An electrically regulated 2-μm-band ghz solid mode-locked device

Abstract

The application discloses a 2 mu m wave band GHz solid mode-locked device based on electric regulation, belongs to the technical field of ultrafast laser and semiconductor device, and comprises a high-brightness fiber laser pumping source, an optical focusing coupling system for focusing and collimating the pumping source, a first input mirror for transmitting and reflecting the focused laser beam, a gain medium for generating and amplifying laser, a second input mirror and a third input mirror for reflecting the focused laser beam, and a two-dimensional Bi2O2Se electro-optic modulation device for modulating the laser beam. The application develops the two-dimensional Bi2O2Se electro-optic modulation device with low saturation flux, fast saturation recovery time and moderate modulation depth, so as to break through the technical barrier of solid GHz femtosecond mode-locked.

Description

Technical Field

[0001] This invention belongs to the field of ultrafast laser technology and semiconductor device technology, and particularly relates to an electrically tunable 2µm band GHz solid-state mode-locked device. Background Technology

[0002] 2 µm-band gigahertz (GHz) high-repetition-rate ultrafast lasers hold significant promise for applications in high-capacity free-space optical communication, optical frequency combs, ultra-high-precision molecular spectroscopy, and precision polymer processing. For instance, as a crucial atmospheric transmission window, this band exhibits strong penetrating power through fog and dust. Furthermore, GHz high-repetition-rate ultrafast lasers can significantly enhance the transmission capacity of optical signal processing systems, greatly promoting the development of high-capacity free-space optical communication technology for the "last mile" of broadband networks.

[0003] There are three main ways to generate 2 µm band GHz ultrashort pulses:

[0004] The first approach involves using nonlinear frequency conversion techniques such as optical parametric oscillation (OPO) to convert mature 1 µm-band GHz ultrashort pulses to the 2 µm-band. However, the wide emission spectrum, short pulse duration, and high peak power of ultrafast lasers pose significant challenges to the strict phase matching and precise temporal synchronization of the pump light with the signal and idler light during ultrafast laser-pumped OPO processes. Furthermore, this approach is highly susceptible to optical damage to nonlinear crystal materials, resulting in complex system structures, low reliability, and short lifespan.

[0005] The second type is based on Tm 3+ Ho 3+ Doped fiber mode-locking technology. Compared with OPO technology, this technology can realize the direct output of 2 µm band GHz ultrashort pulses from the oscillator, with simple system design and high conversion efficiency. However, rare earth ion doped 2 µm band GHz ultrafast fiber lasers still face the following challenges: (1) NPR mode-locking is highly dependent on the nonlinear effect of the fiber and the polarization state of the light. Changes in the external environment temperature will cause the mode-locked laser to lose lock; (2) High-order harmonics of harmonic mode-locking are prone to cause pulse timing jitter and amplitude fluctuations, affecting the stability of the laser and beam quality; (3) It is difficult to directly obtain high-output-power fundamental frequency femtosecond pulses. The short-gain fiber required for GHz repetition rate depends on a high doping concentration. However, the current high-doped fiber technology is not mature, which can easily lead to insufficient fiber uniformity. In addition, the strong nonlinear effect, limited energy storage and low damage threshold of the fiber itself make it particularly difficult to obtain high-power 2 µm band GHz mode-locked femtosecond pulses directly from the fiber oscillator.

[0006] The third type is based on Tm 3+ Ho 3+High-power solid-state mode-locked laser technology using doped crystals. Compared to 2 µm band fiber materials, China's growth and fabrication technology for laser crystals in this band has reached an internationally leading level. These laser crystals possess characteristics such as high damage threshold, low nonlinear effects, low cost, and the ability to be highly doped, providing a strong guarantee for realizing GHz high-power mode-locked femtosecond lasers in the 2 µm band. Currently, Tm 3+ Ho 3+ Significant progress has been made in the research of solid-state mode-locked lasers with doped crystals. However, to date, there have been no reports of 2 µm-band GHz solid-state femtosecond lasers that can be mode-locked by a saturable absorber. The reasons for this are mainly due to the lack of 2 µm-band GHz solid-state mode-locking elements with low saturation flux, fast saturation recovery time, and moderate modulation depth, in addition to the immaturity of 2 µm-band short-cavity mode-locking technology.

