Ultra-high frequency ultrafast laser system with adjustable repetition rate

Abstract

The invention discloses an ultra-high frequency ultrafast laser system with adjustable repetition frequency, comprising: arranged in sequence on the optical path: a 100 MHz repetition frequency ultrafast seed source, an AOD acousto-optic deflector connected with a frequency conversion radio frequency control system, a collimating beam splitting optical system, a focusing lens array, an optical fiber array, an optical fiber repetition frequency multiplication system, a VOA adjustable attenuation system, a combiner beam combiner, an AO-picker frequency selector, a gain optical fiber amplification system, a multi-stage solid amplification system, an electro-optic or acousto-optic waveform modulator, and an output light spot shaping system. It can realize ultra-high frequency ultrafast laser output, from GHz to hundreds of GHz ultra-high repetition frequency, and can also realize fast repetition frequency adjustment switching, and the switching frequency can reach hundreds of Khz to Mhz.

Description

Technical Field

[0001] The invention relates to the field of optics and laser technology, and in particular to an ultra-high frequency ultrafast laser system with adjustable repetition frequency. Background Art

[0002] Lasers, especially ultrafast lasers, have the characteristics of ultrashort pulse width and high pulse peak power. Their pulse width can be compared with the time of electro-optical relaxation, which is short enough to "cold" ablate materials, reduce damage to workpieces, maintain the integrity of workpieces, and achieve processing accuracy of micrometer scale. They have obvious advantages in micro-nano ultra-fine processing of heat-sensitive materials, flammable materials, ceramics, glass, plastics, etc., and can be widely used in the field of industrial fine processing. Ultrafast lasers are generally defined as lasers with pulse widths of picoseconds or smaller. The ultrafast lasers currently on the market and in relatively mature commercial use mainly include picosecond ultrafast lasers with pulse widths of picoseconds and femtosecond ultrafast lasers with pulse widths of femtoseconds.

[0003] High repetition rate ultrashort pulse lasers have important applications in ultrafast optical imaging and special material processing. Compared with low repetition rate laser sources, the use of high repetition rate laser sources in biological tissue imaging detection can increase imaging speed and improve imaging quality, and the lower single pulse energy can reduce damage to biological tissues; in the use of high repetition rate ultrafast lasers for material processing, ultrashort pulse lasers with repetition rates of GHz to hundreds of Ghz are used to remove hard materials such as silicon and copper and soft materials such as hydrogels and mouse brain tissue. With the frequency selector, the ultrahigh frequency ultrafast laser of hundreds of Ghz is modulated to simultaneously generate pulse envelopes with a high generation period of Mhz to Khz, generating mixed pulses. This type of pulse has the characteristics of picosecond and femtosecond pulses, as well as some characteristics of ns pulses, and has high efficiency and high quality effects on the processing of special materials.

[0004] The generation of high-frequency signals in commercial picosecond and femtosecond ultrafast lasers is mainly achieved by the structural design of the seed source. The more mature seed source currently uses SESAM semiconductor saturated absorbers as passive mode-locking elements, and designs fiber resonant cavities to produce passive mode-locked laser output. The repetition frequency F of the output pulse of the passive mode-locked laser is determined by the following formula:

[0005] F = c / 2nL, (1)

[0006] c is the speed of light, n is the effective refractive index of the laser cavity, and L is the effective cavity length of the laser cavity.

[0007] Obviously, to obtain a high repetition rate, the laser cavity length needs to be shortened. However, in order to achieve stable mode-locked pulses in a passively mode-locked laser, the optical pulse energy must be high enough. In a very short cavity, the length of the gain fiber limits the intracavity gain, making it difficult to obtain very stable high repetition rate mode-locked laser pulses.

[0008] According to formula (1), in the fiber system, n=1.45, c=3*10^8m / s, if you need to obtain a laser output with a repetition frequency of 1Ghz, you need L=10.3cm, which is already a very extreme limit for the fiber system. Currently, this type of laser is only tested in experimental research, and its stability and reliability are poor, and it cannot be commercially used. If you want to obtain a laser output with a repetition frequency of 10Gh or 100Ghz, the cavity length needs to be 1.03cm and 0.103cm respectively, which is obviously impossible to achieve.

