CN116032373A

CN116032373A - Coherent optical module and preparation process thereof

Info

Publication number: CN116032373A
Application number: CN202310023878.6A
Authority: CN
Inventors: 陈享郭; 苏明; 廖斐; 王峻岭; 代等
Original assignee: SHENZHEN OPWAY COMMUNICATION CO Ltd
Current assignee: SHENZHEN OPWAY COMMUNICATION CO Ltd
Priority date: 2023-01-09
Filing date: 2023-01-09
Publication date: 2023-04-28
Anticipated expiration: 2043-01-09
Also published as: CN116032373B

Abstract

The invention provides a coherent light module and a preparation process thereof, comprising the following steps: the transmission end electro-optic modulation group respectively generates high-net baud rate QAM-16 signals through a dual-polarization IQ electro-optic modulation platform; the polarization beam splitting frequency-division coupling group is used for coupling two groups of high-bit-rate optical signals to two different polarization states of the optical fiber through a first polarization rotating beam splitter/combiner PRS; a high-speed coherent signal transmission group for carrying out coherent optical signal transmission of single fiber 400G; the receiving end polarization beam splitting group splits the high-speed coherent transmission signal of the polarization beam splitting single fiber 400G; the beam splitting signal light interference group is used for respectively interfering the two groups of polarized beam splitting signals with local oscillation light; the photoelectric balance analog-to-digital conversion group is used for inputting two groups of local oscillator coherent signals into the photoelectric balance detector and performing analog-to-digital conversion; and the signal processing, decoding and converting group realizes the decoding output of signals through the digital signal processing DSP to obtain 400G coherent light conversion output signals.

Description

Coherent optical module and preparation process thereof

Technical Field

The invention relates to the technical field of intelligent integration of coherent optical communication, in particular to a coherent optical module and a preparation process thereof.

Background

At present, the complex adjustment and measurement difficulty of the production process of the high-speed high-frequency coherent optical module is high, the optical module software relates to configuration and adjustment work of a large number of parameters, the production efficiency is low purely by ordinary production, and the yield is difficult to guarantee; the technical problems to be solved are as follows: comprising the following steps: how PAM4 modulation achieves long-range transmission by implementing the same link budget through forward error correction technology FEC technology; how to implement by a combined application of multiple technologies; the problems of how to generate high-net-baud-rate QAM-16 signals to obtain two groups of high-bit-rate optical signals, how to couple the two groups of high-bit-rate optical signals respectively, how to transmit coherent optical signals of single fiber 400G, how to obtain two groups of polarized beam splitting signals, how to obtain two groups of local oscillator coherent signals, how to obtain photoelectric balance analog-digital conversion signals, how to decode and output the signals, obtain coherent optical conversion output signals and the like remain to be solved; therefore, there is a need for a coherent optical module and a manufacturing process thereof that at least partially solve the problems of the prior art.

Disclosure of Invention

A series of concepts in simplified form are introduced in the summary section, which will be described in further detail in the detailed description section; the summary of the invention is not intended to define the key features and essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

To at least partially solve the above problems, the present invention provides a coherent optical module, including:

the transmission end electro-optic modulation group respectively generates high-net-baud-rate QAM-16 signals through a dual-polarization IQ electro-optic modulation platform at the signal transmission end to obtain two groups of high-bit-rate optical signals;

the polarization beam splitting frequency-division coupling group is used for coupling two groups of high-bit-rate optical signals to two different polarization states of the optical fiber through a first polarization rotating beam splitter/combiner PRS;

the high-speed coherent signal transmission group is used for carrying out coherent optical signal transmission of the single fiber 400G according to two different polarization states to obtain a polarized beam-splitting single fiber 400G high-speed coherent transmission signal;

the receiving end polarization beam splitting group splits the high-speed coherent transmission signal of the polarization beam splitting single fiber 400G through a second polarization rotation beam splitting and combining device PRS at the signal receiving end to obtain two groups of polarization beam splitting signals;

the beam splitting signal light interference group is used for respectively interfering the two groups of polarized beam splitting signals with local oscillation light to obtain two groups of local oscillation coherent signals;

the photoelectric balance analog-to-digital conversion group is used for inputting two groups of local oscillator coherent signals into the photoelectric balance detector and performing analog-to-digital conversion to obtain photoelectric balance analog-to-digital conversion signals;

And the signal processing, decoding and converting group is used for realizing the decoding output of the signal through a digital signal processing DSP according to the photoelectric balance analog-to-digital conversion signal to obtain a 400G coherent light conversion output signal.

