Device and method for monitoring simulation characteristics of optical transmitter, and optical transmitter

Abstract

The embodiment of the invention provides a device and a method for monitoring simulation characteristics of an optical transmitter, and the optical transmitter. The method comprises the following steps: inputting a first signal into a first electro-optical converter to obtain a to-be-measured optical signal; inputting the second signal into a second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined as a function of the first signal and an analog characteristic to be monitored of the first electro-optical converter; performing correlation processing on the optical signal to be measured and the modulation local signal to obtain at least one correlation quantity; an analog characteristic of the first electro-optic converter is estimated from the correlation quantity. Therefore, the analog characteristic information of the optical transmitter is extracted by using the correlation quantity of the optical signal to be measured and the modulated local signal, the required hardware cost is much lower than that of a conventional broadband receiver, and the power consumption is greatly reduced because complicated digital signal processing is not required.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical communication technology. Background Art

[0002] With the advancement of communication technology, transceiver analog characteristic imperfections are increasingly becoming the dominant impairment affecting the transmission performance of optical communication systems. Taking a 64GBaud 64QAM signal in a coherent optical communication system as an example, even a slight IQ (In-phase / Quadrature) amplitude imbalance (e.g., 0.5dB), IQ phase imbalance (e.g., 4°), or IQ skew (e.g., 0.7ps) in the transmitter can result in a 0.5dB optical signal-to-noise ratio (OSNR) penalty. Therefore, it is necessary to conveniently and accurately monitor analog characteristic imperfections in optical transmitters and then calibrate them.

[0003] Currently, optical transmitter imperfection estimation and compensation can be performed using a receiver equalizer, dynamically compensating and estimating transmitter imperfections at the receiver. However, this method is limited in the range of imperfections it can compensate and estimate, and operates after carrier phase recovery. This makes it susceptible to channel impairments, the receiver's optical signal-to-noise ratio, and the operating state of the receiver's digital signal processing (DSP), making it unstable.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of this application and for the convenience of understanding by those skilled in the art. It cannot be assumed that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology part of this application. Summary of the Invention

[0005] The inventors discovered that transmitter analog characteristic defects are located at the transmitter end, so compensation at the transmitter end is more effective than at the receiver end. Therefore, feeding the impairment coefficient estimated by the remote receiver back to the transmitter to compensate for analog characteristic defects would require additional communication resources and be inconvenient. Furthermore, deploying an additional full-featured broadband receiver at the transmitter end to monitor the transmitter analog characteristics would require high hardware cost and power consumption for the broadband receiver and high-speed analog-to-digital converter.

[0006] To address at least one of the aforementioned technical issues, embodiments of the present application provide an apparatus and method for monitoring analog characteristics of an optical transmitter, as well as an optical transmitter. Embodiments of the present application utilize low-speed optoelectronic and electrical components to perform correlation processing to obtain a correlation between a measured optical signal and a modulated local signal, and then calculate and estimate the analog characteristics of the measured transmitter based on the correlation.

[0007] According to one aspect of an embodiment of the present application, a device for monitoring analog characteristics of an optical transmitter is provided, comprising:

[0008] A first input unit, which inputs the first signal into the first electro-optical converter to obtain a light signal to be measured;

[0009] a second input unit, which inputs a second signal into a second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined according to the first signal and an analog characteristic to be monitored by the first electro-optical converter;

[0010] a correlation unit configured to perform correlation processing on the optical signal to be measured and the modulated local signal to obtain at least one correlation quantity;

[0011] An estimating unit estimates an analog characteristic of the first electro-optical converter according to the correlation amount.

[0012] According to another aspect of an embodiment of the present application, a method for monitoring analog characteristics of an optical transmitter is provided, comprising:

[0013] Inputting the first signal into the first electro-optical converter to obtain an optical signal to be measured;

[0014] Inputting a second signal into a second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined based on the first signal and an analog characteristic to be monitored by the first electro-optical converter;

[0015] Performing correlation processing on the optical signal to be measured and the modulated local signal to obtain at least one correlation quantity;

[0016] An analog characteristic of the first electro-optical converter is estimated based on the correlation quantity.

[0017] According to another aspect of an embodiment of the present application, an optical transmitter is provided, comprising a first electro-optical converter and a second electro-optical converter, wherein a first signal is input to the first electro-optical converter to obtain an optical signal to be measured; a second signal is input to the second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined based on the first signal and an analog characteristic to be monitored of the first electro-optical converter;

[0018] The optical transmitter further includes a monitoring device for performing correlation processing on the optical signal to be measured and the modulated local signal to obtain at least one correlation quantity; and estimating an analog characteristic of the first electro-optical converter according to the correlation quantity.

[0019] One of the beneficial effects of the embodiments of the present application is that the analog characteristic information of the optical transmitter is extracted by utilizing the correlation between the optical signal to be measured and the modulated local signal. The required hardware cost is much lower than that of a conventional broadband receiver, and since complex digital signal processing (DSP) is not required, power consumption is greatly reduced.

[0020] With reference to the following description and drawings, specific implementations of the embodiments of the present application are disclosed in detail, indicating how the principles of the embodiments of the present application can be employed. It should be understood that the embodiments of the present application are not limited in scope. Within the spirit and scope of the appended claims, the embodiments of the present application include many variations, modifications, and equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The included drawings are used to provide a further understanding of the embodiments of the present application, which constitute a part of the specification, are used to illustrate the implementation methods of the present application, and together with the text description, explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other implementation methods can be obtained based on these drawings without inventive work. In the drawings:

[0022] Figure 1 is a schematic diagram of a method for monitoring analog characteristics of an optical transmitter according to an embodiment of the present application;

[0023] Figure 2 Schematic diagram of a transmitter analog characteristic monitoring device based on parallel modulation correlation processing according to an embodiment of the present application;

[0024] Figures 3A to 3D is a schematic diagram of different types of first electro-optical converters according to an embodiment of the present application;

[0025] Figure 4A and Figure 4B is a schematic diagram of a first electro-optical converter with different polarization structures according to an embodiment of the present application;

[0026] Figures 5A to 5C is a schematic diagram of a first electro-optical converter with different modulation structures according to an embodiment of the present application;

[0027] Figures 6A to 6E is a schematic diagram of a second electro-optical converter of different types and structures according to an embodiment of the present application;

[0028] Figure 7 is a schematic diagram of the related processing of the embodiment of the present application;

[0029] Figure 8 is a possible output port of the first electro-optical converter of the embodiment of the present application;

[0030] 9A to 9D is a schematic diagram of an optoelectronic multiplier according to an embodiment of the present application;

[0031] Figure 10A and Figure 10B Schematic diagram of an electrical averaging unit with square wave multiplication and frequency shifting function added in an embodiment of the present application;

[0032] Figure 11A and Figure 11B is a schematic diagram of a first electro-optical converter and a second electro-optical converter according to an embodiment of the present application;

[0033] Figure 12 is a schematic diagram of a first electro-optical converter and a second electro-optical converter according to an embodiment of the present application;

[0034] Figure 13 is a schematic diagram of a first electro-optical converter and a second electro-optical converter according to an embodiment of the present application;

[0035] Figure 14 Schematic diagram of a transmitter analog characteristic monitoring device based on tandem modulation correlation processing according to an embodiment of the present application;

[0036] Figure 15 is a schematic diagram of a first electro-optical converter according to an embodiment of the present application;

[0037] Figure 16 is a schematic diagram of an embodiment of the present application based on tandem modulation and coherent detection;

[0038] Figure 17 is another schematic diagram of transmitter simulation characteristic monitoring according to an embodiment of the present application;

[0039] Figure 18 is a schematic diagram of a monitoring device for analog characteristics of an optical transmitter according to an embodiment of the present application;

[0040] Figure 19 Schematic diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0041] The foregoing and other features of the embodiments of the present application will become apparent through the following description with reference to the accompanying drawings. In the description and drawings, specific embodiments of the present application are disclosed in detail, which illustrate some embodiments in which the principles of the embodiments of the present application can be adopted. It should be understood that the present application is not limited to the described embodiments. On the contrary, the embodiments of the present application include all modifications, variations and equivalents that fall within the scope of the appended claims.

[0042] In the embodiments of the present application, the terms "first", "second", etc. are used to distinguish different elements from the name, but do not indicate the spatial arrangement or temporal order of these elements, and these elements should not be limited by these terms. The term "and / or" includes any one and all combinations of one or more of the associated listed terms. The terms "comprising", "including", "having", etc. refer to the presence of the stated features, elements, components or components, but do not exclude the presence or addition of one or more other features, elements, components or components.

[0043] In the embodiments of this application, the singular forms "a," "the," etc. include plural forms and should be broadly understood to mean "a" or "a type" rather than being limited to "one." Furthermore, the term "said" should be understood to include both singular and plural forms, unless the context clearly indicates otherwise. Furthermore, the term "according to" should be understood to mean "at least in part based on...", and the term "based on" should be understood to mean "at least in part based on...", unless the context clearly indicates otherwise.

[0044] Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments. The term "include / comprise" as used herein refers to the presence of a feature, an integral part, a step, or a component, but does not exclude the presence or addition of one or more other features, integral parts, steps, or components.

