End face color dispersion compensation pulse compression device and method based on batten medium

Abstract

The invention discloses an end face color dispersion compensation pulse compression device and method based on a batten medium, and relates to the technical field of ultrafast lasers. The device comprises an ultra-short pulse laser light source, ultra-short pulses emitted by the ultra-short pulse laser light source sequentially pass through a spherical lens and a cylindrical lens to achieve beam shaping and then are transmitted to a 45-degree reflector plated with a dispersion compensation film layer sequentially through a first reflector plated with a high-reflection film and a second reflector plated with a high-reflection film. The reflected light beam is introduced into a film-coated fused quartz batten, and under the condition that the damage threshold value of a film layer and a medium is not exceeded, a resonant cavity-like structure formed by a first 0-degree reflector plated with a dispersion compensation film layer, a second 0-degree reflector plated with a dispersion compensation film layer and the film-coated fused quartz batten is utilized; and after the light beam passes through a film-coated fused quartz plate strip for multiple times, quasi-synchronization of spectrum broadening and pulse compression is realized. The device has the advantages of compact structure, high stability, high medium utilization rate, low cost and the like.

Description

Technical Field

[0001] This invention relates to the field of ultrafast laser technology, and in particular to an end-face dispersion compensation pulse compression device and method based on slab medium. Background Technology

[0002] High-power ultrashort pulse lasers have wide applications in scientific research, industry, and medicine. However, for Yb or Nd-doped lasers, although they can output high energy and high average power, the relatively narrow gain bandwidth of the gain medium means that the pulse width can typically only be maintained within the range of hundreds of femtoseconds to picoseconds, which is insufficient to meet the extremely high time resolution requirements of many ultrafast applications. This core contradiction makes nonlinear compression technology an inevitable choice for unlocking the full potential of Yb-doped and Nd-doped lasers, and a crucial bridge connecting the "high energy advantage" with the "ultrashort pulse requirement." Currently, common pulse compression methods mainly include: nonlinear compression technology based on slab arrays, nonlinear compression technology based on hollow-core fibers, and nonlinear compression technology based on multi-cavity systems. While using thin-film arrays for spectral broadening can effectively prevent medium damage caused by excessive nonlinear effects, this structure is limited by the relatively small nonlinear accumulation of the thin-film array, making it unsuitable for applications requiring large-span pulse compression. Furthermore, the relatively small area of ​​the medium through which the beam passes results in significant material waste. Using gas-filled hollow fiber for spectral broadening can compress high-energy pulses by at least one cycle, but the high requirements for directional stability and the need for a precise gas pressure control system to maintain stable gas concentration and pressure within the hollow core prevent large-scale mass production and limit its commercial value. Multi-cavity spectral broadening can achieve high-energy, large-span compression, but the complex cavity mirror design, optical path calibration, and precision machining of multi-cavity systems lead to high overall system design complexity and high manufacturing costs.

[0003] In addition, current traditional pulse compression techniques typically employ a sequential "broadening first, then compression" approach. This involves the laser pulse first undergoing spectral broadening through a nonlinear medium, followed by compression using a separate dispersion compensation element. This approach suffers from problems such as large system size, complex structure, low coupling efficiency, and poor stability. Although some schemes attempt dispersion management within the laser resonant cavity, the nonlinear effects and dispersion compensation are usually placed at different locations within the cavity, causing the pulse shape to oscillate continuously during cavity circulation, making it difficult to achieve a stable, efficient, and controllable compression process. Therefore, there is an urgent need for an integrated solution that can achieve quasi-synchronous nonlinear spectral broadening and dispersion compensation. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a pulse compression device with end-face dispersion compensation based on slat media that is compact in structure, highly stable, has high media utilization rate and low cost.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an end-face dispersion compensation pulse compression device based on slab medium, comprising an ultrashort pulse laser source, wherein the ultrashort pulse emitted from the ultrashort pulse laser source passes sequentially through a spherical lens and a cylindrical lens, and then sequentially through a first and a second reflecting mirror coated with a high-reflection film to a 45-degree reflecting mirror coated with a dispersion compensation film. The reflected beam is introduced into a coated fused silica slab. Under the condition that the damage threshold of the film and medium is not exceeded, the first and second 0-degree reflecting mirrors coated with dispersion compensation film are used to make the beam pass through a coated fused silica slab multiple times to achieve quasi-synchronous spectral broadening and pulse compression. The pulse-compressed beam is reflected by a third reflecting mirror and then output.