Preferably, the transmission-side electro-optical modulation group includes:

the integrated high-order signal chip unit supports multi-device integration and high-order signal modulation through a thin film lithium niobate modulator chip; the thin film lithium niobate modulator chip consists of four groups of Mach-Zehnder intensity modulators MZM;

the thin film lithium niobate platform unit is used for forming an upper IQ modulator and a lower IQ modulator by every two groups of Mach-Zehnder intensity modulators MZM to obtain a thin film lithium niobate platform of the dual-polarization IQ electro-optic modulator to form a dual-polarization IQ electro-optic modulation platform;

and the four-level loading signal unit can obtain a high-net-baud-rate QAM-16 signal by loading PAM-4 signals containing four levels on each MZM, and two groups of high-bit-rate optical signals are obtained.

Preferably, the polarization beam splitting frequency-division coupling group includes:

a multi-path polarization rotation setting unit, setting a multi-path polarization rotation beam splitting and combining device PRS with the bandwidth of 130nm on a film lithium niobate platform, and obtaining a first polarization rotation beam splitting and combining device PRS and a second polarization rotation beam splitting and combining device PRS;

And the optical signal coupling polarization state unit is used for respectively coupling two groups of optical signals with the bit rate of 200Gbit/s onto two different polarization states of the optical fiber through the first polarization rotating beam splitter/combiner PRS to obtain a first polarization state coupling signal and a second polarization state coupling signal.

Preferably, the high-speed coherent signal transmission group includes:

the polarization state coupling signal combining unit combines the first polarization state coupling signal and the second polarization state coupling signal into one waveguide fiber through the first polarization rotation beam splitting and combining device PRS;

and the single-fiber 400G coherent signal transmission unit is used for carrying out coherent signal transmission of the single fiber 400G through a waveguide fiber to obtain a polarized beam-splitting single-fiber 400G high-speed coherent light transmission signal.

Preferably, the receiving-end polarization beam splitting group includes:

a receiving end polarization rotation unit, at the signal receiving end, a second polarization rotation beam splitter-combiner PRS is arranged;

the coherent transmission signal beam splitting unit splits the high-speed coherent transmission signal of the polarized beam splitting single fiber 400G through a second polarized rotating beam splitting and combining device PRS;

and the receiving polarization signal conveying unit is used for obtaining a first receiving polarization beam splitting signal and a second receiving polarization beam splitting signal by splitting the polarization beam splitting single-fiber 400G high-speed coherent transmission signal.

Preferably, the beam splitting signal present optical interference group includes:

the local oscillation laser source wavelength setting unit is used for determining the local oscillation laser source wavelength according to a homodyne receiving down-conversion mode; setting the wavelength of the local oscillator laser to be the same as the wavelength of the emitting end laser, setting the wavelength of a local oscillator laser source, and performing homodyne receiving and down-conversion receiving;

the polarization beam splitting coherent local oscillation interference unit performs coherent local oscillation interference on the first received polarization beam splitting signal and the second received polarization beam splitting signal and local oscillation light respectively through homodyne receiving down-conversion receiving;

the local oscillator coherent signal acquisition unit acquires a first polarization beam splitting local oscillator coherent signal and a second polarization beam splitting local oscillator coherent signal through coherent local oscillator interference.

Preferably, the photoelectric balance analog-to-digital conversion group includes:

the photoelectric balance detection unit is used for setting a photoelectric balance detector through beat frequency of the local oscillator light source and the received light signal through the optical mixer;

the coherent detection amplitude-phase maintaining unit inputs the first received polarized beam-splitting coherent signal and the second received polarized beam-splitting coherent signal into the photoelectric balance detector, and the photoelectric balance detector carries out coherent detection; the amplitude and phase information carried in the signal optical domain is completely reserved in the electric signal after photoelectric conversion; processing by a front end orthogonalization and normalization module and a clock synchronization module; adopting a single-layer pure butterfly structure, forming a single-layer butterfly compensation module by 4 adaptive finite impulse corresponding FIR filters, and compensating chromatic dispersion and polarization mode chromatic dispersion;

The clock synchronous analog-to-digital conversion unit obtains two orthogonal in-phase components I and orthogonal components Q of the OFDM signal after photoelectric conversion of the balanced receiver; the two paths of amplitude and phase mismatch of the in-phase component I and the quadrature component Q in two polarization directions are compensated and corrected, and the sampling clocks of the receiving and transmitting ends are completely synchronous; analog-to-digital conversion is carried out, A/D conversion is carried out by a real-time oscilloscope, and digital signals after the A/D conversion are stored for offline processing; and obtaining a photoelectric balance analog-to-digital conversion signal.