[0007] In summary, many problems remain to be solved in the current research. The lack of solid-state mode-locking elements with low saturation flux, fast saturation recovery time, and moderate modulation depth in the 2 µm band GHz band is the main reason why it is currently difficult to realize solid-state GHz femtosecond lasers in the 2 µm band. Summary of the Invention

[0008] To address the aforementioned technical barriers, this invention proposes an electrically modulated 2 µm band GHz solid-state mode-locked device to solve the problems existing in the prior art.

[0009] To achieve the above objectives, the present invention provides an electrically modulated 2 µm band GHz solid-state mode-locked device, comprising the following structure:

[0010] A fiber laser pump source used to emit a laser beam;

[0011] A mode-locked resonant cavity includes an input mirror group and a two-dimensional electro-optic modulation device, wherein the mode-locked resonant cavity is used to reflect and modulate the laser beam;

[0012] The output mirror is used to reflect the laser back into the resonant cavity for gain amplification and to output the modulated laser beam.

[0013] The two-dimensional electro-optic modulation device is composed of two-dimensional Bi2O2Se, graphene electrodes, boron nitride insulating layer and gold electrodes;

[0014] The two-dimensional electro-optic modulation device is used to control the Fermi level of two-dimensional Bi2O2Se by applying an external electric field, thereby controlling the saturated absorption characteristics of two-dimensional Bi2O2Se.

[0015] Optionally, the input mirror group includes a first input mirror, a second input mirror, and a third input mirror;

[0016] The laser beam can be sequentially input to the two-dimensional electro-optic modulator along the first input mirror, the second input mirror and the third input mirror, and the laser beam reflected by the two-dimensional electro-optic modulator can be sequentially input to the output mirror along the third input mirror, the second input mirror and the first input mirror, and output a laser beam.

[0017] Optionally, the first input mirror and the second input mirror are both concave mirrors with a radius of curvature of 50 mm and are negative dispersion mirrors, and the third input mirror is a concave mirror with a radius of curvature of 100 mm.

[0018] Optionally, a plane mirror is also included, which is used to vertically deflect the laser beam emitted by the fiber laser pump source, and the plane mirror is placed at a 45-degree angle relative to the direction of the laser beam.

[0019] Optionally, it also includes an optical focusing coupling system, which is used to focus and collimate the laser beam emitted by the pump source of the fiber laser, and the focusing ratio of the optical focusing coupling system is 5:1.

[0020] Optionally, the fiber laser pump source is a fiber laser with a wavelength of 1700 nm.

[0021] Optionally, a laser gain medium may also be included, which is used to generate and amplify laser light.

[0022] Optionally, the laser gain medium is a Tm,Ho:CaLYLO or Tm,Ho:CALGO crystal; wherein Tm 3+ The ion doping concentration was 5 at.%, Ho 3+ The ion doping concentration was 0.5 at.%.

[0023] Optionally, the laser beam is focused onto the center of the laser gain medium after passing through the first input mirror, then reflected sequentially through the second input mirror to the third input mirror and the two-dimensional electro-optic modulator, then reflected sequentially through the two-dimensional electro-optic modulator to the third input mirror, the second input mirror and the first input mirror, and finally output through the output mirror.

[0024] This invention also provides a method for fabricating a two-dimensional Bi₂O₂Se electro-optic modulation device, used to fabricate a two-dimensional electro-optic modulation device in an electrically controlled 2 µm band GHz solid-state mode-locked device, the process comprising:

[0025] The prepared two-dimensional Bi2O2Se was transferred to the surface of a high-reflectivity end mirror;

[0026] The electrode structure was designed, the channel length was determined, and the source, drain and gate were etched using electron beam lithography.

