A stacked laser pulse compression device

Abstract

This invention discloses a stacked laser pulse compression device, relating to the field of ultrafast laser technology. It includes: first, second, third, and fourth optical path layers arranged parallel to an optical substrate in sequence according to their height; a transmission diffraction grating assembly disposed within the common optical path region of the four optical path layers; a mirror group that guides the beam back within each optical path layer, ensuring the beam passes through the transmission diffraction grating assembly twice within each layer; a first height conversion component that transfers the beam from the first optical path layer to the fourth optical path layer and from the third optical path layer to the second optical path layer; and a second height conversion component that transfers the beam from the fourth optical path layer to the third optical path layer. This invention employs a four-layer, eight-pass stacked structure, increasing the number of grating passes and dispersion compensation without significantly increasing the lateral footprint, making it suitable for compact chirped pulse amplification (CPA) systems.

Description

Technical Field

[0001] This invention belongs to the field of ultrafast laser technology, and specifically relates to a stacked laser pulse compression device. Background Technology

[0002] Ultra-intense, ultra-short pulse lasers have important applications in fields such as high-field physics, inertial confinement fusion, precision materials processing, and ultrafast spectroscopy. Chirped pulse amplification (CPA) is the mainstream technology for generating high peak power ultra-short pulses. As the terminal of the CPA system, the pulse compressor's compression quality and volume directly affect the overall performance and engineering practicality of the system.

[0003] Existing pulse compressors generally employ a Treacy grating pair structure. A standard four-pass transmission grating compressor typically includes two parallel transmission diffraction gratings and a reflective element. The beam propagates back and forth between the two gratings, utilizing the angular dispersion characteristics of the gratings to introduce the desired group delay dispersion, thereby achieving time-domain compression. In this structure, a complete four-pass compression unit relies on two spatially staggered optical paths to achieve four passes of the beam.

[0004] In practical applications, the number of times the grating in the above structure can be reused is limited. The beam can only pass through the transmission grating four times in a single compression cycle, resulting in low dispersion compensation. If the system requires a larger dispersion compensation to compress shorter pulses, it is necessary to increase the grating spacing or extend the optical path folding length. However, under high-power conditions, in order to avoid damage to the grating and optical components due to excessive power density, the beam aperture must be enlarged to ensure the light transmission aperture. This further forces the optical path reflection mirror and the size of the mounting structure to be enlarged simultaneously. Therefore, this significantly increases the compressor's footprint, making it difficult to meet the development trend of CPA systems towards compactness and mobile platform deployment. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problem that existing pulse compressors have a drastic increase in volume due to the need to increase dispersion compensation, and to propose a stacked laser pulse compression device.

[0006] In this embodiment of the invention, a stacked laser pulse compression device is proposed, the device comprising an optical substrate, a transmission diffraction grating assembly, a first height conversion assembly, a second height conversion assembly, and a mirror group; The first optical path layer, the second optical path layer, the third optical path layer, and the fourth optical path layer are arranged in sequence according to their height, parallel to the optical substrate. The transmission diffraction grating assembly is disposed in the common optical path area of ​​the first optical path layer, the second optical path layer, the third optical path layer and the fourth optical path layer, so that the light beam can pass through the transmission diffraction grating assembly when it propagates in the four optical path layers. The mirror assembly is configured to guide the beam back in each optical path layer so that the beam passes through the transmission diffraction grating assembly twice in each optical path layer. The first height conversion component is configured to transfer the beam from the first optical path layer to the fourth optical path layer, and from the third optical path layer to the second optical path layer; The second height conversion component is configured to transfer the beam from the fourth optical path layer to the third optical path layer.

[0007] Optionally, the device also includes an inlet and an outlet; the inlet is connected to the first optical path layer and is used to guide the incident light beam into the first optical path layer; the outlet is connected to the second optical path layer and is used to output the compressed pulse after multiple transmission gratings have passed through; the inlet and outlet are located on the same side or opposite side of the device and are spatially separated by height difference, lateral offset or angular offset.

[0008] Optionally, the reflector group includes a common reflector, which includes a first common reflector, a second common reflector, and a third common reflector; The first common reflector, the second common reflector, and the third common reflector penetrate the first optical path layer, the second optical path layer, the third optical path layer, and the fourth optical path layer in a direction perpendicular to the optical substrate. The reflecting surface of the second common reflector forms a 90° angle with the reflecting surface of the third common reflector.

[0009] Optionally, the reflector assembly includes layered reflectors, which include a first layered reflector and a second layered reflector. The first layered reflector is located in the second optical path layer and is used to guide the light beam after two grating passes in the second optical path layer to the light outlet. The second layered reflector is located at a height between the third and fourth optical path layers and is a shared reflector for the third and fourth optical path layers. It is used in conjunction with the shared reflector to complete the beam reflection in the third and fourth optical path layers respectively.