Preferably, the signal processing decoding conversion group includes:

the double-layer digital signal processing unit adopts a double-layer structure digital signal processing DSP to realize the decoding output of signals according to photoelectric balance analog-to-digital conversion signals;

the digital signal differential operation unit, the double-layer structure digital signal processing DSP includes: a first layer digital signal processing DSP and a second layer digital signal processing DSP; the first layer digital signal processing DSP and the second layer digital signal processing DSP respectively run at different speeds, the chromatic dispersion is approximately unchanged under millisecond level, the polarization mode chromatic dispersion is changed with time, and the tap coefficient of the filter does not need to be updated frequently in the chromatic dispersion compensation process;

the loss compensation estimation output unit compensates the loss irrelevant to polarization through the first layer digital signal processing DSP; performing polarization dependent loss compensation on the second layer digital signal processing DSP; polarization dependent loss compensation includes: polarization rotation compensation and polarization mode dispersion compensation; the loss is estimated and compensated by a digital signal processing demodulation module and a digital signal processing algorithm, so that the regeneration and recovery of the original transmitting signal are completed; a 400G coherent light converted output signal is obtained.

Preferably, the digital signal processing demodulation module includes:

the serial-parallel frequency offset compensation subunit converts the serial-parallel frequency offset compensation subunit into parallel signals; determining an OFDM signal start length through symbol synchronization; estimating and compensating the frequency offset of the received OFDM signal;

a time-frequency transformation estimation equalization subunit, which changes the signal from the time domain to the frequency domain through fast Fourier transformation; extracting training sequences for channel estimation and completing channel estimation and channel equalization;

the parallel-serial conversion bit calculation subunit extracts pilot frequency and realizes estimation and compensation of phase noise; the signal is converted in parallel and serial and the error rate is calculated in comparison with the original bit.

A preparation process of a coherent optical module comprises the following steps:

s100, respectively generating high-net-baud-rate QAM-16 signals at a signal transmission end through a dual-polarization IQ (in-phase-quadrature-phase) electro-optic modulation platform to obtain two groups of high-bit-rate optical signals;

s200, respectively coupling two groups of high-bit-rate optical signals to two different polarization states of an optical fiber through a first polarization rotation beam splitter (PRS);

s300, carrying out coherent optical signal transmission of single fiber 400G according to two different polarization states, and obtaining a polarized beam splitting single fiber 400G high-speed coherent transmission signal;

S400, at a signal receiving end, splitting the polarized beam splitting single fiber 400G high-speed coherent transmission signal through a second polarized rotary beam splitting and combining device PRS to obtain two groups of polarized beam splitting signals;

s500, respectively interfering the two groups of polarized beam splitting signals with local oscillation light to obtain two groups of local oscillation coherent signals;

s600, inputting two groups of local oscillator coherent signals into a photoelectric balance detector and performing analog-to-digital conversion to obtain photoelectric balance analog-to-digital conversion signals;

s700, according to the photoelectric balance analog-to-digital conversion signal, decoding output of the signal is achieved through a digital signal processing DSP, and a 400G coherent light conversion output signal is obtained; the module chip equalizes the high-speed signals to the transmitting end and the receiving end; the transmitting end and the receiving end balance and compensate the loss of data when transmitting in a lossy link, carry out high-speed link design and loss compensation, and obtain an open eye diagram and a BER bit error rate which accords with the specification at the receiving end; synchronously developing an intelligent automatic production debugging tool and automatic production debugging software, and intelligently and automatically carrying out configuration debugging on a large number of parameters of the optical module software; and (5) producing and adjusting the 400G coherent optical module to realize preparation.

Compared with the prior art, the invention at least comprises the following beneficial effects:

The invention provides a coherent optical module and a preparation process thereof.A transmission end electro-optic modulation group is used for respectively generating high-net-baud-rate QAM-16 signals through a dual-polarization IQ electro-optic modulation platform at a signal transmission end to obtain two groups of high-bit-rate optical signals; the polarization beam splitting frequency-division coupling group is used for coupling two groups of high-bit-rate optical signals to two different polarization states of the optical fiber through a first polarization rotating beam splitter/combiner PRS; the high-speed coherent signal transmission group is used for carrying out coherent optical signal transmission of the single fiber 400G according to two different polarization states to obtain a polarized beam-splitting single fiber 400G high-speed coherent transmission signal; the receiving end polarization beam splitting group splits the high-speed coherent transmission signal of the polarization beam splitting single fiber 400G through a second polarization rotation beam splitting and combining device PRS at the signal receiving end to obtain two groups of polarization beam splitting signals; the beam splitting signal light interference group is used for respectively interfering the two groups of polarized beam splitting signals with local oscillation light to obtain two groups of local oscillation coherent signals; the photoelectric balance analog-to-digital conversion group is used for inputting two groups of local oscillator coherent signals into the photoelectric balance detector and performing analog-to-digital conversion to obtain photoelectric balance analog-to-digital conversion signals; the signal processing, decoding and converting group is used for realizing the decoding output of the signals through a digital signal processing DSP according to the photoelectric balance analog-to-digital conversion signals to obtain 400G coherent light conversion output signals; the method has the advantages that great convenience is brought to the realization of digital signal processing, the dispersion is approximately unchanged in millisecond order, and the polarization mode dispersion is changed with time, so that tap coefficients of a filter do not need to be updated frequently in the dispersion compensation process; the error rate of the system can be effectively reduced, the transmission distance can be prolonged, and the aim of reducing the cost of the system can be realized with small redundancy cost; the use of FEC can effectively improve the performance of the system; the realization of the whole system relates to the coding, modulation and post-processing of high-speed photoelectric signals, the practical test and the productization test of the whole optical module system, and the photoelectric system integration of high-performance elements of a module series is realized.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate the invention and together with the embodiments of the invention, serve to explain the invention. In the drawings:

