Double-sided cooling of laser diodes

Abstract

Methods, apparatus, and systems for double-sided cooling of laser diodes are provided. In one aspect, the laser diode assembly includes a first heat sink, a plurality of substrates spaced apart from one another on the first heat sink, a plurality of laser diodes, and a second heat sink on the top side of the plurality of laser diodes. Each laser diode includes a corresponding active layer between a first type doped semiconductor layer and a second type doped semiconductor layer. The bottom side of each laser diode is located on a different corresponding substrate of the plurality of substrates. The plurality of laser diodes are electrically connected in series.

Description

Technical Field

[0001] The present application relates to the cooling of laser diodes. Background Art

[0002] High-power semiconductor laser diodes are cooled to maintain low junction temperature, low carrier leakage, and high reliability. The laser diode can be mounted to a heat sink, which helps reduce thermal impedance. Summary of the Invention

[0003] One aspect of the present application features a laser diode assembly, comprising: a first heat sink; a plurality of substrates spaced apart from one another on the first heat sink; a plurality of laser diodes, each laser diode including a corresponding active layer between a first type doped semiconductor layer and a second type doped semiconductor layer, the bottom side of each laser diode being located on a different corresponding substrate of the plurality of substrates, the plurality of laser diodes being electrically connected in series; and a second heat sink on a top side of the plurality of laser diodes.

[0004] In some embodiments, the laser diode assembly includes a plurality of first electrical contact pads located on the second heat sink, each first electrical contact pad being located on a top side of a corresponding laser diode and being in electrical contact with the first type doped semiconductor layer of the corresponding laser diode, at least one first electrical contact pad providing a series electrical connection between adjacent laser diodes.

[0005] In some embodiments, the laser diode assembly includes a plurality of second electrical contact pads on the plurality of substrates, each second electrical contact pad being located on a different corresponding substrate and being in electrical contact with the second type doped semiconductor layer of a corresponding laser diode, the bottom side of the corresponding laser diode being located on the second electrical contact pad.

[0006] In some implementations, a laser diode assembly includes a plurality of vertical electrical contacts, each vertical electrical contact providing a direct electrical connection between a corresponding first electrical contact pad and a corresponding second electrical contact pad.

[0007] In some embodiments, the plurality of vertical electrical contacts and the plurality of laser diodes form a plurality of pairs, each pair being disposed on a different corresponding substrate and including a different corresponding laser diode and a different corresponding vertical electrical contact.

[0008] In some embodiments, for each of the plurality of pairs, the different corresponding laser diodes are separated from the different corresponding vertical electrical contacts on the different corresponding substrates by a first gap. Adjacent first electrical contact pads can be separated from each other on the second heat sink by a second gap, the second gap having substantially the same width as the first gap. The plurality of first electrical contact pads can be aligned with the plurality of pairs such that each second gap is aligned with a different corresponding first gap.

[0009] In some embodiments, at least one of the plurality of first electrical contact pads provides a direct electrical connection between a first vertical electrical contact in a first pair and a first type doped semiconductor layer of a second laser diode in a second pair adjacent to the first pair.

[0010] In some examples, each vertical electrical contact includes a second type doped semiconductor material.

[0011] In some embodiments, the plurality of substrates includes a plurality of first substrates spaced apart from one another in a horizontal direction on a first heat sink. The laser diode assembly may further include a plurality of second substrates spaced apart from one another in a horizontal direction. Each of the plurality of laser diodes may be positioned between a different corresponding first substrate and a different corresponding second substrate in the plurality of second substrates in a vertical direction perpendicular to the horizontal direction. The second heat sink may be located on top of the plurality of second substrates.

[0012] In some embodiments, along the vertical direction, the bottom surface of the bottom side of each laser diode is on the top surface of the different corresponding first substrate, and the bottom surface of the different corresponding second substrate is on the top surface of the top side of the laser diode, and the bottom surface of the different corresponding first substrate is on the top surface of the first heat sink, and the bottom surface of the second heat sink is on the top surface of the different corresponding second substrate.

[0013] In some embodiments, the top surface of the first heat sink and the bottom surface of the second heat sink are substantially flat and parallel to each other, and vertical distances along the vertical direction between the corresponding active layer of each laser diode and the top surface of the first heat sink are different from each other.

[0014] In some embodiments, for each of the plurality of laser diodes, vertical distances along the vertical direction between the bottom surface of different corresponding second substrates and the top surface of different corresponding first substrates are substantially the same as each other, and each of the plurality of laser diodes has substantially the same vertical thickness along the vertical direction, and the vertical thicknesses of different corresponding second substrates along the vertical direction are different from each other, and the vertical thicknesses of different corresponding first substrates along the vertical direction are different from each other.

[0015] In some embodiments, each first substrate and each second substrate comprises a conductive material. The laser diode assembly includes: a plurality of first electrical contact pads on a first heat sink, at least one of the first electrical contact pads providing a first series electrical connection between first adjacent laser diodes through a corresponding adjacent first substrate; and a plurality of second electrical contact pads on a second heat sink, at least one of the second electrical contact pads providing a second series electrical connection between second adjacent laser diodes through a corresponding adjacent second substrate.