[0010] Optionally, the first height conversion component is disposed between the first optical path layer and the fourth optical path layer, and between the third optical path layer and the second optical path layer; The first optical path layer and the fourth optical path layer form a first group of four-pass compression units by multiplexing the first height conversion component, and the third optical path layer and the second optical path layer form a second group of four-pass compression units by multiplexing the first height conversion component. The second height conversion component is connected between the fourth optical path layer and the third optical path layer so that the first group of four-pass compression units and the second group of four-pass compression units are connected in series along the optical path, so that the beam propagates sequentially through the first optical path layer, the fourth optical path layer, the third optical path layer and the second optical path layer, and passes through the transmission diffraction grating component twice in each optical path layer, for a total of eight times.

[0011] Optionally, the first height transformation component and the second height transformation component are height transformation mirror groups. The height transformation mirror group includes a first mirror surface and a second mirror surface. The first mirror surface and the second mirror surface are provided with a non-zero included angle, and the connecting line between the lower vertex of the first mirror surface and the upper vertex of the second mirror surface is perpendicular to the optical substrate. The first mirror is used to receive the light beam and reflect it to the second mirror. The second mirror is used to receive the light beam from the first mirror, reflect the light beam a second time, and output it, so that the light beam can realize optical path layer conversion in the first optical path layer, the fourth optical path layer, the third optical path layer, and the second optical path layer by utilizing the reflection characteristics of the first and second mirrors.

[0012] Optionally, the first height transformation component is a height transformation prism, which includes a reflective surface angle, and the median plane of the reflective surface angle is set to be parallel to the optical substrate; the first optical path layer and the fourth optical path layer are symmetrical about the median plane of the angle, and the second optical path layer and the third optical path layer are symmetrical about the median plane of the angle. The second height conversion component is a height conversion prism, and the mid-angle plane corresponding to the included angle of the reflective surface in the height conversion prism is set to be parallel to the optical substrate; the fourth optical path layer and the third optical path layer are symmetrical about the mid-angle plane.

[0013] Optionally, the reflection mode of the height-changing prism includes any one of total internal reflection, metallic film reflection, or dielectric high-reflection film reflection; The transmission diffraction grating assembly is configured as a transmission grating of any one of volume holographic grating, surface relief grating, or multilayer dielectric film grating.

[0014] The beneficial effects of this invention are: 1. This application stacks two complete four-pass compression units in series in the height direction to form four height optical path layers, from the first to the fourth. The light beam propagates sequentially through the first, fourth, third, and second optical path layers, and passes through the transmission diffraction grating assembly twice in each optical path layer, for a total of eight times. This doubles the effective light transmission number of the grating compared to the standard four-pass structure and doubles the equivalent dispersion compensation. Furthermore, each optical path layer reuses the same spatial area in the top-view projection and is separated from each other in the height direction. Thus, without significantly increasing the lateral footprint, this application solves the problem of rapid volume expansion caused by traditional compressors having to increase the grating spacing or extend the planar folded optical path to improve dispersion. This provides key terminal support for the miniaturization of CPA systems and deployment on mobile platforms. 2. This application uses a first height conversion component to simultaneously handle the interlayer transition between the first to fourth and third to second optical path layers, and a second height conversion component to connect the fourth and third optical path layers. Only two cross-layer elements are needed to connect two four-pass compression units into a complete four-layer eight-pass optical path, which significantly reduces the number of mirrors and the number of independent adjustable degrees of freedom. At the same time, each layer shares the same transmission diffraction grating component and a common mirror group that runs through the four layers. The 90° perpendicular relationship between the second and third common mirrors can be achieved by a one-time solidification process using an integral prism. Only a few optical degrees of freedom need to be calibrated on-site to complete the closing and debugging of all eight optical paths. This significantly reduces the alignment complexity and cumulative wavefront error of the multi-pass multiplexing system, and improves the assembly consistency, long-term operational stability, and feasibility of industrial mass production of the compressor. Attached Figure Description

[0015] The invention will now be further described with reference to the accompanying drawings.

[0016] Figure 1 A stacked laser pulse compression device is provided as an embodiment of the present invention; Figure 2 This is a schematic diagram of the internal structure of the height transformation component provided in an embodiment of the present invention; Figure 3 This invention provides a schematic diagram of the compression optical path of a stacked laser pulse compression device according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the beam propagation process of a stacked laser pulse compression device provided in an embodiment of the present invention; The labels in the diagram represent the following: 100, optical substrate; 101, light inlet; 102, first layered mirror; 103, second layered mirror; 104, first common mirror; 105, transmission diffraction grating assembly; 106, second common mirror; 107, third common mirror; 108, first height conversion assembly; 109, second height conversion assembly; 110, light outlet; 203, first optical path layer; 204, second optical path layer; 205, third optical path layer; 206, fourth optical path layer; 301, first mirror surface; 302, second mirror surface; 303, lower vertex of the first mirror surface; 304, upper vertex of the second mirror surface. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] 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.

