CN101702785B - Multi-wavelength passive optical network system, wavelength reusing method and optical network unit - Google Patents

Abstract

The present invention provides a multi-wavelength passive optical network system, a wavelength reuse method, and an optical network unit. The system includes: an optical line terminal, a wavelength division multiplexing module, and one or more optical network units. The optical line terminal is used for For sending multi-wavelength downlink signals and receiving uplink signals sent by the optical network unit; the optical network unit includes: a first optical branching module, which is used to split the downlink signals of predetermined wavelengths among the multi-wavelength downlink signals sent by the optical line terminal into the first road and the second road; the downlink signal receiving module is used to receive the downlink signal of the first road; the uplink signal modulation module is used to use the downlink signal of the second road as the modulated light source of the radio frequency uplink service signal of the optical network unit, for the optical network The uplink signal of the unit is modulated, and the modulated uplink radio frequency optical signal is sent to the optical line terminal. By using the technical solution, only the optical line terminal can provide the optical signal source of the whole system, and no light source needs to be configured on the optical network unit side.

Description

Multi-wavelength passive optical network system, wavelength reuse method and optical network unit

technical field

The invention relates to the technical field of passive optical networks, in particular to a multi-wavelength passive optical network system, a wavelength reuse method and an optical network unit.

Background technique

At present, the line rate of the broadband access network has reached the order of Gbit/s (Gbit/s), but the demand for bandwidth and the number of users are still increasing. Traditional Time-Division Multiplexing Passive Optical Network (TDM-PON) based on Time-Division Multiplexing Passive Optical Network (TDM-PON) is difficult to meet the ever-increasing bandwidth demand because the bandwidth is shared by a large number of users with a time-division multiplexing mechanism. In addition, the optical power budget allowed by the TDM-PON system is limited, which limits the branching capability and effective coverage of PON, that is, the number of Optical Network Units (Optical Network Unit, ONU) and the distance between them and the Optical Line Terminal (OLT). distance between. In contrast, the multi-wavelength passive optical network (Wavelength Division Multiplexing Passive Optical Network, WDM-PON) doubles the network bandwidth through multi-wavelength technology, has the advantages of high speed and easy upgrade, and is considered an optical access network. Ideal solution for upgrading and expanding capacity.

The access network is very sensitive to cost, so the proposed WDM-PON solution has outstanding problems such as high cost and complicated wavelength configuration mechanism. For example, the proposed WDM-PON solution needs to configure light source modules with corresponding wavelengths for each ONU. That is to say, in the implementation of the entire network system, light source modules with different wavelengths need to be configured for a large number of ONUs. This not only increases the cost, but also is not conducive to large-scale implementation and maintenance of system deployment. In addition, for the OLT, it is impossible to flexibly manage and configure the wavelengths of the entire network system, resulting in low utilization of network wavelength resources, and it is also not conducive to network optimization.

Contents of the invention

The purpose of the present invention is to provide a multi-wavelength passive optical network system capable of realizing wavelength reuse, a method for realizing wavelength reuse and an optical network unit, so as to solve the problem of the need for each ONU in the multi-wavelength passive optical network structure of the prior art. Configuring light source modules with corresponding wavelengths leads to technical problems such as increased costs and low utilization of network wavelength resources.

In order to achieve the above object, the present invention provides a multi-wavelength passive optical network system, including: an optical line terminal, a wavelength division multiplexing module, and one or more optical network units, characterized in that,

The optical line terminal is used to send multi-wavelength downlink signals and receive uplink radio frequency optical signals sent by the optical network unit;

The wavelength division multiplexing module is connected to the optical line terminal and the optical network units, and is used to decompose the multi-wavelength downlink signal sent by the optical line terminal into individual signals corresponding to each optical network unit. The single-wavelength downlink signal is sent to the corresponding optical network unit, and the single-wavelength uplink radio frequency optical signal from each optical network unit is combined and sent to the optical line terminal;

Each of the optical network units includes:

A first optical branching module, configured to divide the downlink signal of a predetermined wavelength among the multi-wavelength downlink signals sent by the optical line terminal into a first path and a second path;

a downlink signal receiving module, configured to receive the first downlink signal;

An uplink signal modulation module, configured to use the second downlink signal as a modulation light source for the radio frequency uplink service signal of the optical network unit to which the uplink signal modulation module belongs, modulate the radio frequency uplink service signal, and modulate the obtained The uplink radio frequency optical signal is sent to the wavelength division multiplexing module through the first optical branching module, and is sent to the optical line terminal by the wavelength division multiplexing module.

Preferably, in the multi-wavelength passive optical network system, each optical network unit further includes:

An electrical domain processing module, configured to obtain two same-frequency radio frequency uplink service signals with a predetermined phase difference and carrying uplink service data: a third radio frequency uplink service signal and a fourth radio frequency uplink service signal;

The uplink signal modulation module is further configured to divide the downlink signal of the second path into a fifth path and a sixth path, and use the downlink signal of the fifth path and the sixth path as the third path and the sixth path respectively. Modulating light sources for four radio frequency uplink service signals respectively modulate the third and fourth radio frequency uplink service signals, obtain two uplink radio frequency optical signals with a predetermined phase difference after modulation, and modulate the two channels to obtain The uplink radio frequency optical signal is coupled, and the coupled uplink radio frequency optical signal is sent to the optical line terminal.

Preferably, the multi-wavelength passive optical network system, wherein the uplink signal modulation module includes:

The second optical branching module, including a third branch and a fourth branch, is used to divide the second downlink signal into uniform fifth and sixth paths in the downlink direction, and the fifth path signal passes through the third Branch transmission, the sixth signal is transmitted through the fourth branch;

The first reflective semiconductor optical amplifier is connected to the third branch of the second optical branching module and the electrical domain processing module, and is used to use the downlink signal of the fifth path as a modulated light source for the third path Modulating the radio frequency uplink service signal, and outputting the modulated first uplink radio frequency optical signal;

The second reflective semiconductor optical amplifier is connected to the fourth branch of the second optical branch module and the circuit domain module, and is used to use the downlink signal of the sixth path as a modulation light source to transmit the radio frequency of the fourth path modulate the uplink service signal, and output the modulated second uplink radio frequency optical signal;

The second optical branching module is further configured to couple the first uplink radio frequency optical signal and the second uplink radio frequency optical signal, and send the coupled uplink radio frequency optical signal to the Described optical line terminal.

Preferably, in the multi-wavelength passive optical network system, the uplink signal modulation module is: a waveguide Michelson interferometer supplemented with a reflective semiconductor optical amplifier, and the first and second reflective semiconductor optical The amplifiers are respectively located at the upper and lower arms of the waveguide Michelson interferometer.