[0045] It is well known that correlation operation can achieve equivalent post-receiver sampling. Assume that there is an input pulse signal g(t), which is generated by a unit impulse pulse signal δ(t) through a shaping function g(t). The signal after passing through a receiver with an analog characteristic h′(t) can be expressed as Therefore, the sampling value of the received signal at time t0 is Similarly, assuming that there is another pulse signal h(t) at the transmitter, which is generated by a unit impulse pulse δ(t) passing through a filter with an analog characteristic h(t), the correlation function between the pulse signal g(t) and h(t) can be expressed as When the relative delay of pulses g(t) and h(t) is x=t0, the correlation function value is Obviously, if h′(t)=h(-t), that is, h′(t0-τ)=h(τ-t0), then r(t0)=G gh From this, we can see that the sampling of the signal at the receiving end after it passes through a receiver with an analog characteristic of h′(t) is equivalent to the correlation between the transmitting end and the pulse signal with an analog characteristic of h′(-t) at different time delays.

[0046] Based on this, the signal sent by an actual transmitter can be expressed as: E S (t)=∑ n A[n]g A[n] (t-nT), when the transmitter is linear, the shaped pulse g A[n] (t) is independent of the symbol transmitted or the preceding and following symbol sequence A[n]. If the transmitter has nonlinear effects, then the shaped pulse is no longer a constant pulse. Assuming that the analog characteristic of the receiver is h′(t), then the sample of the received signal at time τ is:

[0047]

[0048] Let h′(t)=h(-t), then ∫E S (t)h′(τ-t)dt=∫E S (t)h(t-τ)dt, the right side of the equal sign can also be understood as the transmitted signal E S (t) is correlated with h(t-τ). In other words, the correlation operation can achieve equivalent post-reception sampling.

[0049] Sampling a high-speed signal after reception obviously requires a high-speed receiver and a high-speed ADC, resulting in high hardware cost and power consumption. However, if the signal is converted to correlation, the integration operation is equivalent to averaging, which can be implemented using low-speed devices. The multiplication operation can be performed by leveraging the inherent physical properties of optical or optoelectronic devices. This allows the use of low-speed, low-power devices to implement an equivalent receiver.

[0050] Since the transmitted signal is a random signal, that is, E S (t)=∑ n A[n]g A[n] The symbol A[n] in (t-nT) is random. S The results obtained by correlating h(t) and h(t) are also random and cannot obtain the desired transmitter simulation characteristics.

[0051] In the embodiment of the present application, the local signal E can be modulated L (t)=∑ mB[m]h(t-mT), that is, the symbol sequence B[m] is transmitted by a transmitter with the analog characteristic h(t). B[m] is designed according to different monitoring purposes and the transmitted symbol A[m]. Calculate E S (t) and E L (t) related:

[0052]

[0053] in, h′(t)=h(-t),k=mn. (∑ n A[n]B[n+k]) is the cross-correlation characteristic of sequences A and B, which has a fixed value and is no longer random. Rx It contains the transmitter simulation characteristics that we want to monitor. When the signal to be measured A[n] has a good cross-correlation with the signal-related signal to be measured B[m], so When the signal to be measured A[n] has good cross-correlation with the signal-related signal to be measured B[m-1], so When the signal to be measured A[n] and the signal-related signal to be measured B[mx] have good cross-correlation, so

[0054] It can be seen that the correlation quantity represents the value of the impulse response of the cascade of the first and second electro-optical modulators at time t, where t depends on the relative delay between the signal to be measured and a signal related to the signal to be measured, or the relative delay between the optical signal to be measured and the modulated local signal. Therefore, when the monitoring target is the impulse response of the cascade of the first and second electro-optical converters, this response can be obtained through correlation processing; when the analog characteristics of the second electro-optical converter are known in advance, the analog characteristics of the first electro-optical converter can be calculated and inferred based on the correlation quantity; when the analog characteristics of the second electro-optical converter are unknown but do not change with time or environment, the correlation quantity can be used to monitor the changes in the analog characteristics of the first electro-optical converter over time or ambient temperature.

[0055] When a transmitter can be viewed as a superposition of multiple signals, such as the I and Q paths of a coherent transmitter, monitoring can be performed once for the I path and once for the Q path. By comparing the two monitoring results, even without knowing the analog characteristics of the second electro-optical converter, information about the differences between the I and Q paths, i.e., IQ imbalance, can still be obtained. This is because the second electro-optical converter has the same impact on both the I and Q paths. Similar situations also include horizontal and vertical polarization, differences in characteristics between different segments in a modulator composed of multiple segments, differences between different bit paths within a modulator, and differences in analog characteristics between different sub-DACs in a time-interleaving digital-to-analog converter (TI-DAC). Furthermore, under nonlinear conditions, differences in transmitter analog characteristics can be observed for different transmitted symbol sequences.

[0056] The above briefly describes the concept of the embodiments of the present application, and the following describes specific embodiments.

[0057] Embodiments of the first aspect

[0058] An embodiment of the present application provides a method for monitoring analog characteristics of an optical transmitter. Figure 1 FIG. 1 is a schematic diagram of a method for monitoring analog characteristics of an optical transmitter according to an embodiment of the present application. Figure 1 As shown, the method includes:

[0059] 101, inputting a first signal into a first electro-optical converter to obtain an optical signal to be measured;

[0060] 102. Input a second signal into a second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined based on the first signal and an analog characteristic to be monitored of the first electro-optical converter;

[0061] 103. Perform correlation processing on the optical signal to be measured and the modulated local signal to obtain at least one correlation quantity;

[0062] 104. Estimate analog characteristics of the first electro-optical converter according to the correlation quantity.

[0063] It is worth noting that the above Figure 1 The embodiments of the present application are only schematically described, but the present application is not limited thereto. For example, some of the above steps can be executed simultaneously or in sequence, the execution order of each operation can be adjusted appropriately, and other operations can be added or some operations can be reduced. Those skilled in the art can make appropriate modifications based on the above content, and are not limited to the above appended instructions. Figure 1 Records of.

[0064] In some embodiments, the correlation quantity represents a value of an impulse response of the cascade of the first electro-optical converter and the second electro-optical converter at a first moment, where the first moment depends on a relative delay between the first signal and the second signal.

[0065] In some embodiments, when at least two superimposed signals are sent to the transmitter, each signal is monitored at least once to obtain at least two correlation quantities, and the analog characteristics of the first electro-optical converter are estimated based on the at least two correlation quantities.

[0066] The following first describes the structure of the embodiment of the present application. There are many specific implementations of the related processing, which can be divided into parallel modulation-based and serial modulation-based according to the hardware structure relationship. The following first describes the solution based on parallel modulation.

[0067] In some embodiments, the first electro-optical converter and the second electro-optical converter are connected in parallel; the first electro-optical converter generates the optical signal to be measured based on the optical carrier and the first signal, and the second electro-optical converter generates the modulated local signal based on the optical carrier and the second signal; the optical signal to be measured and the modulated local signal are respectively input into an optoelectronic multiplier to obtain a product electrical signal; and the product electrical signal is electrically averaged to generate the at least one related quantity.

[0068] Figure 2 FIG is a schematic diagram of a transmitter simulation characteristic monitoring device based on parallel modulation correlation processing according to an embodiment of the present application. Figure 2 As shown, the device may include:

[0069] The first electro-optical converter 201 is the optical transmitter itself or only a part of the optical transmitter, and its analog characteristic is the target quantity to be monitored. The first electro-optical converter 201 generates the optical signal to be measured;

[0070] The second electro-optical converter 202 generates a modulated local signal according to the signal related to the optical signal to be measured. The modulated local signal has a certain correlation with the optical signal to be measured. The first electro-optical converter 201 and the second electro-optical converter 202 are in a parallel relationship.

[0071] A correlation processor 203 performs correlation processing on the optical signal to be measured and the modulated local signal based on low-speed optoelectronic and electrical devices to obtain a correlation value between the two signals;

[0072] The analog characteristic estimator 204 estimates the analog characteristic of the first electro-optical converter according to the signal correlation amount.

[0073] It is worth noting that Figure 2The structures for realizing monitoring of analog characteristics of optical transmitters are exemplarily described, but the present application is not limited to these structures. Appropriate modifications may be made to these structures, and the implementation methods of these modifications should all be included in the scope of the embodiments of the present application.

[0074] like Figure 2 As shown, the first electro-optical converter 201 modulates the test signal A[n] to be transmitted onto an optical carrier, generates a corresponding test optical signal and feeds it to the relevant processor 203. The first electro-optical converter 201 can be a complete optical transmitter or only a part of an optical transmitter.

[0075] It should be noted that this application does not impose any restrictions on the type and structure of the first electro-optical converter. For example, the physical material used may be lithium niobate, indium phosphide, silicon, etc. For example, it may be a coherent transmitter, an intensity modulation transmitter, a phase modulator, or a combined signal transmitter based on an optical frequency comb.

[0076] Figures 3A to 3D Schematic diagram of different types of first electro-optical converters according to an embodiment of the present application. The first electro-optical converter 201 can be any of the following: Figure 3A The coherent transmitter shown; Figure 3B Intensity modulator shown; Figure 3C The phase modulator shown; Figure 3D The combined signal transmitter based on optical frequency comb is shown.

[0077] For another example, the first electro-optical converter 201 may be a transmitter that outputs only a single-bias signal, or may be a transmitter that outputs a dual-bias signal.

[0078] Figure 4A and Figure 4B Schematic diagram of a first electro-optical converter with different polarization structures according to an embodiment of the present application. The first electro-optical converter 201 can be any of the following: Figure 4A The single-polarization electro-optical converter shown; Figure 4B The dual-polarization electro-optical converter shown.

[0079] For another example, the first electro-optical converter 201 can be based on a single-stage modulation structure or a segmented multi-stage modulation structure, and the segmented design type can be uniform and equal in length (such as thermometer coding type, Thermometer) or unequal in length (such as binary coding type, binary).