[0027] After etching, 5 nm thick chromium and 50 nm thick gold are deposited in a vacuum environment to form a highly conductive electrode.

[0028] Boron nitride thin films were prepared by mechanical exfoliation and transferred to the surface of the electrode layer as an insulating layer.

[0029] Graphene is transferred to the top gate position using ice-assisted transfer technology to serve as the top gate electrode.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] This invention provides a 2 µm-band GHz solid-state mode-locked device based on electric field-controlled saturable absorption of two-dimensional Bi₂O₂Se. Two-dimensional Bi₂O₂Se is an excellent broadband saturable absorber material with a large nonlinear absorption coefficient, excellent air stability, ultrafast saturation recovery time, and good Fermi level tunability. The saturable absorption parameters of two-dimensional Bi₂O₂Se can be precisely controlled using an external electric field, achieving high-performance 2 µm-band GHz solid-state mode-locked laser output.

[0032] This invention selects Tm,Ho:CaLYLO or Tm,Ho:CALGO crystals as laser gain media, which have a large emission cross section and a wide emission spectrum. At the same time, it uses a high-brightness fiber laser with a wavelength of 1700 nm as the pump source, which can improve quantum efficiency and compress the mode area in the mode-locked cavity.

[0033] This invention optimizes the mode radius of the laser gain medium and the saturable absorber using an ABCD matrix, selects the classic X-shaped cavity as the mode-locked resonant cavity, and uses small-curvature concave mirrors as negative dispersion mirrors for the first and second input mirrors, which can reduce the oscillating laser modes in the gain medium and shorten the cavity length.

[0034] The device fabricated by this invention has advantages such as low saturation flux, fast saturation recovery time, and moderate modulation depth, effectively breaking through the existing technical barriers. Attached Figure Description

[0035] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0036] Figure 1 This is a schematic diagram of a solid-state mode-locking device based on Bi2O2Se saturated absorption according to an embodiment of the present invention;

[0037] Reference numerals in the figures: 1. Fiber laser pump source; 2. Plane mirror; 3. Optical focusing coupling system; 4. First input mirror; 5. Laser gain medium; 6. Second input mirror; 7. Third input mirror; 8. Two-dimensional electro-optic modulation device; 9. Output mirror. Detailed Implementation

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0040] By applying an external electric field to modulate the Fermi level of two-dimensional materials, not only can the insertion loss of devices be effectively reduced, but also the dynamics of photogenerated carriers and nonlinear absorption characteristics can be flexibly controlled, thereby achieving precise control of saturable absorption parameters (saturation recovery time, saturation flux, and modulation depth). Two-dimensional Bi₂O₂Se has been reported as an excellent broadband saturable absorber material, possessing a large nonlinear absorption coefficient, ultrafast saturation recovery time, good Fermi level tunability, and air stability. Therefore, an external electric field can be used to precisely and dynamically control the saturable absorption parameters of two-dimensional Bi₂O₂Se, offering strong parameter controllability. This allows it to meet the key modulation parameter requirements of high-power 2 µm band solid-state GHz mode-locked femtosecond lasers for saturable absorber devices.

[0041] Based on the above technical concept, this invention proposes a 2 µm band GHz solid-state mode-locked device based on electric field-controlled two-dimensional Bi2O2Se saturated absorption, develops a mode-locking element with flexibly adjustable modulation parameters, studies the 2 µm band GHz mode-locked femtosecond pulse formation mechanism, overcomes key technologies such as solid-state mode-locked laser short cavity design, and achieves efficient and stable operation of 2 µm band GHz solid-state femtosecond laser.

[0042] like Figure 1 As shown, this embodiment provides a solid-state mode-locked device based on electric field-controlled two-dimensional Bi₂O₂Se saturable absorption, comprising:

[0043] Fiber laser pump source 1, used to emit a laser beam;

[0044] The mode-locked resonant cavity includes an input mirror group and a two-dimensional electro-optic modulator 8. The mode-locked resonant cavity is used to reflect and modulate the laser beam.

