CN116260521B - Optical domain signal equalization apparatus and method thereof - Google Patents
Optical domain signal equalization apparatus and method thereof Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
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- H04B10/54—Intensity modulation
- H04B10/541—Digital intensity or amplitude modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
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- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/61—Coherent receivers
- H04B10/616—Details of the electronic signal processing in coherent optical receivers
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Abstract
The application provides an optical domain signal equalization device and a method thereof. The device comprises a light splitting delay module, a nonlinear modulation module, a light combining module, a light detection module and an electrical control module, wherein the light splitting delay module is used for dividing an input optical signal into a plurality of optical signals with delay between each other and inputting the optical signals into the nonlinear modulation module; the nonlinear modulation module comprises a first-order modulation module and a second-order modulation module, and the first-order modulation module and the second-order modulation module are respectively used for carrying out intensity modulation on a plurality of optical signals; the optical combining module is used for grouping the optical signals modulated by the first-order modulation module and the second-order modulation module; the optical detection module is used for converting the grouped optical signals into corresponding electrical signals; and the electrical control module is used for judging and calculating the error rate based on the electric signals so as to adjust the intensity modulation coefficients of the first-order modulation module and the second-order modulation module in the equalization algorithm. The method and the device can compensate linear damage of the optical signal and nonlinear damage.
Description
Technical Field
The present disclosure relates to the field of optical communications technologies, and in particular, to an optical domain signal equalization apparatus and a method thereof.
Background
In recent years, new applications such as internet of things, augmented virtual reality, cloud computing, cloud storage, and other software services have driven the growth of global IP data traffic, and thus, the application demands of higher speed and lower latency are put forward in the field of optical communications.
For the high-speed low-delay optical communication system, if the traditional digital signal processing technology is adopted to compensate signal damage, higher delay is brought, and the current real-time application requirement cannot be met. In view of this problem, optical domain equalization techniques have been developed, but the optical domain equalization techniques proposed by current researchers only can compensate for linear impairments of signals, and still need to be combined with digital signal processing to compensate for nonlinear impairments of signals, and cannot fundamentally solve the delay problem caused by digital signal processing.
Disclosure of Invention
The invention aims to provide optical domain signal equalization equipment and a method thereof, which can compensate linear damage of an optical signal and nonlinear damage.
One aspect of the present application provides an optical domain signal equalization device. The optical domain signal equalization equipment comprises a light splitting delay module, a nonlinear modulation module, a light beam combining module, an optical detection module and an electrical control module, wherein the light splitting delay module is used for dividing an input optical signal into a plurality of optical signals with delay between each other and inputting the optical signals into the nonlinear modulation module; the nonlinear modulation module comprises a first-order modulation module and a second-order modulation module, and the first-order modulation module and the second-order modulation module are respectively used for carrying out intensity modulation on a plurality of optical signals; the light beam combining module is used for grouping the light signals modulated by the first-order modulation module and the second-order modulation module; the optical detection module is used for converting the grouped optical signals into corresponding electrical signals; and the electrical control module is used for judging and calculating the error rate based on the electrical signals so as to adjust the intensity modulation coefficients of the first-order modulation module and the second-order modulation module in an equalization algorithm.
Further, the light beam combining module comprises a first light beam combiner and a second light beam combiner, wherein in the equalization algorithm, light signals with positive intensity modulation coefficients are divided into a group to be input into the first light beam combiner, and the first light beam combiner combines the light signals into a path of light signals with positive intensity modulation coefficients; in the equalization algorithm, optical signals with negative intensity modulation coefficients are divided into a group to be input into the second beam combiner, and the second beam combiner combines the optical signals into one path of optical signals with negative intensity modulation coefficients.
Further, the light detection module comprises a first photoelectric detector and a second photoelectric detector, wherein the first photoelectric detector is used for detecting a positive modulation coefficient light signal input by the first light combiner so as to generate a first photocurrent; the second photoelectric detector is used for detecting a negative modulation coefficient optical signal input by the second optical combiner to generate a second photocurrent, and the electrical control module is used for judging and calculating an error rate based on a difference value of the first photocurrent and the second photocurrent.
Further, the anode of the first photodetector is connected with the cathode of the second photodetector, the cathode of the first photodetector is connected to a first voltage source, the anode of the second photodetector is connected to a second voltage source, and the voltage of the first voltage source is higher than that of the second voltage source, wherein the electrical control module is connected between the anode of the first photodetector and the cathode of the second photodetector and is used for receiving a difference electrical signal obtained by subtracting the first photocurrent from the second photocurrent.
Further, the electrical control module comprises an analog-to-digital converter, a digital-to-analog converter and a central control chip, wherein the analog-to-digital converter is used for converting the difference electric signal into a digital signal; the central control chip is used for judging and calculating the error rate based on the digital signals to obtain the weight coefficients of the first-order modulation module and the second-order modulation module, and transmitting the digital signals containing the weight coefficients to the digital-to-analog converter; the digital-to-analog converter is used for converting the digital signals of the weight coefficients into analog signals and respectively transmitting the analog signals to the first-order modulation module and the second-order modulation module in the nonlinear modulation module to serve as intensity modulation coefficients of the first-order modulation module and the second-order modulation module in the equalization algorithm.
