Optical millimeter wave receiving end, transmitting end, system, demodulation method and modulation method

Abstract

The embodiment of the present application relates to the field of optical communication technology, in particular to an optical millimeter wave receiving end, a transmitting end, a system, a demodulation method and a modulation method. The optical millimeter wave receiving end comprises: a first coupler, used for dividing the received optical signal into a first optical signal, a second optical signal and a third optical signal; a demodulation module, used for rotating the polarization state of the local oscillator light in the third optical signal, dividing the rotated third optical signal into a fourth optical signal and a fifth optical signal, and obtaining a first radio frequency signal, a second radio frequency signal, a third radio frequency signal and a fourth radio frequency signal by filtering out the lower sideband of the first optical signal, the upper sideband of the second optical signal, the lower sideband of the fourth optical signal and the upper sideband of the fifth optical signal respectively. The optical millimeter wave receiving end provided by the embodiment of the present application can effectively reduce the complexity of the optical millimeter wave wireless system, thereby reducing the investment cost of the optical millimeter wave wireless system.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, and in particular to an optical millimeter-wave receiver, transmitter, system, demodulation method, and modulation method. Background Technology

[0002] With the gradual popularization of 5G (5th Generation Mobile Communication Technology) and the rapid development of various Internet services, 5G technology is gradually moving towards millimeter waves. Optical millimeter wave wireless systems, namely coherent optical communication technology, are attracting more and more research interest. Coherent optical communication technology suffers from problems such as frequency offset and phase noise caused by the inconsistency in phase and frequency between the local oscillator light and the signal light. Random birefringence of optical fiber can cause aliasing of the two orthogonal polarization states during transmission. Dispersion in optical fiber can lead to intersymbol interference. These problems can all result in poor quality of coherent optical communication systems. Related technologies generally use digital signal processing methods to recover the signal, or configure a polarization controller or add a laser at the receiving end to correct the coherent optical communication system.

[0003] However, using digital signal processing modules to recover signals requires the introduction of a large number of digital signal processing modules, and configuring polarization controllers and adding lasers at the receiving end also introduces a large number of redundant modules. These modules make optical millimeter-wave wireless systems too complex and costly. Summary of the Invention

[0004] The main objective of this application is to propose an optical millimeter-wave receiver, transmitter, system, demodulation method, and modulation method, which can effectively reduce the complexity of the optical millimeter-wave wireless system and thus reduce the investment cost of the optical millimeter-wave wireless system.

[0005] To achieve the above objectives, this application provides an optical millimeter-wave receiver, comprising: a first coupler for splitting a received optical signal into a first optical signal, a second optical signal, and a third optical signal; wherein each optical signal includes a local oscillator light and a signal light, the signal light including a first polarized signal light and a second polarized signal light, the upper sideband of the first polarized signal light being modulated with a first radio frequency (RF) signal, the lower sideband of the first polarized signal light being modulated with a second RF signal, the upper sideband of the second polarized signal light being modulated with a third RF signal, and the lower sideband of the second polarized signal light being modulated with a fourth RF signal, the polarization state of the first polarized signal light being correlated with that of the second polarized signal light. The polarization states of the signal light are orthogonal, and the polarization state of the local oscillator light is the same as that of the first polarized signal light. The demodulation module is used to rotate the polarization state of the local oscillator light in the third optical signal, and then divide the rotated third optical signal into a fourth optical signal and a fifth optical signal. The first radio frequency signal, the second radio frequency signal, the third radio frequency signal, and the fourth radio frequency signal are obtained by filtering out the lower sideband of the first optical signal, the upper sideband of the second optical signal, the lower sideband of the fourth optical signal, and the upper sideband of the fifth optical signal, respectively. The polarization state of the rotated local oscillator light is the same as that of the second polarized signal light.

[0006] To achieve the above objectives, this application also provides an optical millimeter-wave transmitter, comprising: a laser, a third coupler, a modulator, a polarization controller, and a fourth coupler; the laser is connected to the third coupler, the third coupler is connected to the modulator and the polarization controller, and the modulator and the polarization controller are both connected to the fourth coupler; the laser is used to emit laser light; the third coupler is used to split the laser light emitted by the laser into a first path of light carrying a modulation signal and a second path of light serving as a local oscillator; the modulator is used to modulate the first path of radio frequency signal onto the upper sideband of a first polarization state optical carrier of the first path of light, and to adjust the second path of radio frequency signal onto the first path of light. The lower sideband of the first polarization state optical carrier is used to obtain the first polarization signal light carrying the modulation signal; the third radio frequency signal is adjusted to the upper sideband of the second polarization state optical carrier of the first light, and the fourth radio frequency signal is adjusted to the lower sideband of the second polarization state optical carrier of the first light to obtain the second polarization signal light carrying the modulation signal; wherein, the polarization state of the first polarization signal light is orthogonal to the polarization state of the second polarization signal light; the polarization controller is used to modulate the polarization state of the local oscillator light to be the same as the polarization state of the first polarization signal light; the fourth coupler is used to combine the first polarization signal light, the second polarization signal light and the local oscillator light and input them into the optical fiber link for transmission.

