Broadband spectrum mode-locked laser based on phonon auxiliary regulation and control

Abstract

The invention discloses a broadband spectrum mode-locked laser based on phonon-assisted regulation and control, which relates to the technical field of laser and comprises a pumping source, an optical coupling system and a laser resonator which are sequentially arranged along a light path, the laser resonator comprises an input mirror, a laser medium, a first cavity mirror, a second cavity mirror, a mode locking device, a dispersion element and an output mirror which are arranged in an X-shaped cavity; the laser medium is integrated with a temperature control module which is used for adjusting the crystal temperature so as to regulate and control the phonon auxiliary intensity; a spectrum is dynamically broadened through phonon-assisted temperature control, the X-type resonant cavity and dispersion management design are combined, few-period pulses are directly generated, the traditional nonlinear post-compression technology is abandoned, the structure is simplified, the stability is high, and the industrial-grade application requirement can be met.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and more particularly to a broadband spectral mode-locked laser based on phonon-assisted regulation. Background Art

[0002] Ultrashort pulse lasers with few optical cycles (2-5 optical cycles) have important applications in basic physics research, precision micromachining of non-metallic materials, biomedical diagnosis and treatment, and national defense security. The core challenge lies in directly generating ultra-wideband mode-locked spectra to support the stable output of few-cycle pulses.

[0003] The pulse width of traditional solid-state mode-locked lasers is limited by the inherent gain bandwidth of the laser medium. For example, mode-locked lasers based on Tm / Ho co-doped materials typically have a mode-locked spectral bandwidth of only about 100 nm, supporting pulse output of only about 50 fs. To achieve shorter pulses, existing technologies rely on nonlinear post-compression, but such solutions require high-power pump sources, complex optical systems, and precise dispersion compensation, resulting in bulky and expensive systems. Furthermore, they are susceptible to thermal effects at high repetition rates, significantly reducing stability.

[0004] Secondly, while optical parametric amplification or chirped pulse amplification combined with nonlinear compression can expand the optical spectrum, they suffer from fundamental flaws. For example, optical parametric amplification requires synchronous pumping with a high-energy picosecond laser, and the inefficient coupling of signal and idler light leads to insufficient energy utilization. Solutions based on nonlinear compression, on the other hand, rely on high-precision microstructured optical fibers, which have complex fabrication processes and low yields. Only a few laboratories worldwide have the production capacity. Furthermore, the need for multi-stage amplification and dispersion management further increases system complexity, making it difficult to meet the reliability and cost-effectiveness requirements of industrial-grade applications.

[0005] Existing technologies primarily expand the spectrum by statically optimizing material properties or introducing fixed-dispersion elements, but this only achieves limited gains in bandwidth and cannot be dynamically adjusted. For example, combining two sesquioxide materials can broaden the spectrum to 41 fs, but due to the fixed material properties, further expansion of the mode-locked spectrum bandwidth is impossible.

[0006] Therefore, how to design a broadband spectral mode-locked laser based on phonon-assisted regulation that can break through the material gain bandwidth limitation, directly generate an ultra-broadband mode-locked spectrum, and achieve efficient and stable output of short-cycle pulses is an urgent problem that technicians in this field need to solve. Summary of the Invention

[0007] In view of this, the present invention provides a broadband spectrally mode-locked laser based on phonon-assisted regulation. By integrating a temperature control module to precisely adjust the temperature of the laser medium, the phonon-assisted effect is utilized to break through the traditional gain bandwidth limitation and achieve ultra-broadband gain spectrum expansion. At the same time, an optimized dispersion management structure and a high-stability resonant cavity design are adopted to ensure the stable output of ultrashort pulses.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A broadband spectrally mode-locked laser based on phonon-assisted regulation, comprising a pump source, an optical coupling system, and a laser resonator sequentially arranged along an optical path;

[0010] The laser resonator includes an input mirror, a laser medium, a first cavity mirror, a second cavity mirror, a mode-locking device, a dispersion element, and an output mirror arranged in an X-shaped cavity; the laser medium is integrated with a temperature control module for adjusting the crystal temperature to control the phonon assist intensity;

[0011] The pump light output by the pump source is focused by the optical coupling system and then incident on the laser resonator. The pump light is incident on the center of the end face of the laser medium through the input mirror. The oscillating laser generated by the excitation is reflected from the first cavity mirror to the second cavity mirror in turn, and short-pulse mode locking is achieved through nonlinear modulation at the mode-locking device.

