CN114301528A - Method and system for suppressing balanced enhanced phase noise in optical fiber communication - Google Patents
Method and system for suppressing balanced enhanced phase noise in optical fiber communication Download PDFInfo
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Abstract
The invention provides a method and a system for suppressing balanced enhanced phase noise in optical fiber communication, which relate to coherent optical communication and signal processing, wherein a conjugate dual carrier generated in an optical transmitter is used as a carrier, signal data information of the optical transmitter is transmitted to an optical receiver by means of external modulation, the optical receiver performs digital signal processing through a DSP, the obtained laser phase noise can be converted into extra noise, namely balanced enhanced noise, in the dispersion compensation process, the problem that the balanced enhanced noise and the laser phase noise in the optical transmitter are not easy to distinguish is considered, the phase noise of a laser in the optical transmitter and the phase noise in the optical receiver are firstly distinguished, and the compensation operation of the phase noise of the optical receiver is further performed on the basis of the distinction, so that the balanced enhanced noise in the optical receiver is suppressed, and the performance of an optical fiber communication system is improved.
Description
Technical Field
The present invention relates to the technical field of coherent optical communication and signal processing, and more particularly, to a method and system for suppressing balanced phase noise in optical fiber communication.
Background
At present, coherent optical transmission is widely used in an optical fiber communication network, and the emergence of coherent transmission changes the development of an optical transmission network, and during coherent optical communication, an optical transmitter modulates a signal onto an optical carrier wave in an external modulation mode for transmission. When the signal light transmission reaches the optical receiver, the signal light is firstly in coherent coupling with a local oscillator light signal and then detected by the optical receiver.
The Digital Signal Processing (DSP) introduced by coherent transmission becomes a key driving factor for increasing the capacity of metro and long haul WDM networks, "coherent" is also achieved by the estimation and compensation of phase noise by the Digital Signal Processing (DSP) in the optical receiver, and is therefore also referred to as digital coherent. In addition, the DSP in the optical receiver needs to perform other Equalization functions, which mainly aims at optical fiber dispersion, and both the optical transmitter and the optical receiver include lasers, which generate phase noise, and the laser phase noise is converted into extra noise in the dispersion compensation process, which causes system performance degradation, and is called Equalization-enhanced phase noise (EEPN). Also in few-mode fiber optic communication systems, the optical receiver needs to use multiple-input multiple-output (MIMO) demultiplexing techniques to recover the optical transmission data in multiple modes. In the MIMO equalization process, laser phase noise can also generate equalization enhancement phase noise.
In the prior art, a coherent optical transmission system is disclosed, in which a data signal processing unit is provided in an optical signal receiving device, the digital signal processing unit includes a self-heterodyne frequency noise cancellation module and a phase noise compensation module, wherein the phase noise compensation module cancels phase noise of a signal by using a phase compensation algorithm, thereby ensuring the performance of the whole coherent optical transmission system, but it is worth mentioning that conventional phase noise generally only considers laser phase noise, wherein an equalization enhancement phase noise EEPN is the phase noise of a local laser in an optical receiver, while laser phase noise in an optical transmitter generally does not contribute to EEPN, but during digital coherent reception, the optical receiver phase noise (contributing to EEPN) and optical transmitter phase noise are generally indistinguishable, therefore, how to distinguish and suppress the equalization enhancement phase noise and the transmitter phase noise, it is a problem to be overcome for those skilled in the art.
Disclosure of Invention
In order to solve the problem of how to distinguish the balanced enhanced phase noise from the transmitter phase noise and inhibit the balanced enhanced phase noise in a coherent optical transmission system, the invention provides a method and a system for inhibiting the balanced enhanced phase noise in optical fiber communication.
