Frequency response measurement method, device, system and storage medium

Abstract

The present application provides a frequency response measurement method, device, system and storage medium, relating to the technical field of frequency response measurement. The frequency response measurement system includes: a light source device; the light source device is configured to provide a continuous optical signal to the electro-optic modulator to be measured; a signal source device; the signal source device is configured to provide a pulse signal to the electro-optic modulator to be measured; wherein, adjacent pulses in the pulse signal have a fixed phase relationship; a measurement device; the measurement device is configured to collect the modulated optical signal output by the electro-optic modulator to be measured according to the optical signal and the pulse signal, and convert the modulated optical signal into an electrical signal; the electrical signal is used to calculate the frequency response of the electro-optic modulator to be measured; the frequency response includes at least a phase-frequency response. The present application can provide a technical solution with low measurement process complexity and capable of measuring the phase-frequency response of an electro-optic modulator.

Description

Technical Field

[0001] This application relates to the technical field of frequency response measurement, and particularly to a frequency response measurement method, device, system, and storage medium. Background Art

[0002] With the rapid development of the information age, the communication field, especially fiber optic communication systems, is rapidly evolving towards high speed, large capacity, and long distance. In high-frequency scenarios, traditional electrical interconnection technologies are restricted by physical mechanisms and structural processes such as the skin effect, dielectric loss, parasitic parameters, and electromagnetic radiation, making it difficult for the communication distance and rate to meet the interconnection requirements.

[0003] Optical interconnection technology, with advantages such as low loss (fiber optic transmission loss < 0.2 dB / km), high bandwidth (single-mode fiber bandwidth can reach the THz level), and electromagnetic interference resistance, has become the core solution for the next generation of high-speed communication. As a key device in the optical interconnection system, the electro-optic modulator converts electrical signals into optical signals, loads information by modulating the intensity, phase, or frequency of light, and directly determines the quality of the optical signal and the system performance.

[0004] For a large-bandwidth electro-optic modulator applied to a high-speed communication system, its frequency response directly affects the signal quality. The amplitude-frequency response determines the signal amplitude fidelity. Its unevenness can cause high-frequency component attenuation and time-domain pulse broadening, leading to inter-symbol interference (ISI) and deteriorating the bit error rate to an unacceptable level; the phase-frequency response determines the phase transmission linearity, and the group velocity dispersion (GVD) introduced by its non-linearity accumulates phase noise and directly destroys the carrier phase estimation in coherent communication.

[0005] Currently, methods for measuring the frequency response of electro-optic modulators include spectral analysis and electrical spectral analysis. Among them, spectral analysis directly measures in the optical domain through a spectral analyzer (OSA) or an optical vector analyzer (OVA). However, traditional spectral analyzers are limited by spectral resolution, and their starting measurement frequency and measurement resolution are usually limited to about 2.5 GHz (i.e., 0.02 nm @ 1550 nm), making it difficult to meet the requirements of high-frequency fine measurement. Although optical vector analyzers can directly obtain the amplitude and phase responses, commercial instruments are scarce and expensive (over one million yuan per unit), lacking general applicability; electrical spectral analysis uses a microwave network analyzer to apply a single-tone microwave signal with a frequency sweep to the measured Mach-Zehnder modulator, analyze the signal recovered by the auxiliary photodetector, and obtain the frequency response. This method is limited by the randomness of the input signal phase and cannot establish a "frequency-phase" deterministic correlation, so it cannot measure the phase-frequency response of the electro-optic modulator; moreover, the frequency response calibration of the auxiliary photodetector introduces error accumulations such as cable loss and device parasitic parameters in the high-frequency band, reducing the accuracy of the test results. Summary of the Invention

[0006] The present application provides a frequency response measurement method, device, system and storage medium, aiming to provide a technical solution with low measurement process complexity and capable of accurately measuring the phase-frequency response of an electro-optic modulator.

[0007] In a first aspect, the present application provides a frequency response measurement system for measuring an electro-optic modulator to be measured; the system includes:

[0008] A light source device; the light source device is used to provide a continuous optical signal to the electro-optic modulator to be measured;

[0009] A signal source device; the signal source device is used to provide a pulse signal to the electro-optic modulator to be measured; wherein, adjacent pulses in the pulse signal have a fixed phase relationship;

[0010] A measurement device; the measurement device is used to collect the modulated optical signal output by the electro-optic modulator to be measured according to the optical signal and the pulse signal, and convert the modulated optical signal into an electrical signal; the electrical signal is used to calculate the frequency response of the electro-optic modulator to be measured; the frequency response at least includes a phase-frequency response.

[0011] In the case of adopting the above technical solution, in the embodiment of the present application, adjacent pulses in the pulse signal provided by the signal source device to the electro-optic converter to be measured have a fixed phase relationship in the frequency domain. The electro-optic converter to be measured modulates the intensity, phase and / or frequency of the optical signal based on the pulse signal to obtain a modulated optical signal. The measurement device is used to convert the modulated optical signal into an electrical signal, and the electrical signal can be used to calculate the frequency response of the electro-optic modulator to be measured. Since adjacent pulses in the pulse signal input to the electro-optic converter to be measured have a fixed phase relationship in the frequency domain, it should be understood that when adjacent pulses of the input signal have a fixed phase relationship in the frequency domain, the consistency of the phase of the input signal can be ensured. This consistency eliminates the measurement error caused by phase randomness. Therefore, the phase-frequency response of the electro-optic modulator to be measured can be accurately calculated based on the electrical signal obtained from the pulse signal.

[0012] Furthermore, the frequency response measurement system provided by the embodiment of the present application only needs to provide an optical signal and a pulse signal to the electro-optic modulator to be measured, then collect the modulated optical signal output by the electro-optic modulator according to the optical signal and the pulse signal, and convert it into an electrical signal to calculate the frequency response of the electro-optic modulator to be measured by using the electrical signal, without recovering the signal from the photodetector and performing a complex signal processing process. Therefore, the measurement process complexity of the system provided by the embodiment of the present application is relatively low.