[0012] The other part of the light path passing through the input mirror is reflected multiple times by the dispersion element to achieve dispersion compensation, and then emits the laser through the output mirror.

[0013] Preferably, the pump source is a continuous laser selected from a semiconductor laser diode, a fiber laser or a solid laser, the output wavelength of which matches the absorption wavelength of the laser medium, and the pumping mode is end-face pumping.

[0014] Preferably, the optical coupling system includes a lens group consisting of a plano-convex lens and a biconvex lens, and the incident surface of the plano-convex lens and the exit surface of the biconvex lens are coated with a dielectric film with high transmittance to the pump light, with a transmittance of ≥95%.

[0015] Preferably, the input mirror is a concave mirror, the incident surface is coated with a dielectric film with high transmittance to the pump light, with a transmittance ≥ 95%, and the other side is coated with a dielectric film with a reflectivity ≥ 99% to the oscillation laser wavelength.

[0016] Preferably, the doping ions of the laser medium are selected from Nd 3 +、Yb 3 +、Er 3 +、Tm 3 + or Ho3+, the matrix material is selected from garnet, aluminate, gadolinium scandium or sesquioxide.

[0017] Preferably, the first cavity mirror and the second cavity mirror are concave mirrors, coated with a dielectric film that fully reflects the oscillating laser light with a reflectivity ≥ 99%, and the side facing the pump light is coated with a dielectric film that is highly transparent to the pump light with a transmittance ≥ 99%.

[0018] Preferably, the mode-locked device is a semiconductor saturable absorber mirror or a low-dimensional material saturable absorber, with a non-saturated loss of oscillating laser ≤1%, a reflectivity ≥97%, and a response time ≤1ps.

[0019] Preferably, the dispersive element is a chirped mirror pair or a GTI mirror; wherein the chirped mirror pair includes two offset and parallel chirped mirrors, the input light is reflected by the second chirped mirror to the first chirped mirror, and is output by the first chirped mirror after multiple reflections between the two chirped mirrors.

[0020] Preferably, the output mirror is a plane mirror coated with a dielectric film that partially reflects the oscillating laser and has a reflectivity of 50%-99%, and the side facing away from the resonant cavity is coated with an antireflection film with a transmittance of ≥99.5%.

[0021] Preferably, the temperature control module includes a temperature sensor, a heating element, a cooling element and a closed-loop controller, and the temperature adjustment range is 0 to 200°C.

[0022] It can be seen from the above technical solution that compared with the prior art, the technical solution of the present invention has the following advantages:

[0023] Beneficial effects:

[0024] 1. It precisely regulates the temperature of the laser medium through an integrated temperature control module, and uses the phonon-assisted effect to control the phonon-electron coupling intensity of fluorescence, breaking through the inherent gain bandwidth limitations of traditional laser media; through temperature control, it can achieve coherent locking of multiple longitudinal modes inside and outside the fluorescence spectrum, significantly expanding the locking spectrum bandwidth, and providing the necessary spectral support for directly generating pulses with few optical cycles.

[0025] 2. An X-shaped laser resonator layout, combined with dispersion-compensating elements such as chirped mirror pairs or GTI mirrors, precisely controls the total group delay dispersion within the cavity (near zero or negative), ensuring time-domain compression and stable output of ultrashort pulses. By optimizing the number of reflections and compensating for second-order and higher-order dispersion using multiple chirped mirror pairs, precise management of dispersion is achieved. Furthermore, the X-shaped cavity structure optimizes the mode matching between the pump light and the oscillator laser through a dual-waist design, significantly improving the stability of the mode-locking process and pulse quality.