[0016] In some embodiments, the first heat sink includes a plurality of first steps continuous with one another, each of the plurality of substrates is located on a different corresponding first step of the plurality of first steps, and the second heat sink includes a plurality of second steps continuous with one another, a different corresponding second step of the plurality of second steps is on the top side of each of the plurality of laser diodes.

[0017] In some embodiments, the laser diode assembly includes a plurality of electrical contact pads, each electrical contact pad being on a different corresponding second step of the second heat sink and electrically contacting the first type doped semiconductor layer on a corresponding laser diode, the different corresponding second step being located on the corresponding laser diode.

[0018] In some embodiments, the laser diode includes a first face and a second face opposite the first face, the first face and the second face are parallel to each other, and the laser diode is configured to emit light from at least one of the first face or the second face.

[0019] Another aspect of the present disclosure features a method of manufacturing a laser diode assembly. The method includes positioning each of a plurality of laser diodes on a different corresponding substrate of a plurality of substrates, each laser diode including a corresponding active layer between a first type doped semiconductor layer and a second type doped semiconductor layer, with a bottom side of the laser diode on the different corresponding substrate; positioning the plurality of substrates on a first heat sink, with each of the plurality of substrates spaced apart from one another on the first heat sink; and positioning a second heat sink on a top side of the plurality of laser diodes.

[0020] In some embodiments, the method includes: forming a plurality of first electrical contact pads on a second heat sink, each first electrical contact pad being located on the top side of a corresponding laser diode and being electrically contacted with a first type doped semiconductor layer of the corresponding laser diode, at least one first electrical contact pad providing a series electrical connection between adjacent laser diodes; forming a plurality of second electrical contact pads on the plurality of substrates, each second electrical contact pad being formed on a different corresponding substrate and being electrically contacted with a second type doped semiconductor layer of a corresponding laser diode, the bottom side of the corresponding laser diode being located on the second electrical contact pad; and forming a plurality of vertical electrical contacts on the plurality of second electrical contact pads, each vertical electrical contact being on a different corresponding second electrical contact pad and being spaced apart from a corresponding laser diode on a different corresponding second electrical contact pad by a corresponding first gap.

[0021] In some embodiments, adjacent first electrical contact pads are spaced apart from each other on the second heat sink by corresponding second gaps, the corresponding second gaps having substantially the same width as the corresponding first gaps. In some embodiments, positioning the second heat sink on the top side of the plurality of laser diodes includes: inserting a plurality of spacers into the corresponding first gaps; and disposing the plurality of spacers in the corresponding second gaps of the plurality of first electrical contact pads such that each first electrical contact pad provides an electrical connection between a vertical electrical contact corresponding to a first laser diode and a first-type doped semiconductor layer of a second laser diode adjacent to the first laser diode.

[0022] In some implementations, the method includes positioning a different corresponding second substrate of a plurality of second substrates on a top side of each laser diode of the plurality of laser diodes, a second heat sink being located on the plurality of second substrates.

[0023] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram showing an example of a laser diode assembly for double-side cooling of a laser diode.

[0025] Figure 2A is a schematic diagram illustrating a system for integrating single-side emission from multiple laser diodes in a laser diode assembly.

[0026] Figure 2B yes Figure 2A Side view of the laser diode assembly.

[0027] Figure 2C It shows the Figure 2A Schematic diagram of a system in which multiple laser emission points of a laser diode assembly are aligned.

[0028] Figure 3 is a schematic diagram illustrating a system for integrating double-sided emission from multiple laser diodes in a laser diode assembly.

[0029] Figure 4 is a schematic diagram showing another example of a laser diode assembly for double-side cooling of a laser diode.

[0030] Figure 5 is a schematic diagram showing another example of a laser diode assembly for double-side cooling of a laser diode.

[0031] Figure 6Ais a schematic diagram illustrating another system for integrating single-side emission from multiple laser diodes in a laser diode assembly.

[0032] Figure 6B yes Figure 6A Side view of the laser diode assembly.

[0033] Figure 6C It shows the Figure 6A Schematic diagram of a system in which multiple laser emission points of a laser diode assembly are aligned.

[0034] Figure 7A is a schematic diagram illustrating another system for integrating double-sided emission from multiple laser diodes in a laser diode assembly.

[0035] Figure 7B It shows the Figure 7A Schematic diagram of a system in which multiple laser emission points of a laser diode assembly are aligned. DETAILED DESCRIPTION

[0036] The output power of a laser diode is largely limited by heat dissipation, which causes the temperature of the laser diode to increase, thereby reducing the reliability and operating efficiency of the laser diode. A heat sink with high thermal conductivity, such as a copper cooler, can be used to keep the laser diode temperature stable during operation. Cooling the laser diode on both sides (i.e., double-sided cooling) rather than cooling it on a single side (i.e., single-sided cooling) can further improve the stability and operating efficiency of the laser diode. However, making electrical contact with a laser diode cooled on both sides can be complicated because the contact pads coupled to the laser diode can be difficult to reach. In addition, double-sided cooling can cause the laser diode to be damaged by the forces applied during mounting.