[0013] In a possible implementation manner, the pulse signal is a high-frequency electrical comb tooth signal;

[0014] The signal source device includes an optical frequency comb generator and a first photoelectric converter;

[0015] The optical frequency comb generator is used to generate an optical frequency comb signal;

[0016] The first optoelectronic converter is used to convert the optical frequency comb signal into a high-frequency electrical comb tooth signal and output the high-frequency electrical comb tooth signal to the electro-optic modulator to be measured.

[0017] In a possible implementation, the optical frequency comb generator includes a mode-locked ultrashort pulse laser or a microresonator.

[0018] In a possible implementation, the system further includes a clock signal generating device;

[0019] The clock signal generating device is used to provide a homologous clock signal to the optical frequency comb generator and the measuring device respectively.

[0020] In the case of adopting the above technical solution, the clock signal generating device can be used to provide a homologous clock signal to the optical frequency comb generator and the measuring device respectively, thereby improving the overall synchronization of the frequency response measurement system and the accuracy of data processing.

[0021] In a possible implementation, the first optoelectronic converter is further used to output the high-frequency electrical comb tooth signal to the measuring device;

[0022] The measuring device is specifically used for:

[0023] Calculating a first frequency response of the optoelectronic converter according to the high-frequency electrical comb tooth signal;

[0024] Calculating a second frequency response according to the electrical signal;

[0025] Calculating the frequency response of the electro-optic modulator to be measured according to the second frequency response and the first frequency response.

[0026] In a possible implementation, the measuring device includes a second optoelectronic converter, an acquisition module and a processing module;

[0027] The second optoelectronic converter is used to convert the modulated optical signal into an electrical signal according to;

[0028] The acquisition module is used to acquire the electrical signal;

[0029] The processing module is used to calculate the frequency response of the electro-optic modulator to be measured according to the acquired electrical signal; the frequency response includes an amplitude-frequency response and a phase-frequency response.

[0030] In a possible implementation, the measuring device is an oscilloscope, and the bandwidth of the oscilloscope matches the bandwidth of the electro-optic modulator to be measured.

[0031] In the case of adopting the above technical solution, the embodiment of the present application can calculate the frequency response of the electro-optic modulator to be measured only by using an oscilloscope. Therefore, the structure is simple and the scene applicability is strong. Moreover, since the bandwidth of the oscilloscope matches the bandwidth of the electro-optic modulator to be measured, the accuracy and effectiveness of the measurement can be ensured.

[0032] In a possible implementation manner, the system further includes a processing device, and the measuring device includes a third photoelectric converter and an acquisition module;

[0033] The third photoelectric converter is used to convert the modulated optical signal into an electrical signal;

[0034] The acquisition module is used to acquire the electrical signal and send the acquired electrical signal to the processing device;

[0035] The processing device is used to calculate the frequency response of the electro-optic modulator to be measured according to the acquired electrical signal; the frequency response includes an amplitude-frequency response and a phase-frequency response.

[0036] In the case of adopting the above technical solution, the frequency response of the electro-optic modulator to be measured is calculated jointly by using the measuring device and the processing device. The photoelectric conversion function and acquisition function of the measuring device are respectively utilized, and the processing function of the processing device is utilized, which can ensure the accuracy of the calculated frequency response of the electro-optic modulator to be measured.

[0037] In a possible implementation manner, the first photoelectric converter is further used to output the high-frequency electrical comb signal to the processing device;

[0038] The processing device is further used to:

[0039] Calculate the first frequency response of the first photoelectric converter according to the high-frequency electrical comb signal;

[0040] Calculate a second frequency response according to the electrical signal;

[0041] Calculate the frequency response of the electro-optic modulator to be measured according to the second frequency response and the first frequency response.

[0042] In a second aspect, the present application provides a frequency response measurement method, which is applied to the frequency response measurement system described in the first aspect.

[0043] The method includes:

[0044] The measuring device acquires a modulated optical signal output by the electro-optic modulator to be measured according to a continuous optical signal and a pulse signal; wherein, adjacent pulses in the pulse signal have a fixed phase relationship;

[0045] The measurement device converts the modulated optical signal into an electrical signal;

[0046] The measurement device calculates the frequency response of the electro-optic modulator to be measured according to the electrical signal; the frequency response includes at least a phase-frequency response.

[0047] In an optional implementation manner, the method further includes:

[0048] The measurement device receives the high-frequency electrical comb signal sent by the first optoelectronic converter in the signal source device;

[0049] The measurement device calculates the first phase-frequency response of the first optoelectronic converter according to the high-frequency electrical comb signal;

[0050] The measurement device calculates a second phase-frequency response according to the electrical signal;

[0051] The measurement device calculates the phase-frequency response of the electro-optic modulator to be measured according to the second phase-frequency response and the first phase-frequency response.

[0052] In a third aspect, the present application provides a frequency response measurement method, which is applied to the frequency response measurement system described in the first aspect. The method includes:

[0053] The processing device receives the electrical signal;

[0054] The processing device calculates the frequency response of the electro-optic modulator to be measured according to the electrical signal; the frequency response includes at least a phase-frequency response.

[0055] In an optional implementation manner, the method further includes:

[0056] The processing device receives the high-frequency electrical comb signal sent by the first optoelectronic converter in the signal source device;

[0057] The processing device calculates the first frequency response of the first optoelectronic converter according to the high-frequency electrical comb signal;

[0058] The processing device calculates a second frequency response according to the electrical signal;

[0059] The processing device calculates the frequency response of the electro-optic modulator to be measured according to the second frequency response and the first frequency response.

[0060] In a fourth aspect, the present application further provides a frequency response measurement device, including a processor, a memory, and a computer program stored on the memory and executable on the processor. When the program is executed by the processor, the method described in any one of the second aspect or the third aspect is implemented.