[0009] Another method to achieve ultra-fast pulse output with ultra-high repetition rate is to use direct electrical modulation of semiconductor lasers, or to add an electro-optical modulator after the semiconductor laser to modulate the ultra-short pulses. At present, direct electrical modulation of semiconductors can achieve picosecond pulses with a repetition rate of hundreds of megahertz. The method of adding an electro-optical modulator after the semiconductor laser to modulate the pulse can achieve Ghz laser pulses of hundreds of picoseconds. The narrower pulse width of these two methods means very small pulse energy, generally to the order of fJ, and worse signal-to-noise ratio; higher repetition frequency means worse stability, the back-end amplification system is too complicated, and the noise is large and the stability is poor.

[0010] In many applications, especially industrial processing lasers, different repetition frequencies of laser pulses are required when dealing with different materials or processing techniques, or different processing areas of the same processing device, and ultra-high frequency ultrafast lasers with rapidly adjustable repetition frequencies are required. In ultra-high frequency, especially Ghz to 100 Ghz, or even higher repetition frequency ultrafast lasers, it is very difficult to achieve ultra-high frequency output and rapidly adjustable repetition frequency at the same time, and it is currently difficult to commercialize. Summary of the invention

[0011] The present invention aims at the technical problem that some current technologies have technical defects and cannot be used in commercial lasers, and cannot realize ultra-high frequency ultra-fast laser output with adjustable repetition frequency. The present invention proposes an ultra-high frequency ultra-fast laser system with adjustable repetition frequency, which improves and solves the shortcomings and defects of the existing technologies with an innovative structure, realizes ultra-high frequency ultra-fast laser output, and ultra-high repetition frequency from GHz to hundreds of GHz. At the same time, it can also realize fast repetition frequency adjustment switching, and the switching frequency can reach hundreds of kHz to MHz.

[0012] To achieve the above object, the present invention adopts the following technical solutions:

[0013] A repetition frequency adjustable ultra-high frequency ultrafast laser system, characterized in that it comprises: arranged in sequence on the optical path: a 100 MHz repetition frequency ultrafast seed source, an AOD acousto-optic deflector connected to a frequency conversion radio frequency control system, a collimating beam splitting optical system, a focusing lens array, an optical fiber array, an optical fiber repetition frequency multiplication system, a VOA adjustable attenuation system, a Combiner beam combiner, an AO-picker frequency selector, a gain optical fiber amplification system, a multi-stage solid amplification system, an electro-optic or acousto-optic waveform modulator, and an output light spot shaping system.

[0014] Furthermore, a fiber pulse width stretching system is provided between the AO-picker frequency selector and the gain fiber amplification system; and a spatial pulse width compression system is provided between the multi-stage solid-state amplification system and the electro-optic or acousto-optic waveform modulator.

[0015] Furthermore, the 100 MHz repetition rate ultrafast seed source is connected to the output of the optical fiber collimator and then incident on the AOD acousto-optic deflector. The beam waist is located at the AOD output end. The AOD provides signals of different RF frequencies through a variable frequency RF control system to achieve different diffraction angles, corresponding to different output angles of the AOD.

[0016] The AOD acousto-optic deflector is connected to a collimating beam splitting optical system, and the distance between the AOD and the AOD is set to its front effective focal length d;

[0017] The collimating beam splitting optical system is connected to a focusing lens array to focus and couple the light at different angles after the AOD into the optical fiber array. The focusing lens array and the optical fiber array include n channels.

[0018] The optical fiber array is connected to an optical fiber repetition rate multiplication system, wherein each optical fiber is connected to an optical fiber repetition rate multiplier, and the ultrafast seed source signal is controlled to enter the optical fiber repetition rate multipliers of different channels by controlling the radio frequency power of the AOD system, so as to realize rapid adjustment and switching between different repetition pulses;

[0019] The optical fiber repetition rate multiplication system is connected to the VOA adjustable attenuation system through optical fiber, and the insertion loss of each VOA is adjusted according to the laser power output by each optical fiber repetition rate multiplier, so as to achieve the same average power output of each channel or obtain the required power output;

[0020] The VOA adjustable attenuation system is then fused with a combiner to couple the signal lights of each channel into an optical fiber, and then fused with an AO-picker to modulate the ultra-high frequency signals of each channel to achieve the output of ultra-high frequency picosecond / femtosecond pulse trains with a width of nanoseconds to milliseconds and a frequency of hundreds of GHz.

