Laser beam combining device, light source equipment and photoetching system

Abstract

The invention relates to a laser beam combining device, light source equipment and a photoetching system. The laser beam combining device comprises: a beam splitting module configured to split a laser beam into a plurality of sub-beams, where the plurality of sub-beams are linearly polarized; the polarization control module is configured to adjust polarization directions of the plurality of sub-beams to output a plurality of adjusted sub-beams, a first part of the plurality of adjusted sub-beams has a first polarization direction, and a second part of the plurality of adjusted sub-beams has a second polarization direction; the first polarization direction and the second polarization direction are orthogonal to each other; and a focusing module configured to focus the plurality of adjusted sub-beams at a target position.

Description

Technical Field

[0001] This application relates to the field of lasers, and more particularly to a laser beam combining device, a light source device, and a lithography system. Background Art

[0002] High-power pulsed lasers have important application prospects in the fields of high-precision laser processing, biomedical engineering, strong-field physics research, etc. In most application scenarios of high-power lasers, the power density of the focused laser at the focal point is the primary factor affecting the application effect. When the increase in the power of a single laser beam is limited, laser beam combining is an effective means to significantly increase the laser power.

[0003] Laser beam combining refers to separately amplifying multiple laser beams and then combining them into a single high-power laser beam. Laser beam combining is divided into incoherent beam combining, coherent beam combining, etc. Incoherent beam combining means that no control is exerted over the phases, polarization directions, etc. of the individual beams, and the power density after beam combining exhibits geometric superposition. The polarization and phase of incoherent beam combining are random, which can lead to instability in the spatial light field distribution at the focal position. Coherent beam combining means controlling the individual beams to have the same wavelength and polarization direction and locking the relative phases. After coherent beam combining, the local power density increases exponentially, which is a common beam combining method at present and can be used, for example, in ultra-short and ultra-intense laser ignition devices. However, coherent beam combining is accompanied by beam interference, which can cause interference fringes to appear at the focal position, resulting in non-uniform spatial distribution of the light field and relatively high requirements for multi-beam phase matching. For example, in a high-power CO2 laser beam combining system, air flow disturbances can cause random optical path differences, resulting in a disordered interference light field distribution at the focal position.

[0004] Therefore, how to generate a laser beam combination with a uniform spatial distribution of the light field and not affected by phase disturbances is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To solve the above problems, an exemplary embodiment of the present application provides a laser beam combining device, including: a beam splitting module configured to split a laser beam into a plurality of sub-beams, wherein the plurality of sub-beams are linearly polarized; a polarization control module configured to adjust the polarization directions of the plurality of sub-beams to output a plurality of adjusted sub-beams, wherein a first part of the plurality of adjusted sub-beams has a first polarization direction, a second part of the plurality of adjusted sub-beams has a second polarization direction, and the first polarization direction and the second polarization direction are orthogonal to each other; and a focusing module configured to focus the plurality of adjusted sub-beams at a target position.

[0006] The laser beam combining device of the present application can achieve decoherent beam combining by utilizing the characteristic that orthogonally polarized beams do not interfere, so that the spatial power density distribution at the target position after beam combining and focusing is uniform.

[0007] Optionally, the polarization control module includes a plurality of phase retarders, each phase retarder configured to convert the polarization state of a corresponding sub-beam of the plurality of sub-beams into circular polarization.

[0008] Optionally, the first polarization direction and the second polarization direction are left-handed circular polarization and right-handed circular polarization, respectively.

[0009] Optionally, the phase retarder is a reflective phase retarder or a transmissive phase retarder.

[0010] Optionally, the polarization control module further includes a plurality of polarizers, each polarizer being disposed optically upstream of a corresponding one of the plurality of phase retarders and configured to match the polarization direction of a corresponding sub-beam of the plurality of sub-beams.

[0011] Optionally, the polarizer is a polarizing film or an absorptive thin-film reflector.

[0012] Optionally, the polarization control module includes a plurality of phase retarders, each phase retarder configured to adjust the linear polarization direction of a corresponding sub-beam of the plurality of sub-beams, and the phase retarder includes a half-wave plate.

[0013] Optionally, the first polarization direction and the second polarization direction are S polarization and P polarization, respectively.

[0014] Optionally, the polarization control module further includes a Faraday isolator disposed optically downstream of the phase retarder.

