Optical device for increasing spectral bandwidth and shortening ultrashort pulses

Abstract

Optical device, wherein it is possible to generate the required bandwidth increase by self-phase modulation (SPM) in a compact configuration, wherein the self-focusing generated here by the Kerr lens effect does not cause a drop in beam quality and does not impair the shaping optics due to high power density. A multi-pass cell consisting of mirror devices is used. A nonlinear medium with negligible absorption is arranged in the multi-pass cell to generate the self-phase modulation. A laser beam is transformed into a defined astigmatic beam by means of the shaping optics and coupled into the multi-pass cell, wherein the laser beam is reflected back and forth between the mirror devices and passes through the nonlinear medium multiple times. The mirrors of the mirror devices are designed curved and arranged in such a way that the beam has multiple waists within the multi-pass cell, wherein the waists are at different z positions in the xz plane and the yz plane, wherein the x-y-z coordinates form a rectangular xyz coordinate system.

Description

Background Technology

[0001] The use of ultrashort pulse lasers for material processing is becoming increasingly important for precise and flexible manufacturing methods. High precision is primarily based on the fact that the laser pulse is shorter than the characteristic time constant of the thermal interaction between the laser pulse and the material being processed. Generally, the shorter the pulse, the more precise the processing.

[0002] Ultrashort pulse lasers used for industrial material processing consist of an oscillator amplifier unit. The pulse length of the oscillator is determined by the bandwidth of the laser medium used. Therefore, the typical pulse duration of a mode-locked Yb:YAG oscillator is 700 fs. The oscillator amplifier unit is used to generate pulse energy relevant to material processing. Depending on the bandwidth of the amplification medium, the bandwidth of the amplified pulse decreases due to the narrowing of the gain, thereby lengthening the amplified pulse.

[0003] The nonlinear process of self-phase modulation can be used to increase bandwidth. Of course, self-phase modulation is associated with spatial phase modulation, such as the Kerr lensing effect. The Kerr lensing effect can lead to catastrophic self-focusing and an unacceptable reduction in beam quality.

[0004] Concurrent beams are primarily used in materials processing. Under free propagation, a concurrent beam exhibits a circular power density distribution in each plane perpendicular to the propagation direction. The beam waists of the concurrent beams are of equal size and located in the same position on both mutually perpendicular planes. In this case, the power density is inversely proportional to the square of the beam diameter. In stable and compact optical structures, this results in very high power densities at the focal point, mirror, or lens. Excessively high power densities can damage optical devices such as lenses and mirrors.

[0005] DE 10 2014 007 159A1 describes a method and apparatus for spectral broadening of laser pulses for nonlinear pulse compression.

[0006] A laser pulse is coupled into an optical device in which the laser pulse propagates alternately through at least one segment comprising at least one medium having nonlinear optical properties, wherein the laser pulse acquires a nonlinear phase through self-phase modulation, and wherein a nonlinear phase is substantially not generated through self-phase modulation.

[0007] DE 10 2015 005 257 A1 describes an optical device for improving beam quality and enhancing the intensity distribution of a laser beam. The beam is focused using one or more spherical and / or cylindrical components, such as lenses and / or mirrors. At least two apertures are used in a row along the beam in the focusing region of the components, wherein the opening shape and size of the apertures are determined by the beam cross-section at corresponding axial positions of the apertures.

[0008] The publication BRONS, Jonathan et al., "Efficient, high-power, all-bulk spectrabroadening in a quasi-waveguide," 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO / Europe-EQEC), IEEE, 2017, pp. 1-1, discusses efficient, high-power, and spectral broadening of ultrashort pulses in quasi-waveguides. Summary of the Invention

[0009] The objective of this invention is to provide an optical device that enables a determined increase in bandwidth through self-phase modulation (SPM) in a compact configuration.

[0010] The objective is achieved by a device having the features of claim 1. Advantageous designs of the device are derived from the dependent claims.

[0011] According to the present invention, an optical device for increasing spectral bandwidth to shorten ultrashort pulses through nonlinear self-phase modulation utilizes a multi-channel unit and a nonlinear medium. The nonlinear medium is disposed within the multi-channel unit, and a laser beam with an ultrashort pulse passes through the nonlinear medium multiple times. The laser beam is coupled into the multi-channel unit via a shaping optics device, wherein the shaping optics device shapes the laser beam into an imaged scattered beam and couples it into the multi-channel unit.

