CN103733547B - Optical line terminal, optical network system and signal processing method - Google Patents

Abstract

The present invention relates to an optical line terminal, an optical network unit, an optical network system, and a signal processing method. The optical line terminal includes: a laser, a multiplexer, an optical amplifier, an optical modulator, a first optical fiber, and a second optical fiber; The first optical fiber is used to excite the direct current light generated by the laser through stimulated Brillouin scattering SBS to form local oscillator light and the first sub-light wave of reverse transmission, and transmit the local oscillator light to The multiplexer; the second optical fiber, used to excite the optical signal amplified and processed by the optical amplifier through the SBS to form an optical carrier and a second sub-light wave for reverse transmission, and transmit the optical carrier to The optical modulator; the multiplexer is used to combine the local oscillator light formed by the first optical fiber and the signal light formed by the optical modulator to form an optical multi-band multiplexing signal and output it. The invention can overcome the high-frequency attenuation caused by optical fiber dispersion, and overcome the insufficient frequency response and roll-off of various photoelectric devices at high frequencies.

Description

Optical line terminal, optical network system and signal processing method

technical field

The invention relates to the technical field of network communication, in particular to an optical line terminal, an optical network unit, an optical network system and a signal processing method.

Background technique

Passive Optical Network (PON) is a point-to-multipoint optical access technology, which has gradually become the mainstream technology in the field of broadband access. With the rapid development of communication, interactive games, etc., the demand for access bandwidth is getting higher and higher. In the face of future broadband evolution, larger bandwidth, long distance, and large branches are required.

At present, most PONs are based on Time Division Multiple Address (TDMA). A typical PON system includes an Optical Line Terminal (OLT), an Optical Splitter, and an Optical Network Unit (ONU). Network Unit, ONU), in which the optical splitter and the backbone optical fiber constitute an optical distribution network (Optical Distribution Network, ODN), and multiple optical network units are connected to the optical splitter through optical fibers, and then connected to the optical line through the backbone optical fiber after aggregation terminal (local end). The optical network unit shares the backbone fiber through TDMA.

Most of the existing optical network systems adopt Multi Band Frequency Division Multiplexing (Multi Band Frequency Division Multiplexing, multi-band FDM) technology. The transmitting end (that is, the optical line terminal) generates multi-band FDM signals in the electrical domain, and uses the bit loading algorithm, namely Transmit fewer bits on poor-quality channels and turn off poor-quality channels to perform multi-band transmission (Multi Band Transmission), which can make full use of the bandwidth.

However, this type of electrical multi-band FDM requires a high bandwidth of radio frequency devices. Such radio frequency devices have frequency roll-off, which leads to serious degradation of the performance of radio frequency devices at high frequencies. Even though electrical multi-band FDM requires complex channel estimation and In the bit-loading algorithm, there are still many high-frequency parts that cannot be utilized due to severe frequency attenuation, and the requirements for optical filters are also high.

Contents of the invention

The object of the present invention is to provide an optical line terminal, an optical network unit, an optical network system and a signal processing method, which can transmit at the baseband with the best transmission performance of optical fibers and radio frequency devices, can overcome the high frequency attenuation caused by optical fiber dispersion, and overcome various This optoelectronic device has insufficient frequency response and roll-off at high frequencies.

To achieve the above object, the first aspect of the present invention provides an optical line terminal, which includes: a laser, a multiplexer, an optical amplifier, an optical modulator, a first optical fiber, and a second optical fiber;

The laser is used to generate direct current light;

The first optical fiber is connected with the laser and the multiplexer, and is used to excite the DC light generated by the laser through stimulated Brillouin scattering (SBS) to form local oscillator light and reverse transmission the first sub-light wave, and transmit the local oscillator light to the multiplexer; wherein the local oscillator light is an optical signal with an optical power in the direct current light that is less than the SBS threshold, and the first sub-light wave is the An optical signal whose optical power is greater than the SBS threshold in the direct current light;

The optical amplifier is connected to the first optical fiber and the second optical fiber, and is used to perform optical signal amplification processing on the first sub-light wave, and transmit the amplified optical signal to the first sub-wave Two optical fibers;