Further, the optical splitting delay module comprises a first optical beam splitter and an optical delay device, wherein the first optical beam splitter is used for splitting the input optical signal into M sub-signals with equal power; the optical retarder is used for delaying the M sub-signals from each other.
Further, the optical delay device comprises M-1 optical delay devices, wherein the M-1 optical delay devices respectively generate different signal delays for corresponding M-1 sub-signals.
Further, the M sub-signals create equal delays with respect to each other and the delays are equal to the symbol period of the input optical signal or a multiple of the symbol period of the input optical signal.
Further, the first-order modulation module includes M second optical splitters and M first optical modulators, the M second optical splitters are respectively configured to correspondingly receive the M sub-signals having delays therebetween, each of the second optical splitters is configured to subdivide a corresponding one of the sub-signals into m+2 parts, so as to obtain m× (m+2) sub-signals in total, the M first optical modulators are respectively configured to correspondingly receive one of the m+2 parts of the M sub-signals and perform intensity modulation thereon, and an intensity modulation coefficient of the first-order modulation module includes a first-order weight coefficient of M first optical modulator taps; wherein the remaining m× (m+1) parts of the unmodulated sub-signal are input into the second order modulation module.
Further, the second-order modulation module includes m× (m+1)/2 optical mixers and m× (m+1)/2 second optical modulators, where m× (m+1)/2 optical mixers are respectively configured to mix m× (m+1) sub-signals input by the second optical splitter, generate m× (m+1)/2 mixed sub-signals, and input the m× (m+1)/2 sub-signals to the m× (m+1)/2 second optical modulators, respectively; and the M× (M+1)/2 second optical modulators are respectively used for carrying out corresponding intensity modulation on the M× (M+1)/2 mixed sub-signals, and the intensity modulation coefficients of the second-order modulation module comprise second-order weight coefficients of the M× (M+1)/2 second optical modulator taps.
Another aspect of the present application provides a method of optical domain signal equalization. The optical domain signal equalization method comprises the following steps: dividing an input optical signal into a plurality of optical signals with delay therebetween by a beam-splitting delay module; the intensity modulation is carried out on a plurality of optical signals through a first-order modulation module and a second-order modulation module in the nonlinear modulation module respectively; grouping the optical signals modulated by the first-order modulation module and the second-order modulation module through an optical beam combining module; converting the grouped optical signals into corresponding electric signals through the optical detection module; and based on the electric signals, judging and calculating the error rate by an electric control module to adjust the intensity modulation coefficients of the first-order modulation module and the second-order modulation module in an equalization algorithm.
Further, the optical delay module includes a first optical beam splitter and M-1 optical delays, and the splitting the input optical signal into a plurality of optical signals having delays therebetween by the optical delay module includes: dividing the input optical signal into M sub-signals with equal power by the first optical beam splitter; and generating different signal delays for the corresponding M-1 part sub-signals through the M-1 optical delays respectively so that the M part sub-signals have delays among each other.
Further, the M sub-signals create equal delays with respect to each other and the delays are equal to the symbol period of the input optical signal or a multiple of the symbol period of the input optical signal.
Further, the first-order modulation module includes M second optical splitters and M first optical modulators, and the performing, by using a first-order modulation module and a second-order modulation module in the nonlinear modulation module, intensity modulation on the plurality of optical signals respectively includes: inputting one of the M+2 parts of the M parts of sub-signals into M first optical modulators correspondingly, and respectively carrying out intensity modulation on the M first optical modulators, wherein the intensity modulation coefficients of the first-order modulation module comprise first-order weight coefficients of M first optical modulator taps; and inputting the remaining M× (M+1) parts of the sub-signals which are not modulated into the second-order modulation modules, and respectively carrying out intensity modulation on the sub-signals by the second-order modulation modules.
Further, the second-order modulation module includes m× (m+1)/2 optical mixers and m× (m+1)/2 second optical modulators, and the modulating the intensity of the plurality of optical signals by the first-order modulation module and the second-order modulation module in the nonlinear modulation module respectively further includes: dividing each part of the M sub-signals into M+2 parts correspondingly through M second optical beam splitters; mixing M (M+1) sub-signals input by the second optical beam splitter by M (M+1)/2 optical mixers in pairs to generate M (M+1)/2 mixed sub-signals, and inputting the M (M+1)/2 mixed sub-signals to the M (M+1)/2 second optical modulators; and (2) performing corresponding intensity modulation on the M× (M+1)/2 mixed sub-signals by the M× (M+1)/2 second optical modulators respectively, wherein the intensity modulation coefficients of the second-order modulation module comprise second-order weight coefficients of the M× (M+1)/2 second optical modulator taps.
Further, the optical beam combining module includes a first optical beam combiner and a second optical beam combiner, and the grouping the optical signals modulated by the first-order modulation module and the second-order modulation module by the optical beam combining module includes: dividing the optical signals with positive intensity modulation coefficients in the equalization algorithm into a group, inputting the group into the first beam combiner, and combining the group into one path of positive modulation coefficient optical signals by the first beam combiner; dividing the optical signals with the negative intensity modulation coefficients in the equalization algorithm into a group, inputting the group of optical signals into the second beam combiner, and combining the optical signals into one path of optical signals with the negative intensity modulation coefficients by the second beam combiner.