Preferably, in the multi-wavelength passive optical network system, when the uplink service signal of the optical network unit is a baseband uplink service signal, the electrical domain processing module includes:

The radio frequency signal source is used to generate two radio frequency carrier signals of the same frequency and phase;

The first phase shift module is connected to the radio frequency signal source and is used to adjust the phase difference of the two radio frequency carrier signals to obtain a first radio frequency carrier signal and a second radio frequency carrier signal with a predetermined phase difference;

a modulation module, configured to divide the baseband uplink service signal into two paths, and modulate the two paths of baseband uplink service signal onto the first radio frequency carrier signal and the second radio frequency carrier signal respectively, so as to obtain the baseband uplink service signal carrying the baseband The third radio frequency uplink service signal and the fourth radio frequency uplink service signal of service signal data.

Preferably, in the multi-wavelength passive optical network system, the phase difference between the third radio frequency uplink service signal and the fourth radio frequency uplink service signal is: 0 degrees, 90 degrees or 180 degrees.

Preferably, the multi-wavelength passive optical network system, wherein the uplink signal modulation module further includes:

The second phase shift module is arranged on the third branch or the fourth branch of the second optical branching module, and is used to adjust the phase difference between the first uplink radio frequency optical signal and the second uplink radio frequency optical signal to a predetermined value .

Preferably, in the multi-wavelength passive optical network system, when the uplink service signal of the optical network unit is a radio frequency uplink service signal, the electrical domain processing module includes:

The third phase shifting module is configured to adjust the phase of the radio frequency uplink service signal divided into two channels to obtain the third radio frequency uplink service signal and the fourth radio frequency uplink service signal with a predetermined phase difference.

Preferably, in the multi-wavelength passive optical network system, each of the optical network units further includes:

An optical signal isolator, connected to the first optical branch module and the downlink signal receiving module, is used to directly pass the first downlink signal to the downlink signal receiving module, and prevent the downlink signal receiving module from reflecting back light signal.

Preferably, in the multi-wavelength passive optical network system, the multi-wavelength downlink signal sent by the optical line terminal sending module is: a multi-wavelength downlink signal formed by performing direct intensity modulation on multiple single-wavelength downlink signals.

On the other hand, a method for realizing wavelength reuse in a multi-wavelength passive optical network system is provided, which includes:

Step A, the optical network unit divides the downlink signal of a predetermined wavelength sent by the optical line terminal into a first path and a second path;

Step B, the optical network unit receives the first downlink signal, and uses the second downlink signal as a modulation light source for modulating the radio frequency uplink service signal, and obtains the uplink radio frequency after modulating the radio frequency uplink service signal an optical signal, and send the uplink radio frequency optical signal to the optical line terminal.

Preferably, said method, wherein said step B comprises:

Step B1, obtaining two same-frequency radio frequency uplink service signals with a predetermined phase difference and carrying uplink service signal data: a third radio frequency uplink service signal and a fourth radio frequency uplink service signal;

Step B2, dividing the second downlink signal into fifth and sixth downlink signals, and using the fifth and sixth downlink signals as the modulation of the third and fourth radio frequency uplink service signals respectively The light source modulates the third and fourth radio frequency uplink service signals respectively, obtains two uplink radio frequency optical signals with a predetermined phase difference after modulation, and converts the two modulated uplink radio signals with a predetermined phase difference The radio frequency optical signal is coupled, and the coupled uplink radio frequency optical signal is sent to the optical line terminal.

Preferably, the method, wherein, when the uplink service signal of the optical network unit is a baseband uplink service signal, the step B1 includes:

Use the RF signal source to generate two RF carrier signals with the same frequency and phase;

Using the first phase shift module to adjust the phase difference of the two radio frequency carrier signals to obtain a first radio frequency carrier signal and a second radio frequency carrier signal with a predetermined phase difference;

Divide the baseband uplink service signal sent by the optical network unit into two paths, modulate the two paths of baseband uplink service signal onto the first radio frequency carrier signal and the second radio frequency carrier signal respectively, and obtain the baseband uplink service carrying the The third radio frequency uplink service signal and the fourth radio frequency uplink service signal of signal data.

Preferably, the method, wherein, when the uplink service signal of the optical network unit is a radio frequency uplink service signal, the step B1 includes:

dividing the radio frequency uplink service signal into two paths;

Using the third phase shift module to adjust the phase difference of the two radio frequency uplink service signals to obtain the third radio frequency uplink service signal and the fourth radio frequency uplink service signal with a predetermined phase difference.

Preferably, the method, wherein the optical network unit implements the above step B through an uplink signal modulation module, and the uplink signal modulation module includes:

The second optical branching module includes a third branch and a fourth branch, configured to divide the second downlink signal into a fifth path and a sixth path, the fifth path signal is transmitted through the third branch, and the The sixth signal is transmitted through the fourth branch;

The first reflective semiconductor optical amplifier is connected to the third branch of the second optical branch module, and is used to modulate the third radio frequency uplink service signal by using the fifth downlink signal as a modulation light source, and output the modulated first uplink radio frequency optical signal;

The second reflective semiconductor optical amplifier is connected to the fourth branch of the second optical branch module, and is used to modulate the fourth radio frequency uplink service signal by using the sixth downlink signal as a modulation light source, and output the modulated second uplink radio frequency optical signal;

The second optical branching module is further configured to couple the first uplink radio frequency optical signal and the second uplink radio frequency optical signal, and send the coupled uplink radio frequency optical signal to the optical line terminal.

In yet another aspect, an optical network unit is provided, including:

The first optical branching module is configured to divide the downlink signal of a predetermined wavelength among the multi-wavelength downlink signals sent by the optical line terminal into a first path and a second path;

a downlink signal receiving module, configured to receive the first downlink signal;

An uplink signal modulation module, configured to use the second downlink signal as a modulation light source for the radio frequency uplink service signal of the optical network unit to which the uplink signal modulation module belongs, modulate the radio frequency uplink service signal, and modulate the obtained The uplink radio frequency optical signal is sent to the optical line terminal.

Preferably, the optical network unit further includes:

An electrical domain processing module, configured to obtain two same-frequency radio frequency uplink service signals with a predetermined phase difference and carrying uplink service data: a third radio frequency uplink service signal and a fourth radio frequency uplink service signal;

The uplink signal modulation module is further configured to divide the downlink signal of the second path into a fifth path and a sixth path, and use the downlink signal of the fifth path and the sixth path as the third path and the sixth path respectively. Modulating light sources for four radio frequency uplink service signals respectively modulate the third and fourth radio frequency uplink service signals to obtain two modulated uplink radio frequency optical signals with a predetermined phase difference, and convert the modulated uplink radio frequency optical signals with a predetermined phase difference Coupling the modulated uplink radio frequency optical signals of the two channels, and sending the coupled uplink radio frequency optical signals to the optical line terminal.

Preferably, the optical network unit, wherein the uplink signal modulation module includes:

The second optical branching module, including a third branch and a fourth branch, is used to divide the second downlink signal into uniform fifth and sixth paths in the downlink direction, and the fifth path signal passes through the third Branch transmission, the sixth signal is transmitted through the fourth branch;

The first reflective semiconductor optical amplifier is connected to the third branch of the second optical branching module and the electrical domain processing module, and is used to use the downlink signal of the fifth path as a modulated light source for the third path Modulating the radio frequency uplink service signal, and outputting the modulated first uplink radio frequency optical signal;

The second reflective semiconductor optical amplifier is connected to the fourth branch of the second optical branch module and the circuit domain module, and is used to use the downlink signal of the sixth path as a modulation light source to transmit the radio frequency of the fourth path modulate the uplink service signal, and output the modulated second uplink radio frequency optical signal;

The second optical branching module is further configured to couple the first uplink radio frequency optical signal and the second uplink radio frequency optical signal, and send the coupled uplink radio frequency optical signal to the Described optical line terminal.

