CN111416662A - Signal generation and transmission system and method based on polarization multiplexing double MZM modulator - Google Patents

Abstract

The invention discloses a signal generation and transmission system and method based on polarization multiplexing dual MZM modulators. The system includes a central computer room end, a wired end and a mobile end; the central computer room end includes a distributed feedback laser, a local oscillator, a polarization multiplexing modulation The polarization multiplexing modulator integrates the first MZM modulator, the second MZM modulator, the polarization beam splitter and the polarization beam combiner, and the local oscillator passes through the The frequency multiplier is connected with a mixer, and the output end of the polarization beam combiner is connected with a fiber amplifier; the wired end includes an optical filter, a first photodetector, a second photodetector, a first power amplifier, a second power amplifier, a transmitting antenna and a first signal processor; the mobile terminal includes a receiving antenna, a third power amplifier and a second signal processor. The system of the invention has a reasonable structure, can be effectively applied in large-capacity wired and wireless mixed transmission communication, has good use effect, and is convenient for popularization and use.

Description

Signal generation and transmission system and method based on polarization multiplexing dual MZM modulators

technical field

The invention belongs to the technical field of communication, and in particular relates to a signal generation and transmission system and method based on polarization multiplexing dual MZM modulators.

Background technique

With the rapid growth of communication services in big data, cloud computing, artificial intelligence, the Internet of Things and mobile Internet, the existing optical access network is difficult to meet the future multi-functional, large-capacity wired and wireless hybrid transmission requirements, and the development of a new generation of high-speed, broadband Wired and wireless hybrid communication access network technology has become a more urgent demand at present. The optical and wireless fusion communication technology combines the broadband wireless transmission of millimeter waves and the large-capacity transmission of optical fibers, which can not only effectively overcome the bandwidth bottleneck of electronic devices, but also double the transmission rate of wireless signals. Optical and wireless converged communication systems can generate and transmit wired and wireless signals at the same time, and have broad application prospects in access network systems such as fiber-to-the-home, fiber-to-office, and fiber-to-the-building.

In the prior art, there are the following two types of solutions for the hybrid transmission and access system of wired signals and wireless signals:

1. Based on the hybrid transmission scheme of wired and wireless signals based on wavelength division multiplexing devices, at the transmitting end, optical transmitters of different signal types can be connected to the optical wavelength division multiplexer. Among them, the modulation methods and types of the transmitters are different. Restricted, the modulated carrier signal sent by the transmitter is transmitted to the input end of the wavelength division multiplexer using optical fiber. The optical wavelength division multiplexer is a multi-input single-output device, each input port corresponds to a specific wavelength input, and the optical wavelength division multiplexer multiplexes all the input optical signals into one optical fiber for transmission. At the receiving end, a device that is the same as the optical wavelength division multiplexer is used, and it is used in reverse connection. Output, complete the demultiplexing of the optical signal, the optical signals separated by the optical wave demultiplexer at the receiving end enter the corresponding receivers respectively, and each receiver completes the demodulation of the optical signal according to the corresponding modulation protocol, so that the original signal can be restored. Signal. This kind of multi-signal mixed transmission system based on optical wavelength division multiplexing device can realize the simultaneous transmission of multiple or multiple signals. The type or quantity of transmitted signals only depends on the number of input and output ports of the wavelength division multiplexer. The generating and receiving devices are independent of each other, and each signal occupies one channel (wavelength). However, each channel or each transmitter cannot generate a mixed signal (wireless and wired) simultaneously. In addition, the increase in transmission capacity in this way depends on the number of transmitters and receivers, the number of signal generators and the number of devices used. Proportional, so the system cost is higher, this structure is rarely used in access network systems.