fig. 1 is a diagram of a coherent optical module system according to the present invention.

Fig. 2 is a diagram illustrating an overall structure of a coherent optical module according to an embodiment of the present invention.

Fig. 3 is a diagram of a dual-layer digital signal processing unit according to an embodiment of a coherent optical module according to the present invention.

Fig. 4 is a diagram of a new mode of a 16QAM signal according to another embodiment of a coherent optical module according to the present invention.

Fig. 5 is a diagram illustrating dual-polarization IQ electro-optic modulation according to another embodiment of a coherent optical module according to the present invention.

Detailed Description

The present invention is described in further detail below with reference to the drawings and examples to enable those skilled in the art to practice the same and to refer to the description; as shown in fig. 1 to 5, the present invention provides a coherent optical module including:

The working principle of the technical scheme is as follows: the invention provides a coherent light module, comprising:

the beam splitting signal light interference group is used for respectively interfering the two groups of polarized beam splitting signals with local oscillation light to obtain two groups of local oscillation coherent signals; the local oscillator light is LocalOscillator light;

The signal processing, decoding and converting group is used for realizing the decoding output of the signals through a digital signal processing DSP according to the photoelectric balance analog-to-digital conversion signals to obtain 400G coherent light conversion output signals;

the step of generating the 16QAM signal by the optical device in a new way comprises the steps of: biasing the double balanced MZM to be pi/2, wherein both MZM1 and MZM2 are biased to be 0.6 pi, and driving fluctuation peak value to be 0.8 pi; generating a right-angle 4QAM constellation point through the double-balanced MZM structure; after the 4QAM signal passes through a phase modulator MZM3 set as [0, pi ], a special 8QAM constellation point is generated; finally, generating a 16QAM constellation point under the rotation action of a [0, pi/2 ] phase modulator; firstly, a double-balanced MZM is adopted to generate constellation points in a certain quadrant, and then rotary transformation of the constellation points is realized through a phase modulator, so that the constellation points are distributed in the whole space.

The beneficial effects of the technical scheme are as follows: the invention provides a coherent light module, comprising: the transmission end electro-optic modulation group respectively generates high-net-baud-rate QAM-16 signals through a dual-polarization IQ electro-optic modulation platform at the signal transmission end to obtain two groups of high-bit-rate optical signals; the polarization beam splitting frequency-division coupling group is used for coupling two groups of high-bit-rate optical signals to two different polarization states of the optical fiber through a first polarization rotating beam splitter/combiner PRS; the high-speed coherent signal transmission group is used for carrying out coherent optical signal transmission of the single fiber 400G according to two different polarization states to obtain a polarized beam-splitting single fiber 400G high-speed coherent transmission signal; the receiving end polarization beam splitting group splits the high-speed coherent transmission signal of the polarization beam splitting single fiber 400G through a second polarization rotation beam splitting and combining device PRS at the signal receiving end to obtain two groups of polarization beam splitting signals; the beam splitting signal light interference group is used for respectively interfering the two groups of polarized beam splitting signals with local oscillation light to obtain two groups of local oscillation coherent signals; the photoelectric balance analog-to-digital conversion group is used for inputting two groups of local oscillator coherent signals into the photoelectric balance detector and performing analog-to-digital conversion to obtain photoelectric balance analog-to-digital conversion signals; the signal processing, decoding and converting group is used for realizing the decoding output of the signals through a digital signal processing DSP according to the photoelectric balance analog-to-digital conversion signals to obtain 400G coherent light conversion output signals; the method has the advantages that great convenience is brought to the realization of digital signal processing, the dispersion is approximately unchanged in millisecond order, and the polarization mode dispersion is changed with time, so that tap coefficients of a filter do not need to be updated frequently in the dispersion compensation process; the error rate of the system can be effectively reduced, the transmission distance can be prolonged, and the aim of reducing the cost of the system can be realized with small redundancy cost; the use of FEC can effectively improve the performance of the system; the realization of the whole system relates to the coding, modulation and post-processing of high-speed photoelectric signals, the practical test and the productization test of the whole optical module system, and the photoelectric system integration of high-performance elements of a module series is realized.