[0015] Optionally, the laser beam combining device further includes an amplification module, where the amplification module is arranged: between the beam splitting module and the polarization control module for amplifying the plurality of sub-beams to output a plurality of amplified sub-beams to the polarization control module; or between the polarization control module and the focusing module for amplifying the plurality of adjusted sub-beams to output a plurality of amplified sub-beams to the focusing module.

[0016] Optionally, the amplification module includes a single-stage amplifier or a multi-stage amplifier.

[0017] Optionally, the laser beam combining device further includes a delay adjustment module, where the delay adjustment module is disposed between the beam splitting module and the focusing module for adjusting the optical path of each sub-beam of the plurality of sub-beams to reach the target position.

[0018] Optionally, at least two sub-beams focused at the target position are adjacent to each other and respectively have the first polarization direction and the second polarization direction.

[0019] Optionally, the included angle between the at least two sub-beams is less than a set threshold value.

[0020] Optionally, the laser beam combining device further includes a random phase plate disposed between the focusing module and the target position.

[0021] The present application also provides a light source device, including: a laser configured to output a laser beam; and the laser beam combining device as described above.

[0022] The present application also provides a lithography system, including the light source device as described above. Description of the Drawings

[0023] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings, where:

[0024] Figure 1 Shows a schematic block diagram of a laser beam combining device according to an exemplary embodiment of the present application.

[0025] Figure 2 、 Figure 3 and Figure 4 Respectively show several examples of the polarization control module.

[0026] Figure 5 and Figure 6 Respectively show schematic block diagrams of different embodiments of a laser beam combining device including an amplification module.

[0027] Figure 7 Shows a schematic block diagram of a laser beam combining device including a delay adjustment module.

[0028] Figure 8 Shows a schematic block diagram of a laser beam combining device according to a first example of the present application.

[0029] Figure 9 Shows a schematic block diagram of a laser beam combining device according to a second example of the present application.

[0030] Figure 10A and Figure 10B Respectively show the spatial distributions of coherent beam combining and incoherent beam combining.

[0031] Figure 11 Shows a schematic block diagram of the light source device 1100.

[0032] Figure 12A and Figure 12BSchematic diagrams of the decoherence beam combination polarization schemes for different targets are respectively shown.

[0033] Figure 13 A schematic block diagram of a laser beam combination device according to an alternative embodiment of the present application is shown.

[0034] Figure 14 A schematic diagram of a beam combination scheme with a random phase plate added is shown. Detailed implementation manners

[0035] To make the above objects, features, and advantages of the present application more apparent and understandable, the following will describe the detailed implementation manners of the present application in conjunction with the accompanying drawings.

[0036] In the following description, many specific details are set forth to facilitate a thorough understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0037] Secondly, the present application is described in detail in conjunction with schematic diagrams. When detailing the embodiments of the present application, for ease of explanation, the cross-sectional views showing the device structure will be enlarged locally out of the general scale, and the schematic diagrams are only examples and should not limit the scope of protection of the present application herein. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0038] Please note all the documents and literature submitted simultaneously with this specification and open to the public for reviewing this specification, and the content of all such documents and literature is incorporated herein by reference. Unless otherwise directly stated, all the features disclosed in this specification (including any appended claims, abstract, and drawings) can be replaced by alternative features for achieving the same, equivalent, or similar purposes. Therefore, unless otherwise clearly stated, each disclosed feature is only an example of a group of equivalent or similar features.

[0039] As used herein, the terms "above...", "below...", "between...", and "on..." refer to the relative position of this layer with respect to other layers. Similarly, for example, a layer deposited or placed above or below another layer may be in direct contact with the other layer or may have one or more intermediate layers. In addition, a layer deposited or placed between layers may be in direct contact with these layers or may have one or more intermediate layers. In contrast, the first layer "on" the second layer is in contact with the second layer. In addition, the relative position of a layer with respect to other layers is provided (assuming deposition, modification, and removal of thin films with respect to the starting substrate without considering the absolute orientation of the substrate).

[0040] Unless otherwise defined, technical terms or scientific terms used in the claims and the specification shall have the ordinary meanings as understood by those of ordinary skill in the technical field to which this application pertains. The terms "first", "second" and similar terms used in the specification and claims of this patent application do not denote any order, quantity or importance, but are merely used to distinguish different components. The terms such as "a" or "an" do not denote a quantity limitation, but mean that there is at least one. The terms such as "comprising" or "including" mean that the elements or objects appearing before "comprising" or "including" cover the elements or objects listed after "comprising" or "including" and their equivalent elements, and do not exclude other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0041] In this application, a structure may be referred to as "configured to" or "capable of" performing certain tasks, even if the structure is not currently being operated. For example, a "laser configured to / capable of outputting a laser beam" is intended to cover a laser having components that perform this function during operation, even if the laser is not currently in use (e.g., not powered on).

