Frequency stabilization control method, device and system for dfb laser

Abstract

The application provides a DFB laser frequency stabilization control method, device and system, and relates to the technical field of laser devices. The method comprises the following steps: continuously changing the temperature of a target DFB laser so that the output frequency of the target DFB laser approaches a fixed value of the output frequency of a reference DFB laser; collecting the beat frequency between the reference DFB laser and the target DFB laser after each change of the temperature of the target DFB laser; and monitoring in real time whether the frequency difference between the beat frequencies collected continuously for two times satisfies a preset temperature-frequency characteristic. If the frequency difference between the beat frequencies collected continuously for two times satisfies the characteristic, the temperature of the target DFB laser is adjusted according to a feedback control algorithm so that the frequency offset of the target DFB laser satisfies a preset frequency stabilization condition. The application can ensure the precision and reliability of laser frequency stabilization control on the basis of reducing the cost and complexity of laser frequency stabilization control, thereby effectively suppressing frequency offset.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser devices, and particularly to a DFB laser frequency stabilization control method, device and system. BACKGROUND

[0002] In the field of optical communication, due to the very high frequency of light waves, a slight frequency offset also affects the transmission performance and reliability of the communication system. Frequency stability is an important guarantee for reliable and accurate data transmission. There are many methods to realize laser frequency stabilization, one of which is to realize frequency locking through optical and electrical feedback mechanisms. By locking the laser frequency with a reference signal (such as atomic transition frequency, cavity mode frequency, etc.), high stability and high precision control of the laser frequency can be achieved. Frequency-locked lasers are widely used in precision measurement, spectroscopy, optical communication and other fields. At present, there are many laser frequency stabilization schemes. In order to improve the frequency stabilization accuracy, the existing frequency stabilization system usually uses high-precision ECL lasers (i.e. external cavity lasers) and other high-cost narrow linewidth lasers to achieve high-precision frequency stabilization.

[0003] However, in the existing laser frequency stabilization method, the application cost of the ECL laser is high and the frequency stabilization control system is complex, thereby increasing the cost and complexity of the laser frequency stabilization control. If the ECL laser is directly replaced by a lower-cost laser, the accuracy and reliability of the laser frequency stabilization control cannot be guaranteed.

[0004] Therefore, there is an urgent need to design a laser frequency stabilization control method that can reduce the cost of laser frequency stabilization control while ensuring the accuracy and reliability of laser frequency stabilization control. SUMMARY

[0005] In view of this, the embodiments of the present application provide a DFB laser frequency stabilization control method, device and system to eliminate or improve one or more defects in the prior art.

[0006] One aspect of the present application provides a DFB laser frequency stabilization control method, comprising:

[0007] continuously changing the temperature of a target DFB laser so that the output frequency of the target DFB laser approaches a fixed value of the output frequency of a reference DFB laser, wherein the target DFB laser and the reference DFB laser both meet their respective preset frequency range requirements;

[0008] after each change in the temperature of the target DFB laser, the beat frequency between the reference DFB laser and the target DFB laser is collected, and it is monitored in real time whether the frequency difference between the beat frequencies collected continuously for two times meets a preset temperature-frequency characteristic;

[0009] If the frequency difference between the beat frequency of the two consecutive acquisitions meets the temperature frequency characteristic, the temperature of the target DFB laser is regulated according to a feedback control algorithm to make the frequency offset of the target DFB laser meet a preset frequency stability condition.

[0010] In some embodiments of the present application, the frequency range requirement corresponding to the reference DFB laser includes that the output frequency of the reference DFB laser is in an intermediate value range in a temperature frequency overlap range; wherein the temperature frequency overlap range is a frequency value overlap range between the output frequencies of the reference DFB laser and the target DFB laser respectively in a TEC operating temperature range; and the intermediate value range refers to a numerical range in which the difference between each value and the intermediate value of the temperature frequency overlap range is less than a first threshold value.

[0011] The frequency range requirement corresponding to the target DFB laser includes that the output frequency of the target DFB laser is in a high frequency range in the temperature frequency overlap range, wherein the high frequency range is a numerical range in which each value of the frequency in the temperature frequency overlap range is higher than each value in the intermediate value range.

[0012] Correspondingly, before the temperature of the target DFB laser is continuously changed to make the output frequency of the target DFB laser close to the output frequency fixed value of the reference DFB laser, the method further includes:

[0013] Based on the micro control unit corresponding to the reference DFB laser, the temperature and the applied current of the reference DFB laser are regulated to the initial temperature and the initial current corresponding to the reference DFB laser respectively, so that the output frequency of the reference DFB laser is in the intermediate value range in the temperature frequency overlap range, and the temperature and the applied current of the reference DFB laser are fixed, so that the current output frequency of the reference DFB laser is taken as the output frequency fixed value.

[0014] And, based on the micro control unit corresponding to the target DFB laser, the temperature and the applied current of the target DFB laser are regulated to the initial temperature and the initial current corresponding to the target DFB laser respectively, so that the current output frequency of the target DFB laser is in the high frequency range in the temperature frequency overlap range.

[0015] In some embodiments of the present application, the continuous change of the temperature of the target DFB laser to make the output frequency of the target DFB laser close to the output frequency fixed value of the reference DFB laser includes:

[0016] The output frequency fixed value of the reference DFB laser is taken as an output frequency target of the target DFB laser, and the temperature of the target DFB laser is continuously changed by a preset first temperature step based on a micro control unit corresponding to the target DFB laser, so that the output frequency of the target DFB laser approaches the output frequency fixed value of the reference DFB laser.

[0017] In some embodiments of the present application, the collecting the beat frequency between the reference DFB laser and the target DFB laser after each change of the temperature of the target DFB laser respectively includes:

[0018] After each change of the temperature of the target DFB laser, the beat signal of the reference DFB laser and the target DFB laser collected by an integrated coherent receiver respectively connected to the reference DFB laser and the target DFB laser is controlled, wherein the integrated coherent receiver is used to collect the laser signal of the reference DFB laser and the target DFB laser respectively and convert the laser signal into an electrical signal to generate a corresponding beat signal after each change of the temperature of the target DFB laser, and the beat signal is transmitted to a frequency collecting module;

[0019] The beat frequency corresponding to the beat signal collected by the frequency collecting module after each reception of the beat signal is received, wherein the beat frequency between the reference DFB laser and the target DFB laser is the frequency difference between the current output frequency of the reference DFB laser and the output frequency fixed value.

[0020] In some embodiments of the present application, the real-time monitoring whether the frequency difference between the beat frequencies collected continuously twice satisfies a preset temperature frequency characteristic includes:

[0021] The real-time monitoring whether the frequency difference between the two beat frequencies collected continuously twice and the temperature difference between the temperatures applied to the target DFB laser when the two beat frequencies are collected respectively meet a preset temperature frequency characteristic, wherein the temperature frequency characteristic includes a preset curve representing the corresponding relationship between the frequency difference and the temperature difference corresponding to the target DFB laser.

[0022] In some embodiments of the present application, if the frequency difference between the beat frequencies collected continuously twice satisfies the temperature frequency characteristic, the temperature of the target DFB laser is adjusted according to a feedback control algorithm, so that the frequency offset of the target DFB laser satisfies a preset frequency stability condition, which includes:

[0023] If the frequency difference between the beat frequency collected twice in succession meets the temperature frequency characteristic, the temperature currently applied to the target DFB laser is set as a target temperature;

[0024] A second temperature step is set according to the beat frequency currently corresponding to the target DFB laser, and a temperature value after the target temperature is decreased by the second temperature step is set as a first temperature, and a temperature value after the target temperature is increased by the second temperature step is set as a second temperature;

[0025] A down-regulation step: regulating the current temperature of the target DFB laser to the first temperature, and continuously collecting and adding the beat frequency between the reference DFB laser and the target DFB laser to obtain a corresponding down-regulation frequency sum; an up-regulation step: regulating the current temperature of the target DFB laser to the second temperature, and continuously collecting and adding the beat frequency between the reference DFB laser and the target DFB laser to obtain a corresponding up-regulation frequency sum; comparing the sizes of the down-regulation frequency sum and the up-regulation frequency sum; if the current down-regulation frequency sum is less than the up-regulation frequency sum, the second temperature step is re-set according to the beat frequency currently corresponding to the target DFB laser, and the down-regulation step is executed; if the current down-regulation frequency sum is greater than the up-regulation frequency sum, the second temperature step is re-set according to the beat frequency currently corresponding to the target DFB laser, and the up-regulation step is executed, so that the frequency offset of the target DFB laser meets a preset frequency stabilization condition, wherein the frequency stabilization condition includes that when the ambient temperature of the target DFB laser changes in a preset temperature range, the frequency offset of the target DFB laser is also in a preset frequency range.

[0026] Another aspect of the present application provides a DFB laser frequency stabilization control device, comprising:

[0027] A temperature regulation module is configured to continuously change the temperature of a target DFB laser so that the output frequency of the target DFB laser approaches a fixed value of the output frequency of a reference DFB laser, wherein the target DFB laser and the reference DFB laser both meet a respective preset frequency range requirement;

[0028] An acquisition and monitoring module is configured to collect the beat frequency between the reference DFB laser and the target DFB laser after each change of the temperature of the target DFB laser, and to monitor in real time whether the frequency difference between the beat frequency collected twice in succession meets a preset temperature frequency characteristic;

[0029] a feedback control module, configured to, if a frequency difference between the beat frequency collected twice in succession meets the temperature frequency characteristic, regulate a temperature of the target DFB laser according to a feedback control algorithm, so that the frequency offset of the target DFB laser meets a preset frequency stability condition.

