Femtosecond laser pulse compression device

Abstract

The utility model discloses a femtosecond laser pulse compression device. The device comprises an amplifier, a half-wave plate and a transmission-type compression grating which are sequentially arranged along a light path, a first climbing mirror and a second climbing mirror are arranged on a diffraction light path on one side of the transmission-type compression grating, and a third climbing mirror and a leading-out reflector are arranged on a diffraction light path on the other side of the transmission-type compression grating; and a cylindrical lens group is arranged between the transmission-type compression grating and the first climbing mirror and the second climbing mirror. According to the technical scheme, a single grating is matched with a plurality of climbing mirrors to form a laser turn-back system, compression of laser pulses is completed under the condition that the size of the laser pulse compression device is greatly reduced through a simple structure, a large dispersion providing amount can be achieved within a short optical path length through further arrangement of a cylindrical lens set, and therefore the laser pulse compression device has the advantages of being simple in structure, convenient to operate and high in efficiency. The set size of the device is further reduced, the miniaturization design of the femtosecond laser pulse compression device is facilitated, and the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser, in particular to a femtosecond laser pulse compression device. BACKGROUND

[0002] Femtosecond laser has the characteristics of ultra-short pulse width and high peak power, and has wide application in industrial manufacturing field and scientific research field. In order to obtain femtosecond pulses with higher energy, the femtosecond pulse is usually amplified by using the chirped pulse amplification technology. The seed light is first expanded by an expander, then injected into an amplifier for amplification, and after the amplification is completed, the dispersion is compensated by a compressor to realize the output of femtosecond pulses close to the transform limit.

[0003] At present, the compression device for pulse compression mainly includes a double-grating structure and a single-grating structure. Among them, the double-grating structure is usually large in size, and adopts two gratings, so the overall cost is high. The single-grating structure has smaller overall size and cost compared with the double-grating structure. In the existing single-grating compression structure, such as the femtosecond laser pulse compression device and method disclosed in patent application No. CN202010376656.9, the laser pulse passes through the first grating, and then the linear light spot is hit back to the grating through two reflecting mirrors, so as to realize pulse compression through a single grating. However, since the linear light spot is divided into left and right sides and hit on the grating, the requirement for the transverse size of the grating is high, and devices such as a polarization beam splitter and a rotator need to be added, which undoubtedly increases the cost.

[0004] Therefore, it is necessary to further improve the structure of the single-grating compressor. CONTENT OF THE UTILITY MODEL

[0005] The present application provides a femtosecond laser pulse compression device, which aims to solve the problems of large size and high cost of the pulse compression device in the prior art.

[0006] In order to achieve the above-mentioned purpose, the present application provides a femtosecond laser pulse compression device. The femtosecond laser pulse compression device comprises an amplifier, a half-wave plate and a transmission type compression grating arranged in sequence along an optical path; a first climbing mirror and a second climbing mirror are arranged on one side of the transmission type compression grating, and a third climbing mirror and a guide-out mirror are arranged on the other side of the transmission type compression grating.

[0007] The laser pulse output by the amplifier passes through the half-wave plate and is incident on the transmission compression grating for the first time at the grating blazed angle corresponding to the center wavelength. After diffraction by the grating, the laser pulse is incident on the first climbing mirror. After height adjustment and reflection by the first climbing mirror, the laser pulse is incident on the transmission compression grating for the second time and is diffracted to the third climbing mirror. After height adjustment and reflection by the third climbing mirror, the laser pulse is incident on the transmission compression grating for the third time and is diffracted to the second climbing mirror. After height adjustment and reflection by the second climbing mirror, the laser pulse is incident on the transmission compression grating for the fourth time and is diffracted to the extraction mirror and is reflected by the extraction mirror to be output.

[0008] The transmission compression grating is provided with a cylindrical lens group between the first climbing mirror and the second climbing mirror. The laser pulse passes through the cylindrical lens group when propagating back and forth between the transmission compression grating and the first climbing mirror and the second climbing mirror. The cylindrical lens group is used to increase the dispersion amount.

[0009] In some embodiments, the cylindrical lens group includes a first cylindrical lens group and a second cylindrical lens group arranged in mirror image. The first cylindrical lens group is arranged between the transmission compression grating and the first climbing mirror, and the second cylindrical lens group is arranged between the transmission compression grating and the second climbing mirror.