[0007] To achieve the above objectives, embodiments of this application also provide an optical millimeter-wave wireless system, including the aforementioned optical millimeter-wave receiver and optical millimeter-wave transmitter.

[0008] To achieve the above objectives, this application also provides an optical millimeter-wave demodulation method, the method comprising: dividing a received optical signal into a first optical signal, a second optical signal, and a third optical signal; wherein each optical signal includes a local oscillator light and a signal light, the signal light including a first polarized signal light and a second polarized signal light, the upper sideband of the first polarized signal light being modulated with a first radio frequency (RF) signal, the lower sideband of the first polarized signal light being modulated with a second RF signal, the upper sideband of the second polarized signal light being modulated with a third RF signal, and the lower sideband of the second polarized signal light being modulated with a fourth RF signal, the polarization state of the first polarized signal light being the same as that of the second polarized signal light. The polarization states of the two polarized signal lights are orthogonal, and the polarization state of the local oscillator light is the same as that of the first polarized signal light. The polarization state of the local oscillator light in the third optical signal is rotated, and the rotated third optical signal is divided into a fourth optical signal and a fifth optical signal. The polarization state of the rotated local oscillator light is the same as that of the second polarized signal light. The lower sideband of the first optical signal, the upper sideband of the second optical signal, the lower sideband of the fourth optical signal, and the upper sideband of the fifth optical signal are filtered out respectively to obtain the first radio frequency signal, the second radio frequency signal, the third radio frequency signal, and the fourth radio frequency signal.

[0009] To achieve the above objectives, this application also provides an optical millimeter-wave modulation method, the method comprising: dividing a laser emitted by a laser into a first optical path for carrying a modulation signal and a second optical path as a local oscillator; modulating the first radio frequency signal onto the upper sideband of a first polarization state optical carrier of the first optical path, and modulating the second radio frequency signal onto the lower sideband of the first polarization state optical carrier of the first optical path, to obtain a first polarization signal light carrying the modulation signal; modulating a third radio frequency signal onto the upper sideband of a second polarization state optical carrier of the first optical path, and modulating a fourth radio frequency signal onto the lower sideband of the second polarization state optical carrier of the first optical path, to obtain a second polarization signal light carrying the modulation signal; adjusting the polarization state of the local oscillator light to be the same as the polarization state of the first polarization signal light; and combining the first polarization signal light, the second polarization signal light, and the local oscillator light into a single beam and inputting it into an optical fiber link for transmission.

[0010] Compared to related technologies that use digital signal processing to recover signals or to modify coherent optical communication systems by configuring polarization controllers or adding lasers at the receiver, the embodiments of this application do not require any digital signal processing modules at the receiver, nor do they require configuring polarization controllers or adding lasers at the receiver. Signal separation can be achieved using only existing hardware, eliminating problems such as frequency offset and phase noise, polarization state aliasing, and inter-symbol interference. This effectively reduces the complexity of the optical millimeter-wave wireless system, thereby reducing the investment cost of the optical millimeter-wave wireless system. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of an optical millimeter-wave receiver according to an embodiment of this application. Figure 1 ;

[0012] Figure 2 This is a schematic diagram of the structure of an optical millimeter-wave receiver according to an embodiment of this application. Figure 2 ;

[0013] Figure 3 This is a schematic diagram of the structure of an optical millimeter-wave receiver according to an embodiment of this application. Figure 3 ;

[0014] Figure 4 This is a schematic diagram of the structure of an optical millimeter-wave receiver according to an embodiment of this application. Figure 4 ;

[0015] Figure 5 This is a schematic diagram of the structure of an optical millimeter-wave transmitter according to another embodiment of this application;

[0016] Figure 6 This is a schematic diagram of the structure of an optical millimeter-wave wireless system according to another embodiment of this application.

[0017] Figure 7 This is a flowchart of an optical millimeter-wave demodulation method according to another embodiment of this application;

[0018] Figure 8 This is a flowchart provided in another embodiment of the present application, which shows how to obtain a first radio frequency signal, a second radio frequency signal, a third radio frequency signal, and a fourth radio frequency signal by respectively filtering out the lower sideband of the first optical signal, the upper sideband of the second optical signal, the lower sideband of the fourth optical signal, and the upper sideband of the fifth optical signal.