[0037] Laser diodes have two sides (front and back). In some cases, the laser diode emits laser light only from the front side, and the laser diode can be considered a laser diode with single-sided emission. In some cases, the laser diode emits laser light from both the front side and the back side, and the laser diode can be considered a laser diode with double-sided emission. Double-sided emission allows the extraction of approximately twice the output power compared to single-sided emission without increasing the critical facet loading that can cause catastrophic optical mirror damage (COMD). However, the amount of heat dissipated can also double, which increases cooling requirements.

[0038] Multiple laser diodes can be arrayed or packaged together to scale up output power. However, efficiently and effectively cooling multiple laser diodes in a package can be challenging. Furthermore, extracting the laser beam from both sides of the laser diode without being obstructed by the substrate presents an engineering challenge due to mechanical tolerances.

[0039] Embodiments of the present application provide methods, apparatus, and systems for (active or passive) dual-sided cooling of multiple laser diodes (with single-sided or dual-sided emission), which can significantly scale up output power, improve efficiency, provide simple system configuration, and reduce costs. Embodiments of the present application can also provide a compact laser platform for high-power, high-brightness diode laser modules based on a single emitter, capable of cooling the laser diode chip from both sides and extracting optical power from both sides, thereby achieving at least double the power compared to a package with the same footprint but with single-sided emission.

[0040] In some embodiments, double-sided cooling of multiple laser diodes is achieved by mounting each laser diode on a stepped substrate, followed by bending the mirror for optical stacking in the fast axis. Each laser diode can be mounted p-side down on the substrate, which is then mounted to different steps of a pair of stepped heat sinks. The heat sinks can be cooled conductively or by forced liquid cooling. Each heat sink can be electrically insulated. The laser diodes can be electrically connected in series by simultaneously soldering to patterned conductive pads on one of the heat sinks.

[0041] In some embodiments, dual-sided cooling of multiple laser diodes is achieved by mounting each laser diode on a flat heat sink, followed by optical stacking of the micro-optics in the fast axis. The laser diodes can be mounted on both sides of the flat heat sink, enabling optical stacking in the fast axis via the micro-optics. The heat sink can be cooled by thermal conduction or forced liquid cooling. The heat sink can be made of an electrically insulating material. At least one of the heat sinks can be patterned with conductive pads (or metal plating) on the electrically insulating material, thereby achieving a series electrical connection of the laser diodes after bonding the laser diodes to the patterned conductive pads on the flat heat sink.

[0042] In some embodiments, double-sided cooling of multiple laser diodes is achieved by placing (or sandwiching) each laser diode between substrates of custom thickness. A constant-thickness sandwich can be fabricated by soldering custom-thick substrates to the p-side and n-side of each laser diode. The substrate thickness is designed so that the laser diode is at a different position on the fast axis for each sandwich. Multiple sandwiches can then be packaged between parallel cooling plates, resulting in a stepped arrangement of the laser diodes and optical stacking on the fast axis by bending the mirrors.

[0043] Figure 11 is a schematic diagram illustrating an example of a laser diode assembly 100 for double-sided cooling of a laser diode. The laser diode assembly 100 includes a first heat sink 102, a second heat sink 104, a plurality of substrates 110a, 110b, 110c (collectively referred to as substrates 110 and individually as substrates 110), and a plurality of laser diodes 120a, 120b, 120c (collectively referred to as laser diodes 120 and individually as laser diodes 120). As an example, Figure 1 Three laser diodes 120 are shown. However, a different number of laser diodes may be included in the laser diode assembly 100, for example, 8 or 16. In some examples, the laser diode assembly 100 has dimensions of 40 mm long (along the Z direction), 80 mm wide (along the X direction), and 15 mm high (along the Y direction).

[0044] Each of the first heat sink 102 and the second heat sink 104 may include, for example, an integrated cooling device having one or more integrated internal coolant channels, and a conductive mounting layer separated from the integrated coolant channels by an insulating layer.

[0045] The plurality of substrates 110 are spaced apart from each other in a horizontal direction (e.g., in the X direction) on the first heat sink 102. The bottom side of each laser diode 120 is located on a different corresponding substrate 110. The second heat sink 104 is located on the top side of the plurality of laser diodes 120. The plurality of laser diodes 110 are electrically connected in series in the laser diode assembly 100.

[0046] Each laser diode 120 may be a single emitter configured to emit light. Figure 1 As shown, each laser diode 120 includes a corresponding active layer 122 between a first type doped semiconductor layer (e.g., an N-type layer) 124 and a second type doped semiconductor layer (e.g., a P-type layer) 126. A metal layer (e.g., gold) may be deposited on each semiconductor layer 124, 126 for electrical connection.

[0047] Laser diode 120 includes a front side and a back side, for example, in an XY plane. Laser diode 120 is configured to emit light from at least one side, for example, only from the front side, or from both the front side and the back side. In some embodiments, the back side has a significantly higher reflectivity than the front side, and laser diode 120 is configured to emit light from the front side. In some embodiments, the back side has substantially the same reflectivity as the front side, and laser diode 120 is configured to emit a first light beam from the front side and a second light beam from the back side.