[0012] With this device, it is possible to generate a determined increase in bandwidth by means of self-phase modulation (SPM) in a compact configuration, where self-focusing caused by the Kerr lens effect does not cause a decrease in beam quality and does not damage the shaping optics by high power density.

[0013] The preferred multi-channel unit is the Heriot multi-channel unit.

[0014] In an advantageous embodiment, the multi-channel unit includes three cylindrical mirrors. The three cylindrical mirrors are designed and configured such that their curvature lies in a common xz plane and their focal planes lie in a common focal plane. The beam is designed and configured by a shaping optics such that it is converted into a beam collimated in the yz plane and has a focal point in the xz plane, and such that the nonlinear medium is positioned in or near the focal plane.

[0015] The x, y, and z coordinates are in a rectangular coordinate system, where the z coordinate is parallel to the propagation direction, and the x and y coordinates are perpendicular to each other and perpendicular to the propagation direction.

[0016] In another advantageous embodiment, the multi-channel unit comprises three spherical mirrors. The three spherical mirrors are designed and configured such that they form a white multi-channel unit and have a common focal plane. The shaping optics are designed and configured to convert the beam into an image-scattered beam, which is collimated in the yz plane and has a focal point in the xz plane, or collimated in the xz plane and has a focal point in the yz plane. A nonlinear medium is disposed in or near the focal plane. The x, y, and z coordinates form a Cartesian xyz coordinate system, where the z-coordinate is parallel to the beam propagation direction.

[0017] An optical device is also proposed, whose multi-channel unit consists of two cylindrical mirrors. The two cylindrical mirrors are designed and configured such that their focal lines lie in the xz fold plane and in a common focal plane. The shaping optics are designed and configured to convert a laser beam into an image-scattered beam, which is collimated in the xz plane and has a focal point in the yz plane. A nonlinear medium is placed in or near the focal plane. The mentioned x, y, and z coordinates form a Cartesian xyz coordinate system.

[0018] In another optical device of the present invention, the multi-channel unit comprises two mirror arrays, each comprising at least two spherical and concave mirror elements. The spherical mirror elements are identical and concave, and the focal points of the spherical mirror elements lie in a common plane. The shaping optics are designed and configured such that the beam is converted into an image-scattered beam, which is collimated in the yz plane and has a focal point in the xz plane, or collimated in the xz plane and has a focal point in the yz plane. A nonlinear medium is disposed in or near the focal plane, and the z-coordinate is parallel to the beam propagation direction.

[0019] Another advantage is that at least one of the mirrors is provided with a cladding for compensating for dispersion, so that at least one mirror acts as a GDD (group delay dispersion) or GTI (Gires-Tournois interferometer) to compress the pulse.

[0020] It is also proposed that at least one aperture array be used in a multi-channel unit to improve beam quality. The aperture array opening is geometrically matched to the beam cross-section of the corresponding beam passage location. The aperture array is positioned at one or more folding mirrors and / or in and / or near the focal plane.

[0021] The aperture cross-section of at least one aperture array should be 1.3 to 2 times the beam cross-section of the corresponding Gaussian beam.

[0022] To minimize pulse length or match requirements, gratings, prisms, GDD mirrors, and / or GTI mirrors are positioned behind the multichannel unit on the output side along the beam propagation direction, i.e., along the z-direction, to compress or shorten the pulse.

[0023] By also using cylindrical shaping optics, such as cylindrical lenses, cylindrical mirrors, or prisms, the image scattered beam can be reshaped into a single image scattered beam. Attached Figure Description

[0024] Embodiments of the present invention are illustrated in the accompanying drawings.

[0025] Figure 1 A schematic example of a scattered beam is shown.

[0026] Figure 2a The Heriot multichannel unit is shown, in which Figure 2b and 2c Show Figure 2a The two mirrors have the cross-section of the laser beam that hits the corresponding mirror.

[0027] Figure 3a and 3b Another implementation of the multi-channel unit is shown, in Figure 3a The top view is shown in the figure. Figure 3b The middle shows with Figure 3a The associated side views, where Figures 3c and 3e show the beam cross-section of the laser beam at the respective mirrors and Figure 3d The cross-section of the laser beam in the mid-plane is shown.