2. MZM-based mixed-signal transmission scheme, including a system based on a single MZM (Mach-Zehnder Modulator) to simultaneously generate and transmit wired and wireless hybrid systems and a system based on dual MZMs to simultaneously generate and transmit wired and wireless hybrid signals. A single MZM generates and transmits wired and wireless hybrid systems at the same time. In the system, wired data and wireless data can be modulated to the two arms of the MZM respectively, or the two kinds of data can be mixed and then modulated to one of the arms of the MZM. The system can perform vector signal Transmission, non-vector signal transmission can also be performed; a system based on dual MZMs to generate and transmit wired and wireless mixed signals at the same time. Dual MZMs are integrated into one module, and wired data and wireless data can be modulated to each MZM separately, or both can be combined. After the data is mixed and modulated into one of the MZMs, the system can perform vector signal transmission or non-vector signal transmission. Whether it is a single MZM scheme or two MZM schemes, the wired data is generally modulated to the center carrier emitted by the light source. The wireless data is modulated to the MZM to generate an optical sideband signal. At the receiving end, an optical filter is used to separate the two kinds of signals, and then the optical receivers are used to demodulate the corresponding transmission signals, so as to restore the original signal. The above two wired and wireless mixed signal generation and transmission systems have simple structures and low cost, and are very suitable for application scenarios such as fiber-to-the-home, fiber-to-office, and fiber-to-building. However, since the modulator used is limited by the electronic bandwidth, as the modulation rate increases, the signal-to-noise ratio of the modulated optical carrier signal decreases sharply, so the potential for further improving the transmission rate is limited. In addition, in order to reduce the mutual interference of wired data and wireless data in the process of generation and transmission, and improve the signal-to-noise ratio of the channel, a high-performance optical filter is required at the receiving end, which is not conducive to the reduction of system cost.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a signal generation and transmission system based on polarization multiplexing dual MZM modulators in view of the above-mentioned deficiencies in the prior art. In the communication with wireless hybrid transmission, the construction cost of the signal generation and transmission system is reduced, the signal transmission is efficient and stable, the use effect is good, and it is easy to popularize and use.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is: a signal generation and transmission system based on polarization multiplexing dual MZM modulators, including a central computer room end that simultaneously generates wired signals and wireless signals, and wired transmission with the central computer room end The wired end and the mobile end that performs wireless transmission with the wired end; the central computer room end includes a distributed feedback laser, a local oscillator and a polarization multiplexing modulator, and a first wireless data signal for converting a wireless data signal into a baseband electrical signal. A code converter and a second code converter for converting a wired data signal into a baseband electrical signal; the polarization multiplexing modulator integrates a first MZM modulator, a second MZM modulator, and a polarization beam splitter and polarization beam combiner, the first MZM modulator and the second MZM modulator are both connected with the output end of the polarization beam splitter, and the first MZM modulator and the second MZM modulator are both connected with the polarization beam combiner The output end of the distributed feedback laser is connected with a polarization controller, the polarization beam splitter is connected with the output end of the polarization controller, and the output end of the local oscillator is connected with a frequency multiplier, so The output end of the frequency multiplier is connected with a mixer, the first code type converter is connected with the input end of the mixer, the output end of the mixer is connected with a first radio frequency amplifier, the first MZM The modulator is connected to the output end of the first radio frequency amplifier, the output end of the second code-type converter is connected to the second radio frequency amplifier, the second MZM modulator is connected to the output end of the second radio frequency amplifier, the first An input end of an MZM modulator is connected with a first DC bias power supply, an input end of the second MZM modulator is connected with a second DC bias power supply, and an output end of the polarization beam combiner is connected with a fiber amplifier; The wired end includes an optical filter, the optical filter is connected to the output end of the optical fiber amplifier, the output end of the optical filter is connected with a first photodetector and a second photodetector, and the first photodetector is connected to the output end of the optical filter. The output of the detector is connected with a first power amplifier, the output of the first power amplifier is connected with a transmitting antenna, the output of the second photodetector is connected with a second power amplifier, and the output of the second power amplifier is connected A first signal processor is connected to the terminal; the mobile terminal includes a receiving antenna for receiving wireless signals transmitted by the transmitting antenna, the output terminal of the receiving antenna is connected with a third power amplifier, and the output terminal of the third power amplifier A second signal processor is connected.

In the above-mentioned signal generation and transmission system based on polarization multiplexing dual MZM modulators, the fiber amplifier is a polarization-maintaining erbium-doped fiber amplifier.

The above-mentioned signal generation and transmission system based on polarization multiplexing dual MZM modulators, between the polarization beam splitter and the first MZM modulator, between the polarization beam splitter and the second MZM modulator, and between the polarization beam splitter and the second MZM modulator. Both the first MZM modulator and the polarization beam combiner and the second MZM modulator and the polarization beam combiner are connected by a polarization-maintaining single-mode fiber.

