Signal modulation device, signal modulation method, and laser light source system

Abstract

The present application provides a signal modulation device, which includes a sawtooth wave generation module, a trapezoidal wave generation module, a frequency addition module, and a modulation module. The sawtooth wave generation module is used to generate a target sawtooth wave signal. The trapezoidal wave generation module is used to generate a target trapezoidal wave signal. Here, the maximum frequency of the target sawtooth wave signal is the same as the step frequency of the target trapezoidal wave signal, and the ratio of the second period of the target trapezoidal wave signal to the first period of the target sawtooth wave signal is the same as the order of the target trapezoidal wave signal. The frequency addition module is used to generate a modulation wave signal based on the target sawtooth wave signal generated by the sawtooth wave generation module and the target trapezoidal wave signal generated by the trapezoidal wave generation module. The modulation module is used to load the modulation wave signal generated by the frequency addition module onto the light wave output by the laser to output a chirped light. Based on the present application, cyclic frequency shift can be performed on the electrical signal to expand to a high bandwidth, with high linearity, strong flexibility, and strong applicability.

Description

Technical Field

[0001] The present application relates to the technical field of lidar, and particularly relates to a signal modulation device, a signal modulation method, and a laser light source system. Background Art

[0002] At present, coherent lidar technology based on frequency modulated continuous wave (FMCW) can achieve higher detection sensitivity and accuracy. For example, the sensitivity of FMCW lidar is more than 10 times higher than that of a radar using direct time-of-flight detection. FMCW lidar can also effectively prevent the interference of background light and protect the human eye. The key device in FMCW lidar is a chirped laser. A chirped laser can be obtained through an internal modulation method or an external modulation method to provide a laser source for the FMCW lidar. Generally speaking, when modulating a chirped laser through the internal modulation method, the linearity of the frequency is poor, and a phase-locked loop circuit is required for feedback control, resulting in poor flexibility. When modulating a chirped laser through the external modulation method, optical devices (such as an optical frequency shifter) are needed to shift the frequency on the light to obtain a chirped linear light source, and the usage cost is relatively high. Summary of the Invention

[0003] The present application provides a signal modulation device, a signal modulation method, and a laser light source system, which can perform cyclic frequency shifting on an electrical signal to expand to a high bandwidth, with low cost, high linearity, strong flexibility, and wide applicability.

[0004] In a first aspect, the present application provides a signal modulation device, which includes a sawtooth wave generation module, a trapezoidal wave generation module, a frequency addition module, and a modulation module. The sawtooth wave generation module is used to generate a target sawtooth wave signal. Here, the sawtooth wave generation module may include a signal generator having the function of generating a sawtooth wave signal, such as a first arbitrary waveform generator or a first digital-to-analog converter. The trapezoidal wave generation module is used to generate a target trapezoidal wave signal, where the maximum frequency of the target sawtooth wave signal is the same as the step frequency of the target trapezoidal wave signal, and the ratio of the second period of the target trapezoidal wave signal to the first period of the target sawtooth wave signal is the same as the order of the target trapezoidal wave signal. The frequency addition module is used to generate a modulation wave signal based on the target sawtooth wave signal generated by the sawtooth wave generation module and the target trapezoidal wave signal generated by the trapezoidal wave generation module. The modulation module is used to load the modulation wave signal generated by the frequency addition module onto the light wave output by the laser to output a chirped light. In the present application, the trapezoidal wave generation module is used to perform cyclic frequency shift on the electrical signal to expand to a high bandwidth, so as to obtain a high-bandwidth chirped light that meets the requirements. Moreover, the parameters of the sawtooth wave generation module and the trapezoidal wave generation module can be adjusted respectively to obtain different modes of chirped light, with high linearity, strong flexibility, and strong applicability.

[0005] Combined with the first aspect, in a first possible implementation manner, the bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period. The first period of the target sawtooth wave signal is determined by the maximum frequency of the target sawtooth wave signal, the modulation bandwidth, and the modulation period. In the signal modulation device provided by the present application, the modulation bandwidth and modulation period of the chirped light set by the user and the maximum frequency of the target sawtooth wave signal can be collected, and the first period of the target sawtooth wave signal can be calculated. Here, the maximum frequency and the first period of the target sawtooth wave signal can be subsequently used by the sawtooth wave generation module to generate the target sawtooth wave signal. In addition, the maximum frequency and the first period of the target sawtooth wave signal can be adjusted respectively to generate different target sawtooth wave signals, and finally different modes of chirped light can be obtained, with strong flexibility.

[0006] In combination with the first aspect, in the second possible implementation, the bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period. The maximum frequency of the target sawtooth wave signal is determined by the first period of the target sawtooth wave signal, the modulation bandwidth, and the modulation period. In the signal modulation device provided in the present application, the modulation bandwidth and modulation period of the chirped light set by the user, and the first period of the target sawtooth wave signal can be collected, and the maximum frequency of the target sawtooth wave signal can be calculated. Here, the maximum frequency and the first period of the target sawtooth wave signal can be used subsequently by the sawtooth wave generation module to generate the target sawtooth wave signal. Additionally, different target sawtooth wave signals can be generated by adjusting the maximum frequency and the first period of the target sawtooth wave signal, and ultimately different modes of chirped light can be obtained, with strong flexibility.

[0007] In combination with the first aspect, in the third possible implementation, the bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period. The second period of the target trapezoidal wave signal is determined by the modulation period, the step frequency of the target trapezoidal wave signal is determined by the maximum frequency of the target sawtooth wave signal, and the number of steps of the target trapezoidal wave signal is determined by the modulation bandwidth and the maximum frequency of the target sawtooth wave signal. In the signal modulation device provided in the present application, the modulation bandwidth and modulation period of the chirped light set by the user, and the maximum frequency of the target sawtooth wave signal can be collected, and based on these three parameters, the second period, the step frequency, and the number of steps of the target trapezoidal wave signal can be directly or indirectly calculated. Here, the second period, the step frequency, and the number of steps of the target trapezoidal wave signal can be used subsequently by the trapezoidal wave generation module to generate the target trapezoidal wave signal. Additionally, different target trapezoidal wave signals can be generated by adjusting the second period, the step frequency, and the number of steps of the target trapezoidal wave signal, and ultimately different modes of chirped light can be obtained, with strong flexibility.

[0008] In combination with the first aspect, in the fourth possible implementation, the bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period. The second period of the target trapezoidal wave signal can be determined by the modulation period, the number of steps of the target trapezoidal wave signal is determined by the modulation period and the first period of the target sawtooth wave signal, and the step frequency of the target trapezoidal wave signal is determined by the modulation bandwidth and the number of steps. In the signal modulation device provided in the present application, the modulation bandwidth and modulation period of the chirped light set by the user, and the first period of the target sawtooth wave signal can be collected, and based on these three parameters, the second period, the step frequency, and the number of steps of the target trapezoidal wave signal can be directly or indirectly calculated. Here, the second period, the step frequency, and the number of steps of the target trapezoidal wave signal can be used subsequently by the trapezoidal wave generation module to generate the target trapezoidal wave signal. Additionally, different target trapezoidal wave signals can be generated by adjusting the second period, the step frequency, and the number of steps of the target trapezoidal wave signal, and ultimately different modes of chirped light can be obtained, with high linearity and strong flexibility.

[0009] Combined with any one of the first to the fourth possible implementation manners of the first aspect, in the fifth possible implementation manner, the trapezoidal wave generation module includes a signal generator, a controller, a first mixer, and a first filter. The signal generator is used to generate a first input signal, where the frequency of the first input signal is a constant frequency that is the same as the step frequency. For example, the signal generator may include a second arbitrary waveform generator or a second digital-to-analog converter. The controller is used to output a second input signal for generating any stepped wave signal of the target trapezoidal wave signal to the first mixer within a time duration T based on the input of the first filter. Wherein, the second input signal for generating any stepped wave signal of the target trapezoidal wave signal may be the previous stepped wave signal of any stepped wave signal. Here, the time duration T is determined by the order and the second period. For example, the time duration T may be the same as the ratio of the order to the second period. The first mixer is used to perform time-domain multiplication on the first input signal input by the signal generator and the second input signal input by the controller and output a first output signal to the first filter. The first output signal may include a first difference frequency signal and a first sum frequency signal. Here, the first output signal may be subsequently used to determine any stepped wave signal. The first filter is used to filter out the first difference frequency signal in the first output signal input by the first mixer and use the first sum frequency signal in the first output signal as any stepped wave signal with a time duration of T, and finally output a target trapezoidal wave signal with the above-mentioned second period, step frequency, and order.

[0010] In the signal modulation device provided in the present application, the signal generator may input a first input signal with a constant frequency (such as the step frequency) to the first mixer. The controller does not directly use the input of the first filter as the second input signal, but outputs the second input signal to the first mixer within a time duration T based on the input of the first filter. The controller can control the mixing period of the first mixer (i.e., the second period of the target trapezoidal wave signal) by controlling the period of the second input signal. At this time, the first mixer can perform time-domain multiplication on the first input signal and the second input signal to input a first output signal to the first filter. The first filter can filter out the first difference frequency signal in the first output signal input by the first mixer to use the first sum frequency signal as any stepped wave signal with a time duration of T, and finally output the target trapezoidal wave signal, so that cyclic frequency shift can be realized electrically through the first mixer, which can be extended to high bandwidth, is flexibly adjustable, and has strong applicability.