[0019] Figure 9 This is a flowchart of an optical millimeter-wave modulation method according to another embodiment of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this application to help readers better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0021] One embodiment of this application relates to an optical millimeter-wave receiver. The implementation details of the optical millimeter-wave receiver of this embodiment are described below. The following details are provided for ease of understanding and are not essential for implementing this solution.

[0022] A schematic diagram of the optical millimeter-wave receiver in this embodiment can be seen as follows: Figure 1 As shown, it includes: a first coupler 11 and a demodulation module 12, with the first coupler 11 connected to the demodulation module 12.

[0023] The first coupler 11 is used to split the received optical signal into a first optical signal, a second optical signal, and a third optical signal.

[0024] Specifically, each of the three optical signals—the first optical signal, the second optical signal, and the third optical signal—includes a local oscillator light and a signal light. The signal light includes a first polarized signal light and a second polarized signal light. The upper sideband of the first polarized signal light is modulated with a first radio frequency (RF) signal, and the lower sideband of the first polarized signal light is modulated with a second RF signal. The upper sideband of the second polarized signal light is modulated with a third RF signal, and the lower sideband of the second polarized signal light is modulated with a fourth RF signal. The polarization state of the first polarized signal light is orthogonal to the polarization state of the second polarized signal light, and the polarization state of the local oscillator light is the same as the polarization state of the first polarized signal light.

[0025] In a specific implementation, the transmitter modulates four independent baseband signals into one optical signal. The first coupler 11 can receive the optical signal sent by the transmitter in real time. After receiving the optical signal sent by the transmitter, the first coupler 11 can divide the received optical signal into a first optical signal, a second optical signal, and a third optical signal. This splitting of the optical signal makes it easier to perform subsequent demodulation.

[0026] In one example, the first coupler 11 divides the received optical signal into a first optical signal, a second optical signal, and a third optical signal, which can multiplex the received optical signal and output the first optical signal, the second optical signal, and the third optical signal. These three optical signals are the same as the optical signal received by the first coupler 11.

[0027] The demodulation module 12 is used to rotate the polarization state of the local oscillator light in the third optical signal, and then divide the rotated third optical signal into a fourth optical signal and a fifth optical signal. The first, second, third and fourth radio frequency signals are obtained by filtering out the lower sideband of the first optical signal, the upper sideband of the second optical signal, the lower sideband of the fourth optical signal and the upper sideband of the fifth optical signal, respectively.

[0028] Specifically, the polarization state of the rotated local oscillator light is the same as that of the second polarized signal light.

[0029] In its specific implementation, after receiving the first, second, and third signal lights transmitted from the first coupler 11, the demodulation module 12 directly filters out the lower sideband of the first signal light and the upper sideband of the second signal light. After rotating the polarization state of the local oscillator light in the third signal light by 90°, it splits the rotated third optical signal into a fourth and fifth optical signal. The polarization state of the rotated local oscillator light is the same as that of the second polarized signal light. Then, the lower sideband of the fourth optical signal and the upper sideband of the fifth optical signal are filtered out. The first radio frequency (RF) signal is obtained based on the retained upper sideband of the first signal light, the second RF signal is obtained based on the lower sideband of the second signal light, the third RF signal is obtained based on the upper sideband of the fourth optical signal, and the fourth RF signal is obtained based on the lower sideband of the fifth optical signal. This embodiment of the application does not require any digital signal processing module; the separation of the four signals can be achieved using only existing hardware, effectively reducing the complexity and cost of the optical millimeter-wave wireless system.

[0030] Compared to related technologies that use digital signal processing methods to recover signals or to modify coherent optical communication systems by configuring polarization controllers or adding lasers at the receiving end, this embodiment of the application eliminates the need for any digital signal processing module at the receiving end, as well as the need for configuring polarization controllers or adding lasers. It achieves signal separation using only existing hardware, thereby eliminating problems such as frequency offset and phase noise, polarization state aliasing, and inter-symbol interference. This effectively reduces the complexity of optical millimeter-wave wireless systems and thus lowers the investment cost of optical millimeter-wave wireless systems.

[0031] In one embodiment, the structural schematic diagram of the optical millimeter-wave receiver can be as follows: Figure 2As shown, the demodulation module 12 includes a rotating branch module 121, a first demodulation submodule 122, a second demodulation submodule 123, a third demodulation submodule 124, and a fourth demodulation submodule 125.