[0080] Figures 5A to 5C Schematic diagram of the first electro-optical converter with different modulation structures according to the embodiment of the present application. The first electro-optical converter 201 can be any of the following: Figure 5A The single-stage electro-optical converter shown; Figure 5B The multi-stage segmented electro-optical converter with a non-equal length segmented design structure is shown; Figure 5C The multi-stage segmented electro-optical converter shown has an equal-length segment design structure.

[0081] Assuming that the response of the first electro-optical converter is g(t), the generated optical signal to be measured can be simply expressed as E S (t)=∑ n A[n]g(t-nT), where T is the symbol period. The test signal A[n] can be a normal communication signal or another test signal designed as needed. For example, when testing the analog characteristics of a branch (I or Q) of a coherent transmitter, an all-0 signal can be sent to the other branch. Obviously, when A[n] is a normal communication signal, monitoring of the transmitter's analog characteristics can be performed without affecting normal communication signal transmission (in-service). When A[n] is a specially designed test signal, monitoring of the transmitter's analog characteristics can be performed before normal communication service begins (pre-service).

[0082] like Figure 2 As shown, the second electro-optical converter 202 loads the signal-to-be-measured related signal B[n] onto an optical carrier, generates a modulated local signal, and feeds it to the correlation processor 203. The second electro-optical converter 202 also has various types and structures. For example, it can be an MZ intensity modulator (MZM); an electro-absorption modulator (EAM); a phase modulator (PM); or a cascade of L (L ≥ 2) segment modulators of equal or unequal lengths, or a series connection of different types of modulators (e.g., an MZM or EAM and PM in series).

[0083] Figures 6A to 6E Schematic diagram of different types and structures of second electro-optical converters according to embodiments of the present application. The second electro-optical converter 202 can be any of the following: Figure 6A The MZ type intensity modulator with one segment is shown; Figure 6B The electroabsorption modulator shown; Figure 6C The phase modulator shown; Figure 6D The MZ-type intensity modulator shown has multiple segments of equal length; Figure 6E The electro-absorption modulator and the phase modulator are shown to be connected in series. When the second electro-optical converter 202 has only a limited number of states (eg, {1, 0, -1}, {1, -1}, {1, 0}), the second electro-optical converter 202 has the characteristics of low power consumption and high nonlinear tolerance.

[0084] Assuming that the response of the second electro-optical converter 202 is h(t), the generated modulated local signal can be simply expressed as EL (t)=∑ n B[n]h(t-nT). According to different monitoring targets, the signal-related signals to be measured can be selected in a variety of ways to generate different modulated local signals.

[0085] The first electro-optical converter and the second electro-optical converter are schematically described above. The second signal and the modulated local signal are described below. Figure 3A Taking the first electro-optical converter as an example, the specific measured signal related signal B[n] and the generated modulated local signal E are given for different analog characteristics. L (t).

[0086] In some embodiments, the analog characteristic is the frequency-independent IQ imbalance (IQimbalance) of the coherent transmitter; the first signal is A[n]=A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter respectively;

[0087] The second signal is and described and are successively input to the second electro-optical converter to generate a modulated local signal and

[0088] or,

[0089] The second signal is and described and are successively input to the second electro-optical converter to generate the modulated local signal and

[0090] In some implementations, the first signal or the second signal may be quantized using at least one bit, and the quantized signal may be input into the second electro-optical converter to obtain the modulated local signal.

[0091] For example, the monitoring target quantity is the static IQ imbalance of the coherent transmitter under in-service conditions, such as IQ amplitude imbalance and IQ phase imbalance. Here, "static" means that its characteristic is a scalar quantity and is independent of frequency. The signal to be measured can be expressed as A[n] = A I[n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter. At this time, the related signals of the signal to be measured can be selected as: and That is, load it twice and To the second electro-optical converter, generating a modulated local signal and

[0092] For another example, the monitoring target quantity is the static IQ imbalance of the coherent transmitter under in-service conditions, such as IQ amplitude imbalance and IQ phase imbalance. Here, "static" means that its characteristic is a scalar quantity and is independent of frequency. The signal to be measured can be expressed as A[n] = A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter. At this time, the related signals of the signal to be measured can be selected as: and 1,2,…,K, which can improve the measurement accuracy. Similarly, you can load it twice and To the second electro-optical converter, generating a modulated local signal and

[0093] For example, the monitoring target quantity is the static IQ imbalance of the coherent transmitter under in-service, such as IQ amplitude imbalance and IQ phase imbalance. Here, "static" means that its characteristics are scalar and independent of frequency. The signal to be measured can be expressed as A[n] = A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals applied to the I and Q branches of the coherent transmitter, respectively. The signal-related signal to be measured may also be a signal obtained by quantizing the signal to be measured or the signal-related signal to be measured using a finite number of bits. This generates a modulated local signal with only a finite number of states, which can reduce power consumption and hardware cost, and mitigate the effects of nonlinearity.

[0094] For example, when the signal to be tested A[n] is a normal 64QAM communication signal, A I [n] and A QThe value of [n] has 8 different states: {-7,-5,-3,-1,1,3,5,7}. There are only two value states {-1, 1}, which are represented by one bit quantization, that is, and Where sign() is the sign function:

[0095] sign(x)=1,ifx>0

[0096] sign(x)=-1,ifx<0

[0097] Similarly, the signal-related signal to be measured can also have only four value states {-3, -1, 1, 3}, which are quantized by two bits, that is, and Where Quan() is the quantization function:

[0098] Quan(x)=-3,if x=-7or-5

[0099] Quan(x)=-1,if x=-3or-1

[0100] Quan(x)=1,if x=1or3

[0101] Quan(x)=3,if x=5or7

[0102] For any other modulation format A[n], the above sign(x), Quan(x) or other similar functions can be used for finite bit quantization to generate a signal related to the signal to be measured. x can be the above A[n] I / Q [n] can also be the above or For example and or and For the sake of convenience, the modulated local signal generated based on the quantized signal-related signal to be measured is still expressed as

[0103] In some embodiments, the analog characteristic is an IQ skew of a coherent transmitter; the first signal is A[n]=A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter respectively;

[0104] The second signal is and described and are respectively input to the second electro-optical converter to generate a modulated local signal

[0105] For example, the monitoring target quantity is the IQ skew of the coherent transmitter under in-service. The signal to be measured can be expressed as A[n] = A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter. At this time, the related signals of the signal to be measured can be selected as: and That is, load it twice and To the second electro-optical converter, generating a modulated local signal The half symbol period delay This is achieved by adjusting the electrical delay or sampling clock phase.

[0106] For another example, the monitoring target quantity is the IQ skew of the coherent transmitter under in-service. The signal to be measured can be expressed as A[n] = A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter respectively. The signal related to the signal to be measured can also be a signal obtained by quantizing the signal to be measured or the signal related to the signal to be measured using a finite number of bits. In this way, the modulated local signal generated has only a finite number of states, which can reduce power consumption and hardware costs. For example, the above-mentioned sign(x), Quan(x) or other similar functions are used for finite bit quantization to generate the signal related to the signal to be measured. x can be A I / Q [n] can also be the above The specific quantization method will not be described here. Similarly, the generated modulated local signal can be expressed as m is an even number or m is an odd number.

[0107] In some embodiments, the analog characteristic is a frequency-dependent IQ imbalance (IQimbalance) of a coherent transmitter; the first signal is A[n]=A I [n]+jA Q [n], where AI [n] and A Q [n] respectively represent the signals loaded onto the I branch and Q branch of the coherent transmitter;

[0108] The second signal is The and are respectively input into the second electro-optic converter to generate a modulated local signal where q is an integer, Y is an empirical value selected according to the simulation characteristics of the transmitter under test, and τ is a unit time delay less than T;

[0109] Or,

[0110] When (q - 1)τ = mT + δ, 0 ≤ δ < T, the second signal is The and are respectively input into the second electro-optic converter to generate a modulated local signal

[0111] For example, the monitored target quantity not only includes the above-mentioned in-service coherent transmitter static IQ imbalance (IQ amplitude imbalance, IQ phase imbalance, and IQ skew), but also includes the in-service coherent transmitter frequency-dependent IQ imbalance, such as the IQ two-channel frequency response difference. The test signal can be expressed as A[n] = A I [n] + jA Q [n], where A I [n] and A Q [n] respectively represent the signals loaded onto the I branch and Q branch of the coherent transmitter. At this time, the modulated local signal is: and where q is an integer, Y is an empirical value selected according to the simulation characteristics of the transmitter under test, τ is a unit time delay less than T, such as or or others. For each q value, the signal needs to be loaded once, and then and are loaded into the second electro-optic converter in two batches successively. At this time, can be selected, and the time delay (q - 1)τ is only achieved by adjusting the electrical time delay, that is In addition, when (q - 1)τ = mT + δ, 0 ≤ δ < T, it can also be made that At this time, there is The time delay δ is achieved by adjusting the electrical time delay or the sampling clock phase.

[0112] For another example, the monitoring target quantity includes not only the static IQ imbalance (IQ amplitude imbalance, IQ phase imbalance and IQ skew) of the coherent transmitter under in-service, but also the frequency-related IQ imbalance of the coherent transmitter under in-service, such as the difference in the frequency response of the two IQ paths. The signal to be measured can be expressed as A[n] = A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter respectively. The signal related to the signal to be measured may also be a signal obtained by quantizing the signal to be measured or the signal related to the signal to be measured using a finite number of bits.