The above-mentioned signal generation and transmission system based on polarization multiplexing dual MZM modulators, between the distributed feedback laser and the polarization controller, between the polarization controller and the polarization beam splitter, between the polarization beam combiner and the optical fiber The amplifiers and between the optical fiber amplifier and the optical filter are connected by single-mode optical fibers.

In the above signal generation and transmission system based on polarization multiplexing dual MZM modulators, both the transmitting antenna and the receiving antenna are Cassegrain antennas.

The invention also discloses a method for signal generation and transmission based on the polarization multiplexing dual MZM modulator, the method comprising the following steps:

Step 1. The distributed feedback laser emits a coherent and continuous light source signal with a frequency of f _c , and after the polarization controller is used to control the polarization of the optical signal, the optical signal is incident on the polarization multiplexing modulator;

Step 2: The polarization beam splitter in the polarization multiplexing modulator separates the polarization state of the optical signal, and the separated two-path optical signals are respectively incident on the first MZM modulator and the second MZM modulator. The first DC bias power supply DC biases the first MZM modulator at the minimum transmission point, and the second DC bias power supply DC biases the second MZM modulator at the quadrature point;

Step 3: The first code converter converts the wireless data signal to be transmitted into a baseband electrical signal, and the baseband electrical signal is transmitted to the mixer through a high-frequency coaxial cable; at the same time, the local oscillator generates a frequency of The sine or cosine radio frequency signal of f _s , the radio frequency signal is acted by the frequency multiplier, the radio frequency signal is boosted by an integer multiple to become nf _s , and then transmitted to the mixer through the high frequency coaxial cable, and mixed with the baseband electrical signal , get the radio frequency electrical signal;

Step 4: The first radio frequency amplifier amplifies the radio frequency electrical signal, the amplified radio frequency electrical signal drives the first MZM modulator, and the first MZM modulator performs carrier suppression on the amplified radio frequency electrical signal to generate a signal for transmission. The optical millimeter wave signal of the wireless signal, the optical millimeter wave signal is transmitted to the polarization beam combiner;

Step 5: The second code type converter converts the wired data signal to be transmitted into a baseband electrical signal, and the baseband electrical signal is transmitted to the second radio frequency amplifier through a high-frequency coaxial cable for amplification, and the amplified baseband electrical signal is directly Drive the second MZM modulator to generate an optical carrier signal and transmit it to the polarization beam combiner;

Step 6: The polarized optical beam combiner couples the optical millimeter wave signal and the optical carrier signal into the same optical fiber, and the coupled optical signal is amplified by the optical fiber amplifier, and then transmitted to the optical filter through the single-mode optical fiber;

Step 7. The optical filter at the wired end separates the coupled optical signals carrying different data, wherein the separated optical millimeter-wave signal is incident on the first photodetector to generate an electrical millimeter-wave signal, and the electrical millimeter-wave signal passes through. After the first power amplifier is amplified, it is converted into a wireless electric millimeter wave signal through the transmitting antenna and sent to the space; at the same time, the separated optical carrier signal passes through the second photodetector and the second power amplifier in sequence, and then passes through the first power amplifier. The signal processor performs signal processing to recover the wired data signal;

Step 8: The receiving antenna of the mobile terminal receives the wireless electric millimeter wave signal in the space. After the received electric millimeter wave signal is amplified by the third power amplifier, the signal is processed by the second signal processor to recover the wireless data signal. .

Compared with the prior art, the present invention has the following advantages:

1. The system structure of the present invention is reasonable in design and convenient in implementation.

2. The present invention uses a polarization multiplexing modulator to replace the existing single MZM modulator or dual MZM modulator, uses the second MZM modulator to modulate the wired signal on the central optical carrier, and uses the optical millimeter wave generated by the first MZM modulator. The signal realizes the transmission of wireless signals. Due to the polarization multiplexing dual MZM modulator structure, the optical signals generated by the two MZM modulators are a pair of mutually orthogonal polarized lights. Therefore, the two signals can independently generate vector signals or non-polarized light. vector signals, and will not interfere with each other during transmission; in addition, since the polarization directions of the two optical signals are orthogonal to each other, at the receiving end, the performance of the optical filter that separates the two optical signals is not high, even if the optical The filter cannot completely separate the two signals, nor does it affect the reception of the signal, so that the channel has a higher signal-to-noise ratio and further reduces the construction cost of the system.