[0026] 3. Through the synergistic effect of the temperature control module and the mode-locking device, combined with the nonlinear broadening effect of the laser medium itself, short-cycle pulses can be directly generated without the need for additional nonlinear post-compression devices. The fixed combination of optical components and the limited number of controllable variables in the laser resonator make the system compact, easy to operate, and simple to integrate. In addition, the compatible design of the laser medium and the mode-locking device further reduces process complexity, providing a technical foundation for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0028] Figure 1 A broadband spectrally mode-locked laser based on phonon-assisted control and a schematic structural diagram provided in an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of the chirped mirror pair structure provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] Example 1;

[0032] like Figure 1 As shown, this embodiment provides a broadband spectrally mode-locked laser based on phonon-assisted regulation, comprising a pump source 1, an optical coupling system 2, and a laser resonator 3 sequentially arranged along an optical path;

[0033] The laser resonator 3 includes an input mirror 4, a laser medium 5, a first cavity mirror 6, a second cavity mirror 7, a mode-locking device 8, a dispersion element 9, and an output mirror 10 arranged in an X-shaped cavity; the laser medium 5 is integrated with a temperature control module for adjusting the crystal temperature to control the phonon assist intensity;

[0034] The pump light output by the pump source 1 is focused by the optical coupling system 2 and then incident on the laser resonator 3. The pump light is incident on the center of the end face of the laser medium 5 through the input mirror 4. The oscillating laser generated by the excitation is reflected by the first cavity mirror 6 to the second cavity mirror 7 in turn, and short-pulse mode locking is achieved through nonlinear modulation at the mode-locking device 8.

[0035] The other part of the light path passing through the input mirror 4 is reflected multiple times by the dispersive element 9 to achieve dispersion compensation, and is emitted from the laser through the output mirror 10.

[0036] It dynamically regulates the phonon-assisted effect of the laser medium through a temperature control module, breaking through the inherent gain bandwidth limitation of the material and realizing the direct generation of ultra-wideband mode-locked spectra; combined with the dispersion management design of the X-type resonant cavity and chirped mirror pair, it accurately compensates for high-order dispersion to stably output few-cycle pulses; compared with nonlinear post-compression technology, it significantly reduces complexity through structural optimization, combines high stability with practical potential, and provides an efficient solution for industrial-grade few-cycle laser applications.

[0037] The following is a further detailed description of the various components of the above laser;

[0038] In this embodiment, the pump source 1 is a continuous laser selected from a semiconductor laser diode, a fiber laser or a solid laser, whose output wavelength matches the absorption wavelength of the laser medium 5, and the pumping mode is end-face pumping;

[0039] The pump source here is highly efficient and stable, and can provide stable and continuous pump light. In particular, the output wavelength of the pump light source needs to match the absorption peak of the laser medium 5 to ensure the highest energy conversion efficiency; and the end-face pumping method directly focuses the pump light onto one end face of the laser medium, which can achieve efficient energy transmission and help form a uniform gain distribution.

[0040] In this embodiment, the optical coupling system 2 includes a lens group consisting of a plano-convex lens and a biconvex lens, and the incident surface of the plano-convex lens and the exit surface of the biconvex lens are coated with a dielectric film with high transmittance to the pump light, with a transmittance of ≥95%;

[0041] The lens assembly here focuses the pump light from the fiber output to the laser medium, while also correcting aberrations. A plano-convex lens collimates the diverging light, while a biconvex lens further focuses it. The coating design reduces interfacial reflection losses, ensuring efficient transmission of pump light energy to the laser medium.