[0048] The emitted light is along the Z direction perpendicular to the surface (one or more). Each laser diode 120 can be in the form of a single-emitter laser diode chip. In some examples, the chip has dimensions of 0.6 mm wide (along the X direction), 0.1 mm high (along the Y direction), and 5 mm long (along the Z direction). The laser diode chip can have a slow axis along the horizontal direction (e.g., the X direction) and a fast axis along the vertical direction (e.g., the Y direction). In some embodiments, the multiple laser diodes 120 form a laser diode array located between the heat sinks 102 and 104. Each laser diode 120 extends along the Z direction. The laser diodes in the laser diode array are distributed along the horizontal direction (e.g., the X direction). The relative mounting surfaces of the heat sinks 102 and 104 can be parallel to each other. The multiple laser diodes 120 can be arranged on substantially the same plane.

[0049] In some embodiments, the laser diode assembly 100 further includes a plurality of first electrical contact pads 106a, 106b, 106c (collectively referred to as the plurality of first electrical contact pads 106 and individually as the first electrical contact pad 106) on the second heat sink 104. The first electrical contact pads 106 can be deposited on the second heat sink 104 by, for example, patterned metallization using a metal such as copper or copper tungsten. In some examples, the first electrical contact pads 106 have a thickness ranging from 0.03 mm to 0.1 mm. Adjacent first electrical contact pads 106 are separated from each other by a physical gap 103 in a horizontal direction (e.g., the X direction) on the second heat sink 104. The plurality of first conductive pads 106 are electrically insulated from each other on the second heat sink 104.

[0050] Each first electrical contact pad 106 is located on the top side of a corresponding laser diode 120 and is in electrical contact with the first type doped semiconductor layer 124 of the corresponding laser diode 120. At least one first electrical contact pad provides a series electrical connection between adjacent laser diodes 120. For example, Figure 1 As shown, first electrical contact pad 106b electrically connects laser diodes 120a and 120b, and first electrical contact pad 106c electrically connects laser diodes 120b and 120c.

[0051] Each substrate 110 is thermally conductive. In some examples, substrate 110 is made of AlN, BeO, or diamond. In some examples, substrate 110 is made of silicon using standard microprocessing equipment and may include microchannels for forced liquid cooling. The length of substrate 110 can have a tolerance of less than 2 μm (e.g., along the Y direction). For example, a precision-machined substrate with a length tolerance of less than 2 μm can be cost-effectively purchased as substrate 110.

[0052] In some embodiments, each substrate 110 is electrically insulating. In some examples, each substrate 110 is deposited with a corresponding conductive layer 112, such as a metal layer. Laser diode 120 can be mounted to the corresponding substrate 110 via conductive layer 112, for example, via eutectic bonding. Conductive layer 112 can be, for example, a bonding layer made of gold or a gold-tin bilayer. Conductive layer 112 serves as a second electrical contact pad located on a different corresponding substrate 110 and electrically contacting the second type doped semiconductor layer 126 of the corresponding laser diode 120. The bottom side of the corresponding laser diode 120 is located on the second electrical contact pad 112.

[0053] In some embodiments, the laser diode assembly 100 further includes a plurality of vertical electrical contacts 114a, 114b, 114c (collectively referred to as a plurality of vertical electrical contacts 114 and individually as a vertical electrical contact 114). Each vertical electrical contact 114 can include, for example, a P-type second-type doped semiconductor material, the same material as the second-type doped semiconductor layer 126 in the laser diode 120. Each vertical electrical contact 114 provides a direct electrical connection between a corresponding first electrical contact pad 106 and a corresponding second electrical contact pad 112. In this manner, adjacent laser diodes 120 can be electrically connected via the corresponding second electrical contact pad 112, the vertical electrical contact 114, and the corresponding first electrical contact pad 106. For example, the laser diodes 120a, 120b are electrically connected sequentially through the second electrical contact pad 112, the vertical electrical contact 114a, and the first electrical contact pad 106b by electrically connecting the P-type layer 126 of the laser diode 120a to the N-type layer 124 of the laser diode 120b.

[0054] In some embodiments, the substrate 110 is electrically conductive. The first heat sink 102 is electrically insulating. Each of the plurality of substrates 110 is electrically insulated from each other. The laser diode 120 and the vertical electrical contact 114 are directly mounted to the corresponding substrate 110 and are electrically conductive to each other through the substrate 110.

[0055] like Figure 1As shown, the plurality of vertical electrical contacts 114 and the plurality of laser diodes 120 form a plurality of pairs. Each pair is disposed on a different corresponding substrate 110 and includes a different corresponding laser diode 120 and a different corresponding vertical electrical contact 114, separated by a physical gap 113. At least one of the plurality of first electrical contact pads 106 provides direct electrical contact between a first vertical electrical contact 114 in a first pair and a first type doped semiconductor layer 124 of a second laser diode 120 in a second pair adjacent to the first pair. Each vertical electrical contact 114 has substantially the same height (in a vertical direction, such as the Y direction) as each laser diode 120. The mounting surfaces of the first heat sink 102 and the second heat sink 104 are substantially flat and parallel to each other, for example, in a horizontal direction, such as the X direction.