Further, the optical detection module includes a first photodetector and a second photodetector, and the converting, by the optical detection module, the grouped optical signals into corresponding electrical signals includes: detecting, by the first photodetector, a positive modulation factor optical signal input by the first optical combiner to generate a first photocurrent; and detecting a negative modulation factor optical signal input by the second optical combiner by the second photodetector to generate a second optical current, wherein decision and error rate calculation are performed based on a difference value obtained by subtracting the first optical current and the second optical current.
Further, the determining and calculating the bit error rate by the electrical control module based on the electrical signal to adjust the intensity modulation coefficients of the first-order modulation module and the second-order modulation module in the equalization algorithm includes: converting the difference electric signal obtained by subtracting the first photocurrent from the second photocurrent into a digital signal; performing decision and bit error rate calculation based on the digital signal to obtain weight coefficients of the first-order modulation module and the second-order modulation module; and converting the digital signals containing the weight coefficients into analog signals, and respectively transmitting the analog signals to the first-order modulation module and the second-order modulation module in the nonlinear modulation module to serve as intensity modulation coefficients of the first-order modulation module and the second-order modulation module in the equalization algorithm.
The optical domain signal equalization equipment and the method thereof have the following beneficial technical effects:
(1) The method and the device can directly compensate linear damage and nonlinear damage in the optical communication system in the optical domain, do not need an additional digital signal processing module, omit the digital signal processing process of a receiving end, greatly reduce the signal processing time delay and can meet the current more and more real-time application demands.
(2) The equalization weight can be updated by the electrical control module, so that the optical communication system with different requirements can be met, the flexibility is extremely high, and the application method can be adapted to various application scenes.
Drawings
Fig. 1 is a schematic diagram of an overall structure of an optical domain signal equalization apparatus according to an embodiment of the present application.
Fig. 2 is a schematic structural diagram of a spectral delay module in an optical domain signal equalization apparatus according to an embodiment of the present application.
Fig. 3 is a schematic structural diagram of a nonlinear modulation module in an optical domain signal equalization apparatus according to an embodiment of the present application.
Fig. 4 is a schematic structural diagram of a photosynthetic beam module in an optical domain signal equalization apparatus according to an embodiment of the present application.
Fig. 5 is a schematic structural diagram of an optical detection module in an optical domain signal equalization apparatus according to an embodiment of the present application.
Fig. 6 is a schematic structural diagram of an electrical control module in an optical domain signal equalization apparatus according to an embodiment of the present application.
Fig. 7 is a flowchart of an optical domain signal equalization method according to an embodiment of the present application.
Detailed Description
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus consistent with some aspects of the present application as detailed in the accompanying claims.
The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless defined otherwise, technical or scientific terms used in the embodiments of the present application should be given the ordinary meaning as understood by one of ordinary skill in the art to which the present application belongs. As used in the specification of this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.
The application provides an optical domain signal equalization device. Fig. 1 discloses an overall structure schematic diagram of an optical domain signal equalization device 100 according to an embodiment of the present application. As shown in fig. 1, the optical domain signal equalizing apparatus 100 according to one embodiment of the present application includes an optical splitting delay module 110, a nonlinear modulation module 120, an optical combining module 130, an optical detection module 140, and an electrical control module 150. The optical splitting delay module 110 may be configured to receive an input optical signal, split the input optical signal into a plurality of optical signals having delays therebetween, and input the optical signals to the nonlinear modulation module 120. The nonlinear modulation module 120 includes a first-order modulation module and a second-order modulation module, which can be used to perform intensity modulation on a plurality of optical signals. The optical combining module 130 may group the optical signals modulated by the first-order modulation module and the second-order modulation module. The optical detection module 140 may convert the packetized optical signals into corresponding electrical signals. The electrical control module 150 may make decisions and bit error rate calculations based on the electrical signals to adjust the intensity modulation coefficients of the first and second order modulation modules in the equalization algorithm.
The structure of these five blocks in the optical domain signal equalizing apparatus 100 will be described in detail in order with reference to the accompanying drawings.
Fig. 2 discloses a schematic structural diagram of the optical splitting delay module 110 in the optical domain signal equalization device 100 according to one embodiment of the present application. As shown in fig. 2, the optical delay module 110 may include a first optical beam splitter 111 and an optical delay 112. The first optical splitter 111 may split the input optical signal into M sub-signals of equal power, i.e. x (k), x (k-1), x (k-2), … …, x (k-m+1). The M sub-signals then pass through an optical delay 112, and the M sub-signals are delayed from each other by the optical delay 112.
