Multi-bar series assembly and pumped solid-state laser

Abstract

The present application relates to the technical field of laser devices, and discloses a multi-bar series assembly and a pumped solid-state laser. The multi-bar series assembly comprises a plurality of bar modules which are arranged. Two adjacent bar modules are spaced apart from each other, and a bent and deformable metal foil is connected between the two adjacent bar modules. Positive and negative electrodes of the two adjacent bar modules are electrically connected by means of the metal foil connected between the two adjacent bar modules. By means of the method, the present application allows for effective release of thermal stress in the multi-bar series assembly, eliminates the problem of laser bar cracking caused by use of a hard connection in a conventional structure, improves structural reliability and stability, and prolongs service life.

Description

Dobar strip tandem assembly and pumped solid-state laser Technical Field

[0001] This application relates to the field of laser device technology, specifically to a multibar tandem assembly and a pumped solid-state laser. Background Technology

[0002] In existing semiconductor lasers, multiple bar modules are generally welded together and connected in series by metal blocks to form a multi-bar series assembly. For pump solid-state lasers, in order to achieve the purpose of the bar modules being arranged in a ring or semi-ring, wedge-shaped metal blocks are used to weld together to form a ring or semi-ring multi-bar series assembly. This leads to the problem that the stress cannot be released when multiple bar modules undergo large deformation under high and low temperature cycling.

[0003] In addition, after the bar module generates heat during operation, thermal stress will be generated in the multi-bar series assembly. Since the metal block and the bar module are rigidly connected, the multi-bar series assembly will be subject to large extrusion deformation due to the influence of heat sink deformation. The bar module is prone to displacement, voids or chip breakage due to the large thermal stress that cannot be effectively released, which will ultimately affect the structural reliability, stability and long-term service life of the semiconductor laser. Summary of the Invention

[0004] In view of the above problems, this application provides a multibar tandem assembly and a pumped solid-state laser, which can effectively release the thermal stress in the multibar tandem assembly, improve its structural reliability and stability, and extend its service life.

[0005] According to one aspect of the embodiments of this application, a multi-bar series assembly is provided, including a plurality of bar modules arranged in a row, with adjacent bar modules spaced apart from each other, and a curved and deformable metal foil connecting the adjacent bar modules, wherein the adjacent bar modules achieve positive and negative electrode conductivity through the metal foil connected between them.

[0006] In the multi-bar series assembly provided in this application embodiment, electrical conductivity is achieved by connecting two adjacent and spaced-apart bar modules with a bent metal foil. This allows multiple bar modules to be electrically interconnected. However, due to the gap between adjacent bar modules, stress generated by assembly and thermal expansion or contraction under high and low temperature cycling conditions will concentrate on the metal foil between adjacent bar modules. The bent metal foil has good ductility and deformation capability, so the stress concentrated on the metal foil can be fully released through the deformation of the metal foil. This eliminates the situation where stress is directly applied to the bar chip, solving the problem of bar chip cracking under stress in the bar module. As a result, the structural reliability and stability of the semiconductor laser using this multi-bar series assembly can be improved, and its service life can be extended.

[0007] Furthermore, based on the structure of multiple bar modules connected by flexible and deformable metal foil to form a multi-bar series assembly, when the multi-bar series assembly is used for packaging pump solid-state lasers, the deformation and ductility of the metal foil can be utilized to easily arrange and package multiple bar modules with equal, unequal, or periodically varying spacing according to the layout required by the pump solid-state laser. It is also easy to arrange multiple bar modules in partial rings, semi-rings, or full rings with different radii and package them, thereby meeting the product requirements of various pump solid-state lasers.

[0008] In one alternative approach, the metal foil is U-shaped and welded to the two side bar modules to form surface contact. This arrangement maximizes the contact area between the metal foil and the bar module, minimizing the series resistance at the junction of the bar module and the metal foil, improving conductivity at that point, and providing strong assurance for the operation of the bar module.

[0009] In one alternative embodiment, the portion of the metal foil located between the two bar modules has a bend. When the metal foil is subjected to inward compressive stress, the bend arches further, meaning the radius of curvature of the bend decreases; conversely, when the metal foil is subjected to outward tensile stress, the bend sinks, meaning the radius of curvature of the bend increases. Therefore, by forming a bend in the portion of the metal foil located between the two bar modules, the stress generated in the multi-bar tandem assembly can be better released, thereby further improving structural stability.

[0010] In one alternative approach, multiple bar modules are arranged in an arc shape, and the portion of the metal foil located between the two bar modules is also arc-shaped, consistent with the arrangement of the multiple bar modules. By setting the portion of the metal foil located between the two bar modules to an arc shape consistent with the arrangement direction of the multiple bar modules, the metal foil can redirect more of the laser light reaching its surface towards the crystal rod for secondary reflection, thereby improving the uniformity of light absorption by the crystal rod and enabling the crystal rod to output higher beam quality solid-state laser light.