[0056] The gaps 113 can have substantially the same width (e.g., along a horizontal direction, such as the X direction) as the gaps 103 between adjacent first electrical contact pads 106. The plurality of first electrical contact pads 106a can be aligned with the plurality of pairs such that each gap 103 is aligned with a different corresponding gap 113. In some embodiments, during fabrication of the laser diode assembly 110, spacers are positioned in the gaps 103 and 113 to place the laser diode 120, substrate 110, and heat sink 104 in corresponding locations.

[0057] The laser diode assembly 100 can be manufactured in such a manufacturing process. In some embodiments, the process includes positioning the bottom side of each of the plurality of laser diodes 120 on a different corresponding substrate in the plurality of substrates 110, positioning the plurality of substrates 110 on a first heat sink 102, with each substrate 110 spaced apart from each other on the first heat sink 102, and positioning the second heat sink 104 on the top side of the plurality of laser diodes 120.

[0058] The process may also include forming a plurality of first electrical contact pads 106 on the second heat sink 104, for example, by patterned metallization. Each first electrical contact pad 106 is located on the top side of a corresponding laser diode 120 and is in electrical contact with the first type doped semiconductor layer 124 of the corresponding laser diode 120. At least one first electrical contact pad 106 provides a series electrical connection between adjacent laser diodes 120.

[0059] The process may further include forming a plurality of second electrical contact pads 112 on the plurality of substrates 110. Each second electrical contact pad 112 may be formed on a different corresponding substrate 110 and electrically contact the second type doped semiconductor layer 126 of a corresponding laser diode 120, with the bottom side of the corresponding laser diode 120 located on the second electrical contact pad 112.

[0060] The process may further include forming a plurality of vertical electrical contacts 114 on the plurality of second electrical contact pads 112. Each vertical electrical contact 114 is on a different corresponding second electrical contact pad 112 and is separated from a corresponding laser diode 120 on the different corresponding second electrical contact pad 112 by a corresponding first gap 113.

[0061] Adjacent first electrical contact pads 106 are spaced apart from each other on the second heat sink 104 by corresponding second gaps 103, the corresponding second gaps 103 having substantially the same width as the corresponding first gaps 113. In some embodiments, positioning the second heat sink 104 on the top side of the plurality of laser diodes 120 includes inserting a plurality of spacers into the corresponding first gaps 113, and disposing the plurality of spacers in the corresponding second gaps 103 of the plurality of first electrical contact pads 106 such that each first electrical contact pad 106 provides an electrical connection between a vertical electrical contact corresponding to a first laser diode 120 and a first type doped semiconductor layer 124 of a second laser diode 120 adjacent to the first laser diode 120. The first electrical contact pads 106 can be bonded to the first type doped semiconductor layer 124 of the first laser diode 120 and the corresponding vertical electrical contact 114.

[0062] Figure 2A-2C A system 200 is shown for integrating single-side emission from multiple laser diodes into a laser diode assembly 230. The laser diode assembly 230 may be Figure 1 The system 200 is configured to combine laser beams emitted from laser diodes into a single optical fiber 220 having an end cap 222.

[0063] The laser diode assembly 230 includes a plurality of laser diode devices 210a, 210b, 210c (collectively referred to as a plurality of laser diode devices 210 and individually as a laser diode device 210) located on a substrate 232. Each laser diode device 210 includes a laser diode mounted on a substrate 214 (e.g., Figure 1 The laser diode 212 (eg, Figure 1 Laser diode 120). The laser diode 212 in each laser diode arrangement 210a, 210b, 210c is configured to emit a corresponding laser beam 211a, 211b, 211c (collectively referred to as a plurality of beams 211 and individually as a beam 211) from a single side of the laser diode, for example, the front side. In other words, the laser diode 212 is a laser diode with single-sided emission.

[0064] The substrate 232 may be a flat substrate so that the light beams 211 emitted from the laser diodes 212 may have the same height. The substrate 232 may be a heat sink, for example, Figure 1The heat sink 102 is used to cool the laser diode 212. In some embodiments, the laser diode 212 is cooled by the heat sink 232 and a second heat sink (not shown) located on the top side of the laser diode 212, such as Figure 1 The second heat sink 104 performs double-sided cooling.

[0065] The light beam 211a, 211b, 211c from each laser diode device 210a, 210b, 210c propagates through a first optical component 202a, 202b, or 202c (referred to as first optical component 202) and a second optical component 204a, 204b, or 204c (referred to as second optical component 204) for beam shaping and is then individually redirected by a corresponding redirection mirror 206a, 206b, 206c. In some embodiments, the first component 202 includes a fast axis collimating (FAC) lens configured to collimate the light beam 211 from the laser diode 212 along the fast axis of the light beam 211. The second component 204 includes a slow axis collimating (SAC) lens configured to collimate the light beam 211 along the slow axis of the light beam 211. The redirecting mirrors 206a, 206b, 206c can be configured at an angle so that the collimated light beams 211a, 211b, 211c are spaced apart in parallel and the beam spots 213a, 213b, 213c of the light beams 211a, 211b, 211c are stacked along one direction (e.g., along the fast axis), as shown in FIG. Figure 2C shown.