Preferably, the optical network unit, wherein the uplink signal modulation module is: a waveguide Michelson interferometer supplemented with a reflective semiconductor optical amplifier, and the first and second reflective semiconductor optical amplifiers are respectively located in the The upper and lower arms of the waveguide-type Michelson interferometer.

Preferably, in the optical network unit, when the uplink service signal of the optical network unit is a baseband uplink service signal, the electrical domain processing module includes:

The radio frequency signal source is used to generate two radio frequency carrier signals of the same frequency and phase;

The first phase shift module is connected to the radio frequency signal source and is used to adjust the phase difference of the two radio frequency carrier signals to obtain a first radio frequency carrier signal and a second radio frequency carrier signal with a predetermined phase difference;

A modulating module, configured to divide the baseband uplink service signal into two paths, and modulate the two paths of baseband uplink signal to the first radio frequency carrier signal and the second radio frequency carrier signal respectively, so as to obtain the baseband uplink service carrying The third radio frequency uplink service signal and the fourth radio frequency uplink service signal of the signal data.

Preferably, in the optical network unit, the phase difference between the third radio frequency uplink service signal and the fourth radio frequency uplink service signal is: 0 degrees, 90 degrees or 180 degrees.

One of the above technical solutions has the following technical effects:

By adopting the uplink signal modulation module at the ONU, only the optical line terminal OLT can provide the optical signal source of the whole system, and the downlink optical signal can be used as the modulation light source of the radio frequency uplink service signal on the ONU side. The ONU side reuses and loads the upstream signal, and then sends it back to the OLT. In this way, the ONU side uses the wavelength assigned by the OLT, and does not need to configure a light source module, thereby saving costs and realizing the colorless ONU, that is, the ONU has a wavelength adaptability;

Furthermore, since the downlink baseband signal and the uplink radio frequency optical signal with a certain frequency shift are staggered in the frequency domain, single-fiber bidirectional transmission can be performed, thereby truly realizing the full-duplex operation of the entire multi-wavelength passive optical network.

Description of drawings

FIG. 1 is a schematic structural diagram of a multi-wavelength passive optical network system according to an embodiment of the present invention;

2 is a schematic structural diagram of a multi-wavelength passive optical network system according to another embodiment of the present invention;

3 is a schematic structural diagram of a multi-wavelength passive optical network system according to another embodiment of the present invention;

FIG. 4 is a schematic structural diagram of an optical network unit according to an embodiment of the present invention;

5 is a schematic structural diagram of a multi-wavelength passive optical network system according to another embodiment of the present invention;

Fig. 6 is the spectrum diagram outputted by the uplink signal of the radio frequency 5 GHz through the RSOA-MI structure in the embodiment shown in Fig. 4 of the present invention;

Fig. 7 is the spectrum diagram outputted by the uplink signal of the radio frequency 32 GHz through the RSOA-MI structure in the embodiment shown in Fig. 4 of the present invention;

8 is a schematic structural diagram of cascading multiple passive optical network PON modules of an optical line terminal in an embodiment of the present invention;

FIG. 9 is a schematic flowchart of a method for implementing wavelength reuse in a multi-wavelength passive optical network system according to an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a schematic structural diagram of a multi-wavelength passive optical network system according to an embodiment of the present invention. As shown in Fig. 1, the multi-wavelength passive optical network system of the embodiment of the present invention includes: an optical line terminal 101, a wavelength division multiplexing module 102, and one or more optical network units 103, wherein,

The optical line terminal is used to send multi-wavelength downlink signals and receive uplink radio frequency optical signals sent by the optical network unit;

The wavelength division multiplexing module is connected to the optical line terminal and the optical network units, and is used to decompose the multi-wavelength downlink signal sent by the optical line terminal into individual signals corresponding to each optical network unit. The single-wavelength downlink signal is sent to the corresponding optical network unit, and the single-wavelength uplink radio frequency optical signal from each optical network unit is combined and sent to the optical line terminal;

Each of the optical network units includes: a first optical branching module 104, configured to divide the downlink signal of a predetermined wavelength among the multi-wavelength downlink signals sent by the optical line terminal into a first path and a second path; the downlink signal The receiving module 105 is used to receive the first downlink signal, and obtain the downlink signal data in the downlink signal, and obtain the target data sent by the OLT to the user; the uplink signal modulation module 106 is used to convert the second way The downlink signal is used as a modulation light source for the radio frequency uplink service signal of the optical network unit to which the uplink signal modulation module belongs, modulates the radio frequency uplink service signal, and sends the modulated uplink radio frequency optical signal to the wave channel through the first optical branch module Division multiplexing module, and then sent to the optical line terminal by the wavelength division multiplexing module.

In the technical solution of the embodiment of the present invention, by adopting the upstream signal modulation module at the optical network unit ONU, only the optical line terminal OLT can provide the optical signal source of the entire system, and use the downstream optical signal as the modulation of the radio frequency upstream service signal on the ONU side The light source is reused when the downlink optical signal passes through the ONU side and loaded with the uplink service signal, and then sent back to the OLT. In this way, the wavelength is assigned by the OLT, and the ONU side does not need to configure a light source module, thus realizing the colorless ONU, that is, ONU has wavelength adaptability.

In the embodiment of the present invention, which specific optical network unit corresponds to which wavelength may be pre-assigned by the OLT.

Preferably, in the multi-wavelength passive optical network system, each optical network unit further includes: an electrical domain processing module, configured to obtain two same-frequency radio frequency uplink channels with a predetermined phase difference and carrying uplink service data Service signals: the third radio frequency uplink service signal and the fourth radio frequency uplink service signal; the uplink signal modulation module is further used to divide the second downlink signal into fifth and sixth channels, and divide the The fifth and sixth downlink signals are respectively used as modulation light sources for the third and fourth radio frequency uplink service signals, and the third and fourth radio frequency uplink service signals are respectively modulated to obtain two channels The modulated uplink radio frequency optical signal with a predetermined phase difference is coupled to the two modulated uplink radio frequency optical signals, and the coupled uplink radio frequency optical signal is sent to the optical line terminal.