[0011] In one alternative approach, the metal foil is fixed to the bar modules on both sides by any of the following methods: gold-tin or tin alloy solder welding, laser welding, or resistance welding. Welding with gold-tin or tin alloy solder effectively improves the reliability of the multi-bar series assembly, while laser welding or resistance welding eliminates the need for solder, effectively saving production costs.

[0012] In one alternative approach, the metal foil is any one of copper foil, gold foil, or aluminum foil, wherein copper foil can improve its conductivity while ensuring lower production costs.

[0013] In one optional embodiment, the bar module includes an insulating base and a first connecting substrate, a bar chip, a conductive substrate, and a second connecting substrate disposed on the insulating base; there are multiple bar chips arranged in an array, with adjacent bar chips connected to each other via the conductive substrate for conductivity; the first connecting substrate and the second connecting substrate are respectively disposed on opposite sides of the bar chip at the beginning and the bar chip at the end, with the first connecting substrate connected to the bar chip at the beginning for conductivity, and the second connecting substrate connected to the bar chip at the end for conductivity; in two adjacent bar modules, the second connecting substrate of the preceding bar module and the first connecting substrate of the following bar module are connected to each other via a metal foil for conductivity.

[0014] In one alternative embodiment, both the first and second connecting substrates are made of copper, molybdenum-copper alloy, copper-tungsten alloy, or copper / silver-diamond composite material, so that the thermal expansion coefficients of the first and second connecting substrates are matched with those of the bar chip to minimize the thermal stress generated during operation. Furthermore, the copper, molybdenum-copper alloy, copper-tungsten alloy, or copper / silver-diamond composite material also has high electrical and thermal conductivity to achieve better electrical and thermal conductivity.

[0015] According to another aspect of the embodiments of this application, a pumped solid-state laser is provided, comprising: a crystal rod, a heat sink, and a multi-bar series assembly as described above. Multiple bar modules in the multi-bar series assembly are arranged circumferentially along the crystal rod. The heat sink is disposed on the outer periphery of the multiple bar modules. All multiple bar modules are connected to and insulated from the heat sink. A first electrode is connected to the first bar module, and a second electrode is connected to the last bar module. The first and last modules are interconnected in a positive-negative series configuration. The first and second electrodes are used to connect the positive and negative electrodes of a power supply, so that all bar modules are energized and emit laser light toward the crystal rod. After the crystal rod absorbs the laser light emitted by the bar modules, it outputs a solid-state laser.

[0016] The pumped solid-state laser provided in this application uses the above-mentioned multi-bar series assembly, which enables the stress generated during operation to be fully released through the deformation of the metal foil, thereby eliminating the risk of stress being directly applied to the bar chip in the bar module, solving the problem of bar chip cracking under stress, and thus improving the structural reliability and stability of the pumped solid-state laser and extending its service life.

[0017] In one alternative approach, the portion of the metal foil located between the two bar modules is an arc segment, with the center of the arc segment coinciding with the axis of the crystal rod. This arc segment is used for secondary reflection of the laser light reflected from the crystal rod and reaching its surface back to the crystal rod. By setting the portion of the metal foil located between the two bar modules as an arc segment with its center coinciding with the axis of the crystal rod, the metal foil can reflect more of the laser light reaching its surface towards the crystal rod, thereby improving the uniformity of light absorption by the crystal rod and enabling the crystal rod to output a higher beam quality solid-state laser.

[0018] In one alternative embodiment, the pumped solid-state laser includes at least two multibar tandem assemblies. Multiple bar modules in each multibar tandem assembly are arranged in a partially annular pattern along the circumference of a crystal rod. These multibar tandem assemblies are respectively located on opposite radially opposite sides of the crystal rod, and are at least partially offset along the axial direction of the crystal rod. The heat sink has multiple heat dissipation sections, each located on the outer periphery of one multibar tandem assembly. By arranging each multibar tandem assembly in a partially annular pattern and fixing it with a heat dissipation section on its outer periphery, each multibar tandem assembly and its surrounding heat dissipation section form a unified whole. When the heat dissipation section expands, because it is partially annular, its two free ends move away from each other. Correspondingly, the multiple bar modules within the heat dissipation section move away from each other. This movement, when adjacent bar modules are connected by a metal foil, effectively releases stress between adjacent bar modules through the deformation of the metal foil, ensuring that the bar chips within the bar modules are not compressed, thereby ensuring the structural stability and operational reliability of the bar chips. In addition, by setting multiple bar series components on opposite sides of the crystal rod in the radial direction, and by at least partially misaligning the multiple bar series components along the axial direction of the crystal rod, it is possible to ensure that more bar modules emit laser light into the crystal rod, thus ensuring that the pumped solid-state laser has a high output power.

[0019] In one alternative approach, the bar module is welded and fixed to the metal foil, the bar module to the heat sink, the first bar module to the first electrode, and the last bar module to the second electrode. The melting point of the solder between the bar module and the heat sink, the melting point of the solder between the first bar module and the first electrode, and the melting point of the solder between the last bar module and the second electrode are all lower than the melting point of the solder or the interface layer metal between the bar module and the metal foil, so as to prevent the welding process during the fabrication of the pump solid-state laser from affecting the solder on the already formed multi-bar series assembly.

