Test method, tester and test system of optical transmitter

Abstract

The embodiment of the invention provides a test method, a tester and a test system of an optical transmitter, which are applied to the technical field of optical communication test. The testing method comprises the steps that an eye pattern is obtained, the eye pattern is used for describing the situation that the voltage amplitude of an electric signal changes along with time within the multi-order level range, the electric signal is obtained by converting an optical signal received by an optical fiber interface, the optical fiber interface is connected with an optical transmitter through an optical fiber, and the optical signal is a multi-order modulation signal. The eye pattern is sampled to obtain a plurality of sampling points, the voltage amplitudes of the electric signals of the sampling points are counted to obtain amplitude distribution information, and the amplitude distribution information is used for describing distribution information of the voltage amplitudes of the electric signals of the sampling points in a multi-order level range. And outputting the TDEC value of the optical transmitter and / or the OMA value of the transmitter according to the amplitude distribution information. According to the embodiment of the invention, the calculation accuracy of the TDEC value and the OMA value of the optical transmitter is improved.

Description

Technical Field

[0001] The present application relates to the field of optical communication testing technology, and in particular to a testing method, a testing instrument and a testing system for an optical transmitter. Background Art

[0002] In the field of communication technology, it is necessary to regulate communication production, communication construction and communication activities based on certain communication technology standards to ensure that all communications can be carried out in an orderly and efficient manner. Communication technology standards set relevant standards for all aspects of communication, such as product standards. Product standards are unified regulations for product quality specifications and performance indicators based on communication products and their contents. For example, for optical transmitters, some communication technology standards give transmitter and dispersion eye closure (TDEC) values ​​and / or optical modulation amplitude (OMA) values ​​as performance indicator parameters to measure whether product performance meets certain standards. Therefore, in scenarios such as production, manufacturing, maintenance or testing of optical transmitters, it is necessary to test the TDEC value and OMA value of the optical transmitter.

[0003] A test method for an optical transmitter is as follows: converting an optical signal emitted by the optical transmitter into an electrical signal, and obtaining an eye diagram according to the electrical signal, wherein the eye diagram is used to describe the variation of the voltage amplitude of the electrical signal over time within a multi-level range. Based on a tester, the voltage amplitude of the eye diagram is calculated and processed using a fixed calculation formula, thereby obtaining a test result of the TDEC value and / or OMA value of the optical transmitter. However, in actual applications, there are influencing factors in the transmission and processing of optical and electrical signals, which will cause the voltage amplitude of the actual eye diagram to deviate greatly from the ideal value. In this way of calculating and processing the voltage amplitude of the eye diagram based on a fixed calculation formula, calculation errors will inevitably exist in both the intermediate variables obtained by processing and the final test results. This calculation error will greatly affect the accuracy of the test results. Summary of the invention

[0004] The embodiments of the present application provide a test method, a tester and a test system for an optical transmitter, which improve the test accuracy of the performance indicators of the optical transmitter.

[0005] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0006] In a first aspect, a test method for an optical transmitter is provided, which can be used to test and calculate the TDEC value of the optical transmitter. The method includes: obtaining an eye diagram, the eye diagram is used to describe the change of the voltage amplitude of an electrical signal over time within a multi-level range, the electrical signal is converted from an optical signal received by an optical fiber interface, the optical fiber interface is connected to the optical transmitter through an optical fiber, and the optical signal is a multi-level modulated signal. The eye diagram is sampled to obtain multiple sampling points, and the voltage amplitude of the electrical signal at the multiple sampling points is statistically analyzed to obtain amplitude distribution information, and the amplitude distribution information is used to describe the distribution of the voltage amplitude of the electrical signal at the multiple sampling points within a multi-level range. A first test result is output according to the amplitude distribution information, and the first test result is used to indicate the TDEC value of the optical transmitter.

[0007] In an embodiment of the present application, the distribution of voltage amplitudes of multiple sampling points in the eye diagram within a multi-level range is obtained based on a statistical method. Since the voltage amplitude changes of multiple sampling points are obtained based on actual optical devices and optical signals after optical fiber transmission, the actual statistical results will also change with the actual transmission of the optical signal. The amplitude distribution information obtained by statistics includes the change of the voltage amplitude of each level of the electrical signal under actual transmission over time. The calculation of the TDEC value or the OMA value based on the amplitude distribution information can take into account the distortion of the optical signal caused by the transmission, thereby increasing the calculation accuracy of the TDEC value and the OMA value.

[0008] In some possible implementations, the outputting of the first test result according to the amplitude distribution information includes: obtaining multiple voltage thresholds according to the amplitude distribution information, the multiple voltage thresholds are used to define the level intervals of multiple groups of adjacent levels within the multi-level range, and each of the multiple voltage thresholds is used to define the level interval of one group of adjacent levels in the multiple groups of adjacent levels. Outputting the first test result according to the multiple voltage thresholds. In the embodiment of the present application, multiple voltage thresholds are obtained based on the amplitude distribution information. Multiple voltage thresholds are used to define the level intervals of multiple groups of adjacent levels within the multi-level range, and each of the multiple voltage thresholds is used to define the level interval of one group of adjacent levels in the multiple groups of adjacent levels. Because the amplitude distribution information is obtained based on actual transmission statistics, the voltage amplitude of each level in the amplitude distribution information is affected by the distortion of the transmission. The voltage threshold corresponding to each group of adjacent levels is calculated based on the amplitude distribution information to obtain multiple voltage thresholds. In this way, the voltage thresholds used to define the level interval are all obtained based on the voltage amplitude of the corresponding level in the amplitude distribution information. At this time, the calculation of multiple voltage thresholds also takes into account the influence of the distortion of the actual transmission, and the calculation accuracy is higher. In this case, the calculation accuracy of the first test result obtained based on multiple voltage thresholds will also be higher.

[0009] In some examples, the above-mentioned obtaining multiple voltage thresholds according to the amplitude distribution information includes: for a first group of adjacent two-step levels in multiple groups of adjacent levels, performing the following operations to obtain a voltage threshold for defining a level interval of the first group of adjacent levels: obtaining a first amplitude and a second amplitude according to the voltage amplitude of the electrical signal of multiple sampling points, wherein the first amplitude is the mode amplitude among multiple amplitudes corresponding to the first level in the amplitude distribution information, the second amplitude is the mode amplitude among multiple amplitudes corresponding to the second level in the amplitude distribution information, and the first level and the second level are two levels in the first group of adjacent levels. According to the first amplitude and the second amplitude, a voltage threshold for defining the first level and the second level is obtained. In the embodiment of the present application, the first amplitude and the second amplitude are the mode amplitudes among multiple amplitudes in the corresponding levels. In the amplitude distribution information, the mode amplitude corresponding to each level changes with the change of the distortion effect of the actual transmission. The value of the mode amplitude can be statistically characterized by the value characteristics of the sampling interval. Therefore, by calculating the voltage threshold based on the mode amplitude of adjacent levels in the amplitude distribution information, a voltage threshold closer to the actual situation can be obtained on the basis of considering the influence of distortion in actual transmission, so as to improve the calculation accuracy of multiple voltage thresholds.

[0010] Exemplarily, the voltage threshold for defining the first level and the second level is obtained based on the first amplitude and the second amplitude, including: a first amplitude set obtained by taking the maximum value of the first amplitude as the sampling center and the first amplitude difference as the width of the sampling area in the amplitude distribution information. A second amplitude set obtained by taking the maximum value of the second amplitude as the sampling center and the second amplitude difference as the width of the sampling area in the amplitude distribution information. The voltage threshold for defining the first level and the second level is obtained based on the average amplitude of the first amplitude set and the second amplitude set. In the embodiment of the present application, in the amplitude distribution information, the changes in the voltage amplitude within a certain area centered on the mode amplitude are all affected by actual transmission, and can represent the value characteristics of the level within the sampling area to a certain extent. Therefore, the voltage amplitude is sampled based on the mode amplitude with a certain amplitude difference to obtain an amplitude set. Based on the mode amplitude in the amplitude set and a certain amplitude value distributed around it, a more accurate voltage threshold can be obtained.

[0011] In a possible implementation, the output of the first test result according to the multiple voltage thresholds includes: obtaining the voltage amplitude change period distribution of the electrical signal of the eye diagram according to the time information of the electrical signal of the multiple sampling points. According to the voltage amplitude change period distribution, regional sampling is performed on the eye diagram to obtain a regional histogram, and the regional histogram includes some sampling points among the multiple sampling points, and the time difference between the moment of the electrical signal of the partial sampling points and the midpoint of the period of the corresponding voltage amplitude change period belongs to the first duration. According to the multiple voltage thresholds and the regional histogram, the first test result is output. In the embodiment of the present application, the voltage amplitude in the amplitude distribution information is the voltage amplitude of the multiple sampling points of the electrical signal actually transmitted. These sampling points are distributed in different period moments on the eye diagram and have different voltage amplitudes. Therefore, the voltage amplitude change period distribution of the electrical signal of the eye diagram can also be calculated based on the amplitude distribution information. The calculated voltage amplitude change period distribution is more consistent with the voltage amplitude change period distribution of the electrical signal of the actual eye diagram. According to the obtained period distribution, sampling is performed at the period distribution points specified in the standard to obtain a regional histogram. Then, the first test result is calculated based on multiple voltage thresholds and the regional histogram. Because the calculated period distribution is closer to the actual period distribution, the sampling range of the regional histogram obtained based on the calculated period distribution is also closer to the ideal sampling range. The first test result obtained based on the regional histogram and multiple voltage thresholds is also closer to the actual test result of the optical transmitter.