The second optical fiber is connected with the optical amplifier and the optical modulator, and is used to excite the optical signal amplified and processed by the optical amplifier through the SBS to form an optical carrier and a second sub-light wave for reverse transmission, and transmitting the optical carrier to the optical modulator; wherein, the second sub-optical wave is an optical signal whose optical power is greater than the SBS threshold in the amplified optical signal, and the optical carrier is the amplified optical signal Among the following optical signals, the optical signals whose optical power is less than the SBS threshold;

The optical modulator is connected to the second optical fiber and the multiplexer, and is used to modulate the optical carrier and the input downlink electrical signal to form signal light, and transmit it to the multiplexer;

The multiplexer is connected to the first optical fiber and the optical modulator, and is used to combine the local oscillator light formed by the first optical fiber and the signal light formed by the optical modulator to form an optical multi-band complex Use the signal and output.

With reference to the first aspect, in a first possible implementation manner of the first aspect, the first optical fiber is connected to the laser through a first optical circulator, and the first end of the first optical circulator is connected to the The output end of the laser is connected, the second end of the first optical circulator is connected to the first optical fiber, and the DC light generated by the laser is transmitted to the first optical fiber, and the first optical circulator The third end of the optical circulator is connected to the input end of the optical amplifier, and transmits the first sub-light wave formed by the first optical fiber to the optical amplifier.

With reference to the first aspect, in a second possible implementation manner of the first aspect, the optical amplifier is connected to the second optical fiber through a second optical circulator, and the first end of the second optical circulator is connected to the The output end of the optical amplifier is connected, the second end of the second optical circulator is connected to the second optical fiber, and the optical signal amplified by the optical amplifier is transmitted to the second optical fiber, so The third end of the second optical circulator is connected to the next optical amplifier, and transmits the second sub-light wave formed in the second optical fiber to the next optical amplifier.

With reference to the first aspect, in a third possible implementation manner of the first aspect, the frequency difference between the first sub-light wave formed in the first optical fiber and the DC light generated by the laser is Δf, and the The frequency difference between the second sub-light wave formed in the second optical fiber and the first sub-light wave is Δf.

In a second aspect, the present invention also provides an optical network unit, which includes: a photoelectric receiver, a bandpass filter, and a demodulator;

The photoelectric receiver is used to receive the optical multi-band multiplexing signal sent by the optical line terminal, the optical multi-band multiplexing signal includes a local oscillator light and a plurality of signal lights, and the signal light is respectively connected to the local oscillator light Perform coherent frequency mixing to obtain electrical multi-band multiplexing signals;

The band-pass filter is used to perform band-pass filtering on the electrical multi-band multiplexing signal obtained by the photoelectric receiver, obtain an electrical signal in a required frequency band, and transmit it to the demodulator for demodulation.

In a third aspect, the present invention also provides an optical network system, the optical network system comprising: the optical line terminal described in the embodiment of the present invention, the optical network unit described in the embodiment of the present invention, and an optical distribution network ODN;

The optical line terminal is connected to the optical network unit through the optical distribution network.

In a fourth aspect, the present invention also provides a method for processing an optical network signal, the method comprising:

The DC light generated by the laser is transmitted in the first optical fiber, excited by stimulated Brillouin scattering SBS to form local oscillator light and the first sub-light wave of reverse transmission; wherein, the local oscillator light is the light in the DC light An optical signal with power less than the SBS threshold, the first sub-wave is an optical signal with optical power greater than the SBS threshold;

Perform optical signal amplification processing on the first sub-light wave, transmit the amplified optical signal in the second optical fiber, and excite it through the SBS to form an optical carrier and a second sub-light wave for reverse transmission; wherein, the The second sub-light wave is an optical signal with an optical power greater than the SBS threshold in the amplified optical signal, the optical carrier is an optical signal with an optical power less than the SBS threshold in the amplified optical signal, and the optical The carrier is used to modulate with the input downlink electrical signal to form signal light;

The local oscillator light is combined with the signal light to form an optical multi-band multiplexing signal, and the optical multi-band multiplexing signal is output to an optical network unit.

With reference to the fourth aspect, in a first possible implementation manner of the fourth aspect, the frequency difference between the first sub-light wave and the DC light generated by the laser is Δf, and the second sub-light wave and the first sub-light wave are The frequency difference of a sub-wave is △f.