[0020] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0021] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0022] Figure 1 is a schematic diagram of the structure of a pumped solid-state laser in the prior art;

[0023] Figure 2 is a schematic diagram of the structure of the multibar series assembly with the metal foil openings facing upwards, provided in an embodiment of the present invention.

[0024] Figure 3 is a schematic diagram of the structure of the multibar series assembly with a semi-circular arrangement and the metal foil opening facing upwards, provided in an embodiment of the present invention.

[0025] Figure 4 is a schematic diagram of the structure of the multibar series assembly with the metal foil opening facing upwards, arranged in a ring shape, provided in an embodiment of the present invention.

[0026] Figure 5 is a schematic diagram of the structure of the multibar series assembly with the metal foil openings facing downwards, provided in an embodiment of the present invention.

[0027] Figure 6 is a schematic diagram of the structure of the multi-bar series assembly with a semi-circular arrangement, an upward-facing metal foil opening, and a bent portion on the metal foil provided in an embodiment of the present invention.

[0028] Figure 7 is a schematic diagram of the structure of the multi-bar series assembly provided in an embodiment of the present invention, which is arranged in a ring, with the metal foil opening facing inward and the middle section of the metal foil being arc-shaped.

[0029] Figure 8 is a schematic diagram of the structure of the multi-bar series assembly with a semi-circular arrangement, the metal foil opening facing downwards, and the metal foil having a bent portion provided in an embodiment of the present invention.

[0030] Figure 9 is a schematic diagram of the structure of the multi-bar series assembly provided in an embodiment of the present invention, which is arranged in a ring, with the metal foil opening facing outward and the middle section of the metal foil being arc-shaped.

[0031] Figure 10 is a schematic diagram of the structure of the pumped solid-state laser provided in an embodiment of the present invention;

[0032] Figure 11 is a schematic diagram of the structure of a pumped solid-state laser from one side view according to another embodiment of the present invention;

[0033] Figure 12 is a top-view structural schematic diagram of a pumped solid-state laser provided in another embodiment of the present invention.

[0034] The reference numerals in the detailed embodiments are as follows:

[0035] In Figure 1: 1. Bar module; 2. Wedge block; 3. Solder layer; 4. Heat sink; 5. Crystal rod.

[0036] In other figures: 100, multibar series assembly; 111, insulating base; 112, first connecting substrate; 113, bar chip; 114, conductive substrate; 115, second connecting substrate; 110, bar module; 120, metal foil; 121, bending portion; 122, arc segment; 130, gold-tin solder layer; 200, crystal rod; 300, heat sink; 310, heat dissipation portion; 410, first electrode; 420, second electrode; 500, pump solid-state laser. Detailed Implementation

[0037] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0039] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0040] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0041] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0042] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0043] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0044] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" 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. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0045] Taking a pumped solid-state laser as an example, as shown in Figure 1, the bar module 1 and the wedge block 2 are joined together by the solder layer 3, so that multiple bar modules 1 are connected in series to form a semi-annular multi-bar series assembly. The multi-bar series assembly is fixed on the outer heat sink 4. After the bar modules 1 at both ends are connected to the power supply, the bar chip in the bar module 1 is energized and emits laser in the radial direction (in the direction shown by the dotted arrow in the figure) toward the crystal rod 5 in the middle. After the crystal rod 5 absorbs the laser emitted by the bar chip, it outputs solid-state laser in the axial direction (perpendicular to the plane of the paper shown in Figure 1). This is the structure and working principle of the ring semiconductor laser pumped solid-state laser.

[0046] In order to prevent the relatively fragile bar chip in the bar module 1 from cracking due to high stress, the wedge block 2 and the bar module 1 can be welded with a soft solder with a low melting point. Although the solder layer 3 formed by this soft solder can alleviate the stress on the bar chip to a certain extent through deformation, it is limited by the material properties of the soft solder, such as easy thermal fatigue, easy oxidation and electromigration, which can easily lead to a decrease in the reliability of the laser after long-term operation and a shorter lifespan.

[0047] Taking indium-based alloy solder as an example, the solder is prone to oxidation in high-temperature working environments. After high and low temperature cycling, the thermal fatigue resistance of indium-based alloy solder will decrease. The connection between indium-based alloy solder and wedge block and bar module is also more prone to voids, which will significantly reduce reliability. Moreover, after high and low temperature cycling and under high current density working conditions, arcing of laser bar chip is also likely to occur.

[0048] Furthermore, due to the inconsistency of material processing dimensional accuracy between different wedge blocks 2, when welding the two sides of the wedge block 2 to the bar module 1 to form a ring or semi-ring multi-bar series assembly, the welding distance on both sides of the wedge block 2 is not equal. Therefore, the actual required thickness of the solder is also different. In the actual manufacturing process, the same welding process is generally used in different positions, that is, the amount of solder in different positions is basically equal. This will lead to welding holes or incomplete welds in some welding positions, which will reduce the electrical conduction area of ​​the weld, increase the series resistance, and increase the heat generation accordingly, which may ultimately cause the risk of laser burnout.

[0049] In view of the series of problems caused by connecting the bar modules in series with wedge blocks, this application considers using a deformable structure to connect the bar modules together to form a multi-bar series assembly. The deformation of this structure can release the stress on the multi-bar series assembly, thereby improving the reliability and stability of the laser structure and extending its service life.

[0050] Based on this, embodiments of this application provide a multibar tandem assembly and a pumped solid-state laser including the multibar tandem assembly. The multibar tandem assembly and the pumped solid-state laser including the multibar tandem assembly are, but are not limited to, applications in industrial processing, intelligent manufacturing, material processing, scientific research, medical aesthetics, laser ranging, and other fields.

[0051] Please refer to Figure 2 first, which shows the structure of the multibar series assembly provided in this embodiment of the application. As shown in the figure, the multibar series assembly 100 includes a plurality of bar modules 110 arranged in a row. Adjacent bar modules 110 are spaced apart from each other, and a flexible and deformable metal foil 120 connects adjacent bar modules 110. The positive and negative electrodes of adjacent bar modules 110 are made conductive through the metal foil 120 connecting them.

[0052] It should be noted that in the specific embodiment shown in Figure 2, three bar modules 110 are connected to each other through two metal foils 120 to form a multi-bar series assembly 100 as an example. This does not constitute a limitation on the specific number of bar modules 110.

[0053] Metal foil 120 refers to a thin metal sheet made by stretching metal. Since metal foil 120 has a certain degree of ductility, after connecting two adjacent bar modules 110 by bending metal foil 120, the deformation capability of metal foil 120 can be used to make multiple bar modules 110 arranged in a semi-circular shape as shown in Figure 3, or to make more bar modules 110 arranged in a circular shape as shown in Figure 4. Of course, they can also be arranged in a small semi-circular shape (less than 1 / 2 ring) or a large semi-circular shape (greater than 1 / 2 ring), and there is no specific limitation.

[0054] The metal foil 120 can be made of a material with good ductility, such as aluminum foil, copper foil, gold foil, etc. Since the metal foil 120 is needed between two adjacent bar modules 110 for conduction and for low cost, copper foil with good conductivity is preferred.

[0055] In the multi-bar series assembly 100 provided in this application embodiment, the multiple bar modules 110 are electrically interconnected by connecting adjacent and spaced-apart pairs of them with a bent metal foil 120. Since there is a gap between adjacent bar modules 110, under high and low temperature cycling conditions, stress generated by assembly and thermal expansion or contraction will concentrate on the metal foil 120 between adjacent bar modules 110. The bent metal foil 120 has good ductility and deformation capability, so the stress concentrated on the metal foil 120 can be fully released through the deformation of the metal foil 120, thereby eliminating the risk of stress being directly applied to the bar chip. This solves the problem of bar chip cracking under stress in the bar module 110, thereby improving the structural reliability and stability of the semiconductor laser using this multi-bar series assembly and extending its service life.

[0056] Furthermore, based on the structure of a multi-bar series assembly 100 formed by connecting multiple bar modules 110 through a bendable and deformable metal foil 120, when the multi-bar series assembly 100 is used for packaging pumped solid-state lasers, the deformation and extension capabilities of the metal foil 120 can be utilized to easily arrange and package multiple bar modules 110 with equal spacing, unequal spacing, or a certain periodic variation in spacing, according to the layout required by the pumped solid-state laser. It is also easy to arrange multiple bar modules 110 in a partially ring-shaped, semi-ring-shaped, or fully ring-shaped manner with different radii and package them, thereby meeting the product requirements of various pumped solid-state lasers.

[0057] To ensure the conductivity at the junction between the bar module 110 and the metal foil 120, as shown in Figure 1, the metal foil 120 can be U-shaped and welded to the bar modules 110 on both sides to form surface contact. This arrangement maximizes the contact area between the metal foil 120 and the bar module 110, thereby minimizing the series resistance at the junction of the bar module 110 and the metal foil 120, improving the conductivity at that point, and providing a strong guarantee for the operation of the bar module 110.

[0058] In addition to the U-shaped metal foil 120 shown in Figure 2 having its opening facing upwards, it can also have its opening facing downwards as shown in Figure 5. The two are identical except for the direction of the opening, so the form with the opening facing downwards will not be elaborated on here.

[0059] It is understandable that, for the U-shaped metal foil 120, since the two ends need to be connected to the bar module 110, the part that can provide deformation is the part that bridges between the two bar modules 110.

[0060] During actual operation, the bar module 110 generates a large amount of heat when emitting lasers, causing the multi-bar series assembly 100 to be in a high-temperature environment. When it stops working, the heat is gradually dissipated and the temperature gradually decreases. Based on this, under the high and low temperature cycle environment, the bar module 110 will cyclically expand and contract. This causes the stress on the metal foil 120 to be mainly in the form of inward compression from the two bar modules 110 (the direction of force is shown by arrow a in Figure 3) or outward stretching from the two bar modules 110 (the direction of force is shown by arrow b in Figure 3).

[0061] Based on this, in order to better release stress in the part of the metal foil 120 located between the two bar modules 110, as shown in Figure 6, this part can have a bending portion 121. The bending portion 121 can form only one bend as shown in the figure, or it can form multiple bends in a wavy or sawtooth manner. Thus, when subjected to inward compression or outward stretching stress from the two bar modules 110, the bending portion 121 deforms in the form of curvature change to achieve the purpose of stress release.

[0062] Specifically, as shown in Figure 6 on the left side of the metal foil 120, when the metal foil 120 is subjected to inward compressive stress in the direction of arrow a, the bent portion 121 will arch further in the direction of the dashed arrow, that is, the radius of curvature of the bent portion 121 will decrease. Conversely, as shown in Figure 6 on the right side of the metal foil 120, when the metal foil 120 is subjected to outward stretching stress in the direction of arrow b, the bent portion 121 will sink in the direction of the dashed arrow, that is, the radius of curvature of the bent portion 121 will increase.

[0063] Therefore, in this embodiment, by forming a bending portion 121 on the portion of the metal foil 120 located between the two bar modules 110, the stress generated in the multi-bar series assembly 100 can be better released, thereby further improving the structural reliability and stability.

[0064] When the multibar cascade assembly 100 is used to pump a solid-state laser, the multiple bar modules 110 are arranged in an arc shape. Specifically, it can be a ring as shown in Figure 7, or a semi-ring or partially ring as mentioned above. The laser emitted by the bar chip in the bar module 110 toward the crystal rod 200 (as shown by the solid arrow in Figure 7) cannot be completely absorbed by the crystal rod 200. Instead, a small portion is reflected by the crystal rod 200. A portion of the reflected laser (as shown by the dashed arrow in Figure 7) reaches the surface of the metal foil 120. Since the surface of the metal foil 120 is relatively smooth, in order to enable the metal foil 120 to reflect more of the laser reaching its surface back to the crystal rod 200, thereby improving the uniformity of light absorption by the crystal rod 200, the portion of the metal foil 120 located between the two bar modules 110 can be arranged in an arc shape consistent with the arrangement direction of the multiple bar modules 110, as shown in Figure 7.

[0065] It should be noted here that the “consistent arc” mentioned here does not mean that the arc on the metal foil 120 located between the two bar modules 110 is completely consistent with the arc of the multiple bar modules 110 arranged together, but rather that they are all arcs that surround the crystal rod 200 in the circumferential direction.

[0066] By setting the portion of the metal foil 120 located between the two bar modules 110 on both sides to be an arc shape consistent with the arrangement direction of the multiple bar modules 110, the metal foil 120 can reflect more of the laser light reaching its surface toward the crystal rod 200. The laser light reflected in the secondary reflection is shown by the small dashed arrow in Figure 7. This improves the uniformity of light absorption by the crystal rod 200, enabling the crystal rod 200 to output a solid-state laser with higher beam quality.

[0067] It is understood that the above embodiments, which provide the forming of a bent portion 121 on the portion of the metal foil 120 located between the two bar modules 110, and the setting of the portion of the metal foil 120 located between the two bar modules 110 as an arc shape consistent with the arrangement direction of the plurality of bar modules 110, are also applicable to the U-shaped metal foil 120 with the opening facing downward as shown in FIG. 5. The specific structure is shown in FIG. 8 and FIG. 9, and the principle and related illustrations are consistent with those described in the above embodiments.

[0068] The multibar series assembly 100 provided in this embodiment of the application, after using a bent metal foil 120 to release stress, no longer needs to use soft solder to release stress. Therefore, the welding and fixing between the metal foil 120 and the bar module 110 can be accomplished using gold-tin solder with a melting point of 283°. After welding and fixing, a gold-tin solder layer 130 as shown in FIG. 2 will be formed between the bar module 110 and the metal foil 120. The gold-tin solder can also be replaced with tin alloy solder. Welding and fixing with gold-tin or tin alloy solder can effectively improve the reliability of the multibar series assembly 100. Of course, in some other embodiments, the metal foil 120 and the bar module 110 can also be directly laser welded or resistance welded, which eliminates the need for solder.

[0069] Specifically, a gold-tin solder sheet or a gold-tin film can be prefabricated between the bar module 110 and the metal foil 120, and the two can be welded and fixed by melting the prefabricated gold-tin solder sheet or the prefabricated gold-tin film at high temperature. It should be noted that the gold-tin solder used for welding the bar module 110 and the metal foil 120 is an existing material.

[0070] Please refer to Figure 2. The bar module 110 includes an insulating base 111 and a first connecting substrate 112, bar chips 113, a conductive substrate 114, and a second connecting substrate 115 disposed on the insulating base 111. Multiple bar chips 113 are arranged in an array, with adjacent bar chips 113 connected by the conductive substrate 114 for conductivity. The first connecting substrate 112 and the second connecting substrate 115 are respectively disposed on opposite sides of the first bar chip 113 (the leftmost bar chip 113 in Figure 2) and the last bar chip 113 (the rightmost bar chip 113 in Figure 2). The first connecting substrate 112 is connected to the first bar chip 113 for conductivity, and the second connecting substrate 115 is connected to the last bar chip 113 for conductivity. In two adjacent bar modules 110, the second connecting substrate 115 of the preceding bar module 110 and the first connecting substrate 112 of the following bar module 110 are connected by a metal foil 120 for conductivity.

[0071] The following exemplarily provides a fabrication process for a multi-bar series assembly 100. Specifically, an existing bar chip module can be used, which includes pre-formed bar chips 113 arranged at intervals and a conductive substrate 114. The first connecting substrate 112 and the second connecting substrate 115 can be rectangular substrate blocks with a volume larger than that of the conductive substrate 114, and can be selected from substrate materials that match the coefficient of thermal expansion of the bar chip 113 and have high electrical and thermal conductivity, such as copper-tungsten alloy, copper / silver-diamond composite material, copper, molybdenum-copper alloy, etc. The selected copper-tungsten alloy, copper / silver-diamond composite material, copper, molybdenum-copper alloy, etc., are all existing materials. The insulating base 111 can be made of aluminum nitride ceramic or other insulating materials, such as insulating silicon nitride, silicon carbide, and diamond.

[0072] First, the bar module 110 is formed. Using a pre-designed and processed fixture, the modules are assembled in the following order: first connecting substrate 112 - bar chip module (i.e., the formed bar chip 113 and conductive substrate 114) - second connecting substrate 115 - insulating base 111. Then, a reflow process is used to solder them together with gold-tin or tin alloy solder to form the bar module 110. Gold-tin or tin alloy solder can effectively improve the reliability of the bar module 110.

[0073] After the multiple bar modules 110 are formed, the multi-bar series assembly 100 is formed. Specifically, the multiple bar modules 110, metal foil 120 and gold-tin solder sheet are placed into a pre-designed and processed fixture in any of the layouts shown in Figures 2 to 9. After the gold-tin solder sheet is melted by the reflow process, the metal foil 120 is soldered together with the first connecting substrate 112 and the second connecting substrate 115 to form the multi-bar series assembly 100.

[0074] It should be noted that the materials and welding methods selected in the above manufacturing process are merely illustrative examples and do not constitute a limitation on the materials and welding methods of each component.

[0075] According to another aspect of the embodiments of this application, a pumped solid-state laser is also provided, as shown in Figure 10, which illustrates the structure of the pumped solid-state laser. As shown in the figure, the pumped solid-state laser 500 includes: a crystal rod 200, a heat sink 300, and a multi-bar series assembly 100 as described in any of the above embodiments. Multiple bar modules 110 in the multi-bar series assembly 100 are arranged circumferentially along the crystal rod 200, specifically in a ring shape as shown in Figure 10, or in a semi-ring or partially ring shape. The heat sink 300 is disposed on the outer periphery of the multiple bar modules 110, and the multiple bar modules 110 are all connected to and insulated from the heat sink 300. Specifically, the heat sink 300 can be made of copper or other alloy materials with good thermal conductivity. To further improve thermal conductivity, water or coolant can be circulated within the copper block. The bar modules 110 can be assembled and fixed to the heat sink 300 by their insulating bases 111 to achieve insulation between them.

[0076] A first electrode 410 is connected to the first bar module 110 (the bar module 110 in the upper left of Figure 10), and a second electrode 420 is connected to the last bar module 110 (the bar module 110 in the upper right of Figure 10). The first electrode 410 and the second electrode 420 are positive and negative electrodes, respectively, and are interconnected in a series connection. The first electrode 410 and the second electrode 420 are used to connect the positive and negative electrodes of the power supply (not shown) so that all the bar modules 110 are energized and emit lasers toward the crystal rod 200. After the crystal rod 200 absorbs the laser emitted by the bar modules 110, it outputs solid-state laser.

[0077] The pumped solid-state laser 500 provided in this application embodiment adopts the multi-bar series assembly 100 provided in any of the above embodiments, which realizes that the stress generated during operation can be fully released through the deformation of the metal foil 120, thereby eliminating the situation where the stress is directly applied to the bar chip in the bar module 110, solving the problem of bar chip cracking under stress caused by this, thereby improving the structural reliability and stability of the pumped solid-state laser 500 and extending its service life.

[0078] Further, as shown in Figure 10, the portion of the metal foil 120 located between the two bar modules 110 is an arc segment 122. The center of the arc segment 122 coincides with the axis of the crystal rod 200. The arc segment 122 is used to reflect the laser light reflected from the crystal rod 200 and reaching its surface back to the crystal rod 200. For the specific principle of the secondary reflection of the laser light by the arc segment 122, please refer to Figures 7 and 9 and the description of the relevant principles of Figures 7 and 9 above, which will not be repeated here.

[0079] To increase the power of pumped solid-state lasers, i.e. to enable the crystal rod to receive more laser light, current pumped solid-state lasers typically arrange multiple bar modules in a complete or nearly complete ring (i.e., with a small gap opening) to ensure that more bar modules can be arranged along the circumference of the crystal rod.

[0080] Practical research has revealed that when multiple bar modules are arranged in a complete or nearly complete ring, the outer periphery of these modules is fixed to the same heat sink, and the connection between the modules and the heat sink is rigid. This causes the multiple bar modules to move towards each other when the heat sink expands. However, due to the structural limitations of the solder between adjacent bar modules in the prior art described in Figure 1 above, this tendency to move towards each other will cause the bar chip in the bar module to be subjected to compressive stress, which can easily damage the bar chip.

[0081] To minimize the impact of heat sink 300 expansion on the bar chips in bar module 110 while ensuring high power of pump solid-state laser 500, this application further proposes an implementation method, as shown in Figures 11 and 12. The figures illustrate the structure of pump solid-state laser 500 from a viewpoint at one end of crystal rod 200 and a top viewpoint, respectively. As shown, pump solid-state laser 500 includes at least two multi-bar series assemblies 100. Multiple bar modules in each multi-bar series assembly 100 are arranged in a partially annular pattern along the circumference of crystal rod 200. The multiple multi-bar series assemblies 100 are respectively disposed on opposite radial sides of crystal rod 200, and are at least partially offset along the axial direction of crystal rod 200. Heat sink 300 has multiple heat dissipation portions 310, each heat dissipation portion 310 being disposed on the outer periphery of one multi-bar series assembly 100.

[0082] Specifically, each doba bar series assembly 100 can be arranged in a semi-circular pattern as shown in Figure 11, or it can be arranged in a small semi-circle (less than 1 / 2 circle) or a large semi-circle (more than 1 / 2 circle).

[0083] Multiple doba bar series components 100 are at least partially misaligned along the circumference of the crystal rod 200. This means that when the plane containing the axis of the crystal rod 200 is used as the projection plane, the orthographic projections of any two doba bar series components 100 on the projection plane do not coincide or only partially coincide. In the specific embodiment shown in Figure 11, they do not coincide, while in other embodiments they may partially coincide.

[0084] In this embodiment, each multi-bar series assembly 100 is configured as a partial ring, and a heat dissipation part 310 is provided on its outer periphery to fix it, so that each multi-bar series assembly 100 and its outer periphery heat dissipation part 310 together form an integral whole. For this integral whole, when the heat dissipation part 310 expands, since the heat dissipation part 310 is a partial ring, the two free ends of the heat dissipation part 310 move away from each other. The multiple bar modules 110 on the inner periphery of the heat dissipation part 310 move away from each other accordingly. Under the condition that two adjacent bar modules 110 are connected by metal foil 120, such a movement trend can effectively release the stress between adjacent bar modules 110 through the deformation of the metal foil 120, and can ensure that the bar chip in the bar module 110 is not squeezed, thereby ensuring the structural stability and operational reliability of the bar chip.

[0085] In addition, in this embodiment, by distributing multiple multibar series components 100 on opposite radial sides of the crystal rod 200, and with at least partial misalignment along the axial direction of the crystal rod 200, it is possible to ensure that more bar modules 110 emit laser light into the crystal rod 200, thus ensuring that the pumped solid-state laser 500 has high power. For the packaging of the pumped solid-state laser 500, the bar modules 110 can be welded to the metal foil 120, to the heat sink 300, to the first electrode 410 at the beginning, and to the second electrode 420 at the end. Considering that the multibar series components 100 need to be formed first during the fabrication process, and then the pumped solid-state laser 500 is fabricated using the formed multibar series components 100, therefore, to prevent welding during the fabrication of the pumped solid-state laser 500... The bonding process affects the solder on the already formed multibar series assembly 100. The melting point of the solder used in the fabrication of the pump solid-state laser 500 is lower than that of the solder used in the fabrication of the multibar series assembly 100. That is, the melting point of the solder between the bar module 110 and the heat sink 300, the melting point of the solder between the first bar module 110 and the first electrode 410, and the melting point of the solder between the last bar module 110 and the second electrode 420 are all lower than the melting point of the solder or the interface layer metal between the bar module 110 and the metal foil 120.