[0011] Combined with the fifth possible implementation manner of the first aspect, in the sixth possible implementation manner, the second input signal output by the controller to the first mixer within the first time period T of the second period is 0. For example, the second input signal of the controller within the first time period T can be made 0 (i.e., the signal frequency of the second input signal is 0) by disconnecting the circuit (such as the circuit between the controller and the first filter), indicating that the controller does not input a signal to the first mixer at this time. The second input signal output by the controller to the first mixer within any time period T after the first time period T of the second period is the output signal of the first filter within the previous time period T of any time period T, indicating that the signal frequency of the second input signal of the controller within any time period T is the same as the signal frequency of the output signal of the first filter within the previous time period T of any time period T. In the signal modulation device provided in the present application, the controller can control the mixing period of the first mixer (the mixing period here is the same as the second period of the target trapezoidal wave signal) by controlling the presence or absence of the second input signal within different time periods T of the second period, so that different target trapezoidal wave signals can be generated for different second periods, with strong flexibility and greater applicability.

[0012] Combined with the sixth possible implementation manner of the first aspect, in the seventh possible implementation manner, since the second input signal output by the controller to the first mixer within the first time period T of the second period is 0, that is, there is no second input signal at this time, and only the signal generator inputs the first input signal to the first mixer, the first stepped wave signal of the target trapezoidal wave signal is the output signal of the first filter within the first time period T of the second period, and the output signal of the first filter within the first time period T is the same as the first input signal within the first time period T. In the signal modulation device provided in the present application, the first stepped wave signal of the target trapezoidal wave signal is generated based on the first input signal, and all other trapezoidal wave signals after the first stepped wave signal are generated based on the first input signal and the second input signal, and finally the target trapezoidal wave signal is obtained, with high linearity and greater applicability.

[0013] Combined with any one of the first to seventh possible implementation manners of the first aspect, in the eighth possible implementation manner, the frequency addition module may include a second mixer and a second filter. The second mixer is configured to perform time-domain multiplication on the target sawtooth wave signal and the target trapezoidal wave signal, and output a second output signal. Wherein, the second output signal may include a second difference frequency signal and a second sum frequency signal, and the second output signal here can be subsequently used to determine the modulation wave signal. The second filter is configured to filter out the second difference frequency signal in the second output signal input by the second mixer to obtain a second sum frequency signal, and output the second sum frequency signal as the modulation wave signal. In the signal modulation device provided in this application, the second mixer performs time-domain multiplication on the target sawtooth wave signal and the target trapezoidal wave signal to input the second output signal to the second filter, and the second filter filters out the second difference frequency signal therein and retains the second sum frequency signal, thereby realizing frequency addition of the target sawtooth wave signal and the target trapezoidal wave signal to obtain a modulation wave signal, and finally loading the modulation wave signal on the light wave output by the laser to output a high-bandwidth chirped light, with stronger applicability.

[0014] Combined with any one of the first to eighth possible implementation manners of the first aspect, in the ninth possible implementation manner, the chirped light may be any one of a chirped light with one slope, a chirped light with at least two slopes, or a triangular chirped light. In the signal modulation device provided in this application, the parameters of the sawtooth wave generation module and the trapezoidal wave generation module can be adjusted respectively, so as to obtain different modes of chirped light, with high linearity, strong flexibility, and stronger applicability.

[0015] In a second aspect, this application provides a signal modulation method, which is applicable to the signal modulation device provided in any one of the first to ninth possible implementation manners of the first aspect above. In this method, the signal modulation device may generate a target sawtooth wave signal and generate a target trapezoidal wave signal, wherein the maximum frequency of the target sawtooth wave signal is the same as the step frequency of the target trapezoidal wave signal, and the ratio of the second period of the target trapezoidal wave signal to the first period of the target sawtooth wave signal is the same as the order of the target trapezoidal wave signal. After generating the target sawtooth wave signal and the target trapezoidal wave signal, the signal modulation device may generate a modulation wave signal according to the target sawtooth wave signal and the target trapezoidal wave signal, and load the modulation wave signal on the light wave output by the laser to obtain chirped light.

[0016] Combined with the second aspect, in the first possible implementation manner, the bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period. The first period of the target sawtooth wave signal is determined by the maximum frequency of the target sawtooth wave signal, the modulation bandwidth, and the modulation period.

[0017] In combination with the second aspect, in a second possible implementation, the bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period; the maximum frequency of the target sawtooth signal is determined by the first period of the target sawtooth signal, the modulation bandwidth, and the modulation period.

[0018] In combination with the second aspect, in a third possible implementation, the bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period. The second period of the target trapezoidal wave signal is determined by the modulation period, the step frequency of the target trapezoidal wave signal is determined by the maximum frequency of the target sawtooth signal, and the number of steps of the target trapezoidal wave signal is determined by the modulation bandwidth and the maximum frequency of the target sawtooth signal.

[0019] In combination with the second aspect, in a fourth possible implementation, the bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period. The second period of the target trapezoidal wave signal is determined by the modulation period, the number of steps of the target trapezoidal wave signal is determined by the modulation period and the first period of the target sawtooth signal, and the step frequency of the target trapezoidal wave signal is determined by the modulation bandwidth and the number of steps.

[0020] In combination with any one of the second aspect to the fourth possible implementation of the second aspect, in a fifth possible implementation, the above signal modulation device acquires a first input signal, generates a first stepped wave signal with a duration of T based on the first input signal, and the frequency of the first input signal is the same as the step frequency; based on the first input signal and a second input signal for generating any stepped wave signal after the first stepped wave signal, generates any stepped wave signal with a duration of T, where the second input signal for generating any stepped wave signal is the previous stepped wave signal of any stepped wave signal, and the duration T is determined by the number of steps and the second period; generates a target trapezoidal wave signal with the number of steps based on each stepped wave signal.

[0021] In combination with the fifth possible implementation of the second aspect, in a sixth possible implementation, the above signal modulation device can obtain the second input signal for generating any stepped wave signal based on the previous stepped wave signal of any stepped wave signal; perform time-domain multiplication on the first input signal and the second input signal for generating any stepped wave signal after the first stepped wave signal within the duration T to obtain a first output signal for generating any stepped wave signal, and the first output signal includes a first difference frequency signal and a first sum frequency signal; filter out the first difference frequency signal in the first output signal to obtain the first sum frequency signal in the first output signal, and use the first sum frequency signal in the first output signal as any stepped wave signal with a duration of T.

[0022] Combined with the second aspect to the sixth possible implementation manners of the second aspect, in the seventh possible implementation manner, the above signal modulation device can perform time-domain multiplication on the target sawtooth wave signal and the target trapezoidal wave signal to output a second output signal, and the second output signal includes a second difference frequency signal and a second sum frequency signal; filter out the second difference frequency signal in the second output signal to obtain the second sum frequency signal, and use the second sum frequency signal as the modulation wave signal.

[0023] In a third aspect, the present application provides a laser light source system, which includes a laser and the signal modulation device provided by any one of the first aspect to the ninth possible implementation manners of the first aspect.

[0024] In the present application, the signal modulation device can realize cyclic frequency shift on the electrical signal through the trapezoidal wave generation module to expand to a high bandwidth, so as to obtain a high-bandwidth linearly chirped light that meets the requirements, with lower cost. At the same time, the parameters of the sawtooth wave generation module and the trapezoidal wave generation module can be adjusted respectively to obtain linearly chirped light of different modes, with high linearity, strong flexibility, and strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of an application scenario of the signal modulation device provided by the present application;

[0026] Figure 2 is a schematic structural diagram of the signal modulation device provided by the present application;

[0027] Figure 3 is a schematic diagram of the working principle of the signal modulation device provided by the present application;

[0028] Figure 4 is another schematic structural diagram of the signal modulation device provided by the present application;

[0029] Figure 5 is a schematic diagram of the working principle of the trapezoidal wave generation module provided by the present application to generate the target trapezoidal wave signal;

[0030] Figure 6 is a schematic diagram of the working principle of the frequency addition module provided by the present application to generate the modulation wave signal;

[0031] Figure 7 is another schematic diagram of the working principle of the signal modulation device provided by the present application;

[0032] Figure 8 is yet another schematic diagram of the working principle of the signal modulation device provided by the present application;

[0033] Figure 9 is a schematic structural diagram of the laser light source system provided by the present application;

[0034] Figure 10 It is a schematic flow diagram of the signal modulation method provided by this application. Detailed implementation manners

[0035] A lidar (light detection and ranging, which can be abbreviated as Lidar) is a radar system that detects the position, speed and other characteristic quantities of a target by emitting laser beams. Generally speaking, a lidar may include a laser, a transmitting system, a receiving system, an optical system, a signal processing system and a display system. The working principle of a lidar is that the transmitting system generates a detection signal and emits the detection signal (such as a laser beam with a certain power) to the target. The echo reflected by the target (such as the target echo) enters the signal processing system after being received by the receiving system. The signal processing system compares the echo reflected by the target with the emitted detection signal, and at the same time, after signal processing, relevant information of the target is obtained, such as parameters of the target (such as an aircraft and a missile) like distance, azimuth, altitude, speed, attitude and shape, so as to detect, track and identify targets such as aircraft and missiles.