[0030] A third aspect of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the DFB laser frequency stabilization control method when executing the computer program.

[0031] A fourth aspect of the present application provides a computer readable storage medium, having a computer program stored thereon, wherein the computer program is executed by a processor to implement the DFB laser frequency stabilization control method.

[0032] A fifth aspect of the present application provides a computer program product, comprising a computer program, wherein the computer program is executed by a processor to implement the DFB laser frequency stabilization control method.

[0033] A sixth aspect of the present application provides a DFB laser frequency stabilization control system, comprising: a main controller, an integrated coherent receiver, a first laser device, a second laser device, and a frequency collection module connected to the main controller respectively; the integrated coherent receiver is connected to the frequency collection module, the first laser device, and the second laser device respectively;

[0034] The main controller is configured to execute the DFB laser frequency stabilization control method provided in the first aspect;

[0035] The first laser device is provided with a first micro control unit, a first digital-to-analog converter, a first temperature control unit, a first constant current source, and the reference DFB laser, the first micro control unit is connected to the main controller and the first digital-to-analog converter respectively, the first digital-to-analog converter is connected to the first temperature control unit and the first constant current source respectively, the first temperature control unit and the first constant current source are connected to the reference DFB laser respectively, and the reference DFB laser is connected to the integrated coherent receiver;

[0036] The second laser device is provided with a second micro control unit, a second digital-to-analog converter, a second temperature control unit, a second constant current source, and the target DFB laser, the second micro control unit is connected to the main controller and the second digital-to-analog converter respectively, the second digital-to-analog converter is connected to the second temperature control unit and the second constant current source respectively, the second temperature control unit and the second constant current source are connected to the target DFB laser respectively, and the target DFB laser is connected to the integrated coherent receiver.

[0037] The first micro-control unit is configured to regulate the first temperature control unit to change the temperature of the reference DFB laser and / or regulate the first constant current source to apply current to the reference DFB laser according to the control signal of the main controller; and the second micro-control unit is configured to regulate the second temperature control unit to change the temperature of the target DFB laser and / or regulate the second constant current source to apply current to the target DFB laser according to the control signal of the main controller.

[0038] The integrated coherent receiver is configured to, after each time the temperature of the target DFB laser is changed, collect the laser signals of the reference DFB laser and the target DFB laser respectively, and convert the laser signals into corresponding beat signals, and transmit the beat signals to the frequency collection module.

[0039] The frequency collection module is configured to, after each time the beat signal is received, collect the beat frequency corresponding to the beat signal, and transmit the beat frequency to the main controller.

[0040] In some embodiments of the present application, the integrated coherent receiver is provided with a local oscillator light port and an optical carrier port, so that the integrated coherent receiver receives the laser signal emitted by the target DFB laser from the local oscillator light port, and receives the laser signal emitted by the reference DFB laser from the optical carrier port.

[0041] In some embodiments of the present application, the frequency collection module comprises an SMA connector, a frequency divider, a comparator and a counter connected in sequence.

[0042] The SMA connector is configured to receive the beat signal transmitted by the integrated coherent receiver, and transmit the beat signal to the frequency divider.

[0043] The frequency divider is configured to perform frequency division processing on the beat signal, and transmit the beat signal after frequency division processing to the comparator.

[0044] The comparator is configured to convert the beat signal after frequency division processing into a binary signal, and transmit the binary signal to the counter.

[0045] The counter is configured to perform level counting on the binary signal to obtain the corresponding beat frequency.

[0046] The DFB laser frequency stabilization control method provided in the application can realize low-cost frequency offset measurement by using a low-cost target DFB laser and by adding a reference DFB laser as a reference laser, so as to perform frequency stabilization control, thereby reducing system complexity and cost. Meanwhile, by monitoring the beat frequency of the laser in real time and by using a feedback control mechanism to realize high-precision stabilization of the frequency through accurate adjustment, the frequency offset can be effectively inhibited. The system design of the DFB laser frequency stabilization control is compact, easy to integrate with existing coherent optical communication equipment, and does not need to make large-scale modification to the existing system. The system can maintain stable frequency output under different working conditions, adapt to complex environmental factors such as temperature change and vibration, and ensure the reliability of the communication system. That is, the DFB laser frequency stabilization control method provided in the application can ensure the precision and reliability of the laser frequency stabilization control on the basis of reducing the cost and complexity of the laser frequency stabilization control, thereby effectively inhibiting the frequency offset and solving the problem of insufficient laser frequency stability in coherent optical communication, providing technical support for realizing an optical communication system with high performance and high reliability, and promoting the further development and application of coherent optical communication technology.

[0047] Additional advantages, objects, and features of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the application. The objects and other advantages of the application can be realized and attained by the structure particularly pointed out in the description and claims hereof as well as the appended drawings.

[0048] It will be understood by those skilled in the art that the objects and advantages of the present application can not be limited to the above specifically described, and the above and other objects that can be achieved by the present application will be more clearly understood according to the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0049] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. The components in the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the application. For purposes of clarity and understanding, some portions of the drawings can be exaggerated, such as relative to size, to illustrate some aspects of the application. In the drawings:

[0050] Figure 1 The first flowchart of the DFB laser frequency stabilization method in an embodiment of the application.

[0051] Figure 2 The second flowchart of the DFB laser frequency stabilization method in an embodiment of the application.

[0052] Figure 3 The structure diagram of the DFB laser frequency stabilization device in an embodiment of the application.

[0053] Figure 4 The structure diagram of the DFB laser frequency stabilization system in an embodiment of the application.

[0054] Figure 5 The overall architecture structure diagram of the DFB laser frequency stabilization system in an application example of the application.

[0055] Figure 6 The specific structure diagram of the DFB laser frequency stabilization system in an application example of the application.

[0056] Figure 7 The flowchart of the DFB laser frequency stabilization method in an application example of the application.

[0057] Reference signs:

[0058] 1, main controller;

[0059] 11, indicator light;

[0060] 12, USB interface;

[0061] 13, third micro control unit;

[0062] 2, integrated coherent receiver;

[0063] 21, local oscillator optical port;

[0064] 22, optical carrier port;

[0065] 3, first laser device;

[0066] 31, first micro control unit;

[0067] 32. a first digital-to-analog converter;

[0068] 33. a first temperature control unit;

[0069] 34. a first constant current source;

[0070] 35. a reference DFB laser;

[0071] 4. a second laser device;

[0072] 41. a second micro control unit;

[0073] 42. a second digital-to-analog converter;

[0074] 43. a second temperature control unit;

[0075] 44. a second constant current source;

[0076] 45. a target DFB laser;

[0077] 5. a frequency acquisition module;

[0078] 51. an SMA connector;

[0079] 52. a frequency divider;

[0080] 53. a comparator;

[0081] 54. a counter;

[0082] 55. a display;

[0083] 6. an oscilloscope;

[0084] 7. a control terminal;

[0085] 71. a host computer. DETAILED DESCRIPTION

[0086] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the embodiments and drawings. Herein, the illustrative embodiments of the present application and their descriptions are used to explain the present application, but are not used to limit the present application.

[0087] It should also be noted that, in order to avoid the present application being obscured by unnecessary details, only the structures and / or processing steps closely related to the solutions according to the present application are shown in the drawings, and other details not closely related to the present application are omitted.

[0088] It should be emphasized that the term "comprises / comprising" when used in this specification is taken to specify the presence of stated features, elements, steps or components, but does not preclude the presence or addition of one or more other features, elements, steps, components, or groups thereof.

[0089] It should also be noted that the term "connection" can refer not only to a direct connection, but also to an indirect connection with an intermediate object, unless otherwise specified.

[0090] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0091] In a coherent optical communication system, the output frequency stability of the laser is a key technical bottleneck. In particular, for low-cost lasers, the output frequency is easily affected by environmental factors such as temperature changes, resulting in drift, which in turn affects the transmission performance and stability of the system. Existing systems have demands in multiple dimensions such as complexity, capacity and sensitivity, and future optical access networks need to meet the requirements of high performance and low cost to break through the performance limit of the whole network of coherent optical access.

[0092] It should be noted that the ECL laser is a kind of ultra-narrow linewidth laser, whose spectral linewidth is very narrow, and the width of its laser spectrum is usually less than 1MHz, and even can reach several Hz level. Compared with traditional lasers, ultra-narrow linewidth lasers have extremely high frequency stability and coherence, and can provide very precise and stable laser frequency. Due to its excellent frequency control characteristics, ultra-narrow linewidth lasers play a crucial role in many high-precision measurement and application fields. With the continuous development of optical frequency standards, the technology and application of ultra-narrow linewidth lasers will be further expanded and deepened in the future. In order to adapt to the huge bandwidth demand, the ITU-T standardization department has made great progress in defining high-speed passive optical network (PON) with 50Gb / s line rate, and has gradually matured in technology, and can start to explore super 50gPON. Higher line rate has higher requirements for frequency stability.

[0093] In the field of laser technology, frequency stability is one of the key indicators to measure the performance of a laser. The output frequency of a laser is influenced by various factors, among which temperature variation is one of the main causes of frequency shift. In order to achieve high-precision frequency stability, the operating temperature of the laser must be precisely controlled. TEC (Thermoelectric Cooler) modules play a crucial role in this process. Based on the Peltier effect, TEC modules transfer heat by applying a direct current between two semiconductor materials (P-type and N-type). When current passes through the TEC module, one end absorbs heat (cold end), and the other end releases heat (hot end). By changing the direction of the current, the cold and hot ends can be switched, thus achieving cooling or heating functions. This feature enables TEC modules to precisely control the temperature of a laser, ensuring its stable operation at a constant temperature. Advanced PID control algorithms are employed, combined with high-precision temperature sensors, to achieve precise control of the laser temperature, with a control accuracy of 0.01℃ or even higher.

