Frequency response measurement method, device and system and storage medium

Abstract

The invention provides a frequency response measurement method, device and system and a storage medium, and relates to the technical field of frequency response measurement. The frequency response measurement system comprises: a light source device; the light source device is used for providing continuous light signals for the electro-optical modulator to be tested; a signal source device; the signal source device is used for providing pulse signals for the electro-optical modulator to be tested; wherein adjacent pulses in the pulse signal have a fixed phase relationship; a measuring device; the measuring device is used for collecting a modulated light signal output by the electro-optical modulator to be measured according to the light signal and the pulse signal, and converting the modulated light signal into an electric signal; the electric signal is used for calculating the frequency response of the electro-optical modulator to be measured; the frequency response includes at least a phase-frequency response. According to the technical scheme, the complexity of the measurement process is low, and the phase-frequency response of the electro-optical modulator can be measured.

Description

Technical Field

[0001] The present application relates to the technical field of frequency response measurement, and in particular 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 the optical fiber communication system, is rapidly iterating towards high speed, large capacity and long distance. In high-frequency scenarios, traditional electrical interconnection technology is limited by physical mechanisms and structural processes such as skin effect, dielectric loss, parasitic parameters and electromagnetic radiation, and the communication distance and communication rate can no longer meet the interconnection needs.

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

[0004] The frequency response of the large-bandwidth electro-optic modulator used in high-speed communication systems directly affects the signal quality. The amplitude-frequency response determines the signal amplitude fidelity. Its unevenness will cause the attenuation of high-frequency components and time-domain pulse broadening, triggering inter-symbol interference (ISI), and worsening the bit error rate to an unacceptable level. The phase-frequency response determines the phase transmission linearity. The group delay distortion (GVD) introduced by its nonlinearity will accumulate phase noise and directly destroy the carrier phase estimation of coherent communication.

[0005] At present, the methods for measuring the frequency response of electro-optic modulators include spectral analysis and electrical spectrum analysis. The spectral analysis method realizes direct measurement in the optical domain through an optical spectrum analyzer (OSA) or an optical vector analyzer (OVA). However, the traditional optical spectrum analyzer is limited by the spectral resolution, and its starting measurement frequency and measurement resolution are usually limited to about 2.5GHz (i.e., 0.02nm@1550nm), which is difficult to meet the needs of high-frequency precision measurement. Although the optical vector analyzer can directly obtain the amplitude and phase response, commercial instruments are scarce and expensive (more than one million yuan per unit), and are not of general use value. The electrical spectrum analysis method uses a microwave network analyzer to apply a frequency-scanned single-tone microwave signal 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 deterministic "frequency-phase" association, and cannot measure the phase frequency response of the electro-optic modulator. In addition, the frequency response calibration of the auxiliary photodetector introduces error accumulation such as cable loss and device parasitic parameters in the high frequency band, which reduces 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, which are used to provide a technical solution with low measurement process complexity and capable of accurately measuring the phase-frequency response of an electro-optical modulator.

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

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

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

[0010] A measuring device; the measuring device is used to collect the modulated optical signal output by the electro-optical modulator to be tested 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-optical modulator to be tested; the frequency response at least includes a phase-frequency response.

[0011] In the case of adopting the above technical solution, the embodiment of the present application utilizes the adjacent pulses in the pulse signal provided by the signal source device to the electro-optical converter to be tested to have a fixed phase relationship in the frequency domain, and the electro-optical converter to be tested modulates the intensity, phase and / or frequency of the 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, which can be used to calculate the frequency response of the electro-optical modulator to be tested. Since the adjacent pulses in the pulse signal input to the electro-optical converter to be tested 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. 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-optical modulator to be tested.

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

[0013] In a possible implementation, the pulse signal is a high-frequency electric comb 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 photoelectric converter is used to convert the optical frequency comb signal into a high-frequency electric comb signal, and output the high-frequency electric comb signal to the electro-optical modulator to be tested.

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

[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] When the above technical solution is adopted, a clock signal generating device can be used to provide homologous clock signals 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 photoelectric converter is further used to output the high-frequency electric comb signal to the measuring device;

[0022] The measuring device is specifically used for:

[0023] Calculating a first frequency response of the photoelectric converter according to the high-frequency electric comb signal;

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

[0025] The frequency response of the electro-optic modulator to be tested is calculated according to the second frequency response and the first frequency response.