In the embodiment shown in fig. 2, the optical delay module 110 includes M-1 optical delays 112, and the M-1 optical delays 112 can respectively generate different signal delays for the corresponding M-1 sub-signals. Wherein the first optical signal does not pass through the optical retarder 112, i.e. the retardation t of the sub-signal x (k) is considered 0 =0; the second optical signal is passed through an optical delay 112 (e.g., delay line 1) to produce a delay T 1 I.e. consider the delay t of the sub-signal x (k-1) 1 =T 1 The method comprises the steps of carrying out a first treatment on the surface of the The third optical signal is passed through an optical delay 112 (e.g., delay line 2) to produce a delay T 2 I.e. consider the delay t of the sub-signal x (k-2) 2 =T 2 The method comprises the steps of carrying out a first treatment on the surface of the By analogy, the mth optical signal is passed through an optical delay 112 (e.g., delay line M-1) to produce a delay T M-1 I.e. consider the delay t of x (k-M+1) m-1 =T M-1 . Finally, the M optical signals having a certain delay from each other are input into the nonlinear modulation module 120.
In one embodiment, the M sub-signals create an equal delay with respect to each other and the delay is equal to the symbol period of the input optical signal, i.e. Δt=t 1 -t 0 =t 2 -t 1 =…=t m-1 -t m-2 T, T is the symbol period of the input optical signal. In another embodiment, the M sub-signals have equal time delays, and the time delays are equal to multiples of the symbol period T of the input optical signal, and can be specifically adjusted according to the processing precision requirement of the optical communication system for the signals. Of course, the present application is not limited thereto. In other embodiments, M partsThe signals may also be delayed at unequal intervals from one another, which may be adjusted according to the particular situation of the optical communication system in which they are located, without limitation.
Fig. 3 discloses a schematic structural diagram of the nonlinear modulation module 120 in the optical domain signal equalization apparatus 100 according to one embodiment of the present application. As shown in fig. 3, the first order modulation module in the nonlinear modulation module 120 includes M second optical beam splitters 121 and M first optical modulators 122. The M-ary sub-signals input to the nonlinear modulation module 120 by the optical delay module 110 are first correspondingly received by the M second optical splitters 121, respectively, where each of the second optical splitters 121 can subdivide a corresponding one of the sub-signals into m+2 parts, so that m× (m+2) sub-signals can be obtained in total. One of the m+2 parts of the M part sub-signal is then correspondingly fed to the M first optical modulators 122, and the M first optical modulators 122 may respectively correspondingly receive and intensity modulate one of the m+2 parts of the M part sub-signal. Wherein the intensity modulation coefficients of the first-order modulation module include M first-order weight coefficients of the taps of the first optical modulator 122, i.eThereby, M sub-signals after first order modulation can be generated, namely。
The remaining m× (m+1) parts of the unmodulated sub-signal are then input to a second order modulation module. With continued reference to fig. 3, in some embodiments, the second order modulation module may include m× (m+1)/2 optical mixers 123 and m× (m+1)/2 second optical modulators 124. First, m× (m+1)/2 optical mixers 123 mix the total m× (m+1) sub-signals inputted from the second optical splitter 121 in the first-order modulation module two by two to generate m× (m+1)/2 mixed sub-signalsThe method comprises the steps of carrying out a first treatment on the surface of the Then, M× (M+1)/2 mixed sub-signals are respectively and correspondingly input into a second-order modulation moduleM+1)/2 second optical modulators 124, and m× (m+1)/2 mixed sub-signals are respectively subjected to corresponding intensity modulation by m× (m+1)/2 second optical modulators 124. Wherein the intensity modulation coefficients of the second order modulation module include M x (M+1)/2 second order weight coefficients of the taps of the second optical modulator 124, for a total of M x (M+1)/2 second order weight coefficients, i.eThus M× (M+1)/2 mixed and modulated sub-signals can be generated, i.e。
Finally, the M first-order modulated sub-signals and the m× (m+1)/2 second-order modulated sub-signals are transmitted together to the optical combining module 130.
Preferably, the first light modulator 122 and the second light modulator 124 may use an electroabsorption modulator insensitive to the polarization state of light for intensity modulation, but other light modulators such as electro-optical light, acousto-optic light and the like are not limited to be selected due to the factors of cost, control difficulty and the like.
Fig. 4 discloses a schematic structural diagram of the optical beam combining module 130 in the optical domain signal equalizing apparatus 100 according to one embodiment of the present application. As shown in fig. 4, the light combining module 130 includes a first light combiner 131 and a second light combiner 132. The above-mentioned M first-order modulated sub-signals and m× (m+1)/2 second-order modulated sub-signals inputted to the optical combiner 130 by the nonlinear modulator 120 are divided into two groups, wherein the sub-signals with positive intensity modulation coefficients are divided into one group in the equalization algorithm and inputted to the first optical combiner 131, and the first optical combiner 131 combines the sub-signals into one optical signal, which is referred to herein as a positive modulation coefficient optical signal. In addition, in the equalization algorithm, the optical signals with negative intensity modulation coefficients are divided into a group and input to the second optical combiner 132, and the second optical combiner 132 combines the optical signals into one optical signal, which is referred to herein as a negative modulation coefficient optical signal.
The equalization algorithm described in the present application is a signal impairment compensation algorithm customized for the optical communication system, which is not limited in the present application, i.e. which sub-signals have positive intensity modulation coefficients and which sub-signals have negative intensity modulation coefficients may be switched according to the change of the actual application scenario, and the connection manner shown in fig. 4 is only used as an illustration and not used as a limitation of the present application.