[0094] In view of the problems of insufficient laser frequency stability, complex system, high cost, difficulty in popularization in practical application, and difficulty in balancing frequency stabilization precision and response speed in the existing laser frequency stabilization (i.e., frequency stabilization) mode, firstly, a DFB laser (Distributed Feedback Laser) which also belongs to a narrow linewidth laser is considered to replace an ECL laser. However, although the DFB laser has a lower cost, its frequency stabilization precision is not as good as that of the ECL laser. If a DFB laser with a lower cost is used, the frequency stabilization precision needs to be sacrificed. That is, if only the hardware is replaced, although the cost can be effectively reduced, for the actual needs in the field, the frequency stabilization precision needs to be as high as possible, and the precision of the DFB laser may not meet the requirements. Therefore, in order to provide a frequency-locked laser with higher stability, higher precision and lower cost, the designers of the present application also improve and optimize the control algorithm, cleverly realize the measurement of frequency shift by adding a laser as a reference laser, and thus perform frequency stabilization control, so as to realize a low-cost solution for laser frequency stabilization, and reduce the system complexity and cost. By using an automatic feedback control mechanism, the output frequency of the laser is monitored in real time, and high-precision stabilization of the frequency is realized by precise adjustment, so as to effectively suppress the frequency shift. The frequency stabilization system is compact in design and easy to integrate with existing coherent optical communication equipment, without the need for large-scale modification of the existing system. The system can maintain stable frequency output under different working conditions, adapt to complex environmental factors such as temperature change and vibration, and ensure the reliability of the communication system.

[0095] Therefore, in order to solve the problems that the application cost of the ECL laser is high and the frequency stabilization control system is complex in the existing laser frequency stabilization method, and if the ECL laser is directly replaced by a lower-cost laser, the precision and reliability of the laser frequency stabilization control cannot be guaranteed, the embodiments of the present application provide a DFB laser frequency stabilization control method, a DFB laser frequency stabilization control device for executing the DFB laser frequency stabilization control method, an electronic device, a computer readable storage medium, a computer program product and a DFB laser frequency stabilization control system, which can guarantee the precision and reliability of the laser frequency stabilization control on the basis of reducing the cost and complexity of the laser frequency stabilization control, and thus effectively suppress the frequency offset.

[0096] The embodiments are specifically described as follows.

[0097] Based on this, the embodiments of the present application provide a DFB laser frequency stabilization control method which can be implemented by a DFB laser frequency stabilization control device, as shown in Figure 1 The DFB laser frequency stabilization control method specifically includes the following contents.

[0098] Step 100: continuously changing the temperature of a target DFB laser so that the output frequency of the target DFB laser approaches a fixed value of the output frequency of a reference DFB laser, wherein the target DFB laser and the reference DFB laser both meet the respective preset frequency range requirements.

[0099] In one or more embodiments of the present application, the target DFB laser and the reference DFB laser are both DFB lasers. A DFB laser is a special semiconductor laser diode that can emit light of a single frequency, has high stability and precise wavelength control. The core is to introduce a Bragg grating in the active gain region of the laser, and the periodic refractive index change of the grating realizes feedback and wavelength selection of light, so as to realize single-mode operation at a specific wavelength. The DFB laser realizes distributed feedback of light through the periodic structure of the Bragg grating. This feedback mechanism enables the laser to operate in a single mode at a specific wavelength, and has excellent monochromaticity, narrow linewidth and high stability. The linewidth of the DFB laser can generally be within 1 MHz, with extremely high spectral purity. The linewidth of the DFB laser is relatively narrow, which makes the output light have good coherence characteristics. The wavelength stability of the DFB laser is better than that of the traditional laser, the temperature offset is small, and it is suitable for high-precision applications.

[0100] It can be understood that the DFB laser frequency stabilization control device can be a functional module arranged in a main controller (also referred to as a master or master module), and the DFB laser frequency stabilization control device can continuously change the temperature of the target DFB laser through a temperature control unit to make the output frequency of the target DFB laser close to a fixed value of the output frequency of the reference DFB laser, wherein the temperature control unit can include a micro processing unit MCU and a temperature control unit (which can be referred to as a temperature control unit for short) connected to each other, and the micro processing unit MCU controls the temperature control unit connected to the target DFB laser to change the temperature of the target DFB laser according to the signal sent by the DFB laser frequency stabilization control device.

[0101] In step 100, the specific way of making the output frequency of the target DFB laser close to the fixed value of the output frequency of the reference DFB laser can be realized according to a pre-set first temperature step, which will be described in detail in the subsequent embodiments.

[0102] It should be noted that the fixed value of the output frequency of the reference DFB laser refers to the output frequency of the reference DFB laser when the temperature and the applied current are constant. The reference DFB laser serves as a reference device for the target DFB laser to assist the target DFB laser in high-precision frequency stabilization control.

[0103] In one or more embodiments of the present application, the frequency range requirement refers to requirement data for indicating a frequency value range, which can be set by human beings in advance and can be set according to actual application requirements, which will be described in detail in the following embodiments.

[0104] Step 200: After changing the temperature of the target DFB laser each time, the beat frequency between the reference DFB laser and the target DFB laser is collected respectively, and whether the frequency difference between the beat frequencies collected continuously twice satisfies a pre-set temperature frequency characteristic is monitored in real time.

[0105] In step 200, the DFB laser frequency stabilization control device can control the integrated coherent receiver ICR and the frequency collection module respectively connected to the target DFB laser to collect the beat frequency between the reference DFB laser and the target DFB laser after changing the temperature of the target DFB laser each time, wherein the integrated coherent receiver collects the laser signals of the reference DFB laser and the target DFB laser respectively and converts the electrical signals to generate corresponding beat signals, and transmits the beat signals to the frequency collection module; the frequency collection module can collect the beat frequency corresponding to the beat signal each time the beat signal is received.

[0106] It can be understood that the beat signal refers to a periodic amplitude change signal generated by interference when two frequency close waves (such as light waves) are superimposed, and the beat signal is the difference frequency envelope signal of the two frequency close waves. The frequency of the beat signal is the beat frequency. The beat frequency is equal to the frequency difference of the two original waves, that is, the frequency difference between the fixed value of the output frequency of the reference DFB laser and the output frequency of the target DFB laser.

[0107] The temperature frequency characteristic is data used to represent the correlation between the temperature difference and the frequency difference, the temperature difference is the temperature difference between the temperatures applied to the target DFB laser when the two beat frequencies are continuously collected, and the frequency difference is the frequency difference between the two beat frequencies collected continuously twice. In an example, the temperature frequency characteristic can include a preset curve used to represent the corresponding relationship between the frequency difference and the temperature difference corresponding to the target DFB laser. The slope of the curve can be the temperature wavelength variation coefficient of the target DFB laser obtained by pre-test.

[0108] Step 300: If the frequency difference between the two beat frequencies collected continuously twice satisfies the temperature frequency characteristic, the temperature of the target DFB laser is adjusted according to the feedback control algorithm, so that the frequency offset of the target DFB laser satisfies the preset frequency stability condition.

[0109] It should be noted that when the environment temperature of the environment where the target DFB laser is located changes, in order to control the frequency offset, it is necessary to maintain the frequency stability of the target DFB laser, so it is necessary to observe the frequency offset of the target DFB laser, and the frequency offset is also referred to as frequency offset.

[0110] The environment temperature is not the same as the temperature mentioned in the present application. The temperature mentioned in the present application refers to the temperature controlled by the internal temperature control of the target DFB laser or the reference DFB laser. The environment temperature refers to the environment temperature outside the device shell of the target DFB laser or the reference DFB laser. The device shell has a certain heat preservation effect, but the target DFB laser will still be affected by the environment temperature to produce frequency offset, so it is necessary to perform the DFB laser frequency stabilization control method provided in the present application to control the temperature of the target DFB laser, and then realize the frequency stabilization control of the target DFB laser.

[0111] That is to say, the output frequency of the laser is usually affected by environmental factors such as temperature and mechanical vibration. When the ambient temperature changes, the temperature inside the laser will change if there is no additional control, and the optical elements of the laser will expand or contract due to heat, causing the optical path length to change, thereby causing the output frequency of the laser to change, which is called frequency offset. The amount of change in the output frequency is the amount of frequency offset. The frequency offset described in the embodiments of the present application refers only to the frequency offset under the influence of temperature. However, due to the high laser frequency, existing observation of laser frequency and offset requires very high-cost instruments such as spectrometers. The present application designs a lower-cost solution: by adding a reference DFB laser with a constant output frequency, the output frequencies of the reference DFB laser and the target DFB laser to be observed are input into the ICR, so that the ICR outputs a beat frequency signal. The frequency of the beat frequency signal is low and easy to measure and collect, so the embodiments of the present application can use frequency collection modules with simple architecture such as frequency dividers and comparators. Since the output frequency of the reference DFB laser is constant, the frequency offset of the target DFB laser is equal to the change in the beat frequency of the target DFB laser, which is the beat frequency between the reference DFB laser and the target DFB laser. By collecting the beat frequency and obtaining its change, the frequency offset of the target DFB laser can be obtained, and feedback control can be performed.