[0012] In a possible implementation, the above-mentioned obtaining the voltage amplitude change period distribution of the electrical signal of the eye diagram according to the time information of the electrical signal of the plurality of sampling points includes: dividing the plurality of sampling points into sampling points at a plurality of moments according to the time information of the electrical signal of the plurality of sampling points. Obtaining the amplitude variance of the sampling points at the first moment according to the distribution information of the voltage amplitude of the electrical signal of the plurality of sampling points at the first moment among the plurality of moments within the multi-order level range, and so on to obtain the amplitude variance at each moment among the plurality of moments. According to the amplitude variance at each moment, the maximum value of the amplitude variance of the electrical signal of the eye diagram in each amplitude change period is obtained. According to the maximum value of the amplitude variance of the electrical signal of the eye diagram in each amplitude change period, the period distribution of the electrical signal of the eye diagram in each amplitude change period is obtained, wherein the period distribution includes the midpoint of the period, the starting point of the period and the end point of the period. In the embodiment of the present application, the voltage amplitude in the amplitude distribution information is the voltage amplitude of the plurality of sampling points of the electrical signal actually transmitted. These sampling points are distributed in different period moments on the eye diagram and have different voltage amplitudes. The amplitude variance of the plurality of sampling points at each period moment can be calculated. The moment when the amplitude variance has a maximum value in a cycle is the midpoint of the cycle. The corresponding cycle start and end points can be confirmed by the midpoints of adjacent cycles. Compared with the method of finding the amplitude crossing point in the eye diagram, the amplitude variance method can confirm the cycle distribution more quickly and accurately.

[0013] In a possible implementation, the absolute value of the first duration is 0.1 amplitude variation cycle length. In the embodiment of the present application, the maximum sampleable area, i.e., 0.4-0.6 cycle point, can be obtained by taking the midpoint of the cycle as the midpoint of the sampling area and taking the 0.1 amplitude variation cycle length before and after as the sampling radius.

[0014] Exemplarily, the above-mentioned regional sampling based on the voltage amplitude change period distribution in the eye diagram to obtain the regional histogram includes: taking the 0.45 amplitude change period point as the regional center to sample in the first area of ​​the first amplitude change period of the eye diagram to obtain the first regional histogram. Taking the 0.55 amplitude change period point as the regional center to sample in the second area of ​​the first amplitude change period to obtain the second regional histogram. In the embodiment of the present application, according to the provisions of some communication standards, within the range of 0.4-0.6 period points, sampling can be performed with the 0.45 amplitude change period point as the regional center to obtain the first regional histogram; sampling can be performed with the 0.55 amplitude change period point as the regional center to obtain the second regional histogram. Among them, according to different standards, the provisions for the period length of the first regional histogram and the second regional histogram are also different. For example, the first regional histogram can be obtained by sampling with the 0.45 period point as the regional center and the 0.04 period length as the regional width. The second region histogram can be obtained by sampling with the 0.55 period point as the region center and the 0.04 period length as the region width.

[0015] Exemplarily, the optical signal is a 4th-order modulation signal, and the TDEC value is a TDECQ value. In an embodiment of the present application, depending on the order of the multi-order modulation, a name suffix representing the corresponding order may be added to the name of the TDEC value. For example, for 4th-order pulse amplitude modulation (four-level pulse amplitude modulation, PAM4), its TDEC value may be called transmitter and dispersion eye closure quaternary (transmitter and dispersion eye closure for PAM4, TDECQ). Therefore, the TDEC value under four levels (quaternary) may be called the TDECQ value. Similarly, in other multi-order modulations (such as 2nd order, 6th order, 8th order, etc.), a name suffix representing the corresponding order may also be added.

[0016] In a possible implementation, the method can also test and calculate the OMA value of the optical transmitter while testing and calculating the TDEC value of the optical transmitter. At this time, the method also includes: outputting a second test result according to the amplitude distribution information, and the second test result is used to indicate the OMA value of the optical transmitter. In the embodiment of the present application, because many communication technology standards use TDEC values ​​and OMA values ​​together as indicator parameters for measuring the performance of optical transmitters. Therefore, the OMA value can also be tested and calculated while testing and calculating the TDEC value. The OMA value is calculated based on the amplitude distribution information, because the amplitude distribution information is related to the distortion effect of the actual transmission, the obtained OMA value is closer to the performance measurement of the optical transmitter in actual application.

[0017] In a possible implementation, the above-mentioned output of the second test result according to the amplitude distribution information includes: obtaining a third amplitude and a fourth amplitude according to the amplitude distribution information, the third amplitude being the mode amplitude among multiple amplitudes of the highest level in the multi-order level, and the fourth amplitude being the mode amplitude among multiple amplitudes of the lowest level in the multi-order level. Output the second test result according to the third amplitude and the fourth amplitude. In the embodiment of the present application, the OMA value is used to indicate the difference in optical power amplitude between the highest level and the lowest level. And the mode amplitude of the highest level and the lowest level obtained according to the amplitude distribution information. Affected by the distortion in the actual transmission of the optical signal, the highest level and the lowest level will also change. And the mode amplitude changes with the change of the highest level and the lowest level. And the mode amplitude can characterize the value characteristics of the corresponding level area. Therefore, the second test result obtained based on the mode amplitude obtained from the highest level and the lowest level is also closer to the actual transmission performance test of the optical transmitter.

[0018] In a possible implementation, the second test result is outputted based on the third amplitude and the fourth amplitude, including: a third amplitude set obtained by taking the maximum value of the third amplitude as the sampling center and the third amplitude difference as the width of the sampling area in the amplitude distribution information. A fourth amplitude set obtained by taking the maximum value of the fourth amplitude as the sampling center and the fourth amplitude difference as the width of the sampling area in the amplitude distribution information. The second test result is outputted based on the difference in the average amplitude between the third amplitude set and the fourth amplitude set. In the embodiment of the present application, in the amplitude distribution information, the changes in the voltage amplitude within a certain area centered on the mode amplitude are all affected by the actual transmission, and can represent the value characteristics of the level within the sampling area to a certain extent. Therefore, the voltage amplitude is sampled based on the mode amplitude with a certain amplitude difference to obtain an amplitude set. Based on the mode amplitude in the amplitude set and certain amplitude values ​​distributed around it, a more accurate OMA value can be obtained.

[0019] In the second aspect, the embodiment of the present application also provides a test method for an optical transmitter, which can be used to test and calculate the OMA value of the optical transmitter. The method includes: obtaining an eye diagram, the eye diagram is used to describe the change of the amplitude of the electrical signal over time, the electrical signal is a signal including multi-order levels obtained by converting the optical signal received by the optical fiber interface, the optical fiber interface is connected to the optical transmitter through an optical fiber, and the optical signal is a multi-order modulated signal. The eye diagram is sampled to obtain multiple sampling points, and the voltage amplitude of the electrical signal at the multiple sampling points is counted to obtain amplitude distribution information, and the amplitude distribution information is used to describe the distribution of the voltage amplitude of the electrical signal at the multiple sampling points within the multi-order level range. Output a second test result according to the amplitude distribution information; the second test result is used to indicate the OMA value of the optical transmitter.

[0020] In a possible implementation, outputting the second test result according to the amplitude distribution information includes: obtaining a third amplitude and a fourth amplitude according to the amplitude distribution information, wherein the third amplitude is a mode amplitude among multiple amplitudes corresponding to the highest level in the amplitude distribution information, and the fourth amplitude is a mode amplitude among multiple amplitudes corresponding to the lowest level in the amplitude distribution information. Outputting the second test result according to the third amplitude and the fourth amplitude.

[0021] In a possible implementation, the outputting of the second test result according to the third amplitude and the fourth amplitude includes: a third amplitude set obtained by taking the third amplitude as a sampling center and the third amplitude difference as a sampling area width in the amplitude distribution information; a fourth amplitude set obtained by taking the fourth amplitude as a sampling center and the fourth amplitude difference as a sampling area width in the amplitude distribution information; and outputting the second test result according to the difference between the average amplitudes of the third amplitude set and the fourth amplitude set.

[0022] In a third aspect, an embodiment of the present application further provides a tester based on which the TDEC value of an optical transmitter is tested and calculated. At this time, the tester is used to: obtain an eye diagram, which is used to describe the change of the voltage amplitude of an electrical signal over time within a multi-order level range. The electrical signal is converted from an optical signal received by an optical fiber interface. The optical fiber interface is connected to the optical transmitter through an optical fiber, and the optical signal is a multi-order modulated signal. The eye diagram is sampled to obtain multiple sampling points, and the voltage amplitudes of the electrical signals at the multiple sampling points are statistically analyzed to obtain amplitude distribution information. The amplitude distribution information is used to describe the distribution of the voltage amplitudes of the electrical signals at the multiple sampling points within a multi-order level range. A first test result is output according to the amplitude distribution information, and the first test result is used to indicate the TDEC value of the optical transmitter.

[0023] In a possible implementation manner, the optical signal is a 4th-order modulation signal, and the TDEC value is a TDECQ value.

[0024] In a possible implementation, in the process of testing and calculating the TDEC value of the optical transmitter based on the tester, the OMA value of the optical transmitter can also be tested and calculated based on the tester. At this time, the tester is also used to: output a second test result according to the amplitude distribution information, and the second test result is used to indicate the OMA value of the optical transmitter.

[0025] In some examples, the eye diagram is obtained as described above, including: receiving an electrical signal, and performing signal processing on the electrical signal to obtain the eye diagram. In an embodiment of the present application, the tester may be an instrument integrating an oscilloscope function and a test function. In this case, the tester may perform signal processing on the electrical signal based on the oscilloscope function to obtain the eye diagram. Then, the tester calculates the first test result and / or the second test result based on the test function.