[0026] In a possible implementation, the measuring device includes a second photoelectric converter, a collection module and a processing module;

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

[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 tested according to the collected electrical signal; the frequency response includes an amplitude-frequency response and a phase-frequency response.

[0030] In a possible implementation manner, 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 tested according to the modulated optical signal using only an oscilloscope, so the structure is simple and the scene applicability is strong. And because the bandwidth of the oscilloscope matches the bandwidth of the electro-optic modulator to be tested, the accuracy and effectiveness of the measurement can be ensured.

[0032] In a possible implementation, the system further includes a processing device, and the measuring device includes a third photoelectric converter and a collection 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 tested according to the collected electrical signal; the frequency response includes an amplitude-frequency response and a phase-frequency response.

[0036] When the above technical solution is adopted, the frequency response of the electro-optic modulator to be tested is calculated by using a measuring device and a processing device together, and the photoelectric conversion function and the acquisition function of the measuring device and the processing function of the processing device are respectively utilized, so as to ensure the accuracy of the calculated frequency response of the electro-optic modulator to be tested.

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

[0038] The processing device is also used for:

[0039] Calculating a first frequency response of the first photoelectric converter according to the high-frequency electric comb signal;

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

[0041] The frequency response of the electro-optic modulator to be tested is calculated 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 comprises:

[0044] The measuring device collects a modulated optical signal output by the electro-optical 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 measuring device converts the modulated optical signal into an electrical signal;

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

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

[0048] The measuring device receives the high-frequency electric comb signal sent by the first photoelectric converter in the signal source device;

[0049] The measuring device calculates a first phase-frequency response of the first photoelectric converter according to the high-frequency electric comb signal;

[0050] The measuring device calculates a second phase-frequency response based on the electrical signal;

[0051] 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.

[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 comprises:

[0053] The processing device receives the electrical signal;

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

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

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

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

[0058] The processing device calculates a second frequency response based on the electrical signal;

[0059] The processing device calculates the frequency response of the electro-optic modulator to be tested 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, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the program, when executed by the processor, implements the method described in any one of the second aspect or the third aspect.

[0061] In an optional implementation, the processor is further configured to:

[0062] receiving a high-frequency electric 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 electric comb signal;

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

[0065] The phase-frequency response of the electro-optic modulator to be tested is calculated 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, and when the computer program is executed by a processor, the method described in any one of the second aspects is implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0068] Figure 1 A schematic diagram of a frequency response measurement system provided in an embodiment of the present application Figure 1 ;

[0069] Figure 2 A schematic diagram of a frequency response measurement system provided in an embodiment of the present application Figure 2 ;

[0070] Figure 3 A schematic diagram of a frequency response measurement system provided in an embodiment of the present application Figure 3 ;

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

[0072] Figure 5 A schematic diagram of a frequency response test result of an electro-optic modulator to be tested provided in an embodiment of the present application;

[0073] Figure 6 A schematic diagram of a phase response test result of an electro-optic modulator to be tested provided in an embodiment of the present application;

[0074] Figure 7 A frequency response measurement method process provided in the embodiment of the present application Figure 1 ;

[0075] Figure 8 A frequency response measurement method process provided in the embodiment of the present application Figure 2 ;

[0076] Fig. 9 A schematic diagram of the structure of a measuring device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0077] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, 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 those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. It is understood that the terms "first", "second", etc. used in the present application can be used to describe various information or data in this article, but these elements are not limited by these terms. These terms are only used to distinguish the first information from another information. For example, without departing from the scope of the present application, the first action information can be referred to as the second action information, and similarly, the second action information can be referred to as 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 terms involved in this application are explained:

[0080] Electro-optic modulator: A device that uses the electro-optic effect to modulate the properties of light waves. The electro-optic effect refers to the phenomenon that the refractive index of certain materials changes under the influence of an external electric field.

[0081] Pulse signal: A pulse signal is a periodic waveform signal that is commonly used in various electronic and communication applications. Pulse signals are characterized by short duration and fast rise / fall time.