[0112] In one or more embodiments of the present application, the frequency stabilization condition can be set as: when the ambient temperature of the target DFB laser changes within a preset temperature range, the frequency offset of the target DFB laser is also within a preset frequency range, and then it can be determined that the current frequency offset of the target DFB laser is in a frequency stable state. The preset temperature range and the frequency range can be obtained after artificial measurement. In one example, the preset temperature range can be set to 10-60°C; the frequency range can be set to [-100MHz, +100MHz]. That is, through the feedback control algorithm of step 300, the frequency stabilization accuracy and reliability can be effectively improved, and the frequency offset of the target DFB laser within the temperature change of 10-60°C does not exceed ±100MHz.

[0113] From the above description, the DFB laser frequency stabilization control method provided by the embodiment of the application stabilizes the frequency of the DFB laser, and adds a laser with an unchanged output frequency as a reference to measure the frequency offset, thereby performing feedback control. Through the feedback control algorithm, the output frequency of the target DFB laser is close to the reference DFB laser, and the beat frequency is stabilized within ±100 MHz. When the ambient temperature changes between 10-60℃, the system can achieve frequency stabilization. This also achieves that the frequency offset of the target DFB laser does not exceed ±100 MHz within the temperature change of 10-60℃.

[0114] In order to further improve the reliability and effectiveness of the DFB laser frequency stabilization control, in the DFB laser frequency stabilization control method provided by the embodiment of the application, the frequency range requirement corresponding to the reference DFB laser includes that the output frequency of the reference DFB laser is in the middle value range in the temperature frequency overlap range; wherein the temperature frequency overlap range is the frequency value overlap range between the output frequencies of the reference DFB laser and the target DFB laser respectively in the TEC working temperature range; and the middle value range refers to a numerical range formed by each numerical value whose difference with the middle value of the temperature frequency overlap range is less than a first threshold value.

[0115] The frequency range requirement corresponding to the target DFB laser includes that the output frequency of the target DFB laser is in the high frequency range in the temperature frequency overlap range, wherein the high frequency range is a numerical range formed by each numerical value whose frequency in the temperature frequency overlap range is higher than each numerical value in the middle value range.

[0116] The TEC working temperature range is usually between -55℃ and 125℃. The first threshold value can be set to any value greater than 0 according to actual application needs.

[0117] That is to say, the temperature frequencies of the two DFB lasers can be calibrated first to ensure that there is an overlapping part of the temperature frequencies of the reference DFB laser and the target DFB laser in the TEC working temperature range, and the temperature frequency characteristics of the overlapping part are calculated.

[0118] Correspondingly, referring to Figure 2 , the step 100 in the DFB laser frequency stabilization control method further specifically includes the following content before the step 100:

[0119] Step 010: based on the micro control unit corresponding to the reference DFB laser, the temperature and applied current of the reference DFB laser are respectively regulated to the initial temperature and initial current corresponding to the reference DFB laser, so that the output frequency of the reference DFB laser is in the middle value range of the temperature frequency overlap range, and the temperature and applied current of the reference DFB laser are fixed, so that the current output frequency of the reference DFB laser is as the output frequency fixed value.

[0120] And, step 020: based on the micro control unit corresponding to the target DFB laser, the temperature and applied current of the target DFB laser are respectively regulated to the initial temperature and initial current corresponding to the target DFB laser, so that the current output frequency of the target DFB laser is in the high frequency range of the temperature frequency overlap range.

[0121] In an example, the DFB laser frequency stabilization control device transmits signals to the micro control units (MCU) of the reference DFB laser and the target DFB laser through the pre-set internal program, and the MCU transmits signals to the digital-to-analog converter (16-bit DAC), at which time the signals are digital signals. The 16-bit DAC converts the digital signal into an analog signal and transmits it to the temperature control and constant current source, which jointly control the DFB laser connected thereto. The digital signal is a discrete signal, and both time and amplitude are quantized (usually in binary form). Since the DAC used is 16-bit, numbers between 0 and 65535 (decimal value) can be used. The analog signal is continuous in amplitude and time, which can be converted from the digital signal by the DAC for current and temperature adjustment.

[0122] In order to further improve the control accuracy, reliability and effectiveness of the target DFB laser output frequency approaching the output frequency fixed value of the reference DFB laser, in the DFB laser frequency stabilization control method provided in the embodiment of the present application, referring to Figure 2 , the step 100 in the DFB laser frequency stabilization control method specifically includes the following contents:

[0123] Step 110: the output frequency fixed value of the reference DFB laser is taken as the output frequency target of the target DFB laser, and based on the micro control unit corresponding to the target DFB laser, the temperature of the target DFB laser is continuously changed in a pre-set first temperature step, so that the output frequency of the target DFB laser approaches the output frequency fixed value of the reference DFB laser.

[0124] Specifically, the current and temperature of the reference DFB laser are kept unchanged, and the temperature of the target DFB laser is changed. A fixed temperature interval is set, which is named as a first temperature step, and the unit is Celsius. A value of 0.08°C or less can be used as the value of the first temperature step of the target DFB laser, and 0.08°C is preferred.

[0125] In the formula, the first temperature step considers a relatively small value below 1 MHz. It is easy to know that 1550 nm is often used as the light source wavelength in the fiber communication system, and assuming that the light source spectral width is 0.1 nm, the maximum bandwidth is 12.4 GHz. The bandwidth of 1 GHz corresponds to a spectral width of about 8 pm. According to actual tests, the temperature wavelength variation coefficient of the DFB laser is 0.1 nm / °C (±0.02 nm / °C). Therefore, the bandwidth variation of 1 GHz corresponds to a temperature variation of about 0.08°C. For each increase or decrease of 0.08°C, the laser frequency emitted by the laser will decrease or increase by about 1 GHz, that is, 1000 MHz. Therefore, a value of 0.08°C or less can be used as the step of the target temperature change, and 0.08°C is preferred. The lower limit of the value is related to the number of bits of the DAC used. For different fiber communication systems, different laser wavelengths can be used, and the setting of the step value will change.

[0126] In order to further improve the convenience and effectiveness of collecting the beat frequency between the reference DFB laser and the target DFB laser and further reduce the cost and complexity of the DFB laser frequency stabilization control, in the DFB laser frequency stabilization control method provided in the embodiment of the present application, referring to Figure 2 , the step 200 in the DFB laser frequency stabilization control method specifically includes the following contents:

[0127] Step 210: After changing the temperature of the target DFB laser each time, the beat frequency signal between the reference DFB laser and the target DFB laser collected by the integrated coherent receiver connected to the reference DFB laser and the target DFB laser respectively is controlled, wherein the integrated coherent receiver is used to collect the laser signals of the reference DFB laser and the target DFB laser respectively and perform electrical signal conversion to generate corresponding beat frequency signals after changing the temperature of the target DFB laser each time, and the beat frequency signals are transmitted to the frequency collection module.

[0128] Step 220: receiving the beat frequency corresponding to the beat frequency signal collected by the frequency collection module after receiving the beat frequency signal each time, wherein the beat frequency between the reference DFB laser and the target DFB laser is the frequency difference between the current output frequency of the reference DFB laser and the fixed value of the output frequency.

[0129] In an example, in order to further reduce the cost and complexity of frequency acquisition of the DFB laser, the frequency acquisition module comprises: an SMA connector, a frequency divider, a comparator and a counter connected in sequence; the SMA connector is used for receiving the beat frequency signal transmitted by the integrated coherent receiver and transmitting the beat frequency signal to the frequency divider; the frequency divider is used for frequency division processing of the beat frequency signal and transmitting the frequency-division-processed beat frequency signal to the comparator; the comparator is used for converting the frequency-division-processed beat frequency signal into a binary signal and sending the binary signal to the counter; and the counter is used for level counting of the binary signal to obtain the corresponding beat frequency.

[0130] In order to further improve the judgment effectiveness and accuracy of the frequency difference between the two beat frequencies acquired successively satisfying the preset temperature-frequency characteristic, in a DFB laser frequency stabilization control method provided by an embodiment of the present application, referring to Figure 2 , the step 220 in the step 200 in the DFB laser frequency stabilization control method further comprises the following content: a step 230 of monitoring in real time whether the frequency difference between the two beat frequencies acquired successively and the temperature difference between the temperatures applied to the target DFB laser when the two beat frequencies are acquired respectively meet the preset temperature-frequency characteristic, wherein the temperature-frequency characteristic comprises a preset curve for representing the corresponding relationship between the frequency difference and the temperature difference corresponding to the target DFB laser.

[0131] In order to further improve the stability, reliability and control precision of the frequency offset of the target DFB laser satisfying the preset frequency stabilization condition, in a DFB laser frequency stabilization control method provided by an embodiment of the present application, referring to Figure 2 , the step 300 in the DFB laser frequency stabilization control method comprises the following content:

[0132] a step 310 of setting the temperature currently applied to the target DFB laser as a target temperature if the frequency difference between the two beat frequencies acquired successively meets the temperature-frequency characteristic.

[0133] a step 320 of setting a second temperature step according to the beat frequency currently corresponding to the target DFB laser; and setting a temperature value after the target temperature is reduced by one second temperature step as a first temperature and setting a temperature value after the target temperature is increased by one second temperature step as a second temperature.

[0134] Step 330: Down-regulation step: regulating the current temperature of the target DFB laser to the first temperature, and continuously collecting and summing the beat frequencies between the reference DFB laser and the target DFB laser to obtain the corresponding down-regulation frequency sum.

[0135] Step 340: Up-regulation step: regulating the current temperature of the target DFB laser to the second temperature, and continuously collecting and summing the beat frequencies between the reference DFB laser and the target DFB laser to obtain the corresponding up-regulation frequency sum.