[0032] The first coupler 11 is connected to the rotary branch module 121, the first demodulation submodule 122 and the second demodulation submodule 123 of the demodulation module 12. The rotary branch module 121 is also connected to the third demodulation submodule 124 and the fourth adjustment submodule 125.

[0033] The rotating splitter module 121 is used to rotate the polarization state of the local oscillator light in the third optical signal, and then split the rotated third optical signal into a fourth optical signal and a fifth optical signal.

[0034] In the specific implementation, the polarization state of the local oscillator light in the third optical signal is rotated, and the rotated third optical signal is then split into a fourth and a fifth optical signal by the rotation splitting module 121. The first coupler 11 can input the split third optical signal into the rotation splitting module 121. The rotation splitting module 121 rotates the polarization state of the local oscillator light in the third optical signal by 90°, splitting the rotated third optical signal into a fourth and a fifth optical signal. The polarization state of the local oscillator light in the rotated third optical signal is the same as the polarization state of the second polarized signal light.

[0035] The first demodulation submodule 122 is used to filter out the lower sideband of the first optical signal and to generate the first radio frequency signal based on the local oscillator light and the first polarization signal light in the first optical signal after the lower sideband is filtered out.

[0036] The second demodulation submodule 123 is used to filter out the upper sideband of the second optical signal and to generate the second radio frequency signal based on the local oscillator light and the first polarization signal light in the second optical signal after the upper sideband is filtered out.

[0037] The third demodulation submodule 124 is used to filter out the lower sideband of the fourth optical signal and to generate the third radio frequency signal based on the local oscillator light and the second polarization signal light in the fourth optical signal after the lower sideband is filtered out.

[0038] The fourth demodulation submodule 125 is used to filter out the upper sideband of the fifth optical signal and to generate the fourth radio frequency signal based on the local oscillator light and the second polarization signal light in the fifth optical signal after the upper sideband is filtered out.

[0039] In a specific implementation, the four adjustment sub-modules of the adjustment module 12 can each process one radio frequency signal. Since the optical signals processed by the third demodulation sub-module 124 and the fourth demodulation sub-module 125 are optical signals obtained by rotating and splitting by the rotating splitter module 121, the receiving end does not need to match the phase of the local oscillator light and the signal light, and is not easily affected by phase changes caused by the environment.

[0040] In one embodiment, the structural schematic diagram of the optical millimeter-wave receiver can be as follows: Figure 3 As shown, the rotating splitter module 121 includes an optical circulator 1211, a wavelength division multiplexer 1212, a first fiber optic mirror 1213, a second fiber optic mirror 1215, a Faraday rotator 1214, and a second coupler 1216.

[0041] The first port of the optical circulator 1211 is connected to the first coupler 11. The second port of the optical circulator 1211 is connected to the first fiber optic mirror 1213, the second fiber optic mirror 1215 and the Faraday rotator 1214 respectively through the wavelength division multiplexer 1212. The third port of the optical circulator 1211 is connected to the second coupler 1216.

[0042] In a specific implementation, the first coupler 11 inputs the split third optical signal to the wavelength division multiplexer 1212 through the first port of the optical circulator 1211. The wavelength division multiplexer 1212 can separate the local oscillator light and the signal light of the third optical signal. The local oscillator light of the third optical signal is input to the Faraday rotator mirror 1214, and the signal light of the third optical signal is input to the first fiber optic mirror 1213 and the second fiber optic mirror 1215 respectively. The Faraday rotator mirror 1214 can rotate the polarization state of the local oscillator light of the third optical signal by 90°. The first fiber optic mirror 1213 and the second fiber optic mirror 1215 do not have rotation functions and will not change the polarization state of the signal light of the third optical signal. After the upper and lower sidebands of the local oscillator light and the signal light of the third optical signal are wavelength divided and coupled again, the polarization state of the rotated local oscillator light is the same as the polarization state of the second polarized signal light and orthogonal to the polarization state of the first polarized signal light. Using two fiber optic mirrors with a Faraday rotator, the task of rotating the circuit can be completed accurately and quickly.

[0043] In one embodiment, the structural schematic diagram of the optical millimeter-wave receiver can be as follows: Figure 4 As shown, the first sub-demodulation module 122 includes a first optical filter 1221 and a first photodetector 1222 connected to the first optical filter 1221; the second sub-demodulation module 123 includes a second optical filter 1231 and a second photodetector 1232 connected to the second optical filter 1231; the third sub-demodulation module 124 includes a third optical filter 1241 and a third photodetector 1242 connected to the third optical filter 1241; and the fourth sub-demodulation module 125 includes a fourth optical filter 1251 and a fourth photodetector 1252 connected to the fourth optical filter 1251.