[0042] In this application, if not otherwise specified, all the embodiments and preferred embodiments mentioned herein may be combined with each other to form new technical solutions. In this application, if not otherwise specified, all the technical features and preferred features mentioned herein may be combined with each other to form new technical solutions.

[0043] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0044] For ease of description, it can be considered that light propagates along the optical path in the light beam from an optical "upstream" position to an optical "downstream" position. Therefore, the relative positions of optical elements in the optical path can also be described using these two terms.

[0045] The laser beam combining device provided according to the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0046] Reference Figure 1 , in which Figure 1 shows a schematic block diagram of a laser beam combining device 100 according to an exemplary embodiment of this application.

[0047] The laser beam combining device 100 may include a beam splitting module 110, a polarization control module 120, and a focusing module 130.

[0048] As Figure 1 shown, the beam splitting module 110 may split a laser beam into N sub-beams 11 (e.g., sub-beam 11-1, sub-beam 11-2,..., sub-beam 11-N), where N is greater than or equal to 2. The N sub-beams may be linearly polarized.

[0049] In some embodiments of the present application, the laser beam may be linearly polarized, and the beam splitting module 110 may include a beam splitter and be configured to split the linearly polarized laser beam into N linearly polarized sub-beams. In other embodiments of the present application, the laser beam may be non-linearly polarized, and the beam splitting module 110 may include a polarization beam splitter to perform polarization splitting on the laser beam, thereby generating N linearly polarized sub-beams.

[0050] The polarization control module 120 may be configured to adjust the polarization directions of the N sub-beams 11 to output N adjusted sub-beams 12 (e.g., adjusted sub-beam 12-1, adjusted sub-beam 12-2,..., adjusted sub-beam 12-N). The first part of the plurality of adjusted sub-beams 12 may have a first polarization direction. The second part of the plurality of adjusted sub-beams 12 may have a second polarization direction. The first polarization direction and the second polarization direction may be orthogonal to each other. For example, the adjusted sub-beams 12-1, 12-3, 12-5,..., 12-(N-1) may have the first polarization direction, and the adjusted sub-beams 12-2, 12-4, 12-6,..., 12-N may have the second polarization direction. The polarization directions of the adjusted sub-beam 12-1 and the adjusted sub-beam 12-2 are orthogonal to each other, the polarization directions of the adjusted sub-beam 12-2 and the adjusted sub-beam 12-3 are orthogonal to each other,..., and the polarization directions of the adjusted sub-beam 12-(N-1) and the adjusted sub-beam 12-N are orthogonal to each other.

[0051] The focusing module 130 may focus the plurality of adjusted sub-beams 12 at the target position 20.

[0052] The laser beam combining device 100 of the present application allows for achieving decoherence beam combining by utilizing the characteristic that non-interfering beams with orthogonal polarizations do not interfere, avoiding the appearance of interference fringes at the target position 20. At the same time, due to the phase-independent characteristic of decoherence beam combining, phase perturbations do not affect the light field distribution at the target position 20, achieving a uniform spatial distribution of the light field.

[0053] In some embodiments of the present application, the polarization control module 120 may include a plurality of phase retarders. Each phase retarder may be disposed on the corresponding optical path of the corresponding sub-beam 11-i (1 ≤ i ≤ N), and may convert the polarization state of the corresponding sub-beam 11-i into circular polarization. Each phase retarder may introduce a phase difference for each sub-beam 12. For example, the phase retarder may be a λ / 4 phase retarder. In this context, "phase retardation" refers to the relative phase retardation between the horizontal and vertical polarization direction components, and is independent of the fast-changing phase of the laser beam. The phase retarder may be a reflective phase retarder or a transmissive phase retarder (e.g., a quarter-wave plate). Such a phase difference may convert linearly polarized light into circularly polarized light, where the polarization direction varies with the specific direction of the wave plate. If the polarization direction of the incident linearly polarized light forms an angle of 45 degrees (or -45 degrees) with the principal axis (transmission direction) of the λ / 4 phase retarder (introducing a phase difference of 90 degrees), then after transmission or reflection through the λ / 4 phase retarder, the linearly polarized light will become left-handed circularly polarized light (or right-handed circularly polarized light).