[0082] Frequency response: It refers to the reaction characteristics of a system or device to input signals of different frequencies, usually expressed as a function of amplitude and phase varying with frequency.

[0083] Amplitude-frequency response: It indicates 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 system output signal changes with the change of the input signal frequency.

[0084] Phase-frequency response: It indicates 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 change of the input signal frequency.

[0085] Optical frequency comb signal: 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 of the optical frequency comb (i.e., the spacing between the comb teeth) is determined by the repetition frequency of the optical frequency comb generator, usually in the MHz (Megahertz) to GHz (Gigahertz) range.

[0086] Electric comb signal: An electric comb 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: a generator that can generate optical frequency comb signals.

[0088] Photoelectric converter: A photoelectric 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 embodiment of the present application is applied to the frequency response measurement of the electro-optic modulator. The principle of the electro-optic modulator is to use the interference of light to achieve the 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] At present, the methods for measuring the frequency response of electro-optic modulators include spectral analysis and electrical spectral analysis. Among them, the principle of spectral analysis is to use the interference of light to achieve light intensity modulation by controlling the changing electric field, but spectral analysis is heavily dependent on the resolution of the spectrometer. The electrical spectral analysis method is to apply a frequency-scanned single-tone microwave signal or a dual-tone microwave signal to the electro-optical modulator under test, and analyze the signal recovered from the auxiliary measurement photodetector to measure the frequency response of the modulator. However, single-tone microwave signals or dual-tone microwave signals have no definite phase relationship. It should be understood that the randomness of the input signal will lead to inaccurate phase information in the measurement results, and the phase-frequency response requires precise phase information. The random input phase will cause errors in phase measurement, and it is impossible to obtain the accurate phase-frequency response of the optical modulator.

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

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

[0093] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0094] Reference Figure 1 The embodiment of the present application provides a frequency response measurement system for measuring an electro-optical modulator to be measured; the system comprises:

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

[0096] The light source device may be a direct current light source device, which is used to provide a stable and continuous optical signal to the electro-optic modulator to be tested. The optical signal may be monochromatic light or narrow bandwidth light to ensure the quality and consistency of the signal during the modulation process.

[0097] A signal source device; the signal source device is used to provide a pulse signal to the electro-optical modulator to be tested; wherein 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, thereby keeping the phase of the input signal consistent and not randomly changing the reference over time, so that the pulse signal can be used to accurately measure the phase change of the output signal relative to the pulse signal. This solves 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 phase stability of the input signal, thereby reducing the measurement error.

[0100] It should be understood that the phase-frequency response refers to the change in the phase of the output signal as the frequency of the input signal changes. Since the phase of the input signal in the embodiment of the present 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 the optical signal and the pulse signal. Exemplarily, the modulation process includes intensity modulation, phase modulation and / or frequency modulation.

[0102] For example, the electro-optic modulator mentioned above is a Mach-Zehnder Modulator (MZM). In a Mach-Zehnder modulator, intensity modulation includes: dividing the input optical signal into two paths and propagating in two optical paths. A 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, the intensity of the optical signal changes due to the change in phase difference, thereby achieving intensity modulation. Phase modulation includes: directly changing the phase of the optical signal without affecting the intensity of the optical signal. Frequency modulation includes: achieving modulation by changing the frequency of the optical signal.

[0103] The above-mentioned frequency response measurement system also includes a measuring device; the measuring device is used to collect the modulated optical signal output by the electro-optical modulator to be tested 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-optical modulator to be tested; wherein the above-mentioned frequency response at least includes a phase-frequency response.

[0104] In some examples, the measuring device may be an oscilloscope, a large-bandwidth vector network analyzer or a high-speed signal analyzer, or other equipment with a measuring function, without any particular limitation, and the bandwidth of the measuring 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 in which adjacent pulses have a fixed phase relationship to the electro-optical converter to be tested. The electro-optical converter to be tested modulates the intensity, phase and / or frequency of the 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, which can be used to calculate the frequency response of the electro-optical modulator to be tested. Since adjacent pulses in the pulse signal input to the electro-optical converter to be tested 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 electrical signal obtained based on the pulse signal can accurately calculate the phase-frequency response of the electro-optical modulator to be tested.