[0006] The beneficial effects of adopting the above technical solution are as follows: The device uses a fused silica slab with a dispersion compensation film coated on the end face as a nonlinear medium, supplemented by beam shaping methods, to achieve quasi-synchronous nonlinear spectral broadening and dispersion compensation. It makes full use of the nonlinear medium and weakens the negative impact of thermal effects on beam quality, thereby achieving compression from picosecond to sub-picosecond and from hundreds of femtoseconds to femtoseconds. It fills the market demand for such high-energy, high-power lasers and has the advantages of compact structure, high stability, high medium utilization, and low cost. Attached Figure Description

[0007] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0008] Figure 1 This is a schematic diagram of the structure of the device described in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the coated fused silica strip in the device described in the embodiment of the present invention; The components are: 1. Ultrashort pulse laser source; 2. Spherical lens; 3. Cylindrical lens; 4. First reflecting mirror; 5. Second reflecting mirror; 6. 45-degree reflecting mirror; 7. Coated fused silica slab; 8. First 0-degree reflecting mirror; 9. Second 0-degree reflecting mirror; 10. Third reflecting mirror; 11. Fused silica slab body; 12. High-transparency film layer. Detailed Implementation

[0009] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0010] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0011] like Figure 1 As shown, this invention discloses an end-face dispersion-compensated pulse compression device based on a slab medium, comprising an ultrashort pulse laser source 1. The ultrashort pulse emitted from the ultrashort pulse laser source 1 passes sequentially through a spherical lens 2 and a cylindrical lens 3, and then sequentially through a first reflecting mirror 4 and a second reflecting mirror 5 coated with a high-reflectivity film, to a 45-degree reflecting mirror 6 coated with a dispersion-compensating film. The spherical lens 2 and the cylindrical lens 3 are used for beam shaping. The beam reflected by the 45-degree dispersion reflecting mirror 6 coated with the dispersion-compensating film is introduced into a coated fused silica slab 7. Under conditions not exceeding the damage threshold of the film and medium, the beam is oscillated multiple times through a quasi-resonant cavity formed by the coated fused silica slab 7, the first 0-degree reflecting mirror 8, and the second 0-degree reflecting mirror 9 coated with the dispersion-compensating film, achieving quasi-synchronous spectral broadening and pulse compression. The pulse-compressed beam is then reflected by a third reflecting mirror 10 and output.

[0012] The external dispersion-compensating mirror consists of a 45-degree reflector 6 coated with a dispersion-compensating film, a first 0-degree reflector 8 coated with a dispersion-compensating film, and a second 0-degree reflector 9 coated with a dispersion-compensating film. This external reflector is positioned in the external optical path, and its reflective surface is coated with a second dispersion-compensating film to provide negative group delay dispersion. The 45-degree reflector 6 is used to introduce the light beam, while the first 0-degree reflector 8 and the second 0-degree reflector 9 are used to allow the light beam to pass through the coated fused silica slab 7 multiple times, resulting in a self-phase modulation effect and achieving spectral broadening. Figure 2 As shown, the coated fused silica strip 7 includes a fused silica strip body 12, one end face of which is coated with a first dispersion compensation film layer 11 and the other end face is coated with a high transmittance film layer 13.

[0013] Furthermore, the coated fused silica slab 7 can be fixed with a copper block to reduce the negative impact of thermal effects on the light spot. Its optical material exhibits third-order nonlinearity and a high laser damage threshold. A first dispersion compensation film 11 is deposited on the first end face of the fused silica slab body 12, ensuring that the beam can be reflected and transmitted, and providing negative group delay dispersion for the laser pulse during the process. An antireflection film 12 is deposited on the second end face of the fused silica slab body 12 to ensure high compression efficiency. The material of the fused silica slab body 12 is fused silica, which has a moderate nonlinear refractive index, an extremely high laser damage threshold, excellent optical uniformity, and thermal stability, making it an ideal material for achieving high-energy pulse compression.

[0014] Furthermore, the total negative group delay dispersion provided by the first dispersion compensation film layer 11 and the external dispersion compensation mirror is equal to the positive group delay dispersion accumulated by the laser pulse through multiple round trips within the coated fused silica slab 7. Further, the first dispersion compensation film layer 11 can be a Gires-Tournois interferometer structure, providing negative group delay dispersion, and consists of a partial reflection layer, a total reflection layer, and an optically thick layer between them. It consists of spacer layers. The GTI structure can provide smooth and large negative group delay dispersion in a specific band while ensuring extremely high reflectivity (>99.9%), making it an ideal choice for achieving end-face reflection dispersion compensation.