[0028] Figures 4a to 4d Another embodiment of the device according to the invention is shown, the device having a multi-channel unit comprising three concave curved mirrors with spherical surfaces, wherein Figure 4b and Figure 4d The cross-section of the laser beam at the mirror surface is shown, and Figure 4c The cross-section of the laser beam in the mid-plane is shown.

[0029] Figure 5a and 5e Another embodiment of the device for a concave mirror having two cylindrical surfaces according to the invention is shown, wherein... Figure 5a Showing a top view and Figure 5b The corresponding side view is shown; the cross-section of the laser beam at the two mirrors is shown. Figure 5c and 5e As shown in the middle, Figure 5d The cross-section of the laser beam in the mid-plane is shown.

[0030] Figure 6aA top view of another embodiment of the device having a multi-channel unit according to the present invention is shown. Figure 6b The corresponding side view is shown. The multi-channel unit consists of two mirror arrays, which are constructed from curved spherical mirror elements with identical concave surfaces, and which in turn have a laser beam in... Figure 6c and 6e The beam cross-section on the mirrors of the two mirror arrays and in Figure 6d The beam cross-section in the middle plane, and

[0031] Figure 7b , 7c Figures 7d and 7d show different aperture arrays, which can be used, for example, in the multichannel unit shown in Figure 4, in front of mirror 776, in focal plane 33, and in front of mirrors 777 and 778, respectively. Detailed Implementation

[0032] In the attached diagram, the x, y, and z coordinates illustrate the rectangular xyz coordinate system.

[0033] Figure 1 An example of a single-image scattered beam is shown. The single-image scattered beam propagates in the z-direction. In the xz plane, the beam has a waist dσx0 with a Rayleigh length Z0x. In the yz plane, the beam has a waist dσy0 with a Rayleigh length Z0y. θσx represents the divergence angle in the xz plane, and θσy represents the divergence angle in the yz plane. In the case of a single-image scattered beam, shaping optics can be positioned such that the cross-section of the beam is approximately circular, thereby significantly reducing the power density on the shaping optics without excessively high intensity in the focal plane.

[0034] The core idea of ​​this invention is to use a multi-channel unit, which consists of mirror devices having mirrors 771, 772, 796, 797, 798, 776, 777, 778, 717, 718 or 727, 728 as shown in the figures. A nonlinear medium 66 with negligible absorption is disposed in the multi-channel unit to generate self-phase modulation, wherein a laser beam 1 is converted into a defined single-image scattered beam 11 by means of a shaping optics device 261 and coupled into the multi-channel unit. The laser beam 11 is reflected back and forth between the mirror devices, causing it to pass through the nonlinear medium 66 multiple times, wherein the mirrors are curved and arranged such that the beam has multiple waists within the multi-channel unit. The waists are located in the xz plane and at different z positions in the yz plane.

[0035] In the diagram, Figure 2aA Heriot-Lewis multichannel unit is shown, comprising two spherical mirrors 771 and 772. A beam 1, or laser beam 1, is shaped into a single-image scattered beam 11 using a shaping optics device 261. The single-image scattered beam 11 is coupled into the Heriot-Lewis multichannel unit via an edge mirror 781, i.e., a mirror with a sharp edge. Mirrors 771 and 772 are designed and arranged to cooperate with the shaping optics device 261 to give the beam a varying elliptical cross-section along the propagation direction within the multichannel unit. For example, Figure 2b The cross-section of the beam at mirror 771 is shown, and Figure 2c The beam cross-section at mirror 772 is shown. A medium 66 is disposed within the multichannel unit. Medium 66 exhibits negligible absorption of the beam 11 and serves as a nonlinear medium that induces self-phase modulation at high pulse power densities. An example medium is a quartz glass plate coated on both sides in a manner that resists reflection from the beam 11. The beam from the multichannel unit is coupled out as an output beam 19 using an additional edge mirror 782. The beam spectrum broadens due to the cumulative self-phase modulation from multiple passes through the nonlinear medium.

[0036] The simplest embodiment of the shaping optical device 261 consists of a cylindrical lens with a defined focal length. The focal length should be selected and adjusted so that the focus of the beam is located in the focusing plane, in the focal plane, or near the focal plane 33.