[0061] In an alternative embodiment, the processor is further configured to:

[0062] Receive a high-frequency electrical comb signal sent by a first photoelectric converter in a signal source device;

[0063] Calculate a first phase-frequency response of the first photoelectric converter according to the high-frequency electrical comb signal;

[0064] Calculate a second phase-frequency response according to the electrical signal;

[0065] Calculate a phase-frequency response of the electro-optic modulator to be measured according to the second phase-frequency response and the first phase-frequency response.

[0066] In a fifth aspect, the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method described in any one of the second aspect is implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0068] Figure 1 Structural schematic of a frequency response measurement system provided by an embodiment of the present application Figure 1 ;

[0069] Figure 2 Structural schematic of a frequency response measurement system provided by an embodiment of the present application Figure 2 ;

[0070] Figure 3 Structural schematic of a frequency response measurement system provided by an embodiment of the present application Figure 3 ;

[0071] Figure 4 Structural layout diagram of a frequency response measurement system provided by an embodiment of the present application;

[0072] Figure 5 Schematic diagram of the frequency response test result of an electro-optic modulator to be measured provided by an embodiment of the present application;

[0073] Figure 6 Schematic diagram of the phase response test result of an electro-optic modulator to be measured provided by an embodiment of the present application;

[0074] Figure 7 Flow chart of a frequency response measurement method provided by an embodiment of the present application Figure 1 ;

[0075] Figure 8 Flow chart of a frequency response measurement method provided by an embodiment of the present applicationFigure 2 ;

[0076] Figure 9 This is a schematic structural diagram of a measuring device provided by an embodiment of the present application. Detailed implementation manners

[0077] Here, exemplary embodiments will be described in detail, and the examples are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0078] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application. It can be understood that the terms "first", "second", etc. used in this application can be used herein to describe various information or data, but these elements are not limited by these terms. These terms are only used to distinguish one piece of information from another. For example, without departing from the scope of this application, the first action information can be called the second action information, and similarly, the second action information can be called the first action information. Both the first action information and the second action information are action information, but they are not the same action information.

[0079] First, the nouns involved in this application are explained:

[0080] Electro-optic modulator: It is a device that uses the electro-optic effect to modulate the characteristics of light waves. The electro-optic effect refers to the phenomenon that the refractive index of certain materials changes under the action of an externally applied electric field.

[0081] Pulse signal: A pulse signal is a periodic waveform signal, usually used in various electronic and communication applications. Pulse signals are characterized by short durations and fast rise / fall times.

[0082] Frequency response: It represents the response characteristics of a system or device to input signals of different frequencies, usually represented by functions of amplitude and phase varying with frequency.

[0083] Amplitude-frequency response: It represents the amplitude response characteristics of a system or device to input signals of different frequencies. Specifically, the amplitude-frequency response indicates how the amplitude of the output signal of the system changes with the frequency of the input signal.

[0084] Phase-frequency response: It represents the phase response characteristics of a system or device to input signals of different frequencies. Specifically, the phase-frequency response indicates how the phase of the system output signal changes with the frequency of the input signal.

[0085] Optical frequency comb signal: It refers to a broadband spectrum composed of a series of equally spaced discrete frequencies, similar to the teeth of a comb, and each frequency component has a stable phase relationship. The frequency interval (i.e., the spacing between the comb teeth) of the optical frequency comb is determined by the repetition frequency of the optical frequency comb generator, usually in the range of MHz (Megahertz) to GHz (Gigahertz).

[0086] Electrical comb tooth signal: An electrical comb tooth signal is an electrical signal that appears as a series of equally spaced frequency lines in the frequency domain, similar to the teeth of a comb.

[0087] Optical frequency comb generator: It is a generator that can generate optical frequency comb signals.

[0088] Opto-electronic converter: An opto-electronic converter is a device or component that converts optical signals into electrical signals; its basic function is to detect incident light and convert it into corresponding current or voltage signals for subsequent signal processing and analysis.

[0089] The technical solution provided in the embodiments of the present application is applied to the frequency response measurement of an electro-optic modulator. The principle of the electro-optic modulator is to utilize the interference of light and achieve intensity modulation of light by controlling the changing electric field. In the actual electro-optic modulation process, it is necessary to measure the frequency response of the electro-optic modulator to perform high-frequency calibration on the electro-optic modulator.

[0090] Currently, the methods for measuring the frequency response of an electro-optic modulator include spectral analysis method and electrical spectral analysis method. Among them, the principle of the spectral analysis method is to utilize the interference of light and achieve intensity modulation of light by controlling the changing electric field, but the spectral analysis method severely depends on the resolution of the spectral analyzer. The electrical spectral analysis method is to apply a single-tone microwave signal or a two-tone microwave signal with frequency scanning to the electro-optic modulator to be measured and analyze the signal recovered from the auxiliary measurement photodetector, thereby measuring the frequency response of the modulator. However, there is no definite phase relationship between the single-tone microwave signal or the two-tone microwave signal. It should be understood that the randomness of the input signal will result in inaccurate phase information in the measurement result, and the phase-frequency response requires accurate phase information. The random input phase will cause errors in phase measurement, thus making it impossible to obtain the accurate phase-frequency response of the optical modulator.

[0091] In view of the above problems, the technical solution proposed in the present application is: The adjacent pulses in the pulse signal provided to the electro-optic modulator have a fixed phase relationship, so as to generate a modulated optical signal by using this pulse signal, and the frequency response of the electro-optic modulator including the phase-frequency response can be accurately calculated based on this modulated optical signal.

[0092] The technical solution proposed in this application can be applied to the frequency response measurement of a broadband electro-optic modulator. Optionally, the broadband electro-optic modulator can be a high-speed electro-optic modulator with a bandwidth of up to 100G.

[0093] The following uses specific embodiments to elaborate in detail on the technical solution of this application and how the technical solution of this application solves the above technical problems. These several specific embodiments can be combined with each other, and concepts or processes that are the same or similar may not be repeated in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0094] Refer to Figure 1 , an embodiment of this application provides a frequency response measurement system for measuring an electro-optic modulator to be measured; the system includes:

[0095] A light source device; the light source device is used to provide a continuous optical signal to the electro-optic modulator to be measured.