[0066] The collimated light beams 211a, 211b, 211c are focused by a focusing component 207 (e.g., an optical lens) to be coupled into an optical fiber 220 via an end cap 222. In some examples, the diameter of the end cap 222 is greater than 1 mm, such as 8 mm. In some examples, the core diameter of the optical fiber 220 is greater than 100 μm, such as 135 μm. The numerical aperture (NA) of the optical fiber 220 can be, for example, 0.15. In some embodiments, an optical retarder 208 (e.g., a polarizer such as a half-wave plate) is disposed between the focusing component 207 and the end cap 222 and is configured to adjust the polarization state of the focused light beam onto the end cap 222.

[0067] Figure 3 is a schematic diagram illustrating a system 300 for integrating double-sided emission from multiple laser diode devices into a laser diode assembly 330. The laser diode assembly 330 may be Figure 1 The system 300 is configured to combine laser beams emitted from a laser diode device having double-sided emission into a laser diode having an end cap 322 (e.g., Figure 2A end cap 222) of a single optical fiber 320 (e.g., Figure 2A in the optical fiber 220).

[0068] Similar to Figure 2A-2B The laser diodes 210, laser diode devices 310a, 310b, 310c (generally referred to as a plurality of laser diode devices 310 and individually referred to as a laser diode device 310) in the laser diode assembly 230 are individually mounted on different corresponding substrates in the laser diode assembly 330. Figure 2A-2B The laser diode device 210 includes the laser diode 210 having single-side emission, and the laser diode of the laser diode device 310 is used for double-side emission and is configured to emit laser beams from the front and back sides.

[0069] like Figure 3 As shown, each laser diode device 310a, 310b, 310c emits first light beams 311a, 311b, 311c (collectively referred to as a plurality of first light beams 311 and individually referred to as a first light beam 311) and second light beams 331a, 331b, 331c (collectively referred to as a plurality of second light beams 331 and individually referred to as a second light beam 331) from the front. Each laser diode device 310a, 310b, 310c can be provided with two heat sinks, such as Figure 1 The heat sinks 102 and 104 shown provide double-sided cooling. The heat sinks can be flat, with mounting surfaces parallel to each other. The laser diode device 310 can have the same height between the mounting surfaces of each heat sink and can emit a beam at substantially the same height.

[0070] The system 300 is configured to integrate a first light beam 311 from the front side of the laser diode device 310 and a second light beam 331 from the back side of the laser diode device 310 onto the end cap 322 of the optical fiber 320. Figure 3 As shown, each first light beam 311a, 311b, 311c propagates through the first optical component 302a, 302b, 302c (eg, Figure 2A The first optical component 202, such as a FAC lens) and the second optical components 304a, 304b, 304c (e.g., Figure 2A and is coupled to a second optical component 204, such as a SAC lens, and is redirected by first redirecting mirrors 306a, 306b, 306c (e.g., Figure 2A The first redirecting mirrors 306a, 306b, 306c can be configured at an angle so that the collimated beam spots of the first light beam 311 are stacked and separated along one direction (such as the Y direction), for example, as shown in FIG. Figure 2C This direction may be along the fast axis of the light beam 311 .

[0071] Each second light beam 331a, 331b, 331c propagates through another first optical component 332a, 332b, 332c (e.g., Figure 2A a first optical component 202 such as a FAC lens) and another second optical component 334a, 334b, 334c (e.g., Figure 2A of the second optical component 204, such as a SAC lens) and is redirected by second redirecting mirrors 336a, 336b, 336c (e.g., Figure 2A The second light beam 331 is reflected by a pair of redirecting mirrors 338 and 340 onto the second surface of the optical combiner 350. The second redirecting mirrors 336a, 336b, 336c can be configured at an angle so that the collimated beam spots of the second light beam 331 are stacked and separated along the direction (such as the Y direction), for example, as shown in FIG. Figure 2C In some embodiments, an optical retarder 352 (e.g., a polarizer) is disposed on the second surface of the prism 350 and is configured to adjust the polarization state of the second light beam 331. The optical combiner 350 can be configured such that the first light beam 311 and the second light beam 331 are redirected in the same direction (such as the X direction) toward the end cap 322 of the optical fiber 320, and are stacked and spaced apart in the Y direction (e.g., along the fast axis).

[0072] Focusing component 307 (eg, Figure 2A The focusing component 207 of the optical retarder 308 is configured to focus the first light beam 311 and the second light beam 331 onto the end cap 322. Figure 2A An optical delay device 208) can be disposed between the focusing component 307 and the end cap 322 and configured to adjust the polarization states of the focused first light beam 311 and the focused second light beam 331.