[0021] Furthermore, the gain fiber amplification system and the multi-stage solid amplification system respectively use gain fiber and solid gain medium to amplify the signal light, and amplify the nJ / uJ signal light to hundreds of uJ / mJ single pulse energy; the waveform modulator is used to realize the switching and modulation functions of the output amplified ultrafast laser, and the output spot shaping system shapes the output spot to the required spot size and divergence angle.

[0022] Furthermore, the Combiner is connected to a fiber pulse width stretching system to use dispersion delay to stretch the pulse width for subsequent amplification; the spatial pulse width compression system uses a dispersion compensation spatial grating system to compress the stretched pulse back into a picosecond / femtosecond pulse.

[0023] Furthermore, the 100 MHz repetition rate ultrafast seed source adopts a SESAM passive mode-locked ultrafast seed source;

[0024] The optical fiber repetition rate multiplication system adopts a 7-channel system to achieve 8 times, 16 times, 32 times, 64 times, 128 times, 256 times, and 512 times repetition frequency increases respectively. Corresponding to a 200Mhz seed source, it achieves 1.6Ghz, 3.2Ghz, 6.4Ghz, 12.8Ghz, 25.6Ghz, 51.2Ghz, and 102.4Ghz high repetition frequency outputs respectively; in actual applications, it may not be limited to 7 channels, and the number of channels may be increased or decreased according to actual needs.

[0025] The AOD acousto-optic deflector uses a conversion frequency of 72.5Mhz-107.5Mhz to achieve an angle change in the range of 3.2 degrees; the deflection angle interval of each channel corresponding to the 7 channels is 0.53 degrees; in practical applications, AOD acousto-optic deflectors with other frequencies and deflection angle parameters can also be selected according to system needs.

[0026] The focusing lens array adopts a 7-channel microlens array, the optical fiber array adopts a 7-channel optical fiber array, and the optical fiber adopts a single-mode or quasi-single-mode polarization-maintaining or non-polarization-maintaining optical fiber; in practical applications, it is not limited to 7 channels, and the number of channels can be increased or decreased according to actual needs.

[0027] The VOA adjustable attenuation system adopts 7-channel optical fiber electrically adjustable attenuators, electronically controls the loss of each channel, and performs dynamic control by accessing a feedback system, so that the average output power or single pulse energy remains unchanged when the repetition frequency is adjusted and switched; in actual applications, it may not be limited to 7 channels, and the number of channels may be increased or decreased according to actual needs.

[0028] The Combiner uses a 7-in-1 combiner to couple 7 optical signals into the same optical fiber. In practical applications, it is not limited to the 7-in-1 combiner, and the number of combining channels can be increased or decreased according to actual needs.

[0029] Furthermore, the AO-picker frequency selector adopts a 200Mhz frequency AO-picker to generate a ns to ms width pulse train within a 50Mhz modulation frequency; in practical applications, it may not be limited to a 200Mhz AO-picker, and an AO-picker of other frequencies may be selected according to the frequency selection speed requirements.

[0030] The gain fiber amplification system adopts selective Yb-doped gain fiber and 975nm / 915nm pump source to pre-amplify the seed signal laser to achieve 10-20 times gain amplification;

[0031] The multi-stage solid amplification system adopts Nd:YVO4 / Nd:YAG as the gain medium, 878nm / 808nm pump source, and multi-stage gain amplification to achieve 100-1000 times gain amplification;

[0032] The waveform modulator adopts 80Mhz AOQS acousto-optic modulator to switch and modulate the output laser. In practical applications, AOQS of other frequencies can also be selected as needed.

[0033] Furthermore, each repetition frequency multiplier in the optical fiber repetition frequency multiplication system uses the principle of optical path phase delay to split a beam of light with a repetition frequency of f into two paths, and by controlling the optical path difference between the two paths, one path is delayed by half a repetition frequency cycle compared to the other path, and then the beams are combined to achieve a 2f repetition frequency output; through multiple beam splitting, delaying, and beam combining, 2f, 4f, 8f...2 n Repetitive frequency output to achieve 100 GHz repetition frequency pulse output.