[0044] The first optical filter 1221 is used to filter out the lower sideband of the first optical signal.

[0045] The first photodetector 1222 is used to capture the first radio frequency signal based on the local oscillator light and the first polarization signal light in the first optical signal after the lower sideband is filtered out.

[0046] In a specific implementation, the first optical filter 1221 only allows the upper sideband of the signal light and the local oscillator light of the first optical signal to pass through, while filtering out the lower sideband of the signal light. The upper sideband of the signal light and the local oscillator light of the first optical signal enter the first photodetector 1222. At this time, the optical signal entering the photodetector 1222 includes the local oscillator light, the upper sideband of the first polarized signal light, and the upper sideband of the second polarized signal light. The local oscillator light and the upper sideband of the first polarized signal light can capture the first radio frequency signal. Since the polarization state of the local oscillator light is orthogonal to the polarization state of the upper sideband of the second polarized signal light, the radio frequency signal cannot be captured.

[0047] The second optical filter 1231 is used to filter out the upper sideband of the second optical signal.

[0048] The second photodetector 1232 is used to capture a second radio frequency signal based on the local oscillator light and the first polarized signal light in the second optical signal after the upper sideband is filtered out.

[0049] In a specific implementation, the second optical filter 1231 only allows the lower sideband of the signal light and the local oscillator light of the second optical signal to pass through, while filtering out the upper sideband of the signal light. The lower sideband of the signal light and the local oscillator light of the second optical signal enter the second photodetector 1232. At this time, the optical signal entering the photodetector 1232 includes the local oscillator light, the lower sideband of the first polarized signal light, and the lower sideband of the second polarized signal light. The local oscillator light and the lower sideband of the first polarized signal light can capture the second radio frequency signal. However, since the polarization state of the local oscillator light is orthogonal to the polarization state of the lower sideband of the second polarized signal light, the radio frequency signal cannot be captured.

[0050] The third optical filter 1241 is used to filter out the lower sideband of the fourth optical signal.

[0051] The third photodetector 1242 is used to capture the third radio frequency signal based on the local oscillator light and the second polarization signal light in the fourth optical signal after the lower sideband is filtered out.

[0052] In a specific implementation, the third optical filter 1241 only allows the upper sideband of the signal light and the local oscillator light of the fourth optical signal to pass through, while filtering out the lower sideband of the signal light. The upper sideband of the signal light and the local oscillator light of the fourth optical signal enter the third photodetector 1242. At this time, the optical signal entering the photodetector 1242 includes the local oscillator light, the upper sideband of the first polarized signal light, and the upper sideband of the second polarized signal light. The local oscillator light and the upper sideband of the second polarized signal light can capture the third radio frequency signal. However, since the polarization state of the local oscillator light is orthogonal to the polarization state of the upper sideband of the first polarized signal light, the radio frequency signal cannot be captured.

[0053] The fourth optical filter 1251 is used to filter out the upper sideband of the fifth optical signal.

[0054] The fourth photodetector 1252 is used to capture the fourth radio frequency signal based on the local oscillator light and the second polarization signal light in the fifth optical signal after the upper sideband is filtered out.

[0055] In a specific implementation, the fourth optical filter 1251 only allows the lower sideband of the signal light of the fifth optical signal and the local oscillator light to pass through, while filtering out the upper sideband of the signal light. The lower sideband of the signal light of the fifth optical signal and the local oscillator light enter the fourth photodetector 1252. At this time, the optical signal entering the photodetector 1252 includes the local oscillator light, the lower sideband of the first polarized signal light, and the lower sideband of the second polarized signal light. The lower sideband of the local oscillator light and the lower sideband of the second polarized signal light can capture the fourth radio frequency signal. However, since the polarization state of the local oscillator light is orthogonal to the polarization state of the lower sideband of the first polarized signal light, the radio frequency signal cannot be captured.

[0056] Another embodiment of this application relates to an optical millimeter-wave transmitter. The implementation details of the optical millimeter-wave transmitter of this embodiment are described below. The following details are provided for ease of understanding and are not essential for implementing this solution.

[0057] A schematic diagram of the optical millimeter-wave transmitter in this embodiment can be seen as follows: Figure 5 As shown, it includes: laser 13, third coupler 14, modulator 15, polarization controller 16 and fourth coupler 17.

[0058] Laser 13 is connected to third coupler 14, third coupler 14 is connected to modulator 15 and polarization controller 16, and modulator 15 and polarization controller 16 are both connected to fourth coupler 17.

[0059] Laser 13 is used to emit laser light.