[0045] Output mirror 9 is used to reflect the laser back into the resonant cavity for gain amplification and to gradually output the modulated laser beam.

[0046] The two-dimensional electro-optic modulation device 8 is composed of two-dimensional Bi2O2Se, graphene electrodes, boron nitride insulating layer and gold electrodes;

[0047] The two-dimensional electro-optic modulation device 8 is used to precisely control the saturated absorption characteristics of two-dimensional Bi2O2Se by adjusting the Fermi level through an external electric field.

[0048] Specifically, the system includes a high-brightness fiber laser pump source 1 that emits a laser beam, a plane mirror 2 that enables vertical deflection of the laser beam, an optical focusing coupling system 3 that focuses and collimates the laser beam, a first input mirror 4 that transmits and reflects the focused laser beam, a gain medium 5 that generates and amplifies the laser beam, a second input mirror 6 and a third input mirror 7 that reflect the focused laser beam, and a two-dimensional electro-optic modulator 8 that modulates the reflected laser beam. The laser resonator of the high-brightness fiber laser pump source 1 is an X-type resonator. The laser gain medium 5 is a Tm,Ho:CaLYLO or Tm,Ho:CALGO crystal. The two-dimensional electro-optic modulator 8 is made of Bi2O2Se material. The plane mirror is placed at a 45-degree angle.

[0049] The laser also includes an output mirror 9, which is used to output the target laser beam.

[0050] As an optional implementation, the input mirror group includes a first input mirror 4, a second input mirror 6, and a third input mirror 7;

[0051] The laser beam can be sequentially input to the two-dimensional electro-optic modulator 8 along the first input mirror 4, the second input mirror 6 and the third input mirror 7, and the laser beam reflected by the two-dimensional electro-optic modulator 8 can be sequentially input to the output mirror 9 along the third input mirror 7, the second input mirror 6 and the first input mirror 4 to output the laser beam.

[0052] As an optional implementation, the first input mirror 4 and the second input mirror 6 are both concave mirrors with a radius of curvature of 50 mm and are negative dispersion mirrors, and the third input mirror 7 is a concave mirror with a radius of curvature of 100 mm.

[0053] Specifically, the first input mirror 4 and the second input mirror 6 are both concave mirrors with a radius of curvature of 50 mm, and the coating parameters are: AR@1700 nm and 1900-2200 nm@HR. The third input mirror 7 is a concave mirror with a radius of curvature of 100 mm, and the coating parameters are: AR@1700 nm and 1900-2200 nm@HR. The output mirror 9 has a transmittance of 0.5% for 1900-2200 nm laser light.

[0054] As an optional implementation, a plane mirror 2 is also included, which is used to vertically deflect the laser beam emitted by the fiber laser pump source 1, and the plane mirror 2 is placed at a 45-degree angle relative to the direction of the laser beam.

[0055] As an optional implementation, it also includes an optical focusing coupling system 3, which is used to focus and collimate the laser beam emitted by the fiber laser pump source 1, and the focusing ratio of the optical focusing coupling system 3 is 5:1.

[0056] As an optional implementation, the fiber laser pump source 1 uses a 1700 nm fiber laser.

[0057] Specifically, the center wavelength of the fiber laser pump source 1 is 1700 nm, and the focusing ratio of the optical focusing coupling system 3 is 5:1. Considering the absorption loss of water vapor at 1900 nm and the thermal effect of the gain medium, this embodiment selects a laser gain medium 5 with an emission wavelength greater than 2000 nm, a large emission cross-section, and a wide emission spectrum. At the same time, a high-brightness fiber laser with a wavelength of 1700 nm is used as the pump source to improve quantum efficiency and reduce the mode area in the mode-locked cavity.

[0058] As an optional implementation, a laser gain medium 5 is also included, which is used to gain the emitted laser beam.