[0034] Furthermore, the fiber pulse width stretching system uses a dispersive fiber to stretch the fs pulse into a ps pulse for fs lasers. The spatial pulse width compression system uses a spatial dispersive grating pair to compress the stretched and amplified ps pulse back into an fs pulse for fs lasers.

[0035] Compared with the prior art, the present invention and its preferred embodiment can achieve ultra-high frequency ultrafast laser output, ultra-high repetition frequency from Ghz to hundreds of Ghz, and can also achieve fast repetition frequency adjustment switching, and the switching frequency can reach hundreds of Khz to Mhz.

[0036] First of all, it uses AOD acousto-optic deflector, AOD acousto-optic deflector and variable frequency RF control system, collimation beam splitting optical system, focusing lens array, fiber array, fiber repetition rate multiplication system, VOA adjustable attenuation system, which can simultaneously achieve high repetition rate pulse output from GHz to 100 GHz and adjustable frequency, and achieve the average power / pulse energy to remain unchanged at different repetition frequencies. AOD acousto-optic deflector and variable frequency RF control system can achieve fast repetition rate switching from 100 Khz to MHz.

[0037] Secondly, it cooperates with the combiner, AO-picker frequency selector, fiber pulse width stretching system, gain fiber amplification system, multi-stage solid amplification system, spatial pulse width compression system, waveform modulator (electro-optic / acousto-optic), and output spot shaping system. It can achieve high repetition frequency pulse amplification from Ghz to 100 Ghz, obtain picosecond / femtosecond laser output with hundreds of watts of average power, and can achieve single pulses with nanosecond to millisecond width to ultra-high frequency picosecond / femtosecond pulse train output with Mhz frequency of 100 Ghz as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the basic structure of the preferred embodiment of the present invention;

[0039] Figure 2 Schematic diagram of the structure and working principle of the 8-fold and 32-fold repetition rate multipliers of the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the features and advantages of this patent more obvious and easy to understand, the following embodiments are specifically described in detail as follows:

[0041] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0042] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0043] The basic structure diagram of the present invention is as follows Figure 1 As shown in the figure, a proposed ultra-high frequency ultrafast laser system with adjustable repetition frequency mainly includes:

[0044] Arranged in sequence on the optical path are: a 100-MHz repetition rate ultrafast seed source, an AOD acousto-optic deflector connected to a variable-frequency RF control system, a collimating beam splitting optical system, a focusing lens array, an optical fiber array, an optical fiber repetition rate multiplication system, a VOA adjustable attenuation system, a Combiner beam combiner, an AO-picker frequency selector, an optical fiber pulse width stretching system, a gain optical fiber amplification system, a multi-stage solid-state amplification system, a spatial pulse width compression system, an electro-optic / acousto-optic waveform modulator, and an output light spot shaping system.

[0045] The fiber pulse width stretching system and the spatial pulse width compression system are not necessary for picosecond pulses, and can be retained or not according to the actual pulse width and the nonlinearity of the amplification system.

[0046] Specifically, the ultrafast seed source with a repetition rate of 100 MHz uses the mature SESAM passive mode locking technology to achieve picosecond / femtosecond pulse output with a repetition rate of 100 MHz;

[0047] After being connected to the output of the fiber collimator, it is incident into the AOD acousto-optic deflector, and the beam waist is located at the AOD output end. The AOD provides signals of different RF frequencies through a variable frequency RF control system to achieve different diffraction angles, corresponding to different output angles of the AOD.

[0048] The AOD acousto-optic deflector is connected to a collimating beam splitting optical system, and its front effective focal length is considered to be d, and the distance between it and the AOD is set to d.

[0049] The collimating beam splitting optical system is followed by a focusing lens array, which focuses and couples the light at different angles after the AOD into the fiber array. The focusing lens array and the fiber array contain n channels, which can be set according to actual needs, and the minimum spacing can reach 125um.

