System and method for compensating high order dispersion by cooperative regulation of broadening and compression

Abstract

The application belongs to the field of laser emitting devices, and provides a system and method for compensating high-order dispersion through cooperative adjustment of stretching and compression, calculating second-order dispersion and third-order dispersion introduced by a pulse amplifier; adjusting the introduced third-order dispersion by changing the grating incident angle in a pulse stretcher, so that the third-order dispersion is offset with the total third-order dispersion of the system; calculating the second-order dispersion value required to be provided by the pulse compressor according to the second-order dispersion change generated after the angle adjustment of the pulse stretcher, and accurately compensating by adjusting the effective distance of the grating pair; feeding back the third-order dispersion of the pulse compressor after adjustment to correct the angle of the pulse stretcher again, and repeating the above steps until the total second-order dispersion and third-order dispersion of the system tend to be zero, so as to realize near transform limit compression. The application adjusts the grating incident angle of the stretcher and the effective distance of the grating of the compressor, so that the second-order dispersion and third-order dispersion in the ultrafast laser system are simultaneously compensated, and near transform limit pulse output is obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of laser emitting devices, and particularly relates to a system and method for compensating high-order dispersion through coordinated adjustment of pulse stretching and compression. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] Femtosecond lasers have been widely used in precision machining, biological imaging, spectral analysis and other fields. One of the core indicators for measuring the performance of a laser system is the energy and pulse width of a laser pulse. Generally, the average power of a femtosecond laser oscillator is only in the order of milliwatts, the single-pulse energy is low, and the peak power is limited, which is difficult to meet the demand of high-energy applications. Therefore, it is necessary to regenerate and amplify the femtosecond pulse. However, due to the extremely short time width of the femtosecond pulse, if it is directly amplified, its high peak power is likely to exceed the damage threshold of the gain medium and other optical elements in the system, resulting in nonlinear effects and even device damage.

[0004] To solve the above problems, the "Chirped Pulse Amplification (CPA)" technology is usually introduced. This technology uses a pulse stretcher to lengthen the femtosecond pulse to picoseconds or longer, thereby reducing the peak power, and then uses an amplifier to increase the energy, and finally uses a compressor to restore the short pulse output. Although this method effectively avoids nonlinear damage, the second-order dispersion (GDD) and third-order dispersion (TOD) are inevitably introduced into the system.

[0005] The dispersion introduced in the system mainly comes from two aspects: one is the material dispersion of the gain medium, which causes the difference in the propagation speed of different wavelengths of light, resulting in the delay of frequency components; the other is the dispersion characteristics of various optical devices (such as lenses, mirrors, etc.) in the system. The second-order dispersion (GDD) is adjustable and controllable to some extent, and is usually compensated by adjusting the grating pitch in the compressor. However, the third-order dispersion (TOD) belongs to the high-order term of the dispersion rate, and the pulse distortion caused by it, such as tailing, ringing, sub-pulse and other phenomena, seriously affects the pulse quality and time resolution, and there is currently a lack of an effective and simple compensation method. SUMMARY

[0006] To solve the above problems, the present application proposes a system and method for compensating high-order dispersion through coordinated adjustment of pulse stretching and compression. By adjusting the grating incident angle of the stretcher and the effective distance of the grating of the compressor, the present application realizes the synchronous compensation of the second-order and third-order dispersion in the ultrafast laser system, thereby obtaining near-transform-limited pulse output.

[0007] According to some embodiments, the present application adopts the following technical solutions:

[0008] A system for compensating high-order dispersion by cooperative adjustment of pulse expansion and compression, comprising:

[0009] A pulse oscillator for generating seed pulses in the order of femtosecond or picosecond pulses;

[0010] A pulse expander with a grating structure, which changes the dispersion by adjusting the grating incident angle and the effective distance of the grating pair, provides positive second-order dispersion, and realizes the expansion of the seed pulses generated by the pulse oscillator;

[0011] A pulse amplifier for amplifying the expanded seed pulses, which will introduce some redundant second-order dispersion and third-order dispersion in the process of amplification;

[0012] A pulse compressor with a grating structure, which changes the dispersion by adjusting the grating incident angle and the effective distance of the grating pair, provides negative second-order dispersion to compress the amplified seed pulses;