3. The present invention can be effectively applied in large-capacity wired and wireless hybrid transmission communication, reduces the construction cost of a signal generation and transmission system, has efficient and stable signal transmission, good use effect, and is easy to popularize and use.

To sum up, the system of the present invention has reasonable structure design, convenient implementation, can be effectively applied in large-capacity wired and wireless mixed transmission communication, reduces the construction cost of the signal generation and transmission system, has efficient and stable signal transmission, good use effect, and is easy to popularize. use.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the system structure principle block diagram of the present invention;

FIG. 2 is a bit error rate curve of a wireless signal and a wired signal of the present invention under the condition of different optical carrier incident optical powers.

Explanation of reference numbers:

1—distributed feedback laser; 2—local oscillator; 3—polarization multiplexing modulator;

3-1—first MZM modulator; 3-2—second MZM modulator; 3-3—polarized beam splitter;

3-4—polarized beam combiner; 4—first code converter; 5—second code converter;

6—polarization controller; 7—frequency multiplier; 8—mixer;

9—the first radio frequency amplifier; 10—the second radio frequency amplifier; 11—the first DC bias power supply;

12—second DC bias power supply; 13—fiber amplifier; 14—optical filter;

15—the first photodetector; 16—the second photodetector; 17—the first power amplifier;

18—transmitting antenna; 19—second power amplifier; 20—first signal processor;

21—receiving antenna; 22—third power amplifier; 23—second signal processor.

Detailed ways

As shown in FIG. 1, the signal generation and transmission system based on polarization multiplexing dual MZM modulators of the present invention includes a central computer room end that generates wired signals and wireless signals at the same time, a wired end that performs wired transmission with the central computer room end, and a wired end The mobile terminal for wireless transmission at the terminal; the central computer room terminal includes a distributed feedback laser 1, a local oscillator 2 and a polarization multiplexing modulator 3, and a first code type converter for converting wireless data signals into baseband electrical signals 4 and the second code type converter 5 for converting the wired data signal into a baseband electrical signal; the polarization multiplexing modulator 3 is integrated with the first MZM modulator 3-1, the second MZM modulator 3-2, The polarizing beam splitter 3-3 and the polarizing beam combiner 3-4, the first MZM modulator 3-1 and the second MZM modulator 3-2 are both connected to the output end of the polarizing beam splitter 3-3 , the first MZM modulator 3-1 and the second MZM modulator 3-2 are all connected with the input end of the polarization beam combiner 3-4, and the output end of the distributed feedback laser 1 is connected with a polarization controller 6, The polarization beam splitter 3-3 is connected with the output end of the polarization controller 6, the output end of the local oscillator 2 is connected with a frequency multiplier 7, and the output end of the frequency doubler 7 is connected with a mixer 8. The first code converter 4 is connected to the input end of the mixer 8, the output end of the mixer 8 is connected to the first radio frequency amplifier 9, and the first MZM modulator 3-1 is connected to the first radio frequency amplifier 9. The output end of a radio frequency amplifier 9 is connected, the output end of the second code converter 5 is connected with the second radio frequency amplifier 10, the second MZM modulator 3-2 is connected with the output end of the second radio frequency amplifier 10, The input terminal of the first MZM modulator 3-1 is connected with a first DC bias power supply 11, the input terminal of the second MZM modulator 3-2 is connected with a second DC bias power supply 12, and the polarization The output end of the optical beam combiner 3-4 is connected with a fiber amplifier 13; the wired end includes an optical filter 14, the optical filter 14 is connected with the output end of the fiber amplifier 13, and the output end of the optical filter 14 is connected to There are a first photodetector 15 and a second photodetector 16, the output end of the first photodetector 15 is connected with a first power amplifier 17, and the output end of the first power amplifier 17 is connected with a transmitting antenna 18, The output end of the second photodetector 16 is connected with a second power amplifier 19, and the output end of the second power amplifier 19 is connected with the first signal processor 20; The receiving antenna 21 of the wireless signal, the output end of the receiving antenna 21 is connected with a third power amplifier 22, and the output end of the third power amplifier 22 is connected with a second signal processor 23.