[0010] In some embodiments, the first cylindrical lens group and the second cylindrical lens group each include a convex cylindrical lens and a concave cylindrical lens.

[0011] The laser pulse is incident on the concave cylindrical lens after being diffracted by the transmission compression grating for the first time, is incident on the first climbing mirror after passing through the concave cylindrical lens, is reflected by the first climbing mirror to the convex cylindrical lens, and is incident on the transmission compression grating for the second time after passing through the convex cylindrical lens.

[0012] The third time, the laser pulse diffracted by the grating is incident on the convex cylindrical lens, is incident on the second climbing mirror after passing through the convex cylindrical lens, is reflected by the second climbing mirror to the concave cylindrical lens, and is incident on the transmission compression grating for the fourth time after passing through the concave cylindrical lens.

[0013] In some embodiments, in the first cylindrical lens group and the second cylindrical lens group, the optical path distance between the convex cylindrical lens and the concave cylindrical lens is the sum of the focal lengths of the two.

[0014] In some embodiments, in the first cylindrical lens group and the second cylindrical lens group, the focal length of the concave cylindrical lens is -100 mm, the focal length of the convex cylindrical lens is 200 mm, and the transmittance of each cylindrical lens is greater than 99.9%.

[0015] In some embodiments, the grating density of the transmissive compression grating is 1000-2000 l / mm, the working wavelength is 1000-1100 nm, the grating length is 3-10 cm, the height is 2-4 cm, and the single loss is less than 2%.

[0016] In some embodiments, the first climbing mirror, the second climbing mirror, and the third climbing mirror each include a first reflecting mirror and a second reflecting mirror whose reflected light paths are perpendicular to each other.

[0017] In some embodiments, the operating wavelengths of the outgoing reflector, the first reflector, and the second reflector are all in the range of 1000–1100 nm, and the reflectivity is greater than 99.9%.

[0018] In some embodiments, the amplifier is a chirped pulse amplification system with an output pulse width of 100 ps to 1 ns, an output center wavelength of 1020 to 1050 nm, and an output spectral width of 2 to 50 nm.

[0019] In some embodiments, the operating wavelength range of the half-wave plate is 1000–1100 nm.

[0020] This application proposes a femtosecond laser pulse compression device. The device includes an amplifier, a half-wave plate, and a transmissive compression grating arranged sequentially along the optical path. A first and second ascending mirror are positioned on one side of the diffraction path of the transmissive compression grating, and a third ascending mirror and a lead-out mirror are positioned on the other side. A cylindrical lens group is positioned between the transmissive compression grating and the first and second ascending mirrors, and the laser propagation path is further configured. This application's technical solution uses a single transmissive compression grating combined with multiple ascending mirrors to form a laser reflection system. With a simple structural design, the size of the laser pulse compression device can be greatly reduced while compressing the laser pulse. Furthermore, by using a cylindrical lens group, a large amount of dispersion can be provided within a short optical path length, thus further reducing the overall size of the device and facilitating miniaturization and cost reduction of the femtosecond laser pulse compression device. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0022] Figure 1 This is a schematic diagram of the structure of a femtosecond laser pulse compression device according to an embodiment of this application;

[0023] Figure 2 This is a schematic diagram illustrating the working principle of a femtosecond laser pulse compression device according to an embodiment of this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application 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 this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0026] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.

[0027] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0028] See Figure 1 As shown, this application proposes a femtosecond laser pulse compression device. The femtosecond laser pulse compression device includes an amplifier 10, a half-wave plate 20, and a transmission compression grating 30 arranged sequentially along the optical path.

[0029] In this application's technical solution, amplifier 10 amplifies the power and energy of the laser pulse. The pulse is broadened before entering amplifier 10 to reduce its peak power, thereby preventing damage to the gain medium and other optical components in amplifier 10 during amplification and more effectively extracting energy from the laser medium, thus increasing the laser pulse's energy. Half-wave plate 20 adjusts the polarization state of the light wave, causing it to incident on the transmission compression grating 30 at a specific angle. The transmission compression grating 30 compresses the laser pulse in time and space through diffraction, significantly increasing the peak power of the pulse at the same energy level, resulting in higher processing efficiency and better processing quality.