[0026] In some examples, the eye diagram is obtained as described above, including: inputting the eye diagram. In an embodiment of the present application, the tester can obtain the eye diagram generated by other instruments with integrated oscilloscope function offline. Then, the tester calculates the first test result and / or the second test result based on the test function.

[0027] In a fourth aspect, an embodiment of the present application further provides a tester based on which the OMA value of an optical transmitter is tested and calculated. The tester is used to: obtain an eye diagram, which is used to describe the change of the voltage amplitude of an electrical signal over time within a multi-order level range. The electrical signal is converted from an optical signal received by an optical fiber interface. The optical fiber interface is connected to the optical transmitter through an optical fiber, and the optical signal is a multi-order modulated signal. The eye diagram is sampled to obtain multiple sampling points, and the voltage amplitudes of the electrical signals at the multiple sampling points are counted to obtain amplitude distribution information, which is used to describe the distribution of the voltage amplitudes of the electrical signals at the multiple sampling points within a multi-order level range. A second test result is output according to the amplitude distribution information; the second test result is used to indicate the OMA value of the optical transmitter.

[0028] In a possible implementation manner, the above-mentioned obtaining of the eye diagram includes: receiving an electrical signal, and performing signal processing on the electrical signal to obtain the eye diagram.

[0029] In a possible implementation manner, the step of obtaining the eye diagram includes: inputting the eye diagram.

[0030] In a fifth aspect, an embodiment of the present application further provides a test system, which includes an optical fiber interface, a photodetector, and a test circuit. Wherein: the optical fiber interface is used to: connect to an optical transmitter through an optical fiber, and receive an optical signal from the optical transmitter, and the optical signal is a multi-order modulated signal. The photodetector is used to: convert the optical signal into an electrical signal. The test circuit is used to: obtain an eye diagram based on the electrical signal; the eye diagram is used to describe the change of the voltage amplitude of the electrical signal over time within a multi-order level range. The eye diagram is sampled to obtain multiple sampling points, and the voltage amplitude of the electrical signal at the multiple sampling points is statistically analyzed to obtain amplitude distribution information, and the amplitude distribution information is used to describe the distribution of the voltage amplitude of the electrical signal at the multiple sampling points within a multi-order level range. Output the first test result and / or the second test result according to the amplitude distribution information, the first test result is used to indicate the TDEC value of the optical transmitter, and the second test result is used to indicate the OMA value of the optical transmitter.

[0031] In a possible implementation, the test circuit includes an oscilloscope and a first tester. The oscilloscope is used to generate an eye diagram according to the electrical signal. The first tester is used to obtain the eye diagram, sample the eye diagram to obtain multiple sampling points, and perform statistics on the voltage amplitudes of the electrical signals at the multiple sampling points to obtain amplitude distribution information. The first test result and / or the second test result are output according to the amplitude distribution information.

[0032] In a possible implementation, the test circuit includes a second tester. The second tester is used to: obtain an eye diagram according to the electrical signal, sample the eye diagram to obtain a plurality of sampling points, and perform statistics on the voltage amplitudes of the electrical signals at the plurality of sampling points to obtain amplitude distribution information, and output the first test result and / or the second test result according to the amplitude distribution information.

[0033] In a sixth aspect, an embodiment of the present application further provides a computer-readable storage medium, the computer-readable storage medium comprising instructions. When the instructions are executed on a processor, the processor executes the optical transmitter test method as described in the first aspect above, or executes the optical transmitter test method as described in the second aspect above.

[0034] Regarding the technical principles and beneficial effects of the second, third, fourth, fifth and sixth aspects, reference may be made to the relevant description of the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is an ideal eye diagram for 2nd order modulation;

[0036] Figure 2 This is an ideal eye diagram for 4th order modulation;

[0037] Figure 3 A structure of a test system provided in an embodiment of the present application Figure 1 ;

[0038] Figure 4 Another structure of a test system provided in an embodiment of the present application Figure 2 ;

[0039] Figure 5 Another structure of a test system provided in an embodiment of the present application Figure 3 ;

[0040] Figure 6 A flowchart of a first testing method provided in an embodiment of the present application;

[0041] Figure 7 An eye diagram actually obtained during a 4th-order modulation provided in an embodiment of the present application;

[0042] Figure 8 A flowchart of another first testing method provided in an embodiment of the present application;

[0043] Fig. 9 A process of a second testing method provided in an embodiment of the present application Figure 1 ;

[0044] Fig.10 A voltage amplitude distribution statistical diagram in the amplitude distribution information provided in an embodiment of the present application;

[0045] Fig.11 Another second test method provided in the present application embodiment Figure 2 ;

[0046] Fig.12 A process of another second testing method provided in the embodiment of the present application Figure 3 ;

[0047] Fig.13 A process of another second testing method provided in the embodiment of the present application Figure 4 ;

[0048] Fig.14 A distribution change diagram of variance at different times provided in an embodiment of the present application;

[0049] Fig.15 A schematic diagram of sampling positions of a regional histogram provided in an embodiment of the present application;

[0050] Fig.16 A rendering of a cumulative probability changing with a variable value provided in an embodiment of the present application;

[0051] Fig.17 A process of another second testing method provided in the embodiment of the present application Figure 5 . DETAILED DESCRIPTION

[0052] It should be noted that the terms "first", "second", etc. involved in the embodiments of the present application are only used to distinguish features of the same type and cannot be understood as indicating relative importance, quantity, order, etc.

[0053] The terms "exemplary" or "for example" and the like in the embodiments of the present application are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the related concepts in a specific way.

[0054] The terms "coupling" and "connection" involved in the embodiments of the present application should be understood in a broad sense. For example, they may refer to a direct physical connection, or an indirect connection achieved through electronic devices and / or photonic devices, such as a connection achieved through optical fibers, waveguides, optical filters, couplers, resistors, inductors, capacitors or other electronic devices and / or photonic devices.

[0055] First, some basic concepts involved in the embodiments of the present application are explained:

[0056] In the field of communication technology, it is necessary to regulate communication production, communication construction and communication activities based on certain communication technology standards to ensure that all communications can be carried out in an orderly and efficient manner. Communication technology standards set relevant standards for all aspects of communication, such as product standards. Product standards are unified regulations for product quality specifications and performance indicators based on communication products and their contents.

[0057] Eye diagram is used to describe the variation of the voltage amplitude of an electrical signal over time within a multi-level range. Electrical signals can be obtained by performing photoelectric conversion on optical signals, and eye diagrams are obtained by processing the electrical signals. These eye diagrams can intuitively reflect the signal quality of optical signals. When an oscilloscope is used to observe the eye diagram of an amplitude-modulated optical signal, when the scanning period of the visible signal window is an integer multiple of the signal period, the waveform obtained by the variation of the voltage amplitude of the electrical signal over time will form a stable graph similar to the shape of an eye. This shape is formed by the multi-level levels of the electrical signal and the rising and falling oscillating switching between its multi-level levels. Taking multi-level modulation as 2nd-order modulation as an example, 2nd-order modulation can also be called non-return-to-zero modulation (NRZ), such as Figure 1 The figure shows an ideal eye diagram under 2-order modulation. In an ideal eye diagram under 2-order modulation, there are two levels, 1 and -1. The voltage amplitude of the electrical signal oscillates between 1 and -1, and can form an eye-like shape within a voltage amplitude change cycle. Therefore, we call the waveform obtained by the voltage amplitude of the electrical signal changing over time within a multi-level range an eye diagram. Figure 1 It can be seen that the time points when the high and low levels on the left and right sides of the eye shape cross are the start and end points of a voltage amplitude change cycle, respectively, and the maximum opening of the eye shape is the midpoint of a voltage amplitude change cycle. When the signal noise in the optical signal is less, the signal quality of the optical signal is higher. At this time, in the corresponding eye diagram, the degree of opening of the eye shape will also be relatively high. When the signal noise in the optical signal is large, the signal quality of the optical signal is low. At this time, in the corresponding eye diagram, the degree of opening of the eye shape will also be relatively low. Even when the signal noise in the optical signal deteriorates to a certain extent, the eye shape will appear closed in the corresponding eye diagram. Figure 1 The eye diagram under 2-order modulation is used for explanation. In multi-order modulation with more than 2-order, the number of levels increases, and in one voltage amplitude change cycle, the multi-order levels with more than 2-order will form multiple eye-like shapes. Take 4-order modulation as an example. Figure 2 As shown, the change of the voltage amplitude of the electrical signal within the fourth-order level range over time can form three eye-like shapes within one voltage amplitude change cycle.

[0058] In the field of optical communication technology, service interaction can be achieved based on optical receivers and optical transmitters. Specifically, the optical transmitter modulates the data information onto the optical signal in multiple stages and transmits the optical signal to the optical receiver based on the optical fiber. In the field of optical communication technology, although optical communication products produced by different manufacturers have differences in packaging methods, transmission rates, transmission distances, and processing algorithms. However, in the communication technology standards of optical communication, there are still some product standards used to constrain certain specific performance indicators. Usually, engineers can process the optical signal to obtain the eye diagram of the optical signal. Based on the eye diagram, many specific performance indicators of optical devices can be detected. For example, the transmitter and dispersion eye closure (TDEC) value and the optical modulation amplitude (OMA) value.

[0059] The OMA value is the difference between the high-level optical power and the low-level optical power of a multi-order modulated optical signal, which can be used to reflect the performance of an optical module. The OMA value plays a great role and significance in evaluating the performance of optical modules under different modulation formats and rates, ensuring the reliability and stability of optical signal transmission, and detecting the compatibility between optical modules.