[0059] As an optional implementation, the laser gain medium 5 is a Tm,Ho:CaLYLO or Tm,Ho:CALGO crystal; wherein Tm 3+ The ion doping concentration was 5 at.%, Ho 3+ The ion doping concentration was 0.5 at.%.

[0060] As an optional implementation, the laser beam is focused onto the center of the laser gain medium 5 after passing through the first input mirror 4, and then reflected sequentially through the second input mirror 6 to the third input mirror 7 and the two-dimensional electro-optic modulator 8. After passing through the two-dimensional electro-optic modulator 8, the beam is reflected sequentially to the third input mirror 7, the second input mirror 6 and the first input mirror 4, and finally output through the output mirror 9.

[0061] Specifically, the laser emitted by the fiber laser pump source 1 is vertically reflected by the 45-degree plane mirror 2, focused and collimated by the optical focusing coupling system 3, and then focused to the center of the laser gain medium 5 after passing through the first input mirror 4. It is then reflected sequentially by the second input mirror 6 to the third input mirror 7 and the two-dimensional electro-optic modulator 8. After passing through the two-dimensional electro-optic modulator 8, it is reflected sequentially to the third input mirror 7, the second input mirror 6 and the first input mirror 4, and finally output through the output mirror 9.

[0062] This invention also provides a method for fabricating a two-dimensional Bi₂O₂Se electro-optic modulation device, used to fabricate a two-dimensional electro-optic modulation device in an electrically controlled 2 µm band GHz solid-state mode-locked device, the process comprising:

[0063] The prepared two-dimensional Bi2O2Se was transferred to the surface of a high-reflectivity end mirror;

[0064] The electrode structure was designed, the channel length was determined, and the source, drain and gate were etched using electron beam lithography.

[0065] After etching, 5 nm thick chromium and 50 nm thick gold are deposited in a vacuum environment to form a highly conductive electrode.

[0066] Boron nitride thin films were prepared by mechanical exfoliation and transferred to the surface of the electrode layer as an insulating layer.

[0067] Graphene is transferred to the top gate position using ice-assisted transfer technology to serve as the top gate electrode.

[0068] As an additional implementation, the two-dimensional electro-optic modulator 8 is a two-dimensional Bi2O2Se electro-optic modulator.

[0069] In this experiment, the prepared two-dimensional Bi₂O₂Se was first transferred onto a high-reflectivity end mirror. Then, a suitable electrode structure and channel length were designed. Next, the source, drain, and gate electrodes were etched using electron beam lithography. A 5 nm layer of chromium and a 50 nm layer of gold were deposited in a vacuum environment. Boron nitride was prepared as an insulating layer material using mechanical lift-off and transferred to the device via a transfer stage. Furthermore, to reduce the loss of incident light by the gold electrode, CVD-grown graphene was selected as the top gate electrode and transferred using an ice-assisted method, thus fabricating a two-dimensional electro-optic modulation device 8.

[0070] In this embodiment, the saturable absorption parameters of two-dimensional Bi2O2Se are precisely and dynamically controlled by applying an external electric field, and the position and angle of the two-dimensional electro-optic modulator 8 and the output mirror 9 are adjusted to achieve mode-locked laser output with a repetition frequency ≥1 GHz, an average power ≥300 mW, and a pulse width ≤50 fs.

[0071] In this embodiment, the prepared two-dimensional Bi₂O₂Se is first transferred onto a high-reflectivity end mirror. This step uses a precision transfer stage to peel the Bi₂O₂Se from the original substrate, ensuring its non-destructive adhesion to the surface of the high-reflectivity end mirror to guarantee its excellent optical properties. During this process, Bi₂O₂Se, as a saturable absorber, provides excellent nonlinear absorption performance in subsequent electro-optic modulation.

[0072] Next, suitable electrode structures, including the source, drain, and gate, are designed, and the channel length is determined. The design of these electrode structures will affect the electrical performance of the device; in particular, adjusting the channel length can control the electron migration rate, thereby optimizing the device's response time and controllability. After the design is completed, electron beam lithography is used to precisely etch the source, drain, and gate to form the desired electrode structure. Electron beam lithography can control pattern generation at the nanoscale, ensuring the accuracy of the electrodes and channels.