[0030] Amplifier 10 is a chirped pulse amplification system with an output pulse width of 100 ps to 1 ns, an output center wavelength of 1020 to 1050 nm, and an output spectral width of 2 to 50 nm. Half-wave plate 20 operates in the wavelength range of 1000 to 1100 nm. Transmission-type compression grating 30 has a scribe line density of 1000 to 2000 l / mm, an operating wavelength of 1000 to 1100 nm, a grating length of 3 to 10 cm, a height of 2 to 4 cm, and a single-pass loss of less than 2%. These parameters collectively define the optical performance of amplifier 10, half-wave plate 20, and transmission-type compression grating 30, ensuring the efficient operation of the entire femtosecond laser pulse compression device. In practical applications, appropriate parameter combinations can be selected according to specific needs and scenarios to achieve the best laser pulse compression effect.

[0031] See Figure 1 As shown, to achieve the pulse compression process, a first climbing mirror 41 and a second climbing mirror 42 are arranged on one side of the diffraction path of the transmissive compression grating 30, and a third climbing mirror 50 and a guide mirror 70 are arranged on the other side of the diffraction path; the first climbing mirror 41, the second climbing mirror 42, and the third climbing mirror 50 combine to form a beam refracting system. This achieves:

[0032] The laser output from amplifier 10, after passing through half-wave plate 20, is incident on transmission compression grating 30 at a grating blaze angle corresponding to the center wavelength, ensuring high diffraction efficiency when the laser pulse is incident on the grating. After diffraction by the grating, it is incident on the first ascending mirror 41. After height adjustment and reflection by the first ascending mirror 41, it is incident on the transmission compression grating 30 a second time and diffracted to the third ascending mirror 50. After height adjustment and reflection by the third ascending mirror 50, it is incident on the transmission compression grating 30 a third time and diffracted to the second ascending mirror 42. After height adjustment and reflection by the second ascending mirror 42, it is incident on the transmission compression grating 30 a fourth time and diffracted to the output mirror 70, and then reflected out by the output mirror 70. In this way, the laser pulse is refracted four times, and each time it passes through the transmission compression grating 30, it is further compressed, ultimately increasing the peak power of the laser pulse.

[0033] Thus, through the above structural configuration, the femtosecond laser pulse compression device proposed in this application achieves laser pulse compression based on a single-transmission compression grating 30, thereby greatly reducing the size (approximately half that of a dual-grating structure) and cost of the laser pulse compression device.

[0034] In addition, a cylindrical lens group 60 is provided between the transmissive compression grating 30 and the first climbing mirror 41 and the second climbing mirror 42. When the laser pulse propagates back and forth between the transmissive compression grating 30 and the first climbing mirror 41 and the second climbing mirror 42, it passes through the cylindrical lens group 60. The cylindrical lens group 60 is used to improve the dispersion.

[0035] Understandably, the essence of laser pulse compression is to spatially separate the different frequency components in the laser pulse to form a certain amount of dispersion, and then, during the compression process, to make these different frequency components re-converge, thereby achieving laser pulse compression.

[0036] Therefore, this application improves the dispersion by further configuring the cylindrical lens group 60, thereby achieving a higher dispersion at the same optical path distance compared to the traditional configuration. This means that the cylindrical lens group 60 can shorten the distance between the transmissive compression grating 30 and the first and second climbing mirrors 41 and 42, reducing the overall length of the device and further miniaturizing its size. This facilitates the miniaturization of the laser pulse compression device and reduces costs.

[0037] See Figure 1 As shown, in some embodiments, the cylindrical lens group 60 includes a first cylindrical lens group 61 and a second cylindrical lens group 62 that are mirror images of each other; the first cylindrical lens group 61 is correspondingly disposed between the transmissive compression grating 30 and the first climbing mirror 41, and the second cylindrical lens group 62 is correspondingly disposed between the transmissive compression grating 30 and the second climbing mirror 42.

[0038] In this embodiment, the first cylindrical lens group 61 and the second cylindrical lens group 62 are arranged in a mirror image. The main purpose is to consider the symmetry of the optical path so that after the beam passes through the first cylindrical lens group 61, the beam can cancel each other out when it passes through the second cylindrical lens group 62. That is, the beam can return along the original optical path so that after passing through the grating four times, the beam can refocus into a single point and be emitted.