[0113] In some embodiments, the analog characteristic is a frequency-independent difference between different segments or different combinations of segments allocated according to bits within the transmitter; the first signal is a signal A loaded onto the segment or segment combination allocated to the jth bit. (j) [n];

[0114] The second signal is described are respectively input to the second electro-optical converter to generate the modulated local signal

[0115] or,

[0116] The second signal is described are respectively input to the second electro-optical converter to generate the modulated local signal

[0117] For example, the monitoring target quantity is the static analog characteristic difference (amplitude) between different segments or the overall combination of segments allocated by bits in the in-service transmitter. The signal to be measured can be expressed as A (j) [n] is the signal loaded on the segment or segment combination assigned to the jth bit, and its value state is {-1,1}, {1,0} or {-1,0}. At this time, the monitoring signal related signals can be selected as: That is, respectively Loaded to the second electro-optical converter to generate a modulated local signal

[0118] For another example, the monitoring target quantity is the static analog characteristic difference (amplitude) between different segments or the overall combination of segments allocated by bits in the transmitter under in-service. The signal to be measured can be expressed as A (j) [n] is the signal loaded on the segment or segment combination assigned to the jth bit, and its value state is {-1,1}, {1,0} or {-1,0}. At this time, the monitoring signal related signals can be selected as: Can improve the measurement accuracy, similarly, respectively Loaded to the second electro-optical converter to generate a modulated local signal

[0119] For example, the monitoring target quantity is the static analog characteristic difference (amplitude) between different segments or the overall combination of segments allocated by bits in the transmitter under in-service. The signal to be measured can be expressed as A (j) [n] is the signal loaded onto the segment or segment combination assigned to the jth bit, and can take the value of {-1, 1}, {1, 0}, or {-1, 0}. In this case, the signal-related signal to be measured can also be a signal obtained by quantizing the signal to be measured or the signal-related signal to be measured using a finite number of bits.

[0120] In some embodiments, the analog characteristic is a skew difference between different segments or different segment combinations according to bit allocation in the transmitter; the first signal is a signal A loaded on the segment or segment combination allocated to the jth bit. (j) [n];

[0121] The second signal is described are respectively input to the second electro-optical converter to generate the modulated local signal

[0122] For example, the monitoring target quantity is the static analog characteristic difference (skew) between different segments or the overall combination of segments allocated by bits in the in-service transmitter. The signal to be measured can be expressed as A (j) [n] is the signal loaded on the segment or segment combination to be tested assigned to the jth bit, and its value state is {-1,1}, {1,0} or {-1,0}. At this time, the related signals of the signal to be tested can be selected as: That is, loading in sequence to the second electro-optical converter, the generated modulated local signal can be expressed as m is an even number or m is an odd number, the half-symbol period time delay is achieved by adjusting means such as the electrical time delay or the sampling clock phase.

[0123] For another example, the monitored target quantity is the static analog characteristic difference (skew) between different segments or segment combinations allocated by bits in the in-service transmitter as a whole. The signal to be measured can be expressed as A (j) [n], which is the signal loaded onto the segment or segment combination to be measured allocated to the j-th bit, and the value state is {-1, 1}, {1, 0} or {-1, 0}. At this time, the signal related to the signal to be measured can also be the signal obtained by quantifying the signal to be measured or the above-mentioned signal related to the signal to be measured using a finite number of bits.

[0124] In some embodiments, the analog characteristic is the frequency-related difference between different segments (segments) allocated by bits in the transmitter or between different segment combinations; the first signal is the signal A (j) [n] loaded onto the segment or segment combination allocated to the j-th bit;

[0125] The second signal is The are respectively input to the second electro-optical converter to generate the modulated local signal q is an integer, Y is an empirical value selected according to the analog characteristics of the transmitter to be measured, and τ is a unit time delay less than T;

[0126] Or,

[0127] When (q - 1)τ = mT + δ, 0 ≤ δ < T, the second signal is The are respectively input to the second electro-optical converter to generate the modulated local signal

[0128] For example, the monitored target quantity not only includes the static analog characteristic differences (amplitude and phase imbalance, skew) between different segments or segment combinations allocated by bits in the in-service transmitter as a whole, but also includes frequency-related differences, such as the frequency response differences between different segments or segment combinations allocated by bits as a whole. The signal to be measured can be expressed as A (j)[n] is the signal loaded onto the segment or segment combination to be measured assigned to the j-th bit, and its value states are {-1, 1}, {1, 0} or {-1, 0}. At this time, the modulated local signal is: q is an integer, Y is an empirical value selected according to the analog characteristics of the transmitter to be measured, τ is the unit time delay less than T, or or others. For each q value, the signal needs to be loaded once and then loaded in multiple batches to the second electro-optic converter. If the transmitter contains a total of J bits, then the number of batches will also be J. At this time, it can be selected and the time delay (q - 1)τ is only achieved by adjusting the electrical time delay, that is In addition, when (q - 1)τ = mT + δ, 0 ≤ δ < T, it can also be selected At this time, there is δ is achieved by adjusting the electrical time delay or the sampling clock phase.

[0129] For another example, the monitored target quantity not only includes the static analog characteristic differences (amplitude and phase imbalance, skew) between the different segments or segment combinations assigned by bit in the transmitter under in-service as described above, but also includes frequency-related differences, such as the frequency response differences between the different segments or segment combinations assigned by bit. The signal to be measured can be expressed as A (j) [n] is the signal loaded onto the segment or segment combination to be measured assigned to the j-th bit, and its value states are {-1, 1}, {1, 0} or {-1, 0}. At this time, the signal related to the signal to be measured can also be the signal obtained by quantifying the signal to be measured or the above-mentioned signal related to the signal to be measured using a finite number of bits.

[0130] In some embodiments, the analog characteristic is the difference between the different polarization states as a whole in the dual-polarization transmitter or between different segments (segments) assigned by bit within different polarization states or between different segment combinations;

[0131] H and V respectively represent the H polarization state and V polarization state of the dual-polarization transmitter, and the second signals of the H path and V path of the dual-polarization transmitter are respectively and

[0132] For example, if the monitoring target is the analog characteristic difference (amplitude, skew or frequency response difference) between different polarization states of the dual-bias transmitter as a whole or different segments or segment combinations allocated by bits in different polarization states under in-service, the appropriate signal B to be measured can be selected according to the above processing method. 1～8 [n], these signals can be uniformly recorded as To generate the corresponding modulated local signal Here we will not elaborate on this. H and V represent the H polarization state and V polarization state of the dual-bias transmitter, that is, the polarization state is selected according to the H and V path signals to be measured of the dual-bias transmitter. and

[0133] In some embodiments, the analog characteristic is an analog characteristic of the first electro-optical converter under a specific symbol or a specific symbol sequence; the first signal is represented by A[n], and the second signal B 10 [n] is a constant when corresponding to the specific symbol, or the second signal B 11 [n] is a constant when corresponding to the central symbol of the specific symbol sequence, and the modulated local signal is a pulse signal.

[0134] For example, the monitoring target quantity is the analog characteristics of the first electro-optical converter under a specific symbol or a specific symbol sequence under in-service (for example, for a coherent transmitter, consider any single I branch or Q branch; for a dual-bias intensity modulation transmitter, consider any polarization state branch; for a dual-bias coherent transmitter, consider any single I branch or Q branch in any polarization state). For example, assuming that the signal to be measured A[n] is a PAM8 signal, each symbol in A[n] is a random one of {-7, -5, -3, -1, 1, 3, 5, 7}. At this time, a suitable signal related to the signal to be measured can be selected so that the generated modulated local signal is a pulse signal. For example, when the monitoring target quantity is the analog characteristics of the first electro-optical converter under the input symbol [-3], the signal to be measured can be selected as B 10 [n], specifically

[0135] B 10 [n]=C if A[n]=-3

[0136] B 10 [n]=0 if A[n]≠-3

[0137] Where C is a constant, which can be 1 or other non-zero constants. For any other specific symbols, the same analogy is applied and will not be repeated here. The generated modulated local signal is recorded as

[0138] For another example, the monitoring target quantity is the analog characteristic of the first electro-optical converter under the input symbol sequence of [7 1 5], and the signal to be measured can be selected as B 11 [n], specifically

[0139] B 11 [n]=C if A[n-1]=7and A[n]=1and A[n+1]=5

[0140] B 11 [n]=0 if A[n-1]≠7or A[n]≠1or A[n+1]≠5

[0141] Similarly, where C is a constant, it can be 1 or other non-zero constants. For any other specific symbol sequence of length 3 or longer, and so on, we will not repeat it here. We will not repeat it here. The generated modulated local signal is recorded as

[0142] It should be noted that all the signals to be measured are related to the signal B 1～11 [n] No real-time loading is required, that is, it is opened after a period of time T1 and lasts for T2, that is,

[0143] B 1～11 [n]=0 if m(T1+T2)≤t <m(T1+T2)+T1,m=0,1,2,…

[0144] B 1～11 [n]=B 1～11 [n]if m(T1+T2)+T1≤t<(m+1)(T1+T2),m=0,1,2,…

[0145] In this way, the overall monitoring power consumption can be reduced.

[0146] For example, the monitoring target quantity is the various target quantities to be measured in the transmitter under pre-service. The test signal can be a specially designed test signal with no limit on the value state. For example, for a coherent transmitter, if the analog characteristics of I channel are tested, A Q [n] = 0; For a modulator with a segment cascade structure, if the analog characteristics of the segment or segment combination assigned to the zth bit are tested, A (j) [n]=0,j≠z, thus completely avoiding the interference introduced by the non-measurement segment or segment combination. The signal related to the signal to be measured can still use the above signal B 1 ～11 [n] is selected, which will not be described here.