[0013] A cooperative compensation module for calculating the second-order dispersion and third-order dispersion introduced by the pulse amplifier; by changing the grating incident angle in the pulse expander, adjusting the introduced third-order dispersion to cancel it with the total third-order dispersion of the system; according to the change of the second-order dispersion generated by the pulse expander after adjusting the angle, calculating the second-order dispersion value required to be provided by the pulse compressor, and accurately compensating by adjusting the effective distance of the grating pair; according to the feedback of the adjusted third-order dispersion of the pulse compressor, revising the angle of the pulse expander again, repeating the above steps until the total second-order dispersion and third-order dispersion of the system tend to zero, realizing near transform-limited compression.

[0014] As an optional implementation, the gratings in the grating structure are transmissive or reflective gratings, and the ruling density of the gratings ranges from [600 lines / mm, 1800 lines / mm], i.e., [600 lines per millimeter, 1800 lines per millimeter].

[0015] As a further implementation, the grating incident light and the diffracted light of the grating satisfy the grating equation.

[0016] When the incident angle and the diffraction angle are equal and satisfy the condition of Littrow angle, the maximum diffraction efficiency is obtained.

[0017] As a further implementation, the range of the grating incident light is [36°, 70°].

[0018] As an optional implementation, the effective distance of the grating pair can be adjusted in the range of [0.3 m, 1.0 m].

[0019] As an alternative embodiment, the pulse stretcher is a double-grating structure, comprising a first diffraction grating, a 4f system, a second diffraction grating and a mirror arranged in sequence according to the light path, the first diffraction grating is used to spatially spread the incident light and control the dispersion by adjusting the incident angle thereof;

[0020] The 4f system is composed of two equal focal length lenses, forming a 1:1 imaging structure;

[0021] The second diffraction grating is used to collimate the light path back;

[0022] The mirror is used to turn back the light path.

[0023] As an alternative embodiment, the pulse stretcher is a single-grating structure, and the light path thereof sequentially comprises a first diffraction grating, a concave mirror, a convex mirror and a roof mirror;

[0024] The concave mirror focuses the diffracted light to the convex mirror;

[0025] The convex mirror and the concave mirror are placed concentrically to form a telescope system, and the light is reflected again;

[0026] The roof mirror is used to turn back the light path, so that the light can follow a predetermined path to realize four-pass or eight-pass folded optical path.

[0027] As an alternative embodiment, the pulse stretcher is a double-grating structure, comprising a first diffraction grating, a second diffraction grating and a mirror arranged in sequence according to the light path, the two diffraction gratings are arranged in parallel, and the system dispersion is adjusted by changing the grating pair distance;

[0028] The mirror is used for light path turn back.

[0029] As an alternative embodiment, the pulse stretcher is a single-grating structure, comprising a first diffraction grating, a mirror and a roof mirror;

[0030] The mirror turns back the light beam to the effective area of the first diffraction grating;

[0031] The roof mirror is used to adjust the light path, and the light beam can be turned back multiple times.

[0032] As an alternative embodiment, when the pulse stretcher is a single-grating structure, the process of adjusting the effective distance of the grating pair to accurately compensate is replaced by adjusting the effective distance between the grating and the mirror to accurately compensate.

[0033] The working method of the above-mentioned stretcher-compressor collaborative adjustment and compensation system for high-order dispersion comprises the following steps:

[0034] The pulse oscillator generates seed pulses in the order of femtosecond and picosecond pulses;

[0035] The pulse stretcher changes dispersion by adjusting grating incident angle and grating effective distance, provides positive second-order dispersion, and realizes stretching of the seed pulse generated by the pulse oscillator;

[0036] The pulse amplifier amplifies the stretched seed pulse, and in the amplification process, part of the second-order dispersion and third-order dispersion is introduced;

[0037] The pulse compressor changes dispersion by adjusting grating incident angle and grating effective distance, provides negative second-order dispersion to compress the amplified seed pulse;