[0019] Example 1

[0020] This invention provides a stacked laser pulse compression device. See also... Figure 1 The device specifically includes: an optical substrate 100, a transmission diffraction grating assembly 105, a first height conversion assembly 108, a second height conversion assembly 109, and a mirror group; a first optical path layer 203, a second optical path layer 204, a third optical path layer 205, and a fourth optical path layer 206 are arranged parallel to the optical substrate 100 in order of height; the transmission diffraction grating assembly 105 is disposed in the common optical path area of ​​the first optical path layer 203, the second optical path layer 204, the third optical path layer 205, and the fourth optical path layer 206, so that the light beam is focused in four optical paths. When propagating within the optical path layer, the beam can pass through the transmission diffraction grating assembly 105; the mirror group is configured to guide the beam back in each optical path layer so that the beam passes through the transmission diffraction grating assembly 105 twice in each optical path layer; the first height conversion assembly 108 is configured to transfer the beam from the first optical path layer 203 to the fourth optical path layer 206, and to transfer the beam from the third optical path layer 205 to the second optical path layer 204; the second height conversion assembly 109 is configured to transfer the beam from the fourth optical path layer 206 to the third optical path layer 205.

[0021] It should be noted that the optical substrate 100 refers to the platform used to support and fix all optical components in the stacked laser pulse compression device; as the mechanical reference plane of the entire device, it defines the height reference and positional relationship of each optical component and ensures that the relative positions of each optical path layer in space are precisely controllable. The optical substrate 100 can be made of metal materials (such as aluminum alloy, stainless steel) or granite, which have good thermal and mechanical stability, to suppress the influence of environmental vibration and temperature changes on optical path alignment.

[0022] It should be noted that the present invention forms four height optical path layers by stacking and connecting two complete four-pass compression units in series along the height direction, so that the light beam propagates sequentially through the first, fourth, third and second optical path layers, passing through the transmission diffraction grating assembly 105 twice in each layer, for a total of eight light passes; by means of the first height conversion assembly 108, which simultaneously undertakes two inter-layer transitions, and achieves four-layer eight-pass closure with only two cross-layer elements, thereby doubling the dispersion without significantly increasing the lateral footprint, while reducing independent adjustable elements, reducing alignment difficulty, suppressing cumulative wavefront error, and improving assembly consistency and mass production feasibility by solidifying key angular relationships with integral components, providing an engineered terminal compression solution for compact CPA systems and mobile platform integration.

[0023] In one embodiment, the reflector group includes a common reflector, which includes a first common reflector 104, a second common reflector 106, and a third common reflector 107. The first common reflector 104, the second common reflector 106, and the third common reflector 107 penetrate the first optical path layer 203, the second optical path layer 204, the third optical path layer 205, and the fourth optical path layer 206 along a direction perpendicular to the optical substrate 100. The reflective surface of the second common reflector 106 forms a 90° angle with the reflective surface of the third common reflector 107. In one embodiment, the reflector group further includes a layered reflector, which includes a first layered reflector 102 and a second layered reflector 103. The first layered reflector 102 is disposed on the second optical path layer 204 and is used to guide the light beam after two grating light transmissions in the second optical path layer 204 to the light outlet 110. The second layered reflector 103 is disposed at a height position between the third optical path layer 205 and the fourth optical path layer 206 and is a shared reflector for the third optical path layer 205 and the fourth optical path layer 206. It is used to cooperate with the shared reflector to complete the light beam reflection in the third optical path layer 205 and the fourth optical path layer 206 respectively.

[0024] It should be noted that the core of this mirror group configuration lies in achieving independent reflection and closure of four optical paths with the fewest possible optical elements through the functional division of common mirrors and layered mirrors. Specifically, the first common mirror 104, the second common mirror 106, and the third common mirror 107 penetrate the four optical path layers, allowing the beams of each layer to reuse the same set of reflection references. The second common mirror 106 and the third common mirror 107 maintain a 90° angle, which can be achieved by a one-time solidification process using an integral prism, fundamentally avoiding the accumulated angle error and adjustment cost caused by aligning multiple independent mirrors one by one. The first layered mirror 102 only serves to guide the output of the second optical path layer 204, while the second layered mirror 103 is shared by the third optical path layer 205 and the fourth optical path layer 206, further reducing the number of cross-layer components. Overall, this configuration allows the eight-stage grating to complete all reflections and interlayer connections with only a very small number of reflective surfaces. This ensures spatial reuse and height avoidance of the optical paths of each layer in the top-view projection, and significantly reduces the alignment complexity of the multi-stage compression system caused by the excessive number of reflectors. This is beneficial for the efficient assembly and long-term stable operation of the compressor.

[0025] In one embodiment, the light inlet 101 is connected to the first optical path layer 203 and is used to guide the incident light beam into the first optical path layer 203; the light outlet 110 is connected to the second optical path layer 204 and is used to output the compressed pulse after multiple transmission gratings have been completed; the light inlet 101 and the light outlet 110 are located on the same side or opposite side of the device, and spatial separation is achieved by height difference, lateral offset or angular offset.

[0026] It should be noted that the light inlet 101 and the light outlet 110 are merely the entrance and exit positions of the main optical path, not dedicated interfaces. Their entrance and exit directions are unrestricted; any direction that does not obstruct the main optical path can be used as the entrance or exit direction. The light inlet 101 and the light outlet 110 can be located on the same side of the device, and they can be in close proximity in a top-view projection, but staggered in height or lateral direction, thus avoiding complete overlap of the input and output beams. If necessary, the output beam can also be extracted from the side or another side using components such as a small-angle exit mirror, wedge, or polarizing beam splitter.