[0060] The TDEC value refers to the additional noise ratio of the transmitter under test when obtaining the same bit error rate compared to the ideal transmitter. Due to the nonlinearity of the optical transmitter and the link dispersion caused by optical fiber transmission, the optical signal will be distorted, making it impossible for the optical receiver to accurately detect different levels, resulting in the optical receiver's parsing error of the data information carried in the optical signal. The TDEC value is often used as a key indicator to measure the distortion of PAM4 optical signals caused by the nonlinearity of the optical transmitter and the dispersion in the optical fiber. As an important performance indicator for evaluating optical communication systems, the TDEC value is widely used in the testing and performance evaluation of optical modules, and plays an important role in the performance testing of optical modules and system deployment and maintenance. According to the different orders of multi-order modulation, the name suffix representing the corresponding order can be added to the name of the TDEC value. For example, for four-level pulse amplitude modulation (PAM4), its TDEC value can be called transmitter and dispersion eye closure for PAM4 (TDECQ). Therefore, the TDEC value under four levels (quaternary) can be called TDECQ value. Similarly, in other multi-order modulations (such as 2nd order, 6th order, 8th order, etc.), a name suffix representing the corresponding order may also be added.

[0061] In many standards (such as IEEE 802.3 and ITU-T G.694.1), OMA values ​​and / or TDEC values ​​have been used as performance indicators for determining the consistency of optical components. In the 802.3bs standard, OMA values ​​and TDEC values ​​(such as TDECQ values) have been used as test performance indicators for 200G optical transmitters and 400G optical transmitters. In the IEEE 802.3dj800G / 1.6T standard project, the determination scheme for TDEC values ​​has not yet been discussed, but it is also possible that TDEC values ​​will be used as relevant test performance indicators in this standard. Therefore, how to achieve fast and accurate measurement of OMA values ​​and / or TDEC values ​​of optical transmitters is beneficial to the application and development of optical communication technology.

[0062] In order to facilitate rapid and accurate testing of these performance indicators of optical communication products, an embodiment of the present application provides a testing system. Figure 3As shown, the test system 1000 includes an optical fiber interface 100, a photodetector 200 and a test circuit 300. The optical fiber interface 100 is used to connect to the optical transmitter 2000 through an optical fiber F and receive an optical signal from the optical transmitter 2000, where the optical signal is a multi-order modulated signal. The photodetector 200 is used to convert the optical signal into an electrical signal. The test circuit 300 is used to obtain an eye diagram based on the electrical signal, where the eye diagram is used to describe how the voltage amplitude of the electrical signal changes over time within a multi-order level range; and output a test result about the OMA value or the TDEC value based on the eye diagram.

[0063] In some possible implementations, such as Figure 4 As shown, the test circuit 300 includes an oscilloscope 310 and a first tester 320. The oscilloscope 310 is used to generate an eye diagram according to an electrical signal. The first tester 320 is used to obtain the eye diagram and output a test result about an OMA value or a TDEC value according to the eye diagram.

[0064] In some examples, such as Figure 4 The oscilloscope 310 in the illustrated embodiment can directly output the data related to the eye diagram to the first tester 320. The first tester 320 can obtain the eye diagram from the oscilloscope 310 in real time through the data interface.

[0065] In some examples, such as Figure 4 The oscilloscope 310 in the illustrated embodiment can store the data related to the eye diagram offline. The first tester 320 can read the data from the related memory to obtain the eye diagram.

[0066] In some possible implementations, such as Figure 5 As shown, the test circuit 300 includes a second tester 330. The second tester 330 is used to: obtain an eye diagram according to the electrical signal; and output a test result about an OMA value or a TDEC value according to the eye diagram. Exemplarily, the second tester 330 may be a test instrument that inherits an oscilloscope function and a data processing function.

[0067] In some possible implementations, such as Figure 3 , Figure 4 and Figure 5 As described above, the test system 1000 may further include an optical filter 400. The optical fiber interface 100 is coupled to the photodetector 200 via the optical filter 400. The optical filter 400 performs filtering processing on the optical signal, such as adjusting the bandwidth of the optical signal, to improve the quality of eye diagram generation.

[0068] In some possible implementations, such as Figure 3 , Figure 4 and Figure 5As described above, the test system 1000 may further include a clock recovery circuit 500. The clock recovery circuit 500 is coupled to the photodetector 200 and the test circuit 300 respectively. The clock recovery circuit 500 assists in the generation of the eye diagram, thereby improving the quality of signal processing.

[0069] In some possible implementations, based on the above Figure 4 The first tester 320 of the embodiment or based on the above Figure 5 The second tester 330 of the embodiment can execute the first test method based on a fixed calculation formula to obtain the OMA value and / or the TDEC value, such as Figure 6 As shown, the first test method includes the following steps S100A-S400A:

[0070] S100A. Obtain an OMA value based on a fixed calculation formula.

[0071] In some possible implementations, taking the multi-order modulation as 4-order modulation as an example, Figure 7 As shown in Figure 4 The first tester 320 shown or Figure 5 The eye diagram obtained by the second tester 330 is shown in FIG. In the eye diagram, the voltage peaks corresponding to the 7 consecutive highest levels and the voltage minimum values ​​corresponding to the 6 consecutive lowest levels are found. The highest average optical power is calculated based on the 7 voltage peaks, the lowest average optical power is calculated based on the 6 voltage minimum values, and the OMA value is obtained based on the difference between the highest average optical power and the lowest average optical power.

[0072] In the first test method, the Figure 7 The method described above can realize the calculation of OMA value. However, since the optical signal will be affected by the nonlinear characteristics of the optical device (such as the optical transmitter 2000) and the transmission dispersion of the optical fiber F during the transmission and processing, it is inevitable that there will be distortion on the optical signal. Figure 7 The eye diagram is shown in Figure 1. Figure 2There is a deviation between the eye diagrams of the 4th-order modulation in the ideal case shown. In this case, the distribution of different levels is uneven, and there may be large differences between the eye heights. When OMA is calculated by a fixed calculation method with the highest average optical power and the lowest average optical power, there will be a large deviation between the actual OMA value and the calculated OMA value. Therefore, the OMA value cannot accurately evaluate the signal quality. In addition, the code patterns of optical signals are different, and it is difficult or impossible to obtain continuous highest and lowest levels on some code patterns. For example, taking 4th-order modulation as an example, in the IEEE 802.3bs standard, the calculation of OMA values ​​requires the use of SSPRQ code pattern data or PRBS13Q code pattern data. However, the measured data may be a PRBS code pattern or other types of code patterns. Not all code patterns can obtain 7 consecutive levels of 3 (corresponding to the highest level of 4th-order modulation) and 6 consecutive levels of 0 (corresponding to the lowest level of 4th-order modulation). For example, some PRBS code patterns and other code patterns do not meet the requirements of continuous level 3 or level 0 after modulation, and the calculation of OMA values ​​cannot be realized.

[0073] Based on the OMA obtained in step S100A, in the first test method, the TDEC value can also be calculated in subsequent steps S200A to S400A based on the OMA value obtained in step S100A:

[0074] S200A: Determine and calculate multiple voltage thresholds and period distribution of voltage amplitude variation periods corresponding to the multi-step levels based on the OMA value.

[0075] In the first test method embodiment of the present application, Figure 7 As shown, in the eye diagram, a certain voltage threshold is required between two adjacent levels, and the level interval of the two adjacent levels is defined based on the voltage threshold. Based on multiple voltage thresholds, the amplitude interval of multiple levels can be divided on the eye diagram.

[0076] In the first test method, multiple thresholds may be calculated based on the OMA value obtained in step S100A. In this case, step S200A may include the following steps: Figure 8 The operations of steps S210A to S220A shown are:

[0077] S210A. Determine the average optical power of the optical signal and the periodic distribution of the voltage amplitude variation period of the electrical signal based on the eye diagram crossing number.

[0078] In some examples, it can be based on Figure 7 The average value of the number of crossings of the electrical signals of the multi-levels in the eye diagram shown determines the cycle start point and cycle end point of the voltage amplitude variation cycle.

[0079] In some examples, it can be based on Figure 7 The average optical power corresponding to the intersection of the multi-level electrical signals in the eye diagram shown in the figure determines the average optical power P of the optical signal. ave .

[0080] S220A, based on average optical power P ave and OMA values ​​are calculated for multiple voltage thresholds.

[0081] In some possible implementations, taking the multi-level as a four-level level as an example, three groups of adjacent two-level levels can be obtained: the first group of adjacent two-level levels is level 0 and level 1, the second group of adjacent two-level levels is level 1 and level 2, and the third group of adjacent two-level levels is level 2 and level 3. The level value here refers to the value that different levels can express in the data information. At this time, multiple thresholds can be calculated by the following fixed calculation formula:

[0082] P th1 =P ave -OMA outer / 3

[0083] P th2 =P ave

[0084] P th3 =P ave +OMA outer / 3

[0085] Where P th1 is the threshold voltage between the first two adjacent levels, P th2 is the threshold voltage between the second set of adjacent two-step levels, P th3 is the threshold voltage between the third set of two adjacent levels, is the average optical power of the optical signal, OMA outer is the OMA value actually obtained in step S100A, and 3 represents the number of groups of two adjacent levels.