In order to achieve the technical effects, the technical scheme of the invention is as follows:
a method of suppressing equalization-enhanced phase noise in fiber optic communications, the method comprising the steps of:
s1, generating a conjugate dual carrier through an optical transmitter, and carrying out optical modulation on each subcarrier in the conjugate dual carrier so as to load and transmit data information to an optical receiver;
s2, transmitting the modulated subcarrier to an optical receiver, and performing digital signal processing in the optical receiver through a DSP (digital signal processor) to obtain phase noise of a laser in an optical transmitter and phase noise in the optical receiver;
s3, performing frequency offset compensation in the optical receiver based on the phase noise obtained in the step S2 to obtain a conjugate dual-carrier signal after frequency offset compensation;
s4, carrying out dispersion compensation on the conjugated double-carrier signal obtained in the step S3, generating balanced enhanced noise in the dispersion compensation process, and obtaining a conjugated double-carrier signal containing the balanced enhanced noise after dispersion compensation;
s5, carrying out phase estimation on the conjugated double-carrier signal obtained in the step S4 to obtain the phase of each subcarrier in the conjugated double-carrier;
s6, separating the phase noise of the laser in the optical transmitter from the phase noise in the optical receiver by using the phase of the subcarrier obtained in the step S5 to obtain the distinguishing representation of the phase noise of the laser in the optical transmitter and the phase noise in the optical receiver;
and S7, carrying out phase compensation on the conjugate dual-carrier signal subjected to frequency offset compensation through digital information processing, and then carrying out dispersion compensation to inhibit balance enhanced noise in the optical receiver.
In the technical scheme, a conjugate dual carrier generated in an optical transmitter is used as a carrier, signal data information of the optical transmitter is transmitted to an optical receiver by means of external modulation, the optical receiver performs digital signal processing through a DSP (digital signal processor), the obtained laser phase noise can be converted into extra noise in the dispersion compensation process, namely, balanced enhanced noise, and the problem that the balanced enhanced noise and the laser phase noise in the optical transmitter are difficult to distinguish is considered.
Preferably, when only equalization-enhancing phase noise is considered, an optical carrier is conventionally transmitted between an optical transmitter and an optical carrier receiver, where the optical carrier of the optical transmitter and the optical carrier of the optical receiver are respectively expressed as:
wherein ,ATRepresents an optical carrier of an optical transmitter; a. theRWhich represents the optical carrier of the optical receiver,
respectively representing the phase noise of a laser of a transmitter and the phase noise of a laser in a receiver; the data information transmitted in the optical transmitter is marked as S, and the signals received after the optical-electric conversion in the optical receiver satisfy the following conditions:
where h represents the time domain impulse response of the fiber dispersion,
for convolution operations, the order of the terms cannot be interchanged.
In this case, the signal received after the optical-electrical conversion in the optical receiver is subsequently subjected to dispersion compensation, which produces additional equalization-enhancing phase noise.
Preferably, in step S1, the optical transmitter generates a conjugated dual carrier based on the four-wave mixing effect, the conjugated dual carrier being expressed as:
wherein ,AT1Representing a first subcarrier in the conjugated dual carrier;
representing the phase noise of the laser in the optical transmitter; a. theT2Representing a second subcarrier in the conjugated dual carrier; omegaΔRepresenting angular frequency, between a first subcarrier and a second subcarrierAngular frequency interval 2 omegaΔAnd the phases of the first subcarrier and the second subcarrier satisfy a conjugate relation.
Preferably, in step S2, it is provided that the single laser is used in the optical receiver to simultaneously detect the conjugated dual carrier signal, the phase noise of the laser in the optical transmitter does not contribute to the equalization enhancement phase noise, the data information transmitted in the optical transmitter is still denoted as S, and the phase part of the laser in the optical receiver is denoted as S
wherein ,
representing the phase noise of the laser in the optical transmitter.
Preferably, the conjugate dual carrier signals after the frequency offset compensation in the optical receiver in step S3 are respectively expressed as:
wherein ,R1Representing the first subcarrier signal after frequency offset compensation; r2Representing the frequency offset compensated second subcarrier signal.
Preferably, the pair R of step S41And R2When dispersion compensation is performed, R1、R2Inverse h of time domain impulse response h of fiber dispersion respectively-1Performing convolution operation, in the dispersion compensation process, contributing equalization to enhance noise EEPN in the optical receiver, and obtaining the conjugate dual-carrier signals after dispersion compensation, which are respectively expressed as:
wherein ,
representing a first sub-carrier signal in the dispersion compensated conjugate dual carrier signal;
representing a second subcarrier signal in the dispersion compensated conjugate dual carrier signal; EEPN represents equalization enhancing noise.