[0027] It should be noted that the configuration of the light inlet 101 and the light outlet 110 utilizes the inherent layering characteristics of the stacked structure, allowing the input beam and the output beam to naturally propagate on different optical path layers, thus avoiding beam interference without the need for additional isolation components. At the same time, the light inlet 101 and the light outlet 110 can be located on the same side or opposite side of the device, and can be flexibly adapted to different system layout requirements through height difference, lateral offset, or angular offset, thereby facilitating the integration and docking of the compressor with the preamplifier and the subsequent optical path, and improving the engineering adaptability and layout flexibility of the device.

[0028] In one embodiment, a first height conversion component 108 is disposed between a first optical path layer 203 and a fourth optical path layer 206, and between a third optical path layer 205 and a second optical path layer 204. The first optical path layer 203 and the fourth optical path layer 206 form a first group of four-pass compression units by multiplexing the first height conversion component 108, and the third optical path layer 205 and the second optical path layer 204 form a second group of four-pass compression units by multiplexing the first height conversion component 108. A second height conversion component 109 is connected between the fourth optical path layer 206 and the third optical path layer 205, so that the first group of four-pass compression units and the second group of four-pass compression units are connected in series along the optical path, so that the light beam propagates sequentially through the first optical path layer 203, the fourth optical path layer 206, the third optical path layer 205 and the second optical path layer 204, and passes through the transmission diffraction grating component 105 twice in each optical path layer, for a total of eight times.

[0029] It should be noted that, through the reuse of the first height conversion component 108, this application enables the same element to simultaneously handle the interlayer transitions between the first optical path layer 203 and the fourth optical path layer 206, and between the third optical path layer 205 and the second optical path layer 204. In conjunction with the second height conversion component 109, the fourth optical path layer 206 and the third optical path layer 205 are connected. With only two cross-layer elements, two complete four-pass compression units are connected in series along the optical path to form a four-layer eight-pass structure. The beam propagates strictly through the first, fourth, third, and second optical path layers in sequence, passing through the same transmission diffraction grating component 105 a total of eight times. This multiplexing design reduces the required cross-layer prisms from three to two, compressing the number of elements and space occupation to the maximum extent while ensuring the complete closure of the optical path topology. At the same time, the determined interlayer propagation order allows the dispersion contribution of each light transmission to accumulate in the same direction, avoiding the problem of inconsistent dispersion compensation directions in complex optical paths, and significantly reducing the design difficulty and debugging complexity of the multi-pass compression system.

[0030] In one implementation, see Figure 2 The first height conversion component 108 and the second height conversion component 109 are height conversion prisms. Each height conversion prism includes a first mirror 301 and a second mirror 302. The angle between the reflecting surfaces of the first mirror 301 and the second mirror 302 is set to a non-zero angle, and the line connecting the lower vertex 303 of the first mirror and the upper vertex 304 of the second mirror is perpendicular to the optical substrate 100. The first mirror 301 receives the light beam and reflects it to the second mirror 302. The second mirror 302 receives the light beam from the first mirror 301, reflects it a second time, and outputs it, so that the light beam utilizes the reflection characteristics of the first mirror 301 and the second mirror 302 to achieve optical path layer conversion in the first optical path layer 203, the fourth optical path layer 206, the third optical path layer 205, and the second optical path layer 204. The non-zero angle includes, but is not limited to, a 90-degree angle.

[0031] The mid-angle plane of the included angle of the reflective surface is parallel to the optical substrate 100. The first optical path layer 203 and the fourth optical path layer 206 are symmetrical about the mid-angle plane, and the second optical path layer 204 and the third optical path layer 205 are symmetrical about the mid-angle plane.

[0032] The first mirror 301 and the second mirror 302 form a reflective angle, and there is a ridge ridge at the junction of the first mirror 301 and the second mirror 302; the median plane of this reflective angle refers to the plane formed by the angle bisector of the reflective angle and the ridge ridge.

[0033] The reflection mode of the height-converting prism includes any one of total internal reflection, metallic film reflection, or dielectric high-reflection film reflection; the optical material of the height-converting prism includes any one of fused silica, low-dispersion glass, and crystal.

[0034] In another embodiment, the second height conversion component 109 is a height conversion prism, which includes a reflective surface angle, and the median plane of the reflective surface angle is parallel to the optical substrate 100; the fourth optical path layer 206 and the third optical path layer 205 are symmetrical about the median plane of the angle.

[0035] It should be noted that this height-converting prism utilizes the non-zero angle between the internal first mirror 301 and the second mirror 302 to achieve height conversion of the beam between different optical path layers through two reflections. The median plane of the angle between the reflecting surfaces is configured to be parallel to the optical substrate 100, making the first optical path layer 203 and the fourth optical path layer 206 symmetrical about this median plane, and the second optical path layer 204 and the third optical path layer 205 also symmetrical about this median plane. Thus, the same prism can simultaneously handle the transition between the first and fourth layers, and between the third and second layers. This is the structural basis for the first height-converting component 108 to achieve "one-time reuse, two-time layer replacement". At the same time, the angular relationship between the two reflecting surfaces is solidified in one step during prism processing, eliminating the need for on-site calibration of the relative angles of multiple independent reflecting mirrors. This eliminates the source of accumulated alignment errors and ensures the consistency and repeatability of the angular relationship in mass production, which is beneficial for the efficient assembly and stable operation of the compressor.