[0039] Furthermore, both the first cylindrical lens group 61 and the second cylindrical lens group 62 include a convex cylindrical lens and a concave cylindrical lens. For example... Figure 1As shown, the first cylindrical lens group 61 includes a first concave cylindrical lens 611 and a first convex cylindrical lens 612, and the second cylindrical lens group 62 includes a second convex cylindrical lens 621 and a second concave cylindrical lens 622. According to the optical path sequence, the laser pulse is first incident on the transmissive compression grating 30 and diffracted, then incident on the first concave cylindrical lens 611, then on the first climbing mirror 41, and reflected by the first climbing mirror 41 to the first convex cylindrical lens 612, then incident on the transmissive compression grating 30 for the second time; and the laser pulse, diffracted by the grating for the third time, is incident on the second convex cylindrical lens 621, then on the second climbing mirror 42, and reflected by the second climbing mirror 42 to the second concave cylindrical lens 622, then incident on the transmissive compression grating 30 for the fourth time. The specific workflow of the femtosecond laser pulse compression device proposed in this application can be found in [reference needed]. Figure 2 The diagram shown illustrates the working principle.

[0040] In terms of optical path sequence, the first cylindrical lens group 61 is designed with a concave cylindrical lens followed by a convex cylindrical lens, while the second cylindrical lens group 62 is designed with a convex cylindrical lens followed by a concave cylindrical lens. After the first diffraction, the laser pulse can be further amplified in space by the first concave cylindrical lens 611, thus providing more dispersion over the same length. After height adjustment and reflection by the first climbing mirror 41, the first convex cylindrical lens 612 corrects the effect of the first concave cylindrical lens 611 on the beam divergence. In the second cylindrical lens group 62, the laser pulse passes through the reverse cylindrical lens design sequentially.

[0041] In some embodiments, in the first cylindrical lens group 61 and the second cylindrical lens group 62, the optical path distance between the convex cylindrical lens and the concave cylindrical lens is the sum of their focal lengths. This ensures that the laser pulse originating from the focal point of the concave or convex cylindrical lens, passes through the convex or concave cylindrical lens, and then converges back to the focal point of the convex or concave cylindrical lens, thus maintaining a specific beam emissivity.

[0042] In one specific configuration, in the first cylindrical lens group 61 and the second cylindrical lens group 62, the focal length of the concave cylindrical lens is -100mm, and the focal length of the convex cylindrical lens is 200mm, with each cylindrical lens having a transmittance greater than 99.9%. Thus, the concave cylindrical lens has a significant diverging effect on light, causing the laser pulse to diverge rapidly after passing through it. Furthermore, since both the concave and convex cylindrical lenses have high transmittance, it ensures that the laser pulse maintains its energy and intensity as it passes through the lens group.

[0043] The first climbing mirror 41 and the second climbing mirror 42 are combined on one side of the transmissive compression grating 30 to form a climbing mirror assembly 40. The dispersion provided can be adjusted by adjusting the distance between the cylindrical lens assembly 60 and the climbing mirror assembly 40 as a whole and the transmissive compression grating 30. There are no special requirements for the distance between the third climbing mirror 50 and the lead-out mirror 70 and the transmissive compression grating 30, as long as it does not exceed the distance between the half-wave plate 20 and the transmissive compression grating 30.

[0044] See Figure 1 As shown, in some embodiments, the first climbing mirror 41, the second climbing mirror 42, and the third climbing mirror 50 all include a first reflecting mirror and a second reflecting mirror with the reflected light path perpendicular to each other. This can change the propagation direction of the laser pulse, allowing the laser pulse to propagate in the system along a predetermined trajectory while maintaining the compactness and stability of the optical path. Furthermore, the operating wavelengths of the derived reflecting mirror 70, the first reflecting mirror, and the second reflecting mirror are all in the range of 1000–1100 nm, and the reflectivity is greater than 99.9%. The operating wavelengths are suitable for the operation of femtosecond lasers, and the high reflectivity ensures that the laser pulse reduces beam distortion and scattering during multiple reflections, maintaining sufficient energy and stability.