[0073] Subsequently, a vapor deposition process is performed in a vacuum environment. First, a 5 nm thick layer of chromium is deposited as an adhesion layer, followed by a 50 nm thick layer of gold, forming a highly conductive electrode structure. The role of chromium is to ensure good adhesion between the metal layer and the substrate, while gold possesses excellent conductivity.

[0074] To achieve good light transmittance and ensure gate voltage modulation effect, this embodiment uses boron nitride with a large dielectric constant as the insulating layer material. The boron nitride is prepared by mechanical exfoliation and precisely transferred onto the device using a transfer stage. The large dielectric constant of boron nitride can broaden the tuning range of the two-dimensional Bi₂O₂Se Fermi level, and the good light transmittance helps to reduce the loss of this electro-optic modulation device.

[0075] In the following steps, to reduce the loss of incident light by the gold electrode, graphene was selected as the top gate electrode in this embodiment. Graphene not only has excellent conductivity but also extremely high light transmittance, which can reduce light absorption loss and improve the photoelectric conversion efficiency of the device. Through ice-assisted transfer technology, graphene is precisely transferred to the designated location in the device, ensuring good matching with other structures.

[0076] Through the above steps, a two-dimensional electro-optic modulation device was successfully fabricated. In this example, by developing a two-dimensional Bi₂O₂Se electro-optic modulation device with low saturation flux, fast recovery time, and moderate modulation depth, high-performance 2 µm band GHz solid-state mode-locked laser operation was ultimately achieved. This laser is suitable for applications such as high-speed optical communication and ultrafast lasers.

[0077] Based on the above specific embodiments, the technical effects of the present invention can be summarized as follows:

[0078] High-efficiency optical modulation performance: By using the two-dimensional material Bi₂O₂Se as a saturable absorber, it possesses excellent nonlinear absorption characteristics. By manipulating its Fermi level with an external electric field, the parameters of the saturable absorption can be flexibly adjusted, achieving efficient modulation of the saturable absorption characteristics of two-dimensional Bi₂O₂Se, ultimately realizing GHz solid-state mode-locked laser operation in the 2 µm band. This laser meets the needs of high-speed optical communication and precision laser processing.

[0079] Low loss and high transmittance: To reduce the loss of incident light by the electrodes and insulating layer, this invention uses transparent and highly conductive graphene as the top gate electrode and boron nitride with a large dielectric constant as the insulating layer. Compared to traditional metal electrodes and the SiO2 insulating layer, the use of graphene and boron nitride significantly reduces light absorption loss, thereby improving the overall photoelectric conversion efficiency. This allows the device to maintain low energy loss when operating with high-power lasers.

[0080] Flexible and adjustable saturation absorption parameters: By using an external electric field to control the saturation absorption parameters of two-dimensional Bi2O2Se, the saturation absorption parameters of two-dimensional Bi2O2Se can be flexibly adjusted to adapt to different laser resonator types, resulting in flexible laser output parameters with strong adjustability.

[0081] In summary, this invention significantly improves the optical modulation performance and stability of mode-locked modulators. Furthermore, by optimizing the device structure and materials, it successfully overcomes the technical barrier that makes it difficult to operate solid-state mode-locked devices in the 2 µm band at GHz. This invention is suitable for applications such as high-capacity free-space optical communication and precision laser processing.