[0147] In some embodiments, the simulation characteristics are the static and dynamic simulation characteristics of each segment in a transmitter with a cascaded structure of multiple segment modulators; the first signal of the segment to be measured is A (s) [n], and the first signal of the non-segment to be measured is A (w) [n] = 0, w ≠ s;

[0148] The second signal is The Are respectively input into the second electro-optical converter to generate the modulated local signal q is an integer, and τ is a unit time delay less than T;

[0149] Or,

[0150] When (q - 1)τ = mT + δ, 0 ≤ δ < T, the second signal is The Are respectively input into the second electro-optical converter to generate the modulated local signal

[0151] For example, if the monitoring target is the static and dynamic simulation characteristics of each segment in a transmitter with a cascaded structure of multiple segment modulators, all segments can be tested one by one in the pre-service stage. For example, when the object to be measured is the s-th segment, the test signal can be expressed as A (w) [n] = 0, w ≠ s, that is, all other non-segment to be measured send all-zero signals or are turned off and do not work, while the test signal A on the segment to be measured (s) [n] is any random signal with good autocorrelation characteristics. At this time, the modulated local signal is: q is an integer, τ is a unit time delay less than T, Or Or others. For each q value, the signal needs to be loaded once, and then loaded in multiple batches To the second electro-optical converter. If the transmitter contains a total of S segments, then the number of batches will also be S. At this time, you can choose And the time delay (q - 1)τ is only achieved by adjusting the electrical time delay, that is In addition, when (q - 1)τ = mT + δ, 0 ≤ δ < T, you can also choose At this time there is δ is achieved by adjusting the electrical time delay or the sampling clock phase.

[0152] The above schematically illustrates the second signal and the modulated local signal. Figure 2 Describes the relevant processor.

[0153] like Figure 2 As shown, the relevant processor 203 processes the optical signal E to be measured output by the first electro-optical converter 201 based on the low-speed optoelectronic and electrical devices. s (t) and the modulated local signal E output by the second electro-optical converter 202 L (t) Perform correlation processing to obtain the correlation between the two signals:

[0154]

[0155] There are various ways to implement correlation processing operations based on parallel modulation. The following uses the first electro-optical converter in Figures 3, 4, and 5, and the second electro-optical converter in Figure 6, as examples to illustrate specific implementations for different target monitoring quantities. When the target monitoring quantity is the analog characteristics of an in-service transmitter, the correlation processor can be implemented as follows.

[0156] In some embodiments, the first electro-optical converter is a coherent transmitter.

[0157] Figure 7 FIG. 1 is a schematic diagram of the related processing of an embodiment of the present application, showing the related processing for monitoring the IQ imbalance of a coherent transmitter when the first electro-optical converter is a coherent transmitter. Figure 7 As shown, a portion of the DC light is split before the modulator and transmitted to the second electro-optical converter. The relevant processor is implemented based on an optoelectronic multiplier and an electrical averaging unit.

[0158] like Figure 7 As shown, the optoelectronic multiplier includes an optional phase shifter (i.e. The electrical averaging unit includes a low-pass filter and a low-speed ADC. The electrical averaging operation can be implemented in the analog domain or the digital domain. When the electrical averaging operation is implemented in the analog domain, the low-speed ADC outputs the average value of the monitoring voltage.<V1(t)> and<V2(t)> When the electrical averaging operation is implemented in the digital domain, the low-speed ADC outputs the monitoring voltage signals V1(t) and V2(t), and then the digital averaging method is used to obtain<V1(t)> and<V2(t)> .

[0159] The output optical signal of the coherent transmitter is denoted as E S (t) = E S-I (t)+jE S-Q (t), the output signal of the second photoelectric converter is recorded as EL (t), the phase difference between them is recorded as After an ideal 90-degree mixer, the output optical signal can be expressed as:

[0160]

[0161] Then, the balanced photodetector (BPD) output current can be expressed as

[0162]

[0163]

[0164] Among them, R BPD represents the response of the balanced photodetector, Indicates a constant phase. When E L (t) = E L-I (t)=∑ n B I [n]h(t-nT), E L (t) and A I [n] related, that is, related to E S-I (t) related, the output of the photoelectric multiplier I BPD1 (t) and I BPD2 (t) contains E L (t)E S-I (t) information, through the electrical averaging unit, the correlation between the two signals can be obtained and Similarly, when E L (t) = E L-Q (t), the correlation value V1 of the two signals can be obtained Q and When E L (t) is the delayed signal E L (t-(q-1)τ), the obtained correlation quantity can also be expressed as and For different modulated local signals, corresponding correlation quantities can be obtained respectively in this way.

[0165] It should be noted that Figure 7 The embodiment shown is only a framework example, and specific details of each unit may be different.

[0166] Figure 8 is a possible output port of the first electro-optical converter in the embodiment of the present application. For example, the output signal of the first electro-optical converter is Figure 7The other branch output signal I-jQ of the 2*2 multi-mode interference coupler (Multi-mode Interference Coupler, MMI) can also be Figure 8 The normal output signal I+jQ of the transmitter or the output of its monitoring branch is shown.

[0167] 9A to 9D Schematic diagram of the photoelectric multiplier of the embodiment of the present application. The photoelectric multiplier can be implemented in many ways, such as Figure 9A As shown, an optional phase shifter, a 90-degree hybrid and two balanced photodetectors are used; Figure 9B As shown, a phase shifter, 180-degree hybrid and two single photodetectors are used; Figure 9C As shown, an optional phase shifter, 120-degree hybrid and three single photodetectors are used; Figure 9D As shown, a phase shifter, a coupler and a single photodetector are used.

[0168] Figure 10A and Figure 10B This is a schematic diagram of an electrical averaging unit with square wave multiplication and frequency shifting function added to an embodiment of the present application. The electrical averaging operation can be implemented in the analog domain or the digital domain. For example, by using a low-pass filter or mathematically averaging the signal after low-speed ADC sampling. In addition, square wave multiplication and frequency shift can be introduced, and a 125MHz square wave can be used to multiply the signal related to the signal to be measured and the product signal at the same time. In this way, the relevant quantity can be transferred from DC to the 125MHz frequency, thereby avoiding 1 / f noise near DC. Figure 10A As shown, the multiplication with the product signal can be performed in the analog domain, as Figure 10B As shown, it can also be performed in the digital domain, and the embodiments of the present application do not impose specific restrictions on this.

[0169] In some embodiments, the first electro-optical converter is a segment or a combination of segments allocated by bits in the coherent transmitter. The second electro-optical converter is an independent electro-optical converter as shown in FIG6 . In this case, the related processing implementation can still be adopted. Figure 7 The embodiment shown.

[0170] Figure 11A and Figure 11B Schematic diagram of the first electro-optical converter and the second electro-optical converter of the embodiment of the present application, showing that the first electro-optical converter is a segment allocated by bit in the coherent transmitter (such as Figure 11A As shown) or segment combination (as Figure 11B The relationship between the first electro-optical converter and the second electro-optical converter is shown in FIG. 9 . The obtained correlation quantity is recorded as and j represents the segment or segment combination to which the jth bit to be measured is allocated. This method can be used to obtain the correlation value for local signals with different modulations.

[0171] In some embodiments, the first electro-optical converter is an MZM intensity modulator or a segment or a segment combination thereof allocated by bits therein. The second electro-optical converter is an independent electro-optical converter as shown in FIG6 .

[0172] Figure 12 This is a schematic diagram of the first electro-optical converter and the second electro-optical converter of the embodiment of the present application, showing that the first electro-optical converter is an MZM intensity modulator or a segment or segment combination thereof allocated by bits, and the second electro-optical converter is an independent electro-optical converter. Figure 12 As shown, the photoelectric multiplier consists of a single photodetector. This method can be used to obtain correlation quantities for different modulated local signals. Where j represents the segment or segment combination assigned to the jth bit to be measured.

[0173] In some embodiments, the first electro-optical converter is a dual-bias transmitter, and the second electro-optical converter is the independent electro-optical converter shown in Figure 6. The overall analog characteristics of different polarization states can be monitored according to the aforementioned embodiments. When the first electro-optical converter is a dual-bias transmitter with different segments or combinations of segments allocated by bit within each polarization state, and the second electro-optical converter is the independent electro-optical converter shown in Figure 6, each polarization state can be monitored according to the aforementioned embodiments. Correlation quantities obtained for different modulated local signals are not further described here.

[0174] When the monitoring target quantity is the analog characteristic of the transmitter under pre-service, the above embodiment can be used to perform correlation processing on the modulated local signal and the signal to be measured. The present application is not limited to the above embodiment, and the following manner can also be used.

[0175] Figure 13 This is a schematic diagram of the first electro-optical converter and the second electro-optical converter of an embodiment of the present application. The first electro-optical converter is any segment or segment combination in the coherent transmitter, and the second electro-optical converter is a segment or segment combination or the entire parallel branch in the coherent transmitter that is parallel to the first electro-optical converter. The difference from the typical coherent transmitter configuration is that the phase difference between the I path and the Q path is 0 degrees, which can achieve Figure 2 The first electro-optical converter and the second electro-optical converter are shown in FIG. In this case, the photoelectric multiplier can be composed of only a single photodetector, and the correlation value V is obtained by electrical averaging operation.j [q]. This method can be used to obtain the correlation quantity for different modulated local signals, which will not be described in detail here.

[0176] The above schematically illustrates the relevant processors, and the following returns to Figure 2 The simulation characteristic estimator 204 is described below. The simulation characteristic estimator 204 can estimate the corresponding target monitoring quantity based on all the related quantities mentioned above.