[0037] Dispersion in the medium and air produces different propagation velocities for different wavelengths. This causes an increase in the pulse duration of the beam. The beam pulse can be compressed or shortened by downstream devices consisting of dispersion-shaping optics. To compress the pulse, gratings, mirrors such as GDD mirrors, GTI mirrors, prisms, etc., can be used.

[0038] Advantageously, at least one of mirrors 771 and 772 is a GDD (group delay dispersion) or GTI (Gires-Tournois interferometer) mirror. The dispersion of the mirror is selected such that it compensates for the dispersion caused by the medium and air, and shortens the pulse length caused by the incremental broadening of the beam spectrum after each pass.

[0039] exist Figure 3a and 3b Another implementation scheme is shown here. Figure 3a Showing a top view, and Figure 3bA side view of the multichannel unit is shown. The multichannel unit consists of three cylindrical mirrors 796, 797, and 798. The curvature of the mirrors lies in the xz plane. In the illustrated case, the three mirrors have the same curvature radius. Mirrors 797 and 798 are advantageously positioned vertically relative to each other in the x-direction at the same z-position. Mirror 796 is positioned relative to mirrors 797 and 798 such that the distance is equal to the curvature radius of mirrors 797 and 798. The mirrors thus form a confocal device. The dashed symbol indicates the intermediate plane 33 of the multichannel unit. In this specific case, the intermediate plane 33 is simultaneously the focal plane of mirrors 796, 797, and 798. A nonlinear medium 66 is disposed near the intermediate plane 33. The image scattering beam 11, shaped by a shaping optics device 261, is coupled into the multichannel unit. In the illustrated embodiment, eight beam paths 111, 112, 113, 114, 115, 116, 117, and 118 are formed within the multichannel unit. In principle, beam 1 can have any cross-section. For simplicity, it is assumed that beam 1 has a circular cross-section. The shaping optics 261 is designed and configured such that beam 11 is approximately collimated in the yz focal plane and the waist of the beam entering the xz focal plane is located at the intermediate plane 33. After reflection by mirror 797, the beam is collimated in the xz focal plane, such that the reflected beam 112 becomes a collimated beam with an approximately circular cross-section.

[0040] By properly incident beam 11 and orienting the mirror, 4*N passes (beam paths) can be generated within the cell. Here, N is an integer.

[0041] Beam 112 is focused and reflected by mirror 796 into beam 113 in the xz focal plane. Beam 113 has its focal point in the intermediate plane or focal plane 33. Therefore, the beam has an elliptical beam cross-section in the intermediate plane 33. Beam 113 is reflected by mirror 798 into beam 114 and collimated. Beam 114 has an approximately circular cross-section.

[0042] In this way, the beam is reflected repeatedly and passes through the medium multiple times. Here, the beam cross-section changes from elliptical to circular, and then back to elliptical again. Figure 3c shows the cross-section of the beam at mirror 796. Figure 3d The cross-section of the beam in the intermediate plane 33 is shown. Figure 3e The beam cross-sections at mirrors 797 and 798 are shown. It is evident that the beam has a large and nearly circular cross-section at the mirrors. This helps to avoid damage to the mirrors due to high pulse peak power.

[0043] Advantageously, at least one of mirrors 796, 797, and 798 is a GDD or GTI mirror. The dispersion of the mirror is selected to compensate for the dispersion caused by the medium and air, and to shorten the pulse length caused by the incremental broadening of the beam spectrum after each pass.

[0044] Figure 4a Another embodiment according to the invention is shown. The multichannel unit consists of three spherical and concave mirrors 776, 777, and 778. In the example shown, the three mirrors have the same radius of curvature. Preferably, mirrors 777 and 778 are positioned vertically relative to each other at the same z-position. Mirror 776 is positioned relative to mirrors 777 and 778 such that the distance is equal to the radius of curvature of the mirror. The mirrors thus form a confocal device. The dashed symbol indicates the intermediate plane 33 of the multichannel unit. In this specific case, the intermediate plane is also the focal plane of the mirror. A nonlinear medium 66 is disposed near or within the intermediate plane 33. The image scattering beam 11, shaped by a shaping optics device 261, is coupled into the multichannel unit. In the example shown, eight beam paths 321, 322, 323, 324, 325, 326, 327, and 328 are formed within the multichannel unit. In principle, beam 1 can have any cross-section. For the sake of simplicity, it is assumed that beam 1 has a circular cross-section. The shaping optics 261 is designed and configured such that the beam 11 is approximately collimated in the yz plane and the beam waist in the xz plane is located at the intermediate plane 33. After reflection from mirror 777, the beam is collimated in the xz plane and focused in the yz plane, such that the reflected beam 322 is an image-scattered beam that is approximately parallel in the xz plane and has a beam waist in the intermediate plane in the yz plane, and whose cross-section changes from circular to elliptical and then back to circular during propagation.