In one embodiment, the transmission-side electro-optical modulation group includes:

The working principle of the technical scheme is as follows: the transmission-side electro-optical modulation group comprises:

the thin film lithium niobate platform unit is used for generating pi phase difference between every two groups of Mach-Zehnder intensity modulators MZM through a 90-degree electro-optical phase shifter to obtain an upper IQ modulator group and a lower IQ modulator group to realize IQ modulation; the upper and lower sets of IQ modulators are respectively responsible for data transmission of one polarization state; obtaining a double-polarization IQ electro-optic modulator film lithium niobate platform to form a double-polarization IQ electro-optic modulation platform;

The four-level loading signal unit can obtain high-net-baud-rate QAM-16 signals by loading PAM-4 signals containing four levels on each MZM, and two groups of high-bit-rate optical signals are obtained; the high net baud rate QAM-16 signal comprises: a QAM-16 signal with a net baud rate of 50 Gbaud; acquiring two sets of high bit rate optical signals includes: two sets of 200Gbit/s optical signals;

an OFDM signal generated offline is converted into an analog signal by an analog-to-digital converter, the analog signal is filtered through a low pass filter, an in-phase component I and a quadrature component Q of the signal are amplified by an amplifier and injected into an I/Q modulator to realize quadrature modulation of the optical signal by the in-phase component I and the quadrature component Q; the I/Q modulator consists of 3 double-arm MZM modulators, the two modulators realize the modulation of signals, the 3 rd modulator controls the phase difference of an in-phase component I and a quadrature component Q of the optical modulation, the direct current bias of the two modulators is respectively regulated to ensure that the modulator realizing the modulation of the signals works at a minimum power point, and the 3 rd modulator controlling the phase difference works at a positive intersection point to ensure that pi/2 phase difference exists between the two paths of signals; thus, the optical OFDM signal is obtained after I/Q modulation.

The beneficial effects of the technical scheme are as follows: the transmission-side electro-optical modulation group comprises: the integrated high-order signal chip unit supports multi-device integration and high-order signal modulation through a thin film lithium niobate modulator chip; the thin film lithium niobate modulator chip consists of four groups of Mach-Zehnder intensity modulators MZM; the thin film lithium niobate platform unit is used for generating pi phase difference between every two groups of Mach-Zehnder intensity modulators MZM through a 90-degree electro-optical phase shifter to obtain an upper IQ modulator group and a lower IQ modulator group to realize IQ modulation; the upper and lower sets of IQ modulators are respectively responsible for data transmission of one polarization state; obtaining a double-polarization IQ electro-optic modulator film lithium niobate platform to form a double-polarization IQ electro-optic modulation platform; the four-level loading signal unit can obtain high-net-baud-rate QAM-16 signals by loading PAM-4 signals containing four levels on each MZM, and two groups of high-bit-rate optical signals are obtained; the high net baud rate QAM-16 signal comprises: a QAM-16 signal with a net baud rate of 50 Gbaud; acquiring two sets of high bit rate optical signals includes: two sets of 200Gbit/s optical signals; an OFDM signal generated offline is converted into an analog signal by an analog-to-digital converter, the analog signal is filtered through a low pass filter, an in-phase component I and a quadrature component Q of the signal are amplified by an amplifier and injected into an I/Q modulator to realize quadrature modulation of the optical signal by the in-phase component I and the quadrature component Q; the I/Q modulator consists of 3 double-arm MZM modulators, the two modulators realize the modulation of signals, the 3 rd modulator controls the phase difference of an in-phase component I and a quadrature component Q of the optical modulation, the direct current bias of the two modulators is respectively regulated to ensure that the modulator realizing the modulation of the signals works at a minimum power point, and the 3 rd modulator controlling the phase difference works at a positive intersection point to ensure that pi/2 phase difference exists between the two paths of signals; thus, the optical OFDM signal is obtained after I/Q modulation.