[0054] In some embodiments of the present application, the polarization directions of at least two of the plurality of adjusted sub-beams 12 output by the polarization control module 120 may be left-handed circular polarization and right-handed circular polarization, respectively. For example, the polarization direction of the adjusted sub-beam 12-i may be left-handed circularly polarized light, while the polarization direction of the adjusted sub-beam 12-(i + 1) may be right-handed circularly polarized light.

[0055] In some embodiments of the present application, in addition to the first part of the sub-beams and the second part of the sub-beams, the plurality of adjusted sub-beams 12 may further include a third part of the sub-beams. The third part of the sub-beams may have a third polarization direction. The third polarization direction and the first polarization direction may not be orthogonal to each other. The third polarization direction and the second polarization direction may not be orthogonal to each other.

[0056] In some embodiments of the present application, the polarization control module 120 may further include a plurality of polarizers, which is beneficial to achieving spatial optical isolation. Each polarizer may be disposed on the corresponding optical path of the corresponding sub-beam 11-i (1 ≤ i ≤ N), upstream optically of the corresponding phase retarder and configured to match the polarization direction of the corresponding sub-beam 11-i. In this context, "the polarizer matches the polarization direction of the corresponding sub-beam 11-i" means that the corresponding sub-beam 11-i can pass through the polarizer without being blocked or absorbed by the polarizer. The polarizer may include a polarizing film or an absorptive thin-film reflector.

[0057] In some embodiments of the present application, at least a pair of adjacent sub-beams focused at the target position respectively have a first polarization direction and a second polarization direction orthogonal to each other when output from the polarization control module 120. In the present application, "adjacent sub-beams" refers to two sub-beams whose included angle with each other is less than a set threshold and there are no other sub-beams between them. The set threshold can be any angle between 20 degrees and 70 degrees, such as 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees or 70 degrees. The set threshold can be related to the requirement of the uniformity of the light field distribution. Figures 2 to 4 Several examples of the polarization control module 120 are respectively shown.

[0058] In Figure 2 the example of, the polarization control module 120 may have a transmissive optical path and include a polarizer 121 and a quarter-wave plate 122. The polarizer 121 matches the polarization direction of the incident light (linearly polarized light) 200. In this example, the incident light 200 can pass through the polarizer 121, be converted into left-handed circularly polarized light after passing through the quarter-wave plate 122, and the returned light 200' after reflection is converted into right-handed circularly polarized light. The returned light 200' is converted back into linearly polarized light after passing through the quarter-wave plate 122. The polarization direction of the converted returned light 200' is perpendicular to the polarization direction of the incident light 200 and cannot pass through the polarizer 121, thereby achieving isolation of the returned light.

[0059] In Figure 3 the example of, the polarization control module 120 may have a reflective optical path and include an absorptive thin-film reflector 123 and a reflective phase retarder 124. For example, the absorptive thin-film reflector 123 can absorb the horizontally polarized incident light and reflect the vertically polarized incident light. In this example, the incident light 300 (assumed to be vertically polarized linearly polarized light) can be reflected by the absorptive thin-film reflector 123 to the reflective phase retarder 124, and the linearly polarized light is converted into left-handed circularly polarized light after being reflected by the reflective phase retarder 124, and the returned light 300' after reflection is converted into right-handed circularly polarized light. The returned light 300' is converted into horizontally polarized linearly polarized light after being reflected by the reflective phase retarder 124. The polarization direction of the converted returned light 300' is perpendicular to the polarization direction of the incident light 300, so the returned light is absorbed by the absorptive thin-film reflector 123, thereby achieving isolation of the returned light. The advantage of the polarization control module 120 adopting a reflective optical path is that the laser beam combining device 100 can be applied to a high-power laser system, because the polarization control module 120 can adopt reflective elements combined with a backside heat dissipation structure to promote high-power laser beam combining.

[0060] In some embodiments of the present application, the polarization control module 120 may include a half-wave plate 125 configured to adjust the linear polarization direction of a plurality of sub-beams 11. AsFigure 4 As shown, the incident light (linearly polarized light) 400 can pass through the half-wave plate 125 to change the linear polarization direction. In this embodiment, the adjusted sub-beam 12-i output by the polarization control module 120 can be S-polarized light or P-polarized light. As an example, the polarization direction of the adjusted sub-beam 12-i can be S-polarized, while the polarization direction of the adjusted sub-beam 12-(i + 1) can be P-polarized. Preferably, the polarization control module 120 can further include a Faraday isolator 126 disposed downstream of the half-wave plate 125 optically, configured to isolate the return light 400'.