[0045] Beam 322 is reflected by mirror 776 as beam 323. Here, the beam is focused in the xz plane and collimated in the yz plane. In the xz plane, beam 323 has a focal point in intermediate plane 33. Therefore, the beam has an elliptical beam cross-section in intermediate plane 33. The elliptical cross-section of beam 323 is perpendicular to the cross-section of beam 322. Beam 323 is reflected by mirror reflection 778 as beam 324. Here, the beam is collimated in the xz plane and focused in the yz plane. In this way, the beam is reflected repeatedly in the xz plane and passes through the medium multiple times. Here, the beam cross-section changes from elliptical to circular and then back to elliptical. Figure 4b The cross-section of the beam at mirror 776 is shown. Figure 4c The cross-section of the beam in the intermediate plane 33 is shown. Figure 4d The beam cross-sections at mirrors 777 and 778 are shown. It is evident that the beam at the mirrors has a large and approximately circular cross-section compared to the focal plane.

[0046] Advantageously, at least one of mirrors 776, 777, and 778 is a GDD or GTI mirror. The dispersion of the mirror is selected such that it compensates for the dispersion caused by the medium and air, and shortens the pulse length caused by the incremental broadening of the beam spectrum after each pass.

[0047] exist Figure 5a and 5b Another implementation scheme is shown here. Figure 5a Showing a top view, and Figure 5b A side view of the multichannel unit is shown. The multichannel unit consists of two cylindrical concave mirrors 717 and 718. The cylindrical axes of the two mirrors are parallel to each other and lie in the xz plane. In the case shown, the two mirrors have the same radius of curvature. Advantageously, mirrors 717 and 718 are confocally arranged. The dashed symbol indicates the intermediate plane 33 of the multichannel unit. In the confocal case, the intermediate plane is also the focal plane of the mirror. A nonlinear medium 66 is disposed near the intermediate plane 33. The image-scattering beam 11, shaped by the shaping optics 261, is coupled into the multichannel unit at a certain angle. Thus, a sawtooth-shaped multichannel is generated between the two cylindrical mirrors. In principle, the beam 1 can have any cross-section. For the sake of simplicity, it is assumed that the beam 1 has a circular cross-section. The shaping optics 261 is therefore designed and arranged such that the beam 11 is approximately collimated in the xz plane and the beam waist of the beam input in the yz plane is located at the intermediate plane 33. After being reflected by mirror 718, the beam is collimated in the yz plane, so that the reflected beam 362 becomes a beam collimated in both planes with an approximately circular cross-section.

[0048] Beam 362 is focused and reflected by mirror 796 in the yz plane to form beam 363. Beam 363 has a focal point in intermediate plane 33 in the yz plane. Therefore, the beam has an elliptical beam cross-section in intermediate plane 33. Beam 113 is reflected by mirror 798 to form beam 364. Here, beam 364 has an approximately circular cross-section.

[0049] In this way, the beam is reflected repeatedly from the two mirrors and passes through the medium multiple times. Here, the beam cross-section changes from elliptical to circular, and then from circular to elliptical again. Figure 5c The cross-section of the beam at mirror 717 is shown. Figure 5d The cross-section of the beam in the intermediate plane 33 is shown. Figure 5e The beam cross-section at mirror 718 is shown. It is evident that the beam has a large and nearly circular cross-section at the mirror. This helps to avoid damage to the mirror due to high pulse peak power.

[0050] A predetermined number of channels can be generated within a multichannel cell by using an appropriate incident angle of the beam.

[0051] Advantageously, at least one of mirrors 796, 797, and 798 is a GDD or GTI mirror. The dispersion of the mirror is selected to compensate for the dispersion caused by the medium and air, and to shorten the pulse length caused by the incremental broadening of the beam spectrum after each pass.