[0050] The fiber array is connected to a fiber repetition rate multiplication system, where each fiber is connected to a fiber repetition rate multiplier, which can achieve 2 times, 4 times, 8 times, 16 times...2 n The repetition frequency is increased by times, and a repetition frequency pulse of hundreds of GHz can be achieved. The ultrafast seed source signal can be controlled to enter the optical fiber repetition frequency multiplier of different channels by controlling the RF frequency of the AOD system, so as to realize fast adjustment and switching between different repetition pulses. The adjustment switching frequency can reach a frequency of hundreds of Khz to Mhz.

[0051] After the optical fiber repetition rate multiplication system, the optical fiber is connected to the VOA adjustable attenuation system, and the insertion loss of each VOA is adjusted according to the laser power output by each optical fiber repetition rate multiplier to achieve the same average output power of each channel or obtain the desired power output.

[0052] The VOA adjustable attenuation system is then fused with a combiner to couple the signal lights into an optical fiber, and then fused with an AO-picker to modulate the ultra-high frequency signals. This can achieve single pulses with a width of nanoseconds to milliseconds to ultra-high frequency picosecond / femtosecond pulse train outputs with a frequency of hundreds of GHz.

[0053] The Combiner is followed by a fiber pulse width stretching system, which uses dispersion delay to stretch the pulse width for subsequent amplification. The gain fiber amplification system and the multi-stage solid-state amplification system use gain fiber and solid gain medium, respectively, to amplify the signal light, which can amplify nJ / uJ signal light to hundreds of uJ / mJ single pulse energy. The spatial pulse width compression system uses a dispersion-compensated spatial grating system to compress the stretched pulse back to picosecond / femtosecond pulses. The waveform modulator (electro-optic / acousto-optic) realizes the switching and modulation functions of the output amplified ultrafast laser, and the output spot shaping system shapes the output spot to the required spot size and divergence angle.

[0054] Furthermore, as a preferred solution, the 100 MHz repetition rate ultrafast seed source can use a SESAM passive mode-locked ultrafast seed source, 1064nm, 200Mhz repetition rate, 1nJ single pulse energy, 10ps pulse width output parameters, single-mode polarization-maintaining fiber collimation isolator output. Other parameters of ps or fs seed sources can also be selected.

[0055] The fiber repetition rate multiplication system can adopt a 7-channel system to achieve 8 times, 16 times, 32 times, 64 times, 128 times, 256 times, and 512 times repetition frequency increases respectively. Corresponding to a 200Mhz seed source, it can achieve 1.6Ghz, 3.2Ghz, 6.4Ghz, 12.8Ghz, 25.6Ghz, 51.2Ghz, and 102.4Ghz high repetition rate outputs respectively.

[0056] The AOD acousto-optic deflector can use a frequency conversion of 72.5Mhz-107.5Mhz to achieve an angle change of 3.2 degrees. There are seven channels, and the deflection angle interval of each channel is 0.53 degrees.

[0057] The focusing lens array adopts a 7-channel microlens array, the optical fiber array adopts a 7-channel optical fiber array, and the optical fiber adopts a single-mode or quasi-single-mode polarization-maintaining or non-polarization-maintaining optical fiber.

[0058] The VOA adjustable attenuation system uses 7-channel optical fiber electric attenuators to electronically control the loss of each channel and can be connected to the feedback system for dynamic control, so that the average output power or single pulse energy remains unchanged when the repetition frequency is adjusted and switched.

[0059] The Combiner uses a 7-in-1 combiner to couple 7 optical signals into the same optical fiber.

[0060] AO-picker frequency selector, using 200Mhz frequency AO-picker can generate ns to ms width pulse train within 50Mhz modulation frequency.

[0061] Fiber pulse width stretching system, for fs laser, can use dispersive fiber to stretch fs pulse into ps pulse.

[0062] The gain fiber amplification system selects Yb-doped gain fiber and 975nm pump source to pre-amplify the seed signal laser to achieve 10-20 times gain amplification.

[0063] Multi-stage solid-state amplification system, selects Nd:YVO4 / Nd:YAG as gain medium, 878nm pump source, multi-stage gain amplification, and achieves 100-1000 times gain amplification.

[0064] Waveform modulator (electro-optic / acousto-optic), using 80Mhz, AOQS acousto-optic modulator, switches and modulates the output laser.