Preferably, in step S5, combining
And
based on digital signal processing pairs
And
and performing phase estimation, wherein the phase of each subcarrier in the conjugate dual-carrier satisfies the following conditions:
wherein ,Φ1Indicating the phase of the first subcarrier in the conjugate dual carrier after phase estimation based on digital signal processing; phi2Indicating the phase of the second subcarrier in the conjugate dual carrier after phase estimation based on digital signal processing;
the process of separating the phase noise of the laser in the optical transmitter from the phase noise in the optical receiver using the phase of the subcarrier obtained in step S5 satisfies:
wherein ,
representing the phase noise of the laser in the optical transmitter;
which represents the phase noise of the laser in the optical transmitter, i.e. the equalization enhancement noise.
Preferably, in step S7, the separated conjugate dual-carrier signal after the frequency offset compensation of S3 is processed by digital information before phase compensation is performed on the conjugate dual-carrier signal
Are each introduced into R1And R2Is obtained R which distinguishes phase noise of a laser in an optical transmitter from phase noise in an optical receiver1And R2Expressed as:
r is to be1And R2Are all multiplied by
Obtaining a phase compensated signal:
wherein ,R11Representing a first subcarrier signal after frequency offset compensation and then phase compensation; r23Representing a second subcarrier signal after the frequency offset compensation and then the phase compensation;
after phase compensation, for R11And R22When dispersion compensation is performed, R11、R22Inverse h of time domain impulse response h of fiber dispersion respectively-1Performing convolution operation to offset dispersion, and obtaining a final signal inhibiting the equalization enhancement noise EEPN:
wherein ,
a first subcarrier signal representing suppressed equalization enhancement noise, EEPN;
the second subcarrier signal of the equalization enhancement noise EEPN is suppressed.
The invention also discloses a system for suppressing balanced enhanced phase noise in optical fiber communication, which comprises:
an optical transmitter for generating a conjugate dual carrier;
the optical modulation module is used for modulating each subcarrier in the conjugated dual-carrier so that the conjugated dual-carrier is loaded with transmission data information and transmitted to the optical receiver;
the optical receiver is provided with a Digital Signal Processor (DSP) and is used for receiving the modulated conjugate dual carrier and carrying out digital signal processing through the DSP to obtain phase noise of a laser in the optical transmitter and phase noise in the optical receiver;
the frequency offset compensation module is arranged in the DSP and used for carrying out frequency offset compensation on the conjugate dual-carrier in the optical receiver to obtain a conjugate dual-carrier signal after the frequency offset compensation;
the first dispersion compensation module is arranged in the DSP, performs dispersion compensation on the conjugate dual-carrier signal generated by the frequency offset compensation module after frequency offset compensation, generates balanced enhanced noise in the dispersion compensation process, obtains the conjugate dual-carrier signal containing the balanced enhanced noise after the dispersion compensation, and transmits the conjugate dual-carrier signal to the phase estimation module;
the phase estimation module is arranged in the Digital Signal Processor (DSP), performs phase estimation on the conjugated double-carrier signal transmitted by the first dispersion compensation module to obtain the phase of each subcarrier in the conjugated double-carrier and transmits the phase to the noise separation module;
the noise separation module is arranged in the DSP, separates the phase noise of the laser in the optical transmitter from the phase noise in the optical receiver by utilizing the phase of each subcarrier transmitted by the phase estimation module to obtain the phase noise of the laser in the optical transmitter and the phase noise in the optical receiver after being distinguished, and transmits the phase noise to the phase compensation module;
the phase compensation module is arranged in the digital signal processor DSP, performs phase compensation on the conjugate dual-carrier signal after frequency offset compensation based on the separated phase noise of the laser in the optical transmitter and the phase noise in the optical receiver, and transmits the conjugate dual-carrier signal to the second dispersion compensation module;
and the second dispersion compensation module is arranged in the digital signal processor DSP and is used for carrying out dispersion compensation on the conjugated double-carrier signal after phase compensation and inhibiting balanced enhanced noise in the optical receiver.
Preferably, the optical transmitter generates the conjugate dual carrier based on a four-wave mixing effect.
Compared with the prior art, the technical scheme of the invention has the beneficial effects that:
the invention provides a method and a system for inhibiting balanced enhanced phase noise in optical fiber communication, wherein a conjugate dual carrier generated in an optical transmitter is used as a carrier, signal data information of the optical transmitter is transmitted to an optical receiver by means of external modulation, the optical receiver performs digital signal processing through a DSP (digital signal processor), the obtained laser phase noise can be converted into extra noise in the dispersion compensation process, namely balanced enhanced noise, and the problem that the balanced enhanced noise and the laser phase noise in the optical transmitter are difficult to distinguish is considered.