With reference to the fourth aspect, in a second possible implementation manner of the fourth aspect, before outputting the optical multi-band multiplexing signal to the optical network unit, it further includes: combining multiple channels of the optical multi-band multiplexing signal form one path, and transmit the composite optical multi-band multiplexing signal to the optical network unit through the optical fiber.

In the fifth aspect, the present invention also provides an optical network signal processing method, the method comprising:

receiving the optical multi-band multiplexing signal sent by the optical line terminal, the optical multi-band multiplexing signal includes local oscillator light and multiple signal lights, and the signal light is coherently mixed with the local oscillator light respectively to obtain electrical multiplex With multiplexing signal;

performing band-pass filtering on the electrical multi-band multiplexed signal to obtain an electrical signal in a required frequency band, and performing demodulation processing to obtain a downlink signal received by the optical line terminal.

The optical line terminal, optical network unit, optical network system and signal processing method provided by the present invention generate optical carriers with stable frequency intervals between wavelengths through SBS excitation, so that all sub-band signals can have the best transmission performance in optical fibers and radio frequency devices The baseband for transmission can overcome the high-frequency attenuation caused by fiber dispersion, and overcome the insufficient frequency response and roll-off of various optoelectronic devices at high frequencies.

Description of drawings

FIG. 1 is a schematic structural diagram of an optical network system provided by Embodiment 1 of the present invention;

FIG. 2a is a schematic diagram of an optical multi-band multiplexing signal output by an optical line terminal provided in Embodiment 1 of the present invention;

Fig. 2b is a schematic diagram of the electrical multi-band multiplexing signal output by the photoelectric receiver provided in Embodiment 1 of the present invention;

FIG. 2c is a schematic diagram of a signal output by a bandpass filter provided by Embodiment 1 of the present invention;

FIG. 3 is a schematic structural diagram of an optical network system provided in Embodiment 2 of the present invention;

FIG. 4 is a schematic structural diagram of an optical network system provided by Embodiment 3 of the present invention;

FIG. 5 is a flow chart of an optical network signal processing method provided in Embodiment 4 of the present invention;

FIG. 6 is a flowchart of another optical network signal processing method provided by Embodiment 4 of the present invention.

detailed description

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

The downlink mode of the passive optical network PON adopts the broadcast mode, and the broadcast information is distributed to several user terminals through an optical beam splitter. The optical line terminal, optical network unit, optical network system, and signal processing method provided by the embodiments of the present invention are compatible with existing deployed PON networks (PON based on optical beam splitters), and are also applicable to other PON structures, as follows First-generation access network structure: wavelength division multiplexing passive optical network WDM PON, time division wavelength division multiplexing passive optical network TWDM PON, etc.

Embodiment one

Fig. 1 is a schematic structural diagram of the optical network system provided by this embodiment. As shown in Fig. 1, the optical network system of the present invention includes: an optical line terminal 1, an optical beam splitter 2 and an optical network unit 3, a plurality of optical network units 3 The optical beam splitter 2 is connected to the optical beam splitter 2 through the optical fiber 4 , and the optical beam splitter 2 is connected to the optical line terminal 1 through the main optical fiber 5 .

The optical line terminal 1 includes: a laser 11 , a first optical circulator 12 , a first optical fiber 13 , an optical amplifier 14 , a second optical circulator 15 , a second optical fiber 16 , an optical modulator 17 and a multiplexer 18 .

A laser 11 is used to generate direct current light. The laser 11 is connected to the first optical fiber 13 through the first optical circulator 12, and the first optical fiber 13 is used to excite the DC light λ ₀ generated by the laser 11 through stimulated Brillouin scattering SBS to form local oscillator light and reverse transmission The first sub-light wave λ ₁ , the first optical fiber 13 is also connected to the multiplexer 18 , and transmits the local oscillator light to the multiplexer 18 . Wherein, the local oscillator light is an optical signal whose optical power is less than the SBS threshold in the direct current light _λ0 , and the _first sub-light wave λ1 is an optical signal whose optical power is greater than the SBS threshold in the direct current light _λ0 . There is no frequency difference between the local oscillator light formed in the first optical fiber 13 and the direct-current light λ ₀ that laser 11 produces, the frequency difference between the first sub-light wave λ ₁ formed in the first optical fiber 13 and the direct-current light λ ₀ that laser 11 produces is △f, and the size of this frequency difference △f can be controlled.

