Laser device, and related device and method

Abstract

Disclosed in the embodiments of the present application are a laser device, and a related device and method. The laser device comprises a laser generation module, a first coupler and a reflection-type space structure composed of at least one reflection element, wherein multiple lasers generated by the laser generation module interfere in the first coupler to form optical pulses, and the optical pulses are divided into two paths, a first optical pulse being transmitted to the reflection element, and a second optical pulse being output; and the first optical pulse is reflected by the reflection element back to the laser generation module. By controlling the movement of a reflection element, the optical path length of an optical pulse transmitted in a space can be changed, so that the repetition frequency of the optical pulse generated by a laser generation module can be adjusted. It should be understood that controlling the movement of the reflection element can adjust the round-trip optical path length of the optical pulse in the space, which is equivalent to multiplying the optical path length of the optical pulse in the space, thereby facilitating a wider range of adjustment of the repetition frequency of the optical pulse. For example, a wide-range frequency modulation exceeding 2 MHz can be realized.

Description

A laser, related equipment and methods

[0001] This application claims priority to Chinese Patent Application No. 202311709242.3, filed on December 12, 2023, entitled "A Laser and Related Devices and Methods", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of lasers, and more particularly to a laser and related devices and methods. Background Technology

[0003] Femtosecond lasers are lasers with time-domain pulse widths on the order of femtoseconds. Femtosecond lasers are not monochromatic; rather, they are composed of light with continuously varying wavelengths around a central wavelength. By utilizing the spatial coherence of these continuous wavelengths within this range, significant temporal compression is achieved, thus enabling femtosecond-level pulse output. Femtosecond-level short-pulse lasers are typically produced using mode-locking techniques.

[0004] Mode-locked fiber lasers output periodic femtosecond pulse trains, with the pulse interval equal to the time period required for the laser to complete one revolution within the resonant cavity. Therefore, the period of the femtosecond laser pulse train is proportional to the cavity length. In the frequency domain, the output of a mode-locked laser is a series of equally spaced comb teeth, hence also called an optical frequency comb. The distance between two comb teeth is the repetition frequency of the laser. In other words, the repetition frequency of a femtosecond laser pulse train is the reciprocal of its period. Therefore, to obtain a repetition frequency-locked femtosecond laser pulse train, feedback control of the cavity length of the laser resonant cavity is required. However, while achieving repetition frequency locking, current technology does not provide a solution for dynamically adjusting the repetition frequency over a wide range and with high precision.

[0005] Summary of the Invention

[0006] This application provides a laser, related devices, and methods that facilitate a wider range of adjustment of the repetition frequency of optical pulses and improve the adjustment accuracy of the repetition frequency.

[0007] In a first aspect, embodiments of this application provide a laser. The laser includes a laser emitting device and a control device. The laser emitting device includes a laser generating module, a first coupler, and a first reflecting element. The laser generating module generates a first laser and a second laser. The first coupler interferes with the first and second lasers to obtain optical pulses, each optical pulse including a first optical pulse transmitted to the first reflecting element and a second optical pulse output. The first reflecting element reflects the first optical pulse back to the laser generating module. The control device adjusts the optical path of the first optical pulse by controlling the movement of the first reflecting element, thereby adjusting the repetition frequency of the optical pulse.

[0008] In this embodiment, the optical path length of the light pulse in space can be changed by controlling the movement of the reflective element, thereby adjusting the repetition frequency of the light pulse generated by the laser generation module. Controlling the movement of the reflective element can adjust the optical path length of the light pulse traveling back and forth in space, which is equivalent to changing the optical path length of the light pulse in space by a factor of two. This is beneficial for adjusting the repetition frequency of the light pulse over a wider range. For example, a wide range of optical path length changes exceeding 60 mm can be achieved, and a wide range of frequency modulation exceeding 2 MHz can be achieved.

[0009] In some possible implementations, the laser generation module includes a nonlinear amplifying loop mirror (NALM) and a pump source, the NALM being connected to a first coupler. The pump source outputs pump light to the NALM, and the NALM generates a first laser and a second laser based on the pump light. For example, the first laser generated by the NALM propagates clockwise within the NALM, and the second laser generated by the NALM propagates clockwise within the NALM. The first and second lasers undergo nonlinear interference through the first coupler to obtain optical pulses, and the optical pulses after passing through the first coupler are split into two paths: a first optical pulse propagating to the first reflecting element and a second optical pulse output. It should be understood that using a NALM reduces the mode-locking threshold and improves the mode-locking resistance to changes in spatial length, ensuring continuous generation of optical pulses even with large-scale adjustment of the optical path length.

[0010] In some possible implementations, the NALM includes a wavelength division multiplexer (WDM) and a gain fiber. The WDM is used to couple the pump light output from the pump source to the gain fiber, which amplifies the light and helps generate stable optical pulses.

[0011] In some possible implementations, NALM also includes a saturable absorber, which enhances the scalability of the solution.

[0012] In some possible implementations, the laser emitting device further includes a second reflective element. The first reflective element reflects the first light pulse to the second reflective element, and then reflects the first light pulse back to the laser generating module. The control device is also used to adjust the optical path of the first light pulse by controlling the movement of the second reflective element. In this implementation, by arranging multiple reflective elements in space, the optical path of the light pulse in space can be adjusted over a wider range, which is more conducive to improving the adjustment range of the repetition frequency of the light pulse.

[0013] In some possible implementations, the laser emitting device further includes an optical fiber collimator for collimating a first optical pulse from a first coupler, wherein the collimated first optical pulse is transmitted in space to a first reflecting element. It should be understood that using an optical fiber collimator to obtain collimated spatial light results in less beam spread, and the reflected optical pulse is more readily coupled into the optical fiber, thus improving the mode-locking effect of the laser.

[0014] In some possible implementations, the beam output by the fiber optic collimator first contracts and then diverges. The collimation distance of the fiber optic collimator is the distance between the collimator and the spatial location where the spot size is the same as the initial spot size; this distance can also be called the working distance of the fiber optic collimator. Since the collimation distance of the fiber optic collimator is greater than the one-way distance of the first optical pulse in space, the spot size reflected back to the fiber optic collimator changes less compared to the initial spot size and has less diffusion, which is more conducive to coupling into the fiber and improves the mode-locking effect of the laser.

[0015] In some possible implementations, the laser emitting device further includes a lens or diffractive optical element (DOE) located between the fiber collimator and the first reflecting element. The lens or DOE is used to shape the first optical pulse from the fiber collimator and transmit the shaped pulse to the first reflecting element. The lens and DOE assist in collimation by shaping the first optical pulse collimated by the fiber collimator. The spot size of the first optical pulse transmitted to the first reflecting element after passing through the lens or DOE is the same as or similar to the initial spot size output by the fiber collimator. This results in a smaller change in the spot size and less diffusion of the first optical pulse reflected back to the fiber collimator compared to the initial spot size, which is more conducive to coupling into the fiber and improving the mode-locking effect of the laser.