[0060] The third coupler 14 is used to split the laser emitted by the laser 13 into a first path of light for carrying the modulation signal and a second path of light as the local oscillator light.

[0061] The modulator 15 is used to modulate the first radio frequency signal onto the upper sideband of the first polarization state optical carrier of the first light, modulate the second radio frequency signal onto the lower sideband of the first polarization state optical carrier of the first light to obtain the first polarization signal light carrying the modulation signal, modulate the third radio frequency signal onto the upper sideband of the second polarization state optical carrier of the first light, and modulate the fourth radio frequency signal onto the lower sideband of the second polarization state optical carrier of the first light to obtain the second polarization signal light carrying the modulation signal.

[0062] In the specific implementation, the polarization state of the first polarization signal light is orthogonal to the polarization state of the second polarization signal light. The modulator 15 modulates a total of four radio frequency signals, realizing the transmission of four independent signals on one optical carrier.

[0063] The polarization controller 16 is used to adjust the polarization state of the local oscillator light to be the same as the polarization state of the first polarization signal light.

[0064] The fourth coupler 17 is used to combine the first polarized signal light, the second polarized signal light and the local oscillator light into a bundle and then input it into the optical fiber link for transmission.

[0065] Another embodiment of this application relates to an optical millimeter-wave wireless system. The implementation details of this embodiment's optical millimeter-wave wireless system are described below. The following details are provided for ease of understanding and are not essential for implementing this solution. A schematic diagram of this embodiment's optical millimeter-wave wireless system can be seen as follows: Figure 6 As shown, it includes a receiver and a transmitter, which are connected by a single-mode optical fiber. The receiver includes a first coupler 11 and a demodulation module 12, and the transmitter includes a laser 13, a third coupler 14, a modulator 15, a polarization controller 16, and a fourth coupler 17.

[0066] It is worth mentioning that all modules involved in the above embodiments are logical modules. In practical applications, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. Furthermore, to highlight the innovative aspects of this invention, the above embodiments do not include units that are not closely related to solving the technical problems proposed in this application; however, this does not mean that other units are absent in these embodiments.

[0067] Another embodiment of this application relates to an optical millimeter-wave demodulation method. The implementation details of the optical millimeter-wave demodulation method of this embodiment are described below. The following details are provided for ease of understanding and are not essential for implementing this solution. The flowchart of the optical millimeter-wave demodulation method of this embodiment can be seen as follows: Figure 7 As shown, it includes:

[0068] Step 201: Divide the received optical signal into a first optical signal, a second optical signal, and a third optical signal.

[0069] In a specific implementation, each optical signal includes a local oscillator light and a signal light. The signal light includes a first polarized signal light and a second polarized signal light. The upper sideband of the first polarized signal light is modulated with a first radio frequency (RF) signal, and the lower sideband of the first polarized signal light is modulated with a second RF signal. The upper sideband of the second polarized signal light is modulated with a third RF signal, and the lower sideband of the second polarized signal light is modulated with a fourth RF signal. The polarization state of the first polarized signal light is orthogonal to the polarization state of the second polarized signal light, and the polarization state of the local oscillator light is the same as the polarization state of the first polarized signal light.

[0070] Step 202: Rotate the polarization state of the local oscillator light in the third optical signal, and then split the rotated third optical signal into a fourth optical signal and a fifth optical signal.

[0071] Specifically, the polarization state of the rotated local oscillator light is the same as that of the second polarized signal light.

[0072] Step 203: Filter out the lower sideband of the first optical signal, the upper sideband of the second optical signal, the lower sideband of the fourth optical signal, and the upper sideband of the fifth optical signal respectively to obtain the first radio frequency signal, the second radio frequency signal, the third radio frequency signal, and the fourth radio frequency signal.

[0073] It is not difficult to see that this embodiment is a method embodiment corresponding to the above-described optical millimeter-wave receiver embodiment, and this embodiment can be implemented in conjunction with the above-described optical millimeter-wave receiver embodiment. The relevant technical details and effects mentioned in the above-described optical millimeter-wave receiver embodiment are still valid in this embodiment, and will not be repeated here to reduce repetition. Correspondingly, the relevant technical details mentioned in this embodiment can also be applied to the above-described optical millimeter-wave receiver embodiment.

[0074] In one embodiment, filtering out the lower sideband of the first optical signal, the upper sideband of the second optical signal, the lower sideband of the fourth optical signal, and the upper sideband of the fifth optical signal to obtain the first, second, third, and fourth radio frequency signals can be achieved by, as follows: Figure 8 The steps shown are implemented as follows:

[0075] Step 301: Filter out the lower sideband of the first optical signal, and capture the first radio frequency signal based on the local oscillator light and the first polarization signal light in the first optical signal after the lower sideband is filtered out.