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

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

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

[0109] The signal source device provided in the embodiment of the present application is used to output a pulse signal, the frequency of which can be adapted to the frequency of the electro-optic modulator to be tested. For example, when the electro-optic modulator to be tested is a Mach-Zehnder modulator, the pulse signal is a high-frequency pulse signal. In order to measure the phase-frequency response of the electro-optic modulator to be tested, 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 to other high-bandwidth electro-optical modulators, such as: phase modulator, in-phase quadrature (IQ) modulator, micro-ring modulator, etc.

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

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

[0113] In some examples, reference Figure 2 The optical frequency comb generator may include a mode-locked ultrashort pulse laser or a micro-resonant cavity.

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

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

[0116] Among them, a micro-resonant cavity is a tiny structure used in optics, which can achieve strong resonance of light and long-term light beam residence in a very small volume. The micro-resonant cavity can include a micro-tube resonant cavity, a micro-sphere resonant cavity or a micro-ring resonant cavity.

[0117] In the embodiment of the present application, the above-mentioned micro-resonant cavity can generate an optical frequency comb signal through nonlinear optical effects.

[0118] The first photoelectric converter is used to convert the optical frequency comb signal into a high-frequency electric comb signal, and output the high-frequency electric comb signal to the electro-optical modulator to be tested; wherein the high-frequency electric comb signal is the above-mentioned pulse signal.

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

[0120] Therefore, a high-frequency electric comb signal is input to the electro-optic modulator to be tested. Based on the characteristic that the high-frequency electric comb signal has equally spaced frequencies, the embodiment of the present application can calculate the phase-frequency response of the electro-optic modulator to be tested at different frequencies.

[0121] Optional, see Figure 2 and Figure 3 , the above system may further include a clock signal generating device.

[0122] The clock signal generating device is used to provide the same source 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, the present application is implemented to calculate the frequency response of the electro-optic modulator to be tested using an electrical signal. It is necessary to first measure the frequency response of the first photoelectric converter to ensure the accuracy of the calculated frequency response of the electro-optic modulator to be tested.

[0124] Based on this, refer to Figure 3 The first photoelectric converter is also used to output the high-frequency electric comb 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 photoelectric converter according to the high-frequency electric comb signal. Specifically, the optical frequency comb signal is input into the first photoelectric converter. The first photoelectric converter is used to convert the optical frequency comb signal into a high-frequency electric comb signal and output it. Then, the measuring device is used to measure the high-frequency electric comb signal output by the first photoelectric converter, and the amplitude and phase information of the output high-frequency electric comb signal is recorded. By comparing the amplitude and phase of the high-frequency electric comb signal with the known amplitude and phase of the input optical frequency comb signal, the amplitude response and phase-frequency response of the first photoelectric converter at each frequency component are calculated, and the first amplitude-frequency response and the first phase-frequency response are obtained.

[0126] Afterwards, using Figure 2The system networking diagram is shown, and the second frequency response (including the second amplitude-frequency response and the second phase-frequency response) is calculated 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 its amplitude and phase information can be recorded. The second amplitude-frequency response and the second phase-frequency response can be calculated by comparing the amplitude and phase of the signal with the amplitude and phase of the input optical signal of the electro-optical modulator to be measured.

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

[0128] It should be understood that de-embedding is a technique for separating the characteristics of the device under test by measuring the system-level response. In the embodiment of the present application, de-embedding is used to determine the frequency response of the electro-optic modulator under test. The first frequency response is the frequency response of the first photoelectric converter, and the second frequency response is the mixed frequency response of the first photoelectric converter and the electro-optic modulator under test. The frequency response of the electro-optic modulator under test can be characterized as the second frequency response divided by the first frequency response. Figure 2 and Figure 3 The calculation of the first frequency response and the second frequency response can be performed by a measuring device or a processing device, wherein 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 performed by a measuring device, the measuring device is specifically configured to:

[0130] Calculating a first frequency response of the photoelectric converter according to the high-frequency electric comb signal;

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

[0132] The frequency response of the electro-optic modulator to be tested is calculated according to the first frequency response and the second frequency response, wherein the frequency response of the electro-optic modulator to be tested includes an amplitude-frequency response and a phase-frequency response.