[0016] In some possible implementations, the second optical pulse is transmitted to a control device, and the laser emitting device also includes a piezoelectric ceramic transducer (PZT). The PZT is connected to an optical fiber collimator, and the control device is also used to adjust the loading voltage of the PZT according to the second optical pulse to control the movement of the optical fiber collimator, thereby adjusting the optical path of the first optical pulse and thus enabling rapid locking of the repetition frequency of the optical pulse.

[0017] In some possible implementations, the second optical pulse is transmitted to the control device. The laser emitting device also includes a PZT, which is connected to an optical fiber in the laser generating module or an optical fiber used to transmit the first optical pulse. The control device is also used to adjust the loading voltage of the PZT according to the second optical pulse to control the stretching of the optical fiber, so as to adjust the optical path of the optical pulse, thereby enabling rapid locking of the repetition frequency of the optical pulse.

[0018] In some possible implementations, the control device is specifically used to control the movement of the first reflective element according to the loading voltage of the PZT to adjust the optical path of the first optical pulse, thereby adjusting the repetition frequency of the optical pulse. That is, the control device uses a serial control method for the PZT and the first reflective element. First, the optical path of the optical pulse is adjusted by controlling the PZT to achieve frequency locking. If a risk of frequency loss of lock is detected based on the adjustment state of the PZT, the optical path of the optical pulse can be compensated by controlling the movement of the first reflective element to avoid frequency loss of lock during frequency modulation.

[0019] In some possible implementations, the control device includes: a reference signal source, a photodetector, a mixer, a first control module, and a second control module. The reference signal source outputs a target reference signal. The photodetector converts a second optical pulse into an electrical signal. The mixer mixes the target reference signal and the electrical signal to obtain a mixed signal. The first control module adjusts the loading voltage of the PZT according to the mixed signal to control the movement of the fiber collimator, thereby adjusting the optical path of the first optical pulse to lock the repetition frequency of the optical pulse generated by the laser generation module to the frequency of the target reference signal. If the loading voltage of the PZT exceeds a preset voltage range, the second control module controls the movement of the first reflective element according to the loading voltage of the PZT and the preset voltage range to adjust the optical path of the first optical pulse, thereby adjusting the repetition frequency of the optical pulse generated by the laser generation module. This implementation provides a specific way to adjust the repetition frequency of an optical pulse using a control device, achieving frequency locking while also allowing for finer adjustment of the optical pulse's repetition frequency, improving the adjustment accuracy of the repetition frequency and reducing the risk of frequency loss of lock. It should be understood that in some possible scenarios, the first control module and the second control module can be two separate circuit boards, or in other possible scenarios, the first control module and the second control module can be integrated together and implemented through a single controller.

[0020] In some possible implementations, the control device further includes a filter. The filter is used to filter the electrical signal. The mixer is used to mix the target reference signal and the filtered electrical signal to obtain a mixed signal. Filtering can make the frequency error obtained after mixing more accurate.

[0021] In some possible implementations, the frequency modulation step of the reference signal source from outputting the initial reference signal to outputting the target reference signal is less than a first preset value. The first preset value is the frequency adjustment amount of the repetition frequency of the optical pulse corresponding to the maximum adjustment amount of the PZT's loading voltage. In other words, the frequency modulation step of the reference signal source cannot be too large, which can effectively avoid frequency lock-up.

[0022] In some possible implementations, the frequency modulation step of the reference signal source from outputting the initial reference signal to outputting the target reference signal is greater than or equal to a second preset value, where the second preset value is the frequency adjustment amount of the repetition frequency of the optical pulse corresponding to the minimum displacement of the first reflecting element. In other words, the frequency modulation step of the reference signal source cannot be too small, which helps to ensure the speed of the frequency modulation process.

[0023] In some possible implementations, the frequency adjustment amount of the optical pulse repetition frequency corresponding to the minimum displacement of the first reflective element is less than the frequency adjustment amount of the optical pulse repetition frequency corresponding to the maximum adjustment amount of the PZT's applied voltage. In other words, the adjustment range of controlling the movement of the first reflective element cannot be too large, ensuring that frequency lock-up does not occur during frequency modulation.

[0024] In some possible implementations, the laser emitting device further includes a second coupler. The second coupler is used to split the second optical pulse, wherein one of the split optical pulses is transmitted to the control device, and the other split optical pulse is emitted outward.

[0025] Secondly, embodiments of this application provide an electrical signal phase detector, which includes a phase detector, a photodetector, and a laser as described in any embodiment of the first aspect. The photodetector converts the light output from the laser into a first electrical signal and transmits the first electrical signal to the phase detector. The phase detector determines the phase difference between the first electrical signal and an input second electrical signal.

[0026] Thirdly, embodiments of this application provide an optical frequency comb device, which includes: a laser beat frequency module, an initial frequency locking module, and a laser as described in any embodiment of the first aspect. The laser beat frequency module is used to obtain an initial frequency signal by performing spectral spreading, frequency doubling, and beat frequency detection based on the light pulses emitted by the laser. The initial frequency locking module is used to output a control signal to the laser based on the initial frequency signal. The laser is used to lock the initial frequency according to the control signal and output an optical frequency comb signal.

[0027] Fourthly, embodiments of this application provide an optical module. The optical module includes a laser, an electrical chip, and a modulator as described in any embodiment of the first aspect. The electrical chip is used to drive the modulator to modulate the light emitted by the laser to obtain an optical signal.

[0028] Fifthly, embodiments of this application provide an optical transmission device. This optical transmission device includes a wavelength division multiplexer and multiple optical modules as described in the fourth aspect. The wavelength division multiplexer is used to combine the optical signals output from the multiple optical modules and output the combined optical signal.

[0029] Sixthly, embodiments of this application provide a method for frequency modulation of optical pulses. This method is applied to a laser, which includes a laser emitting device and a control device. The laser emitting device includes a laser generating module, a first coupler, and a first reflecting element. The method for frequency modulation of optical pulses includes: generating a first laser and a second laser through the laser generating module; interfering the first and second lasers through the first coupler to obtain an optical pulse, the optical pulse including a first optical pulse transmitted to the first reflecting element and a second optical pulse output; reflecting the first optical pulse back to the laser generating module through the first reflecting element; and controlling the movement of the first reflecting element through the control device to adjust the optical path of the first optical pulse.

[0030] In some possible implementations, the laser generation module includes a NALM and a pump source, the NALM being connected to a first coupler. Another method includes: outputting pump light to the NALM via the pump source, and generating a first laser and a second laser via the NALM based on the pump light.