[0076] Step 302: Filter out the upper sideband of the second optical signal, and capture the second radio frequency signal based on the local oscillator light and the first polarization signal light in the second optical signal after the upper sideband is filtered out.

[0077] Step 303: Filter out the lower sideband of the fourth optical signal, and capture the third radio frequency signal based on the local oscillator light and the second polarized signal light in the fourth optical signal after the lower sideband is filtered out.

[0078] Step 304: Filter out the upper sideband of the fifth optical signal, and capture the fourth radio frequency signal based on the local oscillator light and the second polarized signal light in the fifth optical signal after the upper sideband is filtered out.

[0079] Another embodiment of this application relates to an optical millimeter-wave modulation method. The implementation details of the optical millimeter-wave modulation method of this embodiment are described below. The following details are provided for ease of understanding and are not essential for implementing this solution. The flowchart of the optical millimeter-wave modulation method of this embodiment can be seen as follows: Figure 9 As shown, it includes:

[0080] Step 401: The laser emitted by the laser is divided into a first path of light for carrying the modulation signal and a second path of light as the local oscillator light.

[0081] Step 402: Modulate the first radio frequency signal onto the upper sideband of the first polarization state optical carrier of the first light, and modulate the second radio frequency signal onto the lower sideband of the first polarization state optical carrier of the first light, to obtain the first polarization signal light carrying the modulation signal.

[0082] Step 403: Modulate the third radio frequency signal onto the upper sideband of the second polarization state optical carrier of the first light, and modulate the fourth radio frequency signal onto the lower sideband of the second polarization state optical carrier of the first light, to obtain the second polarization signal light carrying the modulation signal.

[0083] Step 404: Adjust the polarization state of the local oscillator light to be the same as the polarization state of the first polarization signal light.

[0084] Step 405: Combine the first polarized signal light, the second polarized signal light, and the local oscillator light, and then input them into the optical fiber link for transmission.

[0085] It is not difficult to see that this embodiment is a method embodiment corresponding to the above-described optical millimeter-wave transmitter embodiment, and this embodiment can be implemented in conjunction with the above-described optical millimeter-wave transmitter embodiment. The relevant technical details and effects mentioned in the above-described optical millimeter-wave transmitter embodiment are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the above-described optical millimeter-wave transmitter embodiment.

[0086] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this application.

Claims

1. An optical millimeter-wave receiver, characterized in that, include: A first coupler is used to split the received optical signal into a first optical signal, a second optical signal, and a third optical signal; wherein each optical signal includes a local oscillator light and a signal light, the signal light includes a first polarized signal light and a second polarized signal light, the upper sideband of the first polarized signal light is modulated with a first radio frequency signal, the lower sideband of the first polarized signal light is modulated with a second radio frequency signal, the upper sideband of the second polarized signal light is modulated with a third radio frequency signal, the lower sideband of the second polarized signal light is modulated with a fourth radio frequency signal, the polarization state of the first polarized signal light is orthogonal to the polarization state of the second polarized signal light, and the polarization state of the local oscillator light is the same as the polarization state of the first polarized signal light; The demodulation module is used to rotate the polarization state of the local oscillator light in the third optical signal, and then split the rotated third optical signal into a fourth optical signal and a fifth optical signal. By filtering out the lower sideband of the first optical signal, the upper sideband of the second optical signal, the lower sideband of the fourth optical signal, and the upper sideband of the fifth optical signal, the module obtains the first radio frequency signal, the second radio frequency signal, the third radio frequency signal, and the fourth radio frequency signal. The polarization state of the rotated local oscillator light is the same as the polarization state of the second polarized signal light.

2. The optical millimeter-wave receiver according to claim 1, characterized in that, The demodulation module includes: The rotation splitter module is used to rotate the polarization state of the local oscillator light in the third optical signal, and then split the rotated third optical signal into a fourth optical signal and a fifth optical signal.

3. The optical millimeter-wave receiver according to claim 2, characterized in that, The demodulation module further includes: The first demodulation submodule is used to filter out the lower sideband of the first optical signal and to capture the first radio frequency signal based on the local oscillator light and the first polarized signal light in the first optical signal after the lower sideband is filtered out. The second demodulation submodule is used to filter out the upper sideband of the second optical signal and to extract the second radio frequency signal based on the local oscillator light and the first polarized signal light in the second optical signal after the upper sideband is filtered out. The third demodulation submodule is used to filter out the lower sideband of the fourth optical signal and to extract the third radio frequency signal based on the local oscillator light and the second polarization signal light in the fourth optical signal after the lower sideband is filtered out. The fourth demodulation submodule is used to filter out the upper sideband of the fifth optical signal and to extract the fourth radio frequency signal based on the local oscillator light and the second polarization signal light in the fifth optical signal after the upper sideband is filtered out.