[0038] The cooperative regulation compensation module calculates the second-order dispersion and third-order dispersion introduced by the pulse amplifier; the third-order dispersion introduced is adjusted by changing the grating incident angle in the pulse stretcher, so that the third-order dispersion is cancelled with the total third-order dispersion of the system; the second-order dispersion value required to be provided by the pulse compressor is calculated according to the change of the second-order dispersion generated after the angle adjustment of the pulse stretcher, and the effective distance of the grating pair is adjusted to accurately compensate; the angle of the pulse stretcher is again corrected according to the third-order dispersion feedback after the adjustment of the pulse compressor, and the above steps are repeated until the total second-order dispersion and third-order dispersion of the system tend to be zero, and near transform limit compression is realized.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] The present application does not need additional optical elements, has simple structure, high adjustment freedom, realizes synchronous compensation of the second-order dispersion and third-order dispersion in the ultrafast laser system by adjusting the grating incident angle of the stretcher and the grating effective distance of the compressor, so that near transform limit pulse output is obtained, the present application can effectively compensate or minimize the influence of the third-order dispersion in the amplification system, and is beneficial to further improving the quality and stability of the output pulse of the ultrafast laser system.

[0041] The present application has wide application range, is suitable for ultrafast laser systems with limited space or extremely high requirements on the quality of output pulses, and can realize comprehensive compensation of non-ideal dispersion of the system.

[0042] In order to make the above-mentioned purposes, characteristics and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0043] The drawings accompanying the specification of the present application serve to provide a further understanding of the present application, the schematic embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application.

[0044] Figure 1 It is a structure schematic view of a transmission type double-grating pulse stretcher of an embodiment;

[0045] Figure 2 Structure diagram of a reflective double-grating pulse stretcher according to an embodiment;

[0046] Figure 3 Structure diagram of a transmissive single-grating pulse stretcher according to an embodiment;

[0047] Figure 4 Structure diagram of a reflective single-grating pulse stretcher according to an embodiment;

[0048] Figure 5 Structure diagram of a transmissive double-grating pulse compressor according to an embodiment;

[0049] Figure 6 Structure diagram of a reflective double-grating pulse compressor according to an embodiment;

[0050] Figure 7 Structure diagram of a transmissive single-grating pulse compressor according to an embodiment;

[0051] Figure 8 Structure diagram of a reflective single-grating pulse compressor according to an embodiment;

[0052] Figure 9 Flow chart of dispersion compensation iteration according to an embodiment.

[0053] In the figure, 101 is a transmissive grating, 102 is a reflective grating, 2 is a lens with a certain focal length, two lenses can form a 4f system; 3 is a mirror; 4 is a convex mirror; 5 is a concave mirror; 6 is a plane mirror; 7 is a roof mirror. DETAILED DESCRIPTION

[0054] The application will be further described below in conjunction with the accompanying drawings and embodiments.

[0055] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0056] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should be further understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of a feature, step, operation, device, component, and / or combination thereof.

[0057] The embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0058] Embodiment one

[0059] A system for compensating high-order dispersion by means of cooperative adjustment of pulse expansion and compression, comprising:

[0060] A pulse oscillator (hereinafter referred to as oscillator) for generating seed pulses in the order of femtosecond and picosecond pulses;

[0061] A pulse expander (hereinafter referred to as expander) having a grating structure, which changes dispersion by adjusting grating incident angle and grating effective distance, provides positive second-order dispersion, and realizes expansion of the seed pulses generated by the pulse oscillator;

[0062] A pulse amplifier (hereinafter referred to as amplifier) for amplifying the expanded seed pulses, which will introduce part of the redundant second-order dispersion and third-order dispersion in the process of amplification;

[0063] A pulse compressor (hereinafter referred to as compressor) having a grating structure, which changes dispersion by adjusting grating incident angle and grating effective distance, provides negative second-order dispersion to compress the amplified seed pulses;

[0064] A cooperative adjustment compensation module, as shown in Figure 9 which is used for calculating the second-order dispersion and third-order dispersion introduced by the pulse amplifier; by changing the grating incident angle in the pulse expander, the introduced third-order dispersion is adjusted to be offset by the total third-order dispersion of the system; according to the change of the second-order dispersion generated after the angle adjustment of the pulse expander, the second-order dispersion value required to be provided by the pulse compressor is calculated, and the effective distance of the grating pair is adjusted to accurately compensate; according to the feedback of the adjusted third-order dispersion of the pulse compressor, the angle of the pulse expander is modified again, and the above steps are repeated until the total second-order dispersion and third-order dispersion of the system tend to be zero, and near transform-limited compression is realized.