[0036] In one embodiment, the transmission diffraction grating assembly 105 is configured as a transmission grating of any one of a volume holographic grating, a surface relief grating, or a multilayer dielectric film grating.

[0037] It should be noted that the transmission diffraction grating assembly 105 can be selected from any one of volume holographic grating, surface relief grating, or multilayer dielectric film grating according to specific application requirements. Different types of gratings have their own advantages in terms of diffraction efficiency, damage threshold, spectral bandwidth, and polarization characteristics, enabling the device to flexibly adapt to compression requirements of different working conditions, from low-power wide spectrum to high-power narrow pulse. At the same time, regardless of the type of grating selected, it works under the four-layer eight-path stacked optical path framework of this invention. Changes in the form of the grating itself do not affect the universality of the main optical path topology and the effectiveness of the multiplexing structure. Thus, while ensuring that the core architecture of the compressor remains unchanged, the selection space of materials and processes is expanded, and the applicability and engineering flexibility of the device are improved.

[0038] Example 2

[0039] This invention provides a compression optical path for a stacked laser pulse compression device, see [link to documentation]. Figure 3The four optical path layers in the diagram, in the order of propagation, function as follows: the first optical path layer 203 is the input layer, completing the first and second grating light transmissions; the fourth optical path layer 206 is the upper transmission layer, completing the third and fourth transmissions; the third optical path layer 205 is the intermediate transmission layer, completing the fifth and sixth transmissions; and the second optical path layer 204 is the output layer, completing the seventh and eighth transmissions and outputting the light through the output port 110. Label 108 represents the first height conversion component; 109 represents the second height conversion component; and 203 to 206 represent the first to fourth optical path layers, respectively. A specific beam propagation process of a stacked laser pulse compression device is described below. Figure 4 Specifically: First, the incident chirped pulse beam enters the first optical path layer 203 through the light inlet 101, then passes through the transmission diffraction grating assembly 105. With the cooperation of components such as the first common mirror 104, the second common mirror 106, and the third common mirror 107, it completes its refracted propagation within the first optical path layer 203, thus completing the first and second passes through the transmission diffraction grating assembly 105. The optical path sequence within the first optical path layer 203 is: light inlet 101, first common mirror 104, transmission diffraction grating assembly 105, second common mirror 106, third common mirror 107, transmission diffraction grating assembly 105, and then guides to the first height conversion assembly 108.

[0040] Secondly, after two grating light transmissions are completed within the first optical path layer 203, the light beam is transferred from the first optical path layer 203 to the fourth optical path layer 206 via the first height transformation component 108. Since the fourth optical path layer 206 and the first optical path layer 203 are at different spatial heights, they can reuse similar or identical propagation areas in the top-view projection without actual spatial overlap.

[0041] Furthermore, after the light beam is introduced into the fourth optical path layer 206 by the first height conversion component 108, it passes through the transmission diffraction grating component 105 for the third time, then is reflected back sequentially by the third common mirror 107 and the second common mirror 106, passes through the transmission diffraction grating component 105 for the fourth time, and is then redirected by the second layered mirror 103 and guided to the second height conversion component 109. The optical path sequence within the fourth optical path layer 206 is: first height conversion component 108, transmission diffraction grating component 105, third common mirror 107, second common mirror 106, transmission diffraction grating component 105, first common mirror 104, second layered mirror 103, and second height conversion component 109. The first optical path layer 203 and the fourth optical path layer 206 together constitute the first complete four-pass compression unit.

[0042] Subsequently, the beam is transferred from the fourth optical path layer 206 to the third optical path layer 205 via the second height conversion component 109. Within the third optical path layer 205, it is first redirected by the second layered reflector 103 and the first common reflector 104, then passes through the transmission diffraction grating component 105 for the fifth time. It is then reflected back sequentially by the second common reflector 106 and the third common reflector 107, and passes through the transmission diffraction grating component 105 for the sixth time. The optical path sequence within the third optical path layer 205 is: second height conversion component 109, second layered reflector 103, first common reflector 104, transmission diffraction grating component 105, second common reflector 106, third common reflector 107, transmission diffraction grating component 105, and then guided to the first height conversion component 108.

[0043] Then, after two grating light transmissions are completed within the third optical path layer 205, the beam is again transferred from the third optical path layer 205 to the second optical path layer 204 via the first height conversion component 108. This multiplexing method enables the first height conversion component 108 to perform two inter-layer transfer functions: from the first layer to the fourth layer and from the third layer to the second layer.

[0044] Finally, after being guided into the second optical path layer 204 by the first height conversion component 108, the beam passes through the transmission diffraction grating component 105 for the seventh time, then is reflected back sequentially by the third common mirror 107 and the second common mirror 106, passes through the transmission diffraction grating component 105 for the eighth time, and then is redirected by the first common mirror 104 and the first layered mirror 102, finally exiting from the light outlet 110. The optical path sequence within the second optical path layer 204 is: first height conversion component 108, transmission diffraction grating component 105, third common mirror 107, second common mirror 106, transmission diffraction grating component 105, first common mirror 104, first layered mirror 102, light outlet 110. Through the cascading of the above two sets of four-pass compression units, the beam passes through the transmission diffraction grating component 105 a total of eight times in one compression cycle.