[0096] Among them, the light source device can be a DC light source device, which is used to provide a stable and continuous optical signal to the electro-optic modulator to be measured. The optical signal can be monochromatic light or narrow-bandwidth light to ensure the quality and consistency of the signal during modulation.

[0097] A signal source device; the signal source device is used to provide a pulse signal to the electro-optic modulator to be measured; among them, adjacent pulses in the pulse signal have a fixed phase relationship.

[0098] It should be understood that adjacent pulses of the pulse signal have a fixed phase relationship in the frequency domain to ensure that the phase-frequency response of the electro-optic modulator can be accurately calculated using the pulse signal. As a more specific explanation: the fixed phase relationship can ensure that the phase difference between adjacent pulses remains unchanged, so that the phase of the input signal remains consistent and does not randomly change with time as a reference, so that the phase change of the output signal relative to the pulse signal can be accurately measured using the pulse signal. To solve the problem of inaccurate measurement caused by the non-fixed phase of the input pulse signal in the prior art.

[0099] Therefore, using the above pulse signal as the input signal of the electro-optic modulator ensures the stability of the phase of the input signal, thereby reducing the measurement error.

[0100] It should be understood that the phase-frequency response refers to the change of the phase of the output signal with the frequency of the input signal. Since the phase of the input signal in the embodiment of this application is known and stable, the measurement system can more accurately measure the phase response of the electro-optic modulator at different frequencies.

[0101] In this embodiment, the electro-optic modulator is used to output a modulated optical signal according to an optical signal and a pulse signal. Exemplarily, the modulation process includes intensity modulation, phase modulation, and / or frequency modulation.

[0102] For example: The above electro-optic modulator is a Mach-Zehnder Modulator (MZM). In the Mach-Zehnder modulator, the intensity modulation includes: splitting the input optical signal into two paths and propagating in the two optical paths. The pulse signal is applied to one of the optical paths to change the phase of the optical signal on that path. When the two optical signals are recombined in the Mach-Zehnder modulator, due to the change in the phase difference, the intensity of the optical signal changes, realizing intensity modulation. The phase modulation includes: directly changing the phase of the optical signal without affecting the intensity of the optical signal. The frequency modulation includes: realizing modulation by changing the frequency of the optical signal.

[0103] The above frequency response measurement system further includes a measurement device; the measurement device is used to collect the modulated optical signal output by the electro-optic modulator to be measured according to the optical signal and the pulse signal, and convert the modulated optical signal into an electrical signal; the electrical signal is used to calculate the frequency response of the electro-optic modulator to be measured; wherein, the above frequency response at least includes a phase-frequency response.

[0104] In some examples, the above measurement device can be an oscilloscope, or a large-bandwidth vector network analyzer or a high-speed signal analysis instrument, as well as other devices with measurement functions, and no special limitation is made thereto. And the bandwidth of the measurement device matches the bandwidth of the electro-optic modulator to be measured.

[0105] Based on the above description, the embodiment of the present application uses a signal source device to provide a pulse signal with a fixed phase relationship between adjacent pulses to the electro-optic converter to be measured, and the electro-optic converter to be measured modulates the intensity, phase, and / or frequency of the optical signal based on the pulse signal to obtain a modulated optical signal. The measurement device is used to convert the modulated optical signal into an electrical signal, and the electrical signal can be used to calculate the frequency response of the electro-optic modulator to be measured. Since the adjacent pulses in the pulse signal input to the electro-optic converter to be measured have a fixed phase relationship in the frequency domain, it should be understood that when the adjacent pulses of the input signal have a fixed phase relationship in the frequency domain, the consistency of the phase of the input signal can be ensured, and this consistency eliminates the measurement error caused by phase randomness. Therefore, the electrical signal obtained based on the pulse signal can accurately calculate the phase-frequency response of the electro-optic modulator to be measured.

[0106] Furthermore, the frequency response measurement system provided by the embodiments of the present application only needs to provide an optical signal and a pulse signal to the electro-optic modulator to be measured, then collect the modulated optical signal output by the electro-optic modulator according to the optical signal and the pulse signal, and convert it into an electrical signal to calculate the frequency response of the electro-optic modulator to be measured by using the electrical signal, without recovering the signal from the photodetector for auxiliary measurement and performing a complex signal processing process. Therefore, the measurement process complexity of the system provided by the embodiments of the present application is relatively low.

[0107] The above content is used to describe the overall structure and function of the embodiments of the present application. The following part is used to describe each part in detail.

[0108] First, the signal source device is described:

[0109] The signal source device provided by the embodiments of the present application is used to output a pulse signal, and the frequency of the pulse signal can be adapted to the frequency of the electro-optic modulator to be measured. For example, when the electro-optic modulator to be measured is a Mach-Zehnder modulator, the pulse signal is a high-frequency pulse signal. And in order to measure the phase-frequency response of the electro-optic modulator to be measured, the pulse signal has a fixed phase.

[0110] It should be understood that the embodiments of the present application are not only applicable to the above-mentioned Mach-Zehnder modulator, but also applicable to other high-bandwidth electro-optic modulators, such as: phase modulators, in-phase quadrature (IQ) modulators, microring modulators, etc.

[0111] Optionally, the above signal source device may include an optical frequency comb generator and a first optoelectronic converter.

[0112] The optical frequency comb generator is used to generate an optical frequency comb signal.

[0113] In some examples, referring to Figure 2 , the above optical frequency comb generator may include a mode-locked ultrashort pulse laser or a microresonator.

[0114] Among them, the mode-locked ultrashort pulse laser is a mode-locked laser specifically used to generate ultrashort pulses (usually in the femtosecond to picosecond range). These ultrashort pulses correspond to equally spaced frequency components in the frequency domain, forming an optical frequency comb.

[0115] The above mode-locked ultrashort pulse laser includes a femtosecond laser, such as any one of a titanium sapphire laser, an erbium-doped fiber laser, and a dye laser.