[0065] Each repetition frequency multiplier in the fiber repetition frequency multiplication system uses the principle of optical path phase delay to split a beam of light with a repetition frequency of f into two paths. By controlling the optical path difference between the two paths, one path is delayed by half a repetition frequency cycle compared to the other path, and then the beams are combined to achieve a 2f repetition frequency output. Through multiple splitting, delaying, and combining, 4f, 8f...2 n Repetition frequency output.

[0066] This example is an optical fiber structure, so the optical path difference is the difference in length between the two optical fibers.

[0067] Taking the 8-fold and 32-fold repetition frequency multipliers as examples, their structures are as follows: Figure 2 As shown:

[0068] In the 8X repetition rate multiplier, the base frequency is 200Mhz, the time period is t=5ns, the half period is 2.5ns, and the fiber refractive index n=1.45, so 4ΔL=c*t / n=0.517m, 2ΔL=0.258m, ΔL=0.129m.

[0069] In the 32X repetition rate multiplier, the base frequency is 200Mhz, the time period is t=5ns, the half period is 2.5ns, and the fiber refractive index n=1.45, so 16ΔL=c*t / n=0.517m, 8ΔL=0.258m, 4ΔL=0.129m, 2ΔL=0.064m, ΔL=0.032m.

[0070] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

[0071] This patent is not limited to the above-mentioned best implementation mode. Anyone can derive other forms of ultra-high frequency ultrafast laser systems with adjustable repetition frequency under the inspiration of this patent. All equivalent changes and modifications made according to the scope of the patent application of the present invention should be covered by this patent.

Claims

1. An ultra-high frequency ultrafast laser system with adjustable repetition frequency, characterized in that: include: Arranged in sequence on the optical path are: an ultrafast seed source with a repetition rate of 100 MHz, an AOD acousto-optic deflector connected to a frequency-converting RF control system, a collimating beam splitting optical system, a focusing lens array, an optical fiber array, an optical fiber repetition rate multiplication system, a VOA adjustable attenuation system, a Combiner beam combiner, an AO-picker frequency selector, a gain optical fiber amplification system, a multi-stage solid-state amplification system, an electro-optic or acousto-optic waveform modulator, and an output light spot shaping system.

2. The ultra-high frequency ultrafast laser system with adjustable repetition frequency according to claim 1, characterized in that: An optical fiber pulse width stretching system is arranged between the AO-picker frequency selector and the gain optical fiber amplification system; and a spatial pulse width compression system is arranged between the multi-stage solid-state amplification system and the electro-optic or acousto-optic waveform modulator.

3. The ultra-high frequency ultrafast laser system with adjustable repetition frequency according to claim 1, characterized in that: The 100 MHz repetition rate ultrafast seed source is connected to the output of the optical fiber collimator and then incident on the AOD acousto-optic deflector. The beam waist is located at the output end of the AOD acousto-optic deflector. The AOD acousto-optic deflector provides signals of different radio frequency frequencies through a variable frequency radio frequency control system to achieve different diffraction angles, corresponding to different output angles of the AOD acousto-optic deflector. The AOD acousto-optic deflector is connected to a collimating beam splitting optical system, and the distance between the AOD acousto-optic deflector and the AOD acousto-optic deflector is set to its front effective focal length d; The collimating beam splitting optical system is connected to a focusing lens array to focus and couple the light at different angles after the AOD acousto-optic deflector to the optical fiber array, and the focusing lens array and the optical fiber array include n channels; The optical fiber array is connected to an optical fiber repetition rate multiplication system, wherein each optical fiber is connected to an optical fiber repetition rate multiplier, and the radio frequency frequency of the AOD acousto-optic deflector is controlled to control the ultrafast seed source signal of the repetition rate of 100 MHz to enter the optical fiber repetition rate multipliers of different channels, so as to realize fast adjustment and switching between different repetition pulses; The optical fiber repetition rate multiplication system is connected to the VOA adjustable attenuation system through optical fiber, and the insertion loss of each VOA is adjusted according to the laser power output by each optical fiber repetition rate multiplier, so as to achieve the same average power output of each channel or obtain the required power output; The VOA adjustable attenuation system is then fused with a combiner to couple the signal lights of each channel into an optical fiber, and then fused with an AO-picker to modulate the ultra-high frequency signals of each channel to achieve the output of ultra-high frequency picosecond / femtosecond pulse trains with a width of nanoseconds to milliseconds and a frequency of hundreds of GHz.