Therefore, through the optical combining module 130, the optical combining module 130 is responsible for combining the total of M first-order modulated sub-signals input by the first-order modulation module and the total of m× (m+1)/2 second-order modulated sub-signals input by the second-order modulation module into two optical signals according to the equalization requirement, i.e. a positive modulation coefficient optical signal and a negative modulation coefficient optical signal, and inputting the two optical signals to the optical detection module 140 respectively.
Fig. 5 discloses a schematic structural diagram of the optical detection module 140 in the optical domain signal equalizing apparatus 100 according to one embodiment of the present application. As shown in fig. 5, the light detection module 140 includes a first photodetector PD1 and a second photodetector PD2. The above-described positive modulation factor optical signal and negative modulation optical signal input to the optical detection module 140 by the optical beam combining module 130 are detected by the two photodetectors, respectively. Wherein the first photodetector PD1 may detect the positive modulation factor optical signal input by the first optical combiner 131 to generate a first photocurrent I1; the second photodetector PD2 may detect the negative modulation factor optical signal input by the second optical combiner 132 to generate a second photocurrent I2.
The electrical control module 150 may perform decision and bit error rate calculation based on the subtracted difference between the first photocurrent I1 and the second photocurrent I2.
In some embodiments, the anode of the first photodetector PD1 is connected to the cathode of the second photodetector PD2, and the cathode of the first photodetector PD1 is connected to the first voltage source V PD1 The anode of the second photodetector PD2 is connected to a second voltage source V PD2 A first voltage source V PD1 Is higher than the second voltage source V PD2 I.e. the cathode of the first photo detector PD1 is connected to a high voltage signal source and the anode of the second photo detector PD2 is connected to a low voltage source. The photocurrent thus obtained flows to the node in the direction shown in fig. 5P is opposite in direction, i.e. Δi=i1-I2. The electrical control module 150 is connected between the anode of the first photo detector PD1 and the cathode of the second photo detector PD2, and can be used to receive the difference electric signal Δi obtained by subtracting the first photo current and the second photo current inputted by the photo detection module.
The first and second photodetectors PD1 and PD2 may include, for example, but not limited to, photodiodes, avalanche photodiodes, phototriodes, and the like, as long as conversion of optical signals into electrical signals can be achieved, which is not limited in this application.
Fig. 6 discloses a schematic structural diagram of the electrical control module 150 in the optical domain signal equalization apparatus 100 according to one embodiment of the present application. As shown in fig. 6, the electrical control module 150 includes an Analog-to-Digital Converter (ADC) 151, a Digital-to-Analog Converter (DAC) 153, and a central control chip 152. First, the difference electric signal Δi is converted into a digital signal by the analog-to-digital converter 151. Then, the central control chip 152 performs decision and bit error rate calculation based on the digital signal, so as to obtain the weight coefficients of the first-order modulation module and the second-order modulation module, and sends the digital signal containing the weight coefficients to the digital-to-analog converter 153. The digital signals of the weight coefficients are converted into analog signals by the digital-to-analog converter 153 and are respectively transmitted to the first-order modulation module and the second-order modulation module in the nonlinear modulation module 120, so that the digital-to-analog converter can be used as the intensity modulation coefficients of the first-order modulation module and the second-order modulation module in the equalization algorithm, namely the first-order weight coefficientsAnd second order weight coefficient. Thus, the equalized optical signal can be recovered.
Preferably, the central control chip 152 in the electrical control module 150 may include, for example, but not limited to, a programmable logic array (Field Programmable Gate Array, FPGA), a microcontroller (Mirco Controller Unit, MCU), and the like, where the specification of the chip depends on the processing requirements of the optical communication system on the signals.
Preferably, the digital-to-analog converter 153 in the electrical control module 150 may use a high-precision digital-to-analog converter with more than 12 bits for reporting the photocurrent generated by the detection signal, so as to ensure that the signal has higher processing precision. In addition, the number of digital-to-analog converters 153 shown in fig. 6 is merely shown for convenience of illustration and is not intended to limit the present application, and in fact, the number of digital-to-analog converters 153 in the electrical control module 150 of the present application may include one or more, as long as the number of channels that the digital-to-analog converters 153 generally have is not less than the number of first-order weight coefficients and second-order weight coefficients added.
The optical domain signal equalization device 100 of the present application has at least the following beneficial technical effects:
(1) The optical domain signal equalization device 100 can directly compensate linear damage and nonlinear damage in an optical domain optical communication system, does not need an additional digital signal processing module, omits a digital signal processing process of a receiving end, greatly reduces signal processing time delay, and can meet more and more current real-time application requirements.
(2) The optical domain signal equalization device 100 can update equalization weights by the electrical control module 150, can meet optical communication systems with different requirements, has extremely high flexibility, and can adapt to various application scenes.
The application also provides an optical domain signal equalization method. Fig. 7 discloses a flowchart of an optical domain signal equalization method according to an embodiment of the present application. As shown in fig. 7, the optical domain signal equalization method according to one embodiment of the present application may include steps S1 to S5.