[0177] For example,

[0178] i) For and The IQ magnitude imbalance can be calculated as:

[0179]

[0180] The phase imbalance is:

[0181]

[0182] ii) For and C1 and C2 can be determined by pre-calibration in the pre-service stage.

[0183] iii) For and matrix The transfer function of the transmitter under test is directly indicated, and the IQ amplitude imbalance, IQ phase imbalance, IQ skew and frequency-related imbalance between IQ can be directly calculated according to existing technologies.

[0184] for and as well as and The analog characteristic differences between the corresponding segments or segment combinations can be calculated by referring to i), ii), and iii), which will not be repeated here.

[0185] The correlation value obtained for the signal under test obtained after quantization processing using a limited number of bits is and The corresponding simulation characteristic differences can also be calculated according to i), ii) and iii), which will not be repeated here.

[0186] for and or V 9-H [q] and V 9-V[q], the imbalance between corresponding polarization states or the imbalance between different segments within a polarization state can also be calculated by referring to the above content.

[0187] For V i | i＝10～11 , which directly indicates the analog characteristics of the first electro-optical converter to be tested under a specific symbol or a specific symbol sequence.

[0188] For V i [q]| i＝12 , which itself indicates the analog characteristics of the segment or segment combination to be tested.

[0189] The above Figure 2 The parallel modulation is schematically illustrated as an example, and the series modulation is explained below.

[0190] In some embodiments, the first electro-optical converter and the second electro-optical converter are connected in series; the first electro-optical converter generates the optical signal to be measured based on the optical carrier and the first signal, and the second electro-optical converter generates the modulated local signal based on the optical signal to be measured and the second signal; the modulated local signal is input to the photoelectric converter to obtain an electrical signal; and the electrical signal is electrically averaged to generate the at least one related quantity.

[0191] Figure 14 FIG is a schematic diagram of a transmitter analog characteristic monitoring device based on serial modulation correlation processing according to an embodiment of the present application. Figure 14 As shown, the device may include:

[0192] The first electro-optical converter 1401 is the optical transmitter itself or only a part of the optical transmitter, and its analog characteristic is the target quantity to be monitored. The first electro-optical converter 1401 generates the optical signal to be measured;

[0193] A second electro-optical converter 1402 generates an optical product signal according to the signal-related signal to be measured, and implements a product operation of the optical signal to be measured and the signal-related signal to be measured in the optical domain;

[0194] The photoelectric converter 1403 converts the optical product signal into an electrical signal;

[0195] The electrical averaging unit 1404 performs electrical averaging on the electrical signal output by the photoelectric converter to obtain a correlation value between the signal to be measured and a signal related to the signal to be measured;

[0196] The analog characteristic estimator 1405 estimates the analog characteristic of the first electro-optical converter according to the signal correlation amount.

[0197] It is worth noting that Figure 14The structures for realizing monitoring of analog characteristics of optical transmitters are exemplarily described, but the present application is not limited to these structures. Appropriate modifications may be made to these structures, and the implementation methods of these modifications should all be included in the scope of the embodiments of the present application.

[0198] like Figure 14 As shown, first electro-optical converter 1401 generates a measured optical signal corresponding to measured signal A[n] through modulation and inputs it into second electro-optical converter 1402. First electro-optical converter 1401 can be a complete optical transmitter or only a portion of it. It should be noted that the present embodiment imposes no restrictions on the type and structure of first electro-optical converter 1401. For example, it can have variations as shown in Figures 3, 4, and 5, or it can be a directly modulated laser.

[0199] Figure 15 is a schematic diagram of a first electro-optical converter according to an embodiment of the present application. Figure 15 As shown, the first electro-optical converter may be a directly modulated laser (DML or EML).

[0200] Assuming that the response of the first electro-optical converter is g(t), the generated optical signal to be measured can be expressed as E S (t)=∑ n A[n]g(t-nT). The test signal A[n] can be a normal communication signal or other test signal designed as needed. For example, when testing the analog characteristics of a branch (I or Q) of a coherent transmitter, an all-0 signal can be sent to the other branch. Obviously, when A[n] is a normal communication signal, the monitoring of the analog characteristics of the transmitter can be carried out without affecting the normal communication signal transmission (in-service); when A[n] is a specially designed test signal, the analog characteristics of the transmitter can be monitored before the normal communication service begins (pre-service).

[0201] like Figure 14 As shown, the second electro-optical converter 1402 adds the signal-to-be-measured correlation signal B[n] to the optical signal to be measured, generating an optical product signal. This is done by directly multiplying the optical signal to be measured and the signal-to-be-measured correlation signal in the optical domain via serial modulation. Serial modulation is a natural product operation. The optical product signal can essentially still be considered a modulated local signal.

[0202] The type and structure of the second electro-optical converter 1402 can also be in various forms, and can be varied as shown in FIG6 . Furthermore, depending on the target quantity being monitored, the signal-to-be-measured related signal B[n] can also be selected in a variety of ways to generate different optical product signals, and this embodiment of the present application does not impose any specific restrictions on this.

[0203] It should be noted that all monitoring target quantities mentioned in the parallel modulation correlation processing and the corresponding given measured signal correlation signal B 1～12 [n] is applicable in this case. The difference is that the output signal of the second electro-optical converter is the optical product signal h(t) still represents the response of the second electro-optical converter.

[0204] like Figure 14 As shown, the photoelectric converter 1403 converts the optical product signal into an electrical signal. Depending on the monitoring target quantity, there are multiple series modulation and photoelectric conversion (detection) methods.

[0205] Figure 16 FIG is a schematic diagram of an embodiment of the present application based on serial modulation and coherent detection. Figure 16 As shown, the optical-to-electrical converter includes an optional phase shifter (optional means it can be present or absent), a 90-degree mixer and a balanced photodetector to convert the optical domain product signal into an electrical signal. Figure 16 A framework example is shown illustratively, and the photoelectric converter may also have variations as shown in FIG9 .

[0206] When the monitoring target quantity is the analog characteristic difference between each segment or segment combination in the transmitter, or when the monitoring target quantity is the analog characteristic difference (amplitude, skew or frequency response difference) between different polarization states as a whole or each segment or segment combination in different polarization states in a dual-bias transmitter, or when the monitoring target quantity is the analog characteristic of the first electro-optical converter under a specific symbol or symbol sequence, analog characteristic monitoring can be performed according to the above-mentioned embodiment.

[0207] Figure 17 FIG. 1 is another schematic diagram of transmitter simulation characteristic monitoring according to an embodiment of the present application. If the first electro-optical converter is a directly modulated laser, it can be as follows: Figure 17 Direct monitoring shown.

[0208] The above schematically illustrates the method for monitoring the analog characteristics of an optical transmitter and the partial hardware structure for implementing the method, but the present application is not limited thereto. The monitoring method may also include other steps or processes. For the specific content of these steps or processes, reference may be made to the prior art. In addition, the above exemplary description of the hardware structure for implementing the monitoring method is provided, but the present application is not limited to these hardware structures. Appropriate variations of these structures may also be made, and the implementation of these variations should all be included within the scope of the embodiments of the present application.

[0209] In an embodiment of the present application, a first electro-optical converter (the transmitter itself or a part of the transmitter) generates a light signal to be measured, and a second electro-optical converter generates different modulated local signals according to different monitoring target quantities. The relevant processor uses low-speed optoelectronic and electrical devices to complete the relevant operations of the light signal to be measured and the modulated local signal, and calculates the analog characteristics of the transmitter based on the relevant quantities of the light signal to be measured and the modulated local signal.

[0210] In the embodiments of the present application, correlation operations can be performed in both parallel and serial schemes. In the parallel scheme, the optical signal to be measured and the modulated local signal are added in the optical domain, and multiplication and averaging in the electrical domain are performed using an optoelectronic converter. In the serial scheme, the second electro-optical modulator directly modulates the optical signal to be measured, performing multiplication of the optical signal to be measured and a correlation signal of the optical signal to be measured in the optical domain. Averaging is then performed in the electrical domain.

[0211] In the embodiments of the present application, there are still many ways to implement the optical-to-electrical converter, such as 90° hybrid coherent receiver, 180° hybrid and balanced photodetector, 120° hybrid and single photodetector, etc. Multiplication in the optical domain can be achieved by serial modulation.

[0212] In an embodiment of the present application, when the monitored target quantity is static analog characteristic imbalance (amplitude, phase and skew), the generated modulated local signal can be only a single signal; when the monitored target quantity is frequency-related analog characteristic difference, the generated modulated local signal can be a signal containing multiple different delays.

[0213] In the embodiment of the present application, when the second electro-optical converter has only a limited number of states, it can have the advantage of reducing the power consumption and hardware cost of the entire monitoring device.

[0214] The above embodiments are merely exemplary of the present invention, but the present invention is not limited thereto. Appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0215] As can be seen from the above embodiments, the hardware cost required to extract the analog characteristic information of the optical transmitter by using the correlation between the optical signal to be measured and the modulated local signal is much lower than that of a conventional broadband receiver, and since complex DSP processing is not required, the power consumption is greatly reduced.

[0216] Embodiments of the second aspect

[0217] An embodiment of the present application provides an optical transmitter simulating a specific monitoring device, and the contents that are the same as those in the embodiment of the first aspect will not be repeated.