[0065] The grating parameter design described in the present application can be adapted to the near-infrared waveband (such as Yb laser center wavelength 1020-1080nm), but those skilled in the art should understand that the method is also applicable to other working wavebands (such as 800nm, 1550nm, etc.) by adjusting the grating ruling density and incident angle to achieve similar dispersion adjustment.

[0066] The grating used in the present application can be a transmissive or reflective grating, and the ruling density range is 600-1800 lines / mm, which is selected according to the required dispersion value, incident angle matching and laser working wavelength.

[0067] If it is a reflective grating, it works near the Littrow angle; when the incident angle deviates from the Littrow angle too much, the diffraction efficiency is reduced.

[0068] The incident and diffracted light of different types of gratings satisfy the grating equation:

[0069] (1)

[0070] In the formula, m is the diffraction order of the grating. Λ is the wavelength, and Λ is the grating period. The angle of incidence of the beam. The angle is the beam diffraction angle.

[0071] Maximum diffraction efficiency is achieved when the incident angle and the diffraction angle are equal and the Littorau angle condition is satisfied. At this point, the optimal angle of incidence :

[0072] (2)

[0073] By properly configuring the grating parameters, the desired GDD and TOD can be obtained. The system's phase delay can be expressed using Taylor expansion:

[0074] (3)

[0075] The above formula, represent right At angular frequency The nth derivative at point n. For the center frequency, Group delay represents the time it takes for light of that frequency to travel through the system; Second-order dispersion will broaden the pulse. and Third-order and fourth-order dispersion will cause pulse distortion.

[0076] Second-order dispersion GDD and third-order dispersion TOD can be expressed as follows:

[0077] (4)

[0078] (5)

[0079] Where c is the speed of light in a vacuum, and Lg is the perpendicular distance between the grating pairs.

[0080] The reflector 3, lens, and other optical components used in this invention should have a high-reflectivity or high-transmittance coating that matches the laser wavelength used, such as HR@1020-1080nm or a broadband anti-reflection coating. The type of coating is not limited; appropriate coating schemes can be selected according to different laser center wavelengths.

[0081] The incidence angle of the grating in the stretcher or the compressor in the present application should be calculated according to the grating equation, and should be set in combination with the dispersion adjustment requirement. Preferably, the incidence angle is 38.9° to meet the Littrow condition or an angle near the same (such as 36°-40°), so as to realize high diffraction efficiency and dispersion adjustment capability. The incidence angle under different wavelengths and ruling densities can be adjusted by a person skilled in the art as required.

[0082] The mirror used to turn back the light path in the present application can be a roof mirror 7, or can be a common plane mirror 6, which is selected according to the specific application requirement.

[0083] The effective distance between the grating pairs in the stretcher and the compressor in the present application is adjustable, and ranges from 0.3 m to 1.0 m. This parameter directly determines the dispersion amount, and adjusting the length can effectively compensate for the GDD introduced in the amplifier.

[0084] The structure form of the stretcher and the compressor in the present application is not limited, and can be a double-grating+4f system structure, a single-grating+mirror structure, etc. The above structures can be flexibly selected according to the space layout, dispersion requirement and integration, and all can realize high-order dispersion compensation through the adjustment method described in the present application.

[0085] As shown in Figure 1 and Figure 2 , in some embodiments, the stretcher is a double-grating structure, which includes a first diffraction grating, a 4f system, a second diffraction grating and a mirror arranged in sequence according to the light path.

[0086] The first diffraction grating is used to spatially spread the incident light and control the dispersion by adjusting the incidence angle thereof;

[0087] The 4f system is composed of two equal- focal-length lenses to form a 1:1 imaging structure;

[0088] The second diffraction grating is used to collimate the light path back;

[0089] The mirror is used to turn back the light path.

[0090] Of course, according to the type of the grating, which is a transmissive grating 101 or a reflective grating 102, the position of the mirror 3 is adaptively adjusted.