[0031] In some possible implementations, the NALM includes a wavelength division multiplexer (WDM) and a gain fiber, and the method also includes coupling pump light output from a pump source to the gain fiber via the WDM.

[0032] In some possible implementations, NALM also includes a saturable absorber.

[0033] In some possible implementations, the laser emitting device further includes a second reflective element, and the method further includes: reflecting a first light pulse to the second reflective element via the first reflective element, and then reflecting the first light pulse reflected by the second reflective element back to the laser generating module. The control device also controls the movement of the second reflective element to adjust the optical path of the first light pulse.

[0034] In some possible implementations, the laser emitting device further includes an optical fiber collimator. The method also includes collimating an optical pulse from a first coupler using the optical fiber collimator, wherein the collimated first optical pulse propagates in space toward a first reflecting element.

[0035] In some possible implementations, the beam output by the fiber optic collimator first contracts and then diverges. The collimation distance of the fiber optic collimator is the distance between the collimator and the spatial location where the spot size is the same as the initial spot size; this distance can also be called the working distance of the fiber optic collimator. Since the collimation distance of the fiber optic collimator is greater than the one-way distance of the first optical pulse in space, the spot size reflected back to the fiber optic collimator changes less compared to the initial spot size and has less diffusion, which is more conducive to coupling into the fiber and improves the mode-locking effect of the laser.

[0036] In some possible implementations, the laser emitting device further includes a lens or DOE located between the fiber collimator and the first reflecting element. The method also includes: beam shaping of the first optical pulse from the fiber collimator using the lens or DOE, and transmitting the beam-shaped first optical pulse to the first reflecting element. The lens and DOE are used to shape the first optical pulse collimated by the fiber collimator, thereby assisting in collimation. The spot size of the first optical pulse transmitted to the first reflecting element after passing through the lens or DOE is the same as or similar to the initial spot size output by the fiber collimator. This results in a smaller change in the spot size and less diffusion of the first optical pulse reflected back to the fiber collimator compared to the initial spot size, which is more conducive to coupling into the fiber and improves the mode-locking effect of the laser.

[0037] In some possible implementations, the second optical pulse is transmitted to a control device, and the laser emitting device further includes a PZT connected to an optical fiber collimator. The method also includes: controlling the movement of the optical fiber collimator by adjusting the loading voltage of the PZT according to the second optical pulse through the control device, thereby adjusting the optical path of the first optical pulse.

[0038] In some possible implementations, the second optical pulse is transmitted to a control device, and the laser emitting device further includes a PZT (photocopier), which is connected to an optical fiber in the laser generating module or an optical fiber used to transmit the first optical pulse. The method further includes controlling the stretching of the optical fiber by adjusting the loading voltage of the PZT according to the second optical pulse through the control device, thereby adjusting the optical path of the optical pulse.

[0039] In some possible implementations, controlling the movement of the first reflective element by means of a control device includes: controlling the movement of the first reflective element by means of a control device according to the loading voltage of PZT.

[0040] In some possible implementations, the control device includes: a reference signal source, a photodetector, a mixer, a first control module, and a second control module. The method further includes: outputting a target reference signal through the reference signal source; converting a second optical pulse into an electrical signal through the photodetector; mixing the target reference signal and the electrical signal through the mixer to obtain a mixed signal; controlling the movement of the fiber optic collimator by adjusting the loading voltage of the PZT according to the mixed signal through the first control module to adjust the optical path of the first optical pulse, thereby locking the repetition frequency of the optical pulse generated by the laser generation module to the frequency of the target reference signal; if the loading voltage of the PZT exceeds a preset voltage range, controlling the movement of the first reflective element by the second control module according to the loading voltage of the PZT and the preset voltage range to adjust the optical path of the first optical pulse, thereby adjusting the repetition frequency of the optical pulse generated by the laser generation module.

[0041] In some possible implementations, the control device further includes a filter. The method also includes: filtering the electrical signal using the filter, and mixing the target reference signal and the filtered electrical signal using a mixer to obtain a mixed signal.

[0042] In some possible implementations, the frequency modulation step of the reference signal source from outputting the initial reference signal to outputting the target reference signal is less than a first preset value, where the first preset value is the frequency modulation amount of the repetition frequency of the optical pulse corresponding to the maximum adjustment amount of the loading voltage of the PZT.

[0043] In some possible implementations, the frequency modulation step of the reference signal source from outputting the initial reference signal to outputting the target reference signal is greater than or equal to a second preset value, where the second preset value is the frequency adjustment amount of the repetition frequency of the optical pulse corresponding to the minimum distance of the displacement of the first reflective element.

[0044] In some possible implementations, the frequency adjustment of the repetition frequency of the optical pulse corresponding to the minimum displacement of the first reflective element is less than the frequency adjustment of the repetition frequency of the optical pulse corresponding to the maximum adjustment of the loading voltage of the PZT.

[0045] In some possible implementations, the laser emitting device further includes a second coupler. The method also includes splitting the second optical pulse through the second coupler, wherein one of the split optical pulses is transmitted to a control device, and the other split optical pulse is emitted outward.

[0046] In this embodiment, the laser includes a laser generating module, a first coupler, and a reflective spatial structure composed of at least one reflective element. Multiple laser beams generated by the laser generating module are interfered with in the first coupler to form optical pulses, which are then split into two paths: a first optical pulse propagates to the reflective element, and a second optical pulse is output. The first optical pulse is reflected back to the laser generating module by the reflective element. By controlling the movement of the reflective element, the optical path length of the optical pulse in space can be changed, thereby adjusting the repetition frequency of the optical pulse generated by the laser generating module. It should be understood that controlling the movement of the reflective element adjusts the optical path length of the optical pulse traveling back and forth in space, effectively doubling the optical path length, which facilitates a wider range of frequency adjustment of the optical pulse repetition frequency; for example, it can achieve a wide range of frequency modulation exceeding 2MHz. Furthermore, by adjusting the loading voltage of the PZT to lock the repetition frequency of the optical pulse generated by the laser generating module, the direction and distance of the reflective element displacement can be further adjusted according to the loading voltage of the PZT. This achieves frequency locking while allowing for more precise adjustment of the optical pulse repetition frequency, improving the adjustment accuracy of the repetition frequency and reducing the risk of frequency loss. Attached Figure Description

[0047] Figure 1 is a schematic diagram of the first structure of the laser in an embodiment of this application;

[0048] Figure 2 is a schematic diagram of a second structure of the laser in an embodiment of this application;

[0049] Figure 3 is a schematic diagram of a third structure of the laser in an embodiment of this application;

[0050] Figure 4 is a schematic diagram of the fourth structure of the laser in the embodiments of this application;