[0136] Step 350: Comparing the sizes of the down-regulation frequency sum and the up-regulation frequency sum; if the current down-regulation frequency sum is less than the up-regulation frequency sum, resetting the second temperature step according to the current corresponding beat frequency of the target DFB laser and performing the down-regulation step; if the current down-regulation frequency sum is greater than the up-regulation frequency sum, resetting the second temperature step according to the current corresponding beat frequency of the target DFB laser and performing the up-regulation step, so that the frequency offset of the target DFB laser meets the preset frequency stability condition, wherein the frequency stability condition includes that when the environmental temperature of the target DFB laser changes within a preset temperature range, the frequency offset of the target DFB laser also changes within a preset frequency range.

[0137] It can be understood that the value of the second temperature step is determined according to the current corresponding beat frequency of the target DFB laser, if the current corresponding beat frequency of the target DFB laser is greater than 100Mhz, the value of the second temperature step is set to 0.008℃; if the current corresponding beat frequency of the target DFB laser is less than or equal to 100Mhz, the value of the second temperature step is set to 0.001℃.

[0138] That is, in order to build a new low-cost, wide coverage, high flexibility coherent optical access system, and improve the overall performance of the coherent optical access network, it is necessary to study the simplified coherent transmission architecture of low-cost lasers. Through the laser frequency locking performance control algorithm, the influence of temperature on the performance of ultra-narrow linewidth laser is explored, and the frequency is adjusted through the feedback control algorithm to realize frequency locking. Building a laser frequency stabilization system at low cost is of great significance to the widespread development of coherent optical access systems, and can promote the coverage and high flexibility of the system. In the coherent receiver system, the working principle of the laser is studied in depth to control the frequency offset of the laser, improve the frequency stability of the laser and the stability of the control system. As can be seen, by controlling the frequency stability of the simplified system, the construction cost can be reduced, while the stability and reliability of the laser can be improved, which plays an important role in the research and development of high-rate high-speed passive optical networks (PON). In summary, it is of great significance to realize low-cost laser frequency stabilization in coherent optical communication systems.

[0139] From the software level, the application also provides a DFB laser frequency stabilization control device for executing all or part of the DFB laser frequency stabilization control method, which is described in detail below. Figure 3 The DFB laser frequency stabilization control device specifically includes the following contents:

[0140] A temperature regulation module 10 is configured to continuously change the temperature of a target DFB laser so that the output frequency of the target DFB laser approaches a fixed value of the output frequency of a reference DFB laser, wherein the target DFB laser and the reference DFB laser both meet the respective preset frequency range requirements.

[0141] A collection and monitoring module 20 is configured to collect the beat frequency between the reference DFB laser and the target DFB laser after each change in the temperature of the target DFB laser, and to monitor in real time whether the frequency difference between the beat frequencies collected continuously for two times meets a preset temperature-frequency characteristic.

[0142] A feedback control module 30 is configured to, if the frequency difference between the beat frequencies collected continuously for two times meets the temperature-frequency characteristic, regulate the temperature of the target DFB laser according to a feedback control algorithm, so that the frequency offset of the target DFB laser meets a preset frequency stability condition.

[0143] The embodiments of the DFB laser frequency stabilization control device provided by the application can be specifically used to execute the processing procedures of the embodiments of the DFB laser frequency stabilization control method described above, and the functions thereof will not be described here again. Please refer to the detailed description of the above-mentioned embodiments of the DFB laser frequency stabilization control method.

[0144] The part of the DFB laser frequency stabilization control device that performs DFB laser frequency stabilization control can be completed in a client device such as a main controller. Specifically, it can be selected according to the processing capacity of the client device, and the restrictions of the user's use scenario, etc. The present application does not limit this. If all operations are completed in the client device, the client device can also include a processor for specific processing of DFB laser frequency stabilization control.

[0145] The above-mentioned client device can have a communication module (i.e. a communication unit) that can be communicatively connected with the micro control unit corresponding to the reference DFB laser, the micro control unit corresponding to the target DFB laser, and the frequency acquisition module, etc., to realize data transmission between the micro control unit corresponding to the reference DFB laser, the micro control unit corresponding to the target DFB laser, and the frequency acquisition module. In addition, in order to facilitate monitoring and control, the client device can also be communicatively connected with a remote server, an upper computer, etc. The server can include a server on the task scheduling center side, and in other implementation scenarios, it can also include a server of an intermediate platform, such as a server of a third-party server platform that is communicatively linked with the task scheduling center server. The server can include a single computer device, or a server cluster composed of multiple servers, or a distributed server structure.

[0146] Any suitable network protocol can be used for communication between the above-mentioned server and the client device, including network protocols that have not been developed as of the filing date of the present application. The network protocol can include, for example, TCP / IP protocol, UDP / IP protocol, HTTP protocol, HTTPS protocol, etc. Of course, the network protocol can also include, for example, RPC protocol (Remote Procedure Call Protocol) used on top of the above-mentioned protocols, REST protocol (Representational State Transfer), etc.

[0147] From the above description, the DFB laser frequency stabilization control device provided by the embodiment of the present application can realize low-cost frequency offset measurement by using a low-cost target DFB laser and adding a reference DFB laser as a reference laser, thereby performing frequency stabilization control, and can reduce system complexity and cost. At the same time, by monitoring the beat frequency of the laser in real time and using a feedback control mechanism to realize high-precision stabilization of the frequency through accurate adjustment, the frequency offset can be effectively suppressed. The system design of the DFB laser frequency stabilization control is compact, easy to integrate with existing coherent optical communication equipment, and does not require large-scale modification of the existing system. It can maintain stable frequency output under different working conditions, adapt to complex environmental factors such as temperature changes and vibrations, and ensure the reliability of the communication system. That is, the DFB laser frequency stabilization control method provided by the present application can ensure the precision and reliability of the laser frequency stabilization control on the basis of reducing the cost and complexity of the laser frequency stabilization control, thereby effectively suppressing the frequency offset and solving the problem of insufficient laser frequency stability in coherent optical communication, providing technical support for realizing high-performance and high-reliability optical communication systems, and promoting the further development and application of coherent optical communication technology.

[0148] From the hardware level, the present application further provides an embodiment of a DFB laser frequency stabilization control system, as shown in Figure 4 , the DFB laser frequency stabilization control system specifically includes the following contents:

[0149] The main controller 1, the integrated coherent receiver 2, the first laser device 3, the second laser device 4 and the frequency acquisition module 5 connected to the main controller 1 respectively.

[0150] The integrated coherent receiver 2 is connected to the frequency acquisition module 5, the first laser device 3 and the second laser device 4 respectively.

[0151] The main controller 1 is used to execute the DFB laser frequency stabilization control method provided by the foregoing embodiments.

[0152] The first laser device 3 is provided with a first micro control unit 31, a first digital analog converter 32, a first temperature control unit 33, a first constant current source 34 and the reference DFB laser 35. The first micro control unit 31 is connected to the main controller 1 and the first digital analog converter 32 respectively. The first digital analog converter 32 is connected to the first temperature control unit 33 and the first constant current source 34 respectively. The first temperature control unit 33 and the first constant current source 34 are connected to the reference DFB laser 35 respectively. The reference DFB laser 35 is connected to the integrated coherent receiver 2.

[0153] The second laser device 4 is provided with a second micro control unit 41, a second digital-to-analog converter 42, a second temperature control unit 43, a second constant current source 44 and the target DFB laser 45. The second micro control unit 41 is connected to the main controller 1 and the second digital-to-analog converter 42 respectively. The second digital-to-analog converter 42 is connected to the second temperature control unit 43 and the second constant current source 44 respectively. The second temperature control unit 43 and the second constant current source 44 are connected to the target DFB laser 45 respectively. The target DFB laser 45 is connected to the integrated coherent receiver 2.

[0154] The first micro control unit 31 is configured to control the first temperature control unit 33 to change the temperature of the reference DFB laser 35 and / or control the first constant current source 34 to apply current to the reference DFB laser 35 according to the control signal of the main controller 1. The second micro control unit 41 is configured to control the second temperature control unit 43 to change the temperature of the target DFB laser 45 and / or control the second constant current source 44 to apply current to the target DFB laser 45 according to the control signal of the main controller 1.

[0155] The integrated coherent receiver 2 is configured to collect the laser signals of the reference DFB laser 35 and the target DFB laser 45 respectively and convert the laser signals into electrical signals to generate corresponding beat signals after the temperature of the target DFB laser 45 is changed each time, and transmit the beat signals to the frequency collection module 5.

[0156] The frequency collection module 5 is configured to collect the beat frequency corresponding to the beat signal received each time and transmit the beat frequency to the main controller 1.

[0157] In the embodiment of the DFB laser frequency stabilization control system of the present application, referring to Figure 4 The integrated coherent receiver 2 is provided with a local light port 21 and an optical carrier port 22, so that the integrated coherent receiver 2 receives the laser signal emitted by the target DFB laser 45 from the local light port 21 and receives the laser signal emitted by the reference DFB laser 35 from the optical carrier port 22.

[0158] In the embodiment of the DFB laser frequency stabilization control system of the present application, referring to Figure 4 The frequency collection module 5 comprises an SMA connector 51, a frequency divider 52, a comparator 53 and a counter 54 connected in sequence.

[0159] The SMA connector 51 is configured to receive the beat signal transmitted by the integrated coherent receiver 2 and transmit the beat signal to the frequency divider 52.

[0160] The frequency divider 52 is configured to divide the beat frequency signal and transmit the divided beat frequency signal to the comparator 53.

[0161] The comparator 53 is configured to convert the divided beat frequency signal into a binary signal and transmit the binary signal to the counter 54.