[0052] Figure 6a and 6b Another embodiment according to the present invention is shown. Figure 6a A top view of the multi-channel unit is shown, and Figure 6b A side view is shown. The multichannel unit consists of two mirror arrays 727 and 728. The mirror arrays are formed by identical, concave spherical mirror elements. The spherical mirror elements have the same radius of curvature. The two mirror arrays are positioned relative to each other at a distance equal to the radius of curvature. The mirror arrays thus form a confocal device. The dashed symbol indicates the intermediate plane 33 of the multichannel unit. In this confocal case, the intermediate plane is also the focal plane of the mirror. A nonlinear medium 66 is disposed near the intermediate plane 33. The image-scattered beam 11, shaped by the shaping optics 261, is coupled into the multichannel unit. In the example shown, beam paths 381, 382, ​​383, 384, 385, 386, 387, 388, 389, 390, 391, 392, and 393 are formed within the multichannel unit. For the sake of simplicity, it is assumed that beam 1 has a circular cross-section. The shaping optics 261 is designed and configured such that the beam 11 is approximately collimated in the xz plane and the beam waist of the input beam in the xz plane is located at the intermediate plane 33. After reflection from the first mirror element of the mirror array 728, the beam is collimated in the xz plane and focused in the yz plane, such that the reflected beam 382 is an image-scattered beam that is approximately parallel in the yz plane and has a beam waist in the intermediate plane in the xz plane, and whose cross-section changes from circular to elliptical and then back to circular during propagation.

[0053] Beam 382 is reflected from the first mirror element of mirror array 727 into beam 383. Here, the beam is focused in the yz plane and collimated in the xz plane. In the yz plane, beam 383 has a focal point in intermediate plane 33. Therefore, the beam has an elliptical beam cross-section in intermediate plane 33. The elliptical cross-section of beam 383 is perpendicular to the cross-section of beam 382. Beam 383 is reflected from the second mirror element of mirror array 728 into beam 384. Here, the beam is collimated in the yz plane and focused in the xz plane. In this way, the beam is reflected repeatedly and passes through the medium multiple times. Here, the beam cross-section changes from elliptical to circular and then back to elliptical. Figure 6c The cross-section of the beam at mirror array 717 is shown. Figure 6d The cross-section of the beam in the intermediate plane 33 is shown in the figure. Figure 6eThe cross-section of the beam at mirror array 718 is shown. It is shown that the beam has a large and approximately circular cross-section at the mirror elements.

[0054] It is also advantageous here that at least one mirror array 717 and 718 is a GDD or GTI mirror. The dispersion of the mirrors is selected such that it compensates for the dispersion caused by the medium and air, and shortens the pulse length caused by the incremental broadening of the beam spectrum after each pass.

[0055] It is advantageous for the common-point beam 1 to use a cylindrical lens in the shaping optical device 261, wherein the focal length of the principal lens is equal to the focal length of the mirror and its focal point is located in the focal plane 33.

[0056] To improve beam quality, one or more aperture arrays can be used in a multi-channel unit. Advantageously, the aperture array is used in or near the focal plane 33. The aperture array has openings whose geometry matches the beam cross-section of the corresponding beam passage portion.

[0057] Figure 7b , 7c An example of the aperture array of the white multichannel unit shown in Figure 4 is shown in Figure 7d.

[0058] Figure 7b An example of an aperture array is shown located directly in front of mirror 776 in a plane. The focal plane has apertures 201, 202, 203, 204, and 205. The aperture array also has five apertures 221, 222, 223, 224, and 225. As a rule of thumb, the cross-section of the apertures should be 1.3 to 2 times the cross-section of the corresponding Gaussian beam. Figure 7c and 7d An exemplary arrangement of the openings for the aperture array at focal plane 33 or at mirrors 777 and 778 is shown.

Claims

1. An optical device for increasing spectral bandwidth to shorten ultrashort pulses by nonlinear self-phase modulation, comprising using a multi-channel unit and a nonlinear medium (66), wherein the nonlinear medium (66) is disposed within the multi-channel unit, and a laser beam (1) having an ultrashort pulse passes through the nonlinear medium (66) multiple times, characterized in that, The laser beam (1) is coupled into the multi-channel unit via a shaping optics device (261), wherein the laser beam (1) is shaped into an image scattering beam via the shaping optics device (261) and coupled into the multi-channel unit; the image scattering beam is collimated in a first plane parallel to the beam propagation direction and has a focal point in a second plane parallel to the beam propagation direction, the first plane and the second plane being orthogonal.