[0045] It should be noted that in the transmission grating compression topology used in this device, four passes constitute a complete compression unit, and a complete four-pass compression unit requires two optical path layers with staggered heights to function. This invention does not simply stack any number of layers; instead, it connects two complete four-pass compression units in series, allowing them to share the same transmission diffraction grating assembly 105 and arrange them in layers along the height direction. The first set of four-pass compression units consists of a first optical path layer 203 and a fourth optical path layer 206, connected by a first height conversion assembly 108; the second set of four-pass compression units consists of a third optical path layer 205 and a second optical path layer 204, also connected by a first height conversion assembly 108. A second height conversion assembly 109 is used to transfer the fourth optical path layer 206 to the third optical path layer 205, allowing the two sets of four-pass compression units to be continuously connected in series to form an eight-pass transmission. In this structure, the dispersion contribution generated by each pass through the transmission diffraction grating assembly 105 should be configured to accumulate in the same direction. Specifically, this can be achieved through a combination of designs involving grating parallelism, incident angle, diffraction order, foldback direction, and interlayer transition direction.

[0046] Furthermore, the height-converting prism assembly is used as a beam path switching element, rather than a grism-type composite dispersive element. Figure 3 and Figure 4In this configuration, the first height conversion component 108 and the second height conversion component 109 can specifically be height conversion prisms. The first height conversion component 108 is used for interlayer transitions between the first optical path layer 203 and the fourth optical path layer 206, and between the third optical path layer 205 and the second optical path layer 204. The second height conversion component 109 is used for height conversion between the fourth optical path layer 206 and the third optical path layer 205. Through the cooperation of the first height conversion component 108 and the second height conversion component 109, two complete four-pass compression units can be continuously connected in series between the four optical path layers. The reason why the first height conversion component 108 can simultaneously handle two interlayer transitions is that this device deliberately adopts the propagation sequence of the first optical path layer 203, the fourth optical path layer 206, the third optical path layer 205, and the second optical path layer 204, so that the two transition paths (from the first optical path layer 203 to the fourth optical path layer 206, and from the third optical path layer 205 to the second optical path layer 204) are in similar or the same lateral region in the top view projection; when the light beam passes through the first height conversion component 108 twice, it is at a different height and there will be no spatial overlap, so the lateral position can be shared. Specifically, the ridge (roof ridge, i.e. its reflection symmetry centerline) of the first height transformation component 108 is located at the center height of the first optical path layer 203 and the fourth optical path layer 206; the four optical path layers are symmetrically arranged about this center height (the second optical path layer 204 and the third optical path layer 205 are also symmetrical about this centerline). Therefore, the beam can be reflected and flipped once with this ridge as the centerline of symmetry, and the two sets of interlayer transitions from the first optical path layer 203 to the fourth optical path layer 206 and from the third optical path layer 205 to the second optical path layer 204 can be completed simultaneously by the same prism. This design reduces the number of cross-layer prisms from three to two, improves the utilization rate of components (devices) and realizes the compactness of the laser pulse compression device.

[0047] The laser pulse compression device of this application is based on a standard four-pass transmission grating compression optical path. By using a height-conversion prism assembly, the original two-layer four-pass optical path is expanded into a four-layer eight-pass optical path, so that the beam passes through the transmission diffraction grating assembly 105 a total of eight times in one compression cycle, achieving the following objectives: 1. Increase the number of light passes and the effective dispersion of the transmission grating assembly without significantly increasing the lateral area occupied; 2. By using a layered arrangement in the height direction, beams of different orders can reuse optical path areas in the top-view projection and avoid each other in the actual height. 3. Cross-layer transitions are achieved through prisms or equivalent height transformation reflective components, reducing the problems of excessive number of reflectors, complex adjustment, and beam cross-blocking in planar folded structures; 4. Maintain the controllability of the dispersion design of the transmission grating compressor so that the dispersion contributions generated by each pass through the grating accumulate in the same direction; 5. Allows the input and output optical paths to be spatially separable (e.g., staggered on the same side), facilitating integration with the preamplifier, isolator, diagnostic optical path, and post-focusing system of the CPA laser system; 6. By utilizing the same transmission diffraction grating assembly 105 shared by eight passes, a four-layer shared reflector group, and an integrated height conversion prism, the on-site debugging difficulty of multi-pass grating multiplexing is reduced, and the assembly repeatability and consistency of the compressor in industrial mass production are improved.

[0048] Example 3

[0049] This embodiment provides several other implementation schemes of the aforementioned stacked laser pulse compression device while maintaining its basic optical path topology. In the transmission grating compression optical path used in this invention, four passes constitute a complete compression unit, and a complete four-pass compression unit requires two optical path layers with staggered heights to function. Therefore, this invention is not a multi-layer optical path structure with an arbitrary number of layers, but rather stacks and connects two sets of complete four-pass compression units in the height direction to form four optical path layers, and allows the beam to pass through the transmission diffraction grating assembly 105 a total of eight times in one compression cycle. The following schemes are all based on the premise of not changing the basic topology of four optical path layers, two sets of four-pass compression units connected in series, and a total of eight passes through the transmission diffraction grating assembly 105.