[0036] The signal modulation device provided by this application is applicable to various application fields such as the industrial field (such as material processing and measurement control), the medical field (such as treatment and diagnosis), the commercial field, the scientific research field (such as lidar), the information field and the military field, which can be specifically determined according to the actual application scenario and are not limited herein. The signal modulation device provided by this application can be combined with other disciplines to form multiple application technology fields, such as optoelectronic technology, laser medicine and photon biology, laser processing technology, laser detection and metrology technology, laser holography technology, laser spectral analysis technology, nonlinear optics, ultrafast laser science, laser chemistry, quantum optics, lidar, laser guidance, laser isotope separation, laser controlled nuclear fusion, laser weapons, etc., which can be specifically determined according to the actual application scenario and are not limited herein. For example, the signal modulation device provided by this application is applicable to modulating the signal output by a laser to output a linearly frequency-modulated light, and further providing a linearly frequency-modulated light source (such as an FMCW fast frequency-sweeping light source) for a lidar (such as an FMCW lidar).

[0037] The signal modulation device provided by this application includes a sawtooth wave generation module, a trapezoidal wave generation module, a frequency addition module, and a modulation module. The sawtooth wave generation module can generate a target sawtooth wave signal based on the maximum frequency and the first period of the sawtooth wave signal. The trapezoidal wave generation module can generate a target trapezoidal wave signal based on the order of the trapezoidal wave signal, the step frequency, and the second period. The frequency addition module can generate a modulation wave signal based on the target sawtooth wave signal generated by the sawtooth wave generation module and the target trapezoidal wave signal generated by the sawtooth wave generation module. The modulation module can load the modulation wave signal generated by the frequency addition module onto the light wave output by the laser to output a linearly frequency-modulated light. In the signal modulation device provided by this application, cyclic frequency shift can be performed on the electrical signal through the trapezoidal wave generation module to expand to a high bandwidth, and the modulation wave signal can be loaded onto the light wave output by the laser through the modulation module to output a high-bandwidth linearly frequency-modulated light, which has high linearity, is flexibly adjustable, and has strong applicability. The signal modulation device provided by this application can be adapted to different application scenarios. For example, in the application scenarios of lidar detection, lidar tracking, or lidar recognition, the signal modulation device can provide a linearly frequency-modulated light source for the lidar in these application scenarios, so that the lidar can realize the functions of detecting, tracking, and recognizing targets based on the linearly frequency-modulated light source. This application will be described by taking the lidar detection application scenario (such as the airborne lidar detection application scenario) as an example.

[0038] See Figure 1 , Figure 1 is a schematic diagram of the application scenario of the signal modulation device provided by this application. In the airborne lidar detection application scenario, the signal modulation device can provide a linearly frequency-modulated light source for the airborne lidar, and the airborne lidar can perform radar scanning through this linearly frequency-modulated light source. Airborne lidar technology integrates a laser ranging device, a global navigation satellite system (GNSS) device, and an inertial navigation system (INS) device, uses a flight platform (such as an aircraft) as a carrier, performs radar scanning on the ground through the above-mentioned airborne lidar, records information such as the attitude, position, and reflection intensity of the target, obtains three-dimensional information of the ground surface, and processes the attitude, position, and reflection intensity of the target and the three-dimensional information of the ground surface to obtain the required spatial information technology. Such as Figure 1As shown, before the airborne lidar measures the terrain, several measurement stations need to be arranged in the terrain area to be measured. The airborne lidar can scan the terrain area to be measured at each measurement station, receive all echo signals (such as measurement data) reflected from the terrain area to be measured at each measurement station, and splice the measurement data (such as the distance of the terrain surface) corresponding to each measurement station in the same coordinate system to obtain the terrain map of the terrain area to be measured.

[0039] The following will be combined with Figures 2 to 8 to exemplify and explain the signal modulation device provided by this application and its working principle.

[0040] See Figure 2 , Figure 2 is a schematic structural diagram of the signal modulation device provided by this application. As Figure 2 shown, the signal modulation device may include a sawtooth wave generation module 10, a trapezoidal wave generation module 20, a frequency addition module 30, and a modulation module 40. The sawtooth wave generation module 10 can generate a target sawtooth wave signal based on the maximum frequency and the first period of the sawtooth wave signal. The trapezoidal wave generation module 20 can generate a target trapezoidal wave signal based on the order of the trapezoidal wave signal, the step frequency, and the second period. The frequency addition module 30 can generate a modulation wave signal based on the target sawtooth wave signal generated by the sawtooth wave generation module and the target trapezoidal wave signal generated by the trapezoidal wave generation module. The modulation module 40 can load the modulation wave signal generated by the frequency addition module onto the light wave output by the laser to output a linearly frequency-modulated light. For the convenience of description, the working principle of the signal modulation device will be described below by taking the sawtooth wave generation module 10, the trapezoidal wave generation module 20, the frequency addition module 30, and the modulation module 40 as examples, and will not be elaborated hereinafter.

[0041] See Figure 3 , Figure 3 is a schematic working principle diagram of the signal modulation device provided by this application.

[0042] In some feasible embodiments, the sawtooth wave generation module 10 can collect the modulation bandwidth of the chirped light set by the user (the modulation bandwidth here can be expressed as NΔf, where N is a positive integer), the modulation period of the chirped light (the modulation period here can be expressed as NT), and the maximum frequency of the sawtooth wave signal (the maximum frequency here can be expressed as f1) through the sawtooth wave parameter input interface, and calculate the first period T1 of the sawtooth wave signal, that is, T1 = NT / (NΔf / f1) = NT / (NΔf / Δf) = NT / N = T. The sawtooth wave generation module 10 can collect the modulation bandwidth NΔf, the modulation period NT, and the first period T1 of the sawtooth wave signal (such as T1 = T) set by the user through the sawtooth wave parameter input interface, and calculate the maximum frequency f1 of the sawtooth wave signal, that is, f1 = NΔf / (NT / T1) = NΔf / (NT / T) = NΔf / N = Δf. Optionally, the sawtooth wave generation module 10 can also directly call the known modulation bandwidth NΔf, modulation period NT, and the maximum frequency f1 of the sawtooth wave signal (such as f1 = Δf) from the signal parameter library, and calculate the first period T1 of the sawtooth wave signal (that is, T1 = T); or the sawtooth wave generation module 10 can also directly call the known modulation bandwidth NΔf, modulation period NT, and the first period T1 of the sawtooth wave signal (such as T1 = T) from the signal parameter library, and calculate the maximum frequency f1 of the sawtooth wave signal (that is, f1 = Δf). The signal parameter library here can contain signal parameters stored or configured by the user. Optionally, the sawtooth wave generation module 10 can also directly collect the maximum frequency f1 of the sawtooth wave signal (that is, f1 = Δf) and the first period T1 of the sawtooth wave signal (that is, T1 = T) set by the user through the sawtooth wave parameter input interface. It can be understood that the collection or calculation process of the maximum frequency and the first period of the sawtooth wave signal here can be specifically determined according to the actual application scenario, and is not limited here.

[0043] Further, after the sawtooth wave generation module 10 collects or calculates the first period T1 and the maximum frequency f1 of the sawtooth wave signal, it can generate a target sawtooth wave signal as shown in Figure 3 Figure 3a. From Figure 3 the target sawtooth wave signal shown in Figure 3a, it can be obtained that the maximum frequency of the target sawtooth wave signal in each first period T1 (such as 0~T, T~2T,..., or (N - 1)T~NT in the figure) is the maximum frequency f1 (such as Δf in the figure). At the same time, from Figure 3The target sawtooth wave signal shown in Fig. 3a can still be obtained. The initial phases of the target sawtooth wave signals generated by the sawtooth wave generation module 10 in different first periods T1 are the same, the signal frequency repeats at the first period T1, and the signal frequency within the same period T1 changes linearly. The subsequent target sawtooth wave signal can generate a modulation wave signal. The maximum frequency of the target sawtooth wave signal is f1, and f1 = Δf. The period of the target sawtooth wave signal is the first period T1, and T1 = T. It can be understood that the signal frequency f'(t) of the target sawtooth wave signal generated by the sawtooth wave generation module 10 within the first period T1 can be as shown in the following formula (1):

[0044]

[0045] Where f1 is the maximum frequency of the target sawtooth wave signal, and f1 = Δf; T1 is the first period of the target sawtooth wave signal, and T1 = T; t is time; n is the number of the first periods T1 (T1 = T); NT is the modulation period; k is the number of modulation periods; n is an integer greater than or equal to 0; k is an integer greater than or equal to 0. Here, t can satisfy the following conditions: nT + kNT < t ≤ (n + 1)T + kNT, n < N.