[0061] In some embodiments of the present application, the laser beam combining device 100 can further include an amplification module for amplifying a plurality of sub-beams to achieve high-power output. The amplification module can include a single-stage amplifier or a multi-stage amplifier. Figure 5 and Figure 6 FIGS. respectively show schematic block diagrams of different embodiments of the laser beam combining device 100 including the amplification module 140.

[0062] As Figure 5 shown, the amplification module 140 can be disposed between the beam splitting module 110 and the polarization control module 120 to amplify a plurality of sub-beams 11 to output a plurality of amplified sub-beams 14 (e.g., amplified sub-beam 14-1, amplified sub-beam 14-2,..., amplified sub-beam 14-N) to the polarization control module 120.

[0063] As Figure 6 shown, the amplification module 140 can be disposed between the polarization control module 120 and the focusing module 130 to amplify a plurality of sub-beams 12 to output a plurality of amplified sub-beams 14 (e.g., amplified sub-beam 14-1, amplified sub-beam 14-2,..., amplified sub-beam 14-N) to the focusing module 130.

[0064] Since the optical path lengths of the respective sub-beams 11 (reaching the target position 20) may be different, the optical paths of the respective sub-beams 11 can be adjusted to make the optical paths of the light pulses of the respective sub-beams 11 reaching the target position 20 the same. Therefore, in some embodiments of the present application, the laser beam combining device can further include a delay adjustment module. The delay adjustment module can be disposed at any position on the optical path between the beam splitting module 110 and the focusing module 130 to adjust the optical path of each sub-beam reaching the target position 20. In this way, it can help the respective sub-beams to reach the target position 20 simultaneously.

[0065] Figure 7 FIG. shows a schematic block diagram of the laser beam combining device 100 including the delay adjustment module 150. As Figure 7As shown, the delay adjustment module 150 can be disposed between the beam splitting module 110 and the amplification module 140 (if any) to adjust the optical path lengths of the respective sub-beams 11 so that the optical pulses of the respective sub-beams 11 reach the target position 20 simultaneously. It should be noted that although Figure 7 the delay adjustment module 150 is shown as being located between the beam splitting module 110 and the amplification module 140, the present application is not limited thereto. The delay adjustment module 150 can be disposed at any position on the optical path between the beam splitting module 110 and the focusing module 130, such as between the amplification module 140 and the polarization control module 120, or between the polarization control module 120 and the focusing module 130.

[0066] See Figure 8 , which shows a schematic block diagram of a laser beam combining device 800 according to a first example of the present application. The laser beam combining device 800 can include a beam splitting module 810, a polarization control module 820, a focusing module 830, an optional amplification module 840, and an optional delay adjustment module 850.

[0067] As Figure 8 shown, the beam splitting module 810 can split a laser beam into N sub-beams propagating on N optical paths (optical path 1, optical path 2,..., optical path N). The polarization control module 820 can include a delay adjuster 821 and a polarizer 822 respectively disposed on each optical path (such as optical path i, i = 1, 2,..., N - 1, N). The focusing module 830 can include a focusing optical assembly 831 respectively disposed on each optical path (such as optical path i). The optional amplification module 840 can include one or more stages of amplifiers 841 respectively disposed on each optical path (such as optical path i). The optional delay adjustment module 850 can include a delay adjuster 851 respectively disposed on each optical path (such as optical path i). It can be seen that each optical path (such as optical path i) includes its own delay adjuster 851, amplifier 841, polarizer 822, phase retarder 821, and focusing optical assembly 831.

[0068] The input laser beam of the laser beam combining device 800 can be generated by an external seed laser. The transmission of the input laser beam in the laser beam combining device 800 is as follows: The laser beam is divided into N sub-beams, and each sub-beam is linearly polarized; after each sub-beam passes through each delay regulator 851, high-power output is achieved through each amplifier 841, and linear polarization is maintained; each sub-beam passes through a polarizer 822 and a phase retarder 821 in its respective optical path; each polarizer 822 is adjusted to match the polarization direction of each sub-beam; each phase retarder 821 is adjusted to convert the polarization direction of each sub-beam into circular polarization, and the polarization directions of at least two sub-beams are respectively left-handed circular polarization and right-handed circular polarization to achieve incoherent beam combining; each focusing optical group 831 is adjusted to focus the directions of each beam on the target position 20; the delay regulators 851 of each optical path are adjusted to ensure that each laser pulse reaches the focus (i.e., the target position 20) simultaneously.