[0091] As shown in Figure 3 and Figure 4 , in some embodiments, the stretcher can also be a single-grating structure, and the light path thereof sequentially includes a first diffraction grating, a concave mirror 5, a convex mirror 4 and a roof mirror 7.

[0092] The concave mirror 5 focuses the diffracted light to a convex mirror; the convex mirror 4 is placed coaxially with the concave mirror to form a telescopic system, and the light is reflected again.

[0093] As shown in Figure 5 and Figure 6 In some embodiments, the compressor is a double-grating structure, which includes a first diffraction grating, a second diffraction grating and a mirror arranged in sequence according to the light path. The two gratings are arranged in parallel, and the system dispersion is adjusted by changing the grating pair distance; the mirror is used for light path return.

[0094] As shown in Figure 7 and Figure 8 In some embodiments, the compressor can also be a single-grating structure, which includes a first diffraction grating, a mirror and a roof mirror 7.

[0095] The mirror returns the light beam to the effective area of the grating;

[0096] The roof mirror 7 is used to adjust the light path, and can return the light beam multiple times.

[0097] Similarly, according to the type of grating, which is a transmissive grating 101 or a reflective grating 102, the positions of the mirror 3 and the roof mirror 7 are adaptively adjusted.

[0098] The present application is applicable to various CPA architecture ultrafast laser systems, including but not limited to: femtosecond oscillator, stretcher, regenerative amplifier and compressor structure system. The method can also be applied to OPCPA, picosecond system, nonlinear amplification system and other occasions.

[0099] The present application is applicable to ultra-short laser pulse systems with pulse width between 30 fs and 1000 fs, and can obtain pulses close to the transform limit after compression. The average power of the system output pulse can cover the range from mW to hundreds of watts, and the peak power can reach TW level.

[0100] In this embodiment, the grating parameters are as follows: the grating line period is 833 nm, and the corresponding line number is 1200 lines / mm. The center wavelength of the incident pulse is 1048 nm. According to the grating equation, when the incident angle is 38.96°, the grating has the highest diffraction efficiency. The effective propagation distance of the grating in the stretcher is set to 0.4 m.

[0101] In an ideal case, if the amplifier does not introduce additional dispersion (GDD = 0, TOD = 0), the compressor structure can be set to be completely symmetrical with the stretcher, i.e. the effective distance of the compressor gratings is also 0.4 m. In this configuration, the dispersion value provided by the compressor will be exactly equal to and opposite to the dispersion amount of the stretcher, thereby achieving perfect compensation for the dispersion introduced by the stretcher, and compressing the pulse to the transform limit. At this time, the dispersion parameters provided by the stretcher and the compressor respectively are: the absolute value of the dispersion is |GDD| = 49.88 x 10 5 fs 2 , |TOD| = 96 x 10 5 fs 3 .

[0102] However, in an actual system, the amplifier part inevitably introduces a certain amount of high-order dispersion. In the present embodiment, the dispersion parameters of the amplifier are GDD = 2.3 x 10 5 fs 2 , TOD = 7 x 10 5 fs 3 . If the high-order dispersion existing in the system cannot be completely eliminated, it will cause serious distortion of the pulse in the time domain. The pedestal of low intensity is generated on both sides of the pulse, which reduces the peak power of the pulse and also affects the efficiency of subsequent other nonlinear optical processes.

[0103] In order to achieve the recompression of the pulse, the incident angle of the pulse stretcher and the effective distance of the gratings of the compressor need to be adjusted in coordination, and the system dispersion is finally completely compensated.

[0104] Specifically, in the present embodiment, first, the grating incident angle of the stretcher is adjusted to 38°, sacrificing a part of the diffraction efficiency within an acceptable range, so as to make the third-order dispersion (TOD ≈ -103 x 10 5 fs 3 ) provided by the stretcher offset the TOD introduced by other optical units of the system, and achieve preliminary compensation for the third-order dispersion. Since the change of the incident angle will also affect the GDD (here, 52.017 x 10 5 fs 2 ) provided by the stretcher, the effective propagation distance between the gratings of the compressor needs to be adjusted synchronously, so as to make the GDD (here, -54.317 x 10 5 fs 2 ) provided by the compressor offset the sum of the GDD of the stretcher and the amplifier.