4. The optical millimeter-wave receiver according to claim 2, characterized in that, The rotating splitter module includes: an optical circulator, a wavelength division multiplexer, a first fiber optic mirror, a second fiber optic mirror, a Faraday rotator, and a second coupler; The first port of the optical circulator is connected to the first coupler, the second port of the optical circulator is connected to the first fiber optic mirror, the second fiber optic mirror and the Faraday rotator through the wavelength division multiplexer, and the third port of the optical circulator is connected to the second coupler.

5. The optical millimeter-wave receiver according to claim 3, characterized in that, The first demodulation submodule includes: a first optical filter and a first photodetector connected to the first optical filter; The first optical filter is used to filter out the lower sideband of the first optical signal; The first photodetector is used to capture the first radio frequency signal based on the local oscillator light and the first polarized signal light in the first optical signal after the lower sideband is filtered out; The second demodulation submodule includes: a second optical filter and a second photodetector connected to the second optical filter; The second optical filter is used to filter out the upper sideband of the second optical signal; The second photodetector is used to capture the second radio frequency signal based on the local oscillator light and the first polarized signal light in the second optical signal after the upper sideband is filtered out; The third demodulation submodule includes: a third optical filter and a third photodetector connected to the third optical filter; The third optical filter is used to filter out the lower sideband of the fourth optical signal; The third photodetector is used to capture the third radio frequency signal based on the local oscillator light and the second polarized signal light in the fourth optical signal after the lower sideband is filtered out. The fourth demodulation submodule includes: a fourth optical filter and a fourth photodetector connected to the fourth optical filter; The fourth optical filter is used to filter out the upper sideband of the fifth optical signal; The fourth photodetector is used to capture the fourth radio frequency signal based on the local oscillator light and the second polarized signal light in the fifth optical signal after the upper sideband is filtered out.

6. An optical millimeter-wave wireless system, characterized in that, It includes a receiver for optically transmitted millimeter waves as described in any one of claims 1 to 5, and a transmitter for optically transmitted millimeter waves.

7. A method for demodulating optical millimeter waves, characterized in that, include: The received optical signal is divided into a first optical signal, a second optical signal, and a third optical signal; each optical signal includes a local oscillator light and a signal light. The signal light includes a first polarized signal light and a second polarized signal light. The upper sideband of the first polarized signal light is modulated with a first radio frequency (RF) signal, and the lower sideband of the first polarized signal light is modulated with a second RF signal. The upper sideband of the second polarized signal light is modulated with a third RF signal, and the lower sideband of the second polarized signal light is modulated with a fourth RF signal. The polarization state of the first polarized signal light is orthogonal to the polarization state of the second polarized signal light, and the polarization state of the local oscillator light is the same as the polarization state of the first polarized signal light. The polarization state of the local oscillator light in the third optical signal is rotated, and the rotated third optical signal is divided into a fourth optical signal and a fifth optical signal; wherein the polarization state of the rotated local oscillator light is the same as the polarization state of the second polarized signal light; The lower sideband of the first optical signal, the upper sideband of the second optical signal, the lower sideband of the fourth optical signal, and the upper sideband of the fifth optical signal are filtered out respectively to obtain the first radio frequency signal, the second radio frequency signal, the third radio frequency signal, and the fourth radio frequency signal.

8. The optical millimeter-wave demodulation method according to claim 7, characterized in that, The step of filtering out the lower sideband of the first optical signal, the upper sideband of the second optical signal, the lower sideband of the fourth optical signal, and the upper sideband of the fifth optical signal to obtain the first radio frequency signal, the second radio frequency signal, the third radio frequency signal, and the fourth radio frequency signal includes: The lower sideband of the first optical signal is filtered out, and the first radio frequency signal is generated based on the local oscillator light and the first polarization signal light in the first optical signal after the lower sideband is filtered out. The upper sideband of the second optical signal is filtered out, and the second radio frequency signal is generated based on the local oscillator light and the first polarization signal light in the second optical signal after the upper sideband is filtered out. The lower sideband of the fourth optical signal is filtered out, and the third radio frequency signal is generated based on the local oscillator light and the second polarization signal light in the fourth optical signal after the lower sideband is filtered out. The upper sideband of the fifth optical signal is filtered out, and the fourth radio frequency signal is generated based on the local oscillator light and the second polarization signal light in the fifth optical signal after the upper sideband is filtered out.

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