[0046] In some feasible embodiments, the trapezoidal wave generation module 20 can collect the modulation bandwidth NΔf, modulation period NT, and the maximum frequency f1 of the sawtooth wave signal set by the user through the trapezoidal wave parameter input interface, calculate the second period of the trapezoidal wave signal (the second period here can be expressed as T2, i.e., T2 = NT), the step frequency of the trapezoidal wave signal (the step frequency here can be expressed as f2, i.e., f2 = f1 = Δf), and the order of the trapezoidal wave signal (the order here can be expressed as N1, i.e., N1 = NΔf / f1 = NΔf / Δf = N). The trapezoidal wave generation module 20 can collect the modulation bandwidth NΔf, modulation period NT, and the first period T1 of the sawtooth wave signal set by the user through the trapezoidal wave parameter input interface, and calculate the second period T2 of the trapezoidal wave signal (i.e., T2 = NT), the order N1 of the trapezoidal wave signal (i.e., N1 = NT / T1 = NT / T = N), and the step frequency f2 of the trapezoidal wave signal (i.e., f2 = NΔf / N1 = NΔf / N = Δf). Optionally, the trapezoidal wave generation module 20 can also directly call the known modulation bandwidth NΔf, modulation period NT, and the maximum frequency f1 of the sawtooth wave signal (such as f1 = Δf) from the above signal parameter library, calculate the second period T2 of the trapezoidal wave signal (i.e., T2 = NT), the step frequency f2 of the trapezoidal wave signal (i.e., f2 = f1 = Δf), and the order N1 of the trapezoidal wave signal (i.e., N1 = N); or the trapezoidal wave generation module 20 can also directly call the known modulation bandwidth NΔf, modulation period NT, and the first period T1 of the sawtooth wave signal (such as T1 = T) from the above signal parameter library, calculate the second period T2 of the trapezoidal wave signal (i.e., T2 = NT), the order N1 of the trapezoidal wave signal (i.e., N1 = N), and the step frequency f2 of the trapezoidal wave signal (i.e., f2 = Δf). Optionally, the trapezoidal wave generation module 20 can also directly collect the second period T2 of the trapezoidal wave signal (i.e., T2 = NT), the order N1 of the trapezoidal wave signal (i.e., N1 = N), and the step frequency f2 of the trapezoidal wave signal (i.e., f2 = Δf) configured by the user through the trapezoidal wave parameter input interface. The specific process of collecting or calculating the order, step frequency, and second period of the trapezoidal wave signal here can be determined according to the actual application scenario and is not limited here.

[0047] Further, after the trapezoidal wave generation module 20 collects or calculates the order N1, step frequency f2, and second period T2 of the trapezoidal wave signal, it can generate a target trapezoidal wave signal as shown in Figure 3 Figure 3b. Figure 3The target trapezoidal wave signal shown in Fig. 3b can be obtained. In the period of 0 to NT, in the time period of 0 to T, the signal frequency of the target trapezoidal wave signal is Δf, in the time period of T to 2T, the signal frequency of the target trapezoidal wave signal is 2Δf, …, in the time period of (N - 1)T to NT, the signal frequency of the target trapezoidal wave signal is NΔf. It can be understood that the subsequent target trapezoidal wave signal here can generate a modulation wave signal, and the step frequency of the target trapezoidal wave signal is f2, and f2 = Δf, the period of the target trapezoidal wave signal is the second period T2, and T2 = NT. It can be understood that the trapezoidal wave generation module 20 outputs the signal frequency f″(t) of the target trapezoidal wave signal in the second period T2 (T2 = NT) as shown in the following formula (2):

[0048] f″(t) = (n + 1)f2 = (n + 1)f1 = (n + 1)Δf, (2)

[0049] Wherein, f2 is the step frequency of the target trapezoidal wave signal, and f2 = f1 = Δf, f1 is the maximum frequency of the target sawtooth wave signal, n is the number of the first period T1 (T1 = T) of the target sawtooth wave signal, and t is time. Here, t can satisfy the following conditions: nT + kNT < t ≤ (n + 1)T + kNT, n < N.

[0050] In some feasible embodiments, the frequency addition module 30 can be based on the target sawtooth wave signal shown in Figure 3 Fig. 3a generated by the sawtooth wave generation module 10, and the target trapezoidal wave signal shown in Figure 3 Fig. 3b generated by the trapezoidal wave generation module 20, to generate the modulation wave signal shown in Figure 3 Fig. 3c. From the modulation wave signal shown in Figure 3 Fig. 3c, it can be obtained that in the modulation period of 0 to NT, in the range of 0 to NT, the minimum signal frequency of the modulation wave signal is Δf, the maximum signal frequency of the modulation wave signal is (N + 1)Δf, indicating that the bandwidth of the modulation wave signal in the range of 0 to NT is NΔf (i.e., (N + 1)Δf - Δf = NΔf), and the signal frequency f″′(t) of the modulation wave signal changes linearly in each modulation period NT. It can be understood that the frequency addition module 30 can determine the modulation wave signal according to the signal frequency f′(t) of the target sawtooth wave signal and the signal frequency f″(t) of the target trapezoidal wave signal in each modulation period NT, and the signal frequency f″′(t) of the modulation wave signal is as shown in the following formula (3):

[0051]

[0052] Among them, f1 is the maximum frequency of the target sawtooth wave signal, and f1 = Δf; T1 is the first period of the target sawtooth wave signal, and T1 = T; t is time; n is the number of the first periods T1 (T1 = T) of the target sawtooth wave signal; NT is the modulation period; k is the number of modulation periods; f2 is the step frequency of the target trapezoidal wave signal, and f2 = f1 = Δf. Here, t can satisfy the following conditions: nT + kNT < t ≤ (n + 1)T + kNT, n < N.

[0053] In some feasible embodiments, the modulation module 40 may load the modulation wave signal generated by the frequency addition module 30, such as Figure 3 shown in 3c, onto the light wave output by the laser, such as Figure 3 shown in 3d, and output chirped light, such as Figure 3 shown in 3e. From the light wave shown in Figure 3 3d, it can be obtained that the laser can output a light wave with a fixed frequency (such as a light wave with a frequency of f0), and f 0 (t) represents the frequency of the light wave, and f 0 (t) is constantly equal to f0. From the chirped light shown in 3e, it can be obtained that in the modulation period of 0 to NT, within the time of 0 to NT, the minimum signal frequency of the chirped light is f0 + Δf, and the maximum signal frequency of the chirped light is f0 + (N + 1)Δf, indicating that the bandwidth of the chirped light within 0 to NT is NΔf (that is, f0 + (N + 1)Δf - (f0 + Δf) = NΔf), that is, chirped light with a modulation bandwidth of NΔf can be obtained. It can be understood that the modulation module 40 can determine the signal frequency f(t) of the chirped light according to the signal frequency f″′(t) of the modulation wave signal within each modulation period NT and the signal frequency f 0 (t) of the light wave, and the signal frequency f(t) of the chirped light is as shown in the following formula (4):

[0054]

[0055] Among them, f0 is the signal frequency of the light wave, f1 is the maximum frequency of the target sawtooth wave signal, and f1 = Δf; T1 is the first period of the target sawtooth wave signal, and T1 = T; t is time; n is the number of the first periods T1 (T1 = T) of the target sawtooth wave signal; NT is the modulation period; k is the number of modulation periods; f2 is the step frequency of the target trapezoidal wave signal, and f2 = f1 = Δf. Here, t can satisfy the following conditions: nT + kNT < t ≤ (n + 1)T + kNT, n < N.

[0056] Further, please refer to Figure 4 , Figure 4 which is another structural schematic diagram of the signal modulation device provided by the present application.

[0057] As Figure 4 shown, in some feasible embodiments, as Figure 2 shown, the sawtooth wave generation module 10 may include a signal generator having the function of generating a sawtooth wave signal, such as a first arbitrary waveform generator or a first digital-to-analog converter. For the convenience of description, hereinafter, the first arbitrary waveform generator or the first digital-to-analog converter will be taken as an example to illustrate the generation process of the target sawtooth wave signal, and details will not be repeated hereinafter.

[0058] In some feasible embodiments, the sawtooth wave generation module 10 includes a first arbitrary waveform generator, which can collect or calculate the maximum frequency f1 (such as f1 = Δf) and the first period T1 (such as T1 = T) of the sawtooth wave signal, and output the target sawtooth wave signal according to the maximum frequency f1 and the first period T1 of the sawtooth wave signal, with strong flexibility. Optionally, the sawtooth wave generation module 10 includes a first digital-to-analog converter, which can collect or calculate the maximum frequency f1 (such as f1 = Δf) and the first period T1 (such as T1 = T) of the sawtooth wave signal, and generate the target sawtooth wave signal according to the maximum frequency f1 and the first period T1 of the sawtooth wave signal. It can be understood that the above sawtooth wave parameter input interface can be the device interface of the first arbitrary waveform generator or the first digital-to-analog converter. Thus, compared with generating the target sawtooth wave signal through the first arbitrary waveform generator, generating the target sawtooth wave signal through the first digital-to-analog converter has lower cost and stronger adaptability.