[0069] In the laser beam combining device 800, at least two sub-beams focused at the target position 20 are adjacent to each other, and the included angle θ between them can be less than a set threshold. The set threshold can be any angle between 20 degrees and 70 degrees, such as 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, or 70 degrees. The set threshold can be related to the requirement of the uniformity of the light field distribution.

[0070] See Figure 9 , which shows a schematic block diagram of a laser beam combining device 900 according to a second example of the present application. The laser beam combining device 900 can include a beam splitting module 910, a polarization control module 920, a focusing module 930, an optional amplification module 940, and an optional delay adjustment module 950.

[0071] As Figure 9 shown, the beam splitting module 910 can split the laser beam into N sub-beams propagating on N optical paths (optical path 1, optical path 2,..., optical path N). The polarization control module 920 can include a Faraday isolator 921 and a half-wave plate 922 respectively provided on each optical path (such as optical path i, i = 1, 2,..., N - 1, N). The focusing module 930 can include a focusing optical group 931 respectively provided on each optical path (such as optical path i). The optional amplification module 940 can include one or more stages of amplifiers 941 respectively provided on each optical path (such as optical path i). The optional delay adjustment module 950 can include a delay regulator 951 respectively provided on each optical path (such as optical path i). It can be seen that each optical path (such as optical path i) includes its own delay regulator 951, amplifier 941, half-wave plate 922, Faraday isolator 921, and focusing optical group 931.

[0072] The input laser beam of the laser beam combining device 900 can be generated by an external seed laser. The transmission of the input laser beam in the laser beam combining device 900 is as follows: The laser beam is divided into N sub-beams, and each sub-beam is linearly polarized; after each sub-beam passes through each delay adjuster 951, high-power output is achieved through each amplifier 941, and linear polarization is maintained; each sub-beam passes through the half-wave plate 922 and the Faraday isolator 921 in its respective optical path; each half-wave plate 922 is adjusted to adjust the polarization direction of each sub-beam, and the linear polarization directions of at least two sub-beams are made to be S polarization and P polarization respectively to achieve incoherent beam combining; each focusing optical group 931 is adjusted to focus the directions of each beam on the target position 20; the delay adjusters 0951 of each optical path are adjusted to ensure that each laser pulse reaches the focal point (i.e., the target position 20) simultaneously.

[0073] In the laser beam combining device 900, at least two sub-beams focused at the target position 20 are adjacent to each other and the included angle β between them can be approximately 45 degrees, such as 45 degrees ± 10%.

[0074] Figure 10A and Figure 10B respectively show the spatial distributions of coherent beam combining and incoherent beam combining. Assuming two CO2 laser beams (amplitude normalized), they are focused on the target position at incident angles of ±20° respectively, and the beam waist radius is 15 μm. Figure 10A For the case of coherent beam combining, the focused light field presents fringe interference. Figure 10B For the case of incoherent beam combining, the focused light field shows a linear superposition distribution. Comparing Figure 10A and Figure 10B , it can be seen that incoherent beam combining has better spatial uniformity.

[0075] According to another exemplary embodiment of the present application, the present application also proposes a light source device.

[0076] Figure 11 Shows a schematic block diagram of the light source device 1100. The light source device 1100 may include a laser 1101 and the laser beam combining device 100 as described above. The laser 1101 may be configured to output a laser beam 11 for inputting an external seed laser to the laser beam combining device 100. It should be noted that the laser 1101 may output a linearly polarized laser beam 11 to be input into the beam splitting module 110 of the laser beam combining device 100, and the beam splitting module 110 may divide the linearly polarized laser beam 11 into N linearly polarized sub-beams; or the laser beam 11 output by the laser 1101 may also be non-linearly polarized, and the beam splitting module 110 may include a polarization beam splitter to perform polarization splitting on the laser beam 11, thereby generating N linearly polarized sub-beams.

[0077] According to another exemplary embodiment of the present application, the present application further provides a laser system. The laser system may include the light source device 1110 as described above.

[0078] In some embodiments, the laser system may be configured to perform various laser processing operations, such as laser cutting, laser marking, 3D printing, etc. Since the laser beam combining device 10 of the present application can make the spatial power density distribution at the focal position uniform after laser beam combining and focusing, the uniform irradiation effect of the processing point of the laser processing system can be improved.