Drawings
Fig. 1 is a flowchart of a method for suppressing balanced phase noise in optical fiber communication according to embodiment 1 of the present invention;
fig. 2 is a system configuration diagram for suppressing equalization-enhanced phase noise in optical fiber communication according to embodiment 3 of the present invention.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent;
for better illustration of the present embodiment, certain parts of the drawings may be omitted, enlarged or reduced, and do not represent actual dimensions;
it will be understood by those skilled in the art that certain well-known descriptions of the figures may be omitted.
The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent;
the technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
Example 1
When only equalization-enhancing phase noise is considered, an optical carrier is conventionally transmitted between an optical transmitter and an optical carrier receiver, and the optical carrier of the optical transmitter and the optical carrier of the optical receiver are respectively represented as:
wherein ,ATRepresents an optical carrier of an optical transmitter; a. theRWhich represents the optical carrier of the optical receiver,
respectively representing the phase noise of a laser of a transmitter and the phase noise of a laser in a receiver; data information transmitted in an optical transmitter is recorded as S, when an optical pulse signal is transmitted through a long-distance optical fiber, different frequency components or different mode components of the optical signal (pulse) transmitted in the optical fiber are transmitted at different speeds, signal distortion is inevitably generated after the optical pulse signal reaches a certain distance, namely, a dispersion effect occurs, and after the dispersion effect occurs, signals received after photoelectric conversion in an optical receiver meet the following requirements:
where h represents the time domain impulse response of the fiber dispersion,
for convolution operations, the order of the terms cannot be interchanged.
The signal received after the optical-electrical conversion in the optical receiver will be subjected to dispersion compensation in the following, the dispersion equalizer is a typical dispersion compensation means, the detailed principle is not described here, and the signal subjected to dispersion compensation in the DSP of the optical receiver is:
and after dispersion compensation, phase compensation is carried out, and the process meets the following requirements:
in the above formula, due to the convolution operation, the order of the items cannot be exchanged. Since the above process does not take into account other noise, ideally, one should get
However, it can be seen from the above formula that it is not obtained
Instead, the process generates additional equalization-enhanced phase noise EEPN, which is noise related to the phase noise of the laser in the optical receiver, and degrades the performance of the optical fiber communication system, and it can be seen from the formula that it can be compensated and suppressed, but in the digital coherent reception process, the optical receiver phase noise (contributing EEPN) and the optical transmitter phase noise are usually indistinguishable, for this reason, in this embodiment, first of all, with distinction as a premise, a method for suppressing equalization-enhanced phase noise in optical fiber communication is proposed by means of the relationship of conjugate dual carrier phase conjugate and the advantage of conjugate dual carrier, and a specific flowchart is shown in fig. 1, and the method includes the following steps:
s1, generating a conjugate dual carrier through an optical transmitter, and carrying out optical modulation on each subcarrier in the conjugate dual carrier so as to load and transmit data information to an optical receiver;
s2, transmitting the modulated subcarrier to an optical receiver, and performing digital signal processing in the optical receiver through a DSP (digital signal processor) to obtain phase noise of a laser in an optical transmitter and phase noise in the optical receiver;
s3, performing frequency offset compensation in the optical receiver based on the phase noise obtained in the step S2 to obtain a conjugate dual-carrier signal after frequency offset compensation;
s4, carrying out dispersion compensation on the conjugated double-carrier signal obtained in the step S3, generating balanced enhanced noise in the dispersion compensation process, and obtaining a conjugated double-carrier signal containing the balanced enhanced noise after dispersion compensation;
s5, carrying out phase estimation on the conjugated double-carrier signal obtained in the step S4 to obtain the phase of each subcarrier in the conjugated double-carrier;
s6, separating the phase noise of the laser in the optical transmitter from the phase noise in the optical receiver by using the phase of the subcarrier obtained in the step S5 to obtain the distinguishing representation of the phase noise of the laser in the optical transmitter and the phase noise in the optical receiver;
and S7, carrying out phase compensation on the conjugate dual-carrier signal subjected to frequency offset compensation through digital information processing, and then carrying out dispersion compensation to inhibit balance enhanced noise in the optical receiver.