[0050] Adjustment of the spacing between optical path layers: The height difference between each optical path layer can be adjusted according to the beam aperture, optical component size, installation space, and mechanical structure, but the number of optical path layers remains unchanged at four. The height difference between adjacent optical path layers should be greater than the effective beam diameter and the necessary mechanical margin to avoid spatial overlap, beam cutoff, or component obstruction between beams from different optical path layers. The center heights of the first height conversion component 108 and the second height conversion component 109 can also be adjusted synchronously according to the above factors.

[0051] Mirroring and Reversing the Optical Path: Without changing the basic four-layer eight-pass topology, the optical path can be arranged in a horizontal or vertical mirror configuration; the input and output ends can also be interchanged depending on the installation direction. The equivalent transformation structure should meet the following conditions: each complete four-pass compression unit is completed by the cooperation of two optical path layers; the two four-pass compression units are connected in series in the height direction; the beam passes through the transmission diffraction grating assembly 105 a total of eight times; the dispersion contribution generated by each grating passage remains in the same direction and accumulates.

[0052] Adjustment of reflector angles and spacing: The angles of some of the reflecting mirrors can be adjusted according to the optical path closure conditions, beam aperture, and installation space. Specifically, the reflecting surfaces of the second common reflector 106 and the third common reflector 107 should maintain a 90° perpendicular relationship. This 90° relationship can be achieved using two independent reflectors, or by using an integral right-angle prism or a roof prism for one-time installation. Regardless of the method used, this 90° relationship will not change due to adjustments in the overall installation angle. The incident angle of the beam on the transmission diffraction grating assembly 105 can be any value that achieves the compression function, and is not limited to a specific angle.

[0053] The spacing between the mirror groups can be of any length and is not limited to a specific value. Specifically, the spacing between the second common mirror 106 and the third common mirror 107 determines the effective length of the transmission diffraction grating assembly 105 and the actual position of the first height transformation assembly 108. The distance along the optical path between the transmission diffraction grating assembly 105 and the second and third common mirrors 106 and 107 determines the equivalent grating spacing and group delay dispersion of each beam path, thereby determining the total dispersion compensation. Any value of any of the above spacings is within the scope of protection of this invention, but the above adjustments should not change the fundamental relationship of two passes through the transmission diffraction grating assembly 105 within each optical path layer.

[0054] Alternatives to the height conversion elements: The first height conversion component 108 and the second height conversion component 109 are not limited to the height conversion prism form in the foregoing embodiments. They can also be replaced by right-angle prisms, roof prisms, pentaprisms, pyramidal prisms, hollow reflective prisms, or height conversion reflector groups composed of two or more plane mirrors. The above alternative structures should maintain the original function, that is, realize the height switching between the four optical paths, and not change the topology of the four-layer eight-path main optical path. When using solid prisms, the group delay dispersion, third-order dispersion, nonlinear phase, and thermal effects introduced by the prism material should be considered. In high-power or wide-spectrum applications, low-dispersion materials, coated reflective structures, or hollow reflective prism structures can be used to reduce the dispersion of additional materials. The height conversion prism components can use optical materials suitable for ultrashort pulse transmission, such as fused silica, low-dispersion glass, or crystals; their reflection mode can be any one of total internal reflection, metallic film reflection, or dielectric high-reflection film reflection.

[0055] Alternatives to the catadioptric reflector: Within the same optical path layer, the catadioptric reflector is not limited to a plane mirror; it can be implemented using components with equivalent reflection capabilities, such as roof mirrors, corner cube mirrors, and reflecting prisms. The specific structure of the catadioptric reflector can be selected based on beam aperture, offset, installation space, and adjustment method.

[0056] Alternative input / output method: The input port 101 and output port 110 are merely the incident and exit positions of the main optical path; their incident and exit directions are unrestricted and can be incident or exited from any direction that does not obstruct the main optical path. After completing eight grating passes, the output beam can be extracted through a small-angle mirror, wedge, polarizing beam splitter, thin-film reflector, or other exit coupling elements; the input beam can also be introduced through the aforementioned coupling elements. This change in input / output method should not alter the four-layer, eight-pass structure of the main compression optical path.

[0057] Alternatives to beam separation: Different order beams can be separated mainly by height difference, or lateral offset, angular offset, or a combination of height difference and lateral offset can be introduced to avoid spatial overlap, mechanical obstruction, or light cut-off at the edge of components between different order beams.

[0058] The above description details three embodiments of the present invention, but these are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent variations made within the scope of the claims of this invention should fall within the scope of the claims.