[0051] Figure 5 is a schematic diagram of the fifth structure of the laser in the embodiments of this application;

[0052] Figure 6 is a first schematic diagram of the optical pulse output by the optical fiber collimator in this embodiment of the present application propagating in space;

[0053] Figure 7 is a second schematic diagram of the optical pulse output by the fiber collimator in this embodiment of the application propagating in space;

[0054] Figure 8 is a third schematic diagram of the optical pulse output by the optical fiber collimator in this embodiment of the application propagating in space;

[0055] Figure 9 is a schematic diagram of the sixth structure of the laser in the embodiments of this application;

[0056] Figure 10 is a schematic flowchart of adjusting the repetition frequency of light pulses in an embodiment of this application;

[0057] Figure 11 is a schematic diagram of the seventh structure of the laser in the embodiments of this application;

[0058] Figure 12 is a graph showing the drift measurement results of the repetition frequency of the optical pulse in the embodiments of this application;

[0059] Figure 13 is a schematic diagram comparing the locked and unlocked repetition frequency of the optical pulse in the embodiments of this application;

[0060] Figure 14 is a schematic diagram of an electrical signal phase detection device according to an embodiment of this application;

[0061] Figure 15 shows an optical frequency comb device in an embodiment of this application;

[0062] Figure 16 is a schematic diagram of an embodiment of the optical pulse frequency modulation method in this application. Detailed Implementation

[0063] This application provides a laser and related devices and methods. The laser includes a laser generating module, a first coupler, and a reflective spatial structure composed of at least one reflective element. Multiple laser beams generated by the laser generating module are interfered with in the first coupler to form optical pulses. These optical pulses are divided into two paths: a first optical pulse is transmitted to the reflective element, and a second optical pulse is output. The first optical pulse is reflected back to the laser generating module by the reflective element. Controlling the movement of the reflective element adjusts the optical path of the first optical pulse in space, effectively doubling its path length and allowing for a wider range of adjustment of the repetition frequency. It should be understood that the laser provided in this application can also be called a mode-locked laser or a mode-locked fiber laser. It can generate highly stable femtosecond lasers and has a wide range of repetition frequency adjustment capabilities, and can be applied to fields such as the fabrication of optical frequency combs, high-precision laser ranging, precision micromachining, fiber optic time-frequency transmission, and the fabrication and calibration of high-precision instruments.

[0064] It should be noted that the terms "first," "second," etc., in this application specification, claims, and the accompanying drawings are used to distinguish similar objects, not to limit a specific order or sequence. It should be understood that the above terms can be used interchangeably where appropriate so that the embodiments described in this application can be implemented in a sequence other than that described in this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0065] Figure 1 is a schematic diagram of the first structure of the laser in this embodiment. As shown in Figure 1, the laser includes a laser emitting device and a control device. The control device is used to adjust the laser emitting device according to the light pulses emitted by the laser emitting device to adjust the repetition frequency of the light pulses and to lock the repetition frequency of the light pulses. For ease of explanation, the laser emitting device is divided into two parts: the laser body 10 and the spatial reflection module 20. This division may not exist in actual product implementation. It should be understood that the laser emitting device requires a sealed and vibration-isolated overall encapsulation and active temperature control. This series of steps can reduce the repetition frequency drift to below 10 Hz.

[0066] Specifically, the laser body 10 includes a laser generation module 101, a first coupler 102, a second coupler 103, a piezoelectric ceramic transducer (PZT) 104, and an optical fiber collimator 105. The spatial reflection module 20 includes a first reflective element 201. The laser generation module 101 is used to generate laser light, for example, the generated laser light includes a first laser and a second laser. The first laser and the second laser undergo nonlinear interference through the first coupler 102 to obtain optical pulses, and the optical pulses after passing through the first coupler 102 are split into two paths, namely a first optical pulse transmitted to the optical fiber collimator 105 and a second optical pulse output. The second optical pulse is split into two paths through the second coupler 103. One of the split optical pulses is transmitted to the control device, and the other split optical pulse is emitted outward. It should be understood that the first coupler 102, the second coupler 103, and the optical fiber collimator 105 are respectively connected by optical fibers. The fiber collimator 105 collimates the input first optical pulse. The collimated first optical pulse is transmitted in space to the first reflective element 201, and then reflected back to the fiber collimator 105 by the first reflective element 201 and transmitted back to the laser generation module 101 along the original path.

[0067] Based on the above introduction, the segment from the laser generation module 101 to the first reflecting element 201 and back can be understood as the transmission of the optical pulse in the laser's resonant cavity. The pulse interval is the time period required for the optical pulse to complete one revolution within the resonant cavity, and the repetition frequency of the optical pulse is the reciprocal of the period. Therefore, the repetition frequency of the optical pulse can be adjusted by regulating the optical path length of the optical pulse in the resonant cavity. Specifically, the control device can adjust the loading voltage of PZT 104 according to the current repetition frequency of the second optical pulse and the desired target frequency, and control the movement of the first reflecting element 201 according to the loading voltage of PZT. The specific method of coordinating the adjustment of PZT 104 and the first reflecting element 201 will be described in detail below. As an example, as shown in Figure 1, PZT 104 is connected to the fiber collimator 105. Adjusting the loading voltage of PZT 104 allows PZT to move the fiber collimator 105 by extending and retracting, which can change the optical path length of the first optical pulse in space, thereby adjusting the repetition frequency of the optical pulse. Controlling the movement of the first reflective element 201 can also change the optical path length of the first light pulse in space, and similarly adjust the repetition frequency of the light pulse. It should be understood that this application does not limit the specific method of controlling the movement of the first reflective element 201. For example, the first reflective element 201 can be placed on a displacement stage, and the movement of the displacement stage can be used to move the first reflective element 201. It should be noted that this application does not limit the number of reflective elements in the spatial reflection module 20 or the size of each reflective element. Several implementation methods with multiple reflective elements are described below, which can adjust the optical path length of the light pulse in space over a wider range, thus improving the adjustment range of the light pulse's repetition frequency.

[0068] Figure 2 is a schematic diagram of a second structure of the laser in an embodiment of this application. Unlike the embodiment shown in Figure 1, as shown in Figure 2, the PZT 104 can also be connected to the optical fiber used for transmitting optical pulses in the laser emitting device. For example, the PZT 104 can be connected to the optical fiber in the laser generation module 101. Alternatively, the PZT 104 can be connected to the optical fiber between the first coupler 102 and the optical fiber collimator 105. Adjusting the loading voltage of the PZT 104 by the control device can cause the PZT to deform, thereby stretching the optical fiber, which can change the optical path length of the optical pulse in the optical fiber and also adjust the repetition frequency of the optical pulse.