[0045] The above description is only a part or preferred embodiment of this application. Neither the text nor the drawings should limit the scope of protection of this application. All equivalent structural transformations made using the content of this application's specification and drawings under the overall concept of this application, or direct / indirect applications in other related technical fields, are included within the scope of protection of this application.

Claims

1. A femtosecond laser pulse compression device, characterized in that, It includes an amplifier, a half-wave plate, and a transmissive compression grating arranged sequentially along the optical path; a first climbing mirror and a second climbing mirror are provided on one side of the diffraction optical path of the transmissive compression grating, and a third climbing mirror and a lead-out reflection mirror are provided on the other side of the diffraction optical path. The laser pulse output by the amplifier passes through the half-wave plate and is first incident on the transmissive compression grating at the grating blaze angle corresponding to the center wavelength. After diffraction by the grating, it is incident on the first climbing mirror. After height adjustment and reflection by the first climbing mirror, it is incident on the transmissive compression grating for the second time and diffracted to the third climbing mirror. After height adjustment and reflection by the third climbing mirror, it is incident on the transmissive compression grating for the third time and diffracted to the second climbing mirror. After height adjustment and reflection by the second climbing mirror, it is incident on the transmissive compression grating for the fourth time and diffracted to the output mirror, and is then reflected and output by the output mirror. A cylindrical lens group is provided between the transmissive compression grating and the first and second climbing mirrors. When the laser pulse propagates back and forth between the transmissive compression grating and the first and second climbing mirrors, it passes through the cylindrical lens group. The cylindrical lens group is used to improve the dispersion.

2. The femtosecond laser pulse compression device according to claim 1, characterized in that, The cylindrical lens group includes a first cylindrical lens group and a second cylindrical lens group that are mirror images of each other; the first cylindrical lens group is correspondingly disposed between the transmissive compression grating and the first climbing mirror, and the second cylindrical lens group is correspondingly disposed between the transmissive compression grating and the second climbing mirror.

3. The femtosecond laser pulse compression device according to claim 2, characterized in that, Both the first cylindrical lens group and the second cylindrical lens group include a convex cylindrical lens and a concave cylindrical lens. Specifically, after the laser pulse is first incident on the transmissive compression grating and diffracted, it is incident on the concave cylindrical lens, then on the first climbing mirror, and reflected by the first climbing mirror to the convex cylindrical lens, then on the transmissive compression grating a second time; and... The third laser pulse diffracted by the grating is incident on the convex cylindrical lens, then on the second climbing mirror, and reflected by the second climbing mirror to the concave cylindrical lens. After passing through the concave cylindrical lens, it is incident on the transmissive compression grating for the fourth time.

4. The femtosecond laser pulse compression device according to claim 3, characterized in that, In the first cylindrical lens group and the second cylindrical lens group, the optical path distance between the convex cylindrical lens and the concave cylindrical lens is the sum of their focal lengths.

5. The femtosecond laser pulse compression device according to claim 4, characterized in that, In the first cylindrical lens group and the second cylindrical lens group, the focal length of the concave cylindrical lens is -100mm, the focal length of the convex cylindrical lens is 200mm, and the transmittance of each cylindrical lens is greater than 99.9%.

6. The femtosecond laser pulse compression device according to claim 1, characterized in that, The transmission-type compression grating has a grating density of 1000-2000 l / mm, a working wavelength of 1000-1100nm, a grating length of 3-10cm, a height of 2-4cm, and a single loss of less than 2%.

7. The femtosecond laser pulse compression device according to claim 1, characterized in that, The first climbing mirror, the second climbing mirror, and the third climbing mirror all include a first reflecting mirror and a second reflecting mirror whose reflected light paths are perpendicular.

8. The femtosecond laser pulse compression device according to claim 7, characterized in that, The operating wavelengths of the outgoing reflector, the first reflector, and the second reflector are all in the range of 1000–1100 nm, and their reflectivity is greater than 99.9%.

9. The femtosecond laser pulse compression device according to claim 1, characterized in that, The amplifier is a chirped pulse amplification system with an output pulse width of 100ps to 1ns, an output center wavelength of 1020 to 1050nm, and an output spectral width of 2 to 50nm.

10. The femtosecond laser pulse compression device according to claim 1, characterized in that, The operating wavelength range of the half-wave plate is 1000–1100 nm.

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