[0116] Among them, the microresonator is a microscopic structure for optics, which can achieve strong resonance of light and long-time beam residence in an extremely small volume. The microresonator may include a microtube resonator, a microsphere resonator, or a microring resonator.

[0117] In an embodiment of the present application, the above-mentioned micro-resonator can generate an optical frequency comb signal through a non-linear optical effect.

[0118] The first optoelectronic converter is used to convert the optical frequency comb signal into a high-frequency electrical comb tooth signal and output the high-frequency electrical comb tooth signal to the electro-optic modulator to be measured; wherein, the high-frequency electrical comb tooth signal is the above-mentioned pulse signal.

[0119] Exemplarily, the first optoelectronic converter can be a high-speed photodetector, such as a photodiode or an avalanche photodiode. The high-frequency electrical comb tooth signal obtained after converting the optical frequency comb signal retains the equally-spaced frequency characteristics of the optical frequency comb, and this signal also presents equally-spaced frequency components in the frequency domain.

[0120] Therefore, by inputting the high-frequency electrical comb tooth signal into the electro-optic modulator to be measured, based on the characteristic that the high-frequency electrical comb tooth signal has equally-spaced frequencies, the embodiment of the present application can calculate the phase-frequency response of the electro-optic modulator to be measured at different frequencies.

[0121] Optionally, referring to Figure 2 and Figure 3 , the above-mentioned system may further include a clock signal generating device.

[0122] The clock signal generating device is used to provide a homologous clock signal to the optical frequency comb generator and the measuring device respectively. Based on this, the overall synchronization of the frequency response measurement system and the accuracy of data processing can be improved.

[0123] Based on the above structure, when the embodiment of the present application calculates the frequency response of the electro-optic modulator to be measured using an electrical signal, it is necessary to first measure the frequency response of the first optoelectronic converter to ensure the accuracy of the calculated frequency response of the electro-optic modulator to be measured.

[0124] Based on this, referring to Figure 3 , the first optoelectronic converter is further used to output the high-frequency electrical comb tooth signal to the measuring device.

[0125] The measuring device can calculate the first frequency response (including the first amplitude-frequency response and the first phase-frequency response) of the first optoelectronic converter according to the high-frequency electrical comb tooth signal. Specifically, the optical frequency comb signal is input into the first optoelectronic converter. The first optoelectronic converter is used to convert the optical frequency comb signal into a high-frequency electrical comb tooth signal and output it. Then, the measuring device measures the high-frequency electrical comb tooth signal output by the first optoelectronic converter and records the amplitude and phase information of the output high-frequency electrical comb tooth signal. By comparing the amplitude and phase of the high-frequency electrical comb tooth signal with the known amplitude and phase of the input optical frequency comb signal, the amplitude response and the phase-frequency response of the first optoelectronic converter at each frequency component are calculated, that is, the first amplitude-frequency response and the first phase-frequency response are obtained.

[0126] After that, when adopting, for example, Figure 2The system networking diagram, calculates the second frequency response (including the second amplitude-frequency response and the second phase-frequency response) according to the electrical signal. Specifically, the electrical signal can be input into a measuring device or a processing device to measure the electrical signal and record its amplitude and phase information, and by comparing the amplitude and phase of this signal with the amplitude and phase of the input optical signal of the electro-optic modulator to be measured, the second amplitude-frequency response and the second phase-frequency response are calculated.

[0127] Then, according to the second frequency response and the first frequency response, the frequency response of the electro-optic modulator to be measured is calculated. Specifically, the de-embedding method can be adopted to calculate the frequency response (including the amplitude-frequency response and the phase-frequency response) of the electro-optic modulator to be measured based on the second frequency response and the first frequency response.

[0128] It should be understood that de-embedding is a technique for separating the characteristics of the device to be measured by measuring the system-level response. In the embodiments of the present application, de-embedding is used to determine the frequency response of the electro-optic modulator to be measured. Among them, the first frequency response is the frequency response of the first optoelectronic converter, and the second frequency response is the mixed frequency response of the first optoelectronic converter and the electro-optic modulator to be measured. Among them, the frequency response of the electro-optic modulator to be measured can be characterized as the second frequency response divided by the first frequency response. Refer to Figure 2 and Figure 3 , the above calculation of the first frequency response and the second frequency response can be executed by a measuring device or a processing device. Among them, the processing device can be a host computer.

[0129] In one example, when the calculation of the first frequency response and the second frequency response is executed by the measuring device, the measuring device is specifically used for:

[0130] Calculating the first frequency response of the optoelectronic converter according to the high-frequency electrical comb signal;

[0131] Converting the modulated optical signal into an electrical signal and calculating the second frequency response based on the electrical signal;

[0132] Calculating the frequency response of the electro-optic modulator to be measured according to the first frequency response and the second frequency response. The frequency response of the electro-optic modulator to be measured includes the amplitude-frequency response and the phase-frequency response.

[0133] In another example, when the calculation of the first frequency response and the second frequency response is executed by the processing device, the measuring device can be used for:

[0134] Sending the high-frequency electrical comb signal to the processing device, and the processing device is used to calculate the first frequency response of the optoelectronic converter according to the high-frequency electrical comb signal.

[0135] Convert the modulated optical signal into an electrical signal and send the electrical signal to a processing device, which is used to calculate a second frequency response according to a high-frequency electrical comb signal and calculate the frequency response of the electro-optic modulator under test based on the first frequency response and the second frequency response; wherein the frequency response of the electro-optic modulator under test includes an amplitude-frequency response and a phase-frequency response.

[0136] The measurement device will be described below:

[0137] In one example, the measurement device may include a second optoelectronic converter, an acquisition module, and a processing module.

[0138] Among them, the second optoelectronic converter may be a high-speed photodetector, such as an optical probe, a photodiode, or a photomultiplier tube. This second optoelectronic converter is used to convert the modulated optical signal into an electrical signal.

[0139] The acquisition module is used to acquire the above electrical signal; the acquisition module may include an analog-to-digital converter (ADC) for converting the analog electrical signal into a digital signal for further digital signal processing.