In one embodiment, the polarization beam splitting frequency-division coupling group includes:

The working principle of the technical scheme is as follows: the polarization beam splitting frequency-division coupling group comprises:

the optical signal coupling polarization state unit is used for respectively coupling two groups of optical signals with the bit rate of 200Gbit/s to two different polarization states of the optical fiber through the first polarization rotating beam splitter/combiner PRS to obtain a first polarization state coupling signal and a second polarization state coupling signal;

mapping original signals to optical carrier parameters based on serial-parallel configuration of MZM and PM through optical modulation of multidimensional multi-order signals; comprising the following steps: serial cascade scheme, parallel modulation scheme, and serial-parallel hybrid modulation scheme; the serial concatenation scheme includes: the modulation of the optical signal is finally realized by modulating the signal primary of the input optical field: the parallel modulation scheme includes: mapping of the multi-path binary digital signal to the optical signal is realized by connecting a plurality of MZM modulators in parallel; the serial-parallel hybrid modulation scheme includes: and according to the integration requirement, the modulation from the electric signal to the optical signal is realized by adopting a serial-parallel mixing mode.

The beneficial effects of the technical scheme are as follows: the polarization beam splitting frequency-division coupling group comprises:

In one embodiment, the high-speed coherent signal transmission set includes:

The working principle of the technical scheme is as follows: the high-speed coherent signal transmission group includes:

The beneficial effects of the technical scheme are as follows: the high-speed coherent signal transmission group includes: the polarization state coupling signal combining unit combines the first polarization state coupling signal and the second polarization state coupling signal into one waveguide fiber through the first polarization rotation beam splitting and combining device PRS; and the single-fiber 400G coherent signal transmission unit is used for carrying out coherent signal transmission of the single fiber 400G through a waveguide fiber to obtain a polarized beam-splitting single-fiber 400G high-speed coherent light transmission signal.

In one embodiment, the receiving-end polarization beam splitter group includes:

The working principle of the technical scheme is as follows: the receiving end polarization beam splitting group comprises: a receiving end polarization rotation unit, at the signal receiving end, a second polarization rotation beam splitter-combiner PRS is arranged; the coherent transmission signal beam splitting unit splits the high-speed coherent transmission signal of the polarized beam splitting single fiber 400G through a second polarized rotating beam splitting and combining device PRS; and the receiving polarization signal conveying unit is used for obtaining a first receiving polarization beam splitting signal and a second receiving polarization beam splitting signal by splitting the polarization beam splitting single-fiber 400G high-speed coherent transmission signal.

The beneficial effects of the technical scheme are as follows: a second polarization rotation beam splitter-combiner PRS is arranged at the signal receiving end through a receiving end polarization rotation unit; the coherent transmission signal beam splitting unit splits the high-speed coherent transmission signal of the polarized beam splitting single fiber 400G through a second polarized rotating beam splitting and combining device PRS; and the receiving polarization signal conveying unit is used for obtaining a first receiving polarization beam splitting signal and a second receiving polarization beam splitting signal by splitting the polarization beam splitting single-fiber 400G high-speed coherent transmission signal.

In one embodiment, the beam splitting signal present optical interference group includes:

The working principle of the technical scheme is as follows: the beam splitting signal present optical interference group comprises:

the local oscillator coherent signal acquisition unit acquires a first polarization beam splitting local oscillator coherent signal and a second polarization beam splitting local oscillator coherent signal through coherent local oscillator interference;

calculating a matching correlation value of the local oscillator laser source wavelength and the target wavelength:

/>

Wherein, BHLOD represents the matching correlation value of the local oscillator laser source wavelength and the target wavelength, K represents the total number of the matching wavelengths, i represents the ith matching wavelength, hlo represents the matched local oscillator laser source wavelength, hdb represents the matching target wavelength; and the matching correlation value of the local oscillation laser source wavelength and the target wavelength is calculated, so that the matching correlation of the local oscillation laser source wavelength and the target wavelength is better.

The beneficial effects of the technical scheme are as follows: the beam splitting signal present optical interference group comprises: the local oscillation laser source wavelength setting unit is used for determining the local oscillation laser source wavelength according to a homodyne receiving down-conversion mode; setting the wavelength of the local oscillator laser to be the same as the wavelength of the emitting end laser, setting the wavelength of a local oscillator laser source, and performing homodyne receiving and down-conversion receiving; the polarization beam splitting coherent local oscillation interference unit performs coherent local oscillation interference on the first received polarization beam splitting signal and the second received polarization beam splitting signal and local oscillation light respectively through homodyne receiving down-conversion receiving; the local oscillator coherent signal acquisition unit acquires a first polarization beam splitting local oscillator coherent signal and a second polarization beam splitting local oscillator coherent signal through coherent local oscillator interference;

calculating a matching correlation value of the local oscillator laser source wavelength and the target wavelength: wherein, BHLOD represents the matching correlation value of the local oscillator laser source wavelength and the target wavelength, K represents the total number of the matching wavelengths, i represents the ith matching wavelength, hlo represents the matched local oscillator laser source wavelength, hdb represents the matching target wavelength; and the matching correlation value of the local oscillation laser source wavelength and the target wavelength is calculated, so that the matching correlation of the local oscillation laser source wavelength and the target wavelength is better.