Preferably, the multi-wavelength passive optical network system, wherein, the uplink signal modulation module includes: a second optical branch module, including a third branch and a fourth branch, for splitting the second optical branch in the downlink direction The downlink signal is divided into a uniform fifth path and a sixth path, the fifth path signal is transmitted through the third branch, and the sixth path signal is transmitted through the fourth branch; the first reflective semiconductor optical amplifier (RSOA , Reflective Semiconductor Optical Amplifier), connected to the third branch of the second optical branch module and the electrical domain processing module, for using the fifth path downlink signal as a modulation light source to the third path radio frequency The uplink service signal is modulated, and the modulated first uplink radio frequency signal is output; the second reflective semiconductor optical amplifier is connected with the fourth branch of the second optical branch module and the circuit domain module, and is used for using the The sixth downlink signal is used as a modulation light source to modulate the fourth radio frequency uplink service signal, and output the modulated second uplink radio frequency optical signal; the second optical branch module is further used to transfer the first An uplink radio frequency optical signal is coupled with a second uplink radio frequency optical signal, and the coupled uplink radio frequency optical signal is sent to the optical line terminal through the first optical branching module.

FIG. 2 is a schematic structural diagram of a multi-wavelength passive optical network system according to another embodiment of the present invention. As shown in FIG. 2 , the multi-wavelength passive optical network system of this embodiment of the present invention includes: an optical line terminal OLT 201 , a waveguide array grating 202 and n optical network units ONU 203 , where n is an integer. Exemplarily, the number n of ONUs may generally be 16, 32, 64 and so on. As shown in Figure 2, the OLT sends downlink signals of n wavelengths from λ ₁ to λ _n to n ONUs respectively.

In this embodiment, the optical signal source of the entire system is provided by the OLT, and the modulation part of the upstream signal including the RSOA, that is, the upstream signal modulation module is used at the ONU to replace the light source with the RSOA module as a modulator. When the downstream optical signal passes through the ONU side It is reflected and reused and loaded with radio frequency upstream signals, that is, radio frequency upstream business signals to form upstream radio frequency optical signals, and then sent back to the OLT, so the ONU is colorless, that is, wavelength adaptive. The downlink signal is a baseband signal, and by adjusting the phase difference between the first uplink radio frequency optical signal and the second uplink radio frequency optical signal before coupling, special modulation formats such as radio frequency single sideband SSB, double sideband DSB or suppressed optical carrier OCS can be realized Uplink signal, so that while realizing full duplex, it can effectively suppress unfavorable factors such as back Rayleigh scattering and fiber dispersion.

In this example, the wavelength division multiplexing module is a wavelength division multiplexer, and a wavelength division multiplexer is also called a WDM multiplexer/demultiplexer, which can be realized by using an arrayed waveguide grating (AWG) and other devices, and adopts a 1×n port structure , wherein n is an integer, for example, n is 16, 32 or 64, etc., and its value is equal to the number of ONUs. The wavelength division multiplexer decomposes the downstream multi-wavelength optical signal into individual single-wavelength signals corresponding to each ONU, and multiplexes the single-wavelength upstream radio frequency optical signal from each ONU into one multi-wavelength upstream radio frequency optical signal corresponding to the OLT.

FIG. 3 is a schematic structural diagram of a multi-wavelength passive optical network system according to another embodiment of the present invention. FIG. 4 is a schematic structural diagram of an optical network unit according to an embodiment of the present invention. As shown in Fig. 3, in this embodiment, the optical line terminal 6 includes at least one optical line terminal transmitting module TX1 61 and the optical line terminal receiving module RX163; wherein, the optical line terminal transmitting module 61 is used for direct modulation of the laser on the downlink signal , so that the downlink signal sent by the optical line terminal transmitting module is a baseband signal; the optical line terminal receiving module 63 is used to receive the uplink signal. In the technical solution of the present invention, it is used to receive the uplink radio frequency signal sent by the optical network terminal. The signal is demodulated and subjected to predetermined processing.

In this example, in the optical line terminal 6, the downlink signal is obtained by directly modulating the laser in the TX1 61, and injected into the optical fiber 5 through the circulator 62 for downlink transmission. And from the optical network unit, the uplink signal output through the optical fiber 5 enters the RX1 63 after passing through the circulator 62.

The remote node 4 is mainly a wavelength division multiplexer, which can be realized by using an existing arrayed waveguide grating (AWG). It is mainly used to multiplex or combine the upstream signals from each ONU in the upstream direction, and to split the downstream signals from the OLT in the downstream direction.

As shown in FIG. 3 and FIG. 4 , the optical network unit 1 includes: a 1×2 optical splitter 3 , a receiving part 2 for downlink signals, and a modulation part 1 for uplink signals. In this embodiment, the modulation part 1 of the uplink signal includes: a waveguide Michelson interferometer RSOA-MI supplemented with a reflective semiconductor optical amplifier RSOA. In this example, RSOA-MI includes: 1×2 optical splitter 3 and two RSOAs 15 and 16 .

As shown in Figure 3, the arrow indicates the transmission direction of the signal, the thick line describes the optical path, and the thin line describes the transmission channel of the electrical domain signal. The optical signals for downlink transmission are all represented by "d ^* " in sequence according to the direction of optical downlink, and the optical signals for uplink transmission are all represented by "u ^* " in sequence according to the direction of optical uplink. As shown in FIG. 3 , specifically, the downlink signal includes "d1" to "d5"; the uplink signal includes "u1" to "u5".

The process of implementing wavelength reuse in the multi-wavelength passive optical network system of this embodiment is described below:

In the downstream direction:

1×2 optical splitter 3, which divides the pre-designated single-wavelength downlink optical signal d1 corresponding to its own optical network unit into two paths of 1:1: one path d2 enters the receiving part 2 of the downlink signal, and passes through the optical signal The isolator 21 enters the downlink signal receiving module 22 of the ONU; the other path d3 enters the modulation part 1 of the uplink signal. In the modulation part 1 of the uplink signal, the 1×2 optical splitter 18 divides the incoming optical signal d3 into two uniform beams d4 and d5, which respectively enter the RSOA 15 and RSOA 16 of the upper and lower arms of the RSOA-MI. It has the characteristics of fast saturation and slow recovery of the gain, and has an amplitude clamping effect on the input optical signal. The amplitude of the optical signal reflected by the RSOA has little change and is used as a modulated light source for the uplink service signal. Exemplarily, the optical splitter 18 is a waveguide type optical splitter.

In the embodiment of the present invention, the uplink service data can be divided into two situations, and the uplink service data can have the following two situations: (1) when the uplink service signal of the optical network unit is a baseband uplink service signal, the baseband uplink service signal first passes through The electrical domain processing module of the ONU modulates to the radio frequency, and then divides into two radio frequency uplink service signals with an appropriate phase difference, which are respectively used as two RSOA electrical modulation signals; (2) The uplink service signal of the optical network unit is from the wireless service interface When entering the radio frequency uplink service signal of the AP, the uplink radio frequency uplink service signal is divided into two paths and an appropriate phase difference is added to be used as the electrical modulation signal of the RSOA. The downlink optical signal input to the RSOA is used as the modulation light source, the electrical modulation signal input to the RSOA is loaded on the downlink signal input to the RSOA, and the two downlink optical signals loaded with the electrical modulation signal are reflected back to the optical splitter 18, and passed through the optical splitter 18. After coupling, output the coupled uplink radio frequency optical signal. Wherein, the above coupling is to combine the optical power of the two downlink optical signals loaded with the electrical modulation signal reflected back by the above two RSOAs.