[0073] Figure 4 is a schematic diagram illustrating another example of a laser diode assembly 400 for double-sided cooling of a laser diode. The laser diode assembly 400 includes a first heat sink 402, a second heat sink 406, and a plurality of laser diodes 410a, 410b, 410c, 410d, 410e, 410f (collectively referred to as a plurality of laser diodes 410 and individually as a laser diode 410). As an example, Figure 4 Six laser diodes 410 are shown in FIG. However, a different number of laser diodes may be included in the laser diode assembly 400. Each laser diode may be Figure 1 The laser diodes 120 are connected in series. Each laser diode can be used for single-side emission or for double-side emission. The laser diodes 410 are electrically connected in series. Each of the first heat sink 402 and the second heat sink 404 can be Figure 1 The first heat sink 102 or Figure 1 The second heat sink 104 is provided.

[0074] Different from Figure 1Each laser diode 120 is located on a single substrate, and each laser diode 410 is disposed between a pair of substrates. Figure 4 As shown, the laser diode assembly 400 includes a plurality of first substrates 420a, 420b, 420c, 420d, 420e, and 420f (collectively referred to as the plurality of first substrates 420 and individually as the first substrate 420) and a plurality of second substrates 430a, 430b, 430c, 430d, 430e, and 430f (collectively referred to as the plurality of second substrates 430 and individually as the second substrate 430). Each laser diode 410 is sandwiched between a corresponding first substrate 420 and a corresponding second substrate 430. Each of the first and second substrates 420 and 430 is electrically and thermally conductive, for example, made of a conductive material such as copper.

[0075] The laser diode assembly 400 further includes a plurality of first electrical contact pads 404a, 404b, 404c (collectively referred to as first electrical contact pads 404 and individually as first electrical contact pads 404) on the first heat sink 402. The first electrical contact pads 404 can be deposited on the first heat sink 402 by, for example, patterned metallization using a metal such as copper or copper tungsten. At least one first electrical contact pad 404 provides a first series electrical connection between each first adjacent laser diode 410 through the conductive corresponding adjacent first substrate 420. For example, Figure 4 As shown, the laser diodes 410a, 410b are electrically connected via the first substrate 420a, the first electrical contact pad 404a, and the first substrate 420b.

[0076] The laser diode assembly 400 also includes a plurality of second electrical contact pads 408a, 408b, 408c (collectively referred to as second electrical contact pads 408 and individually as second electrical contact pads 408) on the second heat sink 406. The second electrical contact pads 408 can be deposited on the second heat sink 406 by, for example, patterned metallization using a metal such as copper or copper tungsten. At least one second electrical contact pad 408 provides a second series electrical connection between each second adjacent laser diode 410 through the corresponding adjacent second substrate 430. For example, Figure 4 As shown, laser diodes 410b and 410c are electrically connected via second substrate 430b, second electrical contact pads 408b, and second substrate 430c. In this manner, laser diodes 410 can be electrically connected in series along a horizontal direction (e.g., along the X direction). Second electrical contact pads, such as 408a and 408d, located at both ends of the plurality of second electrical contact pads can be coupled to a positive voltage (or current) and a negative voltage (or current), respectively, of a power supply.

[0077] The plurality of first substrates 420 are spaced apart from one another in the horizontal direction (e.g., in the X direction) on the first heat sink 402 via first electrical contact pads 404. The plurality of second substrates 430 are spaced apart from one another in the horizontal direction on the second heat sink 406 via second electrical contact pads 408. Each laser diode 410 is positioned vertically between a different corresponding first substrate 420 and a different corresponding second substrate 430. The vertical direction (e.g., the Y direction) is perpendicular to the horizontal direction (e.g., the X direction). The second heat sink 406 is located on top of the plurality of second substrates 430.

[0078] In the vertical direction, the bottom surface of the bottom side of each laser diode 410 is located on the top surface of the first substrate 420, and the bottom surface of the second substrate 430 is located on the top surface of the top side of the laser diode 410. The bottom surface of the first substrate 420 is located on the top surface of the first heat sink 402, and the bottom surface of the second heat sink 406 is located on the top surface of the second substrate 430.

[0079] In some embodiments, the top surface of the first heat sink 402 and the bottom surface of the second heat sink 406 are substantially flat and parallel to each other. The vertical distance between the corresponding active layer of each laser diode 410 and the top surface of the first heat sink 402 in the vertical direction can be different from each other. For example, Figure 4 As shown, the vertical distance may gradually decrease from left to right along the horizontal direction. For each laser diode 410, the vertical distances between the bottom surfaces of the different corresponding second substrates 430 and the top surfaces of the different corresponding first substrates 420 along the vertical direction (e.g., along the Y direction) are substantially the same. Each laser diode 410 may have substantially the same vertical thickness along the vertical direction. The vertical thicknesses of the different corresponding second substrates 430 along the vertical direction are different from each other, and the vertical thicknesses of the different corresponding first substrates 420 along the vertical direction are different from each other. For each laser diode 410, the sum of the vertical thickness of the corresponding first substrate 420 and the vertical thickness of the corresponding second substrate is the same.