In step S1, the input optical signal may be divided into a plurality of optical signals having a delay with respect to each other by the optical splitting delay module 110.
In step S2, the intensity modulation may be performed on the several optical signals by a first-order modulation module and a second-order modulation module in the nonlinear modulation module 120, respectively.
In step S3, the optical signals modulated by the first-order modulation module and the second-order modulation module may be grouped by the optical combining module 130.
In step S4, the grouped optical signals may be converted into corresponding electrical signals by the optical detection module 140.
In step S5, decision and bit error rate calculation are performed by the electrical control module 150 based on the electrical signal to adjust the intensity modulation coefficients of the first-order modulation module and the second-order modulation module in the equalization algorithm.
In some embodiments, the optical delay module 110 may include a first optical splitter 111 and M-1 optical delays 112. Step S1 may include step S11 and step S12. In step S11, the input optical signal is split into M sub-signals of equal power by the first optical splitter 111. In step S12, the M-1 sub-signals are respectively delayed by the M-1 optical delays 112 to have different signal delays.
Optionally, the M sub-signals generate equal time delays therebetween, and the time delays are equal to the symbol period T of the input optical signal or multiple of the symbol period T of the input optical signal, which can be specifically adjusted according to the processing precision requirement of the optical communication system on the signals.
In some embodiments, a first order modulation module of the nonlinear modulation module 120 may include M second optical beam splitters 121 and M first optical modulators 122. Step S2 may include step S21 and step S22. In step S21, one of the m+2 parts of the M parts of sub-signals is input to the M first optical modulators 122, and is intensity modulated by the M first optical modulators 122, respectively, wherein the intensity modulation coefficients of the first-order modulation module include first-order weight coefficients of taps of the M first optical modulators 122. In step S22, the remaining m× (m+1) parts of the unmodulated sub-signals are input to the second-order modulation modules, which are intensity-modulated by the second-order modulation modules, respectively.
In some embodiments, the second order modulation module in the nonlinear modulation module 120 may include m× (m+1)/2 optical mixers 123 and m× (m+1)/2 second optical modulators 124. Step S2 further includes steps S23 to S25. In step S23, each of the M parts of the sub-signals is subdivided into m+2 parts by the M second optical beam splitters, respectively. In step S24, the m× (m+1) sub-signals inputted from the second optical splitter 121 are mixed in pairs by the m× (m+1)/2 optical mixers 123, respectively, to generate m× (m+1)/2 mixed sub-signals, which are inputted to the m× (m+1)/2 second optical modulators 124, respectively. In step S25, the m× (m+1)/2 second optical modulators 124 respectively perform corresponding intensity modulation on the m× (m+1)/2 mixed sub-signals, and the intensity modulation coefficients of the second-order modulation module include the second-order weight coefficients of the m× (m+1)/2 second optical modulators 124 taps.
In some embodiments, the light combining module 130 may include a first light combiner 131 and a second light combiner 132. Step S3 may include step S31 and step S32. In step S31, the optical signals with positive intensity modulation coefficients in the equalization algorithm are divided into a group, and input to the first beam combiner 131, and the first beam combiner 131 combines the optical signals into one path of optical signals with positive modulation coefficients. In step S32, the optical signals with negative intensity modulation coefficients in the equalization algorithm are divided into a group and input to the second beam combiner 132, and the second beam combiner 132 combines the optical signals into one path of optical signals with negative intensity modulation coefficients.
In some embodiments, the light detection module 140 may include a first photodetector PD1 and a second photodetector PD2. Step S4 may include step S41 and step S42. In step S41, the positive modulation factor optical signal input by the first beam combiner 131 is detected by the first photodetector PD1 to generate a first photocurrent. In step S42, the negative modulation factor optical signal input by the second beam combiner 132 is detected by the second photodetector PD2 to generate a second photocurrent. In step S5, the decision and the bit error rate calculation may be performed based on the difference obtained by subtracting the first photocurrent generated in step S41 and the second photocurrent generated in step S42.
In some embodiments, step S5 may include steps S51 to S53. In step S51, the difference electric signal obtained by subtracting the first and second photocurrents is converted into a digital signal. In step S52, decision and bit error rate calculation are performed based on the digital signal to obtain the weight coefficients of the first-order modulation module and the second-order modulation module. In step S53, the digital signal containing the weight coefficient is converted into an analog signal, and is respectively transmitted to the first-order modulation module and the second-order modulation module in the nonlinear modulation module 120, so as to be used as the intensity modulation coefficients of the first-order modulation module and the second-order modulation module in the equalization algorithm.
The optical domain signal equalization method can compensate both linear damage and nonlinear damage of the optical signal, so that the digital signal processing process of a receiving end is thoroughly omitted, the signal processing time delay is greatly reduced, and more current real-time application requirements can be met.
The optical domain signal equalization method can meet optical communication systems with different requirements, has extremely high flexibility, and can be suitable for various application scenes.
The optical domain signal equalization device and the method thereof provided by the embodiment of the application are described in detail above. Specific examples are used herein to describe the optical domain signal equalization apparatus and method according to the embodiments of the present application, where the description of the above embodiments is only for helping to understand the core ideas of the present application, and is not intended to limit the present application. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made herein without departing from the spirit and principles of the invention, which should also fall within the scope of the appended claims.