[0079] In other embodiments, the laser system may be configured to perform a laser focusing and target shooting project. Since the laser beam combining device 10 of the present application can make the spatial power density distribution at the focal position uniform after laser beam combining and focusing, the uniform irradiation effect of the target surface of the laser system can be improved.

[0080] Figure 12A and Figure 12B respectively show schematic diagrams of the incoherent beam combining polarization schemes for different targets.

[0081] For a three-dimensional target, the circular polarization scheme described above can be adopted, that is, at least two adjacent light beams are used with their polarization directions being left-handed circular polarization and right-handed circular polarization respectively to irradiate the three-dimensional target. The shooting angle and the number of beam combinations depend on the shape and size of the focused spot and the target. For example, when irradiating a regular hexahedron, the number of beam combinations can be as many as 12. The polarization directions of at least a pair of adjacent sub-beams focused at the target position are orthogonal to each other. As Figure 12A shown, assuming that the adjusted sub-beams 12-1, 12-3, 12-5 are left-handed circularly polarized light and the adjusted sub-beams 12-2, 12-4, 12-6 are right-handed circularly polarized light, then the adjusted sub-beams 12-1 and 12-2 can be focused on the three-dimensional target 21 approximately from the first direction, the adjusted sub-beams 12-3 and 12-4 can be focused on the three-dimensional target 21 approximately from the second direction, and the adjusted sub-beams 12-5 and 12-6 can be focused on the three-dimensional target 21 approximately from the third direction.

[0082] Focusing from different directions can be achieved by setting a relay optical group in the laser system. The relay optical group may include one or more optical elements. For example, a relay optical group can be set upstream optically of the focusing module 130 to deflect the optical path, so that multiple adjusted sub-beams irradiate the three-dimensional target 21 at different shooting angles.

[0083] For a planar target, a circular polarization scheme can be selected. That is, by irradiating the front and back sides of the planar target with left-handed and right-handed circular light beams, circular polarization incoherent beam combination with 2-4 beam combinations can be achieved. Or a linear polarization scheme can also be selected, that is, irradiating the planar target (for example, the front and back sides of the planar target) with linearly polarized light whose polarization directions of adjacent light beams are orthogonal to each other, and the number of beam combinations can be up to 6. For example, as Figure 12B shown, three linearly polarized light beams (12-1, 12-2, 12-3) with orthogonal polarization directions of adjacent light beams can be used to irradiate the planar target 22. Assume that the adjusted sub-beam 12-1 and 12-3 are S-polarized light and the adjusted sub-beam 12-2 is P-polarized light. The adjusted sub-beam 12-1 and the adjusted sub-beam 12-2 do not interfere in some directions; the adjusted sub-beam 12-2 and the adjusted sub-beam 12-3 do not interfere in some directions; although the adjusted sub-beam 12-1 and the adjusted sub-beam 12-3 are both S-polarized light, since the angle between the adjusted sub-beam 12-1 and the adjusted sub-beam 12-3 can be set to 90 degrees, that is, orthogonal in space, they can also not interfere.

[0084] In some embodiments of the present application, the laser beam combination device 100 may further include a plurality of random phase plates 161. As Figure 13 shown, each random phase plate 161 can be arranged optically downstream of the focusing module 130 (for example, between the focusing module 130 and the target position 20) and configured to perform random phase modulation on the sub-beams output by the focusing module 130, for example, introducing different phase delays for different sub-beams. The present application does not aim to limit the number of beam combinations and the beam hitting angle of the laser beam combination device 100. However, if beams with the same polarization interfere due to similar hitting angles, random phase plates 161 can be added to achieve incoherent beam combination, and thus the spatial light field distribution at the focal position is more uniform, as Figure 14 shown.

[0085] According to another exemplary embodiment of the present application, the present application also proposes a lithography system. The lithography system may include the light source device as described above. In one embodiment, the lithography system can be configured to be used in extreme ultraviolet lithography processes (for example, LPP-EUV lithography processes).

[0086] The laser beam combining device according to the exemplary embodiments of the present application has been described in detail above. The present application overcomes the problem of uneven spatial light field at the focal position in traditional beam combining systems, and realizes decoherence beam combining by utilizing the characteristic that orthogonally polarized beams do not interfere, avoiding the appearance of interference fringes at the focal position. The present application can improve the stability of the beam combining system and is applicable to laser systems with different repetition frequencies. The present application utilizes the phase-independent characteristic of decoherence beam combining, and the phase perturbation in the system will not affect the focal light field distribution, greatly improving the stability. The present application utilizes the characteristics of polarization control technology to simultaneously achieve laser beam isolation and beam decoherence, combines the isolation module and the decoherence module (forming a single polarization control module), and the overall structure is simple and compact. The technical solution of the present application is applicable to laser systems with different powers. For high-power laser systems (for example, with a laser power greater than 100 W), high-power laser beam combining can be achieved by using reflective elements in combination with a backside heat dissipation structure.