Fig. 3 shows an embodiment when the uplink service signal is a baseband uplink service signal. As shown in Figure 3, in the uplink direction:

The radio frequency signal source 11 generates a radio frequency carrier signal with a predetermined frequency, exemplarily generating a radio frequency carrier signal with a frequency fs. In this example, the RF carrier signal generated by the RF signal source is divided into two RF carrier signals with the same frequency and phase, and the phase difference between the above two RF carrier signals is adjusted by the first phase shift module to obtain the second RF carrier signal with a predetermined phase difference. A radio frequency carrier signal and a second radio frequency carrier signal. In a specific implementation, the first phase shift module achieves the effect of adjusting the phase difference of two radio frequency signals by adjusting the phase of one radio frequency carrier signal.

Divide the baseband uplink service signals into two even paths, and modulate the uplink service data in the two paths of baseband uplink service signals to the above two paths of radio frequency carrier signals with the same frequency and a predetermined phase difference, and convert the obtained two paths of radio frequency carrier signals into , that is, the first radio frequency carrier signal and the second radio frequency carrier signal, as the electrical modulation signals of the two RSOAs, modulate the downlink signal used as the light source at this time, and realize radio frequency subcarrier modulation. In specific implementation, the modulation module is used to modulate the data of the baseband uplink service signal onto the radio frequency carrier. Exemplarily, the baseband uplink signal is modulated onto the radio frequency carrier signal through the multipliers 13 and 14 shown in FIG. 3 respectively.

At the optical splitter 18 , after coupling the two beams of light u1 and u2 reflected back by the two RSOAs, they are transmitted back to the optical splitter 3 to continue uplink transmission. Wherein, the two beams of light u1 and u2 are the first uplink radio frequency optical signal and the second uplink radio frequency optical signal loaded with the electrical modulation signal. Wherein, the phase difference of the two radio frequency carrier signals can be adjusted by the second phase shift module 17, so that the light u1 and u2 input to the optical splitter 18 have a predetermined phase difference. Usually, after the phase difference between the two radio frequency carriers is set by the first phase shift module, the second phase shift module 17 plays the role of fine-tuning, so that the phase difference between the light u1 and u2 reaches a predetermined value, thus, through the optical branch The uplink radio frequency optical signal coupled out by the device can meet predetermined requirements, for example, the coupled uplink radio frequency optical signal becomes an SSB signal. In a specific implementation, the above-mentioned phase shift module may be implemented as a phase shifter.

In this embodiment, the key components are reflective semiconductor optical amplifiers RSOA15 and RSOA16. In a specific implementation, a common commercial RSOA can be used, and there is no additional parameter value limitation. The downlink wavelength is reused, and the uplink data is subjected to phase-shift correlation processing and then modulated by two RSOAs respectively, so as to realize uplink optical signals with different modulation modes.

As shown in FIG. 3 , in this embodiment, the electrical domain processing module included in the optical network unit includes: a radio frequency signal source 11 , a first phase shift module 12 , a first multiplier 13 , and a second multiplier 14 . The electrical domain processing module modulates the baseband uplink service signal onto the radio frequency carrier, and outputs the radio frequency carrier carrying the uplink signal data, that is, the radio frequency uplink service signal as the electrical modulation signal input to the RSOA. In the subsequent processing, the downstream signal reflected by RSOA is used as the modulation light source of the upstream signal to realize the reuse of the downstream signal and the reflection of the upstream signal when the ONU does not have an optical transmission module, thereby realizing the wavelength self-adaptation of the ONU. In this example, the function of the electrical domain processing module is to load the baseband uplink service signal on the radio frequency carrier signal with a predetermined phase difference to form a radio frequency uplink service signal that can be used as a different RSOA electrical modulation signal.

Further, by adjusting the phase shift value of the above-mentioned first phase shift module and/or the second phase shift module, the uplink signal can be flexibly modulated into a radio frequency unilateral with a certain frequency shift while realizing the wavelength self-adaptation of the ONU. band, double sideband or suppressed optical carrier signals. Exemplarily, when the phase difference between the two electrical modulation signals input to the two RSOAs is 90 degrees, the uplink radio frequency optical signal sent by the optical network unit to the optical line terminal is a radio frequency single sideband signal modulated on a predetermined wavelength, When the downlink signal output by the optical line terminal is a baseband signal with a wavelength of _λ0 , the uplink signal output to the optical line terminal after modulation by RSOA-MI is a radio frequency single sideband signal with a certain frequency shift; When the phase difference is 180 degrees, the uplink signal is a suppressed optical carrier signal correspondingly modulated on a predetermined wavelength; when the phase difference between the two electrical domain signals is 0 degree, the uplink signal is a radio frequency double sideband signal correspondingly modulated on a predetermined wavelength. In summary, when the downlink signal is a baseband signal, the multi-wavelength passive optical network system of the embodiment of the present invention can simultaneously transmit uplink and downlink signals on a single fiber, so that while realizing full duplex, reverse Harmful factors such as Rayleigh scattering and fiber dispersion avoid the influence of reverse Rayleigh scattering and fiber dispersion, so that single-fiber bidirectional high-speed signal transmission with high quality can be realized at a lower cost.

FIG. 5 is a schematic structural diagram of a multi-wavelength passive optical network system according to another embodiment of the present invention. In this embodiment, the uplink service signal of the optical network unit is directly the radio frequency uplink service signal from the wireless service access point AP, and the radio frequency uplink service data is divided into two paths and added with an appropriate phase difference as an electrical modulation signal of the RSOA. As shown in Figure 5, the electrical domain processing module of this embodiment includes: a third phase shift module 19, which is used to adjust the phase of the uplink radio frequency signal divided into two transmissions, so as to obtain an input RSOA with a predetermined phase difference as an electrical modulation There are two radio frequency uplink signals of the signal, and the third and fourth radio frequency uplink signals.

Fig. 6 is the spectrum diagram of the output signal of the 5 GHz radio frequency uplink signal through the RSOA-MI structure when the phase difference of the electrical domain signal input to the RSOA is 90 degrees and the wavelength of the light source is 1490 nanometers in the embodiment shown in Fig. 4 of the present invention. It can be seen from FIG. 6 that the uplink radio frequency optical signal of 5 GHz output through the RSOA-MI structure is a radio frequency single sideband signal modulated at a wavelength of 1490 nanometers.

Fig. 7 is the spectrum diagram of the output signal of the 32 GHz radio frequency uplink signal through the RSOA-MI structure when the phase difference of the electrical domain signal input to the RSOA is 90 degrees and the wavelength of the light source is 1550 nanometers in the embodiment shown in Fig. 4 of the present invention. It can be seen from Fig. 7 that the uplink radio frequency optical signal of radio frequency 32 GHz output through the RSOA-MI structure is a radio frequency single sideband signal modulated at a wavelength of 1550 nanometers.