Claims (12)
1. An optical domain signal equalization device, characterized by: comprises a light splitting delay module, a nonlinear modulation module, a light combining module, a light detection module and an electrical control module, wherein,
the optical splitting delay module is used for splitting an input optical signal into a plurality of optical signals with delay between the optical signals and inputting the optical signals into the nonlinear modulation module;
the nonlinear modulation module comprises a first-order modulation module and a second-order modulation module, and the first-order modulation module and the second-order modulation module are respectively used for carrying out intensity modulation on a plurality of optical signals;
the light beam combining module is used for grouping the light signals modulated by the first-order modulation module and the second-order modulation module;
the optical detection module is used for converting the grouped optical signals into corresponding electrical signals; a kind of electronic device with high-pressure air-conditioning system
The electrical control module is used for judging and calculating the error rate based on the electrical signals so as to adjust the intensity modulation coefficients of the first-order modulation module and the second-order modulation module in an equalization algorithm,
the optical splitting delay module comprises a first optical beam splitter and an optical delay device, wherein the first optical beam splitter is used for dividing the input optical signal into M sub-signals with equal power; the optical retarder is for delaying the M sub-signals relative to each other,
the first-order modulation module comprises M second optical splitters and M first optical modulators, wherein the M second optical splitters are respectively used for correspondingly receiving M sub-signals with delay between each other, each second optical splitter is used for dividing a corresponding sub-signal into M+2 parts so as to obtain M x (M+2) sub-signals in total, the M first optical modulators are respectively used for correspondingly receiving one of the M+2 parts of the M sub-signals and carrying out intensity modulation on the one of the M sub-signals, and the intensity modulation coefficients of the first-order modulation module comprise first-order weight coefficients of M first optical modulator taps; wherein the remaining M x (M+1) parts of the unmodulated sub-signal are input into the second order modulation module,
the second-order modulation module comprises M (M+1)/2 optical mixers and M (M+1)/2 second optical modulators, wherein the M (M+1)/2 optical mixers are respectively used for carrying out pairwise mixing on M (M+1) sub-signals input by the second optical beam splitter, generating M (M+1)/2 mixed sub-signals and respectively inputting the M (M+1)/2 sub-signals to the M (M+1)/2 second optical modulators; and the M× (M+1)/2 second optical modulators are respectively used for carrying out corresponding intensity modulation on the M× (M+1)/2 mixed sub-signals, and the intensity modulation coefficients of the second-order modulation module comprise second-order weight coefficients of the M× (M+1)/2 second optical modulator taps.
2. The optical domain signal equalizing apparatus of claim 1, wherein: the light beam combining module comprises a first light beam combiner and a second light beam combiner,
in the equalization algorithm, optical signals with positive intensity modulation coefficients are divided into a group to be input into the first beam combiner, and the first beam combiner combines the optical signals into one path of optical signals with positive modulation coefficients;
in the equalization algorithm, optical signals with negative intensity modulation coefficients are divided into a group to be input into the second beam combiner, and the second beam combiner combines the optical signals into one path of optical signals with negative intensity modulation coefficients.
3. The optical domain signal equalizing apparatus according to claim 2, wherein: the light detection module comprises a first photoelectric detector and a second photoelectric detector,
the first photoelectric detector is used for detecting a positive modulation coefficient optical signal input by the first optical combiner so as to generate a first photocurrent;
the second photodetector is configured to detect a negative modulation factor optical signal input by the second optical combiner to generate a second photocurrent,
the electrical control module is used for judging and calculating the error rate based on the difference value of the first photocurrent and the second photocurrent.
4. The optical domain signal equalization device of claim 3, wherein: the anode of the first photoelectric detector is connected with the cathode of the second photoelectric detector, the cathode of the first photoelectric detector is connected with a first voltage source, the anode of the second photoelectric detector is connected with a second voltage source, the voltage of the first voltage source is higher than that of the second voltage source,
the electrical control module is connected between the anode of the first photoelectric detector and the cathode of the second photoelectric detector and is used for receiving a difference electric signal obtained by subtracting the first photoelectric current from the second photoelectric current.
5. The optical domain signal equalizing apparatus according to claim 4, wherein: the electric control module comprises an analog-to-digital converter, a digital-to-analog converter and a central control chip,
the analog-to-digital converter is used for converting the difference electric signal into a digital signal;
the central control chip is used for judging and calculating the error rate based on the digital signals to obtain the weight coefficients of the first-order modulation module and the second-order modulation module, and transmitting the digital signals containing the weight coefficients to the digital-to-analog converter;
the digital-to-analog converter is used for converting the digital signals of the weight coefficients into analog signals and respectively transmitting the analog signals to the first-order modulation module and the second-order modulation module in the nonlinear modulation module to serve as intensity modulation coefficients of the first-order modulation module and the second-order modulation module in the equalization algorithm.
6. The optical domain signal equalizing apparatus of claim 1, wherein: the light splitting delay module comprises M-1 optical delays, wherein the M-1 optical delays respectively generate different signal delays for corresponding M-1 sub-signals.