[0042] In this embodiment, the input mirror 4 is a concave mirror, the incident surface of which is coated with a dielectric film with high transmittance to the pump light, with a transmittance of ≥95%, and the other side is coated with a dielectric film with a reflectivity of ≥99% to the oscillation laser wavelength;

[0043] The function of input mirror 4 is to separate the pump light from the oscillating laser. The concave mirror can focus the pump light onto the end face of the laser medium. At the same time, the high-reflection film ensures that the oscillating laser is reflected back into the resonant cavity to avoid energy leakage, thereby physically isolating the optical paths of the pump light and the oscillating laser.

[0044] In this embodiment, the doping ions of the laser medium 5 are selected from Nd 3 +、Yb 3 +、Er 3 +、Tm 3 + or Ho3+, the matrix material is selected from garnet, aluminate, gadolinium scandium or sesquioxide;

[0045] The doped ions here can determine the laser wavelength, such as Yb 3 + corresponds to the 1 μm band, and the matrix material affects the phonon energy and thermal conductivity; for example, Yb:CALGO crystals have medium to low phonon energy (~700-750 cm -1 ) and a higher Huang-Kun factor, which can broaden the fluorescence bandwidth through the phonon-assisted effect. At the same time, its high thermal conductivity, combined with the temperature control module, can quickly dissipate heat and maintain temperature uniformity.

[0046] In this embodiment, the first cavity mirror 6 and the second cavity mirror 7 are concave mirrors, which are coated with a dielectric film that fully reflects the oscillating laser and has a reflectivity of ≥99%, and the side facing the pump light is coated with a dielectric film that is highly transparent to the pump light and has a transmittance of ≥99%; the fully reflective film of the cavity mirror at this location ensures that the oscillating laser circulates in the resonant cavity, while the high-transmittance film allows the pump light to pass through without loss.

[0047] In this embodiment, the mode-locked device 8 is a semiconductor saturable absorber mirror or a low-dimensional material saturable absorber, with a non-saturated loss of oscillating laser ≤1%, a reflectivity ≥97%, and a response time ≤1ps;

[0048] Here, the semiconductor saturable absorber mirror filters high-intensity pulses through its nonlinear absorption characteristics. When the pulse peak power exceeds the saturation threshold, the absorption rate decreases and the reflectivity increases, forming a shutter effect in which the pulse front is preferentially reflected.

[0049] In this embodiment, the dispersion element 9 is a chirped mirror pair or a GTI mirror;

[0050] like Figure 2 As shown in the figure, the chirped mirror pair consists of two offset and parallel chirped mirrors. The input light is reflected by the second chirped mirror to the first chirped mirror. After multiple reflections between the two chirped mirrors, it is output by the first chirped mirror. The chirped mirror provides negative group delay dispersion through a multi-layer dielectric film design to compensate for the positive dispersion introduced by the laser medium and cavity mirrors, making the net dispersion in the cavity close to zero and ensuring that the pulse time domain is compressed to near the Fourier limit.

[0051] Furthermore, when the dispersion element 9 adopts a GTI mirror, a multi-layer dielectric film structure is used to provide precise negative group delay dispersion to compensate for the positive dispersion accumulated in the laser resonator. The GTI mirror is composed of a highly reflective substrate and a top partially reflective dielectric film, forming a Fabry-Perot interference structure. The incident light undergoes multiple reflections between the top film and the substrate, and different wavelength components produce phase delay differences due to the interference effect, resulting in group delay dispersion. By adjusting the film thickness and refractive index distribution, the dispersion characteristics of the GTI mirror can be customized to provide stable negative dispersion in the target band.

[0052] In specific implementation, the GTI mirror is inserted into one arm of the X-shaped cavity at a specific angle, and sufficient negative dispersion is accumulated through multiple reflections to make the total dispersion in the resonant cavity close to zero or negative, thereby suppressing pulse broadening and compressing the pulse width to at least the period level.

[0053] In this embodiment, the output mirror 10 is a plane mirror coated with a dielectric film that partially reflects the oscillating laser light, with a reflectivity of 50%-99%, and an antireflection film is coated on the side facing away from the resonant cavity, with a transmittance of ≥99.5%. The partially reflective film is used to balance the intracavity gain and output energy, and the antireflection film reduces reflection losses on the output surface.