The embodiments shown in Fig. 3 and Fig. 4 show the situation that there is only one sending unit on the optical line terminal side and only corresponds to one optical network unit. In a specific implementation, one optical line terminal may correspond to multiple optical network units. Therefore, a plurality of optical transmission modules can be arranged in the optical line terminal, and a wavelength division multiplexing multiplexer and a demultiplexer are added to realize an optical network. Fig. 8 is a schematic structural diagram of cascading multiple passive optical network PON modules of an optical line terminal in an embodiment of the present invention. CO (central office) means the central office.

The embodiment of the invention also discloses a method for realizing wavelength reuse in a multi-wavelength passive optical network system. As shown in Figure 9, the method for implementing wavelength reuse in the multi-wavelength passive optical network system of the embodiment of the present invention includes:

Step 901, the optical network unit divides the downlink signal of a predetermined wavelength sent by the optical line terminal into a first path and a second path;

In this step, in specific implementation, the multi-wavelength signal sent by the optical line terminal is decomposed into multiple single-wavelength downlink signals according to the wavelength through a wavelength division multiplexing module such as AWG, and the multiple single-wavelength downlink signals correspond to different optical network units. ;

Step 902, the optical network unit receives the first downlink signal, uses the second downlink signal as a modulation light source for modulating the radio frequency uplink service signal, and obtains the uplink signal after modulating the radio frequency uplink service signal. radio frequency optical signal, and send the uplink radio frequency optical signal to the optical line terminal.

Preferably, said method, wherein said step B comprises:

Step B1, obtaining two same-frequency radio frequency uplink service signals with a predetermined phase difference and carrying uplink service signal data: a third radio frequency uplink service signal and a fourth radio frequency uplink service signal;

Step B2, dividing the second downlink signal into fifth and sixth downlink signals, and using the fifth and sixth downlink signals as the modulation of the third and fourth radio frequency uplink service signals respectively a light source, respectively modulating the third and fourth radio frequency uplink service signals to obtain two modulated uplink radio frequency optical signals with a predetermined phase difference; After the uplink radio frequency optical signal is coupled, the coupled uplink radio frequency optical signal is sent to the optical line terminal.

Preferably, the method, wherein, when the uplink service signal of the optical network unit is a baseband uplink service signal, the step B1 includes:

Use the RF signal source to generate two RF carrier signals with the same frequency and phase;

Using the first phase shift module to adjust the phase difference of the two radio frequency carrier signals to obtain a first radio frequency carrier signal and a second radio frequency carrier signal with a predetermined phase difference;

Divide the baseband uplink service signal sent by the optical network unit into two paths, modulate the two paths of baseband uplink service signal onto the first radio frequency carrier signal and the second radio frequency carrier signal respectively, and obtain the baseband uplink service carrying the The third radio frequency uplink service signal and the fourth radio frequency uplink service signal of signal data.

Preferably, the method, wherein, when the uplink service signal of the optical network unit is a radio frequency uplink service signal, the step B1 includes:

dividing the radio frequency uplink service signal into two paths;

Using the third phase shift module to adjust the phase difference of the two radio frequency uplink service signals to obtain the third radio frequency uplink service signal and the fourth radio frequency uplink service signal with a predetermined phase difference.

Preferably, the method, wherein the optical network unit implements the above step B through an uplink signal modulation module, and the uplink signal modulation module includes:

The second optical branching module includes a third branch and a fourth branch, configured to divide the second downlink signal into a fifth path and a sixth path, the fifth path signal is transmitted through the third branch, and the The sixth signal is transmitted through the fourth branch;

The first reflective semiconductor optical amplifier is connected to the third branch of the second optical branch module, and is used to modulate the third radio frequency uplink service signal by using the fifth downlink signal as a modulation light source, and output the modulated first uplink radio frequency optical signal;

The second reflective semiconductor optical amplifier is connected to the fourth branch of the second optical branch module, and is used to modulate the fourth radio frequency uplink service signal by using the sixth downlink signal as a modulation light source, and output the modulated second uplink radio frequency optical signal;

The second optical branching module is further configured to couple the first uplink radio frequency optical signal and the second uplink radio frequency optical signal, and send the coupled uplink radio frequency optical signal to the optical line terminal.

In combination with the multi-wavelength passive optical network system of the above-mentioned embodiments of the present invention, the method for realizing wavelength reuse in an embodiment of the present invention includes:

The multi-channel downlink signal is directly modulated at the multi-wavelength light source of the OLT, and the multi-wavelength modulated signal forms a multi-wavelength downlink signal;

The above multi-wavelength downlink signal is transmitted to the ONU through the trunk fiber, wavelength division multiplexer, and branch fiber, and is divided into two bundles by the optical splitter 3. One bundle is demodulated and restored by the receiving module as a downlink signal, and the other bundle enters the ONU. The modulation part of the uplink signal, namely RSOA-MI;

The modulation part of the upstream signal of the ONU uses an optical splitter to divide the optical signal into two even paths, and enters the RSOA of the upper and lower arms respectively. The RSOA has amplitude clamping on the input optical signal due to its fast gain saturation and slow recovery characteristics. Function, the amplitude of the optical signal reflected by the RSOA does not change much and is used as a modulated light source for the uplink signal;

In the ONU electrical domain processing module, the uplink data is modulated onto two orthogonal radio frequency carriers of the same frequency, and the obtained two radio frequency signals are used as the electrical modulation signals of two RSOAs, and the downlink signal used as the light source at this time is modulated . Adjusting the phase difference of two radio frequency carrier signals can make the uplink radio frequency optical signal obtained after coupling realize the special modulation format of SSB or OCS.

In the method of this embodiment, the downlink multi-wavelength baseband signal of the WDM-PON adopts direct intensity modulation for each channel; the uplink signal is a multi-wavelength subcarrier signal, and each channel signal is SSB modulated on a subcarrier of a certain wavelength Or OCS signal; therefore, the uplink and downlink signals can be transmitted simultaneously on a single fiber without being affected by back Rayleigh scattering. Here is an explanation of the subcarrier: there is a light source in the optical line terminal, and the light source provides multi-wavelength optical carriers. The radio frequency uplink signal is the signal formed by modulating the radio frequency carrier, which is modulated onto the optical signal by RSOA. At this time, in the radio frequency optical signal, the original radio frequency carrier becomes the subcarrier.

The electric field processing module inputs the electric field signals in the two RSOAs with the same frequency, and there is only a special phase difference. In this way, after the optical signals modulated by the reflection of the two RSOAs are coupled by the optical splitter 18, a relatively ideal special modulation effect can be produced. For example, when the two electrical domain signals input to the RSOA have a phase difference of 90°, after the remodulated optical signals output by the two RSOAs are coupled, optical single sideband SSB modulation can be realized. When the two electrical domain signals input to the RSOA have a phase difference of 180°, the optically suppressed carrier OCS modulation can be realized after the remodulated optical signals output by the two RSOAs are coupled.

Compared with the prior art, a technical solution of the present invention has the following advantages:

By reusing the downlink signal light transmitted by the OLT, these downlink optical signals are used as the modulation light source for the uplink signal, so that there is no need to configure a special light source for the uplink signal in the ONU, so that the configuration of all ONUs in the WDM-PON is unified. It is convenient for large-scale production and large-scale procurement, thereby reducing costs.

