroids of different transmitting end optical channels and the order and the fast axis directions of the vortex wave plates correspond to different column vector light beams.
3. The spatial light communication system according to claim 2, wherein: the number of the optical channels of the transmitting end is even, and the optical channels of the two transmitting ends are a group;
the polarization directions of the polarizers of the optical channels at different emission ends in the same group are mutually perpendicular, vortex wave plates are shared among the optical channels at different emission ends in the same group, and the fast axis direction of the vortex wave plates is the same as the polarization direction of the polarizer of one of the optical channels at the emission end;
the order of the vortex wave plates is different between different groups.
4. A spatial optical communication system according to claim 3, characterized in that: the transmitting end optical channel comprises a first transmitting end optical channel, a second transmitting end optical channel, a third transmitting end optical channel and a fourth transmitting end optical channel,
the polarization directions of the polarizers of the first transmitting end optical channel and the second transmitting end optical channel are mutually perpendicular, the order of the vortex wave plate is 1, the fast axis direction of the vortex wave plate is the same as the polarization direction of the polarizer of the first transmitting end optical channel,
the polarization directions of the polarizers of the third transmitting end optical channel and the fourth transmitting end optical channel are mutually perpendicular, the order of the vortex wave plate is 2, and the fast axis direction of the vortex wave plate is the same as the polarization direction of the polarizer of the third transmitting end optical channel.
5. The spatial light communication system according to any one of claims 1 to 4, wherein: the signal receiving end comprises a receiving module, a second beam splitting module, a demodulation module and an information decoding module,
the receiving module is used for receiving the single-beam transmitting end signal beam from the beam combining module,
the second beam splitting module is used for splitting the signal beam of the transmitting end into multiple signal beams of the receiving end, each signal beam of the receiving end corresponds to one optical channel of the receiving end, the optical channels of the receiving end correspond to the optical channels of the transmitting end one by one,
the demodulation module is used for respectively converting each path of signal beam at the receiving end into multi-path polarized beams carrying signals, the sources of the signals carried by the polarized beams of each path are different,
the information decoding module is used for receiving the multi-path polarized light beam and decoding the multi-path polarized light beam to obtain an original loading signal.
6. The spatial light communication system according to claim 5, wherein: the demodulation module comprises vortex wave plates and polaroids, wherein the vortex wave plates and the polaroids are arranged along the propagation direction of receiving end signal beams of all paths of receiving end optical channels, and the combination of the polarization direction of the polaroids of all paths of receiving end optical channels and the order and the fast axis direction of the vortex wave plates is the same as the combination of the polarization direction of the polaroids of corresponding transmitting end optical channels and the order and the fast axis direction of the vortex wave plates.
7. The spatial light communication system according to claim 1, wherein: the first beam splitting module includes a multiplexer for splitting the laser beam into multiple beams.
8. The spatial light communication system according to claim 7, wherein: the information loading module comprises an optoelectronic intensity modulator arranged along the propagation direction of each beam for receiving the beam and loading the signal.
9. The spatial light communication system according to claim 8, wherein: the light source module is connected with the first beam splitting module and the first beam splitting module is connected with each photoelectric intensity modulator through optical fibers,
the signal transmitting end further comprises a space optical switching module, the space optical switching module comprises optical fiber collimators arranged along the propagation direction of the signal beams of each transmitting end, each photoelectric intensity modulator is connected with the corresponding optical fiber collimator through an optical fiber, and each optical fiber collimator is used for converting an optical fiber transmission optical signal into a space transmission mode.
10. The spatial light communication system according to claim 4, wherein: transmitting end signal beams of the first transmitting end optical channel and the second transmitting end optical channel pass through the corresponding polaroids and then are transmitted to a vortex wave plate with the order of 1 through a first reflector; or (b)
And the signal beams of the transmitting ends of the third transmitting end optical channel and the fourth transmitting end optical channel are transmitted to the vortex wave plate with the order of 2 through the second reflecting mirror after passing through the corresponding polaroids.
11. The spatial light communication system according to claim 10, wherein: a third reflector is arranged on the light entering side of the polaroid of the second transmitting end optical channel; or (b)
And a fourth reflector is arranged on the light incident side of the polaroid of the fourth transmitting end optical channel.
12. The spatial light communication system according to claim 1, wherein: the beam combining module comprises a space beam combiner, and the space beam combiner is used for converging each path of column vector light beams to form a single-beam transmitting end signal light beam and transmitting the single-beam transmitting end signal light beam to the signal receiving end.
13. The spatial light communication system according to claim 5, wherein: the receiving module comprises a narrow-band pass filter, and the narrow-band pass filter is used for receiving the single-beam transmitting end signal beam from the beam combining module and filtering noise in the single-beam transmitting end signal beam.
14. The spatial light communication system according to claim 13, wherein: the second beam splitting module comprises a first beam splitter arranged on the light emitting side of the narrow-band pass filter, a second beam splitter arranged on the first light emitting side of the first beam splitter, a fifth reflecting mirror arranged on the second light emitting side of the first beam splitter, and a third beam splitter arranged on the light emitting side of the fifth reflecting mirror.
15. The spatial light communication system according to claim 5, wherein: and a space optical coupler is arranged on the light-emitting side of each path of receiving end optical channel, and the space optical coupler is used for accessing an optical fiber connected with the information decoding module.
16. The spatial light communication system according to claim 15, wherein: the information decoding module comprises photoelectric detectors and signal decoders, each space optical coupler is connected with one photoelectric detector through an optical fiber, and all the photoelectric detectors are connected with the signal decoders.
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