The optical amplifier 14 is connected to the first optical fiber 13 through the first optical circulator 12, and is connected to the second optical fiber 16 through the second optical circulator 15, and is used for the described first sub-light wave formed in the first optical fiber 13 λ1 performs optical signal amplification processing, and transmits the amplified optical signal to the second optical fiber ₁₆ through the second optical circulator 15 .

Wherein, the first end of the first optical circulator 12 is connected with the output end of the laser 11, and the second end of the first optical circulator 12 is connected with the first optical fiber 13, and the direct current light λ ₀ that the laser 11 produces transmitted to the first optical fiber 13. The third end of the first optical circulator 12 is connected to the input end of the optical amplifier 14, and transmits the first sub-wave λ1 formed by the _first optical fiber 13 to the optical amplifier 14.

The first end of the second optical circulator 15 is connected with the output end of the optical amplifier 14, and the second end of the second optical circulator 15 is connected with the second optical fiber 16, and the optical signal after the optical amplifier 14 amplifies and processes is transmitted to The second optical fiber 16, the third end of the second optical circulator 15 is connected to the next optical amplifier, and transmits the second sub-light wave formed in the second optical fiber 16 to the next optical amplifier.

The second optical fiber 16 is connected with the optical modulator 17, and is used to excite the optical signal amplified and processed by the optical amplifier 14 through the SBS to form an optical carrier and the second sub-light wave λ ₂ for reverse transmission, and transmit the optical carrier to the light modulator 17. Wherein, the _second sub-light wave λ2 is an optical signal whose optical power is greater than the SBS threshold in the amplified optical signal, and the optical carrier is an optical signal whose optical power is less than the SBS threshold in the amplified optical signal Signal. There is no frequency difference between the optical carrier formed in the second optical fiber 16 and the first sub-light wave λ1, and the frequency difference between the _second sub-light wave _λ2 and the _first sub-light wave λ1 formed in the second optical fiber 16 is Δf.

The optical modulator 17 is connected to the second optical fiber 16 and the multiplexer 18, and is used to modulate the optical carrier formed in the second optical fiber 16 and the input downlink electrical signal to form signal light, and transmit it to the multiplexer 18.

The multiplexer 18 is connected to the first optical fiber 13 and the optical modulator 17, and is used to combine the local oscillator light formed by the first optical fiber 13 and the signal light formed by the optical modulator 17 to form an optical multi-band multiplexing signal and output it, through The trunk optical fiber 5 is transmitted to the optical beam splitter 2 . The optical beam splitter 2 splits the optical multi-band multiplexing signal to each optical network unit 3 . That is to say, the signal light formed by each second sub-light wave enters the optical fiber and the optical beam splitter 2 through the multiplexer 18 , and finally reaches each optical network unit 3 .

It should be noted that, in the embodiment of the present invention, the sub-light wave formed in the reverse direction in each optical fiber can be optically amplified and then excited by the SBS to form the next sub-light wave with a frequency difference of Δf. As shown in the figure, the second sub-light wave of reverse transmission formed by the second optical fiber 16 can be connected with the next optical amplifier through the second optical circulator 15, and the next optical amplifier can be connected with the next optical amplifier through the next optical circulator. The second optical fiber is connected, and the next second optical fiber is connected to the next optical modulator. By analogy, the sub-light waves λ ₄ , λ ₅ , and λ _n can be sequentially generated by SBS excitation. The frequency difference between all two adjacent sub-waves is △f. In this way, a plurality of optical carriers can be generated, which can be modulated with a plurality of different input downlink electrical signals to form a plurality of signal lights, which are combined by the multiplexer 18 to form an optical multi-band multiplexing signal.

In this way, all delivered electrical signals are transmitted at the baseband with the best performance of the optical channel, and are respectively modulated onto the sub-light waves λ ₁ , λ ₂ , ..λ _n by the optical modulator. Data is not modulated on the direct current light λ ₀ , and is sent down to each optical network unit 3 as local oscillator light, so as to perform self-coherent reception and generate electrical multi-band signals. In this way, an optical domain multi-band frequency division multiplexing signal is formed on the optical line terminal, that is, all electrical signals are in the baseband, and different baseband electrical signals are carried by multiple sub-light waves with fixed intervals.