[0086] In the first test method embodiment of the present application, in step S210A, it is necessary to determine the periodic distribution of the average optical power and the voltage amplitude variation period through the intersection of the electrical signal. Figure 7 As shown, it can be seen that in actual multi-order modulation, the location of the cross point in the eye diagram is not easy to find, which makes the calculation and implementation of the solution difficult and reduces the accuracy of the calculation result. In addition, in step S220A, it is necessary to ave and OMA values ​​to calculate multiple voltage thresholds. aveThe calculation of has already had calculation errors, and the OMA value obtained in step S100A also has errors. Combining the two and calculating multiple voltage thresholds in a fixed calculation method will also cause large errors in the calculation of multiple voltage thresholds. Figure 7 As shown, it can also be seen that the distribution of eye heights between the multiple levels is uneven. In step S220A, the overall average optical power P ave , the number of groups of two adjacent levels and the OMA value representing the overall optical power amplitude are used as calculation parameters. This method ignores the details of the uneven distribution of actual eye heights between different levels, so that the voltage threshold corresponding to each group of two adjacent levels obtained in the end has a large deviation from the actual voltage threshold.

[0087] S300A: Perform regional sampling on the eye diagram based on the period distribution of the voltage amplitude variation period to obtain a sampling histogram.

[0088] In the first test method embodiment of the present application, it is necessary to sample a sampling area within a voltage amplitude change period in the eye diagram to obtain a sampling histogram. The subsequent TDEC value is calculated based on the sampling histogram. Different communication technology standards for optical communications specify different sampling areas. After a clear period distribution is obtained in step S200A, the corresponding sampling area can be sampled and processed in actual applications according to the provisions of the relevant standards. However, because the intersection point based on which the period distribution is determined in step S200A is difficult to obtain, the determined period distribution has a certain deviation, which will affect the subsequent calculation of the TDEC value.

[0089] S400A: Output a TDEC value based on the sampled histogram and multiple voltage thresholds.

[0090] In the first test method embodiment of the present application, the TEDC value can be calculated based on the obtained sampling histogram and multiple voltage thresholds according to the definition of the communication technology standard. However, because the multiple voltage thresholds and sampling histograms obtained in the previous steps have certain deviations, there is a large error between the TDEC value obtained by the first test method and the actual TDEC value, which often has a great impact on the test and subsequent product applications.

[0091] In order to solve the problem of inaccurate TDEC value and OMA value test caused by the nonlinearity of optical devices and the dispersion of optical fibers, and the problem that some code types cannot realize OMA value calculation, the embodiment of the present application also provides a second test method based on the above Figure 4 The first tester 320 described in the embodiment or the above Figure 5The second tester 330 described in the embodiment executes the second test method, and the second test method obtains the distribution of the voltage amplitude of multiple sampling points in the eye diagram within a multi-order level range based on a statistical method. Because the voltage amplitude changes of multiple sampling points are obtained based on actual optical devices and optical signals after optical fiber transmission, the actual statistical results will also change with the actual transmission of the optical signal. The second test method calculates the TDEC value and the OMA value based on the statistical results. Compared with the calculation scheme based on a fixed calculation formula in the first test method, the distortion of the optical signal caused by the transmission can be taken into consideration, thereby increasing the calculation accuracy of the TDEC value and the OMA value. Specifically, Fig. 9 As shown, the second test method includes the following steps S100B-S300B:

[0092] S100B, obtain the eye diagram.

[0093] In some possible implementations, first, the noise standard deviation of the test circuit 300 is determined when there is no light input to the optical transmitter 2000. For example, Figure 4 The noise standard deviation of the oscilloscope 310 in the illustrated embodiment, or, as determined by Figure 5 The noise standard deviation of the second tester 330 with integrated oscilloscope function in the embodiment shown. Secondly, the optical transmitter 2000 repeatedly sends the optical signal for testing, and the optical fiber interface 100 in the sampling test system 1000 collects the optical signal. The collected optical signal is converted into an electrical signal by the photodetector 200 and output to the test circuit 300. In some examples, such as Figure 4 As shown, the oscilloscope 310 of the test circuit 300 generates an eye diagram based on the electrical signal, and the first tester 320 obtains the eye diagram generated by the oscilloscope 310. In some examples, such as Figure 5 As shown, the second tester 330 of the test circuit 300 generates an eye diagram based on an integrated oscilloscope function.

[0094] In some possible implementations, such as Figure 4 The oscilloscope 310 shown or Figure 5 The second tester 330 shown can also optimize and equalize the signal-to-noise ratio of the processed data based on the reference equalizer during the process of generating the eye diagram.

[0095] S200B, sampling and processing the eye diagram to obtain amplitude distribution information.

[0096] In some possible implementations, such as Figure 7As shown, the eye diagram is actually obtained. The eye diagram can be sampled to obtain multiple sampling points, and the voltage amplitudes of the electrical signals at the multiple sampling points can be statistically analyzed to obtain amplitude distribution information. The amplitude distribution information is used to describe the distribution of the voltage amplitudes of the electrical signals at the multiple sampling points within a multi-level range.

[0097] In some examples, the amplitude distribution information may be stored in a storage device or cache device of the test circuit 300 in the form of a data table entry. In some examples, the data table entry corresponding to the amplitude distribution information includes voltage amplitudes of multiple sampling points, each of which has a corresponding voltage amplitude value. Statistics may be performed on multiple sampling points according to different amplitude values ​​to obtain the following: Fig.10 The statistical chart form shown. Fig.10 In , the ordinate is the amplitude value distribution of the voltage amplitude existing in multiple sampling points, and the abscissa is the number of occurrences of the same amplitude value in multiple sampling points. Fig.10 It is a visual representation of amplitude distribution information.

[0098] In some examples, the eye diagram or the eye diagram after equalization optimization may be resampled to 8 times the sampling rate to obtain amplitude distribution information. Exemplarily, the resampling method is spline difference.

[0099] S300B. Output the first test result and / or the second test result according to the amplitude distribution information.

[0100] In some possible implementations, the first test result and / or the second test result can be output according to the amplitude distribution information. Among them, the first test result is used to indicate the TDEC value of the optical transmitter 2000, and the second test result is used to indicate the OMA value of the optical transmitter 2000. In the embodiment of the present application, the distribution of the voltage amplitude in the amplitude distribution information is related to the actual transmission of the optical signal. In the actual transmission process, the optical signal carries multi-order modulated data information. When the transmission of the optical signal is affected by the transmission of the optical device and the optical fiber and distorted, after the optical signal is photoelectrically converted to obtain an eye diagram, this distortion will exist in each level of the eye diagram. And, in actual applications, the distortion presented at each level is likely to be different and unevenly distributed. In the first test method, a fixed calculation formula is used to calculate the OMA value, and only the difference between the highest level and the lowest level is considered in the calculation process. In the second test method, by sampling the eye diagram, the multiple sampling points obtained are randomly distributed between the multi-levels. Each sampling point corresponds to the voltage amplitude of an electrical signal of a certain level under actual transmission. The amplitude distribution information of the voltage amplitude of the multi-level under actual transmission can be determined by statistical means. The amplitude distribution information includes the distribution of the voltage amplitude of the electrical signal of multiple sampling points within the multi-level range. Therefore, based on the amplitude distribution information, the distortion effect of time transmission between the multi-levels can be taken into account, and the first test result and / or the second test result obtained by the second test method are more accurate than those obtained by the first test method.

[0101] In some possible implementations, step S300B may be based on the following Fig.11 The sub-operations of steps S310B to S320B shown implement the calculation of the first test result:

[0102] S310B, obtaining multiple voltage thresholds according to the amplitude distribution information.

[0103] In an embodiment of the present application, multiple voltage thresholds are used to define level intervals of multiple groups of adjacent levels within a multi-level range, and each of the multiple voltage thresholds is used to define a level interval of one group of adjacent levels in the multiple groups of adjacent levels.

[0104] In some possible implementations, for each group of two adjacent levels in the plurality of groups of adjacent levels, step S310B may be based on the following: Fig.12 The sub-operations of steps S311B to S312B shown implement the calculation of the voltage threshold:

[0105] S311B, obtaining a first amplitude and a second amplitude according to the voltage amplitudes of the electrical signals at the plurality of sampling points in the amplitude distribution information.

[0106] In the embodiment of the present application, the first level and the second level are two levels in the first group of adjacent levels. The first amplitude is the majority amplitude among multiple amplitudes corresponding to the first level in the amplitude distribution information, and the second amplitude is the majority amplitude among multiple amplitudes corresponding to the second level in the amplitude distribution information.

[0107] S312B: Obtain a voltage threshold for defining a first level and a second level according to the first amplitude and the second amplitude.

[0108] In some examples, when both the first level and the second level have a unique mode amplitude, that is, the first amplitude is the unique mode amplitude value corresponding to the first level, and the second amplitude is the unique mode amplitude value corresponding to the second level, illustratively, the voltage threshold for defining the first level and the second level can be obtained according to the average value of the first amplitude and the second amplitude. Exemplarily, an amplitude value within a certain range can also be selected based on the unique mode amplitude, and the voltage threshold for defining the first level and the second level can be obtained according to the average value of the selected amplitude.

[0109] In some examples, when the first level and / or the second level have multiple mode amplitudes, that is, the first amplitude and / or the second amplitude can have multiple values, the voltage threshold for defining the first level and the second level can be obtained by the following operations: first, in the amplitude distribution information, the first amplitude is used as the sampling center and the first amplitude difference is used as the sampling area width to obtain the first amplitude set; in the amplitude distribution information, the second amplitude is used as the sampling center and the second amplitude difference is used as the sampling area width to obtain the second amplitude set. Then, according to the average amplitude of the first amplitude set and the second amplitude set, the voltage threshold for defining the first level and the second level is obtained. Exemplarily, the range in which the amplitude drops by 3 dB can be used as the first amplitude difference and / or the second amplitude difference.