On the whole, a conjugate dual carrier generated in an optical transmitter is used as a carrier, signal data information of the optical transmitter is transmitted to an optical receiver by means of external modulation, the optical receiver performs digital signal processing through a DSP (digital signal processor), the obtained laser phase noise can be converted into extra noise in the dispersion compensation process, namely, balanced enhanced noise, the problem that the balanced enhanced noise and the laser phase noise in the optical transmitter are not easy to distinguish is considered, the phase noise of the laser in the optical transmitter and the phase noise in the optical receiver are distinguished firstly, and the compensation operation of the phase noise of the optical receiver is performed on the basis of the distinction, so that the balanced enhanced noise in the optical receiver is suppressed, and the performance of an optical fiber communication system is improved.
In this embodiment, the optical receiver generates a conjugated dual carrier based on the four-wave mixing effect optical transmitter, where the conjugated dual carrier is expressed as:
wherein ,AT1Representing a first subcarrier in the conjugated dual carrier;
representing the phase noise of the laser in the optical transmitter; a. theT2Representing a second subcarrier in the conjugated dual carrier; omegaΔRepresenting angular frequency, the angular frequency spacing 2 omega between the first and second subcarriersΔAnd the phases of the first subcarrier and the second subcarrier satisfy a conjugate relation.
The method is characterized in that a single laser is used for simultaneously detecting conjugated dual-carrier signals in an optical receiver, the phase noise of the laser in an optical transmitter does not contribute to equalizing and enhancing the phase noise, data information transmitted in the optical transmitter is still marked as S, and the phase part of the laser in the optical receiver is marked as S
wherein ,
representing the phase noise of the laser in the optical transmitter.
Next, frequency offset compensation is performed, the specific process is well known to those skilled in the art, and the conjugated dual carrier signal after frequency offset compensation in the optical receiver is respectively represented as:
wherein ,R1Representing the first subcarrier signal after frequency offset compensation; r2Representing the frequency offset compensated second subcarrier signal.
To R1And R2When dispersion compensation is performed, R1、R2Are respectively provided withInverse h of time domain impulse response h to fiber dispersion-1Performing convolution operation, in the dispersion compensation process, contributing equalization to enhance noise EEPN in the optical receiver, and obtaining the conjugate dual-carrier signals after dispersion compensation, which are respectively expressed as:
wherein ,
representing a first sub-carrier signal in the dispersion compensated conjugate dual carrier signal;
representing a second subcarrier signal in the dispersion compensated conjugate dual carrier signal; EEPN represents equalization enhancing noise.
Bonding of
And
based on digital signal processing pairs
And
and performing phase estimation, wherein the phase of each subcarrier in the conjugate dual-carrier satisfies the following conditions:
wherein ,Φ1Indicating the phase of the first subcarrier in the conjugate dual carrier after phase estimation based on digital signal processing; phi2Indicating the phase of the second subcarrier in the conjugate dual carrier after phase estimation based on digital signal processing;
the process of separating the phase noise of the laser in the optical transmitter from the phase noise in the optical receiver using the phase of the subcarrier obtained in step S5 satisfies:
wherein ,
representing the phase noise of the laser in the optical transmitter;
which represents the phase noise of the laser in the optical transmitter, i.e. the equalization enhancement noise.
In step S7, before phase compensation is performed on the frequency offset compensated conjugate dual carrier signal of step S3 by digital information processing, the separated conjugate dual carrier signal is processed
Are each introduced into R1And R2Is obtained R which distinguishes phase noise of a laser in an optical transmitter from phase noise in an optical receiver1And R2Expressed as:
r is to be1And R2Are all multiplied by
Obtaining a phase compensated signal:
wherein ,R11Representing a first subcarrier signal after frequency offset compensation and then phase compensation; r23Representing a second subcarrier signal after the frequency offset compensation and then the phase compensation;
after phase compensation, for R11And R22When dispersion compensation is performed, R11、R22Inverse h of time domain impulse response h of fiber dispersion respectively-1Performing convolution operation to offset dispersion, and obtaining a final signal inhibiting the equalization enhancement noise EEPN:
wherein ,
a first subcarrier signal representing suppressed equalization enhancement noise, EEPN;
the second subcarrier signal of the equalization enhancement noise EEPN is suppressed, and then the transmission data can be obtained after the signal with the suppression of the equalization enhancement noise is subjected to simple phase equalization.