Claims

1. A stacked laser pulse compression device, characterized in that, The device includes an optical substrate (100), a transmission diffraction grating assembly (105), a first height conversion assembly (108), a second height conversion assembly (109), and a mirror assembly; The first optical path layer (203), the second optical path layer (204), the third optical path layer (205) and the fourth optical path layer (206) are arranged in sequence according to their height and parallel to the optical substrate (100). The transmission diffraction grating assembly (105) is disposed in the common optical path area of ​​the first optical path layer (203), the second optical path layer (204), the third optical path layer (205) and the fourth optical path layer (206) so that the beam can pass through the transmission diffraction grating assembly (105) when it propagates in the four optical path layers. The mirror assembly is configured to guide the beam back in each optical path layer so that the beam passes through the transmission diffraction grating assembly (105) twice in each optical path layer. The first height conversion component (108) is configured to transfer the beam from the first optical path layer (203) to the fourth optical path layer (206), and to transfer the beam from the third optical path layer (205) to the second optical path layer (204). The second height conversion component (109) is configured to transfer the beam from the fourth optical path layer (206) to the third optical path layer (205).

2. The stacked laser pulse compression device according to claim 1, characterized in that, The device further includes an inlet (101) and an outlet (110); the inlet (101) is connected to the first optical path layer (203) and is used to guide the incident light beam into the first optical path layer (203); the outlet (110) is connected to the second optical path layer (204) and is used to output the compressed pulse after multiple transmission gratings are completed; the inlet (101) and the outlet (110) are located on the same side of the device and are spatially separated by height difference, lateral offset or angular offset.

3. The stacked laser pulse compression device according to claim 1, characterized in that, The mirror assembly includes a common mirror, which includes a first common mirror (104), a second common mirror (106), and a third common mirror (107). The first common reflector (104), the second common reflector (106), and the third common reflector (107) penetrate the first optical path layer (203), the second optical path layer (204), the third optical path layer (205), and the fourth optical path layer (206) in a direction perpendicular to the optical substrate (100). The reflecting surface of the second common reflector (106) forms a 90° angle with the reflecting surface of the third common reflector (107).

4. The stacked laser pulse compression device according to claim 3, characterized in that, The reflector group also includes a layered reflector, which includes a first layered reflector (102) and a second layered reflector (103). The first layered reflector (102) is located on the second optical path layer (204) and is used to guide the light beam after two grating light transmissions in the second optical path layer (204) to the light outlet (110). The second layered reflector (103) is located at a height between the third optical path layer (205) and the fourth optical path layer (206) and is a shared reflector for the third optical path layer (205) and the fourth optical path layer (206). It is used to cooperate with the shared reflector to complete the light beam reflection in the third optical path layer (205) and the fourth optical path layer (206) respectively.

5. The stacked laser pulse compression device according to claim 1, characterized in that, The first height conversion component (108) is disposed between the first optical path layer (203) and the fourth optical path layer (206) and between the third optical path layer (205) and the second optical path layer (204); The first optical path layer (203) and the fourth optical path layer (206) form a first group of four-pass compression units by multiplexing the first height conversion component (108), and the third optical path layer (205) and the second optical path layer (204) form a second group of four-pass compression units by multiplexing the first height conversion component (108). The second height conversion component (109) is connected between the fourth optical path layer (206) and the third optical path layer (205) so that the first group of four-pass compression units and the second group of four-pass compression units are connected in series along the optical path, so that the beam propagates sequentially through the first optical path layer (203), the fourth optical path layer (206), the third optical path layer (205) and the second optical path layer (204), and passes through the transmission diffraction grating component (105) twice in each optical path layer, for a total of eight times.

6. The stacked laser pulse compression device according to claim 1, characterized in that, The first height conversion component (108) and the second height conversion component (109) are height conversion mirror groups. The height conversion mirror group includes a first mirror (301) and a second mirror (302). The first mirror (301) and the second mirror (302) are provided with a non-zero included angle, and the connecting line between the lower vertex (303) of the first mirror and the upper vertex (304) of the second mirror is perpendicular to the optical substrate (100). The first mirror (301) is used to receive the light beam and reflect it to the second mirror (302). The second mirror (302) is used to receive the light beam from the first mirror (301), reflect the light beam a second time, and output it, so that the light beam can realize optical path layer conversion in the first optical path layer (203), the fourth optical path layer (206), the third optical path layer (205), and the second optical path layer (204) by utilizing the reflection characteristics of the first mirror (301) and the second mirror (302).

7. The stacked laser pulse compression device according to claim 1, characterized in that, The first height conversion component (108) is a height conversion prism. The height conversion prism has two intersecting reflective surfaces, and an angle is formed between the two reflective surfaces. The median plane of the angle is set to be parallel to the optical substrate (100). The first optical path layer (203) and the fourth optical path layer (206) are symmetrical about the median plane of the angle, and the second optical path layer (204) and the third optical path layer (205) are symmetrical about the median plane of the angle. The second height conversion component (109) is a height conversion prism, and the mid-angle plane corresponding to the included angle of the reflective surface in the height conversion prism is set to be parallel to the optical substrate (100); the fourth optical path layer (206) and the third optical path layer (205) are set to be symmetrical about the mid-angle plane.

8. A stacked laser pulse compression device according to claim 7, characterized in that, The reflection mode of the height-converting prism includes any one of total internal reflection, metal film reflection, or dielectric high-reflection film reflection; The transmission diffraction grating assembly (105) is configured as a transmission grating of any one of a volume holographic grating, a surface relief grating, or a multilayer dielectric film grating.

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