[0140] The processing module is used to calculate the frequency response of the electro-optic modulator under test according to the electrical signal; the frequency response includes an amplitude-frequency response and a phase-frequency response.

[0141] Based on this, the embodiment of the present application can calculate the frequency response of the electro-optic modulator under test according to the modulated optical signal only by using an oscilloscope. Therefore, the structure is simple and applicable to different types of electro-optic modulators. And since the bandwidth of the oscilloscope matches the bandwidth of the electro-optic modulator under test, the accuracy and effectiveness of the measurement can be ensured.

[0142] Optionally, the measurement device may include a third optoelectronic conversion module and an acquisition module, and the above system may further include a processing device (for example: Figure 2 and Figure 3 the host computer in).

[0143] At this time, the optoelectronic conversion module is used to convert the modulated optical signal into an electrical signal;

[0144] The acquisition module is used to acquire the electrical signal;

[0145] The processing device is used to calculate the frequency response of the electro-optic modulator under test according to the electrical signal; the frequency response includes an amplitude-frequency response and a phase-frequency response. The specific calculation method can refer to the above calculation of the frequency response of the electro-optic modulator under test according to the electrical signal, which will not be elaborated here.

[0146] Based on this, in this embodiment, the measurement device and the processing device can be used together to calculate the frequency response of the electro-optic modulator to be measured. By utilizing the photoelectric conversion function and the acquisition function of the measurement device respectively, the accuracy of the calculated frequency response of the electro-optic modulator to be measured can be improved.

[0147] As a specific implementation manner, referring to Figure 4 , the electro-optic modulator to be measured can be a Mach-Zehnder electro-optic modulator with a bandwidth of 40G. The light source device is a laser with a wavelength of 1550nm and an output power of 20mW. The optical signal emitted by the laser is sent into the Mach-Zehnder electro-optic modulator to be measured for modulation. The optical frequency comb generator outputs an optical frequency comb signal with an interval of 99.84MHz to a PD (Photodiode, photoelectric converter) to complete photoelectric conversion, and outputs an electrical comb tooth signal with an interval of 99.84MHz to the RF input port of the Mach-Zehnder electro-optic modulator. The electrical comb tooth signal and the optical carrier are mixed in the Mach-Zehnder electro-optic modulator to output an optical carrier microwave signal to the optical probe of the measurement device for detection, generating an electrical signal. Then, the oscilloscope collects and analyzes the voltage signal, and calculates the amplitude-frequency response and phase-frequency response of the electro-optic modulator in the oscilloscope.

[0148] Referring to Figure 5 , it is a schematic diagram of the frequency response test result of the electro-optic modulator to be measured provided by the embodiment of the present application. Among them, the frequency response curve of the MZM is curve 1, the frequency response curve of the PD is curve 2, and the frequency response curve of the MZM + PD is curve 3. Referring to Figure 6 , it is a schematic diagram of the phase response of the electro-optic modulator to be measured provided by the embodiment of the present application. Among them, the phase response curve of the MZM is curve 4, and the phase response curve of the PD is curve 5.

[0149] Based on this, the embodiment of the present application can not only test the frequency response of the electro-optic modulator to be measured, but also test the phase-frequency response of the electro-optic modulator to be measured.

[0150] Referring to Figure 7 , the embodiment of the present application also provides a frequency response measurement method, which is applied to the frequency response measurement system shown in Figures 1 - 4 , and includes the following steps:

[0151] S701, the measurement device is used to collect the modulated optical signal output by the electro-optic modulator to be measured according to the continuous optical signal and the pulse signal; wherein, adjacent pulses in the pulse signal have a fixed phase relationship.

[0152] This continuous optical signal can ensure the quality and consistency of the signal during the modulation process. The adjacent pulses in the pulse signal have a fixed phase relationship, which is used to ensure that the phase-frequency response of the electro-optic modulator can be accurately calculated using this pulse signal.

[0153] S702, the measuring device converts the modulated optical signal into an electrical signal.

[0154] S703, the measuring device calculates the phase-frequency response of the electro-optic modulator to be measured according to the electrical signal.

[0155] It should be understood that the description of the structure and principle of the frequency response measurement system can refer to the description of the embodiment of the frequency response measurement system above, and will not be repeated here.

[0156] Based on the above description, adjacent pulses in the pulse signal of the embodiment of the present application have a fixed phase relationship in the frequency domain. The electro-optic converter to be measured modulates the intensity, phase, and / or frequency of the continuous optical signal based on the pulse signal to obtain a modulated optical signal. The measuring device is used to convert the modulated optical signal into an electrical signal, and the electrical signal can be used to calculate the frequency response of the electro-optic modulator to be measured. Since adjacent pulses in the pulse signal input to the electro-optic converter to be measured have a fixed phase relationship in the frequency domain, it should be understood that when adjacent pulses of the input signal have a fixed phase relationship in the frequency domain, the consistency of the phase of the input signal can be ensured, and this consistency eliminates the measurement error caused by phase randomness. Therefore, the phase-frequency response of the electro-optic modulator to be measured can be accurately calculated based on the electrical signal obtained from the pulse signal.

[0157] Furthermore, the method provided by the embodiment of the present application only needs to provide an optical signal and a pulse signal to the electro-optic modulator to be measured, then collect the modulated optical signal output by the electro-optic modulator according to the optical signal and the pulse signal, and convert it into an electrical signal to calculate the frequency response of the electro-optic modulator to be measured using the electrical signal. In the prior art, the electrical spectrum analysis method needs to recover the signal from the auxiliary measurement photodetector and perform phase-frequency calculation based on the recovered signal. It should be further understood that recovering the signal from the photodetector requires a complex signal processing process, while the present application omits the process of recovering the signal. Therefore, the measurement process complexity of the system provided by the embodiment of the present application is relatively low.

[0158] In some examples, the above method further includes:

[0159] The measuring device receives the high-frequency electrical comb signal sent by the first photoelectric converter in the signal source device;

[0160] The measuring device calculates the first phase-frequency response of the first photoelectric converter according to the high-frequency electrical comb signal;

[0161] The measuring device calculates the second phase-frequency response according to the electrical signal;

[0162] The measuring device calculates the phase-frequency response of the electro-optic modulator to be measured according to the second phase-frequency response and the first phase-frequency response.