7. The optical domain signal equalizing apparatus of claim 1, wherein: the M sub-signals create equal delays with respect to each other and the delays are equal to the symbol period of the input optical signal or an integer multiple of the symbol period of the input optical signal.
8. An optical domain signal equalization method is characterized in that: comprising the following steps:
dividing an input optical signal into a plurality of optical signals with delay therebetween by a beam-splitting delay module;
the intensity modulation is carried out on a plurality of optical signals through a first-order modulation module and a second-order modulation module in the nonlinear modulation module respectively;
grouping the optical signals modulated by the first-order modulation module and the second-order modulation module through an optical beam combining module;
converting the grouped optical signals into corresponding electric signals through an optical detection module; a kind of electronic device with high-pressure air-conditioning system
Based on the electric signal, the electric control module makes decision and error rate calculation to adjust the intensity modulation coefficients of the first-order modulation module and the second-order modulation module in an equalization algorithm,
the optical delay module comprises a first optical beam splitter and M-1 optical delays, and the optical delay module divides an input optical signal into a plurality of optical signals with delays, wherein the optical signals have the delays between the optical signals, and the optical delay module comprises: dividing the input optical signal into M sub-signals with equal power by the first optical beam splitter; generating different signal delays for the corresponding M-1 part sub-signals through the M-1 optical delays respectively so that the M part sub-signals have delays;
the first-order modulation module comprises M second optical beam splitters and M first optical modulators, and the intensity modulation of the optical signals by the first-order modulation module and the second-order modulation module in the nonlinear modulation module comprises the following steps: dividing each part of the M sub-signals into M+2 parts correspondingly through M second optical beam splitters; inputting one of the M+2 parts of the M parts of sub-signals into M first optical modulators correspondingly, and respectively carrying out intensity modulation on the M first optical modulators, wherein the intensity modulation coefficients of the first-order modulation module comprise first-order weight coefficients of M first optical modulator taps; inputting the remaining M× (M+1) parts of sub-signals which are not modulated into the second-order modulation modules, and respectively carrying out intensity modulation on the sub-signals by the second-order modulation modules;
the second-order modulation module comprises M× (M+1)/2 optical mixers and M× (M+1)/2 second optical modulators, and the intensity modulation of the optical signals by the first-order modulation module and the second-order modulation module in the nonlinear modulation module respectively further comprises: mixing M (M+1) sub-signals input by the second optical beam splitter by M (M+1)/2 optical mixers in pairs to generate M (M+1)/2 mixed sub-signals, and inputting the M (M+1)/2 mixed sub-signals to the M (M+1)/2 second optical modulators; and (2) performing corresponding intensity modulation on the M× (M+1)/2 mixed sub-signals by the M× (M+1)/2 second optical modulators respectively, wherein the intensity modulation coefficients of the second-order modulation module comprise second-order weight coefficients of the M× (M+1)/2 second optical modulator taps.
9. The optical domain signal equalization method of claim 8, wherein: the M sub-signals create equal delays with respect to each other and the delays are equal to the symbol period of the input optical signal or an integer multiple of the symbol period of the input optical signal.
10. The optical domain signal equalization method of claim 8, wherein: the optical beam combining module comprises a first optical beam combiner and a second optical beam combiner, and the grouping of the optical signals modulated by the first-order modulation module and the second-order modulation module through the optical beam combining module comprises the following steps:
dividing the optical signals with positive intensity modulation coefficients in the equalization algorithm into a group, inputting the group into the first beam combiner, and combining the group into one path of positive modulation coefficient optical signals by the first beam combiner;
dividing the optical signals with the negative intensity modulation coefficients in the equalization algorithm into a group, inputting the group of optical signals into the second beam combiner, and combining the optical signals into one path of optical signals with the negative intensity modulation coefficients by the second beam combiner.
11. The optical domain signal equalization method of claim 10, wherein: the optical detection module comprises a first photoelectric detector and a second photoelectric detector, and the converting the grouped optical signals into corresponding electrical signals by the optical detection module comprises the following steps:
detecting, by the first photodetector, a positive modulation factor optical signal input by the first optical combiner to generate a first photocurrent; a kind of electronic device with high-pressure air-conditioning system
Detecting a negative modulation factor optical signal input by the second optical combiner by the second photodetector to generate a second photocurrent,
and performing decision and bit error rate calculation based on the difference value obtained by subtracting the first photocurrent from the second photocurrent.
12. The optical domain signal equalization method of claim 11, wherein: the determining, by an electrical control module, based on the electrical signal to perform bit error rate calculation to adjust intensity modulation coefficients of the first-order modulation module and the second-order modulation module in an equalization algorithm includes:
converting the difference electric signal obtained by subtracting the first photocurrent from the second photocurrent into a digital signal;
performing decision and bit error rate calculation based on the digital signal to obtain weight coefficients of the first-order modulation module and the second-order modulation module;
and converting the digital signals containing the weight coefficients into analog signals, and respectively transmitting the analog signals to the first-order modulation module and the second-order modulation module in the nonlinear modulation module to serve as intensity modulation coefficients of the first-order modulation module and the second-order modulation module in the equalization algorithm.
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