In one embodiment, the photoelectric balance analog-to-digital conversion group includes:

The working principle of the technical scheme is as follows: the photoelectric balance analog-to-digital conversion group includes:

The beneficial effects of the technical scheme are as follows: the photoelectric balance analog-to-digital conversion group includes: the photoelectric balance detection unit is used for setting a photoelectric balance detector through beat frequency of the local oscillator light source and the received light signal through the optical mixer; the coherent detection amplitude-phase maintaining unit inputs the first received polarized beam-splitting coherent signal and the second received polarized beam-splitting coherent signal into the photoelectric balance detector, and the photoelectric balance detector carries out coherent detection; the amplitude and phase information carried in the signal optical domain is completely reserved in the electric signal after photoelectric conversion; processing by a front end orthogonalization and normalization module and a clock synchronization module; adopting a single-layer pure butterfly structure, forming a single-layer butterfly compensation module by 4 adaptive finite impulse corresponding FIR filters, and compensating chromatic dispersion and polarization mode chromatic dispersion; the clock synchronous analog-to-digital conversion unit obtains two orthogonal in-phase components I and orthogonal components Q of the OFDM signal after photoelectric conversion of the balanced receiver; the two paths of amplitude and phase mismatch of the in-phase component I and the quadrature component Q in two polarization directions are compensated and corrected, and the sampling clocks of the receiving and transmitting ends are completely synchronous; analog-to-digital conversion is carried out, A/D conversion is carried out by a real-time oscilloscope, and digital signals after the A/D conversion are stored for offline processing; acquiring a photoelectric balance analog-to-digital conversion signal; loss such as dispersion irrelevant to polarization can be compensated, and signal quality is greatly improved.

In one embodiment, the set of signal processing transcoding transformations comprises:

The working principle of the technical scheme is as follows: the signal processing decoding conversion group comprises:

The beneficial effects of the technical scheme are as follows: the signal processing decoding conversion group comprises: the double-layer digital signal processing unit adopts a double-layer structure digital signal processing DSP to realize the decoding output of signals according to photoelectric balance analog-to-digital conversion signals; the digital signal differential operation unit, the double-layer structure digital signal processing DSP includes: a first layer digital signal processing DSP and a second layer digital signal processing DSP; the first layer digital signal processing DSP and the second layer digital signal processing DSP respectively run at different speeds, the chromatic dispersion is approximately unchanged under millisecond level, the polarization mode chromatic dispersion is changed with time, and the tap coefficient of the filter does not need to be updated frequently in the chromatic dispersion compensation process; the loss compensation estimation output unit compensates the loss irrelevant to polarization through the first layer digital signal processing DSP; performing polarization dependent loss compensation on the second layer digital signal processing DSP; polarization dependent loss compensation includes: polarization rotation compensation and polarization mode dispersion compensation; the loss is estimated and compensated by a digital signal processing demodulation module and a digital signal processing algorithm, so that the regeneration and recovery of the original transmitting signal are completed; obtaining a 400G coherent light conversion output signal; the method brings great convenience to the realization of digital signal processing, the dispersion is approximately unchanged in millisecond magnitude, and the polarization mode dispersion is changed with time, so that tap coefficients of a filter do not need to be updated frequently in the dispersion compensation process.

In one embodiment, the digital signal processing demodulation module includes:

The working principle of the technical scheme is as follows: the digital signal processing demodulation module comprises:

the parallel-serial conversion bit calculation subunit extracts pilot frequency and realizes estimation and compensation of phase noise; converting the signal into parallel and serial and comparing the signal with the original bit to calculate the bit error rate;

The OFDM signal receiving comprises receiving in an off-line processing mode, and the obtained in-phase component I and quadrature component Q are converted into digital signals through A/D; the off-line processing mode receives and adopts a digital signal processing method to complete demodulation of OFDM signals, A/D conversion is realized by a real-time oscilloscope, and the digital signals after A/D conversion are stored for off-line processing; the processed digital signal is demodulated by the following digital signal processing steps: s1, serial-parallel conversion is carried out to obtain parallel signals; s2, symbol synchronization is used for determining the starting length of the OFDM signal; s3, estimating and compensating frequency offset of the received OFDM signals; s4, the signal is changed into a frequency domain from a time domain by fast Fourier transform; s5, extracting a training sequence for channel estimation and completing channel estimation and channel equalization; s6, extracting pilot frequency and realizing estimation and compensation of phase noise; s7, converting the signal into parallel and serial and comparing the parallel and serial signals with the original bit to calculate the bit error rate.