[0163] Refer to Figure 8, embodiments of the present application also provide a frequency response measurement method, which is applied to Figures 1 - 4 the frequency response measurement system shown in the figure, and includes the following steps:

[0164] S801, the processing device receives the electrical signal.

[0165] S802, the processing device calculates the frequency response of the electro-optic modulator to be measured according to the electrical signal; the frequency response includes at least the phase-frequency response.

[0166] The electrical signal received by the processing device in the embodiments of the present application is obtained by converting the modulated optical signal, and the modulated optical signal is obtained by the electro-optic modulator to be measured according to the continuous optical signal and the pulse signal. Among them, adjacent pulses in the pulse signal have a fixed phase relationship in the frequency domain. Specifically, the electro-optic converter to be measured modulates the intensity, phase, and / or frequency of the continuous optical signal based on the pulse signal to obtain the modulated optical signal. The measuring device is used to convert the modulated optical signal into an electrical signal, and the electrical signal can be used to calculate the frequency response of the electro-optic modulator to be measured. Since adjacent pulses in the pulse signal input to the electro-optic converter to be measured have a fixed phase relationship in the frequency domain, it should be understood that when adjacent pulses of the input signal have a fixed phase relationship in the frequency domain, the consistency of the phase of the input signal can be ensured, and this consistency eliminates the measurement error caused by phase randomness. Therefore, the electrical signal obtained based on the pulse signal can accurately calculate the phase-frequency response of the electro-optic modulator to be measured.

[0167] Furthermore, the method provided in the embodiments of the present application only needs to provide an optical signal and a pulse signal to the electro-optic modulator to be measured, then collect the modulated optical signal output by the electro-optic modulator according to the optical signal and the pulse signal, and convert it into an electrical signal to calculate the frequency response of the electro-optic modulator to be measured using the electrical signal. In the prior art, the electrical spectrum analysis method needs to recover the signal from the auxiliary measurement photodetector and perform phase-frequency calculation based on the recovered signal. It should be further understood that recovering the signal from the photodetector requires a complex signal processing process, while the present application omits the process of recovering the signal. Therefore, the measurement process complexity of the system provided in the embodiments of the present application is relatively low.

[0168] In some examples, the above method further includes:

[0169] The processing device receives the high-frequency electrical comb signal sent by the first photoelectric converter in the signal source device;

[0170] The processing device calculates the first frequency response of the first photoelectric converter according to the high-frequency electrical comb signal;

[0171] The processing device calculates the second frequency response according to the electrical signal;

[0172] The processing device calculates the frequency response of the electro-optical modulator under test according to the second frequency response and the first frequency response.

[0173] This application also provides a measurement device. Figure 9 It is a schematic structural diagram of the measurement device provided in the embodiments of this application. As Figure 9 shown, the measurement device may include: a transceiver 121, a processor 122, and a memory 123.

[0174] The processor 122 executes the computer-executable instructions stored in the memory, so that the processor 122 performs the above Figure 7 or Figure 8 operations performed by the measurement device or the processing device in the frequency response measurement method embodiments.

[0175] The processor 122 may be a general-purpose processor, including a central processing unit CPU, a network processor (NP), etc.; it may also be a digital signal processor DSP, an application-specific integrated circuit ASIC, a field-programmable gate array FPGA, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0176] The memory 123 is connected to the processor 122 through a system bus and completes communication therebetween. The memory 123 is used to store computer program instructions.

[0177] The transceiver 121 may be used to obtain the task to be run and the configuration information of the task to be run.

[0178] The system bus may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The system bus may be divided into an address bus, a data bus, a control bus, etc. For the sake of simplicity, only a thick line is shown in the figure, but it does not mean that there is only one bus or one type of bus. The transceiver is used to implement communication between the database access device and other computers (such as clients, read-write libraries, and read-only libraries). The memory may include a random access memory (RAM), and may also include a non-volatile memory.

[0179] The embodiments of this application also provide a chip for running instructions. The chip is used to execute the operations performed by the measurement device or the processing device in the above Figure 7 or Figure 8 frequency response measurement method embodiments.

[0180] An embodiment of the present application also provides a computer-readable storage medium, in which computer instructions are stored. When the computer instructions run on a computer, the computer is caused to execute the operations performed by the measuring device or the processing device in the above Figure 7 or Figure 8 frequency response measurement method embodiments.

[0181] An embodiment of the present application also provides a computer program product, which includes a computer program stored in a computer-readable storage medium. At least one processor can read the computer program from the computer-readable storage medium, and when at least one processor executes the computer program, the operations performed by the measuring device or the processing device in the above Figure 7 or Figure 8 frequency response measurement method embodiments can be implemented.

[0182] In several embodiments provided by the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of modules is only a logical function division. In actual implementation, there may be other division methods. For example, multiple modules can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of devices or modules can be in electrical, mechanical or other forms.

[0183] 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 units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to implement the solution of this embodiment.

[0184] In addition, in each embodiment of the present application, the functional modules can be integrated in a processing unit, or each module can exist physically alone, or two or more modules can be integrated in one unit. The unit formed by the above modules can be implemented in the form of hardware, or in the form of a hardware plus software functional unit.

[0185] The above integrated modules implemented in the form of software functional modules can be stored in a computer-readable storage medium. The above software functional modules are stored in a storage medium, including several instructions to cause a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to execute some steps of the methods in each embodiment of the present application.

[0186] It should be understood that the above-mentioned processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the method disclosed in combination with the invention can be directly embodied as being completed by a hardware processor, or can be completed by a combination of hardware and software modules in the processor.

[0187] The memory may include high-speed RAM memory, and may also include non-volatile storage NVM, such as at least one disk memory, and may also be a USB flash drive, a mobile hard disk, a read-only memory, a magnetic disk, or an optical disc, etc.