2. The optical device according to claim 1, characterized in that, The multi-channel unit is a Heriot multi-channel unit.

3. The optical device according to claim 1, characterized in that, The multichannel unit includes three cylindrical mirrors (796, 797, 798), wherein the three cylindrical mirrors (796, 797, 798) are designed and configured such that their curvatures lie in a common xz plane and their focal planes lie in a common focal plane (33), wherein the shaping optics (261) are designed and configured such that the laser beam (1) is converted into an image scattering beam (11), the image scattering beam (11) being collimated in the yz plane and having a focal point in the xz plane in the focal plane (33), and the nonlinear medium (66) is disposed in or near the focal plane (33), wherein the x, y, z coordinates form a rectangular xyz coordinate system.

4. The optical device according to claim 1, characterized in that, The multichannel unit is composed of three spherical mirrors (776, 777, 778), wherein the three spherical mirrors (776, 777, 778) are designed and configured such that the three spherical mirrors (776, 777, 778) form a white multichannel unit and have a common focal plane (33), wherein the shaping optics (261) are designed and configured such that the laser beam (1) is converted into an image scattering beam (11), the image scattering beam being collimated in the yz plane and having a focal point in the xz plane, or being collimated in the xz plane and having a focal point in the yz plane, wherein the nonlinear medium (66) is disposed in or near the focal plane (33), wherein the x, y, z coordinates form a rectangular xyz coordinate system.

5. The optical device according to claim 1, characterized in that, The multichannel unit consists of two cylindrical mirrors (717, 718), wherein the two cylindrical mirrors (717, 718) are designed and configured such that the focal lines of the two cylindrical mirrors (717, 718) are located in the xz plane and in a common focal plane (33), wherein the shaping optics (261) is designed and configured such that the laser beam (1) is converted into an image scattering beam (11), the image scattering beam being collimated in the xz plane and having a focal point in the yz plane, wherein the nonlinear medium (66) is disposed in or near the focal plane (33), wherein the x, y, z coordinates form a rectangular xyz coordinate system.

6. The optical device according to claim 1, characterized in that, The multichannel unit consists of two mirror arrays (727, 728), each of which consists of at least two concave spherical mirror elements, wherein the concave spherical mirror elements are identical and concave and curved, and the focal points of the concave spherical mirror elements are located in a common focal plane (33), wherein the shaping optics (261) is designed and configured such that the laser beam (1) is converted into an image scattering beam (11), the image scattering beam being collimated in the yz plane and having a focal point in the focal plane (33) in the xz plane, or being collimated in the xz plane and having a focal point in the yz plane in the yz plane, wherein the nonlinear medium (66) is disposed in or near the focal plane (33), wherein the x, y, z coordinates form a rectangular xyz coordinate system.

7. The optical device according to any one of claims 3 to 6, characterized in that, At least one mirror in the multichannel unit is provided with a coating for compensating for dispersion, such that the at least one mirror acts as a GDD or GTI mirror to compress the pulse.

8. The optical device according to any one of claims 3 to 6, characterized in that, At least one aperture array is used in the multi-channel unit to improve beam quality, wherein the opening of the aperture array is geometrically matched to the beam cross-section of the corresponding beam passing through the aperture array, wherein the aperture array is disposed at one or more folding mirrors and / or disposed in and / or near the focal plane (33).

9. The optical device according to claim 8, characterized in that, The aperture cross-section of the at least one aperture array is 1.3 to 2 times the cross-section of the Gaussian beam at the corresponding location.

10. The optical device according to any one of claims 1 to 6, characterized in that, To perform pulse compression or pulse shortening, gratings, prisms, GDD mirrors, and / or GTI mirrors are positioned behind the multichannel unit along the beam propagation direction.

11. The optical device according to any one of claims 1 to 6, characterized in that, It is provided with at least one additional multichannel unit for increasing the bandwidth.

12. The optical device according to claim 11, characterized in that, At least one additional device consisting of a grating, a prism, a GDD mirror, and / or a GTI mirror is disposed behind the additional multichannel unit for pulse shortening.

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