In this embodiment, the fiber amplifier 13 is a polarization-maintaining erbium-doped fiber amplifier.

In this embodiment, between the polarization beam splitter 3-3 and the first MZM modulator 3-1, between the polarization beam splitter 3-3 and the second MZM modulator 3-2, The first MZM modulator 3-1 and the polarization beam combiner 3-4 and between the second MZM modulator 3-2 and the polarization beam combiner 3-4 are connected through polarization maintaining single-mode fibers.

During specific implementation, the polarization-maintaining single-mode fiber ensures that the polarization direction of the optical signal remains unchanged during the transmission process between the devices.

In this embodiment, between the distributed feedback laser 1 and the polarization controller 6, between the polarization controller 6 and the polarization beam splitter 3-3, between the polarization beam combiner 3-4 and the fiber amplifier 13 The fiber amplifier 13 and the optical filter 14 are connected by single-mode fiber.

In this embodiment, the transmitting antenna 18 and the receiving antenna 21 are both Cassegrain antennas.

The method for signal generation and transmission based on polarization multiplexing dual MZM modulators of the present invention comprises the following steps:

Step 1, the distributed feedback laser 1 emits a coherent and continuous light source signal with a frequency f _c , and after the polarization controller 6 controls the polarization of the optical signal, the optical signal is incident on the polarization multiplexing modulator 3;

During specific implementation, the polarization controller 6 can adjust the optical power of the two separated polarized lights.

Step 2: The polarization beam splitter 3-3 in the polarization multiplexing modulator 3 separates the polarization state of the optical signal, and the separated two-path optical signals are respectively incident on the first MZM modulator 3-1 and the second MZM modulator 3-1. In the MZM modulator 3-2, the first DC bias power supply 11 DC biases the first MZM modulator 3-1 at the minimum transmission point, and the second DC bias power supply 12 DC biases the second MZM modulator 3-1. 3-2 DC bias at the quadrature point;

Step 3: The first code converter 4 converts the wireless data signal to be transmitted into a baseband electrical signal, and the baseband electrical signal is transmitted to the mixer 8 through a high-frequency coaxial cable; at the same time, the local oscillator 2 A sine or cosine radio frequency signal with a frequency of f _s is generated. The radio frequency signal is acted by the frequency multiplier 7, and the radio frequency signal is increased by an integer multiple to become nf _s , and then transmitted to the mixer 8 through the high-frequency coaxial cable, and the baseband The electrical signal is mixed to obtain a radio frequency electrical signal;

During specific implementation, the first code type converter 4 converts the wireless data signal to be transmitted into a baseband electrical signal, and the electrical signal may be a vector signal or a non-vector signal.

Step 4: The first radio frequency amplifier 9 amplifies the radio frequency electrical signal, the amplified radio frequency electrical signal drives the first MZM modulator 3-1, and the first MZM modulator 3-1 performs the amplification on the amplified radio frequency electrical signal. Carrier suppression, generating an optical millimeter-wave signal for transmitting wireless signals, and transmitting the optical millimeter-wave signal to the polarization beam combiner 3-4;

In specific implementation, since the first MZM modulator 3-1 is DC biased at the minimum transmission point, it works in the carrier suppression mode. Therefore, at the optical output end of the first MZM modulator 3-1, the central optical carrier is suppressed On both sides of the central optical carrier, many optical sideband signals are generated, and the wireless data is modulated on these optical sideband signals, and the positive and negative first-order sideband signals with a frequency interval of 2nf _s occupy the sideband optical signal. The main energy, using this pair of optical sideband signals as an optical millimeter wave signal, is used to transmit wireless signals.

Step 5: The second code type converter 5 converts the wired data signal to be transmitted into a baseband electrical signal, and the baseband electrical signal is transmitted to the second radio frequency amplifier 10 through a high-frequency coaxial cable for amplification, and the amplified baseband electrical signal is amplified. The signal directly drives the second MZM modulator 3-2, generates an optical carrier signal, and transmits it to the polarization beam combiner 3-4;

During specific implementation, the second code type converter 5 converts the wired data signal to be transmitted into a baseband electrical signal, and the electrical signal may be a vector signal or a non-vector signal; since the second MZM modulator 3-2 is biased at The quadrature point, therefore, the baseband electrical signal is directly modulated on the optical center carrier.