[0188] The bus may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of convenience in representation, the bus in the drawings of this application is not limited to only one bus or one type of bus.

[0189] The above-mentioned storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic memory, flash memory, magnetic disks or optical discs. The storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0190] An exemplary storage medium is coupled to the processor, enabling the processor to read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an Application Specific Integrated Circuit (ASIC). Of course, the processor and the storage medium can also exist as discrete components in an electronic control unit or a master control device.

Claims

1. A frequency response measurement system, characterized in that, For measuring an electro-optic modulator to be measured; the system includes: A light source device for providing a continuous optical signal to the electro-optic modulator to be measured; A signal source device for providing a pulse signal to the electro-optic modulator to be measured, wherein adjacent pulses in the pulse signal have a fixed phase relationship; A measurement device for collecting a modulated optical signal output by the electro-optic modulator to be measured according to the optical signal and the pulse signal, and converting the modulated optical signal into an electrical signal, and the electrical signal is used to calculate the frequency response of the electro-optic modulator to be measured, and the frequency response at least includes a phase-frequency response; The pulse signal is a high-frequency electrical comb signal; the signal source device includes an optical frequency comb generator and a first optoelectronic converter; The optical frequency comb generator is used to generate an optical frequency comb signal; The first optoelectronic converter is used to convert the optical frequency comb signal into a high-frequency electrical comb signal and output the high-frequency electrical comb signal to the electro-optic modulator to be measured.

2. The system according to claim 1, characterized in that, The optical frequency comb generator includes a mode-locked ultrashort pulse laser or a microresonator.

3. The system according to claim 1, wherein The system further includes a clock signal generating device; The clock signal generating device is used to provide a homologous clock signal to the optical frequency comb generator and the measurement device respectively.

4. The system according to any one of claims 1-3, characterized in that, The first optoelectronic converter is further used to output the high-frequency electrical comb signal to the measurement device; The measurement device is specifically used for: Calculating a first frequency response of the first optoelectronic converter according to the high-frequency electrical comb signal; Calculating a second frequency response according to the electrical signal; Calculating the frequency response of the electro-optic modulator to be measured according to the second frequency response and the first frequency response.

5. The system according to claim 4, wherein The measurement device includes a second optoelectronic converter, an acquisition module and a processing module; The second optoelectronic converter is used to convert the modulated optical signal into an electrical signal according to; The acquisition module is used to acquire the electrical signal; The processing module is used to calculate the frequency response of the electro-optic modulator to be measured according to the acquired electrical signal; the frequency response includes an amplitude-frequency response and a phase-frequency response.

6. The system according to claim 5, wherein The measurement device is an oscilloscope, and the bandwidth of the oscilloscope matches the bandwidth of the electro-optic modulator to be measured.

7. The system according to any one of claims 1 to 3, characterized in that, The system further includes a processing device, and the measurement device includes a third optoelectronic converter and an acquisition module; The third optoelectronic converter is used to convert the modulated optical signal into an electrical signal; The acquisition module is used to acquire the electrical signal and send the acquired electrical signal to the processing device; The processing device is used to calculate the frequency response of the electro-optic modulator to be measured according to the acquired electrical signal, and the frequency response includes an amplitude-frequency response and a phase-frequency response.

8. The system according to claim 7, wherein The first optoelectronic converter is further used to output the high-frequency electrical comb signal to the processing device; The processing device is further used for: Calculating a first frequency response of the first optoelectronic converter according to the high-frequency electrical comb signal; Calculating a second frequency response according to the electrical signal; Calculating the frequency response of the electro-optic modulator to be measured according to the second frequency response and the first frequency response.

9. A frequency response measurement method, characterized in that, Applied to the frequency response measurement system according to any one of claims 1-5, the method includes: The measuring device collects the modulated optical signal output by the electro-optic modulator under test according to the continuous optical signal and the pulse signal, wherein adjacent pulses in the pulse signal have a fixed phase relationship; The measuring device converts the modulated optical signal into an electrical signal; The measuring device calculates the frequency response of the electro-optic modulator under test according to the electrical signal, and the frequency response includes at least the phase-frequency response.

10. The method according to claim 9, wherein The method further includes: The measuring device receives the high-frequency electrical comb signal sent by the first optoelectronic converter in the signal source device; The measuring device calculates the first phase-frequency response of the first optoelectronic converter according to the high-frequency electrical comb signal; The measuring device calculates the second phase-frequency response according to the electrical signal; The measuring device calculates the phase-frequency response of the electro-optic modulator under test according to the second phase-frequency response and the first phase-frequency response.

11. A frequency response measurement method, characterized in that, Applied to the frequency response measurement system described in claim 7 or 8, the method includes: The processing device receives the electrical signal; The processing device calculates the frequency response of the electro-optic modulator under test according to the electrical signal, and the frequency response includes at least the phase-frequency response.

12. The method according to claim 11, wherein The method further includes: The processing device receives the high-frequency electrical comb signal sent by the first optoelectronic converter in the signal source device; The processing device calculates the first frequency response of the first optoelectronic converter according to the high-frequency electrical comb signal; The processing device calculates the second frequency response according to the electrical signal; The processing device calculates the frequency response of the electro-optic modulator under test according to the second frequency response and the first frequency response.

13. A measuring device, characterized in that, Comprising a processor, a memory, and a computer program stored on the memory and executable on the processor, the program, when executed by the processor, implements the method described in claim 9 or 10, or the method described in claim 11 or 12.

14. The device according to claim 13, characterized in that, The processor is further configured to: Receive the high-frequency electrical comb signal sent by the first optoelectronic converter in the signal source device; Calculate the first phase-frequency response of the first optoelectronic converter according to the high-frequency electrical comb signal; Calculate the second phase-frequency response according to the electrical signal; Calculate the phase-frequency response of the electro-optic modulator under test according to the second phase-frequency response and the first phase-frequency response.

15. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium, and when the computer program is executed by the processor, it implements the method described in claim 9 or 10, or the method described in claim 11 or 12.

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