[0069] Figure 3 is a schematic diagram of a third structure of the laser in this embodiment. Unlike the embodiment shown in Figure 1, as shown in Figure 3, the spatial reflection module 20 further includes a second reflecting element 202. The first reflecting element 201 reflects the first optical pulse from the fiber collimator 105 to the second reflecting element 202, and the second reflecting element 202 then reflects the first optical pulse back to the first reflecting element 201, which in turn reflects the first optical pulse back to the fiber collimator 105. It should be understood that in practical applications, provided that both the first reflecting element 201 and the second reflecting element 202 can receive the first optical pulse, the control device can control the movement of at least one of the first reflecting elements 201 and 202. For example, the second reflecting element 202 can be moved independently. Alternatively, the first reflecting element 201 and the second reflecting element 202 can be moved together.

[0070] Figure 4 is a schematic diagram of a fourth structure of the laser in this embodiment. Unlike the embodiments shown in Figures 1 and 3, as shown in Figure 4, the spatial reflection module 20 further includes a third reflecting element 203. The first optical pulse from the fiber collimator 105 is reflected back to the fiber collimator 105 along its original path after being reflected sequentially by the first reflecting element 201, the second reflecting element 202, and the third reflecting element 203. It should be understood that in practical applications, provided that the first reflecting element 201, the second reflecting element 202, and the third reflecting element 203 can all receive the first optical pulse, the control device can control at least one of the reflecting elements 201, 202, and 203 to move. For example, the third reflecting element 203 can be kept stationary while the first reflecting element 201 and the second reflecting element 202 can be moved together. Alternatively, the first reflecting element 201 can be kept stationary while the second reflecting element 202 and the third reflecting element 203 can be moved together.

[0071] Figure 5 is a schematic diagram of the fifth structure of the laser in this application embodiment. As shown in Figure 5, in one possible implementation, the laser generation module 101 uses a nonlinear amplifying loop mirror (NALM), which reduces the mode-locking threshold and improves the mode-locking resistance to spatial length changes, ensuring continuous generation of optical pulses even with large-scale adjustment of the optical path length. For example, the first laser generated by the NALM propagates clockwise within the NALM, and the second laser generated by the NALM propagates clockwise within the NALM. The first and second lasers undergo nonlinear interference through the first coupler 102 to obtain optical pulses. The laser generation module 101 includes a pump source 101a, a wavelength division multiplexer 101b, and a gain fiber 101c. The wavelength division multiplexer 101b couples the pump light output from the pump source 101a to the gain fiber 101c using wavelength combining, resulting in light with a different wavelength than the light output from the pump source 101a. It should be understood that both the wavelength division multiplexer 101b and the gain fiber 101c can be considered as part of the NALM. This application does not limit the specific component composition of the NALM. For example, the NALM may also include ordinary optical fiber connected to the gain fiber 101c, or it may include a saturable absorber 101d. The gain fiber 101c can be a doped fiber, including erbium-doped fiber, ytterbium-doped fiber, and thulium-doped fiber. In some possible embodiments, the laser generation module 101 may also incorporate a semiconductor saturable absorber mirror (SESAM) for hybrid mode locking.

[0072] Figure 6 is a schematic diagram of the first type of optical pulse propagation in space by the optical fiber collimator in this embodiment of the present application. As shown in Figure 6, the beam output by the optical fiber collimator first contracts and then diverges. The collimation distance of the optical fiber collimator is the distance between the optical fiber collimator and the spatial position where the spot size is the same as the initial spot size. This distance can also be called the working distance of the optical fiber collimator. In one possible implementation, the collimation distance of the optical fiber collimator is greater than the one-way distance of the first optical pulse propagation in space. In this way, the spot size of the first optical pulse reflected back to the optical fiber collimator changes less compared to the initial spot size and the diffusion is less, which is more conducive to coupling into the optical fiber and improving the mode-locking effect of the laser. Taking the structure shown in Figure 1 as an example, the one-way distance of the first optical pulse propagation in space is the distance from the optical fiber collimator 105 to the first reflecting element 201. The collimation distance of the optical fiber collimator is greater than the maximum distance that the first reflecting element 201 can move. That is to say, the first reflecting element 201 will not move to a position beyond the collimation distance of the optical fiber collimator. Taking the structure shown in Figure 2 as an example, the one-way distance of the first optical pulse in space is the distance from the fiber optic collimator 105 to the first reflective element 201, and then to the second reflective element 202. Taking the structure shown in Figure 3 as an example, the one-way distance of the first optical pulse in space is the distance from the fiber optic collimator 105 to the first reflective element 201, then to the second reflective element 202, and then to the third reflective element 203.

[0073] Figure 7 is a second schematic diagram of the propagation of the optical pulse output by the fiber collimator in space according to an embodiment of this application. As shown in Figure 7, a lens 204 is also provided between the fiber collimator 105 and the first reflecting element 201. The lens 204 is used to shape the beam of the first optical pulse collimated by the fiber collimator 105 to assist in collimation. Taking the scenario shown in Figure 1 as an example, the size of the light spot at the position of the first reflecting element 201 after the first optical pulse is transmitted through the lens 204 is the same as or similar to the initial light spot size output by the fiber collimator 105. In this way, the size of the light spot reflected back to the fiber collimator by the first optical pulse changes less and has less diffusion compared to the initial light spot size, which is more conducive to coupling into the optical fiber and improving the mode-locking effect of the laser. For the scenario shown in Figure 2, the lens 204 makes the size of the light spot at the position of the second reflecting element 202 after the first optical pulse is transmitted the same as or similar to the initial light spot size output by the fiber collimator 105. For the scenario shown in Figure 3, the lens 204 makes the size of the light spot at the position of the third reflective element 203 where the first light pulse is transmitted the same as or similar to the initial light spot size output by the fiber collimator 105.

[0074] Figure 8 is a third schematic diagram of the optical pulse output by the fiber optic collimator in this embodiment of the invention propagating in space. As shown in Figure 8, a diffractive optical element (DOE) 205 is also disposed between the fiber optic collimator 105 and the first reflective element 201. The DOE 205 plays a similar role to the lens 204, and will not be described in detail here.

[0075] Figure 9 is a schematic diagram of the sixth structure of the laser in this embodiment. As shown in Figure 9, the control device includes a reference signal source 301, a photodetector 302, a filter 303, a mixer 304, a first control module 305, and a second control module 306. The reference signal source 301 is used to output a target reference signal. The photodetector 302 is used to convert the second optical pulse into an electrical signal. The filter 303 is used to filter the electrical signal. The mixer 304 is used to mix the target reference signal and the filtered electrical signal to obtain a mixed signal. The first control module 305 can determine the relative error between the repetition frequency of the optical pulse generated by the laser emitting device and the target frequency of the target reference signal based on the mixed signal, and adjust the loading voltage of PZT 104 according to the relative error to control the movement of the fiber collimator 105, so as to adjust the optical path of the first optical pulse in space, thereby quickly locking the repetition frequency of the optical pulse to the target frequency of the target reference signal. Optionally, the control device may not include filter 303, and mixer 304 may mix the target reference signal and the electrical signal from photodetector 302 to obtain a mixed signal. In some possible scenarios, the first control module and the second control module may be two separate circuit boards, or in other possible scenarios, the first control module and the second control module may be integrated together and implemented through a single controller.