[0133] In another example, when calculating the first frequency response and the second frequency response is performed by the processing device, the measuring device may be configured to:

[0134] The high-frequency electric comb signal is sent to a processing device, and the processing device is used to calculate a first frequency response of the photoelectric converter according to the high-frequency electric comb signal.

[0135] The modulated optical signal is converted into an electrical signal, and the electrical signal is sent to a processing device, which is used to calculate a second frequency response according to the high-frequency electric comb signal, and calculate the frequency response of the electro-optical modulator to be tested according to the first frequency response and the second frequency response; wherein the frequency response of the electro-optical modulator to be tested includes an amplitude-frequency response and a phase-frequency response.

[0136] The measurement setup is described below:

[0137] In one example, the measuring device may include a second photoelectric converter, a collection module, and a processing module.

[0138] The second photoelectric converter can be a high-speed photoelectric detector, such as an optical probe, a photodiode or a photomultiplier tube. The second photoelectric converter is used to convert the modulated optical signal into an electrical signal.

[0139] The acquisition module is used to acquire the above-mentioned 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 to be tested according to the electrical signal; the frequency response includes amplitude-frequency response and phase-frequency response.

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

[0142] Optionally, the measuring device may include a third photoelectric conversion module and a collection module, and the above system may also include a processing device (for example: Figure 2 and Figure 3 host computer in the system).

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

[0144] The acquisition module is used to collect electrical signals;

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

[0146] Based on this, this embodiment can use the measuring device and the processing device to jointly calculate the frequency response of the electro-optic modulator to be tested, respectively utilizing the photoelectric conversion function and the acquisition function of the measuring device, which can improve the accuracy of the calculated frequency response of the electro-optic modulator to be tested.

[0147] As a specific implementation method, refer to Figure 4 The electro-optic modulator to be tested 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 to the Mach-Zehnder electro-optic modulator to be tested for modulation. The optical comb generator outputs an optical frequency comb signal with an interval of 99.84MHz to the PD (Photodiode, photoelectric converter) to complete the photoelectric conversion, and outputs an electric comb signal with an interval of 99.84MHz to the RF input port of the Mach-Zehnder electro-optic modulator. The electric comb signal and the optical carrier are mixed in the Mach-Zehnder electro-optic modulator to output the optical carrier microwave signal to the optical probe of the measuring device for detection, and the generated electrical signal is then collected and analyzed by the oscilloscope, and the amplitude-frequency response and phase-frequency response of the electro-optic modulator are calculated in the oscilloscope.

[0148] Reference Figure 5 , is a schematic diagram of the frequency response test results of the electro-optic modulator to be tested provided in an embodiment of the present application, wherein the frequency response curve of MZM is curve 1, the frequency response curve of PD is curve 2, and the frequency response curve of MZM+PD is curve 3. Figure 6 , is a schematic diagram of the phase response of the electro-optic modulator to be tested provided in an embodiment of the present application, wherein 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 embodiments of the present application can test both the frequency response of the electro-optic modulator to be tested and the phase-frequency response of the electro-optic modulator to be tested.

[0150] Reference Figure 7 The present application also provides a frequency response measurement method, which is applied to Figure 1-Figure 4 The frequency response measurement system shown includes the following steps:

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

[0152] The continuous optical signal can ensure the quality and consistency of the signal during the modulation process. 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 the 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 structure and principle description of the frequency response measurement system can refer to the above description of the frequency response measurement system embodiment, which will not be repeated here.

[0156] Based on the above description, the adjacent pulses in the pulse signal of the embodiment of the present application have a fixed phase relationship in the frequency domain, and the electro-optical converter to be tested 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, which can be used to calculate the frequency response of the electro-optical modulator to be tested. Since the adjacent pulses in the pulse signal input to the electro-optical converter to be tested 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. 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-optical modulator to be tested.