4. The ultra-high frequency ultrafast laser system with adjustable repetition frequency according to claim 1, characterized in that: The gain fiber amplification system and the multi-stage solid amplification system respectively use gain fiber and solid gain medium to amplify the signal light, and amplify the nJ / uJ signal light to hundreds of uJ / mJ single pulse energy; the electro-optic or acousto-optic waveform modulator is used to realize the switching and modulation functions of the output amplified ultrafast laser, and the output spot shaping system shapes the output spot to the required spot size and divergence angle.

5. The ultra-high frequency ultrafast laser system with adjustable repetition frequency according to claim 2, characterized in that: The combiner is connected to a fiber pulse width stretching system to stretch the pulse width using dispersion delay for subsequent amplification; the spatial pulse width compression system uses a dispersion compensation spatial grating system to compress the stretched pulse back into a picosecond / femtosecond pulse.

6. The ultra-high frequency ultrafast laser system with adjustable repetition frequency according to claim 1, characterized in that: The 100 MHz repetition rate ultrafast seed source adopts a SESAM passive mode-locked ultrafast seed source; The optical fiber repetition frequency multiplication system adopts a 7-channel system to achieve 8 times, 16 times, 32 times, 64 times, 128 times, 256 times, and 512 times repetition frequency increases, respectively. Corresponding to a 200Mhz seed source, it achieves 1.6Ghz, 3.2Ghz, 6.4Ghz, 12.8Ghz, 25.6Ghz, 51.2Ghz, and 102.4Ghz high repetition frequency outputs respectively; The AOD acousto-optic deflector uses a conversion frequency of 72.5Mhz-107.5Mhz to achieve an angle change in the range of 3.2 degrees; the deflection angle interval of each channel corresponding to the 7 channels is 0.53 degrees; The focusing lens array adopts a 7-channel microlens array, the optical fiber array adopts a 7-channel optical fiber array, and the optical fiber adopts a single-mode or quasi-single-mode polarization-maintaining or non-polarization-maintaining optical fiber; the VOA adjustable attenuation system adopts a 7-channel optical fiber electrically adjustable attenuator, electronically controls the loss of each channel, and performs dynamic control by accessing a feedback system, so that the average output power or single pulse energy remains unchanged when the repetition frequency is adjusted and switched; The Combiner uses a 7-in-1 combiner to couple 7 optical signals into the same optical fiber.

7. The ultra-high frequency ultrafast laser system with adjustable repetition frequency according to claim 1, characterized in that: The AO-picker frequency selector adopts a 200Mhz frequency AO-picker frequency selector to generate a ns to ms width pulse train within a 50Mhz modulation frequency; The gain fiber amplification system uses Yb-doped gain fiber and 975nm / 915nm pump source to pre-amplify the seed signal laser to achieve 10-20 times gain amplification; The multi-stage solid-state amplification system uses Nd:YVO4 / Nd:YAG as a gain medium, 878nm / 808nm pump source, and multi-stage gain amplification to achieve 100-1000 times gain amplification; The waveform modulator uses an 80Mhz AOQS acousto-optic modulator to switch and modulate the output laser.

8. The ultra-high frequency ultrafast laser system with adjustable repetition frequency according to claim 1, characterized in that: Each repetition frequency multiplier in the optical fiber repetition frequency multiplication system uses the principle of optical path phase delay to split a beam of light with a repetition frequency of f into two paths, and by controlling the optical path difference between the two paths, one path is delayed by half a repetition frequency cycle compared with the other path, and then the beams are combined to achieve a 2f repetition frequency output; through multiple beam splitting, delaying, and beam combining, 2f, 4f, 8f...2 are achieved respectively. n Repetitive frequency output to achieve 100 GHz repetition frequency pulse output.

9. The ultra-high frequency ultrafast laser system with adjustable repetition frequency according to claim 2, characterized in that: The fiber pulse width stretching system, for femtosecond laser, uses dispersive fiber to stretch femtosecond pulses into picosecond pulses; the spatial pulse width compression system, for femtosecond laser, uses spatial dispersive grating pairs to compress the stretched and amplified picosecond pulses back into femtosecond pulses.

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