[0054] In this embodiment, the temperature control module includes a temperature sensor, a heating element, a cooling element and a closed-loop controller, and the temperature adjustment range is 0-200°C.

[0055] Here we further explain the principle of temperature control on the phonon-assisted effect:

[0056] Temperature control directly affects the phonon-electron coupling strength by changing the energy distribution of lattice vibrations. When the crystal temperature rises, the phonon occupancy number increases, enhancing the Stokes and Anti-Stokes scattering probabilities, and causing the fluorescence spectrum to expand toward long and short wavelengths. At the same time, increasing the temperature can reduce the suppression of fluorescence transitions by lattice defects and improve gain uniformity. Closed-loop temperature control ensures the stability of the phonon-assisted intensity and avoids spectral fluctuations caused by temperature drift, thereby ensuring the long-term stability and repeatability of the ultra-wideband mode-locked spectrum.

[0057] Specifically, the temperature control module can be integrated with the laser medium 5 through mechanical packaging and heat conduction optimization. Its heating and cooling elements can be directly attached to the side or end face of the laser crystal, and thermal coupling efficiency is ensured by high thermal conductivity silver glue or metal heat sink. The temperature sensor is embedded in the near-surface area of the crystal to monitor the temperature distribution in real time. The laser medium is wrapped with an insulating layer to reduce environmental thermal interference. The closed-loop controller receives sensor signals through a multi-channel data acquisition module and dynamically adjusts the heating / cooling power to achieve full-area temperature uniformity control.

[0058] In practice, the closed-loop controller uses a PID algorithm to achieve precise temperature control. After the user sets a target temperature, a sensor provides real-time feedback of the crystal temperature to the controller. The controller then calculates the deviation between the current temperature and the set point and outputs a PWM signal to drive the heating or cooling element. For example, when the temperature falls below the set point, the Peltier chip is powered for heating; otherwise, cooling mode is activated. The temperature control cycle is ≤10ms, and power is dynamically adjusted to match changes in the thermal load. Through calibration and feedback optimization, the system achieves a steady-state temperature control accuracy of ±0.1°C within the 0-200°C range, with a standard deviation of temperature fluctuation of ≤0.05°C.

[0059] This embodiment provides a broadband spectrally mode-locked laser based on phonon-assisted regulation. By integrating a temperature control module, dynamic regulation of the phonon-electron coupling strength in the laser medium is achieved, significantly expanding the gain bandwidth and supporting the direct generation of ultrashort, short-period pulses. Combining an X-shaped resonant cavity structure with a chirped mirror pair or GTI mirror dispersion management design effectively compensates for high-order dispersion, improving mode-locking stability and pulse quality. The system has a compact structure, requires no nonlinear compression elements, and relies solely on temperature regulation and commercially available components, demonstrating excellent practicality and industrialization prospects.

[0060] Example 2;

[0061] The laser used in this implementation is a 2μm-band phonon-assisted mode-locked laser based on a Tm:GdScO3 crystal. Its core component configuration and parameters include:

[0062] Laser medium: Holmium (Tm 3+ ) gadolinium-doped scandium crystal (Tm:GdScO3) with a doping concentration of 2 at.%, a crystal size of 3 mm × 3 mm × 4 mm, and an antireflection coating (transmittance ≥ 99.5%) for the 1700 nm pump light band on both ends. The absorption length is optimized to 4 mm to match the pump light absorption efficiency;

[0063] Pump source: Thulium-doped fiber laser (Tm: fiber laser) with an output wavelength of 1700nm, a maximum output power of 15W, and a beam quality of M 2 <1.2, the pump light is injected into the Tm:GdScO3 crystal by end-face pumping;

[0064] Optical coupling system: Consists of a plano-convex lens (focal length 250mm) and a biconvex lens (focal length 75mm). The lens surface is coated with a 1700nm anti-reflection coating (transmittance ≥ 95%). It reduces the pump beam waist from 100μm at the fiber output end to 30μm at the center of the crystal end face.