[0105] However, the change of the effective distance of the compressor will also affect the TOD value of its output (e.g. after adjustment, +105 x 10 5 fs 3), at this time, the incident angle of stretcher needs to be adjusted again to maintain the balance of the overall TOD compensation of the system. The incident angle of stretcher and the effective propagation distance of compressor grating are adjusted repeatedly until the overall GDD and TOD of the system are compensated completely, and the output pulse is compressed to the pulse width close to the transform limit.

[0106] The following calculation results are specific adjustment examples of an optimized configuration (as shown in Table 1, in Table 1, the unit of GDD is × 10 5 fs 2 , and the unit of TOD is × 10 5 fs 3 ): when the incident angle of stretcher grating is 35.9° and the effective propagation distance of compressor grating is 480.15 mm, the overall GDD and TOD of the system are completely compensated, and the output pulse can be compressed to the shortest.

[0107] Table 1: System configuration parameter table

[0108]

[0109] Embodiment Two

[0110] The working method of the stretcher-compressor collaborative adjustment and compensation system for high-order dispersion provided in Embodiment One includes the following steps:

[0111] The pulse oscillator generates seed pulses in the order of femtosecond and picosecond pulses;

[0112] The pulse stretcher changes the dispersion by adjusting the grating incident angle and the effective distance of grating, provides positive second-order dispersion, and realizes the stretching of the seed pulses generated by the pulse oscillator;

[0113] The pulse amplifier amplifies the stretched seed pulses, and in the process of amplification, part of the redundant second-order dispersion and third-order dispersion is introduced;

[0114] The pulse compressor changes the dispersion by adjusting the grating incident angle and the effective distance of grating, provides negative second-order dispersion to compress the amplified seed pulses;

[0115] The collaborative adjustment and compensation module calculates the second-order dispersion and third-order dispersion introduced by the pulse amplifier; by changing the grating incident angle in the pulse stretcher, the introduced third-order dispersion is adjusted to be offset with the overall third-order dispersion of the system; according to the change of the second-order dispersion generated by the pulse stretcher after the angle adjustment, the second-order dispersion value required to be provided by the pulse compressor is calculated, and the effective distance of the grating pair is adjusted to accurately compensate; according to the third-order dispersion feedback of the pulse compressor after adjustment, the angle of the pulse stretcher is corrected again, and the above steps are repeated until the overall second-order dispersion and third-order dispersion of the system tend to zero, and near transform limit compression is realized.

[0116] In the embodiment, a stretcher adjustment mechanism is proposed: by changing the grating incident angle, adjust the third-order dispersion TOD introduced by the stretcher to offset the total TOD of the system;

[0117] Compressor compensation mechanism: according to the GDD change generated after the angle adjustment of the stretcher, calculate the GDD value required to be provided by the compressor, and accurately compensate by adjusting the effective distance of its grating pair;

[0118] Closed-loop compensation iteration method: since TOD and GDD are coupled with each other, the total dispersion of the system is recalculated after each adjustment, and through multiple rounds of iteration calculation, the total GDD and TOD of the system are finally close to zero, realizing near-transform limit compression.

[0119] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present application without creative labor shall be included in the protection scope of the present application.

Claims

1. A system for compensating for high order dispersion by simultaneous adjustment of broadening and compression, characterized in that, include: Pulse oscillator, used to generate seed pulses in the femtosecond and picosecond pulse range; A pulse stretcher with a grating structure changes the dispersion by adjusting the incident angle and effective distance of the grating, providing positive second-order dispersion to stretch the seed pulse generated by the pulse oscillator; A pulse amplifier is used to amplify the broadened seed pulse. During the amplification process, some redundant second-order and third-order dispersion will be introduced. A pulse compressor with a grating structure changes the dispersion by adjusting the grating incident angle and the effective distance of the grating, providing negative second-order dispersion to compress the amplified seed pulse; The coordinated adjustment and compensation module is used to calculate the second-order and third-order dispersion introduced by the pulse amplifier; by changing the incident angle of the grating in the pulse stretcher, the introduced third-order dispersion is adjusted to cancel out the total third-order dispersion of the system; based on the second-order dispersion change caused by the adjustment of the pulse stretcher angle, the required second-order dispersion value of the pulse compressor is calculated, and the effective distance of its grating pair is adjusted for precise compensation; based on the third-order dispersion feedback after the adjustment of the pulse compressor, the pulse stretcher angle is corrected again, and the above steps are repeated until the total second-order and third-order dispersion of the system approaches zero, achieving near-transform limit compression; The grating in the grating structure is a transmission grating or a reflection grating, and the incident light and diffracted light of the grating satisfy the grating equation; The maximum diffraction efficiency is achieved when the incident angle and the diffraction angle are equal and the Littorau angle condition is met. The effective distance of the grating pair is adjustable within the range of [0.3 m, 1.0 m].