[0059] In some feasible embodiments, after the trapezoidal wave generation module 20 collects or calculates the order N1 (i.e., N1 = N), the step frequency f2 (i.e., f2 = f1 = Δf), and the second period T2 (i.e., T2 = NT) of the trapezoidal wave signal, it can generate the target trapezoidal wave signal based on the order N1 (i.e., N1 = N), the step frequency f2 (i.e., f2 = f1 = Δf), and the second period T2 (i.e., T2 = NT) of the trapezoidal wave signal.

[0060] In some feasible embodiments, as Figure 2 shown, the trapezoidal wave generation module 20 may include a signal generator, a first mixer, a first filter, and a controller as Figure 4 shown. The signal generator here may include a second arbitrary waveform generator or a first digital-to-analog converter. For the convenience of description, hereinafter, the signal generator, the first mixer, the first filter, and the controller will be taken as an example to illustrate the working principle of the trapezoidal wave generation module 20, and details will not be repeated hereinafter. Please refer to Figure 5 , Figure 5 which is a schematic diagram of the working principle of the trapezoidal wave generation module provided by the present application for generating the target trapezoidal wave signal. As Figure 5As shown, the signal generator can generate a first input signal with a frequency of the above-mentioned stepped frequency f2 (e.g., f2 = Δf). Here, the first input signal can be the first input signal shown in Figure 5 as shown in 5a. The first input signal shown in Figure 5 as shown in 5a can be obtained. The signal frequency of the first input signal is Δf. The controller can output a second input signal for generating any stepped wave signal of the target trapezoidal wave signal to the first mixer within a duration T based on the input of the first filter. Among them, the duration T is determined by the order and the second period, that is, T = T2 / N1 = NT / N. The second input signal for generating any stepped wave signal of the target trapezoidal wave signal is the previous stepped wave signal of any stepped wave signal. Here, the second input signal can be the second input signal shown in Figure 5 as shown in 5b. The second input signal shown in Figure 5 as shown in 5b can be obtained. The second input signal output by the controller to the first mixer within the first duration T (e.g., 0 - T) of the second period is 0 (e.g., the second input signal can be made 0 by disconnecting the circuit (such as the circuit between the controller and the first filter)). The second input signal output by the controller to the first mixer within any duration T (e.g., T - 2T) after the 0 - T duration of the second period is the output signal of the first filter within the previous duration T (e.g., the above 0 - T) of any duration T (i.e., the first stepped wave signal). That is, the second input signal for generating the second stepped wave signal of the target trapezoidal wave signal is the first stepped wave signal.

[0061] Furthermore, the first mixer can perform time-domain multiplication on the first input signal input by the signal generator and the second input signal input by the controller and output a first output signal to the first filter. The first output signal here includes a first difference frequency signal and a first sum frequency signal. The first difference frequency signal can be the signal obtained by subtracting the frequencies of the first input signal and the second input signal in the first output signal. The first sum frequency signal can be the signal obtained by adding the frequencies of the first input signal and the second input signal in the first output signal. In this application, the difference frequency signals in the first output signal used to generate any stepped wave signal can be collectively referred to as the first difference frequency signals. In this application, the sum frequency signals in the first output signal used to generate any stepped wave signal can also be collectively referred to as the first difference frequency signals. It can be understood that the first mixer can perform time-domain multiplication on the first input signal shown in Figure 5 as shown in 5a and the second input signal shown in Figure 5 as shown in 5b to obtain the first output signal shown in Figure 5 as shown in 5c. In Figure 5In the first output signal shown in Fig. 5c, the signal represented by a solid line is the first sum frequency signal, and the signal represented by a dashed line is the first difference frequency signal. For example, the first mixer can perform time-domain multiplication on the first input signal with a signal frequency of f1 and the second input signal with a signal frequency of f2 within any duration T (such as T to 2T), so as to obtain the first difference frequency signal within the duration of T to 2T with a signal frequency of 0 and the first sum frequency signal within the duration of T to 2T with a signal frequency of 2Δf (i.e., f1 + f2 = Δf + Δf = 2Δf).

[0062] At this time, the first filter can filter out the first difference frequency signal in the first output signal input by the first mixer, and use the first sum frequency signal in the first output signal as any stepped wave signal with a duration of T, and generate a target trapezoidal wave signal according to each stepped wave signal (such as the trapezoidal wave signals from the 1st to the Nth order). It can be understood that the first filter can be a high-pass filter. Assume that the starting frequency of the passband of the first filter can be represented as f FIL1 , and the relationship between the starting frequency f FIL1 of the passband and time t can be shown as in the following formula (5):

[0063] f FIL1 = nΔf, (5)

[0064] where n can represent the number of the first period T, Δf can represent the maximum frequency of the target sawtooth wave signal, and time t can satisfy the following conditions: nT + kNT < t ≤ (n + 1)T + kNT, n < N. According to the above formula (5), the first filter can obtain the filtered signal of the first filter as shown in Figure 5 Fig. 5d. From Figure 5 the filtered signal of the first filter shown in Fig. 5d, it can be obtained that the filtered signals of the first filter within different durations of the second period (such as 0 to NT). Here, the filtered signal of the first filter is used to filter out the first difference frequency signal in the above first output signal to obtain the first sum frequency signal. For example, taking the second stepped wave signal as an example, the signal frequency of the filtered signal of the first filter within the duration of T to 2T is Δf. Since the signal frequency of the first difference frequency signal is 0 < Δf, the first filter can filter out the first difference frequency signal with a signal frequency of 0 in the first output signal according to the filtered signal with a signal frequency of Δf, so as to obtain the first sum frequency signal with a signal frequency of 2Δf, and use the first sum frequency signal with a signal frequency of 2Δf as the second stepped wave signal.

[0065] Furthermore, the first filter can filter out all the first difference frequency signals in the first output signal shown in Figure 5 Fig. 5c according to the filtered signal of the first filter shown in Figure 5 Fig. 5d, so as to output asFigure 5 The target trapezoidal wave signal shown in 5e with the second period T2 (such as T2 = NT), the stepped frequency f2 (such as f2 = Δf), and the order N1 (such as N1 = N). Since Figure 5 the target trapezoidal wave signal shown in 5e can be obtained. Because the second input signal output by the controller to the first mixer within the first time period T (such as 0 - T) of the second period is 0, that is, there is no second input signal at this time, and only the signal generator inputs the first input signal to the first mixer. Therefore, the first stepped wave signal of the target trapezoidal wave signal (such as the trapezoidal wave signal within the time period 0 - T) is the output signal of the first filter within the time period 0 - T, and the output signal of the first filter within the time period 0 - T is the same as the first input signal within the time period 0 - T, that is, the first stepped wave signal has a signal frequency of f1 = Δf; the other trapezoidal wave signals after the first stepped wave signal of the target trapezoidal wave signal are all generated based on the first input signal and the second input signal. For example, the signal frequency of the second stepped wave signal is 2Δf,..., and the signal frequency of the Nth stepped wave signal is NΔf.

[0066] In some feasible embodiments, such as Figure 2 the frequency addition module 30 shown can include Figure 4 the second mixer and the second filter shown. The second mixer can perform time-domain multiplication on the target sawtooth wave signal and the target trapezoidal wave signal, and output a second output signal. Among them, the second output signal can include a second difference frequency signal and a second sum frequency signal. Here, the second output signal can be used to determine the modulation wave signal later. The second filter can filter out the second difference frequency signal in the second output signal input by the second mixer to obtain the second sum frequency signal, and output the second sum frequency signal as the modulation wave signal. For the convenience of description, the working principle of the frequency addition module 30 will be described below taking the second mixer and the second filter as examples, and will not be elaborated further below. Please refer to Figure 6 , Figure 6 which is a schematic diagram of the working principle of the modulation wave signal generated by the frequency addition module provided in this application. As Figure 6 shown, the sawtooth wave generation module 10 can input the target sawtooth wave signal shown in 6a with the maximum frequency f1 = Δf and the first period T1 = T to the second mixer, and the trapezoidal wave generation module 20 can input the target trapezoidal wave signal shown in 6b with the stepped frequency f2 = Δf, the second period T2 = NT, and the order N1 = N to the second mixer. The second mixer can perform time-domain multiplication on the target sawtooth wave signal shown in Figure 6 6a and the target trapezoidal wave signal shown in Figure 6 6b, and input the second output signal shown in Figure 6 to the second filter. In Figure 6 6c. In Figure 6 6c.Figure 6 In the second output signal shown in FIG. 6c, the signal represented by a solid line is the second sum frequency signal in the second output signal, and the signal represented by a dashed line is the second difference frequency signal in the second output signal. It can be understood that the second filter can be a high-pass filter. Assume that the start frequency of the passband of the second filter can be expressed as f FIL2 , and the relationship between the start frequency f FIL2 of the passband and time t can be as shown in the following formula (6):

[0067] f FIL2 = (n + 1)Δf, (6)

[0068] where n can represent the number of the first periods T, Δf can represent the maximum frequency of the target sawtooth signal, and time t can satisfy the following condition: nT + kNT < t ≤ (n + 1)T + kNT, n < N. According to the above formula (6), the second filter can obtain the filtered signal of the second filter as shown in Figure 6 FIG. 6d. From Figure 6 the filtered signal of the second filter shown in FIG. 6d, the filtered signals of the second filter at different time lengths within the modulation period (such as 0 - NT) can be obtained. Here, the filtered signal of the second filter is used to filter out the second difference frequency signal in the above second output signal to obtain the second sum frequency signal. For example, within the time length from T to 2T, the signal frequency of the filtered signal of the second filter is 2Δf. Since the signal frequency of the second difference frequency signal is less than 2Δf, the second filter can filter out the second difference frequency signal with a signal frequency less than 2Δf in the second output signal according to the filtered signal with a signal frequency of 2Δf, so as to obtain the second sum frequency signal with a signal frequency greater than 2Δf. Further, the second filter can filter out all the second difference frequency signals in the second output signal shown in Figure 6 FIG. 6c according to the filtered signal of the second filter shown in Figure 6 FIG. 6d, so as to output a modulated wave signal with a modulation period NT and a modulation bandwidth NΔf as shown in Figure 6 FIG. 6e.