[0076] It should be noted that the repetition frequency locking of optical pulses can be achieved within the maximum adjustable range of the PZT 104's loading voltage. The maximum adjustable amount of the PZT 104's loading voltage corresponds to the maximum adjustable amount of the optical pulse repetition frequency that can be achieved through the PZT 104. For example, the maximum range of the PZT 104's loading voltage can be 0V to 150V or -50V to 50V. Taking the maximum range of the PZT 104's loading voltage as 0V to 150V as an example, the maximum adjustable amount of the PZT 104's loading voltage is 150V. The difference between the repetition frequency of the optical pulse when the PZT 104's loading voltage is 150V and the repetition frequency when the PZT 104's loading voltage is 0V is the maximum adjustable amount of the optical pulse repetition frequency that can be achieved through the PZT 104.

[0077] It should be understood that if the applied voltage of PZT 104 exceeds its maximum adjustment range for maintaining repetition frequency lock, the repetition frequency of the optical pulse will lose lock during frequency modulation, a condition known as frequency lock-up. To avoid frequency lock-up, a control range, or preset voltage range, can be set for the applied voltage of PZT 104. This control range is within the maximum adjustment range of its applied voltage. For example, if the maximum range of the applied voltage of PZT 104 is 0V to 150V, the control range can be set to 50V to 100V. If the applied voltage of PZT 104 exceeds the control range, the second control module 306 needs to be activated. For example, if the applied voltage of PZT 104 is less than 50V or greater than 100V, it is considered to be outside the control range. The second control module 306 adjusts the optical path of the first optical pulse by controlling the movement of the first reflective element 201 to adjust the repetition frequency of the optical pulse, thereby compensating for the adjustment of the first control module 305 and bringing the applied voltage of PZT 104 back within the control range. In other words, the control device uses a serial control method for the PZT and the first reflective element. First, the optical path of the optical pulse is adjusted by controlling the PZT to achieve frequency locking. If the adjustment state of the PZT indicates a risk of frequency loss, the optical path of the optical pulse can be compensated by controlling the movement of the first reflective element to avoid frequency loss during frequency modulation.

[0078] As an example, the PZT 104 loading voltage adjusted by the first control module 305 according to the mixing signal exceeds the control range, meaning the optical path of the first optical pulse in space may be too long, and there is a risk of frequency lock-up in the repetition frequency of the optical pulse. The second control module 306 controls the first reflective element 201 to move and shorten the optical path of the first optical pulse in space according to the loading voltage of PZT 104, thereby adjusting the repetition frequency of the optical pulse. The mixing signal also changes accordingly, and the PZT 104 loading voltage adjusted by the first control module 305 according to the mixing signal returns to the control range.

[0079] It should be understood that although the first reflective element 201 has a relatively large movable range, enabling a wide range of frequency modulation, the adjustment range of the first reflective element 201 controlled by the second control module 306 cannot be too large to ensure that frequency lock-up does not occur during frequency modulation. In other words, the second control module 306 can adjust the repetition frequency of the optical pulse more precisely than the first control module 305. Therefore, the frequency adjustment amount corresponding to the minimum displacement of the first reflective element 201 is less than the frequency adjustment amount corresponding to the maximum adjustment amount of the loading voltage of the PZT 104. In other words, the accuracy of a single adjustment of the first reflective element 201's displacement is less than the maximum distance the fiber optic collimator 105 can be moved by adjusting the loading voltage of the PZT 104. As an example, the accuracy of a single adjustment of the first reflective element 201's displacement is 20 nm, and the displacement range of the first reflective element 201 is 50 mm.

[0080] It should be noted that, since the repetition frequency of the optical pulse can be locked within the maximum adjustment range of the PZT 104 loading voltage, if the relative error between the repetition frequency of the optical pulse and the target frequency of the target reference signal is large, it is impossible to lock the repetition frequency of the optical pulse to the target frequency in one go by adjusting the PZT 104 loading voltage. Therefore, a frequency modulation step can be set for the reference signal source 301 according to the maximum adjustment range of the PZT 104 loading voltage. By performing multiple frequency modulations on the reference signal source 301, the signal output by the reference signal source 301 can be adjusted to the target reference signal with the target frequency in multiple steps. A specific implementation method is described below.

[0081] Figure 10 is a schematic flowchart of adjusting the repetition frequency of an optical pulse in an embodiment of this application. As shown in Figure 10, the initial frequency f0 and target frequency f1 of the reference signal source 301 are first determined. Then, the number of steps n required for the reference signal source 301 to tune to the target frequency f1 is calculated based on the frequency modulation step Δf of the reference signal source 301, where n = |f1-f0| / Δf. Furthermore, each time the frequency of the reference signal output by the reference signal source 301 is adjusted, the first control module 305 locks the frequency of the optical pulse to the frequency of the current reference signal based on the loading voltage of the PZT 104 adjusted by the mixing signal. If the loading voltage of the PZT 104 exceeds the control range, the second control module 306 controls the first reflective element 201 to move, so that the loading voltage of the PZT 104 returns to the control range, avoiding frequency loss of lock. If the loading voltage of the PZT 104 does not exceed the control range, the second control module 306 is not activated. Thus, repeating the above operation n times constitutes the complete process of adjusting the repetition frequency of the optical pulse.

[0082] It should be understood that the frequency modulation step Δf of the test signal source 301 cannot be too large, otherwise frequency lock-up may occur. Specifically, the frequency modulation step Δf of the test signal source 301 should be less than a first preset value, which is the frequency adjustment amount of the repetition frequency of the optical pulse corresponding to the maximum adjustment amount of the applied voltage of PZT 104. For example, the range of this first preset value can be 1kHz-50kHz. It should also be understood that the frequency modulation step Δf of the test signal source 301 cannot be too small, otherwise the entire frequency modulation process will be too slow. Specifically, the frequency modulation step Δf of the test signal source 301 should be greater than or equal to a second preset value, which is the frequency adjustment amount of the repetition frequency of the optical pulse corresponding to the minimum displacement distance of the first reflecting element 201. For example, the range of this second preset value can be 1Hz-10Hz.

[0083] It should be noted that in some possible scenarios, the control device may not adjust the loading voltage of PZT 104 based on the feedback of the second optical pulse, but instead manually adjust the loading voltage of PZT 104 using the control device. Correspondingly, the control device can also manually control the movement of the first reflective element 201. In other possible scenarios, the control device may independently control the PZT and the first reflective element. For example, it may directly control the movement of the first reflective element based on the mixing signal to change the optical path of the optical pulse, thereby adjusting the repetition frequency of the optical pulse.

[0084] Figure 11 is a schematic diagram of the seventh structure of the laser in this embodiment. Unlike the laser shown in Figure 1, as shown in Figure 11, the laser emitting device also includes a third coupler 106. The function of the third coupler 106 is similar to that of the second coupler 103. For example, the third coupler 106 can be located in the laser generation module 101. The third coupler 106 adopts a one-input, two-output design. When the laser generation module 101 generates a stable optical pulse, the third coupler 106 can also split the optical pulse generated by the laser generation module 101. One of the split beams is transmitted to the first coupler 102, and the other split beam is emitted outwards. Thus, combined with the optical pulse emitted by the second coupler 103, multiple optical pulses can be emitted.

[0085] Figure 12 shows the measurement results of the repetition frequency drift of the optical pulse in the embodiment of this application. As shown in Figure 12, the horizontal axis represents the measurement duration in seconds (s); the vertical axis represents the frequency drift in mHz. It can be seen that the frequency drift measurement result is approximately ±1 mHz, indicating a good frequency locking effect.

[0086] Figure 13 is a schematic diagram comparing the locked and unlocked repetition frequency of the optical pulse in the embodiments of this application. As shown in Figure 13, the horizontal axis represents the duration in seconds (s); the vertical axis represents the frequency stability. It can be seen that the second stability of the locked repetition frequency is 0.3 MHz, indicating that the frequency locking effect is better.

[0087] As described above, the laser includes a laser generating module, a first coupler, and a reflective spatial structure consisting of at least one reflective element. The multiple laser beams generated by the laser generating module are interfered with in the first coupler to form optical pulses. These pulses are split into two paths: a first optical pulse is transmitted to the reflective element, and a second optical pulse is output. The first optical pulse is reflected back to the laser generating module by the reflective element. By controlling the movement of the reflective element, the optical path length of the optical pulse in space can be changed, thereby adjusting the repetition frequency of the optical pulses generated by the laser generating module. It should be understood that controlling the movement of the reflective element adjusts the round-trip optical path length of the optical pulse in space, effectively doubling the optical path length. This allows for a wider range of adjustment of the optical pulse repetition frequency; for example, it enables a wide range of optical path length changes exceeding 60 mm and a wide range of frequency modulation exceeding 2 MHz. Furthermore, by adjusting the loading voltage of PZT to lock the repetition frequency of the light pulse generated by the laser generation module, the direction and distance of the reflective element displacement can be further adjusted according to the loading voltage of PZT. While achieving frequency locking, the repetition frequency of the light pulse can be adjusted more precisely, improving the adjustment accuracy of the repetition frequency and reducing the risk of frequency loss.

[0088] The following section introduces the possible application scenarios of the aforementioned lasers.

[0089] Figure 14 is a schematic diagram of an electrical signal phase detection device according to an embodiment of this application. As shown in Figure 14, the electrical signal phase detection device includes a laser, a photodetector, and a phase detector. The laser can be any of the lasers described in the above embodiments. Specifically, the photodetector converts the light output from the laser into a first electrical signal and transmits the first electrical signal to the phase detector. The phase detector also receives a second electrical signal as input, for example, a clock signal. The phase detector determines the phase difference between the first and second electrical signals and outputs an electrical phase signal indicating the phase detection error. It should be understood that the signal output by the phase detector can be fed back to the device that outputs the second electrical signal as a reference for adjusting the second electrical signal.

[0090] Figure 15 illustrates an optical frequency comb device according to an embodiment of this application. As shown in Figure 15, the optical frequency comb device includes: a laser beat frequency module, an initial frequency locking module, and a laser as described in any of the above embodiments. The laser beat frequency module is used to obtain an initial frequency signal by performing spectral expansion, frequency doubling, and beat frequency detection based on the light pulses emitted by the laser. The initial frequency locking module is used to output a control signal to the laser based on the initial frequency signal. The laser is used to lock the initial frequency according to the control signal and output an optical frequency comb signal.

[0091] The frequency modulation method of optical pulses provided in the embodiments of this application is described below.

[0092] Figure 16 is a schematic diagram of an embodiment of the optical pulse frequency modulation method in this application. It should be noted that this method is based on the laser described above. For a description of the laser, please refer to the relevant descriptions in the above embodiments; they will not be repeated here. In this example, the optical pulse frequency modulation method includes the following steps.

[0093] 11. Generate the first laser and the second laser through the laser generation module.

[0094] Taking the laser generation module using NALM as an example, the first laser is transmitted clockwise in the NALM, and the second laser is transmitted clockwise in the NALM.

[0095] 12. Optical pulses are obtained by interfering the first laser and the second laser through the first coupler.

[0096] In this process, the first laser and the second laser undergo nonlinear interference through the first coupler to obtain optical pulses. The optical pulses passing through the first coupler are split into two paths, namely the first optical pulse transmitted to the first reflective element and the second optical pulse output.

[0097] 13. The first light pulse is reflected back to the laser generation module through the first reflective element.

[0098] Specifically, a first optical pulse from a first coupler is collimated using an optical fiber collimator to obtain a first optical pulse propagating in space. The first optical pulse can then be reflected back to the optical fiber collimator using a first reflecting element. It should be understood that this application does not limit the number of reflecting elements in space; for example, the first optical pulse may undergo multiple reflections by multiple reflecting elements in space.

[0099] 14. Adjust the loading voltage of PZT through the control device.

[0100] Specifically, the control device converts the input second optical pulse into an electrical signal and filters it. Then, it mixes the filtered electrical signal with the target reference signal to obtain a mixed signal. Furthermore, the control device adjusts the loading voltage of the PZT based on the mixed signal to control the movement or stretching of the fiber collimator, thereby adjusting the optical path of the first optical pulse and locking the repetition frequency of the optical pulse to the frequency of the target reference signal.

[0101] 15. The movement of the first reflective element is controlled by a control device.

[0102] Specifically, the control device determines whether the loading voltage of the PZT exceeds the control range. If so, it indicates that there is a risk of frequency lock-up in the repetition frequency of the optical pulse. At this time, the control device controls the movement of the first reflective element to adjust the optical path of the first optical pulse based on the loading voltage of the PZT, thereby adjusting the repetition frequency of the optical pulse and bringing the loading voltage of the PZT back within the control range.