[0162] The counter 54 is configured to count the level of the binary signal to obtain the corresponding beat frequency.

[0163] In order to further illustrate the above-mentioned embodiment, the application further provides a specific application example of a DFB laser frequency stabilization control method implemented by a DFB laser frequency stabilization control system, which is shown in Figure 5 The DFB laser frequency stabilization control system can further include an oscilloscope 6 connected to the integrated coherent receiver and a control terminal 7 connected to the main controller 1, and the control terminal 7 can be implemented by a host computer 71.

[0164] Specifically, as shown in Figure 6 The main controller 1 included in the DFB laser frequency stabilization control system can be connected to the frequency acquisition module 5, the first laser device 3 and the second laser device 4 through three serial ports (i.e. UART1, UART2 and UART3). The main controller 1 can further include an indicator 11 for displaying the working state of the system and a USB interface 12 connected to the host computer 71. The counter 54 can be further connected to a display 55. The main controller 1 is provided with a third micro control unit 13 connected to the serial ports UART1, UART2 and UART3.

[0165] The integrated coherent receiver (which can be abbreviated as ICR) 2 has two input signals, namely the local oscillator light LO and the optical carrier SIG. It outputs eight signals different in carrier component, polarization direction and differential polarity. The expression of the eight signals can be identified in I and Q, in X and Y and in P and N, respectively. I and Q represent two orthogonal carrier components of light, X and Y represent signals of two polarization directions, and P and N represent positive and negative differential signals of the two input signals, respectively. The signal output to the frequency acquisition module is QX, P, which means the positive differential signal of the orthogonal component in the X polarization direction. The signal output to the frequency acquisition module is the beat frequency signal of the two input signals, and the frequency of the beat frequency signal is the difference between the frequencies of the two input signals.

[0166] The first laser device 3 and the second laser device 4 respectively receive and process the signals transmitted by the main controller 1 through the respective corresponding MCUs, and then can be connected to the digital-to-analog converter (which can also be referred to as DAC) through the SPI serial port, and the DAC transmits the signals to the temperature controller and the constant current source respectively, to jointly control the output of the DFB laser.

[0167] The frequency acquisition module 5 receives the ICR output signal, and after the signal passes through the frequency divider and the comparator, the MCU is used for counting, the beat frequency is calculated in real time, the calculation result is displayed on the display screen, and is transmitted to the main control module.

[0168] The photoelectric link of the DFB laser frequency stabilization control system is that the MCU is connected to the two lasers to transmit the setting signals; the laser emitted by the two lasers is connected to the local oscillator light port 21 and the optical carrier port 22 of the coherent receiver ICR, the output of the ICR is connected to the frequency acquisition module 5, and the oscilloscope 6 is used for detection; the frequency acquisition module 5 is connected with the main controller 1 to transmit the setting and feedback signals; the main controller 1 can be connected to the computer as the upper computer 71 through the USB interface 12 to debug the system program and configure the parameters.

[0169] Further, it is referred that the DFB laser and the target DFB laser have the same structure. The laser receives the signal of the main control, receives the digital signal through the internal MCU, and is connected to the DAC. The DAC is used to convert the digital signal transmitted by the MCU into an analog signal, which is input into the temperature controller and the constant current source module respectively, and the two modules jointly control the DFB laser, so that the laser emits a laser of a specific frequency and keeps the temperature stable. The ICR receives two laser signals and converts the optical signal into an electrical signal. The signal output by the ICR is a signal with a lower frequency compared with the input laser signal frequency. This low-frequency signal is the beat frequency signal, which is output to the frequency acquisition module. The frequency acquisition module acquires the frequency of the beat frequency signal and outputs the beat frequency. The frequency acquisition module uses the SMA high-frequency connector for signal input, the frequency divider reduces the frequency of the signal output by the ICR to obtain a low-frequency beat frequency signal. Frequency division refers to reducing the frequency of the input signal by several times. The comparator compares the signal processed by the frequency divider with the preset reference signal, converts the analog signal into a binary signal, so that the counter MCU can count and display the frequency. The counter MCU obtains the binary signal output by the comparator, counts the high level / low level, and calculates the frequency of the ICR output, to obtain the difference between the actual frequencies of the two lasers. In addition, the frequency acquisition module is replaced by any hardware structure that can realize the acquisition of the frequency of the optical signal, but considering the overall design and cost, the structure given in the patent is adopted.

[0170] The master module sets the temperature variation of the laser according to the frequency acquisition data, so that the frequency of the ICR output can be reduced, that is, the frequency of the target DFB laser is closer to the reference DFB laser, thereby stabilizing the output frequency of the target DFB laser. Slowly reduce the ICR output signal frequency and stabilize it within 100MHz. When the laser frequency is locked within 100MHz, the MCU continues to collect and calculate the signal frequency, and keeps the frequency locked within 100MHz through frequency trimming.

[0171] The system reserves a USB interface in the master module, and the connected host computer is only used for data acquisition in the debugging stage. After debugging is completed, the host computer is not needed for normal operation of the system. After the system is started, the pre-set program will send information to the laser and the frequency acquisition module through the master MCU.

[0172] The oscilloscope is used for data acquisition in the debugging stage. After debugging is completed, the oscilloscope is not needed for normal operation of the system.

[0173] The frequency acquisition module 5 can also be provided with a display 55, which can be used to display laser frequency information in real time and can assist maintenance operations. The display can be replaced by any structure with display function, such as liquid crystal display (LCD), organic light-emitting diode display (OLED), micro display or other similar display device. The specific form can be selected according to the actual application requirement, without affecting the normal operation of the frequency stabilization system. The display has low cost and little effect on the overall cost.

[0174] In addition, referring to Figure 7 The specific process of the DFB laser frequency stabilization control method realized based on the above DFB laser frequency stabilization control system is as follows:

[0175] S100, calibrate the temperature frequency of the two DFB lasers, ensure that there is an overlapping part of the temperature frequency of the two lasers within the working temperature range of the TEC, and calculate the temperature frequency characteristics of the overlapping part.

[0176] The frequency characteristics and wavelength characteristics have completely correlated properties, and the wavelength control can be implemented in the form of frequency control. There is a direct inverse relationship between the wavelength λ and the frequency f of a laser beam, connected by the speed of light c.

[0177] By using the formula c = λ·f, conversion between wavelength and frequency can be conveniently performed.

[0178] Before starting the system, the temperature frequency characteristics of the two lasers need to be tested, and it is necessary to ensure that the frequency has an overlap within the working temperature.

[0179] The temperature frequency characteristic of the laser refers to that when the temperature of the laser changes, the output frequency of the laser will also shift, and the correlation characteristic between the temperature change amount and the frequency shift amount is the temperature frequency characteristic. The temperature frequency characteristic is obtained through testing and calculation.

[0180] Through testing, the temperature frequency data of the laser is obtained, and it is known that the temperature frequency characteristic of each laser can be quantified by a temperature wavelength change coefficient. According to actual testing, the temperature wavelength change coefficient of the DFB laser used in the present application can be 0.1 nm / ℃ (±0.02 nm / ℃).

[0181] S200, set the initial current and temperature of the laser, so that the output frequency of the reference DFB laser is located in the center area of the overlapping part, and the target DFB laser is located at a higher frequency.

[0182] Specifically, the constant current source is used to provide a constant current to the DFB laser to maintain the input current of the DFB laser at a predetermined constant value, thereby ensuring the stability of the laser output frequency. The temperature control keeps the temperature at a constant value or changes the temperature so that the laser output frequency changes, thereby adjusting the laser frequency according to the received signal.

[0183] The pre-set initial current and temperature can make the output frequency of the reference DFB laser located in the center area of the overlapping part, and the target DFB laser located at a higher frequency.

[0184] After the master control sets the current and temperature of the reference DFB laser and the target DFB laser, it will wait for a period of time, about 15 seconds, and then run the subsequent program. Keep the current and temperature of the reference DFB laser unchanged, change the temperature of the target DFB laser, set a fixed temperature interval, named first temperature step, unit: Celsius.

[0185] S300, continuously change the temperature of the target DFB laser by the first temperature step, so that its output frequency approaches the output frequency of the reference DFB laser, and collect the beat frequency frequency output by the ICR.

[0186] When the system is running, the lasers emitted by the two lasers are coherently detected by the ICR to obtain a signal with a beat frequency, and the beat frequency can be obtained after the frequency divider and the comparator. The reference DFB laser is connected to the SIG port of the ICR, and the current and temperature of the laser are fixed, that is, the frequency remains unchanged. The master control MCU continuously and slowly changes the temperature of the target DFB laser, thereby changing the frequency of the laser connected to the LO port of the coherent receiver, and the frequency acquisition module continuously and continuously calculates the signal frequency.

[0187] S400, judging whether the frequency difference at the two temperatures before and after the change of temperature conforms to the temperature-frequency characteristic.

[0188] The frequency difference refers to the difference between the two beat frequency frequencies collected by the frequency collection module before and after the temperature controlled temperature change by one step.

[0189] S500, calculating a second temperature step according to the temperature-frequency characteristic, determining the temperature adjustment direction according to the collected frequency, and continuously adjusting the temperature of the target DFB laser in small steps.

[0190] When the sampled frequency is greater than 100Mhz, the second temperature step is set to 0.008℃. When the sampled frequency is less than 100Mhz, the second temperature step is set to 0.001℃.

[0191] When the sampled frequency is greater than 100Mhz, the second temperature step is set to 0.008℃. When the sampled frequency is less than 100Mhz, the second temperature step is set to 0.001℃.