[0218] Figure 18FIG. 1 is a schematic diagram of a monitoring device for analog characteristics of an optical transmitter according to an embodiment of the present application. Figure 18 As shown, the monitoring device for the analog characteristics of the optical transmitter includes:

[0219] A first input unit 1801 inputs the first signal to a first electro-optical converter to obtain an optical signal to be measured;

[0220] A second input unit 1802 inputs a second signal to a second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined according to the first signal and an analog characteristic to be monitored by the first electro-optical converter;

[0221] a correlation unit 1803, configured to perform correlation processing on the optical signal to be measured and the modulated local signal to obtain at least one correlation quantity;

[0222] An estimating unit 1804 is configured to estimate an analog characteristic of the first electro-optical converter according to the correlation quantity.

[0223] In some embodiments, the correlation quantity represents a value of an impulse response of the cascade of the first electro-optical converter and the second electro-optical converter at a first moment, where the first moment depends on a relative delay between the first signal and the second signal.

[0224] In some embodiments, when at least two superimposed signals are sent to the transmitter, each signal is monitored at least once to obtain at least two correlation quantities, and the analog characteristics of the first electro-optical converter are estimated based on the at least two correlation quantities.

[0225] In some embodiments, the analog characteristic is the frequency-independent IQ imbalance of the coherent transmitter; the first signal is A[n]=A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter respectively;

[0226] The second signal is and described and are respectively input to the second electro-optical converter to generate a modulated local signal and

[0227] or,

[0228] The second signal is and The and are respectively input into the second electro-optical converter to generate the modulated local signal and

[0229] In some embodiments, the analog characteristic is the IQ skew of a coherent transmitter; the first signal is A[n]=A I [n]+jA Q [n], where A I [n] and A Q [n] respectively represent the signals loaded onto the I branch and Q branch of the coherent transmitter;

[0230] The second signal is and The and are respectively input into the second electro-optical converter to generate the modulated local signal

[0231] In some embodiments, the analog characteristic is the frequency-dependent IQ imbalance of a coherent transmitter; the first signal is A[n]=A I [n]+jA Q [n], where A I [n] and A Q [n] respectively represent the signals loaded onto the I branch and Q branch of the coherent transmitter;

[0232] The second signal is The and are respectively input into the second electro-optical converter to generate the modulated local signal q is an integer, Y is an empirical value selected according to the analog characteristic of the transmitter under test, and τ is a unit time delay less than T;

[0233] Or,

[0234] When (q - 1)τ = mT + δ, 0 ≤ δ < T, the second signal is The and are respectively input into the second electro-optical converter to generate the modulated local signal

[0235] In some embodiments, the analog characteristic is a frequency-independent difference between different segments or different combinations of segments allocated according to bits in a transmitter; the first signal is signal A loaded onto the segment or segment combination allocated to the j-th bit (j) [n];

[0236] The second signal is The Are respectively input into the second electro-optical converter to generate the modulated local signal

[0237] Or,

[0238] The second signal is The Are respectively input into the second electro-optical converter to generate the modulated local signal

[0239] In some embodiments, the analog characteristic is a skew difference between different segments or different combinations of segments allocated according to bits in a transmitter; the first signal is signal A loaded onto the segment or segment combination allocated to the j-th bit (j) [n];

[0240] The second signal is The Are respectively input into the second electro-optical converter to generate the modulated local signal

[0241] In some embodiments, the analog characteristic is a frequency-dependent difference between different segments or different combinations of segments allocated according to bits in a transmitter; the first signal is signal A loaded onto the segment or segment combination allocated to the j-th bit (j) [n];

[0242] The second signal is The Are respectively input into the second electro-optical converter to generate the modulated local signal q is an integer, Y is an empirical value selected according to the analog characteristic of the transmitter to be measured, and τ is a unit time delay less than T;

[0243] Or,

[0244] When (q - 1)τ = mT + δ, 0 ≤ δ < T, the second signal is The are respectively input into the second electro-optical converter to generate the modulated local signal

[0245] In some embodiments, the analog characteristic is the difference between the overall different polarization states in a dual-polarization transmitter or between different segments (segments) allocated according to bits within different polarization states or between different segment combinations;

[0246] H and V respectively represent the H polarization state and the V polarization state of the dual-polarization transmitter, and the second signals of the H path and the V path of the dual-polarization transmitter are respectively and

[0247] In some embodiments, the analog characteristic is the analog characteristic of the first electro-optical converter under a specific symbol or a specific symbol sequence; the first signal is represented as A[n], and the second signal B 10 [n] is a constant when corresponding to the specific symbol, or the second signal B 11 [n] is a constant when corresponding to the central symbol of the specific symbol sequence, and the modulated local signal is a pulse signal.

[0248] In some embodiments, the analog characteristic is the static and dynamic analog characteristics of each segment in a transmitter with a cascaded structure of multiple segment modulators; the first signal of the segment to be measured is A (s) [n], and the first signal of the segment not to be measured is A (w) [n]=0, w≠s;

[0249] The second signal is The are respectively input into the second electro-optical converter to generate the modulated local signal q is an integer, and τ is a unit time delay less than T;

[0250] Or,

[0251] When (q - 1)τ = mT + δ, 0 ≤ δ < T, the second signal is The are respectively input into the second electro-optical converter to generate the modulated local signal

[0252] In some embodiments, the device further includes:

[0253] A quantization unit quantizes the first signal or the second signal using at least one bit, and inputs the quantized signal into the second electro-optical converter to obtain the modulated local signal.

[0254] In some embodiments, the first electro-optical converter is a transmitter, or a partial modulation unit of a transmitter, or a directly modulated laser.

[0255] In some embodiments, the second electro-optical converter outputs a finite number of states.

[0256] In some embodiments, the first electro-optical converter and the second electro-optical converter are connected in parallel; the first electro-optical converter generates the optical signal to be measured based on the optical carrier and the first signal, and the second electro-optical converter generates the modulated local signal based on the optical carrier and the second signal;

[0257] The optical signal to be measured and the modulated local signal are respectively input into an optoelectronic multiplier to obtain a product electrical signal; and the product electrical signal is electrically averaged to generate the at least one correlation quantity.

[0258] In some embodiments, the first electro-optical converter and the second electro-optical converter are connected in series; the first electro-optical converter generates the optical signal to be measured based on the optical carrier and the first signal, and the second electro-optical converter generates the modulated local signal based on the optical signal to be measured and the second signal;

[0259] The modulated local signal is input to an optical-to-electrical converter to obtain an electrical signal; and the electrical signal is electrically averaged to generate the at least one correlation quantity.

[0260] It is worth noting that the above description only describes the components or modules related to the present application, but the present application is not limited thereto. The optical transmitter analog characteristic monitoring device 1800 may also include other components or modules. For details of these components or modules, please refer to the relevant art.

[0261] To keep it simple, Figure 18 The connection relationships and signal paths between various components or modules are shown for illustrative purposes only. However, those skilled in the art will appreciate that various related technologies, such as bus connections, can be employed. The aforementioned components or modules can be implemented using hardware such as processors and memory; this is not a limitation of the present invention.

[0262] The above embodiments are merely exemplary of the present invention, but the present invention is not limited thereto. Appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0263] As can be seen from the above embodiments, the hardware cost required to extract the analog characteristic information of the optical transmitter by using the correlation between the optical signal to be measured and the modulated local signal is much lower than that of a conventional broadband receiver, and since complex DSP processing is not required, the power consumption is greatly reduced.

[0264] Embodiments of the third aspect

[0265] This embodiment of the present application provides an electronic device including an apparatus 1800 for monitoring analog characteristics of an optical transmitter as described in the embodiment of the second aspect, the contents of which are incorporated herein. The electronic device may be, for example, a computer, a server, a workstation, a laptop computer, a smartphone, etc., but this embodiment of the present application is not limited thereto.

[0266] Figure 19 Schematic diagram of an electronic device according to an embodiment of the present application. Figure 19 As shown, electronic device 1900 may include: a processor (e.g., a central processing unit (CPU)) 1910 and a memory 1920; the memory 1920 is coupled to the CPU 1910. The memory 1920 may store various data; in addition, it may store an information processing program 1921, and the program 1921 may be executed under the control of the processor 1910.

[0267] In some embodiments, the functions of the optical transmitter analog characteristic monitoring apparatus 1800 are integrated into the processor 1910. The processor 1910 is configured to implement the optical transmitter analog characteristic monitoring method as described in the embodiment of the first aspect.

[0268] In some embodiments, the monitoring device 1800 for the analog characteristics of the optical transmitter is configured separately from the processor 1910. For example, the monitoring device 1800 for the analog characteristics of the optical transmitter can be configured as a chip connected to the processor 1910, and the functions of the monitoring device 1800 for the analog characteristics of the optical transmitter are realized through the control of the processor 1910.

[0269] For example, processor 1910 is configured to perform the following control: input a first signal into a first electro-optical converter to obtain an optical signal to be measured; input a second signal into a second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined based on the first signal and the analog characteristics to be monitored of the first electro-optical converter; correlate the optical signal to be measured and the modulated local signal to obtain at least one correlation quantity; and estimate the analog characteristics of the first electro-optical converter based on the correlation quantity.

[0270] In addition, if Figure 19As shown, the electronic device 1900 may further include: an input / output (I / O) device 1930 and a display 1940, etc.; wherein, the functions of the above components are similar to those of the prior art and are not described here in detail. It is worth noting that the electronic device 1900 does not necessarily have to include Figure 19 In addition, the electronic device 1900 may also include Figure 19 For components not shown, reference may be made to related art.