Further, in the technical solution of the embodiment of the present invention, the uplink and downlink optical signals share an optical carrier of the same wavelength, the downlink is a baseband signal, and the uplink is a radio frequency signal shifted by a certain frequency, which not only saves wavelength resources, but also overcomes the traditional single The disadvantage of being seriously affected by reverse Rayleigh scattering in fiber single-wavelength bidirectional WDM-PON;

Further, in the technical solution of the embodiment of the present invention, the ONU does not need to configure an uplink light source with a special wavelength, and the ONU has wavelength independence, that is, adaptability to wavelength, which facilitates the unified allocation and scheduling of wavelength resources by the OLT from the perspective of the entire network;

Further, the technical solutions of the embodiments of the present invention can flexibly implement uplink signals with special modulation formats such as SSB or OCS while realizing the wavelength self-adaptive capability of the ONU. The influence of radio frequency optical signal;

Further, in the ONU of the embodiment of the present invention, the passive optical device adopts a waveguide type device in links such as light splitting and modulation, and the active optical device is a compact RSOA device, and the overall structure is small in size, easy to integrate, and low in power consumption;

Further, the technical solutions of the embodiments of the present invention are applicable to two cases of symmetric and asymmetric uplink and downlink signal rates, and under low power conditions, downlink wavelengths are reused for high-speed, high-performance transmission;

Furthermore, the technical solutions of the embodiments of the present invention are applicable to radio frequency signals of multiple modulation formats ranging from several GHz to tens of GHz, and can be efficiently transmitted within the distance of the access network at relatively low power.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention.

Claims (18)