[0192] When the sampled frequency is less than 100Mhz, the second temperature step is set to 0.001℃. The reason is that the temperature control receives a 16-bit DAC analog signal, and 16-bit binary bits can represent integers between 0 and 65535. Therefore, the range of the digital signal transmitted by the laser MCU is an integer between 0 and 65535. The accuracy of this integer is about 0.001℃ when converted to temperature, which is calculated as follows:

[0193] set = (-26.7 * temperature + 1867) * B / Vref

[0194] temperature is the temperature to be set, in Celsius; set is the required temperature corresponding to the setting value, which is the decimal value of the digital signal transmitted by the laser MCU, ranging from 0 to 65535; B is 65535; Vref is the reference voltage, which is 2.5V, that is, 2500mV.

[0195] The variable of the formula is int and temperature; the formula is determined according to the measured temperature and the set value; through the formula and the required temperature value, the set value, that is, the digital signal converted into a decimal value required to be transmitted by the laser MCU, can be estimated and calculated.

[0196] Since the set value (set) is an integer, the minimum change is 1. According to the formula, when int changes by 1, temperature changes by approximately 0.001℃, so the precision of temperature control is about 0.001℃, that is, the minimum change range of temperature is about 0.001℃. The control algorithm can realize that the temperature control is adjusted by approximately the minimum 0.001℃ as the temperature step, but not exactly 0.001℃.

[0197] In short, the laser MCU transmits a 16-bit digital signal to the temperature control, that is, a 16-bit binary bit, which can represent an integer between 0 and 65535, so the range of the digital signal transmitted by the laser MCU is an integer between 0 and 65535. The minimum change of the integer is 1, which is converted to a temperature change of about 0.001℃. Therefore, the minimum change of temperature is about 0.001℃. In this case, the temperature step can be 0.001℃ and above, and 0.001℃ is preferred.

[0198] The temperature of the target DFB laser is set to the current temperature target plus a second temperature step, written as "Target-Step", and the temperature is reduced by a second temperature step. The sum of the five sampling frequencies is obtained by continuously sampling the frequency for five times, and is named as the down frequency sum, written as "SUM1". The temperature of the target DFB laser is set to the current temperature target plus a temperature step, written as "Target+Step", and the sum of the five sampling frequencies is obtained by continuously sampling the frequency for five times, and is named as the up frequency sum, written as "SUM2". SUM1 and SUM2 are compared, and Target is reset according to the comparison result of SUM1 and SUM. If SUM1 is small, the temperature target is set to the current temperature target minus a second temperature step; if SUM2 is small, the Target temperature is set to Target+Step.

[0199] When the sampled frequency is greater than 100Mhz, the second temperature step is set to 0.008℃; when the sampled frequency is less than 100Mhz, the second temperature step is set to 0.001℃, which is the minimum step of temperature adjustment.

[0200] When the sampled frequency is less than 100Mhz, that is, the beat frequency is reduced to within 100MHz, the MCU continues to continuously collect and calculate the signal frequency, and the loop continues, and the beat frequency is maintained within 100MHz by fine tuning.

[0201] The frequency stability feedback algorithm is combined with the frequency stabilization control device to realize the frequency stabilization of the target DFB laser. The frequency offset of the target DFB laser within a certain temperature change (10-60 DEG C) is not more than + / - 100 MHz.

[0202] That is, in the application examples described above, the principle is to collect the beat frequency and obtain the change amount, so as to obtain the frequency offset of the target DFB laser, and then perform feedback control. The development demand of coherent optical communication can be realized, the stability of the output frequency of the fiber laser can be automatically controlled, the influence of the frequency offset under the influence of temperature change on the output optical signal is reduced, and the transmission performance and stability of the coherent optical laser system are improved. The problem of insufficient frequency stability of the laser in coherent optical communication can be effectively solved, technical support is provided for realizing high-performance and high-reliability optical communication systems, and the further development and application of coherent optical communication technology are promoted.

[0203] The electronic device such as the main controller provided in the embodiment of the application can include a processor, a memory, a receiver and a transmitter. The processor is used to execute the DFB laser frequency stabilization control method mentioned in the above embodiment. The processor and the memory can be connected through a bus or other means, for example, the connection through the bus. The receiver can be connected with the processor and the memory through wired or wireless means.

[0204] The processor can be a central processing unit (CPU). The processor can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations thereof.

[0205] The memory is a non-transitory computer readable storage medium, which can be used to store non-transitory software programs, non-transitory computer executable programs and modules, such as the program instructions / modules corresponding to the DFB laser frequency stabilization control method in the embodiment of the application. The processor executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions and modules stored in the memory, that is, realizes the DFB laser frequency stabilization control method in the above method embodiment.

[0206] The memory can include a program storage area and a data storage area. The program storage area can store an operating system and applications required by at least one function. The data storage area can store data created by the processor and the like. In addition, the memory can include a high-speed random access memory and can also include a non-transitory memory such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid state memory device. In some embodiments, the memory can optionally include a memory that is remotely located with respect to the processor and can be connected to the processor through a network. Examples of the network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0207] The one or more modules are stored in the memory and, when executed by the processor, perform the DFB laser frequency stabilization control method in the embodiments.

[0208] In some embodiments of the present application, the user equipment can include a processor, a memory, and a transceiver unit that can include a receiver and a transmitter. The processor, the memory, the receiver, and the transmitter can be connected through a bus system. The memory is used to store computer instructions, and the processor is used to execute the computer instructions stored in the memory to control the transceiver unit to transceive signals.

[0209] As an implementation manner, the functions of the receiver and the transmitter in the present application can be implemented by a transceiver circuit or a transceiver dedicated chip. The processor can be implemented by a dedicated processing chip, a processing circuit, or a general-purpose chip.

[0210] As another implementation manner, the server provided by the embodiments of the present application can be implemented in the manner of a general-purpose computer. That is, program codes for implementing the functions of the processor, the receiver, and the transmitter are stored in the memory, and the general-purpose processor implements the functions of the processor, the receiver, and the transmitter by executing the codes in the memory.

[0211] The embodiments of the present application also provide a computer readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the aforementioned DFB laser frequency stabilization control method. The computer readable storage medium can be a tangible storage medium such as a random access memory (RAM), an internal memory, a read only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a floppy disk, a hard disk, a removable memory disk, a CD-ROM, or any other form of storage medium known in the technical field.

[0212] The embodiments of the present application also provide a computer program product including a computer program, which, when executed by a processor, implements the steps of the aforementioned DFB laser frequency stabilization control method.

[0213] Those of ordinary skill in the art will appreciate that the various illustrative components, systems and methods described in connection with the embodiments disclosed herein can be implemented as hardware, software, or both. The particular implementation is dependent on the specific application and design constraints imposed on the overall system. Skilled persons can implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application. When implemented in hardware, for example, the hardware can comprise an electronic circuit, an Application-Specific Integrated Circuit (ASIC), appropriate firmware, a plug-in card, a function card, etc. When implemented in software, the elements of the present application are the program or code segments to perform a particular task. The program or code segments can be stored in a machine-readable medium, or carried by a data signal in a carrier wave through a transmission medium or a communication link.

[0214] It is to be understood that the application is not limited to the particular configurations and processes described herein and shown in the figures. For simplicity, detailed descriptions of known methods are omitted. In the above embodiments, several specific steps are described and shown as examples. However, the method processes of the present application are not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order of the steps, after understanding the spirit of the present application.

[0215] In the present application, the features described and / or illustrated for one embodiment can be used in the same way or in a similar way in one or more other embodiments, and / or in combination with or instead of features of other embodiments.

[0216] The above description is merely illustrative of the application, and is not intended to limit the application. The embodiments of the application can be modified and changed in various ways by those skilled in the art, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A method for frequency stabilization control of a DFB laser, characterized in that, The method comprises: continuously changing the temperature of a target DFB laser so that the output frequency of the target DFB laser approaches a fixed value of the output frequency of a reference DFB laser, wherein the target DFB laser and the reference DFB laser both meet respective preset frequency range requirements; after each change of the temperature of the target DFB laser, the beat frequency between the reference DFB laser and the target DFB laser is collected respectively, and it is monitored in real time whether the frequency difference between the beat frequencies collected continuously for two times meets a preset temperature-frequency characteristic; if the frequency difference between the beat frequencies collected continuously for two times meets the temperature-frequency characteristic, the temperature of the target DFB laser is adjusted according to a feedback control algorithm so that the frequency offset of the target DFB laser meets a preset frequency stability condition; the preset frequency range requirement corresponding to the reference DFB laser comprises that the output frequency of the reference DFB laser is within an intermediate value range in a temperature-frequency overlap range; wherein the temperature-frequency overlap range is a frequency value overlap range between the output frequencies of the reference DFB laser and the target DFB laser respectively within a TEC working temperature range; the intermediate value range refers to a numerical range in which the difference from the intermediate value of the temperature-frequency overlap range is less than a first threshold value; the preset frequency range requirement corresponding to the target DFB laser comprises that the output frequency of the target DFB laser is within a high frequency range in the temperature-frequency overlap range, wherein the high frequency range is a numerical range in which the frequencies in the temperature-frequency overlap range are higher than the numerical values in the intermediate value range; Correspondingly, before the continuously changing the temperature of the target DFB laser so that the output frequency of the target DFB laser approaches the fixed value of the output frequency of the reference DFB laser, the method further comprises: based on a micro control unit corresponding to the reference DFB laser, the temperature and the applied current of the reference DFB laser are adjusted to an initial temperature and an initial current corresponding to the reference DFB laser respectively, so that the output frequency of the reference DFB laser is within the intermediate value range in the temperature-frequency overlap range, and the temperature and the applied current of the reference DFB laser are fixed so that the current output frequency of the reference DFB laser serves as the fixed value of the output frequency; and based on a micro control unit corresponding to the target DFB laser, the temperature and the applied current of the target DFB laser are adjusted to an initial temperature and an initial current corresponding to the target DFB laser respectively, so that the current output frequency of the target DFB laser is within the high frequency range in the temperature-frequency overlap range.