Step 6: The polarized optical beam combiner 3-4 couples the optical millimeter wave signal and the optical carrier signal into the same optical fiber, and the coupled optical signal is amplified by the optical fiber amplifier 13, and then transmitted to the optical filter 14 through the single-mode optical fiber;

Step 7. The optical filter 14 at the wired end separates the coupled optical signals carrying different data, wherein the separated optical millimeter-wave signal is incident on the first photodetector 15 to generate an electrical millimeter-wave signal, an electrical millimeter-wave signal. After the signal is amplified by the first power amplifier 17, it is converted into a wireless electric millimeter wave signal through the transmitting antenna 18 and sent to the space; at the same time, the separated optical carrier signal passes through the second photodetector 16 and the second power amplifier 19 in turn. After that, the first signal processor 20 performs signal processing to recover the wired data signal;

In specific implementation, the separated optical millimeter wave signal is incident on the first photodetector 15 whose bandwidth is matched with the first photodetector 15. According to the square detection law, the two first-order sideband signals (optical millimeter wave) will A heterodyne beat frequency occurs, thereby generating an electrical millimeter-wave signal whose frequency is equal to the frequency difference of the two optical millimeter-wave signals, ie, 2nf _s .

Step 8: The receiving antenna 21 of the mobile terminal receives the wireless electric millimeter wave signal in the space. After the received electric millimeter wave signal is amplified by the third power amplifier 22, the signal is processed by the second signal processor 23 to recover the signal. Wireless data signal.

In order to verify the technical effect that the present invention can produce, an experiment of simultaneously generating and transmitting a 10Gbps wired signal and a 4Gbps wireless signal is carried out on the signal generation and transmission system based on the polarization multiplexing dual MZM modulator of the present invention. The distributed feedback laser 1 emits a 1551.07nm continuous Lightwave, its linewidth is less than 100kHz, the transmit power is 10dBm, the half-wave voltage of the polarization multiplexing modulator 3 at 1GHz is about 3.5v, its 3dB bandwidth is 25GHz, the insertion loss is 6dB, the extinction ratio is 20dB, the local oscillator 2 Generate a cosine signal with a frequency of 19.11GHz, amplify it to 38.22GHz through a double frequency multiplier 7, and then mix it with a wireless signal with a peak-to-peak voltage of 0.5V and a rate of 4Gbps in the mixer 8. The mixed signal is amplified by a first radio frequency amplifier 9 with a saturated output power of 30 dBm and a frequency response range of 36 to 41 GHz, and the generated carrier multiplexing signal directly drives the first MZM in the polarization multiplexing modulator 3 The modulator 3-1, the first MZM modulator 3-1 is DC biased at its minimum transmission point by the first DC bias power supply 11 to realize carrier suppression modulation and generate a pair of optical sideband signals. The frequency interval of the band signal is 76.44GHz; the other channel has a wired signal with a peak-to-peak voltage of 0.5V and a rate of 10Gbps, which is amplified by a second RF amplifier 10 with a saturated output power of 30dBm and a frequency response range of 0 to 40GHz, and then The second MZM modulator 3-2 in the polarization multiplexing modulator 3 is directly driven, and the second MZM modulator 3-2 is DC biased at the quadrature point by the second DC bias power supply 12, so the wired signal is directly modulated to On the optical carrier; after the generated optical sideband signal and optical carrier signal are coupled into the single-mode fiber by the polarization beam combiner 3-4, the power is increased to 11dBm by an erbium-doped fiber amplifier, and then transmitted to the cable through the single-mode fiber. end.

At the wired end, an optical filter 14 with a resolution of 50/100GHz is used to separate the optical carrier and the optical sideband signal, and the separated optical sideband signal enters a first photodetector 15 with a 3dB bandwidth of 75GHz for external processing. beat frequency to obtain a 76.44GHz electric millimeter wave signal, the electric millimeter wave signal is then amplified by a W-band (75-110GHz) electronic amplifier (the first power amplifier 17), and then the electric millimeter wave signal is amplified by the transmitting antenna 18. The signal is transmitted to the mobile terminal; the other optical carrier signal separated by the optical filter 14 directly enters a second photodetector 16 with a 3dB bandwidth of 15GHz for detection, and then the binary level signal can be recovered by the decision circuit unit to realize wired transmission of data signals.