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

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

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

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

[0161] The measuring device calculates a second phase-frequency response based on 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] Reference Figure 8The present application also provides a frequency response measurement method, which is applied to Figure 1-Figure 4 The frequency response measurement system shown includes the following steps:

[0164] S801: The processing device receives the electrical signal.

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

[0166] The electrical signal received by the processing device of the embodiment of the present application is obtained by converting the modulated optical signal, and the modulated optical signal is obtained by the electro-optical modulator to be tested based on the continuous optical signal and the pulse signal. Among them, the adjacent pulses in the pulse signal have a fixed phase relationship in the frequency domain. Specifically, the electro-optical converter to be tested 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-optical modulator to be tested. Since the adjacent pulses in the pulse signal input to the electro-optical converter to be tested 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. This consistency eliminates the measurement error caused by the randomness of the phase. Therefore, the electrical signal obtained based on the pulse signal can accurately calculate the phase-frequency response of the electro-optical modulator to be tested.

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

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

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

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

[0171] The processing device calculates a second frequency response based on the electrical signal;

[0172] The processing device calculates the frequency response of the electro-optic modulator to be tested according to the second frequency response and the first frequency response.

[0173] The present application also provides a measuring device, Fig. 9 This is a schematic diagram of the structure of the measurement device provided in the embodiment of the present application. Fig. 9 As shown, the measuring 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 a measuring device or a processing device in the frequency response measurement method embodiment.

[0175] The processor 122 can be a general-purpose processor, including a central processing unit CPU, a network processor (NP), etc.; it can 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 via a system bus and completes communication between them. The memory 123 is used to store computer program instructions.

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

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

[0179] The present application also provides a chip for executing instructions. Figure 7 or Figure 8 The operations performed by the measuring device or the processing device in the frequency response measurement method embodiment.

[0180] The embodiment of the present application also provides a computer-readable storage medium, in which a computer instruction is stored. When the computer instruction is executed on a computer, the computer executes the above Figure 7 or Figure 8 The operations performed by the measuring device or the processing device in the frequency response measurement method embodiment.

[0181] 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. When the at least one processor executes the computer program, the above-mentioned Figure 7 or Figure 8 The operations performed by the measuring device or the processing device in the frequency response measurement method embodiment.

[0182] In the several embodiments provided in 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 only schematic, for example, the division of modules is only a logical function division, and there may be other division methods in actual implementation, such as multiple modules can be combined or integrated into another system, 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 an indirect coupling or communication connection through some interfaces, devices or modules, which can be 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 distributed on multiple network units. Some or all of the modules may be selected according to actual needs to implement the solution of this embodiment.

[0184] In addition, each functional module in each embodiment of the present application can be integrated into one processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit. The above-mentioned module-composed unit can be implemented in the form of hardware or in the form of hardware plus software functional units.

[0185] The above-mentioned integrated module implemented in the form of a software function module can be stored in a computer-readable storage medium. The above-mentioned software function module is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to perform some steps of the methods of various embodiments of the present application.

[0186] It should be understood that the above processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the invention can be directly embodied as being executed by a hardware processor, or can be executed by a combination of hardware and software modules in the processor.

[0187] The memory may include a high-speed RAM memory, and may also include a 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 disk, etc.

[0188] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or 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 ease of representation, the bus in the drawings of this application is not limited to only one bus or one type of bus.

[0189] The above 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 disk or optical disk. The storage medium can be any available medium that can be accessed by a general or special purpose computer.

[0190] An exemplary storage medium is coupled to a processor so that the processor can 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 main control device.

Claims

1. A frequency response measurement system, characterized in that: Used to measure an electro-optical modulator to be tested; the system comprises: A light source device, the light source device is used to provide a continuous light signal to the electro-optic modulator to be tested; A signal source device, the signal source device is used to provide a pulse signal to the electro-optical modulator to be tested, wherein adjacent pulses in the pulse signal have a fixed phase relationship; A measuring device, wherein the measuring device is used to collect a modulated optical signal output by the electro-optical modulator to be tested according to the optical signal and the pulse signal, and convert the modulated optical signal into an electrical signal, wherein the electrical signal is used to calculate a frequency response of the electro-optical modulator to be tested, wherein the frequency response at least includes a phase-frequency response.