Example 2
In this embodiment, a system for suppressing balanced phase noise in optical fiber communication is provided, where the system is used to implement the method described in embodiment 1, and referring to fig. 2, the system includes:
an optical transmitter 11 for generating a conjugate dual carrier;
the optical modulation module 12 is configured to modulate each subcarrier in the conjugated dual carrier, so that the conjugated dual carrier loads transmission data information and transmits the transmission data information to the optical receiver; the optical transmitter 12 generates a conjugate dual carrier based on the four-wave mixing effect.
An optical receiver 13, provided with a digital signal processor DSP, where the optical receiver 13 is configured to receive the modulated conjugate dual carrier, and perform digital signal processing through the digital signal processor DSP to obtain phase noise of the laser in the optical transmitter 11 and phase noise in the optical receiver 13;
the frequency offset compensation module 131 is arranged in the digital signal processor DSP, and performs frequency offset compensation on the conjugate dual carrier in the optical receiver 13 to obtain a conjugate dual carrier signal after the frequency offset compensation;
the first dispersion compensation module 132 is disposed in the digital signal processor DSP, performs dispersion compensation on the conjugate dual-carrier signal after the frequency offset compensation generated by the frequency offset compensation module 131, generates balanced enhanced noise in the dispersion compensation process, obtains a conjugate dual-carrier signal containing the balanced enhanced noise after the dispersion compensation, and transmits the conjugate dual-carrier signal to the phase estimation module 133;
a phase estimation module 133, disposed in the digital signal processor DSP, for performing phase estimation on the conjugated dual-carrier signal transmitted by the first dispersion compensation module 132 to obtain a phase of each subcarrier in the conjugated dual-carrier signal, and transmitting the phase to the noise separation module 134;
a noise separation module 134, which is disposed in the digital signal processor DSP, and separates the phase noise of the laser in the optical transmitter 11 from the phase noise in the optical receiver 13 by using the phase of each subcarrier transmitted by the phase estimation module 133, so as to obtain the phase noise of the laser in the optical transmitter 11 and the phase noise in the optical receiver 13 after being distinguished, and transmit the phase noise to the phase compensation module 135;
a phase compensation module 135, which is disposed in the digital signal processor DSP, performs phase compensation on the conjugate dual carrier signal after the frequency offset compensation based on the phase noise of the laser in the optical transmitter 11 and the phase noise in the optical receiver 13, and transmits the phase compensated conjugate dual carrier signal to the second dispersion compensation module 136;
and a second dispersion compensation module 136, disposed in the digital signal processor DSP, for performing dispersion compensation on the phase-compensated conjugate dual-carrier signal to suppress equalization-enhanced noise in the optical receiver 13.
Example 3
In this embodiment, the first dispersion compensation module 132 and the first dispersion compensation module 132 in embodiment 2 both employ dispersion equalizers.
The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent;
it should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. A method for suppressing equalized and enhanced phase noise in optical fiber communications, the method comprising the steps of:
s1, generating a conjugate dual carrier through an optical transmitter, and carrying out optical modulation on each subcarrier in the conjugate dual carrier so as to load and transmit data information to an optical receiver;
s2, transmitting the modulated subcarrier to an optical receiver, and performing digital signal processing in the optical receiver through a DSP (digital signal processor) to obtain phase noise of a laser in an optical transmitter and phase noise in the optical receiver;
s3, performing frequency offset compensation in the optical receiver based on the phase noise obtained in the step S2 to obtain a conjugate dual-carrier signal after frequency offset compensation;
s4, carrying out dispersion compensation on the conjugated double-carrier signal obtained in the step S3, generating balanced enhanced noise in the dispersion compensation process, and obtaining a conjugated double-carrier signal containing the balanced enhanced noise after dispersion compensation;
s5, carrying out phase estimation on the conjugated double-carrier signal obtained in the step S4 to obtain the phase of each subcarrier in the conjugated double-carrier;
s6, separating the phase noise of the laser in the optical transmitter from the phase noise in the optical receiver by using the phase of the subcarrier obtained in the step S5 to obtain the distinguishing representation of the phase noise of the laser in the optical transmitter and the phase noise in the optical receiver;
and S7, carrying out phase compensation on the conjugate dual-carrier signal subjected to frequency offset compensation through digital information processing, and then carrying out dispersion compensation to inhibit balance enhanced noise in the optical receiver.