[0082] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An electrically regulated 2 pm band GHz solid mode-locked device, characterized by, The application relates to a 2-micron waveband GHz solid-state mode-locked device based on electric regulation, which comprises the following parts: a fiber laser pumping source (1) for emitting a laser beam; a plane mirror (2) for vertically deflecting the laser beam emitted by the fiber laser pumping source (1), wherein the plane mirror (2) is arranged at an angle of 45 degrees relative to the direction of the laser beam; an optical focusing coupling system (3) for focusing and collimating the laser beam emitted by the fiber laser pumping source (1); a mode-locked resonant cavity comprising an input mirror group and a two-dimensional electro-optic modulation device (8), wherein the mode-locked resonant cavity is used for reflecting and modulating the laser beam; the input mirror group comprises a first input mirror (4), a second input mirror (6) and a third input mirror (7); and an output mirror (9) for reflecting the laser back into the resonant cavity for gain amplification and partially outputting the modulated laser beam. The two-dimensional electro-optic modulation device (8) is composed of a two-dimensional Bi2O2Se, a graphene electrode, a boron nitride insulation layer and a gold electrode. The two-dimensional electro-optic modulation device (8) is used for regulating the Fermi level of the two-dimensional Bi2O2Se through an external electric field to realize regulation of the saturated absorption characteristics of the two-dimensional Bi2O2Se. The laser emitted by the fiber laser pumping source (1) is vertically reflected by the 45-degree plane mirror (2), is focused and collimated by the optical focusing coupling system (3), is gathered to the center of the laser gain medium (5) after passing through the first input mirror (4), is sequentially reflected to the third input mirror (7) and the two-dimensional electro-optic modulation device (8) after passing through the second input mirror (6), is sequentially reflected to the third input mirror (7), the second input mirror (6) and the first input mirror (4) after passing through the two-dimensional electro-optic modulation device (8), and finally is output as a 2-micron waveband GHz solid-state mode-locked laser beam through the output mirror (9). The X-shaped cavity is used as the mode-locked resonant cavity, the first input mirror (4) and the second input mirror (6) are both concave mirrors with a curvature radius of 50 mm and are negative dispersion mirrors, and the third input mirror (7) is a concave mirror with a curvature radius of 100 mm. The focusing ratio of the optical focusing coupling system (3) is 5:

1. a laser gain medium (5) for generating and amplifying a laser beam; the laser gain medium (5) is a Tm,Ho:CaLYLO or Tm,Ho:CALGO crystal; wherein Tm 3+ the ion doping concentration is 5 at.%, Ho 3+ the ion doping concentration is 0.5 at.%; The fiber laser pumping source (1) adopts a fiber laser with a wavelength of 1700 nm. The process for preparing the two-dimensional electro-optic modulation device in the 2-micron waveband GHz solid-state mode-locked device based on electric regulation comprises the following steps: transferring the prepared two-dimensional Bi2O2Se to the surface of a high-reflective end mirror; designing an electrode structure, determining a channel length, and etching the source electrode, the drain electrode and the gate electrode based on an electron beam exposure technology; after etching, evaporating 5 nm thick chromium and 50 nm thick gold in a vacuum environment to form high-conductivity electrodes; preparing a boron nitride film by a mechanical exfoliation method and transferring the boron nitride film to the surface of the electrode layer as an insulation layer; and transferring graphene to a top gate position as a top gate electrode by using an ice-assisted transfer technology. The process for preparing the two-dimensional electro-optic modulation device in the 2-micron waveband GHz solid-state mode-locked device based on electric regulation comprises the following steps: transferring the prepared two-dimensional Bi2O2Se to the surface of a high-reflective end mirror; designing an electrode structure, determining a channel length, and etching the source electrode, the drain electrode and the gate electrode based on an electron beam exposure technology; after etching, evaporating 5 nm thick chromium and 50 nm thick gold in a vacuum environment to form high-conductivity electrodes; preparing a boron nitride film by a mechanical exfoliation method and transferring the boron nitride film to the surface of the electrode layer as an insulation layer; and transferring graphene to a top gate position as a top gate electrode by using an ice-assisted transfer technology. ​ 2. The device of claim 1, wherein, ​ 3. The device of claim 1, wherein, ​ 4. A method for fabricating a two-dimensional Bi₂O₂Se electro-optic modulation device, characterized in that, ​ ​ ​ ​ ​ ​

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