2. The system for compensating high order dispersion by cooperative adjustment of broadening and compression according to claim 1, characterized in that, The grating has a line density range of [600 line pairs / mm, 1800 line pairs / mm]; The range of incident light from the grating is [36°, 70°].

3. The system for compensating high order dispersion by cooperative adjustment of broadening and compression according to claim 1, characterized in that, The pulse stretcher is a dual-grating structure, including a first diffraction grating, a 4f system, a second diffraction grating, and a mirror arranged in the order of the optical path. The first diffraction grating is used to expand the incident light space and control the dispersion by adjusting its incident angle. The 4f system consists of two equal focal length lenses, forming a 1:1 imaging structure; The second diffraction grating is used to collimate the optical path back; The reflector is used to refract the light path.

4. The system for compensating high order dispersion by cooperative adjustment of broadening and compressing according to claim 1, characterized in that, The pulse stretcher is a single-grating structure, and its optical path sequentially includes a first diffraction grating, a concave mirror, a convex mirror and a roof mirror. The concave mirror focuses the diffracted light onto the convex mirror; The convex mirror and the concave mirror are placed concentrically to form a telescope system, which reflects the light again. The ridge reflector is used to fold back the optical path, enabling the light to follow a predetermined path and achieve four-way or eight-way folded optical path.

5. The system for compensating high order dispersion by cooperative adjustment of broadening and compressing according to claim 1, characterized in that, The pulse compressor has a dual-grating structure, including a first diffraction grating, a second diffraction grating, and a mirror placed in the optical path sequence. The two diffraction gratings are arranged in parallel, and the system dispersion is adjusted by changing the distance between the gratings. Reflectors are used to reflect light back.

6. The system for compensating high order dispersion by simultaneous adjustment of broadening and compressing according to claim 1, wherein, The pulse compressor is a single-grating structure, including a first diffraction grating, a mirror, and a roof mirror; The reflector refracts the light beam back into the effective region of the first diffraction grating; The roof reflector is used to adjust the optical path and can reflect the light beam multiple times.

7. A method of operating a system for compensating for high order dispersion based on the cooperative regulation of broadening and compression according to any one of claims 1 to 6, characterized in that, Includes the following steps: The pulse oscillator generates seed pulses on the order of femtosecond and picosecond pulses; The pulse stretcher changes the dispersion by adjusting the grating incident angle and the grating effective distance, provides positive second-order dispersion, and realizes the stretching of the seed pulse generated by the pulse oscillator; The pulse amplifier amplifies the stretched seed pulse, and in the amplification process, part of the redundant second-order dispersion and third-order dispersion is introduced; The pulse compressor changes the dispersion by adjusting the grating incident angle and the grating effective distance, provides negative second-order dispersion, and compresses the amplified seed pulse; The cooperative regulation compensation module calculates the second-order dispersion and third-order dispersion introduced by the pulse amplifier; the third-order dispersion introduced is adjusted by changing the grating incident angle in the pulse stretcher, so that it is offset with the total third-order dispersion of the system; the second-order dispersion value required to be provided by the pulse compressor is calculated according to the change of the second-order dispersion generated after the angle adjustment of the pulse stretcher, and the effective distance of the grating pair is adjusted to accurately compensate; the angle of the pulse stretcher is corrected again according to the feedback of the third-order dispersion adjusted by the pulse compressor, and the above steps are repeated until the total second-order dispersion and third-order dispersion of the system tend to zero, and the near transform limit compression is realized.

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