In the mobile terminal, another Cassegrain antenna (receiving antenna 21 ) identical to the transmitting antenna 18 is used to receive the wireless millimeter-wave signal, and the received millimeter-wave signal is again transmitted by a third millimeter-wave signal with a frequency of 0-30 GHz and a power of 20 dB. The power amplifier 22 amplifies, and then, the second signal processor 23 is used to complete the envelope detection, and the binary level signal can be recovered through the decision circuit unit, so as to realize the transmission of the wireless data signal.

It can be seen from FIG. 2 that both wired signals and wireless signals can realize bit error rate-free transmission by increasing the transmit optical power.

The above are only preferred embodiments of the present invention and do not limit the present invention. Any simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical essence of the present invention still belong to the technology of the present invention. within the scope of the program.

Claims (6)

1. a signal generation and transmission system based on polarization multiplexing dual MZM modulators, it is characterized in that: comprise the central computer room end that generates wired signal and wireless signal simultaneously and the wired end that carries out wired transmission with the central computer room end, and the wired end A mobile terminal for wireless transmission; The central computer room end includes a distributed feedback laser (1), a local oscillator (2), a polarization multiplexing modulator (3), and a first code converter (4) for converting wireless data signals into baseband electrical signals ) and a second code type converter (5) for converting wired data signals into baseband electrical signals; the polarization multiplexing modulator (3) is integrated with a first MZM modulator (3-1), a second MZM A modulator (3-2), a polarizing beam splitter (3-3) and a polarizing beam combiner (3-4), the first MZM modulator (3-1) and the second MZM modulator (3- 2) Both are connected to the output end of the polarization beam splitter (3-3), and the first MZM modulator (3-1) and the second MZM modulator (3-2) are both connected to the polarization beam combiner (3-3) -4) is connected to the input end, the output end of the distributed feedback laser (1) is connected with a polarization controller (6), the polarization beam splitter (3-3) is connected to the output end of the polarization controller (6) connected, the output of the local oscillator (2) is connected with a frequency multiplier (7), the output of the frequency multiplier (7) is connected with a mixer (8), and the first code converter (4) is connected to the input end of the mixer (8), the output end of the mixer (8) is connected with a first radio frequency amplifier (9), and the first MZM modulator (3-1) is connected to the first radio frequency amplifier (9). An output end of a radio frequency amplifier (9) is connected to the output end of the second code converter (5), a second radio frequency amplifier (10) is connected to the output end, and the second MZM modulator (3-2) is connected to the second radio frequency amplifier (3-2). The output end of the radio frequency amplifier (10) is connected, the input end of the first MZM modulator (3-1) is connected with a first DC bias power supply (11), and the second MZM modulator (3-2) The input end of the polarized light beam combiner (3-4) is connected with a second DC bias power supply (12), and the output end of the polarized light beam combiner (3-4) is connected with a fiber amplifier (13); The wired end includes an optical filter (14), the optical filter (14) is connected to the output end of the optical fiber amplifier (13), and the output end of the optical filter (14) is connected with a first photodetector ( 15) and a second photodetector (16), the output of the first photodetector (15) is connected with a first power amplifier (17), and the output of the first power amplifier (17) is connected with a transmitter an antenna (18), the output end of the second photodetector (16) is connected with a second power amplifier (19), and the output end of the second power amplifier (19) is connected with a first signal processor (20) ; The mobile terminal comprises a receiving antenna (21) for receiving wireless signals transmitted by a transmitting antenna (18), an output end of the receiving antenna (21) is connected with a third power amplifier (22), the third power amplifier The output terminal of (22) is connected with a second signal processor (23). 2 . The signal generation and transmission system based on polarization multiplexing dual MZM modulators according to claim 1 , wherein the fiber amplifier ( 13 ) is a polarization-maintaining erbium-doped fiber amplifier. 3 . 3. The signal generation and transmission system based on polarization multiplexing dual MZM modulators according to claim 1, characterized in that: the polarization beam splitter (3-3) and the first MZM modulator (3-1) between the polarization beam splitter (3-3) and the second MZM modulator (3-2), and between the first MZM modulator (3-1) and the polarization beam combiner (3-4) ) and between the second MZM modulator (3-2) and the polarization beam combiner (3-4) are connected by polarization-maintaining single-mode fibers. 