[0110] In the method of calculating multiple voltage thresholds in step S200A of the first test method, it is difficult to differentiate the intersection points of the multiple levels. At the same time, the OMA value and the average optical power P aveAll of them are information obtained from the overall amplitude difference of the eye diagram. Because the transmission of the optical signal is affected by factors such as the nonlinear characteristics of the optical device and the dispersion of the optical fiber F, the eye height distribution of the eye diagram between different levels in the actual eye diagram varies unevenly. However, the first test method does not take into account the problem of deviation in the eye height distribution of multiple sub-eye diagrams between multi-order levels. Therefore, there will be calculation deviations in the multiple voltage thresholds obtained in this way. In addition, because there is also a certain deviation in the calculation of the OMA value in the first test method, this will make the deviation of the multiple voltage thresholds calculated based on the OMA value in the first test method larger. In the embodiment of the present application, the mode amplitude of each level is obtained based on data statistics, and the value of the mode amplitude is related to the transmission of the optical signal, and multiple voltage thresholds are calculated based on the mode amplitude of each level of the multi-order level. The characteristics of uneven distribution of eye heights between multi-order levels can be taken into account, and the accuracy of the calculated multiple voltage thresholds is higher.

[0111] S320B, output a first test result according to multiple voltage thresholds.

[0112] In some possible implementations, a regional histogram can be obtained by sampling in the eye diagram. A first test result is output according to the regional histogram and multiple voltage thresholds. Different communication technology standards specify specific sampling period positions of the regional histogram. Therefore, it is also necessary to determine the voltage amplitude change period distribution of the electrical signal in the eye diagram, and implement sampling from the corresponding period area according to the determined voltage amplitude change period distribution. At this time, step S320B can also include the following: Fig.13 Sub-operations of steps S321B to S323B shown:

[0113] S321B. Obtain the voltage amplitude variation period distribution of the electrical signal of the eye diagram according to the amplitude distribution information.

[0114] In the embodiment of the present application, the voltage amplitude variation period distribution of the electrical signal of the eye diagram can be obtained based on the time information of the electrical signal at multiple sampling points.

[0115] In some examples, the voltage amplitude variation period distribution can be calculated by the following operations: first, the multiple sampling points are divided into sampling points at multiple moments according to the time information of the electrical signals at the multiple sampling points. Secondly, the amplitude variance of the sampling points at the first moment is obtained according to the distribution information of the voltage amplitude of the electrical signals of the multiple sampling points at the first moment in the multiple moments within the multi-order level range, and the amplitude variance at each moment in the multiple moments is obtained by analogy. The schematic diagram of the obtained amplitude variance is shown in FIG. Fig.14As shown. Then, according to the amplitude variance at each moment, the maximum value of the amplitude variance of the electrical signal of the eye diagram in each amplitude variation cycle is obtained. Finally, according to the maximum value of the amplitude variance of the electrical signal of the eye diagram in each amplitude variation cycle, the period distribution of the electrical signal of the eye diagram in each amplitude variation cycle is obtained, wherein the period distribution includes the midpoint of the cycle, the starting point of the cycle and the end point of the cycle.

[0116] In an embodiment of the present application, the midpoint of each voltage amplitude change cycle can be determined according to the maximum value of the amplitude variance of the electrical signal of the eye diagram in each amplitude change cycle. The period connection point of two adjacent voltage amplitude change cycles can be calculated according to the average value of the midpoints of two adjacent cycles, and the period connection point is the period end point of the previous voltage amplitude change cycle in the two adjacent voltage amplitude change cycles, and is also the period starting point of the next voltage amplitude change cycle in the two adjacent voltage amplitude change cycles. By calculating the maximum value of the amplitude variance, the period starting point, period midpoint and period end point of each voltage amplitude change cycle can be calculated. In the first test method, the number of intersections of electrical signals of different levels in the eye diagram is required to determine the period starting point and period end point. In this way, it is more difficult to find the intersection point, and as the number of levels increases, the position of the intersection point will also change, so that the difficulty of finding the intersection point will also increase, which will introduce more errors into the calculation of the period distribution. Compared with the first test method in which the period distribution is calculated by using intersection points, the second test method determines the period distribution by statistically analyzing the amplitude variance at different times. This method does not require searching for intersection points, and because the amplitude distribution information is easy to obtain, the first tester 320 or the second tester 330 can obtain the period distribution based on a simple formula.

[0117] S322B, performing regional sampling on the eye diagram according to the voltage amplitude variation period distribution to obtain a regional histogram.

[0118] In the embodiment of the present application, the regional histogram includes some sampling points among the plurality of sampling points, and the time difference between the timing of the electrical signals of the some sampling points and the midpoint of the period of the corresponding voltage amplitude variation period belongs to the first time length.

[0119] In some examples, such as Fig.15 As shown in Figure (a), the absolute value of the first time length is 0.1 amplitude change cycle length. In the embodiment of the present application, the midpoint of the voltage amplitude change cycle is 0.5 amplitude change cycle point, and sampling can be performed on part or all of the area within the range between 0.4 amplitude change cycle point and 0.6 amplitude change cycle point to obtain a regional histogram, and the obtained regional histogram includes all voltage amplitude data of the electrical signal within the sampling period range.

[0120] In some examples, such as Fig.15As shown in FIG. (b), two regional histograms can be obtained by sampling two points in a voltage amplitude variation cycle, namely, a first regional histogram and a second regional histogram. For example, according to the provisions in different communication technology standards, the corresponding amplitude variation cycle point can be selected as the regional midpoint of the regional histogram. For example, Fig.15 As shown in Figure (b), the first area of ​​the first amplitude change period of the eye diagram can be sampled with the 0.45 amplitude change period point as the area center to obtain the first area histogram; the second area of ​​the first amplitude change period can be sampled with the 0.55 amplitude change period point as the area center to obtain the second area histogram. Exemplarily, according to the provisions in different communication technology standards, different time lengths can be selected as the area period length of the area histogram. For example, the 0.04 amplitude change period length can be used as the area period length of the first area histogram and the second area histogram.

[0121] S323B, output a first test result according to the voltage threshold and the area histogram.

[0122] In some possible implementations, the first test result may be obtained based on the following calculation method:

[0123] In the first step, each region histogram is normalized to obtain a series of optical power values ​​y with a power interval of Δy. i The number of sampling points in each power interval is divided by the total number of sampling points in the corresponding area histogram to calculate the ratio of the number of sampling points in each power interval F(y i ). After normalization, all F(y i ) is equal to 1.

[0124] The second step is to calculate the sampling point ratio F(y i ), calculate the cumulative probability function corresponding to the multiple voltage thresholds. Exemplarily, taking the case where the regional histogram includes the first regional histogram and the second regional histogram, when the multi-level modulation is 4-level modulation, for the voltage thresholds P around level 0 and level 1 th1 The voltage threshold P can be calculated using the following formula: th1 The corresponding cumulative probability function CF L1 (y i ):

[0125]

[0126] Wherein, L represents the first region histogram, L1 is the voltage threshold P between level 0 and level 1 in the first region histogram th1 The voltage threshold P can be calculated by the above formula. th1The corresponding cumulative probability function CF L1 (y i ). Similarly, the cumulative probability function CF in the first region histogram can be calculated: L2 (y i ) and the cumulative probability function CF L3 (y i ). L2 is the voltage threshold P between level 1 and level 2 in the first region histogram. th2 L3 is the voltage threshold P between level 2 and level 3 in the first region histogram. th3 Similarly, the cumulative probability function CF of the second region histogram can also be realized R1 (y i ), cumulative probability function CF R2 (y i ) and the cumulative probability function CF R3 (y i ). L represents the second region histogram, R1 is the voltage threshold P between level 0 and level 1 in the second region histogram. th1 R2 is the voltage threshold P between level 1 and level 2 in the second region histogram. th2 R3 is the voltage threshold P between level 2 and level 3 in the second region histogram. th3 The number of Fig.16 As shown, the cumulative probability function CF corresponding to the first area histogram Li (y i ) distribution, where the horizontal axis represents the variable value, the vertical axis represents the cumulative probability, and lines ①, ② and ③ are the cumulative probability function distributions corresponding to the three threshold voltages in the first region histogram.

[0127] The third step is to use different σ G Under the value, with each voltage threshold as the center, the root mean square (RMS) is calculated as the aforementioned σ G The Gaussian probability density function of the value is used to calculate the threshold voltage P th1 The corresponding Gaussian probability density function G th1 (y i ) as an example, G th1 (y i ) can be defined and estimated by the following formula:

[0128]

[0129]

[0130] In the formula, C eqis the coefficient of the reference equalizer noise enhancement, which can refer to the normalized noise power density spectrum N(f) of the equalizer input and the normalized frequency response H of the reference equalizer eq The specific calculation formula is as follows:

[0131]

[0132] Where f is the value of all frequencies within the frequency range of the signal; N(f) is the normalized noise power density spectrum, which is equivalent to white noise filtered by a fourth-order Bessel-Thomson response filter with a bandwidth of 19.34 GHz.

[0133] For the voltage threshold P th2 The corresponding Gaussian probability density function G th2 (y i ) and the voltage threshold P th3 The corresponding Gaussian probability density function G th3 (y i ), can be calculated using the above method.

[0134] Step 4: Based on the cumulative probability function obtained in step 2 and the Gaussian probability density function obtained in step 3, the symbol error rate (SEC) corresponding to the multiple voltage thresholds is obtained. For example, taking the multi-level as the 4-level level as an example, for the threshold voltage P in the histogram of the first region th1 , the corresponding cumulative probability function CF L1 (y i ) is multiplied by the Gaussian probability density function G th1 (y i ), the threshold voltage P in the first region histogram can be obtained th1 SER L1 Similarly, the threshold voltage P in the first region histogram can be calculated. th2 and threshold voltage P th3 The corresponding SER L2 and SER L3 The threshold voltage P in the second region histogram can also be calculated. th1 , threshold voltage P th2 and threshold voltage P th3 The corresponding SER R1 SER R2 and SER R3 .