[0271] An embodiment of the present application further provides an optical transmitter, comprising a first electro-optical converter and a second electro-optical converter, characterized in that a first signal is input into the first electro-optical converter to obtain an optical signal to be measured; a second signal is input into the second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined based on the first signal and an analog characteristic to be monitored of the first electro-optical converter;

[0272] The optical transmitter further includes a monitoring device for performing correlation processing on the optical signal to be measured and the modulated local signal to obtain at least one correlation quantity; and estimating an analog characteristic of the first electro-optical converter according to the correlation quantity.

[0273] An embodiment of the present application also provides a computer-readable program, wherein when the program is executed in an electronic device, the program enables the computer to execute the method for monitoring the analog characteristics of an optical transmitter as described in the embodiment of the first aspect in the electronic device.

[0274] An embodiment of the present application also provides a storage medium storing a computer-readable program, wherein the computer-readable program enables a computer to execute the method for monitoring the analog characteristics of an optical transmitter as described in the embodiment of the first aspect in an electronic device.

[0275] The above devices and methods of the present application can be implemented by hardware or by a combination of hardware and software. The present application relates to such a computer-readable program that, when executed by a logic component, enables the logic component to implement the devices or components described above, or enables the logic component to implement the various methods or steps described above. The present application also relates to a storage medium for storing the above program, such as a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, etc.

[0276] The method / device described in conjunction with the embodiments of the present application can be directly embodied as hardware, a software module executed by a processor, or a combination of the two. For example, one or more of the functional block diagrams shown in the figure and / or one or more combinations of functional block diagrams can correspond to various software modules of the computer program flow or to various hardware modules. These software modules can respectively correspond to the various steps shown in the figure. These hardware modules can be implemented by solidifying these software modules, for example, using a field programmable gate array (FPGA).

[0277] The software module may be located in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. A storage medium may be coupled to a processor so that the processor can read information from the storage medium and write information to the storage medium; or the storage medium may be an integral part of the processor. The processor and the storage medium may be located in an ASIC. The software module may be stored in the memory of the mobile terminal or in a memory card that can be inserted into the mobile terminal. For example, if the device (such as a mobile terminal) uses a large-capacity MEGA-SIM card or a large-capacity flash memory device, the software module may be stored in the MEGA-SIM card or the large-capacity flash memory device.

[0278] One or more of the functional blocks and / or one or more combinations of functional blocks described in the accompanying drawings may be implemented as a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or any appropriate combination thereof for performing the functions described in this application. One or more of the functional blocks and / or one or more combinations of functional blocks described in the accompanying drawings may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in communication with a DSP, or any other such configuration.

[0279] The present application has been described above with reference to specific embodiments. However, those skilled in the art should understand that these descriptions are merely illustrative and are not intended to limit the scope of protection of the present application. Those skilled in the art may make various modifications and variations to the present application based on the principles of the present application, and such modifications and variations are also within the scope of the present application.

Claims

1. A monitoring device for analog characteristics of an optical transmitter, characterized in that: The device comprises: a first input unit, which inputs the first signal into the first electro-optical converter to obtain a light signal to be measured; a second input unit, which inputs a second signal into a second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined according to the first signal and an analog characteristic to be monitored by the first electro-optical converter; a correlation unit configured to perform correlation processing on the optical signal to be measured and the modulated local signal to obtain at least one correlation quantity; An estimating unit estimates an analog characteristic of the first electro-optical converter according to the correlation amount.

2. The device according to claim 1, wherein The correlation quantity represents a value of an impulse response of the cascade of the first electro-optical converter and the second electro-optical converter at a first moment, where the first moment depends on a relative delay between the first signal and the second signal.

3. The device according to claim 1, wherein When at least two superimposed signals are sent to the transmitter, each signal is monitored at least once to obtain at least two correlation quantities, and the analog characteristics of the first electro-optical converter are estimated based on the at least two correlation quantities.

4. The device according to claim 1, wherein The simulated characteristic is the frequency-independent IQ imbalance of the coherent transmitter; the first signal is A[n]=A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter respectively; The second signal is and described and are successively input to the second electro-optical converter to generate a modulated local signal and or, The second signal is and described and are successively input to the second electro-optical converter to generate the modulated local signal and 5. The device according to claim 1, wherein The analog characteristic is the IQ deviation of the coherent transmitter; the first signal is A[n]=A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter respectively; The second signal is and m=1,2,…,M, and are successively input to the second electro-optical converter to generate a modulated local signal 6. The device according to claim 1, wherein The simulated characteristic is the frequency-dependent IQ imbalance of the coherent transmitter; the first signal is A[n]=A I [n]+jA Q [n], where A I [n] and A Q [n] represents the signals loaded into the I branch and Q branch of the coherent transmitter respectively; The second signal is described and are successively input to the second electro-optical converter to generate a modulated local signal q is an integer, Y is an empirical value selected based on the simulated characteristics of the transmitter to be tested, and τ is a unit delay less than T; or, When (q - 1)τ = mT + δ, where 0 ≤ δ < T, the second signal is the and are successively input into the second electro-optical converter to generate a modulated local signal 7. The device according to claim 1, wherein The analog characteristic is the frequency-independent difference between different segments or different segment combinations according to bit allocation in the transmitter; the first signal is the signal A loaded on the segment or segment combination allocated by the jth bit. (j) [n]; The second signal is described are successively input to the second electro-optical converter to generate the modulated local signal or, The second signal is described are successively input to the second electro-optical converter to generate the modulated local signal 8. The device according to claim 1, wherein The analog characteristic is the deviation difference between different segments or different segment combinations according to bit allocation in the transmitter; the first signal is the signal A loaded on the segment or segment combination allocated by the jth bit. (j) [n]; The second signal is described are successively input to the second electro-optical converter to generate the modulated local signal 9. The device according to claim 1, wherein The analog characteristic is the frequency-related difference between different segments or different segment combinations according to bit allocation in the transmitter; the first signal is the signal A loaded on the segment or segment combination allocated by the jth bit. (j) [n]; The second signal is described are successively input to the second electro-optical converter to generate the modulated local signal q is an integer, Y is an empirical value selected based on the simulated characteristics of the transmitter to be tested, and τ is a unit delay less than T; or, When (q - 1)τ = mT+δ, 0 ≤ δ < T, the second signal is the successively input into the second electro - optical converter respectively to generate the modulated local signal 10. The device according to claim 1, wherein The simulation characteristic is the difference between different polarization states as a whole or between different segments or different combinations of segments in different polarization states according to bit allocation; H and V represent the H polarization state and V polarization state of the dual-bias transmitter, respectively. The second signals of the H path and V path of the dual-bias transmitter are and 11. The device according to claim 1, wherein The analog characteristic is the analog characteristic of the first electro-optical converter under a specific symbol or a specific symbol sequence; the first signal is represented by A[n], and the second signal B 10 [n] is a constant when corresponding to the specific symbol, or the second signal B 11 [n] is a constant when corresponding to the central symbol of the specific symbol sequence, and the modulated local signal is a pulse signal.

12. The device according to claim 1, wherein The analog characteristics are the static and dynamic analog characteristics of each segment in a transmitter with a cascade structure of multiple segment modulators; the first signal of the segment to be measured is A (s) [n], the first signal of the non-test segment is A (w) [n]=0,w≠s; The second signal is described are successively input to the second electro-optical converter to generate the modulated local signal q is an integer, τ is a unit delay less than T; or, When (q - 1)τ = mT + δ, where 0 ≤ δ < T, the second signal is the successively input into the second electro-optical converter to generate the modulated local signal 13. The device according to claim 1, wherein The device further comprises: A quantization unit quantizes the first signal or the second signal using at least one bit, and inputs the quantized signal into the second electro-optical converter to obtain the modulated local signal.

14. The device according to claim 1, wherein The first electro-optical converter is the transmitter itself, or a partial modulation unit of the transmitter, or a directly modulated laser; The second electro-optical converter outputs a finite number of states.

15. The device according to claim 1, wherein The first electro-optical converter and the second electro-optical converter are connected in parallel; the first electro-optical converter generates the optical signal to be measured based on the optical carrier and the first signal, and the second electro-optical converter generates the modulated local signal based on the optical carrier and the second signal; The optical signal to be measured and the modulated local signal are respectively input into an optoelectronic multiplier to obtain a product electrical signal; And the product electrical signal is electrically averaged to generate the at least one correlation quantity.

16. The device according to claim 1, wherein The first electro-optical converter and the second electro-optical converter are connected in series; the first electro-optical converter generates the optical signal to be measured based on the optical carrier and the first signal, and the second electro-optical converter generates the modulated local signal based on the optical signal to be measured and the second signal; The modulated local signal is input to an optical-to-electrical converter to obtain an electrical signal; and the electrical signal is electrically averaged to generate the at least one correlation quantity.

17. A method for monitoring analog characteristics of an optical transmitter, characterized in that: The method comprises: Inputting the first signal into the first electro-optical converter to obtain an optical signal to be measured; Inputting a second signal into a second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined based on the first signal and an analog characteristic to be monitored by the first electro-optical converter; Performing correlation processing on the optical signal to be measured and the modulated local signal to obtain at least one correlation quantity; An analog characteristic of the first electro-optical converter is estimated based on the correlation quantity.

18. An optical transmitter comprising a first electro-optical converter and a second electro-optical converter, characterized in that: A first signal is input into the first electro-optical converter to obtain an optical signal to be measured; a second signal is input into the second electro-optical converter to obtain a modulated local signal; wherein the second signal is determined based on the first signal and the analog characteristic to be monitored of the first electro-optical converter; The optical transmitter further includes a monitoring device for performing correlation processing on the optical signal to be measured and the modulated local signal to obtain at least one correlation quantity; and estimating an analog characteristic of the first electro-optical converter according to the correlation quantity.

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