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

Laser and related equipment and method

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on December 12, 2023, with application number 202311709242.3 and application name “A Laser and Related Equipment and Methods”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of lasers, and in particular to a laser and related equipment and methods. Background Art

[0003] Femtosecond lasers are lasers with pulse widths in the femtosecond range. They are not monochromatic, but rather composed of a range of light with continuously varying wavelengths near a central wavelength. This range of wavelengths is spatially coherent, achieving extreme temporal compression and outputting femtosecond pulses. Lasers with short femtosecond pulses are typically produced using mode-locking technology.

[0004] A mode-locked fiber laser can output a periodic train of femtosecond pulses, where the pulse interval is 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 of the laser resonant cavity. In the frequency domain, the output of a mode-locked laser is a series of equally spaced comb teeth, hence the name optical frequency comb. The spacing 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 inverse of the period. Therefore, in order to obtain a femtosecond laser pulse train with locked repetition frequency, feedback control of the cavity length of the laser resonant cavity is required. However, based on achieving repetition frequency locking, the prior art does not provide a solution that can dynamically adjust the repetition frequency over a large range and with high precision.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a laser and related devices and methods, which are conducive to adjusting the repetition frequency of light pulses over a wider range and improving the adjustment accuracy of the repetition frequency.

[0007] In a first aspect, an embodiment of the present application provides a laser. The laser 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 generating module is used to generate a first laser and a second laser. The first coupler is used to interfere with the first laser and the second laser to obtain a light pulse, wherein the light pulse includes a first light pulse transmitted to the first reflecting element and a second light pulse output. The first reflecting 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 reflecting element to adjust the repetition frequency of the light pulse.

[0008] In this embodiment, controlling the movement of the reflective element changes the optical path length of the light pulses traveling through space, thereby adjusting the repetition rate of the light pulses generated by the laser generation module. Controlling the movement of the reflective element adjusts the optical path length of the light pulses traveling through space, effectively multiplying the optical path length of the light pulses. This facilitates adjusting the repetition rate of the light pulses over a wider range, for example, enabling optical path length changes exceeding 60 mm and frequency modulation exceeding 2 MHz.

[0009] In some possible embodiments, the laser generation module includes a nonlinear amplifying loop mirror (NALM) and a pump source, and the NALM is connected to the first coupler. The pump source is used to output 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 is transmitted clockwise in the NALM, and the second laser generated by the NALM is transmitted clockwise in the NALM. The first laser and the second laser undergo nonlinear interference through the first coupler to obtain light pulses, and the light pulses passing through the first coupler are divided into two paths, namely, the first light pulse transmitted to the first reflective element and the second light pulse output. It should be understood that the use of NALM reduces the mode locking threshold and improves the ability of mode locking to resist spatial length changes, so that the light pulses can be continuously generated even if the optical path of the light pulse is adjusted over a large range.

[0010] In some possible implementations, the NALM includes a wavelength division multiplexer (WDM) and a gain fiber. The WDM is used to couple pump light output by a pump source to the gain fiber. The gain fiber has a light amplification effect, which is conducive to generating stable optical pulses.

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

[0012] In some possible embodiments, the laser emitting device further includes a second reflective element. The first reflective element is configured 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 generation module. The control device is further configured to adjust the optical path length of the first light pulse by controlling the movement of the second reflective element. In this embodiment, by providing multiple reflective elements in space, the optical path length of the light pulse in space can be adjusted over a wider range, further facilitating an increase in the adjustment range of the repetition frequency of the light pulse.

[0013] In some possible embodiments, the laser emitting device further includes a fiber collimator for collimating the first light pulse from the first coupler, wherein the collimated first light pulse is transmitted spatially toward the first reflective element. It should be understood that using a fiber collimator to obtain collimated spatial light reduces light spot diffusion, making the reflected light pulse more easily coupled into the optical fiber, thereby improving the mode locking effect of the laser.

[0014] In some possible implementations, the light beam output by the fiber collimator will first contract and then diverge. The collimation distance of the fiber collimator is the distance between the spatial location and the fiber collimator when the spot size at that spatial location is the same as the initial spot size. This distance can also be referred to as the working distance of the fiber collimator. The collimation distance of the fiber collimator is greater than the one-way distance of the first light pulse in space. As a result, the spot size of the first light pulse reflected back from the fiber collimator changes less than the initial spot size and has less diffusion, making it more conducive to coupling into the optical fiber and improving the mode locking effect of the laser.

[0015] In some possible embodiments, the laser emitting device further includes a lens or a diffractive optical element (DOE), and the lens or DOE is located between the fiber collimator and the first reflecting element. The lens or DOE is used to perform beam shaping on the first light pulse from the fiber collimator, and transmit the beam-shaped first light pulse to the first reflecting element. The lens and DOE are used to perform beam shaping on the first light pulse collimated by the fiber collimator to assist in collimation. The spot size of the first light pulse transmitted to the position of the first reflecting element through the lens or DOE is the same as or similar to the initial spot size output by the fiber collimator. In this way, the spot size of the first light pulse reflected back to the fiber collimator changes less and diffuses less than the initial spot size, which is more conducive to coupling into the optical fiber and is beneficial to improving the mode locking effect of the laser.

[0016] In some possible embodiments, the second light pulse is transmitted to a control device, and the laser emitting device further includes a piezoelectric ceramic transducer (PZT). The PZT is connected to a fiber collimator, and the control device is further configured to adjust a voltage applied to the PZT based on the second light pulse to control movement of the fiber collimator, thereby adjusting the optical path of the first light pulse, thereby rapidly achieving repetition frequency locking of the light pulses.

[0017] In some possible embodiments, the second light pulse is transmitted to the control device, the laser emitting device also includes a PZT, the PZT is connected to the optical fiber in the laser generation module or the optical fiber used to transmit the first light pulse, and the control device is further used to adjust the loading voltage of the PZT according to the second light pulse to control the stretching of the optical fiber to adjust the optical path of the light pulse, thereby quickly achieving repetition frequency locking of the light pulse.

[0018] In some possible embodiments, the control device is specifically configured to control the movement of the first reflective element based on the applied voltage of the PZT to adjust the optical path length of the first light pulse, thereby adjusting the repetition frequency of the light pulse. Specifically, the control device employs serial control of the PZT and the first reflective element, first controlling the PZT to adjust the optical path length of the light pulse to achieve frequency lock. If a risk of frequency loss is detected based on the PZT's adjustment state, the control device can further control the movement of the first reflective element to compensate for the optical path length of the light pulse, thereby preventing frequency loss during the frequency modulation process.

[0019] In some possible embodiments, 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 configured to output a target reference signal. The photodetector is configured to convert a second optical pulse into an electrical signal. The mixer is configured to mix the target reference signal with the electrical signal to generate a mixed signal. The first control module is configured to adjust the applied voltage of the PZT based on the mixed signal to control the movement of the fiber collimator to adjust the optical path length of the first optical pulse, thereby locking the repetition frequency of the optical pulses generated by the laser generation module to the frequency of the target reference signal. If the applied voltage of the PZT exceeds a preset voltage range, the second control module is configured to control the movement of the first reflective element to adjust the optical path length of the first optical pulse based on the applied voltage of the PZT and the preset voltage range, thereby adjusting the repetition frequency of the optical pulses generated by the laser generation module. This embodiment provides a specific implementation method for adjusting the repetition frequency of optical pulses using a control device. While achieving frequency locking, it also allows for more precise adjustment of the repetition frequency of the optical pulses, thereby improving the accuracy of repetition frequency adjustment and reducing the risk of frequency loss. It should be understood that in some possible scenarios, the first control module and the second control module may be two independent circuit boards respectively, or, in other possible scenarios, the first control module and the second control module may also be integrated together and implemented through one controller.

[0020] In some possible implementations, the control device further includes a filter. The filter is configured to filter the electrical signal. The mixer is configured to mix the target reference signal and the filtered electrical signal to produce a mixed signal. The 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, where the first preset value is the frequency adjustment amount of the optical pulse repetition frequency corresponding to the maximum adjustment amount of the PZT applied voltage. In other words, the frequency modulation step of the reference signal source should not be too large to effectively avoid frequency lock.

[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 a frequency adjustment amount for the repetition frequency of the optical pulse corresponding to the minimum displacement distance of the first reflective element. In other words, the frequency modulation step of the reference signal source should not be too small 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 distance of the first reflective element is smaller than the frequency adjustment amount of the optical pulse repetition frequency corresponding to the maximum adjustment amount of the PZT applied voltage. In other words, the adjustment amplitude of controlling the movement of the first reflective element should not be too large to ensure that the frequency does not lose lock during the frequency modulation process.

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

[0025] In a second aspect, embodiments of the present application provide an electrical signal phase detection device, comprising: a phase detector, a photodetector, and a laser as described in any embodiment of the first aspect. The photodetector is configured to convert light output by the laser into a first electrical signal and transmit the first electrical signal to the phase detector. The phase detector is configured to determine a phase difference between the first electrical signal and an input second electrical signal.

[0026] In a third aspect, embodiments of the present application provide an optical frequency comb device, comprising: 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 configured to perform spectrum expansion, frequency multiplication, and beat frequency detection on the optical pulses emitted by the laser to obtain an initial frequency signal. The initial frequency locking module is configured to output a control signal to the laser based on the initial frequency signal. The laser is configured to lock the initial frequency based on the control signal and output an optical frequency comb signal.

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

[0028] In a fifth aspect, an embodiment of the present application provides an optical transmission device. The 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 by the multiple optical modules and output the combined optical signal.

[0029] In a sixth aspect, an embodiment of the present application provides a method for frequency modulation of a light pulse, which is applied to a laser, wherein the laser 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 method for frequency modulation of a light pulse includes: generating a first laser and a second laser by a laser generating module. Interfering the first laser and the second laser by a first coupler to obtain a light pulse, wherein the light pulse includes a first light pulse transmitted to the first reflecting element and a second light pulse output. The first light pulse is reflected back to the laser generating module by the first reflecting element. The movement of the first reflecting element is controlled by the control device to adjust the optical path of the first light pulse.

[0030] In some possible implementations, the laser generation module includes a NALM and a pump source, and the NALM is connected to the first coupler. The method further includes: outputting pump light to the NALM through the pump source, and generating the first laser and the second laser through the NALM according to the pump light.

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

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

[0033] In some possible embodiments, the laser emitting device further includes a second reflective element, and the method further includes: reflecting the 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 further controls the movement of the second reflective element to adjust the optical path length of the first light pulse.

[0034] In some possible implementations, the laser emitting device further includes a fiber collimator. The method further includes: collimating the light pulse from the first coupler using the fiber collimator, wherein the collimated first light pulse is transmitted toward the first reflective element in space.

[0035] In some possible implementations, the light beam output by the fiber collimator will first contract and then diverge. The collimation distance of the fiber collimator is the distance between the spatial location and the fiber collimator when the spot size at that spatial location is the same as the initial spot size. This distance can also be referred to as the working distance of the fiber collimator. The collimation distance of the fiber collimator is greater than the one-way distance of the first light pulse in space. As a result, the spot size of the first light pulse reflected back from the fiber collimator changes less than the initial spot size and has less diffusion, making it more conducive to coupling into the optical fiber and improving the mode locking effect of the laser.

[0036] In some possible embodiments, the laser emitting device further includes a lens or DOE, and the lens or DOE is located between the fiber collimator and the first reflecting element. The method further includes: performing beam shaping on the first light pulse from the fiber collimator through the lens or DOE, and transmitting the beam-shaped first light pulse to the first reflecting element. The lens and DOE are used to perform beam shaping on the first light pulse collimated by the fiber collimator to assist in collimation. The spot size of the first light pulse transmitted to the position of the first reflecting element through the lens or DOE is the same as or similar to the initial spot size output by the fiber collimator. In this way, the spot size of the first light pulse reflected back to the fiber collimator changes less and diffuses less than the initial spot size, which is more conducive to coupling into the optical fiber and is beneficial to improving the mode locking effect of the laser.

[0037] In some possible implementations, the second light pulse is transmitted to a control device, the laser emitting device further includes a PZT, and the PZT is connected to a fiber collimator. The method further includes: controlling the movement of the fiber collimator by adjusting a voltage applied to the PZT by the control device in response to the second light pulse to adjust the optical path length of the first light pulse.

[0038] In some possible implementations, the second light pulse is transmitted to a control device, and the laser emitting device further includes a PZT connected to an optical fiber in the laser generation module or an optical fiber used to transmit the first light pulse. The method further includes: controlling the stretching of the optical fiber by adjusting a voltage applied to the PZT by the control device based on the second light pulse to adjust the optical path length of the light pulse.

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

[0040] In some possible embodiments, 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 via the reference signal source; converting a second optical pulse into an electrical signal via the photodetector; mixing the target reference signal and the electrical signal via the mixer to obtain a mixed signal; adjusting the applied voltage of the PZT via the first control module according to the mixed signal to control the movement of the fiber collimator to adjust the optical path of the first optical pulse, thereby locking the repetition frequency of the optical pulses generated by the laser generation module to the frequency of the target reference signal; and if the applied voltage of the PZT exceeds a preset voltage range, controlling the movement of the first reflective element via the second control module according to the applied 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 pulses generated by the laser generation module.

[0041] In some possible implementations, the control device further includes a filter. The method further 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 embodiments, 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, and the first preset value is the frequency adjustment amount of the repetition frequency of the light pulse corresponding to the maximum adjustment amount of the PZT loading voltage.

[0043] In some possible embodiments, 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, and the second preset value is the frequency adjustment amount of the repetition frequency of the light pulse corresponding to the minimum distance of the displacement of the first reflective element.

[0044] In some possible implementations, a frequency adjustment amount of the repetition frequency of the light pulse corresponding to the minimum displacement distance of the first reflective element is smaller than a frequency adjustment amount of the repetition frequency of the light pulse corresponding to a maximum adjustment amount of the applied voltage of the PZT.

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

[0046] In an embodiment of the present application, a laser comprises a laser generation module, a first coupler, and a reflective spatial structure consisting of at least one reflective element. The multiple laser beams generated by the laser generation module interfere in the first coupler to form light pulses, and the light pulses are divided into two paths: one first light pulse is transmitted to the reflective element, and the other second light pulse is output. The first light pulse is reflected back to the laser generation module by the reflective element. By controlling the movement of the reflective element, the optical path of the light pulse in space can be changed, thereby adjusting the repetition frequency of the light pulse generated by the laser generation module. It should be understood that controlling the movement of the reflective element can adjust the optical path of the light pulse in space, which is equivalent to multiplying the optical path of the light pulse in space, facilitating a wider range of adjustment of the repetition frequency of the light pulse. For example, a wide range of frequency modulation exceeding 2 MHz can be achieved. Furthermore, by adjusting the applied voltage of the 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 applied voltage of the PZT. While achieving frequency locking, the repetition frequency of the light pulse can be more finely adjusted, improving the adjustment accuracy of the repetition frequency and reducing the risk of frequency loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG1 is a schematic diagram of a first structure of a laser according to an embodiment of the present application;

[0048] FIG2 is a schematic diagram of a second structure of a laser according to an embodiment of the present application;

[0049] FIG3 is a schematic diagram of a third structure of a laser according to an embodiment of the present application;

[0050] FIG4 is a schematic diagram of a fourth structure of a laser according to an embodiment of the present application;

[0051] FIG5 is a schematic diagram of a fifth structure of a laser according to an embodiment of the present application;

[0052] FIG6 is a first schematic diagram of the transmission of light pulses output by the optical fiber collimator in space in an embodiment of the present application;

[0053] FIG7 is a second schematic diagram of the transmission of light pulses output by the optical fiber collimator in space in an embodiment of the present application;

[0054] FIG8 is a third schematic diagram of the transmission of light pulses output by the fiber collimator in space according to an embodiment of the present application;

[0055] FIG9 is a sixth structural diagram of a laser according to an embodiment of the present application;

[0056] FIG10 is a schematic diagram of a process for adjusting the repetition frequency of light pulses in an embodiment of the present application;

[0057] FIG11 is a schematic diagram of a seventh structure of a laser according to an embodiment of the present application;

[0058] FIG12 is a diagram showing the drift measurement results of the repetition frequency of the optical pulse in an embodiment of the present application;

[0059] FIG13 is a schematic diagram comparing the repetition frequency of optical pulses locked and unlocked in an embodiment of the present application;

[0060] FIG14 is a schematic diagram of an electrical signal phase detection device according to an embodiment of the present application;

[0061] FIG15 is an optical frequency comb device according to an embodiment of the present application;

[0062] FIG16 is a schematic diagram of an embodiment of a method for frequency modulation of optical pulses in an embodiment of the present application. DETAILED DESCRIPTION

[0063] The embodiments of the present application provide a laser and related equipment and methods. The laser includes a laser generation module, a first coupler and a reflective space structure composed of at least one reflective element. The multi-path laser generated by the laser generation module forms a light pulse through interference in the first coupler, and the light pulse is divided into two paths, one of which is a first light pulse transmitted to the reflective element, and the other is a second light pulse output. The first light pulse will be reflected back to the laser generation module by the reflective element. Controlling the movement of the reflective element can adjust the optical path of the first light pulse in space, which is equivalent to multiplying the optical path of the first light pulse in space, which is conducive to adjusting the repetition frequency of the light pulse in a wider range. It should be understood that the laser provided in the embodiments of the present application can also be called a mode-locked laser or a mode-locked fiber laser, which can generate femtosecond lasers with high stability and has a wide range of repetition frequency adjustment capabilities. It can be applied to the preparation of optical frequency combs, high-precision laser ranging, precision micromachining, optical fiber time-frequency transmission, preparation and calibration of high-precision instruments and other fields.

[0064] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, rather than to limit a specific order or precedence. It should be understood that the above terms can be interchangeable where appropriate so that the embodiments described in this application can be implemented in a sequence other than that described in this application. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. 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 clearly listed, but may include other steps or units that are not clearly 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 the embodiment of the present application. 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 pulse emitted by the laser emitting device to adjust the repetition frequency of the light pulse and achieve repetition frequency locking of the light pulse. Among them, for the sake of ease of introduction, the laser emitting device is divided into two parts: a laser body 10 and a spatial reflection module 20. This division may not exist in the actual product implementation. It should be understood that the laser emitting device needs to be sealed and vibration-isolated as a whole, and actively temperature controlled. This series of steps can reduce the parameter of repetition frequency drift to the order of magnitude below 10Hz.

[0066] Specifically, the laser body 10 includes a laser generating module 101, a first coupler 102, a second coupler 103, a piezoelectric ceramic transducer (PZT) 104 and a fiber collimator 105, and the spatial reflection module 20 includes a first reflecting element 201. The laser generating 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 light pulses, and the light pulses passing through the first coupler 102 are divided into two paths, namely, a first light pulse transmitted to the fiber collimator 105 and a second light pulse output. The second light pulse is divided into two paths through the second coupler 103. After the second light pulse is split, one of the light pulses is transmitted to the control device, and the other light pulse after the second light pulse is split is emitted outward. It should be understood that the first coupler 102 is connected to the second coupler 103 and the fiber collimator 105 respectively through optical fibers. The fiber collimator 105 collimates the input first light pulse, and the collimated first light pulse is transmitted toward the first reflective element 201 in space, 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 description, the transmission from laser generation module 101 to first reflective element 201 and back can be understood as the transmission of a light pulse within the laser's resonant cavity. The pulse interval is the time period required for a light pulse to complete one revolution within the resonant cavity, and the repetition frequency of the light pulse is the inverse of this period. Therefore, the repetition frequency of the light pulse can be adjusted by adjusting the optical path length of the light pulse within the resonant cavity. Specifically, the control device can adjust the applied voltage of PZT 104 based on the current repetition frequency of the second light pulse and the desired target frequency, and control the movement of first reflective element 201 based on the applied voltage of the PZT. The specific method for coordinating the adjustment of PZT 104 and first reflective element 201 will be described in detail below. As an example, as shown in Figure 1, PZT 104 is connected to fiber collimator 105. Adjusting the applied voltage of PZT 104 causes the PZT to extend and retract, driving the fiber collimator 105 to move, thereby changing the optical path length of the first light pulse in space and thereby adjusting the repetition frequency of the light pulse. Controlling the movement of the first reflective element 201 can also change the optical path of the first light pulse transmitted in space, and can also adjust the repetition frequency of the light pulse. It should be understood that the present application does not limit the specific method of controlling the movement of the first reflective element 201. For example, the first reflective element 201 is placed on a displacement stage, and the movement of the first reflective element 201 is driven by controlling the movement of the displacement stage. It should be noted that the present application does not limit the number of reflective elements in the spatial reflection module 20 and the size of each reflective element. The following introduces several implementation methods with multiple reflective elements, which can adjust the optical path of the light pulse in space over a larger range, which is conducive to improving the adjustment range of the repetition frequency of the light pulse.

[0068] FIG2 is a schematic diagram of a second structure of the laser in an embodiment of the present application. Different from the embodiment shown in FIG1 , as shown in FIG2 , the PZT 104 can also be connected to the optical fiber used to transmit the light pulse in the laser emitting device. For example, the PZT 104 can be connected to the optical fiber in the laser generating module 101. For another example, the PZT 104 can also be connected to the optical fiber between the first coupler 102 and the optical fiber collimator 105. The control device adjusts the applied voltage of the PZT 104 to cause the PZT to deform, thereby stretching the optical fiber, which can change the optical path of the light pulse transmitted in the optical fiber and adjust the repetition frequency of the light pulse.

[0069] FIG3 is a schematic diagram of a third structural embodiment of the laser in the embodiment of the present application. Different from the embodiment shown in FIG1 , as shown in FIG3 , the spatial reflection module 20 further includes a second reflection element 202. The first reflection element 201 reflects the first light pulse from the fiber collimator 105 to the second reflection element 202. The second reflection element 202 then reflects the first light pulse back to the first reflection element 201, and the first reflection element 201 then reflects the first light pulse back to the fiber collimator 105. It should be understood that in actual applications, the control device can control the movement of at least one of the first reflection element 201 and the second reflection element 202, provided that both the first reflection element 201 and the second reflection element 202 can receive the first light pulse. For example, the movement of the second reflection element 202 can be controlled independently. For another example, the first reflection element 201 and the second reflection element 202 can be controlled to move together.

[0070] Figure 4 is a schematic diagram of a fourth structural embodiment of the laser according to an embodiment of the present application. As shown in Figure 4 , unlike the embodiments shown in Figures 1 and 3 , the spatial reflection module 20 further includes a third reflection element 203. The first light pulse from the fiber collimator 105 is sequentially reflected by the first reflection element 201, the second reflection element 202, and the third reflection element 203 before being reflected back to the fiber collimator 105 along the original path. It should be understood that in practical applications, the control device can simply control the movement of at least one of the first, second, and third reflection elements 201, 202, and 203, while ensuring that the first, second, and third reflection elements 201, 202, and 203 can all receive the first light pulse. For example, the control device can maintain the third reflection element 203 stationary while controlling the movement of the first and second reflection elements 201 and 202. For another example, the control device can maintain the first reflection element 201 stationary while controlling the movement of the second and third reflection elements 202 and 203.

[0071] FIG5 is a schematic diagram of the fifth structure of the laser in the embodiment of the present application. As shown in FIG5 , in one possible embodiment, 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 variations. Even if the optical path of the light pulse is adjusted over a large range, the light pulse can still be continuously generated. For example, the first laser generated by the NALM is transmitted clockwise in the NALM, and the second laser generated by the NALM is transmitted clockwise in the NALM. The first laser and the second laser undergo nonlinear interference through the first coupler 102 to obtain light 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 is used to couple the pump light output by the pump source 101a to the gain fiber 101c, using a wavelength combining method. The light passing through the gain fiber 101c has a different wavelength from the light output by the pump source 101a. It should be understood that the wavelength division multiplexer 101b and the gain fiber 101c can both be considered as part of the components of the NALM. This application does not limit the specific component composition of the NALM. For example, the NALM may also include a common optical fiber connected to the gain fiber 101c. For another example, the NALM may also include a saturable absorber 101d. The gain fiber 101c may 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] FIG6 is a first schematic diagram of the transmission of a light pulse output by a fiber collimator in space in an embodiment of the present application. As shown in FIG6 , the light beam output by the fiber collimator will first contract and then diverge. The collimation distance of the fiber collimator is the distance between the spatial position and the fiber collimator when the spot size at the spatial position is the same as the initial spot size. This distance can also be referred to as the working distance of the fiber collimator. In one possible embodiment, the collimation distance of the fiber collimator is greater than the one-way distance of the first light pulse transmitted in space. In this way, the spot size of the first light pulse reflected back to the fiber collimator changes less and diffuses less than the initial spot size, which is more conducive to coupling into the optical fiber and improving the mode locking effect of the laser. Taking the structure shown in FIG1 as an example, the one-way distance of the first light pulse transmitted in space is the distance the first light pulse is transmitted from the fiber collimator 105 to the first reflective element 201. The collimation distance of the fiber collimator is greater than the maximum distance that the first reflective element 201 can move. In other words, the first reflective element 201 will not move to a position beyond the collimation distance of the fiber collimator. Taking the structure shown in Figure 2 as an example, the one-way distance of the first light pulse transmitted in space is the distance the first light pulse transmits from the fiber 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 the first light pulse transmits in space is the distance the first light pulse transmits from the fiber collimator 105 to the first reflective element 201, then to the second reflective element 202, and then to the third reflective element 203.

[0073] FIG7 is a second schematic diagram of the transmission of a light pulse output by a fiber collimator in space in an embodiment of the present application. As shown in FIG7 , a lens 204 is further provided between the fiber collimator 105 and the first reflective element 201. The lens 204 is used to perform beam shaping on the first light pulse collimated by the fiber collimator 105 to assist in collimation. Taking the scenario shown in FIG1 as an example, the spot size of the first light pulse transmitted to the first reflective element 201 through the lens 204 is the same as or similar to the initial spot size output by the fiber collimator 105. In this way, the spot size of the first light pulse reflected back to the fiber collimator varies less and diffuses less than the initial spot size, making it more conducive to coupling into the optical fiber and improving the mode locking effect of the laser. For the scenario shown in FIG2 , the lens 204 ensures that the spot size of the first light pulse transmitted to the second reflective element 202 is the same as or similar to the initial spot size output by the fiber collimator 105. For the scenario shown in FIG. 3 , the lens 204 ensures that the spot size of the first light pulse transmitted to the position of the third reflective element 203 is the same as or similar to the initial spot size output by the fiber collimator 105 .

[0074] Figure 8 is a third schematic diagram illustrating the transmission of optical pulses output by a fiber collimator in space according to an embodiment of the present application. As shown in Figure 8 , a diffractive optical element (DOE) 205 is further disposed between the fiber collimator 105 and the first reflective element 201. The DOE 205 performs a similar function to the lens 204 and will not be further described here.

[0075] FIG9 is a schematic diagram of the sixth structure of the laser according to an embodiment of the present application. As shown in FIG9 , 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 applied voltage of the PZT 104 based on the relative error to control the movement of the fiber collimator 105 to adjust the optical path length of the first optical pulse transmitted 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 the filter 303, and the mixer 304 mixes the target reference signal and the electrical signal from the photodetector 302 to obtain a mixed signal. In some possible scenarios, the first control module and the second control module may be two independent circuit boards. Alternatively, in other possible scenarios, the first control module and the second control module may be integrated together and implemented by a controller.

[0076] It should be noted that the repetition frequency of the optical pulse can be locked within the maximum adjustment range of the applied voltage of PZT 104. The maximum adjustment range of the applied voltage of PZT 104 corresponds to the maximum adjustment range of the repetition frequency of the optical pulse that can be adjusted by PZT 104. For example, the maximum range of the applied voltage of PZT 104 can be 0V to 150V or -50V to 50V. Taking the maximum range of the applied voltage of PZT 104 as an example, the maximum adjustment range of the applied voltage of PZT 104 is 0V to 150V, and the maximum adjustment range of the applied voltage of PZT 104 is 150V. The difference between the repetition frequency of the optical pulse when the applied voltage of PZT 104 is 150V and the repetition frequency of the optical pulse when the applied voltage of PZT 104 is 0V is the maximum adjustment range of the repetition frequency of the optical pulse that can be adjusted by PZT 104.

[0077] It should be understood that if the applied voltage to PZT 104 exceeds its maximum adjustment range for maintaining repetition frequency lock, the repetition frequency of the optical pulse will lose lock during the frequency modulation process, which is referred to as frequency lock. To avoid frequency lock, a control range, or a preset voltage range, can be set for the applied voltage to 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 to PZT 104 is 0V to 150V, the control range can be set to 50V to 100V. If the applied voltage to PZT 104 exceeds the control range, the second control module 306 needs to be activated. For example, if the applied voltage to PZT 104 is less than 50V or greater than 100V, it is considered to be outside the control range. The second control module 306 controls the movement of the first reflective element 201 to adjust the optical path of the first optical pulse to adjust the repetition frequency of the optical pulse, thereby compensating for the adjustment made by the first control module 305 and returning the applied voltage to PZT 104 to within the control range. That is to say, the control device adopts a serial control method for the PZT and the first reflective element, that is, the optical path of the light pulse is adjusted by controlling the PZT to achieve frequency locking. If the risk of frequency unlocking is found based on the adjustment state of the PZT, the optical path of the light pulse can be further compensated by controlling the movement of the first reflective element to avoid frequency unlocking during the frequency modulation process.

[0078] As an example, if the applied voltage to PZT 104, adjusted by first control module 305 based on the mixing signal, exceeds the control range, the optical path of the first light pulse in space may be too long, and the repetition frequency of the light pulse is at risk of losing frequency lock. Second control module 306 controls first reflective element 201 to move based on the applied voltage to PZT 104, shortening the optical path of the first light pulse in space to adjust the repetition frequency of the light pulse. The mixing signal also changes accordingly, and the applied voltage to PZT 104, adjusted by first control module 305 based on the mixing signal, returns to the control range.

[0079] It should be understood that although the first reflective element 201 has a large movable range, enabling a wide range of frequency modulation, the adjustment amplitude of the movement of the first reflective element 201 by the second control module 306 should be limited to ensure that frequency lock does not occur during the frequency modulation process. 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 of the optical pulse repetition frequency corresponding to the minimum displacement distance of the first reflective element 201 is smaller than the frequency adjustment amount of the optical pulse repetition frequency corresponding to the maximum adjustment amount of the applied voltage of the PZT 104. In other words, the accuracy of a single adjustment of the displacement of the first reflective element 201 is smaller than the maximum distance of the optical fiber collimator 105 controlled by adjusting the applied voltage of the PZT 104. As an example, the accuracy of a single adjustment of the displacement of the first reflective element 201 is 20 nm, and the range of the displacement of the first reflective element 201 is 50 mm.

[0080] It should be noted that while the optical pulse repetition frequency can be locked within the maximum adjustment range of the applied voltage on PZT 104, if the relative error between the optical pulse repetition frequency and the target frequency of the target reference signal is large, it may not be possible to lock the optical pulse repetition frequency to the target frequency by adjusting the applied voltage on PZT 104 all at once. Therefore, a frequency modulation step can be set for reference signal source 301 based on the maximum adjustment range of the applied voltage on PZT 104. By performing multiple frequency modulations on reference signal source 301, the signal output by reference signal source 301 can be adjusted to the target reference signal with the target frequency in multiple steps. A specific implementation is described below.

[0081] Figure 10 is a schematic diagram of a process for adjusting the repetition frequency of optical pulses according to an embodiment of the present application. As shown in Figure 10 , the initial frequency f0 and target frequency f1 of reference signal source 301 are first determined. Then, based on the frequency modulation step Δf of reference signal source 301, the number of steps n required for frequency modulation of reference signal source 301 to reach target frequency f1 is calculated, where n = |f1-f0| / Δf. Furthermore, each time the frequency of the reference signal output by reference signal source 301 is adjusted, the first control module 305 adjusts the applied voltage of PZT 104 based on the mixing signal to lock the frequency of the optical pulses to the frequency of the current reference signal. If the applied voltage of PZT 104 exceeds the control range, the second control module 306 controls the movement of the first reflective element 201 to return the applied voltage of PZT 104 to the control range, thereby preventing frequency loss. If the applied voltage of PZT 104 does not exceed the control range, the second control module 306 is deactivated. Repeating these steps n times completes the complete process for adjusting the repetition frequency of optical pulses.

[0082] It should be understood that the frequency modulation step Δf of the test signal source 301 cannot be too large, otherwise the frequency may be unlocked. That is, 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 the PZT 104. For example, the value range of the 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. That is, 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 reflective element 201. For example, the value range of the second preset value can be 1Hz-10Hz.

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

[0084] FIG11 is a seventh structural schematic diagram of a laser in an embodiment of the present application. Different from the laser shown in FIG1 , as shown in FIG11 , the laser emitting device further 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 provided in the laser generating module 101. The third coupler 106 adopts a one-way input and two-way output design. When the laser generating module 101 generates a stable optical pulse, the third coupler 106 can also split the optical pulse generated by the laser generating module 101. One of the split optical pulses is transmitted to the first coupler 102, and the other split optical pulse is emitted outward. Thus, the optical pulse emitted by the second coupler 103 can be combined to realize the emission of multiple optical pulses.

[0085] Figure 12 shows the measured drift of the optical pulse repetition frequency in an embodiment of the present application. As shown in Figure 12, the horizontal axis represents the measurement duration in seconds (s), and the vertical axis represents the frequency drift in millihertz (mHz). As can be seen, the measured frequency drift is approximately ±1 mHz, indicating good frequency locking.

[0086] Figure 13 shows a comparison of locked and unlocked optical pulse repetition frequency in an embodiment of the present application. As shown in Figure 13 , the horizontal axis represents duration in seconds (s), while the vertical axis represents frequency stability. As can be seen, the repetition frequency stability in seconds after locking is 0.3 MHz, demonstrating good frequency locking performance.

[0087] From the above introduction, it can be seen that the laser includes a laser generation module, a first coupler and a reflective space structure composed of at least one reflective element. The multi-path laser generated by the laser generation module forms a light pulse through interference in the first coupler, and the light pulse is divided into two paths, one of which is a first light pulse transmitted to the reflective element, and the other is a second light pulse output. The first light pulse will be reflected back to the laser generation module by the reflective element. By controlling the movement of the reflective element, the optical path of the light pulse transmitted in space can be changed, so that the repetition frequency of the light pulse generated by the laser generation module can be adjusted. It should be understood that controlling the movement of the reflective element can adjust the optical path of the light pulse in space, which is equivalent to multiplying the optical path of the light pulse in space, which is conducive to adjusting the repetition frequency of the light pulse in a wider range. For example, a large-scale optical path change exceeding 60mm can be achieved, and a large-scale frequency modulation exceeding 2MHz can be achieved. In addition, by adjusting the PZT loading voltage 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 PZT loading voltage. While achieving frequency locking, the repetition frequency of the light pulse can be adjusted more finely, thereby improving the adjustment accuracy of the repetition frequency and reducing the risk of frequency loss of lock.

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

[0089] FIG14 is a schematic diagram of an electrical signal phase detection device in an embodiment of the present application. As shown in FIG14 , the electrical signal phase detection device includes a laser, a photodetector, and a phase detector. The laser may be a laser as described in any of the above embodiments. Specifically, 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 also inputs a second electrical signal, for example, the second electrical signal may be a clock signal, etc. The phase detector is used to determine the phase difference between the first electrical signal and the second electrical signal, and output an electrical phase signal of 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 the present 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 perform spectrum expansion, frequency multiplication, and beat frequency detection on the optical pulses emitted by the laser to obtain an initial frequency signal. 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 following is an introduction to the frequency modulation method of optical pulses provided in the embodiments of the present application.

[0092] Figure 16 is a schematic diagram of an embodiment of a method for frequency modulation of optical pulses according to an embodiment of the present application. It should be noted that this method is implemented based on the laser described above. For an introduction to the laser, please refer to the relevant descriptions of the above embodiments and will not be repeated here. In this example, the method for frequency modulation of optical pulses includes the following steps.

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

[0094] Taking the laser generating 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. The first laser and the second laser are interfered with by the first coupler to obtain a light pulse.

[0096] The first laser and the second laser generate nonlinear interference through the first coupler to obtain light pulses, and the light pulses passing through the first coupler are divided into two paths, namely the first light pulse transmitted to the first reflecting element and the output second light pulse.

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

[0098] Specifically, a first light pulse from the first coupler is collimated by a fiber collimator to obtain a first light pulse transmitted in space. The first light pulse can be reflected back to the fiber collimator by a first reflective element. It should be understood that this application does not limit the number of reflective elements in space. For example, the first light pulse can also be reflected multiple times by multiple reflective 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, filters it, and mixes the filtered electrical signal with the target reference signal to generate a mixed signal. Furthermore, the control device adjusts the applied voltage of the PZT based on the mixed signal to control the fiber collimator to move or stretch the optical fiber, thereby adjusting the optical path length of the first optical pulse and locking the repetition frequency of the optical pulse to the frequency of the target reference signal.

[0101] 15. Control the movement of the first reflective element through the control device.

[0102] Specifically, the control device determines whether the applied voltage to the PZT exceeds the control range. If so, there is a risk of the repetition frequency of the light pulse being locked. In this case, the control device controls the movement of the first reflective element to adjust the optical path length of the first light pulse based on the applied voltage to adjust the repetition frequency of the light pulse so that the applied voltage to the PZT returns to the control range.

[0103] It should be noted that the above embodiments are intended only to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents; and such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A laser, characterized in that: It comprises: a laser emitting device and a control device, wherein the laser emitting device comprises a laser generating module, a first coupler and a first reflecting element; The laser generating 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 a light pulse, wherein the light pulse includes a first light pulse transmitted to the first reflecting element and an output second light pulse; 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 generating module comprises a nonlinear gain loop mirror NALM and a pump source, wherein the NALM is connected to the first coupler, the pump source is used to output pump light to the NALM, and the NALM is used to generate the first laser and the second laser according to 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, and the WDM is used to couple the pump light output by 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 further comprises a second reflecting element; The first reflecting element is used to reflect the first light pulse to the second reflecting element, and then reflect the first light pulse reflected by the second reflecting element back to the laser generating module; The control device is further used to adjust the optical path of the first light pulse by controlling the movement of the second reflecting element.

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

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

8. The laser according to claim 6 or 7, characterized in that: The laser emitting device also includes a lens or a diffractive optical element DOE, and the lens or the DOE is located between the optical fiber collimator and the first reflecting element; the lens or the DOE is used to perform beam shaping on the first light pulse from the optical fiber collimator, and transmit the beam-shaped first light pulse to the first reflecting element.

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

10. The laser according to any one of claims 1 to 9, characterized in that The second light pulse is transmitted to the control device, and the laser emitting device also includes a piezoelectric ceramic PZT, and the PZT is connected to the optical fiber in the laser generation module or the optical fiber used to transmit the first light pulse. The control device is also used to adjust the loading voltage of the PZT according to the second light pulse to control the stretching of the optical fiber to adjust the optical path of the light 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 comprises: 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 a target reference signal; The photodetector is used to convert the second light 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 loading voltage of the PZT according to the mixing signal to adjust the optical path of the first light pulse; If the applied voltage of the PZT exceeds a 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 applied 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 smaller than a first preset value, and the first preset value is the frequency adjustment amount of the repetition frequency of the light 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, and the second preset value is the frequency adjustment amount of the repetition frequency of the light pulse corresponding to the minimum distance of 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 light pulse corresponding to the minimum displacement distance of the first reflective element is smaller than the frequency adjustment amount of the repetition frequency of the light pulse corresponding to the maximum adjustment amount of the applied voltage of the PZT.

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

18. An electrical signal phase detection device, characterized in that: include: A phase detector, a photodetector and a laser as claimed 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 comprises a laser beat frequency module, an initial frequency locking module and a laser as claimed in any one of claims 1 to 17; The laser beat frequency module is used to perform spectrum expansion, frequency doubling and beat frequency detection according to the light pulse emitted by the laser to obtain an initial frequency signal; 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 optical pulses, 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 comprises: Generate a first laser and a second laser by the laser generating module; Interfering the first laser and the second laser through the first coupler to obtain a light pulse, wherein the light pulse includes a first light pulse transmitted to the first reflecting element and an output second light pulse; reflecting the first light pulse back to the laser generating module through the first reflecting element; The control device controls the movement of the first reflective element to adjust the optical path length of the first light pulse.

21. The method according to claim 20, characterized in that The laser generating module comprises a nonlinear gain loop mirror NALM and a pump source, and the method further comprises: 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. The method further includes: coupling the pump light output by the pump source to the gain fiber through the WDM.

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