[0135] Step 5: SER L1 SER L2 and SER L3 Sum the noise associated with the first region histogram to obtain the total noise SERL . R1 SER R2 and SER R3 The sum is performed to obtain the noise sum SER associated with the second region histogram R .

[0136] Step 6: SER L According to SER R , calculate the TDEC value. For example, taking the calculation of the TDECQ value as an example, when SER L According to SER R The larger value is close to 4.8×10 -4 The TDECQ value is calculated based on the following formula:

[0137]

[0138] In the formula, OMA outer is the OMA value actually calculated, which can be calculated when calculating the first test result, or the result obtained when calculating the second test result can be used; Q t is 3.414, which is consistent with the bit error rate and symbol error rate of Gray-coded PAM4; R is the RMS noise that the receiver can add, which is calculated as follows:

[0139]

[0140] In the formula, σ G is the coefficient of reference equalizer noise enhancement, σ S To make SER L According to SER R The larger value is close to 4.8×10 -4 The noise added when .

[0141] Through the above operation, the first test result about the TDEC value can be output. Compared with the first test method, the embodiment of the present application can significantly improve the accuracy of the calculation. At the same time, in the case of poor eye diagram quality, the output of the first test result can also be achieved.

[0142] In some possible implementations, step S300B may be based on the following Fig.17 The sub-operations of steps S310B' to S320B' shown implement the calculation of the second test result:

[0143] S310B′, obtaining a third amplitude and a fourth amplitude according to the amplitude distribution information.

[0144] In the embodiment of the present application, the third amplitude is a majority amplitude among multiple amplitudes of the highest level in the multi-level levels, and the fourth amplitude is a majority amplitude among multiple amplitudes of the lowest level in the multi-level levels.

[0145] In some examples, when both the highest level and the lowest level have unique mode amplitudes, that is, the third amplitude is the unique mode amplitude value corresponding to the highest level, and the fourth amplitude is the unique mode amplitude value corresponding to the lowest level, the voltage threshold for defining the highest level and the lowest level can be obtained according to the average value of the third amplitude and the fourth amplitude.

[0146] In some examples, when the highest level and / or the lowest level have multiple mode amplitudes, that is, the third amplitude and / or the fourth amplitude can have multiple values, the voltage threshold for defining the highest level and the lowest level can be obtained by the following operations: first, in the amplitude distribution information, the third amplitude is used as the sampling center and the third amplitude difference is used as the sampling area width to obtain the third amplitude set; in the amplitude distribution information, the fourth amplitude is used as the sampling center and the fourth amplitude difference is used as the sampling area width to obtain the fourth amplitude set. Then, according to the average amplitude of the third amplitude set and the fourth amplitude set, the voltage threshold for defining the highest level and the lowest level is obtained. Exemplarily, the range in which the amplitude drops by 3dB can be used as the third amplitude difference and / or the fourth amplitude difference. The relevant description of the third amplitude and the fourth amplitude can refer to the relevant description of the first amplitude and the second amplitude mentioned above, which will not be repeated here.

[0147] S320B′: output a second test result according to the third amplitude and the fourth amplitude.

[0148] A second test result is outputted according to the average amplitude of the third amplitude set and the fourth amplitude set.

[0149] In some examples, when both the highest level and the lowest level have unique mode amplitudes, that is, the third amplitude is the unique mode amplitude value corresponding to the highest level, and the fourth amplitude is the unique mode amplitude value corresponding to the lowest level, the voltage threshold for defining the highest level and the lowest level can be obtained according to the average value of the third amplitude and the fourth amplitude.

[0150] In some examples, when the highest level and / or the lowest level have multiple mode amplitudes, that is, the third amplitude and / or the fourth amplitude can have multiple values, the voltage threshold used to define the highest level and the lowest level can be obtained by the following operations: first, in the amplitude distribution information, the third amplitude is used as the sampling center and the third amplitude difference is used as the sampling area width to obtain the third amplitude set; in the amplitude distribution information, the fourth amplitude is used as the sampling center and the fourth amplitude difference is used as the sampling area width to obtain the fourth amplitude set. Then, according to the difference in the average amplitude of the third amplitude set and the fourth amplitude set, the second test result is obtained. Exemplarily, the range in which the amplitude drops by 3dB can be used as the third amplitude difference and / or the fourth amplitude difference. For the description of the third amplitude and the fourth amplitude, reference can be made to the description of the first amplitude and the second amplitude, which will not be repeated here.

[0151] In an embodiment of the present application, the mode amplitude of each level is obtained based on data statistics, the value of the mode amplitude is related to the transmission of the optical signal, and multiple voltage thresholds are calculated based on the mode amplitude of each level of the multi-level. The uneven distribution of eye heights between multi-levels can be taken into account, and the calculated OMA value has a higher accuracy. At the same time, in the second test method, the OMA value is calculated based on the amplitude distribution information, and there is no need to find the continuous highest level and the continuous lowest level in the eye diagram, which gets rid of the limitation of the data pattern, so that the scheme can be applied to more different data pattern application scenarios.

[0152] The embodiment of the present application provides a test method, tester and test equipment for an optical transmitter. In the test method for the optical transmitter, the eye diagram is sampled to obtain multiple sampling points, and the voltage amplitude of the electrical signal at the multiple sampling points is statistically analyzed to obtain amplitude distribution information, and the amplitude distribution information is used to describe the distribution information of the voltage amplitude of the electrical signal at the multiple sampling points within a multi-order level range. According to the amplitude distribution information, the first test result and / or the second test result are output to implement the test of the performance index of the optical transmitter. Among them, the first test result is used to indicate the TDEC value of the optical transmitter, and the second test result is used to indicate the OMA value of the optical transmitter. The change of the voltage amplitude in the amplitude distribution information is related to the actual transmission quality of the optical signal, which avoids the calculation error caused by the influence of the nonlinear characteristics of the optical device and the dispersion of the optical fiber on the optical signal, and can improve the accuracy of the test results.

[0153] The present application also provides a computer-readable storage medium, which includes instructions. When the instructions are executed on a processor, the processor executes the second test method (e.g. Fig. 9 , Fig.11 , Fig.12 , Fig.13 and Fig.17 ).

[0154] The processor involved in the embodiments of the present application may be a chip. For example, it may be a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a system on chip (SoC), a central processor unit (CPU), a network processor (NP), a digital signal processor (DSP), a microcontroller unit (MCU), a programmable logic device (PLD), or other integrated chips.

[0155] The memory involved in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0156] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0157] Those of ordinary skill in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0158] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0159] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0160] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one device or distributed on multiple devices. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0161] In addition, each functional module in each embodiment of the present application may be integrated into one device, or each module may exist physically separately, or two or more modules may be integrated into one device.

[0162] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using a software program, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loading and executing a computer program instruction on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (Digital Subscriber Line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or may contain one or more servers, data centers and other data storage devices that can be integrated with a medium. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (eg, a solid state disk (SSD)).

[0163] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for testing an optical transmitter, characterized in that: The method comprises: Obtaining an eye diagram, wherein the eye diagram is used to describe the change of the voltage amplitude of the electrical signal over time within a multi-level range, wherein the electrical signal is obtained by converting an optical signal received by an optical fiber interface, wherein the optical fiber interface is connected to the optical transmitter via an optical fiber, and wherein the optical signal is a multi-level modulated signal; Sampling the eye diagram to obtain a plurality of sampling points, and performing statistics on the voltage amplitudes of the electrical signals at the plurality of sampling points to obtain amplitude distribution information, wherein the amplitude distribution information is used to describe the distribution of the voltage amplitudes of the electrical signals at the plurality of sampling points within a multi-level range; A first test result is output according to the amplitude distribution information, where the first test result is used to indicate a TDEC value of the optical transmitter.

2. The method according to claim 1, characterized in that Outputting a first test result according to the amplitude distribution information includes: Obtaining a plurality of voltage thresholds according to the amplitude distribution information, wherein the plurality of voltage thresholds are used to define level intervals of a plurality of groups of adjacent levels within the multi-level range, and each of the plurality of voltage thresholds is used to define a level interval of a group of adjacent levels in the plurality of groups of adjacent levels; The first test result is output according to the multiple voltage thresholds.

3. The method according to claim 2, characterized in that The obtaining a plurality of voltage thresholds according to the amplitude distribution information comprises: For a first group of adjacent two-step levels among the plurality of groups of adjacent levels, the following operations are performed to obtain a voltage threshold for defining a level interval of the first group of adjacent levels: Obtaining a first amplitude and a second amplitude according to the voltage amplitudes of the electrical signals at the plurality of sampling points, wherein the first amplitude is a majority amplitude among a plurality of amplitudes corresponding to a first level in the amplitude distribution information, the second amplitude is a majority amplitude among a plurality of amplitudes corresponding to a second level in the amplitude distribution information, and the first level and the second level are two levels in the first group of adjacent levels; A voltage threshold for defining the first level and the second level is obtained according to the first amplitude and the second amplitude.

4. The method according to claim 3, characterized in that The step of obtaining a voltage threshold for defining the first level and the second level according to the first amplitude and the second amplitude includes: A first amplitude set is obtained by taking the maximum value of the first amplitude as the sampling center and the first amplitude difference as the width of the sampling area in the amplitude distribution information; A second amplitude set obtained by taking the maximum value of the second amplitude in the amplitude distribution information as the sampling center and the second amplitude difference as the sampling area width; A voltage threshold for defining the first level and the second level is obtained according to the average amplitude of the first amplitude set and the second amplitude set.