[0065] Resonant cavity design: adopts X-shaped cavity structure, the specific components are as follows:

[0066] Input mirror: concave mirror (curvature radius 100mm), the incident side is coated with 1700nm high-transmittance film, and the other side is coated with high-reflection film for oscillating laser (1950-2200nm);

[0067] The first cavity mirror and the second cavity mirror are concave mirrors (curvature radius 100mm), coated with 1950-2200nm total reflection film, and the side facing the pump light is coated with 1700nm high transmittance film;

[0068] Dispersion element: Chirped mirror pairs are used. Each pair contains two chirped mirrors. The light path reflects four times between the mirrors. The total compensation GDD is -400fs. 2 , balancing the positive material dispersion of Tm:GdScO3 crystals;

[0069] Mode-locked device: semiconductor saturable absorber mirror, with reflectivity ≥98% in the 1950-2200nm band, non-saturation loss ≤0.8%, and response time ≤1ps;

[0070] Output mirror (M4): plane mirror, coated with 1950-2200nm partial reflection film (reflectivity 80%), and anti-reflection film (transmittance ≥ 99.8%) on the back surface of the cavity;

[0071] Temperature control module: Integrated on the side of the Tm:GdScO3 crystal, using a Peltier chip and a Pt100 temperature sensor, with a closed-loop temperature control range of 20 to 150°C and an accuracy of ±0.1°C. The crystal is encapsulated in a copper heat sink and covered with an aluminum nitride ceramic insulation layer to ensure an axial temperature gradient of ≤0.03°C / mm.

[0072] The working process is as follows:

[0073] First, a thulium-doped fiber laser is used as a pump source to output pump light with a wavelength of 1700nm. Through an optical coupling system consisting of a plano-convex lens and a biconvex lens, the pump beam waist is narrowed from 100μm at the output end of the fiber to 30μm at the center of the crystal end face, and then efficiently injected into the Tm:GdScO3 crystal. The pump light is absorbed in the crystal and converted into oscillating laser energy, exciting the Tm 3 The + ions generate fluorescence in the 2μm band. The oscillating laser then undergoes multiple reflections within the X-shaped cavity structure. Through precise control of the input mirror, the first cavity mirror, the second cavity mirror, and the dispersion element, dispersion compensation and spectral broadening are achieved. In particular, the chirped mirror pair, acting as a dispersion element, balances the positive material dispersion of the Tm:GdScO3 crystal through multiple reflections, ensuring stable ultrashort pulse output.

[0074] Within the resonant cavity, the mode-locking device and the semiconductor saturable absorber mirror play a key role. They exhibit high reflectivity (≥98%) and low non-saturation loss (≤0.8%) for oscillating lasers in the 1950-2200nm band, while also offering an extremely short response time (≤500fs), effectively achieving mode-locking of ultrashort pulses. Ultimately, after partial reflection from the output mirror, stable 2μm-band ultrashort pulse laser light is output from the laser. The anti-reflection coating on the back-facing cavity surface ensures high transmittance (≥99.8%), minimizing output laser losses.

[0075] In summary, the 2μm-band phonon-assisted mode-locked laser based on Tm:GdScO3 crystals in this embodiment achieves efficient and stable ultrashort pulse laser output through precise component configuration and parameter optimization. This laser not only boasts a wide spectrum and high power, but also boasts a compact structure and ease of integration, providing a powerful tool for research and application in related fields.

[0076] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. References to the same or similar parts between the various embodiments are sufficient. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For relevant parts, refer to the method description.