The beneficial effects of the technical scheme are as follows: the digital signal processing demodulation module comprises: the serial-parallel frequency offset compensation subunit converts the serial-parallel frequency offset compensation subunit into parallel signals; determining an OFDM signal start length through symbol synchronization; estimating and compensating the frequency offset of the received OFDM signal; a time-frequency transformation estimation equalization subunit, which changes the signal from the time domain to the frequency domain through fast Fourier transformation; extracting training sequences for channel estimation and completing channel estimation and channel equalization; the parallel-serial conversion bit calculation subunit extracts pilot frequency and realizes estimation and compensation of phase noise; the signal is converted in parallel and serial and the error rate is calculated in comparison with the original bit.

The working principle of the technical scheme is as follows: a preparation process of a coherent optical module comprises the following steps:

s500, respectively interfering the two groups of polarized beam splitting signals with local oscillation light to obtain two groups of local oscillation coherent signals; the local oscillation light is local oscillation light;

The beneficial effects of the technical scheme are as follows: a preparation process of a coherent optical module comprises the following steps: at a signal transmission end, respectively generating high-net-baud-rate QAM-16 signals through a dual-polarization IQ electro-optic modulation platform to obtain two groups of high-bit-rate optical signals; coupling the two groups of high bit rate optical signals to two different polarization states of the optical fiber through a first polarization rotating beam splitter/combiner PRS; according to the two different polarization states, coherent optical signal transmission of the single fiber 400G is carried out, and a high-speed coherent transmission signal of the polarized beam-splitting single fiber 400G is obtained; at a signal receiving end, splitting the polarized beam splitting single fiber 400G high-speed coherent transmission signal through a second polarized rotary beam splitting and combining device PRS to obtain two groups of polarized beam splitting signals; respectively interfering the two groups of polarized beam splitting signals with local oscillation light to obtain two groups of local oscillation coherent signals; inputting two groups of local oscillator coherent signals into a photoelectric balance detector and performing analog-to-digital conversion to obtain photoelectric balance analog-to-digital conversion signals; according to the photoelectric balance analog-digital conversion signal, decoding output of the signal is realized through a digital signal processing DSP, and a 400G coherent light conversion output signal is obtained; the module chip equalizes the high-speed signals to the transmitting end and the receiving end; the transmitting end and the receiving end balance and compensate the loss of data when transmitting in a lossy link, carry out high-speed link design and loss compensation, and obtain an open eye diagram and a BER bit error rate which accords with the specification at the receiving end; synchronously developing an intelligent automatic production debugging tool and automatic production debugging software, and intelligently and automatically carrying out configuration debugging on a large number of parameters of the optical module software; performing 400G coherent light module production and adjustment and measurement to realize preparation; the method has the advantages that great convenience is brought to the realization of digital signal processing, the dispersion is approximately unchanged in millisecond order, and the polarization mode dispersion is changed with time, so that tap coefficients of a filter do not need to be updated frequently in the dispersion compensation process; the error rate of the system can be effectively reduced, the transmission distance can be prolonged, and the aim of reducing the cost of the system can be realized with small redundancy cost; the use of FEC can effectively improve the performance of the system; the realization of the whole system relates to the coding, modulation and post-processing of high-speed photoelectric signals, the practical test and the productization test of the whole optical module system, and the photoelectric system integration of high-performance elements of a module series is realized.

Although embodiments of the present invention have been disclosed above, it is not limited to the details and embodiments shown and described, it is well suited to various fields of use for which the invention would be readily apparent to those skilled in the art, and accordingly, the invention is not limited to the specific details and illustrations shown and described herein, without departing from the general concepts defined in the claims and their equivalents.

Claims

1. A coherent optical module, comprising:

2. A coherent optical module according to claim 1, wherein said transmission-side electro-optical modulation group comprises:

3. A coherent optical module according to claim 1, wherein said polarization beam-splitting frequency-division coupling group comprises:

4. A coherent optical module according to claim 1, wherein said high-speed coherent signal transmission group comprises:

5. A coherent optical module according to claim 1, wherein said receiving-side polarization beam-splitting group comprises:

6. A coherent optical module according to claim 1, wherein said split-beam signal-to-light interference group comprises:

7. A coherent optical module according to claim 1, wherein said photoelectric balance analog-to-digital conversion group comprises:

8. The coherent optical module according to claim 1, wherein said signal processing transcoding group comprises:

9. A coherent optical module according to claim 8, wherein said digital signal processing demodulation module comprises:

10. A process for preparing a coherent optical module according to claims 1-9, comprising: