Laser processing equipment and pulse modulation equipment

Abstract

This application relates to a laser processing apparatus and a pulse modulation apparatus. The laser processing apparatus includes: an ultrashort pulse laser for emitting an incident laser beam; a beam splitting module deployed on the optical path of the incident laser beam emitted by the ultrashort pulse laser for splitting the incident laser beam into multiple sub-beams; an optical path difference adjustment module deployed on the transmission optical path of at least one of the sub-beams after the output side of the beam splitting module, wherein the optical path difference between the sub-beams is adjusted after passing through the optical path difference adjustment module; and a beam combining module deployed on the common transmission optical path of the sub-beams after the output side of the optical path difference adjustment module, wherein the sub-beams, after passing through the beam combining module, are incident on the same processing position on the substrate to be processed at different times along the same optical path. This method can improve product processing quality and reliability.

Description

Technical Field

[0001] This application relates to the field of laser processing technology, and in particular to a laser processing apparatus and a pulse modulation device. Background Technology

[0002] Through-Glass Via (TGV) is an advanced 3D packaging technology that enables vertical interconnects by forming micron-sized vias in a glass substrate. It is widely used in semiconductors, PCBs (Printed Circuit Boards), MEMS (Micro-Electro-Mechanical Systems), and microfluidics. Compared to traditional through-silicon vias (TSVs), TGV technology, with its high insulation, low RF loss, and excellent thermal stability of glass materials, exhibits significant advantages in high-frequency, highly integrated devices, making it one of the key solutions for future high-performance electronic packaging.

[0003] In related technologies, TGV processing is mainly based on laser-induced modification technology. First, a laser is used to selectively irradiate specific areas inside the glass, modifying the glass structure in the scanned area. Then, the modified glass is immersed in an etching solution. Due to the difference in etching rates between the modified and unmodified areas, the etching solution preferentially dissolves the modified portion, ultimately forming the desired microchannels. This method avoids the stress problems associated with mechanical drilling and is suitable for high-precision processing.

[0004] However, in the process of laser-induced modification, in order to ensure that the modified area meets the requirements of subsequent etching, the laser intensity has to be increased. The increase in laser intensity will further cause abnormal taper or morphological distortion in the modified area, and may even cause cracks in the unmodified area around the modified area, thereby reducing the processing quality and reliability of the product. Utility Model Content

[0005] Therefore, it is necessary to provide a laser processing device and a pulse modulation device that can improve the processing quality and reliability of products, addressing the aforementioned technical problems.

[0006] In a first aspect, this application provides a laser processing apparatus, which includes:

[0007] An ultrashort pulse laser is used to emit an incident laser beam.

[0008] A beam splitting module is deployed in the optical path of the incident laser beam emitted by an ultrashort pulse laser to split the incident laser beam into multiple sub-beams.

[0009] An optical path difference adjustment module is deployed on the transmission optical path of at least one sub-beam after the output side of the beam splitter module. After passing through the optical path difference adjustment module, the optical path difference generated between each sub-beam is...

[0010] The beam combining module is deployed on the common transmission optical path of each sub-beam after the light output side of the optical path difference adjustment module. After passing through the beam combining module, each sub-beam is incident on the same processing position on the substrate to be processed at different times and along the same optical path.

[0011] In one embodiment, the substrate to be processed is a light-transmitting solid substrate; the laser processing apparatus further includes:

[0012] The Bessel shaping module is deployed on the output side of the beam combining module. After each sub-beam passes through the Bessel shaping module, it is shaped into a Bessel beam.

[0013] In one embodiment, the ultrashort pulse laser includes a femtosecond laser.

[0014] In one embodiment, the optical path difference adjustment module includes a retroreflective device, which includes at least one of a hollow right-angle mirror, a hollow roof mirror, and a hollow retroreflector.

[0015] In one embodiment, the optical path difference adjustment module further includes at least one displacement module, each displacement module corresponding to each retroreflector, and each displacement module is connected to its corresponding retroreflector to adjust the position of its corresponding retroreflector.

[0016] In one embodiment, the number of sub-beams is two, including a first sub-beam and a second sub-beam;

[0017] An anti-reflection device is deployed on the transmission optical path of the first sub-beam; the transmission optical path of the first sub-beam also includes a first reflector; through the anti-reflection device, the first reflector, and the displacement module, an optically path-adjustable first retroreflection optical path is formed on the transmission optical path of the first sub-beam.

[0018] The laser processing apparatus also includes a mirror assembly, which is used to form a second retroreflection path with a fixed optical path in the transmission optical path of the second sub-beam.

[0019] In one embodiment, the laser processing apparatus further includes a beam scaling mechanism, which is deployed in the optical path of the incident laser beam emitted by the ultrashort pulse laser and on the light-inlet side of the beam splitting module, for adjusting the beam size of the cross-section of the incident laser beam along the incident direction.

[0020] In one embodiment, the number of sub-beams is two, including a first sub-beam and a second sub-beam;

[0021] The beam splitting module includes a polarization beam splitter, which is used to split the incident laser beam into a first sub-beam and a second sub-beam.

[0022] In one embodiment, the laser processing apparatus further includes a first beam splitting fine-tuning mechanism, which is disposed on the incident light path of the polarization beam splitter and is used to modulate the polarization direction of the incident laser beam incident on the polarization beam splitter to adjust the laser power of the first sub-beam and the second sub-beam.

[0023] In one embodiment, the laser processing apparatus further includes a second beam splitting fine-tuning mechanism disposed on the transmission optical path of at least one sub-beam to adjust the laser power of at least one sub-beam.

[0024] Secondly, this application also provides a pulse modulation device, wherein the modulated laser beam is used to process a transparent solid substrate, and the pulse modulation device includes:

[0025] A beam splitting module is deployed in the optical path of the incident laser beam emitted by an ultrashort pulse laser to split the incident laser beam into multiple sub-beams.

[0026] An optical path difference adjustment module is deployed on the transmission optical path of at least one sub-beam after the output side of the beam splitter module. After passing through the optical path difference adjustment module, the optical path difference generated between each sub-beam is...

[0027] The beam combining module is deployed on the common transmission optical path of each sub-beam behind the light-emitting side of the optical path difference adjustment module. After passing through the beam combining module, each sub-beam is incident on the same processing position on the light-transmitting solid substrate at different times and along the same optical path.

[0028] The aforementioned laser processing apparatus and pulse modulation device first emit an incident laser beam with a pulse width less than or equal to picoseconds from an ultrashort pulse laser. Then, a beam splitting module divides the single laser beam emitted by the ultrashort pulse laser into multiple sub-beams. Next, an optical path difference adjustment module adjusts the propagation path length of at least one sub-beam to create an optical path difference between the sub-beams. Subsequently, a beam combining module recombines the sub-beams with optical path differences onto the same optical path, ensuring that the sub-beams with optical path differences are ultimately incident precisely on the same processing position on the substrate at specific time intervals. This time-modulated multi-pulse action method can achieve sufficient ionization and effective modification of the material through cumulative effects without increasing the energy of a single pulse. This ensures that the modified area meets the requirements of subsequent etching while avoiding the nonlinear effects and thermal damage risks caused by excessive energy in single-pulse actions, reducing the risks of abnormal taper or morphological distortion in the modified area and cracks in the unmodified area. Therefore, it can significantly improve the processing quality and reliability of the product. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of a laser processing apparatus in one embodiment of this application;

[0031] Figure 2 This is a schematic diagram of the structure of a hollow right-angle reflector in one embodiment of this application;

[0032] Figure 3 This is a schematic diagram of the structure of a hollow roof ridge reflector in one embodiment of this application;

[0033] Figure 4 This is a schematic diagram of the structure of a hollow retroreflector in one embodiment of this application;

[0034] Figure 5 This is a schematic diagram of the optical path difference adjustment process in one embodiment of this application;

[0035] Figure 6 This is a schematic diagram of the pulse modulation device in one embodiment of this application;

[0036] Figure 7 This is a schematic diagram of the laser processing apparatus in another embodiment of this application;

[0037] Figure 8 This is a schematic diagram of the spatiotemporal morphology of a laser pulse in one embodiment of this application. Detailed Implementation

[0038] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0039] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0040] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0041] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0042] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0043] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0044] Through-Glass Via (TGV) is an advanced 3D packaging technology that enables vertical interconnects by forming micron-sized vias in a glass substrate. It is widely used in semiconductors, PCBs (Printed Circuit Boards), MEMS (Micro-Electro-Mechanical Systems), and microfluidics. Compared to traditional through-silicon vias (TSVs), TGV technology, with its high insulation, low RF loss, and excellent thermal stability of glass materials, exhibits significant advantages in high-frequency, highly integrated devices, making it one of the key solutions for future high-performance electronic packaging.

[0045] In related technologies, TGV processing is mainly based on laser-induced modification technology. First, a laser is used to selectively irradiate specific areas inside the glass, modifying the glass structure in the scanned area. Then, the modified glass is immersed in an etching solution. Due to the difference in etching rates between the modified and unmodified areas, the etching solution preferentially dissolves the modified portion, ultimately forming the desired microchannels. This method avoids the stress problems associated with mechanical drilling and is suitable for high-precision processing.

[0046] Modification can refer to using high-energy ultrashort pulse lasers with a pulse width of less than or equal to picoseconds to focus on the surface or interior of a transparent solid substrate. The laser energy induces changes in refractive index, crystal structure reconstruction, or the formation of metastable phases in a local area of ​​the substrate to be processed, thereby changing the chemical or physical properties of the area. This provides selectivity for subsequent chemical etching or a pretreatment state for other subsequent processing.

[0047] Transparent solid substrates can refer to materials that allow light of at least a certain wavelength to pass through and are solid in physical form, such as glass substrates and sapphire substrates.

[0048] However, to modify glass materials using related technologies, it is usually necessary to use laser beams with short pulse widths. In transparent materials such as glass, since these materials are generally transparent to low-intensity light, traditional linear absorption mechanisms are very inefficient. It is usually necessary to use laser beams with short pulse widths to concentrate laser energy in a short time, and through extremely high peak power, induce nonlinear effects such as multiphoton absorption, so that the laser energy can be absorbed not only on the surface, but also inside the material.

[0049] The modification of glass materials induced by laser beams with short pulse widths is a multi-stage nonlinear physical chain reaction. As a wide-bandgap insulator, glass, under the influence of visible to near-infrared lasers, suffers from insufficient single-photon energy to directly excite valence band electrons. However, through multiphoton absorption, electrons can transition from the valence band to the conduction band, forming initial free electrons. Subsequently, aided by inverse bremsstrahlung, the number of free electrons continuously multiplies through collisional ionization. When the free electron density reaches a critical value, avalanche ionization is triggered, forming a high-density free electron plasma with metallic properties. At this point, the material's absorption efficiency for laser energy is significantly improved, allowing for direct energy deposition and material modification through optical field coupling.

[0050] However, when the pulse width is small, the duration of a single laser pulse is too short. The concentration of free electrons and excitons has not yet reached its maximum before the laser pulse has finished working, resulting in a decrease in the opto-electric coupling efficiency. The effect of the material modification region does not meet the target requirements. For example, the aperture size, aspect ratio, and processing efficiency of the modified region do not meet the processing requirements of some applications.

[0051] In this situation, material modification can be achieved by increasing the peak power of the single pulse. However, on the one hand, the high peak power density of the laser beam easily induces nonlinear phenomena such as the Photoker effect, filamentation, and self-phase modulation, disrupting the stability of the beam's spatiotemporal distribution and causing abnormal taper or morphological distortion in the modified region. On the other hand, excessive energy deposition resulting from increasing the peak power of the laser beam can induce localized thermal stress concentration, which can exacerbate and expand microcrack propagation. This leads to a decrease in the processing quality and reliability of the product.

[0052] Based on this, embodiments of this application provide a laser processing apparatus, such as... Figure 1 As shown, the laser processing device includes an ultrashort pulse laser 102, a beam splitting module 104, an optical path difference adjustment module 106, and a beam combining module 108. The arrows indicate the propagation direction of the laser beam.

[0053] It should be noted that the laser processing device can be used to modify glass substrates during the processing of glass through holes, and it can also be used to directly apply lasers to the interior of other transparent solid substrates for material pretreatment. In one specific embodiment, the laser processing device of this disclosure is first used to control the laser beam to modify the transparent solid substrate, and then a slicing process is used to divide the substrate into different application sizes along the modified area. In these scenarios, for materials that are difficult to pretreat using a single-pulse laser, the laser processing device provided in this embodiment can be used to modulate the laser pulse into a multi-pulse sequence with optical path difference, and this multi-pulse sequence with optical path difference can be used to process the same position on the substrate to be processed. In this way, the laser pulse that arrives at the material first triggers a large number of free electrons and excitons, significantly improving the light absorption efficiency; then, the laser pulse that arrives at the material later can achieve efficient energy absorption and deposition, ultimately forming a more obvious material modification area, so that the aperture size, aspect ratio, and processing efficiency of the material modification area can meet the application requirements.

[0054] The incident laser beam can refer to a laser beam that can penetrate into the interior of the substrate to be processed and induce modification of the substrate.

[0055] The substrate to be processed can refer to the target object that directly bears the laser energy during the processing. When the laser processing device is used to process glass through holes, the substrate to be processed can refer to a glass substrate, or other light-transmitting solid substrates, such as quartz crystals, sapphire, etc. The specific substrate can be determined based on the application requirements, and this embodiment does not impose any restrictions on it.

[0056] In one exemplary embodiment, the substrate to be processed is a light-transmitting solid substrate. It is understood that although this embodiment is based on transparent or semi-transparent solid substrates such as glass, it can be applied, but is not limited to, to the processing of light-transmitting solid substrates.

[0057] When the substrate to be processed is a transparent solid substrate, the incident laser beam can be an ultrafast laser, that is, an ultrashort pulse laser beam with a pulse width less than or equal to picoseconds. Ultrafast lasers can focus megawatt-level peak power to a micrometer-level spot size, easily enabling power density to exceed GW / cm², and efficiently triggering nonlinear processes such as photon absorption.

[0058] In transparent or semi-transparent solid substrates such as glass, since these materials are usually transparent to low-intensity light, the traditional linear absorption mechanism is very inefficient. Usually, a laser beam with a small pulse width is needed to concentrate the laser energy in a short time and induce nonlinear effects such as multiphoton absorption through extremely high peak power, so that the laser energy can be absorbed not only on the surface, but also inside the material.

[0059] In one exemplary embodiment, the ultrashort pulse laser 102 can be a femtosecond laser. Furthermore, the pulse width of the incident laser beam emitted by the femtosecond laser can be less than or equal to 600 fs. The shorter the pulse width of the laser beam, the higher the peak power can be. By selecting an incident laser beam with a pulse width less than or equal to 600 fs, the laser processing apparatus provided in this disclosure can process the substrate to be processed, satisfying both the required laser peak power and the required energy deposition.

[0060] An ultrashort pulse laser 102 can refer to a laser capable of emitting an ultrashort pulse laser beam. An ultrashort pulse laser beam can refer to a laser beam with a pulse width on the order of picoseconds or less.

[0061] The beam splitter module 104 is an optical element that can split an incident laser beam into two or more sub-beams according to a specific ratio.

[0062] In this embodiment, the beam splitting module 104 is deployed on the light-emitting side of the ultrashort pulse laser 102 to split the incident laser beam emitted by the ultrashort pulse laser 102 into multiple sub-beams.

[0063] In some feasible implementations, the beam splitting module 104 may employ a polarization beam splitter.

[0064] A polarization beam splitter is an optical element capable of splitting or combining incident light beams based on their polarization characteristics. A polarization beam splitter can separate an unpolarized or mixed-polarized beam into two orthogonal linearly polarized beams, such as P-polarized and S-polarized beams, according to their polarization directions. It can also combine two orthogonal polarized beams into a single beam. Polarization beam splitters have high energy efficiency; after a laser beam is incident on the deflection beam splitting module 104, the polarization beam splitter can almost evenly distribute all the energy of the laser beam into the two sub-beams, thereby effectively reducing energy loss and ensuring subsequent modification effects.

[0065] Furthermore, polarization beam splitters can flexibly control the laser power ratio of the two sub-beams after splitting by adjusting the polarization direction of the incident laser beam. Therefore, polarization beam splitters have significant advantages in applications requiring dynamic adjustment of laser power distribution.

[0066] It is understandable that the beam splitting module 104 can also use other types of laser beam splitting components without polarization function, such as ordinary cubic beam splitter or thin film beam splitting module 104. These beam splitting elements have simple structure and low cost, and can meet application requirements without adjusting the laser power of the sub-beams after splitting.

[0067] The optical path difference adjustment module 106 can refer to a device capable of changing the physical length of the beam propagation path and adjusting the optical path difference between different beams by changing the physical length of the beam propagation path. The optical path difference adjustment module 106 is deployed on the transmission optical path of at least one sub-beam after the light output side of the beam splitting module 104. The optical path difference adjustment module 106 can adjust the propagation path length of at least one of the sub-beams, so that the optical paths of each sub-beam are different, thereby controlling the time difference of each sub-beam reaching the substrate to be processed.

[0068] In some feasible embodiments, the optical path difference adjustment module 106 may include a mirror group, an optical delay line or a liquid crystal phase modulator, etc. This disclosure does not limit the specific components of the optical path difference adjustment module 106.

[0069] In some feasible embodiments, the number of sub-beams can be two, that is, the sub-beams include a first sub-beam and a second sub-beam. In this case, the number of optical path difference adjustment modules 106 can be one or two. That is, the optical path difference adjustment module 106 can be deployed in the optical path of either the first sub-beam or the second sub-beam; or the optical path difference adjustment module 106 can be deployed in the optical paths of both the first sub-beam and the second sub-beam.

[0070] In some feasible implementations, the optical path difference adjustment module 106 may be deployed in at least part or all of the optical path in each sub-beam.

[0071] In some feasible implementations, the optical path difference adjustment module 106 may adjust the optical path difference by at least one of increasing the propagation path length and decreasing the propagation path length.

[0072] The beam combining module 108 can refer to an optical element capable of recombining multiple independently propagating beams onto the same optical axis.

[0073] In this embodiment, the beam combining module 108 is deployed on the common transmission optical path of each sub-beam after the output side of the optical path difference adjustment module 106, and is used to re-merge the sub-beams after optical path difference adjustment onto the same optical axis. In some feasible embodiments, the beam combining module 108 can be deployed at the starting position where the optical paths of each sub-beam intersect.

[0074] In some feasible implementations, if the beam splitter module 104 employs a polarization beam splitter, the beam combiner module 108 may employ a polarization beam combiner.

[0075] For illustrative purposes, this example uses two sub-beams, specifically a first sub-beam and a second sub-beam. A laser processing apparatus can be deployed on the laser path between the ultrashort pulse laser 102 and the substrate to be processed. This apparatus modulates the incident laser beam emitted by the ultrashort pulse laser 102. The modulated first and second sub-beams then act sequentially on the same processing position on the substrate at a certain time interval. During laser beam modulation, the laser beam emitted by the ultrashort pulse laser 102 first enters the beam splitting module 104 and is split into a first sub-beam L and a second sub-beam L'. The two sub-beams enter the beam combining module 108 along different optical paths. One or both sub-beams can undergo optical path adjustment via the optical path difference adjustment module 106 before entering the beam combining module 108. After optical path adjustment, the two sub-beams enter the beam combining module 108 sequentially, combine into a coaxial output, and finally focus on the same processing position on the substrate. The sub-beam that first reaches the substrate can trigger free electrons and excitons, which can significantly improve the light absorption efficiency and achieve higher laser utilization. The sub-beam that subsequently reaches the substrate can then undergo stronger energy deposition, resulting in more significant material modification.

[0076] In this embodiment, an incident laser beam with a pulse width less than or equal to picoseconds is first emitted by an ultrashort pulse laser. Then, a beam splitting module divides the single laser beam emitted by the ultrashort pulse laser into multiple sub-beams. Next, an optical path difference adjustment module adjusts the propagation path length of at least one sub-beam to create an optical path difference between the sub-beams. Subsequently, a beam combining module recombines the sub-beams with optical path differences onto the same optical path, ensuring that the sub-beams with optical path differences are ultimately incident precisely on the same processing position on the substrate at a certain time interval. This time-modulated multi-pulse action method can achieve sufficient ionization and effective modification of the material through cumulative effects without increasing the energy of a single pulse. This ensures that the modified area meets the requirements of subsequent etching while avoiding the nonlinear effects and thermal damage risks caused by excessive energy in single-pulse actions, reducing the risks of abnormal taper or morphological distortion in the modified area and cracks in the unmodified area. Therefore, it can significantly improve the processing quality and reliability of the product.

[0077] In one exemplary embodiment, the substrate to be processed is a light-transmitting solid substrate; the laser processing apparatus further includes:

[0078] The Bessel shaping module is located on the output side of the beam combining module. After each sub-beam passes through the Bessel shaping module, it is shaped into a Bessel beam.

[0079] Among them, the Bessel shaping module can refer to an optical element used to convert a traditional Gaussian beam into a Bessel beam. The Bessel shaping module can modulate the phase of the wavefront of the laser beam incident on it to generate a Bessel beam with non-diffraction characteristics.

[0080] A Bessel beam is a theoretically diffractive beam whose transverse intensity distribution is described by a Bessel function. The depth of focus of a Bessel beam can be more than 1000 times that of a Gaussian beam, and its energy is more concentrated in long, slender regions, making it more suitable for processing high aspect ratio structures. Its high-intensity core region can efficiently trigger multiphoton absorption and avalanche ionization, enabling precise internal processing of materials in transparent solid substrates.

[0081] For example, by deploying a shaping module in the optical path after beam combining, each sub-beam can be shaped into a Bessel beam before it is incident on the substrate to be processed, and then the Bessel beam can be used to process the transparent solid substrate.

[0082] In one exemplary embodiment, the optical path difference adjustment module includes a retroreflective device, which includes a hollow right-angle mirror, a hollow roof mirror, and a hollow retroreflector.

[0083] Retroreflective devices refer to optical elements that can reflect incident light back in a direction opposite to the incident direction. Retroreflective devices can include mirror assemblies, hollow right-angle mirrors, hollow roof mirrors, and hollow retroreflectors, etc.

[0084] A hollow right-angle mirror can refer to a hollow solid angle structure composed of two mutually perpendicular reflecting surfaces. For example... Figure 2 As shown, the dashed line indicates the direction of beam propagation. The incident light first strikes one of the reflecting surfaces 202, is reflected to the other reflecting surface 204, and after being reflected twice, returns in the opposite direction to the incident direction.

[0085] A hollow roof reflector can refer to a retroreflective optical device consisting of two mutually perpendicular plane mirrors. For example... Figure 3 As shown, the dashed line indicates the direction of beam propagation. The incident light first enters one of the reflectors 302, is reflected to the other reflector 304, and after being reflected twice, returns in the opposite direction to the incident direction.

[0086] A hollow retroreflector can refer to a corner prism composed of three front-surface mirrors. For example... Figure 4As shown, the dashed line indicates the beam propagation direction. The incident light first strikes one of the reflectors, is reflected to the second reflector, and then to the third reflector. After being reflected three times, it returns in the opposite direction to the incident direction. Compared to retroreflectors composed of two reflectors, hollow retroreflectors composed of three reflectors exhibit stronger robustness to alignment errors and positional changes. As long as the incident light can simultaneously illuminate all three reflectors, the outgoing light will be strictly parallel to the incident light and will not be affected by the rotation or tilt of the device, resulting in higher stability of retroreflection. Thus, in practical applications, even if there are slight vibrations, displacements, or angular drifts in the mounting platform, the retroreflector can still ensure the stability of the optical path without the need for precise and cumbersome alignment adjustments. Retroreflectors composed of three reflectors have little impact on the polarization state of polarized light, almost no effect on polarization. When using polarization beam splitters and polarization beam combiners, they can better ensure that the sub-beams maintain their own polarization states, thus achieving successful beam combining.

[0087] For example, in order to make each sub-beam arrive at the substrate to be processed at different times, retroreflective devices can be deployed in the optical paths of some or all of the sub-beams. The propagation path length of the sub-beam in its optical path can be adjusted by using the retroreflective devices, so that each sub-beam arrives at the substrate to be processed at different times after traveling along propagation paths of different lengths.

[0088] In an exemplary embodiment, the optical path difference adjustment module further includes at least one displacement module, each displacement module corresponding to each optical path difference adjustment module, and each displacement module being connected to its corresponding optical path difference adjustment module for adjusting the position of its corresponding optical path difference adjustment module.

[0089] The displacement module can refer to a mechanical device that can drive the optical path difference adjustment module to move.

[0090] In some feasible implementations, the displacement module may include a precision motor and a precision guide rail. The displacement module can adjust the position of the retroreflector and drive the retroreflector along the guide rail to adjust the propagation path length of the sub-beam, thereby assisting the retroreflector in efficiently and accurately controlling the optical path of the sub-beam in its optical path.

[0091] For example, the retroreflective device can be moved by a displacement module, thereby controlling the propagation path length of the sub-beams. This helps the retroreflective device to efficiently and accurately control the optical path of the sub-beams in the optical path, so that each sub-beam arrives at the substrate to be processed after traveling along propagation paths of different lengths and after different propagation times.

[0092] In some feasible implementations, the displacement module can adjust the position of the corresponding optical path difference adjustment module in a preset displacement direction, the preset displacement direction being parallel to at least one of the incident optical path and the outgoing optical path of the optical path difference adjustment module.

[0093] In one exemplary embodiment, the number of sub-beams is two, including a first sub-beam and a second sub-beam;

[0094] An anti-reflection device is deployed on the transmission optical path of the first sub-beam; the transmission optical path of the first sub-beam also includes a first reflector; through the anti-reflection device, the first reflector, and the displacement module, an optically path-adjustable first retroreflection optical path is formed on the transmission optical path of the first sub-beam.

[0095] The laser processing apparatus also includes a mirror assembly, which is used to form a second retroreflection path with a fixed optical path in the transmission optical path of the second sub-beam.

[0096] The retroreflection path can refer to the path that the light beam returns along after passing through the optical element, which is parallel to the incident direction. In other words, the retroreflection path includes two parallel but opposite light paths.

[0097] When there are two sub-beams, an optical path difference adjustment module can be deployed on the transmission optical path of one of the sub-beams. That is, a retroreflector, a first mirror, and a displacement module can be deployed on the transmission optical path of the first sub-beam. An adjustable optical path can be constructed through the retroreflector, the first mirror, and the displacement module. Meanwhile, a mirror group can be deployed on the transmission optical path of the other sub-beam. That is, a mirror group can be deployed on the transmission optical path of the second sub-beam. A fixed optical path can be constructed through the mirror group.

[0098] In some feasible implementations, when the optical path lengths of the first sub-beam and the second sub-beam are equal, by constructing a first retroreflection optical path and a second retroreflection optical path, the optical paths of the first sub-beam and the second sub-beam can be made optically mirror-symmetrical. Thus, the optical path length of the first sub-beam can be adjusted simply by changing the position of the retroreflector via a displacement module, thereby quickly adjusting the optical path difference between the first and second sub-beams.

[0099] As an example, such as Figure 5As shown, the incident laser beam emitted by the ultrashort pulse laser 502 is split into a first sub-beam and a second sub-beam by the beam splitter 504. The first sub-beam is reflected light, which is reflected by the first reflecting mirror 5063 and then incident on the retroreflector 5061. After returning along the original optical path, it is incident on the beam combiner 508. The second sub-beam is transmitted light, which is reflected by a mirror group composed of three reflecting mirrors 510 to form a retroreflection optical path and then incident on the beam combiner 508, where it is combined with the first sub-beam. The position of the mirror group deployed on the transmission optical path of the second sub-beam is fixed, thus the optical path of the second sub-beam is fixed. The retroreflector 5061 deployed on the transmission optical path of the first sub-beam is connected to the displacement module 5062. By adjusting the position of the retroreflector 5061 through the displacement module 5062, the optical path of the first sub-beam can be adjusted.

[0100] In one exemplary embodiment, the laser processing apparatus further includes a beam scaling mechanism.

[0101] The beam scaling mechanism is deployed in the optical path of the laser beam emitted by the ultrashort pulse laser and on the light-inlet side of the beam splitting module to adjust the beam size of the cross-section of the incident laser beam along the incident direction.

[0102] A beam scaling mechanism can refer to an optical device capable of adjusting the cross-sectional area of ​​a laser beam along its transmission direction. It is typically used to increase or decrease the cross-sectional area of ​​the beam and can include a beam expander or beam reducer. A beam scaling mechanism can change the collimation and spot size of the beam while maintaining beam quality, ensuring minimal wavefront distortion, and can also modulate the diffraction-free distance of Bessel shaping and the spot size of the Bessel laser beam.

[0103] In one exemplary embodiment, an aperture can also be deployed on the light-inlet side of the beam splitter module to block stray light, reduce glare and ghosting, and improve imaging quality.

[0104] In some feasible implementations, the aperture can be deployed on the output side of the beam expander. In this way, the beam diameter can be increased by the beam expander to reduce the divergence angle, and then the aperture can be used to cut off the uniform central portion to ensure beam quality.

[0105] In one exemplary embodiment, the number of sub-beams is two, including a first sub-beam and a second sub-beam;

[0106] The beam splitting module includes a polarization beam splitter, which is used to split the incident laser beam into a first sub-beam and a second sub-beam.

[0107] It should be noted that although a beam splitter can split an incident laser beam into multiple sub-beams, in practical applications, it is usually chosen to split it into two beams. This is mainly based on considerations of practicality and technical requirements. On the one hand, splitting the beam into two makes the optical structure and control method of the system simpler and more reliable; on the other hand, by controlling the two sub-beams to arrive at the same processing position sequentially, it is possible to ensure that the modified region meets the requirements of subsequent processing while ensuring processing quality and reliability.

[0108] It should be noted that in application scenarios that require more sub-beams, this application can also generate multiple laser beams through beam splitting technology to adapt to the actual needs of different application scenarios and provide a more flexible processing solution.

[0109] A polarization beam splitter is an optical element capable of splitting or combining incident light beams based on their polarization characteristics. A polarization beam splitter can separate an unpolarized or mixed-polarized beam into two orthogonal linearly polarized beams, such as P-polarized and S-polarized beams. It can also combine two orthogonal polarized beams into a single beam. Polarization beam splitters have high energy efficiency; after a laser beam is incident on a deflection beam splitting module, the polarization beam splitter can almost evenly distribute all the energy of the laser beam into the two sub-beams, effectively reducing energy loss and ensuring subsequent modification effects.

[0110] Furthermore, polarization beam splitters can flexibly control the laser power ratio of the two sub-beams after splitting by adjusting the polarization direction of the incident laser beam. Therefore, polarization beam splitters have significant advantages in applications requiring dynamic adjustment of laser power distribution.

[0111] Understandably, other types of laser beam splitting components without polarization capabilities can also be used in beam splitting modules, such as ordinary cubic beam splitters or thin-film beam splitting modules. These beam splitting elements have simple structures and low costs, and can meet application requirements without needing to adjust the laser power of the split sub-beams.

[0112] In an exemplary embodiment, the laser processing apparatus further includes a first beam splitting fine-tuning mechanism, which is disposed on the incident optical path of the polarization beam splitter and is used to modulate the polarization direction of the incident laser beam incident on the polarization beam splitter to adjust the laser power of the first sub-beam and the second sub-beam.

[0113] The first beam splitting fine-tuning mechanism can refer to an optical component capable of adjusting the laser power distribution of the split beam, including at least one of a half-wave plate, a quarter-wave plate, etc. The transmission optical path of each sub-beam is provided with a first beam splitting fine-tuning mechanism, which can be used to further finely control the laser power distribution of the first and second sub-beams after beam splitting by the beam splitting module.

[0114] When a half-wave plate is used as the first beam splitting fine-tuning mechanism, the laser power distribution of each sub-beam can be continuously adjusted by rotating the half-wave plate. When a quarter-wave plate is used as the first beam splitting fine-tuning mechanism, the quarter-wave plate can only achieve 5:5 equal power splitting of the two sub-beams, and cannot dynamically adjust the laser power distribution of the sub-beams through the first beam splitting fine-tuning mechanism.

[0115] For example, the laser power of the first sub-beam and the second sub-beam can be allocated according to the processing requirements. Then, the target polarization direction of the incident laser beam can be determined based on the laser power allocation results of the first and second sub-beams. Subsequently, the polarization direction of the incident laser beam can be modulated to the target polarization direction by rotating a half-wave plate. In this way, after the incident laser beam with the target polarization direction is further incident on a polarization beam splitter for polarization splitting, the first sub-beam and the second sub-beam that meet the processing requirements can be formed.

[0116] It is understandable that in scenarios where there is no need to adjust the intensity of the sub-beams, there is no need to set up a first beam fine-tuning mechanism.

[0117] In some feasible implementations, the first beam splitting fine-tuning mechanism can be a half-wave plate.

[0118] A half-wave plate is a phase delayer based on birefringence. It introduces a π-radian phase difference into the two orthogonally polarized components of the incident light, thereby altering the polarization state of the incident light. By modulating the polarization direction of the laser beam incident on the beam splitter, the laser power distribution between the first and second sub-beams is adjusted.

[0119] By setting a half-wave plate in the incident light path of the beam splitter, the polarization direction of the incident laser beam can be changed by rotating the half-wave plate. This allows adjustment of the ratio of two types of polarized light with mutually perpendicular polarization directions entering the polarization beam splitter, thereby controlling the intensity ratio of the two sub-beams output by the polarization beam splitter and achieving adjustable laser power distribution.

[0120] In one exemplary embodiment, the laser processing apparatus further includes a second beam splitting fine-tuning mechanism disposed on the transmission optical path of at least one sub-beam to adjust the laser power of at least one sub-beam.

[0121] The second beam splitting fine-tuning mechanism can refer to an optical component capable of adjusting the distribution of laser power in a split beam, including at least one of a half-wave plate, a quarter-wave plate, etc. By distributing a second beam splitting fine-tuning mechanism along the optical path of at least one sub-beam, the laser power of each sub-beam can be further fine-tuned, thereby obtaining a laser beam that meets the processing requirements.

[0122] In one exemplary embodiment, the optical path difference is used to ensure that the time difference between the arrival of each sub-beam on the substrate being processed falls within a time range where the electron and exciton concentrations are above a preset concentration threshold.

[0123] When a laser pulse interacts with a material, the material undergoes multiphoton absorption and avalanche ionization, generating a large number of free electrons. These free electrons then undergo relaxation, simultaneously generating excitons within the material. Higher concentrations of free electrons and excitons result in higher light absorption efficiency. If a second laser beam is incident at the point of highest free electron and exciton concentration, the affected region can absorb light energy more effectively, thus forming a more pronounced modified region.

[0124] Therefore, a preset concentration threshold that can be achieved by testing, and the light absorption efficiency can meet the requirements, can be determined in advance. The time range during which the electron and exciton concentrations are higher than the preset concentration threshold can also be determined by testing. Then, based on this time range and the laser propagation speed, the corresponding optical path difference range can be calculated.

[0125] Based on the same inventive concept, this application also provides a pulse modulation device. The solution provided by this pulse modulation device is similar to the solution described in the laser processing device above. Therefore, the specific limitations of one or more pulse modulation device embodiments provided below can be found in the limitations of the laser processing device above, and will not be repeated here.

[0126] In one exemplary embodiment, such as Figure 6 As shown, a pulse modulation device is provided, wherein the modulated laser beam is used to process a transparent solid substrate. The device includes:

[0127] The beam splitting module 602 is deployed in the optical path of the incident laser beam emitted by the ultrashort pulse laser to split the incident laser beam into multiple sub-beams;

[0128] The optical path difference adjustment module 604 is deployed on the light output side of the beam splitting module 602. After at least one sub-beam passes through the optical path difference adjustment module 604, the optical path difference generated between each sub-beam is adjusted.

[0129] The beam combining module 606 is deployed on the common transmission optical path of each sub-beam after the light-emitting side of the optical path difference adjustment module 604. After passing through the beam combining module 606, each sub-beam is incident on the same processing position on the light-transmitting solid substrate at different times and along the same optical path.

[0130] like Figure 7As shown, the laser processing device includes a collimator beam expander 710, an adjustable aperture 712, a 1030nm polarization beam splitter 704, a 1030nm half-wave plate 7141, a dielectric film mirror 716, a hollow right-angle mirror 706, a precision displacement platform 720, a polarization beam combiner 708, and a Bessel shaping module 718.

[0131] An ultrashort pulse laser 702 outputs a 1030nm femtosecond pulse laser beam. The ultrashort pulse laser beam is modulated to a suitable beam diameter by a collimator and expander 710, and then partially filtered out by an adjustable aperture 712. The laser beam passing through the adjustable aperture has its polarization state adjusted by changing the rotation angle of a half-wave plate 7141, thereby controlling the laser power distribution of the two sub-beams output by the polarization beam splitter 704. The laser beam passing through the half-wave plate 7141 is split into two sub-beams by the polarization beam splitter 704: a p-polarized transmitted light and an s-polarized reflected light. The transmitted light passes sequentially through a mirror group consisting of the half-wave plate 7142 and three mirrors 716 before entering the polarization beam combiner 708. The mirror group consisting of the three mirrors 716 ensures that the optical paths of the transmitted and reflected light are completely symmetrical. The reflected light enters first... The light is directed onto a hollow right-angle mirror 706, which is mounted on a precision displacement platform 720. The precision displacement platform 720 can drive the hollow right-angle mirror 706 to move along the direction of the arrow to adjust the optical path of the reflected light according to actual needs. After the optical path of the reflected light is adjusted by the hollow right-angle mirror 706, it passes through a half-wave plate 7143 and then enters a polarization combiner 708. After traveling through propagation paths of different lengths, the transmitted light and the reflected light arrive at the beam combining module one after the other and are combined into the same optical path by the polarization combiner 708. After passing through the beam combining module, the transmitted light and the reflected light pass through two mirrors 716 one after the other, and after their directions are adjusted, they enter a Bessel shaping module 718. The Bessel shaping module 718 consists of a conical lens and a beam compression system, which can convert the ultrashort Gaussian pulse into an ultrashort micro Bessel pulse that meets the processing conditions.

[0132] The half-wave plate 7141 before the polarization beam splitter 704 is used to regulate the laser power distribution of the two sub-beams output by the polarization beam splitter 704. The half-wave plates 7142 and 7143 after the polarization beam splitter 704 are used to further fine-tune the laser power of each sub-beam to obtain a laser beam that meets the processing requirements.

[0133] After processing using the aforementioned temporal and spatial shaping techniques, the spatiotemporal morphology of the laser pulse is as follows: Figure 8 As shown, Figure 8 a represents the light intensity distribution at the waist of the ultrashort micro Bessel pulse in the spatial domain; Figure 8b represents the time distribution of the ultrashort micro Bessel pulse in the time domain, and its delay interval can be adjusted by controlling the displacement of the hollow right-angle mirror 706 through the precision displacement platform 720.

[0134] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps.

[0135] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0136] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A laser processing apparatus characterized by comprising: The laser processing device includes: An ultrashort pulse laser is used to emit an incident laser beam. A beam splitting module is deployed in the optical path of the incident laser beam emitted by the ultrashort pulse laser to split the incident laser beam into multiple sub-beams; An optical path difference adjustment module is deployed on the transmission optical path of at least one of the sub-beams after the light output side of the beam splitting module. After passing through the optical path difference adjustment module, the optical path difference generated between each of the sub-beams is adjusted. A beam combining module is deployed on the common transmission optical path of each of the sub-beams after the light-emitting side of the optical path difference adjustment module. After passing through the beam combining module, each of the sub-beams is incident on the same processing position on the substrate to be processed at different times and along the same optical path.

2. The laser processing apparatus according to claim 1, characterized by The substrate to be processed is a light-transmitting solid substrate; the laser processing device further includes: A Bessel shaping module is deployed on the light-emitting side of the beam combining module. After each sub-beam passes through the Bessel shaping module, it is shaped into a Bessel beam.

3. The laser processing apparatus according to claim 1, characterized by The ultrashort pulse laser includes a femtosecond laser.

4. The laser processing apparatus according to claim 1, characterized by The optical path difference adjustment module includes a retroreflective device, which includes at least one of a hollow right-angle mirror, a hollow roof mirror, and a hollow retroreflector.

5. The laser processing apparatus according to claim 4, characterized by The optical path difference adjustment module further includes at least one displacement module, each displacement module corresponding to each of the retroreflective devices, and each displacement module is connected to its corresponding retroreflective device to adjust the position of its corresponding retroreflective device.

6. The laser processing apparatus according to claim 5, characterized by The number of sub-beams is two, including a first sub-beam and a second sub-beam; The retroreflector is deployed on the transmission optical path of the first sub-beam; the transmission optical path of the first sub-beam also includes a first reflector; through the retroreflector, the first reflector, and the displacement module, an optically path-adjustable first retroreflection optical path is formed on the transmission optical path of the first sub-beam. The laser processing apparatus further includes a mirror group, which is used to form a second retroreflection optical path with a fixed optical path in the transmission optical path of the second sub-beam.

7. The laser processing apparatus according to claim 1, wherein The laser processing apparatus further includes a beam scaling mechanism, which is deployed on the optical path of the incident laser beam emitted by the ultrashort pulse laser and on the light-inlet side of the beam splitting module, for adjusting the beam size of the cross-section of the incident laser beam along the incident direction.

8. The laser processing apparatus according to claim 1, characterized by The number of sub-beams is two, including a first sub-beam and a second sub-beam; The beam splitting module includes a polarization beam splitter, which is used to split the incident laser beam into a first sub-beam and a second sub-beam.

9. The laser processing apparatus according to claim 8, characterized by The laser processing apparatus further includes a first beam splitting fine-tuning mechanism, which is disposed on the incident light path of the polarization beam splitter and is used to modulate the polarization direction of the incident laser beam incident on the polarization beam splitter in order to adjust the laser power of the first sub-beam and the second sub-beam.

10. The laser processing apparatus according to claim 8, characterized by The laser processing device further comprises a second sub-beam fine adjustment mechanism arranged on a transmission light path of at least one of the sub-beams to adjust the laser power of the at least one of the sub-beams.

11. A pulse modulation device, characterized by The modulated laser beam is used for processing a light-transmitting solid substrate, and the pulse modulation device comprises: a beam splitting module arranged on a light path of an incident laser beam emitted by an ultra-short pulse laser, and used for splitting the incident laser beam to form a plurality of sub-beams; an optical path difference adjustment module arranged on a transmission light path of at least one of the sub-beams after the light exit side of the beam splitting module, so that an optical path difference is generated between the sub-beams after passing through the optical path difference adjustment module; a beam combining module arranged on a common transmission light path of the sub-beams after the light exit side of the optical path difference adjustment module, so that the sub-beams are incident on the same processing position of the light-transmitting solid substrate along the same light path at different times after passing through the beam combining module.

Images