[0069] In some feasible embodiments, the modulation module shown in Figure 2 may include a modulator (which may also be referred to as an optoelectronic modulator). The second filter can input the modulated wave signal shown in Figure 6 FIG. 6e to the modulator, and the modulator can load the modulated wave signal shown in Figure 6 FIG. 6e onto the light wave shown in Figure 3 FIG. 3d output by the laser, and output a chirped optical wave with a modulation period NT and a modulation bandwidth NΔf as shown in Figure 3 FIG. 3e. It can be understood that based on the above Figure 3It can be obtained that, since the slope of the target sawtooth wave signal generated by the sawtooth wave generation module 10 is the same within each modulation period NT, and the target trapezoidal wave signal generated by the trapezoidal wave generation module 20 is in an upward trend within each modulation period NT, the finally output chirped light is a chirped light with a single slope.

[0070] Optionally, the chirped light can also be a chirped light with at least two slopes (such as two slopes), a triangular chirped light, or a chirped light of other modes, which can be specifically determined according to the actual application scenario and are not limited herein. For the convenience of description, the chirped light with two slopes or the triangular chirped light will be taken as an example for illustration hereinafter, and will not be elaborated further.

[0071] See Figure 7 , Figure 7 which is another schematic diagram of the working principle of the signal modulation device provided by this application.

[0072] As Figure 7 shown, the sawtooth wave generation module 10 can generate the target sawtooth wave signal as shown in Figure 7 7a and input the target sawtooth wave signal to the frequency addition module 30. For the convenience of description, a modulation period (such as 0 to (N + N / 2)T) will be taken as an example for illustration hereinafter, and will not be elaborated further. From the target sawtooth wave signal shown in Figure 7 7a above, it can be obtained that the slope of the target sawtooth wave signal generated within the duration of 0 to NT is slope 1, the maximum frequency is Δf, and the first period is T. The slope of the target sawtooth wave signal generated within the duration of NT to (N + N / 2)T is slope 2 (where slope 2 is different from slope 1), the maximum frequency is Δf, and the first period is T / 2. The trapezoidal wave generation module 20 can generate the target trapezoidal wave signal as shown in Figure 7 7b and input the target trapezoidal wave signal to the frequency addition module 30. From the target trapezoidal wave signal shown in Figure 7 7b, it can be obtained that the signal frequency of the first stepped trapezoidal wave signal of the target trapezoidal wave signal generated within the duration of 0 to NT is Δf, the signal frequency of the second stepped trapezoidal wave signal is 2Δf,..., the signal frequency of the Nth stepped trapezoidal wave signal is NΔf. That is, the signal frequency of the target trapezoidal wave signal generated by the trapezoidal wave generation module 20 within the duration of 0 to NT is in an upward trend, and the stepped frequency of the target trapezoidal wave signal generated within the duration of 0 to NT is Δf, the second period is NT, and the number of steps is N. At the same time, from Figure 7The target trapezoidal wave signal shown in Figure 7b can also be obtained. The signal frequency of the first-step trapezoidal wave signal of the target trapezoidal wave signal generated within the time period of NT to (N+N / 2)T is NΔf,..., the signal frequency of the N-1-step trapezoidal wave signal is 2Δf, and the signal frequency of the N-step trapezoidal wave signal is Δf, that is, the signal frequency of the target trapezoidal wave signal generated by the trapezoidal wave generation module 20 within the time period of NT to (N+N / 2)T shows a downward trend, and the step frequency of the target trapezoidal wave signal generated within the time period of NT to (N+N / 2)T is Δf, the second period is NT / 2 (that is, T / 2×N), and the order is N.

[0073] Furthermore, the frequency addition module 30 generates the sawtooth wave Figure 7 The target sawtooth wave signal shown in FIG7a and the trapezoidal wave generating module 20 are generated as shown in FIG7a. Figure 7 The target trapezoidal wave signal shown in 7b is frequency-added and input to the modulation module 40 as shown in FIG. Figure 7 The modulated wave signal with the above slope 1 and slope 2 shown in 7c is understood to be Figure 7 The modulation wave signal shown in 7c can be obtained. The slope of the signal frequency of the modulation wave signal in the time period of 0 to NT is the above slope 1, and the slope of the signal frequency of the modulation wave signal in the time period of NT to (N+N / 2)T is the above slope 2. At this time, the modulation module 40 can Figure 7 The modulated wave signal with the above slope 1 and slope 2 shown in 7c is loaded on the laser output as shown in FIG. Figure 7 For the light wave with frequency f0 shown in 7d, the output is Figure 7 The linear frequency modulated light with the above slope 1 and slope 2 is shown in 7e. Figure 7 The linear frequency modulated light shown in 7e can be obtained, and the modulation period of the linear frequency modulated light with the above-mentioned slope 1 and slope 2 is (N+N / 2)T, and the modulation bandwidth is NΔf. It can be understood that the generation process of the linear frequency modulated light with slope 1 and slope 2 within the time length of (N+N / 2)T to 3NT can be specifically referred to the generation process of the linear frequency modulated light with slope 1 and slope 2 within the time length of 0 to (N+N / 2)T, and will not be repeated below. It can be seen that the present application can adjust the sawtooth wave generation module 10 and the trapezoidal wave generation module 20 respectively, such as adjusting the maximum frequency and the first period of the sawtooth wave signal and the step frequency and the second period of the trapezoidal wave signal to generate a linear frequency modulated light with two slopes, which can be expanded to a high bandwidth (such as NΔf), with high linearity, strong flexibility and stronger adaptability.

[0074] See also Figure 8 , Figure 8 This is another schematic diagram of the working principle of the signal modulation device provided by this application.

[0075] As shown Figure 8 in FIG. 8a, the sawtooth wave generation module 10 can generate a target sawtooth wave signal as shown Figure 8 in FIG. 8a, and input the target sawtooth wave signal to the frequency addition module 30. From the target sawtooth wave signal shown Figure 8 in FIG. 8a, it can be obtained that the slope of the target sawtooth wave signal generated within the time duration of 0 to NT is slope 1, the maximum frequency is Δf, and the first period is T. The slope of the target sawtooth wave signal generated within the time duration of NT to 2NT is slope 3 (where slope 3 can be the negative of slope 1), the maximum frequency is Δf, and the first period is T. The trapezoidal wave generation module 20 can generate a target trapezoidal wave signal as shown Figure 8 in FIG. 8b, and input the target trapezoidal wave signal to the frequency addition module 30. From the target trapezoidal wave signal shown Figure 8 in FIG. 8b, it can be obtained that the signal frequency of the first stepped trapezoidal wave signal of the target trapezoidal wave signal generated within the time duration of 0 to NT is Δf, the signal frequency of the second stepped trapezoidal wave signal is 2Δf,..., the signal frequency of the Nth stepped trapezoidal wave signal is NΔf. That is, the signal frequency of the target trapezoidal wave signal generated by the trapezoidal wave generation module 20 within the time duration of 0 to NT shows an upward trend, and the stepped frequency of the target trapezoidal wave signal generated within the time duration of 0 to NT is Δf, the second period is NT, and the number of steps is N. At the same time, from the target trapezoidal wave signal shown Figure 8 in FIG. 8b, it can also be obtained that the signal frequency of the first stepped trapezoidal wave signal of the target trapezoidal wave signal generated within the time duration of NT to 2NT is NΔf,..., the signal frequency of the (N - 1)th stepped trapezoidal wave signal is 2Δf, and the signal frequency of the Nth stepped trapezoidal wave signal is Δf. That is, the signal frequency of the target trapezoidal wave signal generated by the trapezoidal wave generation module 20 within the time duration of NT to 2NT shows a downward trend, and the stepped frequency of the target trapezoidal wave signal generated within the time duration of 0 to NT is Δf, the second period is NT, and the number of steps is N.

[0076] Furthermore, the frequency addition module 30 adds the frequencies of the target sawtooth wave signal generated by the sawtooth wave generation module 10 as shown Figure 8 in FIG. 8a, and the target trapezoidal wave signal generated by the trapezoidal wave generation module 20 as shown Figure 8 in FIG. 8b, and inputs a triangular modulation wave signal as shown Figure 8 in FIG. 8c to the modulation module 40. It can be understood that from the triangular modulation wave signal shown Figure 8 in FIG. 8c, it can be obtained that the signal frequency of the modulation wave signal within the time duration of 0 to NT changes linearly in a positive direction, and the signal frequency of the modulation wave signal within the time duration of NT to 2NT changes linearly in a negative direction. At this time, the modulation module 40 can load the triangular modulation wave signal as shown Figure in FIG. 8c onto the laser output as shown ​On the light wave with a frequency of f0 shown in Fig. 8d, output as ​ the triangular chirped light shown in Fig. 8e. From ​ the triangular chirped light shown in Fig. 8e, it can be obtained that the modulation period of the triangular chirped light is 2NT, and the modulation bandwidth is NΔf. Thus, it can be seen that the present application can adjust the sawtooth wave generation module 10 and the trapezoidal wave generation module 20 respectively. For example, the maximum frequency and the first period of the sawtooth wave signal, and the step frequency and the second period of the trapezoidal wave signal can be adjusted to generate the triangular chirped light, which can be extended to a high bandwidth (such as NΔf), with high linearity, strong flexibility, and better adaptability.

[0077] See ​ , ​ which is a schematic structural diagram of the laser light source system provided by the present application. As ​ shown, the laser light source system 1 may include a laser 11 and a signal modulation device 12 (such as the signal modulation device shown in the above ​ or ​ ). The structure and working principle of the signal modulation device here can be referred to the specific implementation manners of the above ​ embodiment, which will not be elaborated hereinafter. In the present application, the chirped light source provided by the laser light source system (such as the above laser light source system 1) can meet the high-bandwidth light source required by lidar, with strong flexibility and better applicability.

[0078] See ​ , ​ which is a schematic flowchart of the signal modulation method provided by the present application. The signal modulation method provided by the present application is applicable to the signal modulation device provided in the above ​ , and this method includes the following steps S101 - step S103:

[0079] Step S101, generate a target sawtooth wave signal.

[0080] In some feasible embodiments, the signal modulation device can collect the modulation bandwidth NΔf of the chirped optical signal, the modulation period NT of the chirped optical signal, and the maximum frequency f1 of the sawtooth signal (such as f1 = Δf) set by the user through the sawtooth wave parameter input interface, and calculate the first period T1 of the sawtooth signal, that is, T1 = NT / (NΔf / f1) = NT / (NΔf / Δf) = NT / N = T. The signal modulation device can collect the modulation bandwidth NΔf, the modulation period NT, and the first period T1 of the sawtooth signal (such as T1 = T) set by the user through the sawtooth wave parameter input interface, and calculate the maximum frequency f1 of the sawtooth signal, that is, f1 = NΔf / (NT / T1) = NΔf / (NT / T) = NΔf / N = Δf. Optionally, the signal modulation device can also directly call the known modulation bandwidth NΔf, the modulation period NT, and the maximum frequency f1 of the sawtooth signal (such as f1 = Δf) from the signal parameter library, and calculate the first period T1 of the sawtooth signal (that is, T1 = T); or the signal modulation device can also directly call the known modulation bandwidth NΔf, the modulation period NT, and the first period T1 of the sawtooth signal (such as T1 = T) from the signal parameter library, and calculate the maximum frequency f1 of the sawtooth signal (that is, f1 = Δf). The signal parameter library here can contain signal parameters stored or configured by the user. Optionally, the sawtooth wave generation module 10 can also directly collect the maximum frequency f1 of the sawtooth signal (such as f1 = Δf) and the first period T1 of the sawtooth signal (such as T1 = T) set by the user through the sawtooth wave parameter input interface. It can be understood that the specific process of collecting or calculating the maximum frequency and the first period of the sawtooth signal here can be determined according to the actual application scenario and will not be limited here.

[0081] Further, after the signal modulation device collects or calculates the first period T1 and the maximum frequency f1 of the sawtooth signal, it can generate a target sawtooth signal based on the first period T1 and the maximum frequency f1 of the sawtooth signal. The target sawtooth signal here can be used to generate a modulation wave signal later, and the maximum frequency of the target sawtooth signal is f1, and f1 = Δf, and the period of the target sawtooth signal is the first period T1, and T1 = T.

[0082] Step S102, generate a target trapezoidal wave signal.

[0083] In some feasible embodiments, the signal modulation device can collect the modulation bandwidth NΔf, modulation period NT, and the maximum frequency f1 of the sawtooth wave signal set by the user through the trapezoidal wave parameter input interface, calculate the second period T2 of the trapezoidal wave signal (i.e., T2 = NT), the step frequency f2 of the trapezoidal wave signal (i.e., f2 = f1 = Δf), and the order N1 of the trapezoidal wave signal, that is, N1 = NΔf / f1 = NΔf / Δf = N. The signal modulation device can collect the modulation bandwidth NΔf, modulation period NT, and the first period T1 of the sawtooth wave signal set by the user through the trapezoidal wave parameter input interface, and calculate the second period T2 of the trapezoidal wave signal (i.e., T2 = NT), the order N1 of the trapezoidal wave signal (i.e., N1 = NT / T1 = NT / T = N), and the step frequency f2 of the trapezoidal wave signal (i.e., f2 = NΔf / N1 = NΔf / N = Δf). Optionally, the signal modulation device can also directly call the known modulation bandwidth NΔf, modulation period NT, and the maximum frequency f1 of the sawtooth wave signal (such as f1 = Δf) from the above signal parameter library, calculate the second period T2 of the trapezoidal wave signal (i.e., T2 = NT), the step frequency f2 of the trapezoidal wave signal (i.e., f2 = f1 = Δf), and the order N1 of the trapezoidal wave signal (i.e., N1 = N); or the signal modulation device can also directly call the known modulation bandwidth NΔf, modulation period NT, and the first period T1 of the sawtooth wave signal (such as T1 = T) from the above signal parameter library, calculate the second period T2 of the trapezoidal wave signal (i.e., T2 = NT), the order N1 of the trapezoidal wave signal (i.e., N1 = N), and the step frequency f2 of the trapezoidal wave signal (i.e., f2 = Δf). Optionally, the trapezoidal wave generation module 20 can also directly collect the second period T2 of the trapezoidal wave signal (i.e., T2 = NT), the order N1 of the trapezoidal wave signal (i.e., N1 = N), and the step frequency f2 of the trapezoidal wave signal (i.e., f2 = Δf) configured by the user through the trapezoidal wave parameter input interface. The specific process of collecting or calculating the order, step frequency, and second period of the trapezoidal wave signal here can be determined according to the actual application scenario and is not limited here.

[0084] In some feasible embodiments, after the signal modulation device determines the order N1 of the trapezoidal wave signal, the step frequency f2, and the second period T2, it can obtain the first input signal and generate a first stepped wave signal with a duration of T based on the first input signal. The frequency of the first input signal is the same as the step frequency f2. Further, the signal modulation device can determine the duration T of a stepped wave signal (i.e., T2 / N1 = NT / N1 = T) based on the order N1 (such as the above-mentioned N) and the second period T2 (such as T2 = NT), and generate any stepped wave signal with a duration of T based on the first input signal and the second input signal for generating any stepped wave signal after the first stepped wave signal. Here, the second input signal for generating any stepped wave signal is the previous stepped wave signal of any stepped wave signal. Specifically, the above-mentioned signal modulation device can obtain the second input signal for generating any stepped wave signal based on the previous stepped wave signal of any stepped wave signal. At this time, the signal modulation device can perform time-domain multiplication on the first input signal and the second input signal for generating any stepped wave signal after the first stepped wave signal within the duration T to obtain the first output signal for generating any stepped wave signal. Among them, the first output signal includes a first difference frequency signal and a first sum frequency signal. The signal modulation device can filter out the first difference frequency signal in the first output signal to obtain the first sum frequency signal in the first output signal, and use the first sum frequency signal in the first output signal as any stepped wave signal with a duration of T. Further, the signal modulation device can generate a target trapezoidal wave signal with an order N1 (i.e., N1 = N) based on each stepped wave signal (such as the 1st to Nth stepped wave signals). The step frequency of the target trapezoidal wave signal here is f2, and f2 = Δf. The period of the target trapezoidal wave signal is the second period T2, and T2 = NT. The order of the target trapezoidal wave signal is N1, and the target trapezoidal wave signal can be used to generate a modulation wave signal subsequently.

[0085] Step S103: Generate a modulation wave signal according to the target sawtooth wave signal and the target trapezoidal wave signal, and load the modulation wave signal onto the light wave output by the laser to obtain chirped light.

[0086] In some feasible embodiments, the above-mentioned signal modulation device can perform time-domain multiplication on the target sawtooth wave signal and the target trapezoidal wave signal to output a second output signal. The second output signal includes a second difference frequency signal and a second sum frequency signal. Further, the signal modulation device can filter out the second difference frequency signal in the second output signal to obtain the second sum frequency signal, and use the second sum frequency signal as the modulation wave signal. At this time, the signal modulation device can load the modulation wave signal onto the light wave output by the laser to obtain high-bandwidth chirped light with high linearity, strong flexibility, and strong applicability.