[0077] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A broadband spectrally mode-locked laser based on phonon-assisted control, characterized in that: It comprises a pump source (1), an optical coupling system (2) and a laser resonator (3) which are sequentially arranged along an optical path; The laser resonator (3) comprises an input mirror (4) arranged in an X-shaped cavity, a laser medium (5), a first cavity mirror (6), a second cavity mirror (7), a mode-locking device (8), a dispersion element (9), and an output mirror (10); the laser medium (5) is integrated with a temperature control module for adjusting the crystal temperature to control the phonon auxiliary intensity; The pump light output by the pump source (1) is focused by the optical coupling system (2) and then incident on the laser resonator (3). The pump light is incident on the end face center of the laser medium (5) through the input mirror (4). The oscillating laser generated by the excitation is reflected by the first cavity mirror (6) to the second cavity mirror (7) in turn, and short pulse mode locking is achieved by nonlinear modulation at the mode locking device (8). Another part of the light path passing through the input mirror (4) is reflected multiple times by the dispersion element (9) to achieve dispersion compensation, and then emitted from the laser through the output mirror (10).

2. A broadband spectrally mode-locked laser based on phonon-assisted control according to claim 1, characterized in that: The pump source (1) is a continuous laser selected from a semiconductor laser diode, a fiber laser or a solid laser, the output wavelength of which matches the absorption wavelength of the laser medium (5), and the pumping mode is end-face pumping.

3. The broadband spectrally mode-locked laser based on phonon-assisted control according to claim 1, characterized in that: The optical coupling system (2) comprises a lens group consisting of a plano-convex lens and a biconvex lens, and the incident surface of the plano-convex lens and the exit surface of the biconvex lens are plated with a medium film with high transmittance to pump light, with a transmittance of ≥95%.

4. The broadband spectrally mode-locked laser based on phonon-assisted control according to claim 1, characterized in that: The input mirror (4) is a concave mirror, the incident surface of which is coated with a dielectric film with high transmittance to pump light and a transmittance of ≥95%, and the other side of which is coated with a dielectric film with a reflectivity of ≥99% to the oscillation laser wavelength.

5. The broadband spectrally mode-locked laser based on phonon-assisted control according to claim 1, characterized in that: The doping ions of the laser medium (5) are selected from Nd 3 +、Yb 3 +、Er 3 +、Tm 3 + or Ho3+, the matrix material is selected from garnet, aluminate, gadolinium scandium or sesquioxide.

6. The broadband spectrally mode-locked laser based on phonon-assisted control according to claim 1, characterized in that: The first cavity mirror (6) and the second cavity mirror (7) are concave mirrors, coated with a dielectric film that fully reflects the oscillating laser, with a reflectivity of ≥99%, and the side facing the pump light is coated with a dielectric film that is highly transparent to the pump light, with a transmittance of ≥99%.

7. The broadband spectrally mode-locked laser based on phonon-assisted control according to claim 1, characterized in that: The mode-locked device (8) is a semiconductor saturable absorber mirror or a low-dimensional material saturable absorber, and has a non-saturated loss of oscillating laser of ≤1%, a reflectivity of ≥97%, and a response time of ≤1ps.

8. The broadband spectrally mode-locked laser based on phonon-assisted control according to claim 1, characterized in that: The dispersion element (9) is a chirped mirror pair or a GTI mirror; wherein the chirped mirror pair comprises two chirped mirrors that are offset and arranged in parallel, and the input light is reflected from the second chirped mirror to the first chirped mirror, and is output from the first chirped mirror after multiple reflections between the two chirped mirrors.

9. The broadband spectrally mode-locked laser based on phonon-assisted control according to claim 1, characterized in that: The output mirror (10) is a plane mirror coated with a dielectric film that partially reflects the oscillating laser light, with a reflectivity of 50%-99%, and a side facing away from the resonant cavity is coated with an antireflection film, with a transmittance of ≥99.5%.

10. The broadband spectrally mode-locked laser based on phonon-assisted control according to claim 1, characterized in that: The temperature control module includes a temperature sensor, a heating element, a cooling element and a closed-loop controller, and the temperature adjustment range is 0-200°C.

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