[0015] Furthermore, the 45-degree reflector 6, the first 0-degree reflector 8, and the second 0-degree reflector 9 coated with dispersion compensation film can provide negative group retardation dispersion. The amount of negative group retardation dispersion provided is compatible with the first dispersion compensation film and the introduced positive dispersion. If the required dispersion compensation is extremely large during large-span compression, it can be used in conjunction with a dispersion compensation device.

[0016] The coated fused silica slab 7 and the external dispersion compensation mirror together form a resonant cavity structure. The laser pulse passes through the coated fused silica slab 7 multiple times within this cavity. Each round trip passes through the positive dispersion introduced by the coated fused silica slab 7 and the self-phase modulation effect, and the negative dispersion introduced by the first dispersion compensation film layer 11 and the second dispersion compensation film layer on the external dispersion compensation mirror, thereby achieving quasi-synchronous nonlinear spectral broadening and pulse compression.

[0017] This invention also discloses a method for end-face dispersion compensation pulse compression based on slat media. The method uses the end-face dispersion compensation pulse compression device and includes the following steps: The spot pattern is designed based on the damage threshold of the first dispersion compensation film 11 and the second dispersion compensation film. Without causing damage to the film and the fused silica slab body 12, the beam is shaped by a lens group consisting of a spherical lens 2 and a cylindrical lens 3. The output spot size of the ultrashort pulse laser source 1 is collimated to 0.8-1 mm in the X-axis direction and focused in the Y-axis direction. An ultrashort laser pulse is coupled from one side of a 45-degree reflector 6 coated with a dispersion compensation film into a quasi-resonant cavity consisting of a coated fused silica slab 7 and a first 0-degree reflector 8 and a second 0-degree reflector 9 coated with a dispersion compensation film. The pulse travels back and forth in the cavity multiple times. Each time it passes through the coated fused silica slab 7 in a single trip, its spectrum is broadened by the self-phase modulation effect, and positive group delay dispersion is accumulated. Each time the pulse is reflected by the first dispersion compensation film layer 11 on the coated fused silica slab 7 and the external dispersion compensation mirror, negative group delay dispersion compensation is obtained respectively. By designing the length, nonlinear characteristics, and dispersion amount of the first and second dispersion compensation layers of the coated fused silica strip 7, the positive dispersion accumulated by the pulse in each round trip cycle is approximately canceled out, thereby achieving pulse width compression while the pulse spectrum is broadened. After a predetermined number of round trips, a pulse with optimal spectral width and compression is obtained and coupled out.

[0018] In summary, the method uses fused silica slabs with a dispersion compensation medium film coated on the end face as a nonlinear medium, supplemented by beam shaping techniques, to achieve quasi-synchronous nonlinear spectral broadening and dispersion compensation. It makes full use of the nonlinear medium and reduces the negative impact of thermal effects on beam quality, thereby compressing the beam size from picosecond to sub-picosecond and from hundreds of femtoseconds to femtoseconds, filling the market demand for such high-energy, high-power lasers.

[0019] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0020] This application uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. In summary, the content of this specification should not be construed as a limitation of this application.

Claims

1. A pulse compression device with end-face dispersion compensation based on slat media, characterized in that: The system includes an ultrashort pulse laser source (1). The ultrashort pulse emitted from the ultrashort pulse laser source (1) passes through a spherical lens (2) and a cylindrical lens (3) in sequence, and then passes through a first reflector (4) and a second reflector (5) coated with a high-reflection film in sequence to a 45-degree reflector (6) coated with a dispersion compensation film. The reflected beam is introduced into a coated fused silica slab (7). Under the condition that the damage threshold of the film and the medium is not exceeded, the first 0-degree reflector (8) and the second 0-degree reflector (9) coated with a dispersion compensation film are used to make the beam pass through a coated fused silica slab (7) multiple times to achieve quasi-synchronous spectral broadening and pulse compression. The pulse-compressed beam is reflected by a third reflector (10) and then output.

2. The end-face dispersion compensation pulse compression device based on slat medium as described in claim 1, characterized in that: The spherical lens (2) and cylindrical lens (3) are used for spot shaping.