4. The signal generation and transmission system based on polarization multiplexing dual MZM modulators according to claim 1, characterized in that: between the distributed feedback laser (1) and the polarization controller (6), the polarization controller (6) between the polarization beam splitter (3-3), between the polarization beam combiner (3-4) and the optical fiber amplifier (13), and between the optical fiber amplifier (13) and the optical filter (14) ) are connected by single-mode fiber. 5 . The signal generation and transmission system based on polarization multiplexing dual MZM modulators according to claim 1 , wherein the transmitting antenna ( 18 ) and the receiving antenna ( 21 ) are both Cassegrain antennas. 6 . 6. A method for signal generation and transmission utilizing the system according to claim 1, characterized in that: the method comprises the following steps: Step 1. The distributed feedback laser (1) _emits a coherent and continuous light source signal with a frequency fc, and after the polarization control of the optical signal is performed by the polarization controller (6), the optical signal is incident on the polarization multiplexing modulator (3). )middle; Step 2: The polarization beam splitter (3-3) in the polarization multiplexing modulator (3) separates the polarization state of the optical signal, and the separated two-path optical signals are respectively incident on the first MZM modulator (3). -1) and the second MZM modulator (3-2), the first DC bias power supply (11) DC biases the first MZM modulator (3-1) at the minimum transmission point, and the first DC bias power supply (11) Two DC bias power supplies (12) DC bias the second MZM modulator (3-2) at the quadrature point; Step 3: The first code type converter (4) converts the wireless data signal to be transmitted into a baseband electrical signal, and the baseband electrical signal is transmitted to the mixer (8) through a high-frequency coaxial cable; at the same time, the The local oscillator (2) generates a sine or cosine radio frequency signal with a frequency of f _s . The radio frequency signal is acted by a frequency multiplier (7), and the radio frequency signal is boosted by an integer multiple to become nf _s , and then transmitted to a high frequency coaxial cable. In the mixer (8), the frequency is mixed with the baseband electrical signal to obtain the radio frequency electrical signal; Step 4: The first radio frequency amplifier (9) amplifies the radio frequency electrical signal, and the amplified radio frequency electrical signal drives the first MZM modulator (3-1), and the first MZM modulator (3-1) amplifies the The resulting radio frequency electrical signal is subjected to carrier suppression to generate an optical millimeter-wave signal for transmitting wireless signals, and the optical millimeter-wave signal is transmitted to the polarized optical beam combiner (3-4); Step 5. The second code type converter (5) converts the wired data signal to be transmitted into a baseband electrical signal, and the baseband electrical signal is transmitted to the second radio frequency amplifier (10) through a high-frequency coaxial cable for amplification, and the amplification is performed. The latter baseband electrical signal directly drives the second MZM modulator (3-2), generates an optical carrier signal, and transmits it to the polarized light beam combiner (3-4); Step 6: The polarized optical beam combiner (3-4) couples the optical millimeter wave signal and the optical carrier signal into the same optical fiber, and the coupled optical signal is amplified by the optical fiber amplifier (13), and then transmitted to the optical filter ( 14) in; Step 7: The optical filter (14) at the wired end separates the coupled optical signals carrying different data, wherein the separated optical millimeter-wave signal is incident on the first photodetector (15) to generate an electrical millimeter-wave signal , the electric millimeter-wave signal is amplified by the first power amplifier (17), and then converted into a wireless electric millimeter-wave signal by the transmitting antenna (18), and sent to the space; at the same time, the separated optical carrier signal passes through the second photoelectric detection in turn After the device (16) and the second power amplifier (19), signal processing is performed by the first signal processor (20) to recover the wired data signal; Step 8. The receiving antenna (21) of the mobile terminal receives the wireless electric millimeter wave signal in the space, and the received electric millimeter wave signal is amplified by the third power amplifier (22), and then passed through the second signal processor (23). Perform signal processing to recover wireless data signals.

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