2. The method of suppressing equalized and enhanced phase noise in optical fiber communication according to claim 1, wherein when only the equalized and enhanced phase noise is considered, an optical carrier is conventionally transmitted between an optical transmitter and an optical carrier receiver, and the optical carrier of the optical transmitter and the optical carrier of the optical receiver are respectively expressed as:
wherein ,ATRepresenting optical carriers of optical transmitters；ARWhich represents the optical carrier of the optical receiver,
respectively representing the phase noise of a laser of a transmitter and the phase noise of a laser in a receiver; the data information transmitted in the optical transmitter is marked as S, and the signals received after the optical-electric conversion in the optical receiver satisfy the following conditions:
where h represents the time domain impulse response of the fiber dispersion,
for convolution operations, the order of the terms cannot be interchanged.
3. The method for suppressing equalized and enhanced phase noise in optical fiber communication according to claim 2, wherein in step S1, a conjugate dual carrier is generated based on a four-wave mixing effect optical transmitter, and the conjugate dual carrier is expressed as:
wherein ,AT1Representing a first subcarrier in the conjugated dual carrier;
representing the phase noise of the laser in the optical transmitter; a. theT2Representing a second subcarrier in the conjugated dual carrier; omegaΔRepresenting angular frequency, the angular frequency spacing 2 omega between the first and second subcarriersΔAnd the phases of the first subcarrier and the second subcarrier satisfy a conjugate relation.
4. The method for suppressing equalizer-enhanced phase noise in optical fiber communication according to claim 3, wherein in step S2, a single laser is used in the optical receiver to simultaneously detect the conjugated dual-carrier signal, the phase noise of the laser in the optical transmitter does not contribute to the equalizer-enhanced phase noise, the data information transmitted in the optical transmitter is still denoted as S, and the phase portion of the laser in the optical receiver is denoted as S
wherein ,
representing the phase noise of the laser in the optical transmitter.
5. The method of claim 4, wherein the conjugate dual carrier signals after frequency offset compensation in the optical receiver in step S3 are respectively represented as:
wherein ,R1Representing the first subcarrier signal after frequency offset compensation; r2Representing the frequency offset compensated second subcarrier signal.
6. The method for suppressing equalized and enhanced phase noise in optical fiber communication according to claim 5, wherein the pair R of step S41And R2When dispersion compensation is performed, R1、R2Respectively with lightInverse h of time domain impulse response h of fiber dispersion-1Performing convolution operation, in the dispersion compensation process, contributing equalization to enhance noise EEPN in the optical receiver, and obtaining the conjugate dual-carrier signals after dispersion compensation, which are respectively expressed as:
wherein ,
representing a first sub-carrier signal in the dispersion compensated conjugate dual carrier signal;
representing a second subcarrier signal in the dispersion compensated conjugate dual carrier signal; EEPN represents equalization enhancing noise.
7. The method for suppressing equalized and enhanced phase noise in optical fiber communication according to claim 6, wherein in step S5, the combination
And
based on digital signal processing pairs
And
and performing phase estimation, wherein the phase of each subcarrier in the conjugate dual-carrier satisfies the following conditions:
wherein ,Φ1Indicating the phase of the first subcarrier in the conjugate dual carrier after phase estimation based on digital signal processing; phi2Indicating the phase of the second subcarrier in the conjugate dual carrier after phase estimation based on digital signal processing;
the process of separating the phase noise of the laser in the optical transmitter from the phase noise in the optical receiver using the phase of the subcarrier obtained in step S5 satisfies:
wherein ,
representing the phase noise of the laser in the optical transmitter;
which represents the phase noise of the laser in the optical transmitter, i.e. the equalization enhancement noise.