[0086] The following exemplarily provides a fabrication process for a pumped solid-state laser 500. Specifically, the bar module 110 in the multibar cascade assembly 100 is welded and fixed to the metal foil 120 using gold-tin or tin alloy solder. After the multibar cascade assembly 100 is formed, the heat sink 300 and the formed multibar cascade assembly 100 are placed into a designed assembly fixture according to a corresponding arrangement. The bar module 110 is welded and fixed to the heat sink 300 using an indium-based solder with a melting point lower than that of gold-tin solder, for example. Then, the first electrode 410 is welded and fixed to the first bar module 110 using indium-based solder, and the second electrode 420 is welded and fixed to the last bar module 110, forming a semiconductor laser array. Finally, the semiconductor laser array is assembled with the crystal rod 200 accordingly to obtain the pumped solid-state laser.

[0087] Of course, the bar module 110 and the metal foil 120, the bar module 110 and the heat sink 300, the bar module 110 at the beginning and the first electrode 410, and the bar module 110 at the end and the second electrode 420 can also be fixed by laser welding or resistance welding, so that welding can be completed without solder.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way.

Claims

1. A multi-bar series assembly, characterized in that, It includes multiple bar modules arranged in an array, with adjacent bar modules spaced apart from each other, and a flexible and deformable metal foil connecting the adjacent bar modules. The positive and negative electrodes of the adjacent bar modules are made conductive through the metal foil connecting them.

2. The multibar tandem assembly according to claim 1, characterized in that, The metal foil is U-shaped and is welded and fixed to the bar modules on both sides to form surface contact.

3. The multibar tandem assembly according to claim 2, characterized in that, The portion of the metal foil located between the two bar modules has a bent section.

4. The multibar tandem assembly according to claim 2, characterized in that, Multiple bar modules are arranged in an arc shape, and the portion of the metal foil located between the two bar modules is in the same arc shape as the arrangement of the multiple bar modules.

5. The multibar tandem assembly according to claim 2, characterized in that, The metal foil is fixed to the bar modules on both sides by welding with gold-tin or tin alloy solder, laser welding, or resistance welding.

6. The multi-bar series assembly according to claim 1, characterized in that, The metal foil is any one of copper foil, gold foil, or aluminum foil.

7. The doba strip series assembly according to any one of claims 1-6, characterized in that, The bar module includes an insulating base and a first connecting substrate, a bar chip, a conductive substrate, and a second connecting substrate disposed on the insulating base. The bar chips are multiple and arranged in an array, with adjacent bar chips connected to each other through the conductive substrate for electrical conductivity; The first connecting substrate and the second connecting substrate are respectively disposed on opposite sides between the first end of the bar chip and the last end of the bar chip. The first connecting substrate is connected to the first end of the bar chip for conduction, and the second connecting substrate is connected to the last end of the bar chip for conduction. In two adjacent bar modules, the second connecting substrate of the first bar module and the first connecting substrate of the second bar module are connected by the metal foil to conduct electricity.

8. The multi-bar tandem assembly according to claim 7, characterized in that, Both the first connecting substrate and the second connecting substrate are made of copper, molybdenum-copper alloy, copper-tungsten alloy, or copper / silver-diamond composite material.

9. A pumped solid-state laser, characterized in that, include: The crystal rod, the heat sink, and the multibar series assembly as described in any one of claims 1-8, wherein a plurality of bar modules in the multibar series assembly are arranged circumferentially along the crystal rod, the heat sink is disposed on the outer periphery of the plurality of bar modules, and the plurality of bar modules are all connected to the heat sink and insulated from the heat sink; A first electrode is connected to the first bar module, and a second electrode is connected to the last bar module. The first and last bars are interconnected in a positive-negative series manner. The first and second electrodes are used to connect the positive and negative electrodes of the power supply so that all the bar modules are energized and emit lasers toward the crystal rod. After the crystal rod absorbs the laser emitted by the bar modules, it outputs solid-state laser.

10. The pumped solid-state laser according to claim 9, characterized in that, The portion of the metal foil located between the two bar modules is an arc segment, the center of which coincides with the axis of the crystal rod. The arc segment is used to reflect the laser light reflected from the crystal rod and reaching its surface back to the crystal rod.

11. The pumped solid-state laser according to claim 9, characterized in that, The pumped solid-state laser includes at least two of the doba bar tandem assemblies, wherein a plurality of bar modules in each doba bar tandem assembly are arranged in a partially annular manner along the circumference of the crystal rod, the plurality of doba bar tandem assemblies are respectively disposed on two radially opposite sides of the crystal rod, and the plurality of doba bar tandem assemblies are at least partially misaligned along the axial direction of the crystal rod. The heat sink has multiple heat dissipation sections, each of which is disposed on the outer periphery of one of the multibar series components.

12. The pumped solid-state laser according to any one of claims 9-11, characterized in that, The bar module is welded and fixed to the metal foil, the bar module is welded to the heat sink, the bar module at the first end is welded to the first electrode, and the bar module at the tail end is welded to the second electrode. The melting point of the solder between the bar module and the heat sink, the melting point of the solder between the bar module at the first end and the first electrode, and the melting point of the solder between the bar module at the tail end and the second electrode are all lower than the melting point of the solder between the bar module and the metal foil.

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