2. The DFB laser frequency stabilization control method of claim 1, wherein, The continuously changing the temperature of the target DFB laser so that the output frequency of the target DFB laser approaches the fixed value of the output frequency of the reference DFB laser comprises: The output frequency fixed value of the reference DFB laser is taken as an output frequency target of the target DFB laser, and the temperature of the target DFB laser is continuously changed by a preset first temperature step based on a micro control unit corresponding to the target DFB laser, so that the output frequency of the target DFB laser approaches the output frequency fixed value of the reference DFB laser.

3. The DFB laser frequency stabilization control method of claim 1, wherein, The step of collecting the beat frequency between the reference DFB laser and the target DFB laser after each change of the temperature of the target DFB laser includes: After each change of the temperature of the target DFB laser, the beat signal of the reference DFB laser and the target DFB laser collected by an integrated coherent receiver respectively connected to the reference DFB laser and the target DFB laser is controlled, wherein the integrated coherent receiver is used to collect the laser signals of the reference DFB laser and the target DFB laser respectively and convert the laser signals into electrical signals to generate corresponding beat signals after each change of the temperature of the target DFB laser, and the beat signals are transmitted to a frequency collection module; The beat frequency corresponding to the beat signal collected by the frequency collection module after each reception of the beat signal is received, wherein the beat frequency between the reference DFB laser and the target DFB laser is the frequency difference between the current output frequency of the reference DFB laser and the output frequency fixed value.

4. The DFB laser frequency stabilization control method of claim 1, wherein, The step of monitoring whether the frequency difference between the beat frequencies collected continuously twice satisfies a preset temperature-frequency characteristic includes: The frequency difference between the two beat frequencies collected continuously twice and the temperature difference between the temperatures applied to the target DFB laser when the two beat frequencies are collected respectively are monitored in real time to see whether they meet a preset temperature-frequency characteristic, wherein the temperature-frequency characteristic includes a preset curve representing the corresponding relationship between the frequency difference and the temperature difference of the target DFB laser.

5. The DFB laser frequency stabilization control method of claim 1, wherein, If the frequency difference between the beat frequencies collected continuously twice satisfies the temperature-frequency characteristic, the temperature of the target DFB laser is regulated according to a feedback control algorithm, so that the frequency offset of the target DFB laser satisfies a preset frequency stability condition, including: If the frequency difference between the beat frequencies collected continuously twice satisfies the temperature-frequency characteristic, the current temperature applied to the target DFB laser is set as a target temperature. A second temperature step is set according to the beat frequency currently corresponding to the target DFB laser, and a temperature value after the target temperature is reduced by one second temperature step is set as a first temperature, and a temperature value after the target temperature is increased by one second temperature step is set as a second temperature. A down-regulation step: the current temperature of the target DFB laser is regulated to the first temperature, and the beat frequencies between the reference DFB laser and the target DFB laser are continuously collected and added to obtain a corresponding down-regulation frequency sum. The up-regulation step: regulating the current temperature of the target DFB laser to the second temperature, and continuously collecting and summing the beat frequencies between the reference DFB laser and the target DFB laser to obtain corresponding up-regulation frequency sum; Comparing the down-regulation frequency sum and the up-regulation frequency sum; if the current down-regulation frequency sum is less than the up-regulation frequency sum, resetting the second temperature step according to the current corresponding beat frequency of the target DFB laser, and performing the down-regulation step; if the current down-regulation frequency sum is greater than the up-regulation frequency sum, resetting the second temperature step according to the current corresponding beat frequency of the target DFB laser, and performing the up-regulation step, so that the frequency offset of the target DFB laser meets the preset frequency stability condition, wherein the frequency stability condition includes that when the environmental temperature of the target DFB laser changes within a preset temperature range, the frequency offset of the target DFB laser also changes within a preset frequency range.

6. A DFB laser frequency stabilization control device, characterized by, Comprise: A temperature regulation module for continuously changing the temperature of a target DFB laser to make the output frequency of the target DFB laser close to a fixed value of the output frequency of a reference DFB laser, wherein the target DFB laser and the reference DFB laser both meet respective preset frequency range requirements; An acquisition and monitoring module for acquiring the beat frequency between the reference DFB laser and the target DFB laser after each change in the temperature of the target DFB laser, and monitoring in real time whether the frequency difference between the beat frequencies acquired continuously for two times meets a preset temperature-frequency characteristic; A feedback control module for regulating the temperature of the target DFB laser according to a feedback control algorithm if the frequency difference between the beat frequencies acquired continuously for two times meets the temperature-frequency characteristic, so that the frequency offset of the target DFB laser meets a preset frequency stability condition; The preset frequency range requirement corresponding to the reference DFB laser includes that the output frequency of the reference DFB laser is within an intermediate value range in a temperature-frequency overlap range; wherein the temperature-frequency overlap range is a frequency value overlap range between the output frequencies of the reference DFB laser and the target DFB laser within a TEC operating temperature range; the intermediate value range refers to a numerical range in which the difference between each value in the intermediate value range and the intermediate value of the temperature-frequency overlap range is less than a first threshold value; The preset frequency range requirement corresponding to the target DFB laser includes that the output frequency of the target DFB laser is within a high frequency range in the temperature-frequency overlap range, wherein the high frequency range is a numerical range in which each value in the high frequency range is higher than each value in the intermediate value range in the temperature-frequency overlap range; Correspondingly, before the temperature of the target DFB laser is continuously changed so that the output frequency of the target DFB laser approaches the fixed value of the output frequency of the reference DFB laser, the DFB laser frequency stabilization control device is further configured to perform the following: based on the micro control unit corresponding to the reference DFB laser, the temperature and the applied current of the reference DFB laser are respectively adjusted to the initial temperature and the initial current corresponding to the reference DFB laser, so that the output frequency of the reference DFB laser is in the middle value range of the temperature frequency overlap range, and the temperature and the applied current of the reference DFB laser are fixed, so that the current output frequency of the reference DFB laser is as the fixed value of the output frequency; and, based on the micro control unit corresponding to the target DFB laser, the temperature and the applied current of the target DFB laser are respectively adjusted to the initial temperature and the initial current corresponding to the target DFB laser, so that the current output frequency of the target DFB laser is in the high frequency range of the temperature frequency overlap range.

7. A DFB laser frequency stabilization control system, characterized in that, Comprising: a main controller, an integrated coherent receiver, a first laser device, a second laser device and a frequency acquisition module connected to the main controller respectively; the integrated coherent receiver is connected to the frequency acquisition module, the first laser device and the second laser device respectively; the main controller is configured to perform the DFB laser frequency stabilization control method of any one of claims 1 to 5; the first laser device is provided with a first micro control unit, a first digital to analog converter, a first temperature control unit, a first constant current source and the reference DFB laser, the first micro control unit is connected to the main controller and the first digital to analog converter respectively, the first digital to analog converter is connected to the first temperature control unit and the first constant current source respectively, the first temperature control unit and the first constant current source are connected to the reference DFB laser respectively, and the reference DFB laser is connected to the integrated coherent receiver; the second laser device is provided with a second micro control unit, a second digital to analog converter, a second temperature control unit, a second constant current source and the target DFB laser, the second micro control unit is connected to the main controller and the second digital to analog converter respectively, the second digital to analog converter is connected to the second temperature control unit and the second constant current source respectively, the second temperature control unit and the second constant current source are connected to the target DFB laser respectively, and the target DFB laser is connected to the integrated coherent receiver; wherein the first micro control unit is configured to adjust the first temperature control unit to change the temperature of the reference DFB laser and / or adjust the first constant current source to apply current to the reference DFB laser according to the control signal of the main controller; the second micro control unit is configured to adjust the second temperature control unit to change the temperature of the target DFB laser and / or adjust the second constant current source to apply current to the target DFB laser according to the control signal of the main controller; The integrated coherent receiver is configured to, after each change of the temperature of the target DFB laser, respectively collect the laser signals of the reference DFB laser and the target DFB laser, and convert the laser signals into corresponding beat signals, and transmit the beat signals to the frequency acquisition module; The frequency acquisition module is configured to, after each reception of the beat signal, acquire the beat frequency corresponding to the beat signal, and transmit the beat frequency to the main controller.

8. The DFB laser frequency stabilization control system of claim 7, wherein, The integrated coherent receiver is provided with a local oscillator light port and an optical carrier port, so that the integrated coherent receiver receives the laser signal emitted by the target DFB laser from the local oscillator light port, and receives the laser signal emitted by the reference DFB laser from the optical carrier port.

9. The DFB laser frequency stabilization control system of claim 7, wherein, The frequency acquisition module comprises an SMA connector, a frequency divider, a comparator and a counter connected in sequence; The SMA connector is configured to receive the beat signal transmitted by the integrated coherent receiver, and transmit the beat signal to the frequency divider; The frequency divider is configured to perform frequency division processing on the beat signal, and transmit the frequency-division-processed beat signal to the comparator; The comparator is configured to convert the frequency-division-processed beat signal into a binary signal, and transmit the binary signal to the counter; The counter is configured to perform level counting on the binary signal to obtain the corresponding beat frequency.

Images