[0103] It should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A laser, characterized in that, Includes: a laser emitting device and a control device, wherein the laser emitting device includes a laser generating module, a first coupler and a first reflecting element; The laser generation module is used to generate a first laser and a second laser; The first coupler is used to interfere the first laser and the second laser to obtain an optical pulse, the optical pulse including a first optical pulse transmitted to the first reflective element and a second optical pulse output; The first reflective element is used to reflect the first light pulse back to the laser generating module; The control device is used to adjust the optical path of the first light pulse by controlling the movement of the first reflective element.

2. The laser according to claim 1, characterized in that, The laser generation module includes a nonlinear gain loop mirror (NALM) and a pump source. The NALM is connected to the first coupler. The pump source is used to output pump light to the NALM. The NALM is used to generate the first laser and the second laser based on the pump light.

3. The laser according to claim 2, characterized in that, The NALM includes a wavelength division multiplexer (WDM) and a gain fiber, wherein the WDM is used to couple the pump light output from the pump source to the gain fiber.

4. The laser according to claim 2 or 3, characterized in that, The NALM also includes a saturable absorber.

5. The laser according to any one of claims 1 to 4, characterized in that, The laser emitting device also includes a second reflective element; The first reflective element is used to reflect the first light pulse to the second reflective element, and then reflect the first light pulse reflected by the second reflective element back to the laser generating module; The control device is also used to adjust the optical path of the first light pulse by controlling the movement of the second reflective element.

6. The laser according to any one of claims 1 to 5, characterized in that, The laser emitting device further includes an optical fiber collimator, which is used to collimate a first optical pulse from the first coupler, wherein the collimated first optical pulse is transmitted in space to the first reflective element.

7. The laser according to claim 6, characterized in that, The collimation distance of the fiber optic collimator is greater than the one-way distance of the first optical pulse in space.

8. The laser according to claim 6 or 7, characterized in that, The laser emitting device further includes a lens or diffractive optical element (DOE), which is located between the fiber collimator and the first reflective element. The lens or DOE is used to shape the first optical pulse from the fiber collimator and transmit the shaped first optical pulse to the first reflective element.

9. The laser according to any one of claims 6 to 8, characterized in that, The second optical pulse is transmitted to the control device. The laser emitting device also includes a piezoelectric ceramic PZT, which is connected to the fiber collimator. The control device is also used to adjust the loading voltage of the PZT according to the second optical pulse to control the movement of the fiber collimator, so as to adjust the optical path of the first optical pulse.

10. The laser according to any one of claims 1 to 9, characterized in that, The second optical pulse is transmitted to the control device. The laser emitting device also includes a piezoelectric ceramic PZT. The PZT is connected to an optical fiber in the laser generating module or an optical fiber used to transmit the first optical pulse. The control device is also used to adjust the loading voltage of the PZT according to the second optical pulse to control the stretching of the optical fiber, so as to adjust the optical path of the optical pulse.

11. The laser according to claim 9 or 10, characterized in that, The control device is specifically used to control the movement of the first reflective element according to the loading voltage of the PZT.

12. The laser according to any one of claims 9 to 11, characterized in that, The control device includes: a reference signal source, a photodetector, a mixer, a first control module, and a second control module; The reference signal source is used to output the target reference signal; The photodetector is used to convert the second optical pulse into an electrical signal; The mixer is used to mix the target reference signal and the electrical signal to obtain a mixed signal; The first control module is used to adjust the optical path of the first optical pulse by adjusting the loading voltage of the PZT according to the mixing signal; If the loading voltage of the PZT exceeds the preset voltage range, the second control module is used to control the movement of the first reflective element to adjust the optical path of the first light pulse according to the loading voltage of the PZT and the preset voltage range.

13. The laser according to claim 12, characterized in that, The control device also includes a filter; The filter is used to filter the electrical signal from the photodetector; The mixer is used to mix the target reference signal and the filtered electrical signal to obtain a mixed signal.

14. The laser according to claim 12 or 13, characterized in that, The frequency modulation step of the reference signal source from outputting the initial reference signal to outputting the target reference signal is less than a first preset value, where the first preset value is the frequency adjustment amount of the repetition frequency of the optical pulse corresponding to the maximum adjustment amount of the loading voltage of the PZT.

15. The laser according to any one of claims 12 to 14, characterized in that, The frequency modulation step of the reference signal source from outputting the initial reference signal to outputting the target reference signal is greater than or equal to a second preset value, where the second preset value is the frequency adjustment amount of the repetition frequency of the optical pulse corresponding to the minimum displacement of the first reflective element.

16. The laser according to any one of claims 9 to 15, characterized in that, The frequency adjustment amount of the repetition frequency of the optical pulse corresponding to the minimum displacement of the first reflective element is less than the frequency adjustment amount of the repetition frequency of the optical pulse corresponding to the maximum adjustment amount of the loading voltage of the PZT.

17. The laser according to any one of claims 1 to 16, characterized in that, The laser emitting device also includes a second coupler; The second coupler is used to split the second optical pulse, wherein one of the split optical pulses is transmitted to the control device, and the other split optical pulse is emitted outward.

18. An electrical signal phase detector, characterized in that, include: Phase detector, photodetector, and laser as described in any one of claims 1 to 17; The photodetector is used to convert the light output by the laser into a first electrical signal and transmit the first electrical signal to the phase detector; The phase detector is used to determine the phase difference between the first electrical signal and the input second electrical signal.

19. An optical frequency comb device, characterized in that, The optical frequency comb device includes a laser beat frequency module, an initial frequency locking module, and a laser as described in any one of claims 1 to 17; The laser beat frequency module is used to obtain an initial frequency signal by performing spectral expansion, frequency doubling, and beat frequency detection based on the light pulses emitted by the laser; The initial frequency locking module is used to output a control signal to the laser according to the initial frequency signal; The laser is used to lock the initial frequency according to the control signal and output an optical frequency comb signal.

20. A method for frequency modulation of an optical pulse, characterized in that, The method is applied to a laser, the laser comprising: a laser emitting device and a control device, the laser emitting device comprising a laser generating module, a first coupler, and a first reflecting element; the method comprising: The laser generation module generates a first laser and a second laser. The first laser and the second laser are interfered by the first coupler to obtain an optical pulse, the optical pulse including a first optical pulse transmitted to the first reflective element and a second optical pulse output; The first light pulse is reflected back to the laser generation module through the first reflective element; The control device controls the movement of the first reflective element to adjust the optical path of the first light pulse.

21. The method according to claim 20, characterized in that, The laser generation module includes a nonlinear gain loop mirror (NALM) and a pump source, and the method includes: outputting pump light to the NALM through the pump source.

22. The method according to claim 21, characterized in that, The NALM includes a wavelength division multiplexer (WDM) and a gain fiber, and the method includes: coupling the pump light output from the pump source to the gain fiber through the WDM.

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