8. The method of claim 7, wherein in step S7, the separated conjugate dual carrier signal after frequency offset compensation is processed by digital information processing before phase compensation is performed on the frequency offset compensated conjugate dual carrier signal of S3
/2 brings into R respectively1And R2Is obtained R which distinguishes phase noise of a laser in an optical transmitter from phase noise in an optical receiver1And R2Expressed as:
r is to be1And R2Are all multiplied by
Obtaining a phase compensated signal:
wherein ,R11Representing a first subcarrier signal after frequency offset compensation and then phase compensation; r23Representing a second subcarrier signal after the frequency offset compensation and then the phase compensation;
after phase compensation, for R11And R22When dispersion compensation is performed, R11、R22Inverse h of time domain impulse response h of fiber dispersion respectively-1Performing convolution operation to offset dispersion, and obtaining a final signal inhibiting the equalization enhancement noise EEPN:
wherein ,
a first subcarrier signal representing suppressed equalization enhancement noise, EEPN;
the second subcarrier signal of the equalization enhancement noise EEPN is suppressed.
9. A system for suppressing equalization-enhanced phase noise in fiber optic communications, the system comprising:
an optical transmitter for generating a conjugate dual carrier;
the optical modulation module is used for modulating each subcarrier in the conjugated dual-carrier so that the conjugated dual-carrier is loaded with transmission data information and transmitted to the optical receiver;
the optical receiver is provided with a Digital Signal Processor (DSP) and is used for receiving the modulated conjugate dual carrier and carrying out digital signal processing through the DSP to obtain phase noise of a laser in the optical transmitter and phase noise in the optical receiver;
the frequency offset compensation module is arranged in the DSP and used for carrying out frequency offset compensation on the conjugate dual-carrier in the optical receiver to obtain a conjugate dual-carrier signal after the frequency offset compensation;
the first dispersion compensation module is arranged in the DSP, performs dispersion compensation on the conjugate dual-carrier signal generated by the frequency offset compensation module after frequency offset compensation, generates balanced enhanced noise in the dispersion compensation process, obtains the conjugate dual-carrier signal containing the balanced enhanced noise after the dispersion compensation, and transmits the conjugate dual-carrier signal to the phase estimation module;
the phase estimation module is arranged in the Digital Signal Processor (DSP), performs phase estimation on the conjugated double-carrier signal transmitted by the first dispersion compensation module to obtain the phase of each subcarrier in the conjugated double-carrier and transmits the phase to the noise separation module;
the noise separation module is arranged in the DSP, separates the phase noise of the laser in the optical transmitter from the phase noise in the optical receiver by utilizing the phase of each subcarrier transmitted by the phase estimation module to obtain the phase noise of the laser in the optical transmitter and the phase noise in the optical receiver after being distinguished, and transmits the phase noise to the phase compensation module;
the phase compensation module is arranged in the digital signal processor DSP, performs phase compensation on the conjugate dual-carrier signal after frequency offset compensation based on the separated phase noise of the laser in the optical transmitter and the phase noise in the optical receiver, and transmits the conjugate dual-carrier signal to the second dispersion compensation module;
and the second dispersion compensation module is arranged in the digital signal processor DSP and is used for carrying out dispersion compensation on the conjugated double-carrier signal after phase compensation and inhibiting balanced enhanced noise in the optical receiver.
10. The system for suppressing equalized and enhanced phase noise in optical fiber communication according to claim 9, wherein the optical transmitter generates the conjugate dual carrier based on a four-wave mixing effect.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101808059A (en) * | 2009-02-13 | 2010-08-18 | 瑞昱半导体股份有限公司 | Single carrier/multi-carrier share receiver |
| CN108282227A (en) * | 2018-01-18 | 2018-07-13 | 清华大学 | A kind of steady phase partitioning system in quadruple signal optical fibre arbitrary point based on phase conjugation |
| CN108476187A (en) * | 2016-01-14 | 2018-08-31 | 英特尔公司 | The devices, systems, and methods communicated according to transmission space-frequency diversity scheme |
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| CN101808059A (en) * | 2009-02-13 | 2010-08-18 | 瑞昱半导体股份有限公司 | Single carrier/multi-carrier share receiver |
| CN108476187A (en) * | 2016-01-14 | 2018-08-31 | 英特尔公司 | The devices, systems, and methods communicated according to transmission space-frequency diversity scheme |
| CN108282227A (en) * | 2018-01-18 | 2018-07-13 | 清华大学 | A kind of steady phase partitioning system in quadruple signal optical fibre arbitrary point based on phase conjugation |
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