The optical network unit 3 includes: a photoelectric receiver 31 , a bandpass filter 32 and a demodulator 33 .

The photoelectric receiver 31 is used for receiving the optical multi-band multiplexing signal sent by the optical line terminal 1 . Wherein, the optical multi-band multiplexing signal includes a local oscillator light and multiple signal lights, and each signal light is coherently mixed with the local oscillator light to obtain an electrical multi-band multiplexing signal.

The band-pass filter 32 is used to perform band-pass filtering on the electrical multi-band multiplexing signal obtained by the photoelectric receiver 31, obtain the electrical signal in the required frequency band, and transmit it to the demodulator 33 for demodulation to obtain an optical line terminal 1 Downlink signal received.

The direct current light λ ₀ is used as local oscillator light coherently received in the downlink, and generates coherent frequency mixing in the photoelectric receiver 31 . Since the local oscillator light is sent together with the downlink signal and has the same polarization state as the signal, it is also called the self-coherent receiving method. After passing through the photoelectric receiver 31, each signal light is coherently mixed with the local oscillator light to obtain an electrical multi-band multiplexing signal. The optical multi-band multiplexing signal shown in Figure 2a includes multiple signal lights with a wavelength frequency difference of Δf in the spectrum. Each signal light Δf is usually small, generally not exceeding 10 GHz. After coherent mixing , to obtain multiple electrical signals with a frequency interval of △f on the electrical spectrum, as shown in Figure 2b. After being filtered by the band-pass filter 32, an electrical signal of a certain frequency band is obtained. As shown in FIG. The downlink signal received by line terminal 1. This avoids various degradations of the electrical signal when it is transmitted in the optical fiber. The optical network unit 3 only needs to use an electrical band-pass filter (BPF) to filter out the required electric band for demodulation, which greatly reduces the complexity, power consumption and cost of the optical network unit.

The embodiment of the present invention proposes a passive optical network system with multi-band multiplexing in the optical domain, which utilizes optical fiber stimulated Brillouin scattering (SBS) to generate multiple sub-waves, and each sub-band is on each optical carrier in the form of baseband Transmission, that is, transmission in the baseband with the best transmission performance of optical fiber and RF devices, can overcome the high-frequency attenuation caused by fiber dispersion, and overcome the insufficient frequency response and roll-off of various optoelectronic devices at high frequencies. Moreover, since the frequency interval between the wavelengths of the light waves generated is stable, it is not affected by the wavelength jitter of the laser, and can generate sub-light waves with a narrow frequency interval, with high precision, and the polarization states of each light wavelength are consistent, ensuring complete coherent mixing in the receiver. Electrical multiplex signal. At the same time, when the PD is receiving, the nonlinear mixing noise between sub-bands is reduced. Due to the high power of the local oscillator light, the receiving sensitivity is also improved.

In addition, a large number of optical network units 3 and optical distribution networks have been deployed at present. During the network upgrade process, the optical distribution network ODN can remain unchanged. The optical network unit 2 is directly oriented to end users. During the upgrade process, it is necessary to maintain sufficient advantages in cost, so that the existing optical network system based on the optical splitter can be smoothly upgraded while keeping the ODN unchanged.

Embodiment two

The invention can also be applied in wavelength division multiplexing self-coherent passive optical network system.

FIG. 3 is a schematic structural diagram of the optical network system provided by this embodiment. As shown in FIG. 3 , the optical network system of the present invention includes: multiple optical line terminals 1, multiple optical network units 3, and an arrayed waveguide grating (AWG) 61 , arrayed waveguide grating 62 and optical fiber 4 for connection. Arrayed waveguide gratings 61 connected to multiple optical line terminals 1 are connected to arrayed waveguide gratings 62 through trunk optical fibers 5 , and arrayed waveguide gratings 62 are connected to multiple optical network units 3 .

The internal structure of each optical line terminal 1 is the same as that of the optical line terminal 1 in the first embodiment, and each optical network unit 3 is the same as the optical network unit 3 in the first embodiment, and the specific processing process is also the same, and will not be repeated here. repeat.