[0087] Optionally, the chirped light can be chirped light with at least one slope, chirped light with at least two slopes (such as two slopes), triangular chirped light, or chirped light of other modes, which can be specifically determined according to the actual application scenario and are not limited herein.

[0088] In specific implementation, for more operations performed by the signal modulation device in the signal modulation method provided by this application, reference can be made to ​ the implementation manner performed by the signal modulation device in the signal modulation device and its working principle shown, which will not be elaborated herein.

[0089] In this application, the signal modulation device can achieve cyclic frequency shift on the electrical signal through the trapezoidal wave generation module to expand to a high bandwidth, thereby obtaining high-bandwidth chirped light that meets the requirements, with lower cost. At the same time, the parameters of the sawtooth wave generation module and the trapezoidal wave generation module can be adjusted respectively to obtain different modes of chirped light, with high linearity, strong flexibility, and strong applicability.

[0090] As described above, the above are only specific implementation manners of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the above-mentioned claims.

Claims

1. A signal modulation device, characterized in that, The signal modulation device includes a sawtooth wave generation module, a trapezoidal wave generation module, a frequency addition module, and a modulation module; The sawtooth wave generation module is used to generate a target sawtooth wave signal; The trapezoidal wave generation module is used to generate a target trapezoidal wave signal, where the maximum frequency of the target sawtooth wave signal is the same as the step frequency of the target trapezoidal wave signal, and the ratio of the second period of the target trapezoidal wave signal to the first period of the target sawtooth wave signal is the same as the order of the target trapezoidal wave signal; The frequency addition module is used to generate a modulation wave signal based on the target sawtooth wave signal generated by the sawtooth wave generation module and the target trapezoidal wave signal generated by the trapezoidal wave generation module, where the minimum signal frequency of the modulation wave signal is the same as the step frequency of the target trapezoidal wave signal; The modulation module is used to load the modulation wave signal generated by the frequency addition module onto the light wave output by the laser to output a chirped light, where the minimum signal frequency of the chirped light is the sum of the frequency of the light wave and the minimum signal frequency of the modulation wave signal.

2. The signal modulation device according to claim 1, characterized in that, The bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period; The first period of the target sawtooth wave signal is determined by the maximum frequency of the target sawtooth wave signal, the modulation bandwidth, and the modulation period.

3. The signal modulation device according to claim 1, wherein The bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period; The maximum frequency of the target sawtooth wave signal is determined by the first period of the target sawtooth wave signal, the modulation bandwidth, and the modulation period.

4. The signal modulation device according to claim 1, characterized in that, The bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period; The second period of the target trapezoidal wave signal is determined by the modulation period, the step frequency of the target trapezoidal wave signal is determined by the maximum frequency of the target sawtooth wave signal, and the order of the target trapezoidal wave signal is determined by the modulation bandwidth and the maximum frequency of the target sawtooth wave signal.

5. The signal modulation device according to claim 1, wherein The bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period; The second period of the target trapezoidal wave signal is determined by the modulation period, the order of the target trapezoidal wave signal is determined by the modulation period and the first period of the target sawtooth wave signal, and the step frequency of the target trapezoidal wave signal is determined by the modulation bandwidth and the order.

6. The signal modulation device according to claim 1, wherein The trapezoidal wave generation module includes a signal generator, a controller, a first mixer, and a first filter; The signal generator is used to generate a first input signal, and the frequency of the first input signal is the same as the step frequency; The controller is used to output, within a duration T, a second input signal for generating any stepped wave signal of the target trapezoidal wave signal to the first mixer based on the input of the first filter, where the second input signal for generating any stepped wave signal of the target trapezoidal wave signal is the previous stepped wave signal of the any stepped wave signal, and the duration T is determined by the order and the second period; The first mixer is configured to perform time-domain multiplication on a first input signal input by the signal generator and a second input signal input by the controller, and output a first output signal to the first filter. The first output signal includes a first difference frequency signal and a first sum frequency signal. The first filter is configured to filter out the first difference frequency signal in the first output signal input by the first mixer, and use the first sum frequency signal in the first output signal as any stepped wave signal with a duration of T.

7. The signal modulation device according to claim 6, wherein The second input signal output by the controller to the first mixer within the first duration T of the second period is 0. The second input signal output by the controller to the first mixer within any duration T after the first duration T of the second period is the output signal of the first filter within the previous duration T of the any duration T.

8. The signal modulation device according to claim 7, wherein The first stepped wave signal of the target trapezoidal wave signal is the output signal of the first filter within the first duration T of the second period.

9. The signal modulation device according to any one of claims 1-8, characterized in that, The frequency addition module includes a second mixer and a second filter. The second mixer is configured to perform time-domain multiplication on the target sawtooth wave signal and the target trapezoidal wave signal, and output a second output signal, where the second output signal includes a second difference frequency signal and a second sum frequency signal. The second filter is configured to filter out the second difference frequency signal in the second output signal input by the second mixer to obtain the second sum frequency signal, and output the second sum frequency signal as the modulation wave signal.

10. The signal modulation device according to claim 9, characterized in that, The chirped light is any one of a chirped light with one slope, a chirped light with at least two slopes, or a triangular chirped light.

11. A signal modulation method, characterized in that, The method includes: Generating a target sawtooth wave signal. Generating a target trapezoidal wave signal, where the maximum frequency of the target sawtooth wave signal is the same as the stepped frequency of the target trapezoidal wave signal, and the ratio of the second period of the target trapezoidal wave signal to the first period of the target sawtooth wave signal is the same as the order of the target trapezoidal wave signal. Generating a modulation wave signal according to the target sawtooth wave signal and the target trapezoidal wave signal, and loading the modulation wave signal onto the light wave output by the laser to obtain chirped light. Wherein, the minimum signal frequency of the modulation wave signal is the same as the stepped frequency of the target trapezoidal wave signal, and the minimum signal frequency of the chirped light is the sum of the frequency of the light wave and the minimum signal frequency of the modulation wave signal.

12. The signal modulation method according to claim 11, wherein, The bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period; the first period of the target sawtooth wave signal is determined by the maximum frequency of the target sawtooth wave signal, the modulation bandwidth, and the modulation period.

13. The signal modulation method according to claim 11, characterized in that, The bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period; the maximum frequency of the target sawtooth wave signal is determined by the first period of the target sawtooth wave signal, the modulation bandwidth, and the modulation period.

14. The signal modulation method according to claim 11, wherein The bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period; the second period of the target trapezoidal wave signal is determined by the modulation period, the step frequency of the target trapezoidal wave signal is determined by the maximum frequency of the target sawtooth wave signal, and the order of the target trapezoidal wave signal is determined by the modulation bandwidth and the maximum frequency of the target sawtooth wave signal.

15. The signal modulation method according to claim 11, wherein The bandwidth of the chirped light is the modulation bandwidth, and the period of the chirped light is the modulation period; the second period of the target trapezoidal wave signal is determined by the modulation period, the order of the target trapezoidal wave signal is determined by the modulation period and the first period of the target sawtooth wave signal, and the step frequency of the target trapezoidal wave signal is determined by the modulation bandwidth and the order.

16. The signal modulation method according to claim 11, wherein The generating of the target trapezoidal wave signal includes: Obtaining a first input signal, and generating a first stepped wave signal with a duration of T based on the first input signal, where the frequency of the first input signal is the same as the step frequency; Generating the any stepped wave signal with a duration of T based on the first input signal and a second input signal for generating any stepped wave signal after the first stepped wave signal, where the second input signal for generating any stepped wave signal is the previous stepped wave signal of the any stepped wave signal, and the duration T is determined by the order and the second period; Generating a target trapezoidal wave signal with the order based on each stepped wave signal.

17. The signal modulation method according to claim 16, wherein The generating of the any stepped wave signal with a duration of T based on the first input signal and a second input signal for generating any stepped wave signal after the first stepped wave signal includes: Obtaining the second input signal for generating the any stepped wave signal based on the previous stepped wave signal of the any stepped wave signal; Performing time-domain multiplication on the first input signal and the second input signal for generating any stepped wave signal after the first stepped wave signal within the duration T to obtain a first output signal for generating the any stepped wave signal, where the first output signal includes a first difference frequency signal and a first sum frequency signal; Filtering out the first difference frequency signal in the first output signal to obtain the first sum frequency signal in the first output signal, and using the first sum frequency signal in the first output signal as the any stepped wave signal with a duration of T.

18. The signal modulation method according to any one of claims 11-17, characterized in that, The generating of the modulation wave signal according to the target sawtooth wave signal and the target trapezoidal wave signal includes: Performing time-domain multiplication on the target sawtooth wave signal and the target trapezoidal wave signal to output a second output signal, where the second output signal includes a second difference frequency signal and a second sum frequency signal; Filtering out the second difference frequency signal in the second output signal to obtain the second sum frequency signal, and using the second sum frequency signal as the modulation wave signal.

19. A laser light source system, characterized in that, The laser light source system includes a laser and the signal modulation device according to any one of claims 1-10.

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