3. The end-face dispersion compensation pulse compression device based on slat media as described in claim 1, characterized in that: The coated fused silica strip (7) includes a fused silica strip body (12), one end face of which is coated with a first dispersion compensation film layer (11) and the other end face is coated with a high-transparency film layer (13).

4. The end-face dispersion compensation pulse compression device based on slat medium as described in claim 3, characterized in that: The 45-degree reflector (6) coated with a dispersion compensation film, the first 0-degree reflector (8) coated with a dispersion compensation film, and the second 0-degree reflector (9) coated with a dispersion compensation film constitute an external dispersion compensation reflector, which is set in the external optical path. Its reflective surface is coated with a second dispersion compensation film to provide negative group delay dispersion. The 45-degree reflector (6) coated with a dispersion compensation film is used to introduce the light beam. The first 0-degree reflector (8) and the second 0-degree reflector (9) coated with a dispersion compensation film are used to make the light beam pass through the coated fused silica slab (7) multiple times to produce a self-phase modulation effect, so as to achieve the effect of spectral broadening.

5. The end-face dispersion compensation pulse compression device based on slat medium as described in claim 4, characterized in that: The total negative group delay dispersion provided by the first dispersion compensation film layer (11) and the external dispersion compensation mirror is equal to the positive group delay dispersion accumulated by the laser pulse traveling back and forth multiple times within the coated fused silica slab (7).

6. The end-face dispersion compensation pulse compression device based on slat media as described in claim 3, characterized in that: The first dispersion compensation film layer (11) is a Gires-Tournois interferometer structure used to provide negative group delay dispersion.

7. The end-face dispersion compensation pulse compression device based on slat media as described in claim 4, characterized in that: The 45-degree mirror (6), the first 0-degree mirror (8), and the second 0-degree mirror (9) coated with a dispersion compensation film are coated to provide negative group delayed dispersion.

8. The end-face dispersion compensation pulse compression device based on slat medium as described in claim 1, characterized in that: The coated fused silica strip (7) is fixed by a copper block to reduce the negative impact of thermal effect on the light spot.

9. The end-face dispersion compensation pulse compression device based on slat medium as described in claim 4, characterized in that: The coated fused silica slab (7) and the external dispersion compensation mirror together form a resonant cavity structure. The laser pulse passes through the coated fused silica slab multiple times in this cavity. Each round trip passes through the positive dispersion introduced by the coated fused silica slab and the self-phase modulation effect and the negative dispersion introduced by the first dispersion compensation film layer (11) and the second dispersion compensation film layer on the external dispersion compensation mirror, so as to achieve quasi-synchronous nonlinear spectral broadening and pulse compression.

10. A method for end-face dispersion compensation pulse compression based on slat media, wherein the method uses the end-face dispersion compensation pulse compression device based on slat media as described in any one of claims 1-9, characterized in that... The method includes the following steps: The beam pattern is designed based on the damage threshold of the first dispersion compensation film (11) and the second dispersion compensation film. Without causing damage to the film and the fused silica slab body (12), the beam is shaped by a lens group consisting of a spherical lens (2) and a cylindrical lens (3). The output beam size of the ultrashort pulse laser source (1) is collimated to 0.8-1 mm in the X-axis direction and focused in the Y-axis direction. An ultrashort laser pulse is coupled from one side of a 45-degree reflector (6) coated with a dispersion compensation film into a quasi-resonant cavity composed of a coated fused silica slab (7) and a first 0-degree reflector (8) and a second 0-degree reflector (9) coated with a dispersion compensation film. The pulse travels back and forth in the cavity multiple times. Each time it passes through the coated fused silica slab (7) in a single trip, its spectrum is broadened by the self-phase modulation effect, and positive group delay dispersion is accumulated. Each time the pulse is reflected by the first dispersion compensation film layer (11) on the coated fused silica slab (7) and the external dispersion compensation mirror, negative group delay dispersion compensation is obtained respectively. By designing the length, nonlinear characteristics, and dispersion amount of the first and second dispersion compensation layers of the coated fused silica strip (7), the positive dispersion accumulated by the pulse in each round trip cycle is approximately canceled out, thereby achieving pulse width compression while the pulse spectrum is broadened. After a predetermined number of round trips, a pulse with optimal spectral width and compression is obtained and coupled out.

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