[0087] Although the present application has been described with reference to the current specific embodiments, those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions can be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the spirit of the present application, they will fall within the scope of the claims of the present application.

[0088] It should be understood that this specification will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing detailed description, it can be seen that various features are combined in a single embodiment for the purpose of streamlining the present application. This method of the present application should not be construed as reflecting an intention that the claimed embodiments require more features than those expressly recited in each claim. On the contrary, as reflected in the appended claims, the inventive subject matter lies in less than all of the features of a single disclosed embodiment. Accordingly, the appended claims are hereby incorporated into the detailed description, where each claim stands on its own as a separate embodiment.

[0089] An embodiment or embodiments referred to in this description are intended that the specific features, structures, or characteristics described in connection with that embodiment are included in at least one embodiment of a circuit or method. The phrase "an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment.

Claims

1. A laser beam combining device, comprising: A beam splitting module configured to split a laser beam into a plurality of sub - beams, wherein the plurality of sub - beams are linearly polarized; A polarization control module configured to adjust the polarization directions of the plurality of sub - beams to output a plurality of adjusted sub - beams, wherein a first part of the plurality of adjusted sub - beams has a first polarization direction, a second part of the plurality of adjusted sub - beams has a second polarization direction, and the first polarization direction and the second polarization direction are orthogonal to each other; and A focusing module configured to focus the plurality of adjusted sub - beams at a target position.

2. The laser beam combining device according to claim 1, characterized in that, The polarization control module includes a plurality of phase retarders, each phase retarder configured to convert the polarization state of a corresponding sub - beam among the plurality of sub - beams into circular polarization, and the first polarization direction and the second polarization direction are left - hand circular polarization and right - hand circular polarization respectively.

3. The laser beam combining device according to claim 2, wherein The phase retarder is a reflective phase retarder or a transmissive phase retarder.

4. The laser beam combining device according to claim 2, characterized in that The polarization control module further includes a plurality of polarizers, each polarizer being disposed optically upstream of a corresponding one of the plurality of phase retarders and configured to match the polarization direction of a corresponding sub - beam among the plurality of sub - beams.

5. The laser beam combining device according to claim 4, wherein The polarizer is a polarizing plate or an absorptive thin - film reflector.

6. The laser beam combining device according to claim 1, wherein The polarization control module includes a plurality of phase retarders, each phase retarder configured to adjust the linear polarization direction of a corresponding sub - beam among the plurality of sub - beams, the phase retarder includes a half - wave plate, and the first polarization direction and the second polarization direction are S - polarization and P - polarization respectively.

7. The laser beam combining device according to claim 6, wherein The polarization control module further includes a Faraday isolator disposed optically downstream of the phase retarder.

8. The laser beam combining device according to claim 1, wherein, The laser beam combining device further includes an amplification module, wherein the amplification module is arranged: Between the beam splitting module and the polarization control module for amplifying the plurality of sub - beams to output a plurality of amplified sub - beams to the polarization control module; Or Between the polarization control module and the focusing module for amplifying the plurality of adjusted sub - beams to output a plurality of amplified sub - beams to the focusing module.

9. The laser beam combining device according to claim 8, wherein, The amplification module includes a single - stage amplifier or a multi - stage amplifier.

10. The laser beam combining device according to claim 1, wherein, The laser beam combining device further includes: A delay adjustment module, wherein the delay adjustment module is disposed between the beam splitting module and the focusing module for adjusting the optical path of each of the plurality of sub - beams to reach the target position; and / or A random phase plate disposed between the focusing module and the target position.

11. The laser beam combining device according to claim 1, wherein, At least two sub - beams focused at the target position are adjacent to each other and respectively have the first polarization direction and the second polarization direction.

12. The laser beam combining device according to claim 11, wherein The angle between the at least two sub - beams is less than a set threshold.

13. A light source device, comprising: A laser configured to output a laser beam; And The laser beam combining device according to any one of claims 1 - 12.

14. A lithography system, comprising the light source device according to claim 13.

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