Multiple optical line terminals 1 are connected to the arrayed waveguide grating 61 through the optical fiber 4, and the input end of the arrayed waveguide grating 61 is connected to the multiplexer 13 of the multiple optical line terminals 1, which is used to transmit the multiple optical line terminals 1 Optical multiplexed signals are multiplexed into a single optical fiber. Multiple optical network units 3 are connected to arrayed waveguide gratings 62 through optical fibers 4, and multiple output ends of arrayed waveguide gratings 62 are respectively connected to photoelectric receivers 31 of optical network units 3, so that optical network units 3 pass through arrayed waveguide gratings 62 Receive the optical multi-band multiplexing signal sent by the optical line terminal.

The optical wavelength of the DC light emitted by each optical line terminal 1 is different, and the frequency difference between the optical wavelengths generated by two optical line terminals 1 is usually much larger than the frequency difference between the sub-waves generated by the same laser through the SBS principle△ f, generally speaking, Δf does not exceed 10 GHz, and the frequency difference of the optical wavelengths generated by the lasers of the two optical line terminals 1 can reach 100 GHz. In this way, the arrayed waveguide grating 61 can be used to synthesize optical signals of different wavelengths for transmission, and then the arrayed waveguide grating 62 can be used to separate the optical signals of different wavelengths.

Embodiment three

The invention can also be applied to the time division wavelength division passive optical network system where the optical beam splitter and the arrayed waveguide grating coexist.

Fig. 4 is a schematic structural diagram of the optical network system provided by this embodiment. As shown in Fig. 4, the optical network system of the present invention includes: a plurality of optical line terminals 1, an optical beam splitter 2, a plurality of optical network units 3, an array A waveguide grating 61, an arrayed waveguide grating 62, and an optical fiber 4 for connection.

The structure in this embodiment is similar to that of Embodiment 2, the difference is that in the ONU side, after the arrayed waveguide grating 62, it can also be connected to each ONU 3 through an optical beam splitter 2, which can improve Access user density, extended access distance, suitable for multi-site integration, to adapt to the passive optical network system where time division and wavelength division multiplexing coexist.

The above is a detailed description of the optical network system provided by the present invention, and the optical network communication method provided by the present invention will be described in detail below.

Embodiment Four

Fig. 5 is a flow chart of an optical network signal processing method provided in this embodiment. As shown in Fig. 5, on the optical line terminal side, the optical network signal processing method of the present invention includes:

S101. The DC light generated by the laser is transmitted in the first optical fiber and excited by the SBS to form the local oscillator light and the first sub-light wave transmitted in reverse.

Wherein, the local oscillator light is an optical signal whose optical power is less than the SBS threshold in the direct current light, and the first sub-wave is an optical signal whose optical power is greater than the SBS threshold. The frequency difference between the first sub-light wave and the DC light generated by the laser is Δf.

Specifically, the principle of SBS: When the optical power of the laser λ ₀ entering the fiber reaches a certain value, due to SBS, a sub-light wave (Stokes Stockes light wave) λ ₁ will be excited, and λ ₁ has the following characteristics: 1) λ ₀ is opposite to λ ₁ ; 2) There is a certain frequency difference △f between λ ₁ and λ ₀ , which can be controlled; 3) λ ₁ and λ ₀ have the same polarization state; 4) If λ ₁ enters the fiber again , when the power reaches the threshold value of SBS, the Stokes light λ ₂ of the next order will be excited again, and the frequency difference between λ ₂ and λ ₁ is still △f; 5) SBS can be excited in any fiber, and in nonlinear Highly nonlinear fibers (HNF) with very high coefficients have lower excitation thresholds and require very short fiber lengths.

S102. Perform optical signal amplification processing on the first sub-light wave, transmit the amplified optical signal in the second optical fiber, and excite it through the SBS to form an optical carrier and a second sub-light wave for reverse transmission, so The above-mentioned optical carrier is used to form signal light after being modulated with the input downlink electrical signal.

Wherein, the second sub-light wave is an optical signal with an optical power greater than the SBS threshold in the amplified optical signal, and the optical carrier is an optical signal with an optical power less than the SBS threshold in the amplified optical signal. The frequency difference between the second sub-light wave and the first sub-light wave is Δf.