2. The system according to claim 1, characterized in that The pulse signal is a high-frequency electric comb signal; The signal source device includes an optical frequency comb generator and a first photoelectric converter; The optical frequency comb generator is used to generate an optical frequency comb signal; The first photoelectric converter is used to convert the optical frequency comb signal into a high-frequency electric comb signal, and output the high-frequency electric comb signal to the electro-optical modulator to be tested.

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

4. The system according to claim 2, characterized in that The system also 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 measuring device respectively.

5. The system according to any one of claims 2 to 4, characterized in that: The first photoelectric converter is also used to output the high-frequency electric comb signal to the measuring device; The measuring device is specifically used for: Calculating a first frequency response of the first photoelectric converter according to the high-frequency electric comb signal; Calculating a second frequency response according to the electrical signal; The frequency response of the electro-optic modulator to be tested is calculated according to the second frequency response and the first frequency response.

6. The system according to claim 5, characterized in that The measuring device comprises a second photoelectric converter, a collection module and a processing module; The second photoelectric converter is used to convert the modulated optical signal into an electrical signal; 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 tested according to the collected electrical signal; the frequency response includes an amplitude-frequency response and a phase-frequency response.

7. The system according to claim 6, characterized in that The measuring device is an oscilloscope, and the bandwidth of the oscilloscope matches the bandwidth of the electro-optic modulator to be measured.

8. The system according to any one of claims 2 to 4, characterized in that: The system further comprises a processing device, and the measuring device comprises a third photoelectric converter and a collection module; The third photoelectric 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 tested according to the collected electrical signal, and the frequency response includes an amplitude-frequency response and a phase-frequency response.

9. The system according to claim 8, characterized in that The first photoelectric converter is also used to output the high-frequency electric comb signal to the processing device; The processing device is also used for: Calculating a first frequency response of the first photoelectric converter according to the high-frequency electric comb signal; Calculating a second frequency response according to the electrical signal; The frequency response of the electro-optic modulator to be tested is calculated according to the second frequency response and the first frequency response.

10. A frequency response measurement method, characterized in that: Applied in the frequency response measurement system according to any one of claims 1 to 6, the method comprises: The measuring device collects a modulated optical signal output by the electro-optical 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; The measuring device converts the modulated optical signal into an electrical signal; The measuring device calculates the frequency response of the electro-optic modulator to be measured according to the electrical signal, and the frequency response at least includes a phase-frequency response.

11. The method according to claim 10, characterized in that The method further comprises: The measuring device receives the high-frequency electric comb signal sent by the first photoelectric converter in the signal source device; The measuring device calculates a first phase-frequency response of the first photoelectric converter according to the high-frequency electric comb signal; The measuring device calculates a second phase-frequency response based on the electrical signal; 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.

12. A frequency response measurement method, characterized in that: Applied in the frequency response measurement system of claim 8 or 9, the method comprises: The processing device receives the electrical signal; The processing device calculates the frequency response of the electro-optic modulator to be tested according to the electrical signal, and the frequency response at least includes a phase-frequency response.

13. The method according to claim 12, characterized in that The method further comprises: The processing device receives the high-frequency electric comb signal sent by the first photoelectric converter in the signal source device; The processing device calculates a first frequency response of the first photoelectric converter according to the high-frequency electric comb signal; The processing device calculates a second frequency response based on the electrical signal; The processing device calculates the frequency response of the electro-optic modulator to be tested according to the second frequency response and the first frequency response.

14. A measuring device, characterized in that The invention comprises a processor, a memory and a computer program stored in the memory and executable on the processor, wherein when the program is executed by the processor, the method according to claim 10 or 11, or the method according to claim 12 or 13 is implemented.

15. The device according to claim 14, characterized in that The processor is further configured to: Receiving a high-frequency electric comb signal sent by a first photoelectric converter in a signal source device; Calculating a first phase-frequency response of the first photoelectric converter according to the high-frequency electric comb signal; Calculate a second phase-frequency response according to the electrical signal; The phase-frequency response of the electro-optic modulator to be tested is calculated according to the second phase-frequency response and the first phase-frequency response.

16. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method of claim 10 or 11, or the method of claim 12 or 13 is implemented.

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