1. A multi-wavelength passive optical network system, comprising: an optical line terminal, a wavelength division multiplexing module, and one or more optical network units, characterized in that, The optical line terminal is used to send multi-wavelength downlink signals and receive uplink radio frequency optical signals sent by the optical network unit; The wavelength division multiplexing module is connected to the optical line terminal and the optical network units, and is used to decompose the multi-wavelength downlink signal sent by the optical line terminal into individual signals corresponding to each optical network unit. The single-wavelength downlink signal is sent to the corresponding optical network unit, and the single-wavelength uplink radio frequency optical signal from each optical network unit is combined and sent to the optical line terminal; Each of the optical network units includes: A first optical branching module, configured to divide the downlink signal of a predetermined wavelength among the multi-wavelength downlink signals sent by the optical line terminal into a first path and a second path; a downlink signal receiving module, configured to receive the first downlink signal; An uplink signal modulation module, configured to use the second downlink signal as a modulation light source for the radio frequency uplink service signal of the optical network unit to which the uplink signal modulation module belongs, modulate the radio frequency uplink service signal, and modulate the obtained The uplink radio frequency optical signal is sent to the wavelength division multiplexing module through the first optical branch module, and sent to the optical line terminal by the wavelength division multiplexing module; Each optical network unit also includes: An electrical domain processing module, configured to obtain two same-frequency radio frequency uplink service signals with a predetermined phase difference and carrying uplink service data: a third radio frequency uplink service signal and a fourth radio frequency uplink service signal; The uplink signal modulation module is further configured to divide the downlink signal of the second path into a fifth path and a sixth path, and use the downlink signal of the fifth path and the sixth path as the third path and the sixth path respectively. Modulating light sources for four radio frequency uplink service signals respectively modulate the third and fourth radio frequency uplink service signals, obtain two uplink radio frequency optical signals with a predetermined phase difference after modulation, and modulate the two channels to obtain The uplink radio frequency optical signal is coupled, and the coupled uplink radio frequency optical signal is sent to the optical line terminal. 2. The multi-wavelength passive optical network system according to claim 1, wherein the uplink signal modulation module comprises: The second optical branching module, including a third branch and a fourth branch, is used to divide the second downlink signal into uniform fifth and sixth paths in the downlink direction, and the fifth path signal passes through the third Branch transmission, the sixth signal is transmitted through the fourth branch; The first reflective semiconductor optical amplifier is connected to the third branch of the second optical branching module and the electrical domain processing module, and is used to use the downlink signal of the fifth path as a modulated light source for the third path Modulating the radio frequency uplink service signal, and outputting the modulated first uplink radio frequency optical signal; The second reflective semiconductor optical amplifier is connected to the fourth branch of the second optical branching module and the electrical domain processing module, and is used to use the downlink signal of the sixth path as a modulation light source to the fourth path Modulating the radio frequency uplink service signal, and outputting the modulated second uplink radio frequency optical signal; The second optical branching module is further configured to couple the first uplink radio frequency optical signal and the second uplink radio frequency optical signal, and send the coupled uplink radio frequency optical signal to the Described optical line terminal. 3. The multi-wavelength passive optical network system according to claim 2, wherein the uplink signal modulation module is: a waveguide-type Michelson interferometer supplemented with a reflective semiconductor optical amplifier, and the first and second The two reflective semiconductor optical amplifiers are respectively located at the upper and lower arms of the waveguide Michelson interferometer. 4. The multi-wavelength passive optical network system according to claim 2, wherein when the uplink service signal of the optical network unit is a baseband uplink service signal, the electrical domain processing module includes: The radio frequency signal source is used to generate two radio frequency carrier signals of the same frequency and phase; The first phase shift module is connected to the radio frequency signal source and is used to adjust the phase difference of the two radio frequency carrier signals to obtain a first radio frequency carrier signal and a second radio frequency carrier signal with a predetermined phase difference; a modulation module, configured to divide the baseband uplink service signal into two paths, and modulate the two paths of baseband uplink service signal onto the first radio frequency carrier signal and the second radio frequency carrier signal respectively, so as to obtain the baseband uplink service signal carrying the baseband The third radio frequency uplink service signal and the fourth radio frequency uplink service signal of service signal data. 5. The multi-wavelength passive optical network system according to claim 1, wherein the phase difference between the third radio frequency uplink service signal and the fourth radio frequency uplink service signal is: 0 degrees, 90 degrees or 180 degrees Spend. 6. The multi-wavelength passive optical network system according to claim 4, wherein the uplink signal modulation module further comprises: The second phase shift module is arranged on the third branch or the fourth branch of the second optical branching module, and is used to adjust the phase difference between the first uplink radio frequency optical signal and the second uplink radio frequency optical signal to a predetermined value . 7. The multi-wavelength passive optical network system according to claim 2, wherein when the uplink service signal of the optical network unit is a radio frequency uplink service signal, the electrical domain processing module includes: The third phase shifting module is configured to adjust the phase of the radio frequency uplink service signal divided into two channels to obtain the third radio frequency uplink service signal and the fourth radio frequency uplink service signal with a predetermined phase difference. 8. The multi-wavelength passive optical network system according to claim 1, wherein each of the optical network units further comprises: An optical signal isolator, connected to the first optical branch module and the downlink signal receiving module, is used to directly pass the first downlink signal to the downlink signal receiving module, and prevent the downlink signal receiving module from reflecting back light signal. 9. The multi-wavelength passive optical network system according to claim 1, wherein the multi-wavelength downlink signal sent by the optical line terminal is: a multi-wavelength downlink signal formed after direct intensity modulation of multiple single-wavelength downlink signals downlink signal. 10. A method for realizing wavelength reuse in a multi-wavelength passive optical network system, comprising: Step A, the optical network unit divides the downlink signal of a predetermined wavelength sent by the optical line terminal into a first path and a second path; Step B, the optical network unit receives the first downlink signal, and uses the second downlink signal as a modulation light source for modulating the radio frequency uplink service signal, and obtains the uplink radio frequency after modulating the radio frequency uplink service signal an optical signal, and send the uplink radio frequency optical signal to the optical line terminal; Described step B comprises: Step B1, obtaining two same-frequency radio frequency uplink service signals with a predetermined phase difference and carrying uplink service signal data: a third radio frequency uplink service signal and a fourth radio frequency uplink service signal; Step B2, dividing the second downlink signal into fifth and sixth downlink signals, and using the fifth and sixth downlink signals as the modulation of the third and fourth radio frequency uplink service signals respectively The light source modulates the third and fourth radio frequency uplink service signals respectively, obtains two uplink radio frequency optical signals with a predetermined phase difference after modulation, and converts the two modulated uplink radio signals with a predetermined phase difference The radio frequency optical signal is coupled, and the coupled uplink radio frequency optical signal is sent to the optical line terminal. 11. The method according to claim 10, wherein when the uplink service signal of the optical network unit is a baseband uplink service signal, the step B1 comprises: Use the RF signal source to generate two RF carrier signals with the same frequency and phase; Using the first phase shift module to adjust the phase difference of the two radio frequency carrier signals to obtain a first radio frequency carrier signal and a second radio frequency carrier signal with a predetermined phase difference; Divide the baseband uplink service signal sent by the optical network unit into two paths, modulate the two paths of baseband uplink service signal onto the first radio frequency carrier signal and the second radio frequency carrier signal respectively, and obtain the baseband uplink service carrying the The third radio frequency uplink service signal and the fourth radio frequency uplink service signal of the signal data. 12. The method according to claim 10, wherein when the uplink service signal of the optical network unit is a radio frequency uplink service signal, the step B1 comprises: dividing the radio frequency uplink service signal into two paths; Using the third phase shift module to adjust the phase difference of the two radio frequency uplink service signals to obtain the third radio frequency uplink service signal and the fourth radio frequency uplink service signal with a predetermined phase difference. 13. The method according to any one of claims 10-12, wherein the optical network unit implements the above step B through an uplink signal modulation module, and the uplink signal modulation module includes: The second optical branching module includes a third branch and a fourth branch, configured to divide the second downlink signal into a fifth path and a sixth path, the fifth path signal is transmitted through the third branch, and the The sixth signal is transmitted through the fourth branch; The first reflective semiconductor optical amplifier is connected to the third branch of the second optical branch module, and is used to modulate the third radio frequency uplink service signal by using the fifth downlink signal as a modulation light source, and output the modulated first uplink radio frequency optical signal; The second reflective semiconductor optical amplifier is connected to the fourth branch of the second optical branch module, and is used to modulate the fourth radio frequency uplink service signal by using the sixth downlink signal as a modulation light source, and output the modulated second uplink radio frequency optical signal; The second optical branching module is further configured to couple the first uplink radio frequency optical signal and the second uplink radio frequency optical signal, and send the coupled uplink radio frequency optical signal to the optical line terminal. 14. An optical network unit, comprising: The first optical branching module is configured to divide the downlink signal of a predetermined wavelength among the multi-wavelength downlink signals sent by the optical line terminal into a first path and a second path; a downlink signal receiving module, configured to receive the first downlink signal; An uplink signal modulation module, configured to use the second downlink signal as a modulation light source for the radio frequency uplink service signal of the optical network unit to which the uplink signal modulation module belongs, modulate the radio frequency uplink service signal, and modulate the obtained sending an uplink radio frequency optical signal to the optical line terminal; An electrical domain processing module, configured to obtain two same-frequency radio frequency uplink service signals with a predetermined phase difference and carrying uplink service data: a third radio frequency uplink service signal and a fourth radio frequency uplink service signal; The uplink signal modulation module is further configured to divide the downlink signal of the second path into a fifth path and a sixth path, and use the downlink signal of the fifth path and the sixth path as the third path and the sixth path respectively. Modulating light sources for four radio frequency uplink service signals respectively modulate the third and fourth radio frequency uplink service signals to obtain two modulated uplink radio frequency optical signals with a predetermined phase difference, and convert the modulated uplink radio frequency optical signals with a predetermined phase difference Coupling the modulated uplink radio frequency optical signals of the two channels, and sending the coupled uplink radio frequency optical signals to the optical line terminal. 15. The optical network unit according to claim 14, wherein the uplink signal modulation module comprises: The second optical branching module, including a third branch and a fourth branch, is used to divide the second downlink signal into uniform fifth and sixth paths in the downlink direction, and the fifth path signal passes through the third Branch transmission, the sixth signal is transmitted through the fourth branch; The first reflective semiconductor optical amplifier is connected to the third branch of the second optical branching module and the electrical domain processing module, and is used to use the downlink signal of the fifth path as a modulated light source for the third path Modulating the radio frequency uplink service signal, and outputting the modulated first uplink radio frequency optical signal; The second reflective semiconductor optical amplifier is connected to the fourth branch of the second optical branching module and the electrical domain processing module, and is used to use the downlink signal of the sixth path as a modulation light source to the fourth path Modulating the radio frequency uplink service signal, and outputting the modulated second uplink radio frequency optical signal; The second optical branching module is further configured to couple the first uplink radio frequency optical signal and the second uplink radio frequency optical signal, and send the coupled uplink radio frequency optical signal to the Described optical line terminal. 16. The optical network unit according to claim 15, wherein the uplink signal modulation module is: a waveguide Michelson interferometer supplemented with a reflective semiconductor optical amplifier, and the first and second reflective semiconductor The optical amplifiers are respectively located at the upper and lower arms of the waveguide Michelson interferometer. 17. The optical network unit according to claim 15, wherein when the uplink service signal of the optical network unit is a baseband uplink service signal, the electrical domain processing module includes: The radio frequency signal source is used to generate two radio frequency carrier signals of the same frequency and phase; The first phase shift module is connected to the radio frequency signal source and is used to adjust the phase difference of the two radio frequency carrier signals to obtain a first radio frequency carrier signal and a second radio frequency carrier signal with a predetermined phase difference; A modulating module, configured to divide the baseband uplink service signal into two paths, and modulate the two paths of baseband uplink signal to the first radio frequency carrier signal and the second radio frequency carrier signal respectively, so as to obtain the baseband uplink service carrying The third radio frequency uplink service signal and the fourth radio frequency uplink service signal of the signal data. 18. The optical network unit according to claim 14, wherein the phase difference between the third radio frequency uplink service signal and the fourth radio frequency uplink service signal is: 0 degrees, 90 degrees or 180 degrees.

Images