S103. The local oscillator light is combined with the signal light to form an optical multi-band multiplexed signal, and the optical multi-band multiplexed signal is output to an optical network unit.

Optionally, before outputting the optical multi-band multiplexing signal to the optical network unit, it also includes: combining multiple channels of the optical multi-band multiplexing signal into one, and transmitting the composite optical multi-band multiplexing signal through an optical fiber to the optical network unit. Specifically, multiple channels of the optical multi-band multiplexing signal can be combined into one channel through an arrayed waveguide grating, and then transmitted to the optical network unit side through a backbone optical fiber to reach each optical network unit.

FIG. 6 is a flow chart of another optical network signal processing method provided in this embodiment. As shown in FIG. 6, on the optical network unit side, the optical network signal processing method of the present invention includes:

S201. Receive the optical multi-band multiplexing signal sent by the optical line terminal, the optical multi-band multiplexing signal includes local oscillator light and multiple signal lights, and the signal light is coherently mixed with the local oscillator light respectively to obtain Electrical multiplex signal.

The optical network unit can receive the optical multi-band multiplexing signal sent by the optical line terminal through the optical beam splitter, and can also receive the optical multi-band multiplexing signal sent by the optical line terminal through the arrayed waveguide grating.

Optionally, receiving the optical multi-band multiplexing signal sent by the optical line terminal includes:

Receiving composite optical multi-band multiplexed signals sent by multiple optical line terminals, separating the composite optical multi-band multiplexed signals to obtain single optical multi-band multiplexed signals respectively.

S202. Perform band-pass filtering on the electrical multi-band multiplexed signal, acquire an electrical signal in a required frequency band, and perform demodulation processing to obtain a downlink signal received by the optical line terminal.

The optical line terminal, optical network unit, optical network system and signal processing method provided by the present invention utilize stimulated Brillouin scattering (SBS) excitation of an optical fiber, obtain an optical carrier with a stable frequency interval between wavelengths through a step-by-step structure, and utilize optical modulation Modulate and load the downlink electrical signal, so that all sub-band signals can be transmitted in the baseband with the best transmission performance of optical fiber and radio frequency devices, so as to overcome the high-frequency attenuation caused by optical fiber dispersion and the high-frequency interference of various optoelectronic devices Insufficient frequency response, roll-off. Moreover, since the frequency interval between the wavelengths of the light waves generated is stable, it is not affected by the wavelength jitter of the laser, and can generate sub-light waves with a narrow frequency interval, with high precision, and the polarization states of each light wavelength are consistent, ensuring complete coherent mixing in the receiver. Electrical multiplex signal. At the same time, when the PD is receiving, the non-linear mixing noise between sub-bands is reduced.

Professionals should further realize that the units and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the relationship between hardware and software Interchangeability. In the above description, the composition and steps of each example have been generally described according to their functions. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

The steps of the methods or algorithms described in connection with the embodiments disclosed herein may be implemented by hardware, software modules executed by a processor, or a combination of both. Software modules can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other Any other known storage medium.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (8)

1. an optical line terminal, it is characterised in that described optical line terminal includes: laser instrument, conjunction ripple Device, image intensifer, photomodulator, the first optical fiber and the second optical fiber；

Described laser instrument, is used for producing direct current light；

Described first optical fiber, is connected with described laser instrument and described wave multiplexer, for by described laser instrument The described direct current light produced excites by stimulated Brillouin scattering SBS, formation local oscillator light and reverse transfer First sub-light wave, and give described wave multiplexer by described local oscillator optical transport；Wherein, described local oscillator light is described In direct current light, luminous power is less than the optical signal of SBS threshold, and described first sub-light wave is light in described direct current light Power is more than the optical signal of SBS threshold；

Described image intensifer, is connected with described first optical fiber and described second optical fiber, for described the One sub-light wave carries out optical signal amplification process, and the optical signal transmission after described processing and amplifying is given described the Two optical fiber；

Described second optical fiber, is connected with described image intensifer and described photomodulator, for by described light Optical signal after amplifier processing and amplifying is excited by SBS, forms the second son of light carrier and reverse transfer Light wave, and described light carrier is transferred to described photomodulator；Wherein, described second sub-light wave is described In optical signal after processing and amplifying, luminous power is more than the optical signal of SBS threshold, described light carrier be described in put In optical signal after big process, luminous power is less than the optical signal of SBS threshold；

Described photomodulator, is connected with described second optical fiber and described wave multiplexer, for being carried by described light The downstream electrical signals of ripple and input forms flashlight after being modulated, and is transferred to described wave multiplexer；

Described wave multiplexer, is connected with described first optical fiber and described photomodulator, for by described first The photosynthetic wave signal that the local oscillator light that optical fiber is formed is formed with described photomodulator forms light many bands multiplexed signals also Output.