5. The method according to any one of claims 2 to 4, characterized in that: Outputting the first test result according to the multiple voltage thresholds includes: Obtaining a voltage amplitude variation period distribution of the electrical signal of the eye diagram according to time information of the electrical signals of the plurality of sampling points; Performing regional sampling in the eye diagram according to the voltage amplitude variation period distribution to obtain a regional histogram, wherein the regional histogram includes some sampling points among the multiple sampling points, and the time difference between the moment of the electrical signal of the some sampling points and the midpoint of the period of the voltage amplitude variation period to which they belong belongs to a first time length; The first test result is output according to the multiple voltage thresholds and the area histogram.

6. The method according to claim 5, characterized in that The step of obtaining the voltage amplitude variation period distribution of the electrical signal of the eye diagram according to the time information of the electrical signal at the plurality of sampling points comprises: Dividing the plurality of sampling points into sampling points at a plurality of moments according to time information of the electrical signals of the plurality of sampling points; According to the distribution information of the voltage amplitude of the electrical signal at the plurality of sampling points at the first moment among the plurality of moments within the multi-level range, the amplitude variance of the sampling points at the first moment is obtained, and the amplitude variance at each moment among the plurality of moments is obtained by analogy; According to the amplitude variance at each moment, obtaining the maximum value of the amplitude variance of the electrical signal of the eye diagram in each amplitude variation cycle; The period distribution of the electrical signal of the eye diagram in each amplitude variation period is obtained according to the maximum value of the amplitude variance of the electrical signal of the eye diagram in each amplitude variation period, wherein the period distribution includes a period midpoint, a period start point and a period end point.

7. The method according to claim 5 or 6, characterized in that: The absolute value of the first time length is 0.1 amplitude variation cycle length.

8. The method according to claim 7, characterized in that The step of performing regional sampling on the eye diagram according to the voltage amplitude variation period distribution to obtain a regional histogram comprises: Sampling is performed in the first area of ​​the first amplitude change period of the eye diagram with the 0.45 amplitude change period point as the area center to obtain a first area histogram; sampling is performed in the second area of ​​the first amplitude change period with the 0.55 amplitude change period point as the area center to obtain a second area histogram.

9. The method according to any one of claims 1 to 8, characterized in that: The optical signal is a 4th order modulation signal, and the TDEC value is a TDECQ value.

10. The method according to any one of claims 1 to 9, characterized in that: The method further comprises: A second test result is output according to the amplitude distribution information, where the second test result is used to indicate the OMA value of the optical transmitter.

11. The method according to claim 10, characterized in that Outputting a second test result according to the amplitude distribution information includes: According to the amplitude distribution information, a third amplitude and a fourth amplitude are obtained, wherein the third amplitude is a majority amplitude among multiple amplitudes of the highest level in the multi-level levels, and the fourth amplitude is a majority amplitude among multiple amplitudes of the lowest level in the multi-level levels; The second test result is output according to the third amplitude and the fourth amplitude.

12. The method according to claim 11, characterized in that Outputting the second test result according to the third amplitude and the fourth amplitude includes: A third amplitude set is obtained by taking the maximum value of the third amplitude in the amplitude distribution information as the sampling center and taking the third amplitude difference as the sampling area width; A fourth amplitude set obtained by taking the maximum value of the fourth amplitude in the amplitude distribution information as the sampling center and taking the fourth amplitude difference as the sampling area width; The second test result is output according to the difference between the average amplitudes of the third amplitude set and the fourth amplitude set.

13. A method for testing an optical transmitter, characterized in that: The method comprises: Obtaining an eye diagram, where the eye diagram is used to describe how the amplitude of an electrical signal changes over time, where the electrical signal is a signal including multiple levels obtained by converting an optical signal received by an optical fiber interface, where the optical fiber interface is connected to the optical transmitter via an optical fiber, and where the optical signal is a multi-level modulated signal; Sampling the eye diagram to obtain a plurality of sampling points, and performing statistics on the voltage amplitudes of the electrical signals at the plurality of sampling points to obtain amplitude distribution information, wherein the amplitude distribution information is used to describe the distribution of the voltage amplitudes of the electrical signals at the plurality of sampling points within a multi-level range; A second test result is output according to the amplitude distribution information; the second test result is used to indicate the OMA value of the optical transmitter.

14. The method according to claim 13, characterized in that Outputting a second test result according to the amplitude distribution information includes: Obtaining a third amplitude and a fourth amplitude according to the amplitude distribution information, wherein the third amplitude is a majority amplitude among a plurality of amplitudes corresponding to a highest level in the amplitude distribution information, and the fourth amplitude is a majority amplitude among a plurality of amplitudes corresponding to a lowest level in the amplitude distribution information; The second test result is output according to the third amplitude and the fourth amplitude.

15. The method according to claim 14, characterized in that Outputting the second test result according to the third amplitude and the fourth amplitude includes: A third amplitude set obtained by taking the third amplitude as a sampling center and the third amplitude difference as a sampling area width in the amplitude distribution information; A fourth amplitude set obtained by taking the fourth amplitude as a sampling center and the fourth amplitude difference as a sampling area width in the amplitude distribution information; The second test result is output according to the difference between the average amplitudes of the third amplitude set and the fourth amplitude set.

16. A tester, characterized in that: The tester is used to: Obtaining an eye diagram, wherein the eye diagram is used to describe the change of the voltage amplitude of the electrical signal over time within a multi-level range, wherein the electrical signal is obtained by converting an optical signal received by an optical fiber interface, wherein the optical fiber interface is connected to the optical transmitter via an optical fiber, and wherein the optical signal is a multi-level modulated signal; Sampling the eye diagram to obtain a plurality of sampling points, and performing statistics on the voltage amplitudes of the electrical signals at the plurality of sampling points to obtain amplitude distribution information, wherein the amplitude distribution information is used to describe the distribution of the voltage amplitudes of the electrical signals at the plurality of sampling points within a multi-level range; A first test result is output according to the amplitude distribution information, where the first test result is used to indicate a TDEC value of the optical transmitter.

17. The tester according to claim 16, characterized in that: The optical signal is a 4th order modulation signal, and the TDEC value is a TDECQ value.

18. The tester according to claim 16 or 17, characterized in that: The tester is also used to: A second test result is output according to the amplitude distribution information, where the second test result is used to indicate the OMA value of the optical transmitter.

19. The tester according to any one of claims 16 to 18, characterized in that: The obtaining of the eye diagram comprises: The electrical signal is received, and signal processing is performed on the electrical signal to obtain the eye diagram.

20. The tester according to any one of claims 16 to 18, characterized in that: The obtaining of the eye diagram comprises: Enter the eye diagram.

21. A tester, characterized in that: The tester is used to: Obtaining an eye diagram, wherein the eye diagram is used to describe the change of the voltage amplitude of the electrical signal over time within a multi-level range, wherein the electrical signal is obtained by converting an optical signal received by an optical fiber interface, wherein the optical fiber interface is connected to the optical transmitter via an optical fiber, and wherein the optical signal is a multi-level modulated signal; Sampling the eye diagram to obtain a plurality of sampling points, and performing statistics on the voltage amplitudes of the electrical signals at the plurality of sampling points to obtain amplitude distribution information, wherein the amplitude distribution information is used to describe the distribution of the voltage amplitudes of the electrical signals at the plurality of sampling points within a multi-level range; A second test result is output according to the amplitude distribution information; the second test result is used to indicate the OMA value of the optical transmitter.

22. The tester according to claim 21, characterized in that: The obtaining of the eye diagram comprises: The electrical signal is received, and signal processing is performed on the electrical signal to obtain the eye diagram.

23. The tester according to claim 21, characterized in that: The obtaining of the eye diagram comprises: Enter the eye diagram.

24. A testing system, characterized in that: The test system comprises an optical fiber interface, a photoelectric detector and a test circuit; wherein: The optical fiber interface is used to: connect to an optical transmitter via an optical fiber and receive an optical signal from the optical transmitter, wherein the optical signal is a multi-order modulated signal; The photodetector is used to: convert the optical signal into an electrical signal; The test circuit is used to: According to the electrical signal, an eye diagram is obtained; the eye diagram is used to describe the change of the voltage amplitude of the electrical signal over time within a multi-level range; Sampling the eye diagram to obtain a plurality of sampling points, and performing statistics on the voltage amplitudes of the electrical signals at the plurality of sampling points to obtain amplitude distribution information, wherein the amplitude distribution information is used to describe the distribution of the voltage amplitudes of the electrical signals at the plurality of sampling points within a multi-level range; A first test result and / or a second test result is output according to the amplitude distribution information, wherein the first test result is used to indicate a TDEC value of the optical transmitter, and the second test result is used to indicate an OMA value of the optical transmitter.

25. The test system according to claim 24, characterized in that: The test circuit includes an oscilloscope and a first tester; wherein: The oscilloscope is used to: generate the eye diagram according to the electrical signal; The first tester is used to: obtain the eye diagram, sample the eye diagram to obtain multiple sampling points, and count the voltage amplitudes of the electrical signals at the multiple sampling points to obtain amplitude distribution information; and output the first test result and / or the second test result according to the amplitude distribution information.

26. The test system according to claim 24, characterized in that The test circuit includes a second tester; the second tester is used for: Obtaining the eye diagram according to the electrical signal; Sampling the eye diagram to obtain a plurality of sampling points, and performing statistics on the voltage amplitudes of the electrical signals at the plurality of sampling points to obtain amplitude distribution information; The first test result and / or the second test result is output according to the amplitude distribution information.

27. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes instructions; when the instructions are executed on a processor, the processor executes the optical transmitter testing method as described in any one of claims 1 to 12, or executes the optical transmitter testing method as described in any one of claims 13 to 15.

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