Optical line terminal the most according to claim 1, it is characterised in that described first optical fiber passes through First optical circulator is connected with described laser instrument, the first end of described first optical circulator and described laser The outfan of device is connected, and the second end of described first optical circulator is connected with described first optical fiber, will The described direct current light that described laser instrument produces is transferred to described first optical fiber, the of described first optical circulator Three ends are connected with the input of described image intensifer, the described first sub-light formed by described first optical fiber Ripple is transferred to described image intensifer.

Optical line terminal the most according to claim 1, it is characterised in that described image intensifer passes through Second optical circulator is connected with described second optical fiber, the first end of described second optical circulator and described light The outfan of amplifier is connected, and the second end of described second optical circulator is connected with described second optical fiber, Optical signal transmission after described image intensifer processing and amplifying is given described second optical fiber, described second light annular 3rd end image intensifer described with the next one of device is connected, described the will formed in described second optical fiber Two sub-light wave transmissions give next described image intensifer.

Optical line terminal the most according to claim 1, it is characterised in that shape in described first optical fiber The described first sub-light wave become is △ f with the frequency difference of the direct current light that described laser instrument produces, described second optical fiber The described second sub-light wave of middle formation and the frequency difference of described first sub-light wave are △ f.

5. an optical network system, it is characterised in that described optical network system includes: such as claim 1～ Optical line terminal, optical network unit and Optical Distribution Network described in 4 arbitrary claims；

Described optical network unit includes: photelectric receiver, band filter and demodulator；

Described photelectric receiver, for receiving light many bands multiplexed signals that described optical line terminal sends, institute State light many bands multiplexed signals and include local oscillator light and multiple flashlight, described flashlight respectively with described local oscillator light Carry out relevant mixing, obtain electric many bands multiplexed signals；

Described band filter, enters for the described electricity many bands multiplexed signals obtaining described photelectric receiver Row bandpass filtering, obtains the signal of telecommunication of required frequency range, and transmission to described demodulator is demodulated；

Described optical line terminal is connected with described optical network unit by described Optical Distribution Network.

6. an optical network signal processing method, it is characterised in that described method includes:

The direct current light that laser instrument produces is transmitted in the first optical fiber, is excited by stimulated Brillouin scattering SBS, Form local oscillator light and the first sub-light wave of reverse transfer；Wherein, described local oscillator light is light in described direct current light Power is less than the optical signal of SBS threshold, and described first sub-light wave is the light letter that luminous power is more than SBS threshold Number；

Described first sub-light wave is carried out optical signal amplification process, and by the optical signal after described processing and amplifying Second optical fiber transmits, is excited by SBS, form light carrier and the second sub-light wave of reverse transfer； Wherein, in the optical signal after described second sub-light wave is described processing and amplifying, luminous power is more than SBS threshold Optical signal, described light carrier is the light that in the optical signal after described processing and amplifying, luminous power is less than SBS threshold Signal, described light carrier forms flashlight with the downstream electrical signals of input after being modulated；

Described local oscillator light and described photosynthetic wave signal form light many bands multiplexed signals, and light many bands multiplexing are believed Number output to optical network unit.

Method the most according to claim 6, it is characterised in that described first sub-light wave swashs with described The frequency difference of the direct current light that light device produces is △ f, and described second sub-light wave with the frequency difference of described first sub-light wave is △f。

Method the most according to claim 6, it is characterised in that described by defeated for light many bands multiplexed signals Before going out to optical network unit, also include: light many bands multiplexed signals described in multichannel is combined into a road, will Light many bands multiplexed signals after Fu He sends optical network unit to by optical fiber.