[0080] The laser diode assembly 400 can be manufactured by a manufacturing process. In some embodiments, the process includes positioning each laser diode 410 in a plurality of laser diodes on a different corresponding first substrate 420 in a plurality of first substrates, with the bottom side of the laser diode 410 on the different corresponding first substrate 420; positioning the plurality of first substrates 420 on a first heat sink 402, with each first substrate 420 spaced apart from each other on the first heat sink 402; and positioning a second heat sink 406 on the top side of the plurality of laser diodes 410. The process also includes positioning a different corresponding second substrate 430 in a plurality of second substrates on the top side of each laser diode 410 in the plurality of laser diodes, with the second heat sink 406 located on the plurality of second substrates 430.

[0081] The mounting surfaces of the first heat sink 402 and the second heat sink 406 can be substantially flat and parallel to each other. For each of the plurality of laser diodes 410, the total height of the laser diode 410, the corresponding first substrate 420, and the corresponding second substrate 430 is substantially the same. Each of the plurality of laser diodes 410 is in a corresponding plane having a different height.

[0082] Figure 5 is a schematic diagram illustrating another example of a laser diode assembly 500 for double-sided cooling of a laser diode. The laser diode assembly 500 includes a first heat sink 502, a second heat sink 504, a plurality of laser diodes 510a, 510b, and 510c (collectively referred to as the plurality of laser diodes 510 and individually as laser diodes 510), and a plurality of substrates 520a, 520b, and 520c (collectively referred to as substrates 520 and individually as substrates 520). The substrates 520 are spaced apart from one another on the first heat sink 502. The bottom side of each laser diode 510 is located on a different corresponding substrate 520. The laser diodes 510 are electrically connected in series in the laser diode assembly 500.

[0083] Each laser diode 510 may be Figure 1 Each laser diode 510 can be used for single-side emission or for double-side emission. As an example, Figure 5 Three laser diodes 510 are shown in FIG. However, a different number of laser diodes may be included in the laser diode assembly 500. Each substrate 520 may be electrically insulating or conductive. Each substrate 520 may be Figure 1 Each laser diode 510 can be mounted on a corresponding substrate 520 via first electrical contact pads 522a, 522b, 522c (collectively referred to as a plurality of first electrical contact pads 522 and individually referred to as a first electrical contact pad 522). The first electrical contact pad 522 can be Figure 1The electrical contact pads 112 may be configured for eutectic bonding between the laser diode 510 and the substrate 520 .

[0084] Similar to Figure 4 The laser diodes 41 are arranged at different heights along the vertical direction (for example, along the Y direction), and the laser diodes 510 are also arranged at different heights along the vertical direction. Figure 4 The first heat sink 402 and the second heat sink 404 have flat mounting surfaces, and the first heat sink 502 and the second heat sink 504 each have a stepped mounting surface. That is, each of the first heat sink 502 and the second heat sink 504 is a stepped substrate. The first heat sink 502 corresponds to the second heat sink 504.

[0085] like Figure 5 As shown, the first heat sink 502 includes a plurality of first steps that are continuous with one another, and each substrate 520 is located on a different corresponding first step of the first heat sink 502. The second heat sink 504 includes a plurality of second steps that are continuous with one another, and a different corresponding second step of the plurality of second steps is located on the top side of each laser diode 510. The height difference between adjacent first steps can be greater than the total height of the laser diode 510 and the substrate 520. The height difference between adjacent second steps can be the same as the height difference between adjacent first steps. For each laser diode 510, the mounting surfaces of the corresponding first step and the corresponding second step are substantially flat and parallel to each other.

[0086] The laser diode assembly 500 also includes a plurality of second electrical contact pads 508a, 508b, 508c, and 508d (collectively, second electrical contact pads 508 and individually, second electrical contact pads 508). Each second electrical contact pad 508 is located on a different corresponding second step of the second heat sink 504 and is in electrical contact with the first type doped semiconductor layer of a corresponding laser diode 510, with the different corresponding second step being located on the corresponding laser diode 510. The second electrical contact pads 508 can be deposited on the second heat sink 504 by, for example, patterned metallization using a metal such as copper or copper tungsten.

[0087] Adjacent laser diodes 510 are electrically connected via corresponding first electrical contact pads 522 and corresponding second electrical contact pads 508. Since the corresponding first electrical contact pads 522 and the corresponding second electrical contact pads 508 are at different heights in the vertical direction, the laser diode assembly 500 may include vertical electrical contact tabs 524a, 524b, 524c (collectively referred to as a plurality of electrical contact tabs 524 and individually referred to as an electrical contact tab 524) electrically connected to the corresponding first electrical contact pads 522, and vertical electrical contact tabs 506b, 506c, 506d (collectively referred to as a plurality of electrical contact tabs 506 and individually referred to as an electrical contact tab 506). Adjacent electrical contact tabs 524 and 506 are electrically connected. For example, Figure 5 As shown, adjacent laser diodes 510a and 510b are electrically connected via first electrical contact pad 522a, electrical contact tabs 524a and 506b, and second electrical contact pad 508b. In this manner, the laser diodes 510 in laser diode assembly 500 can be electrically connected in series along a horizontal direction, such as along the X direction. Second electrical contact pads, such as 508a and 508d, located at both ends of each second electrical contact pad can be coupled to a positive voltage (or current) and a negative voltage (or current) of a power supply, respectively.

[0088] The laser diode assembly 500 can be manufactured using a manufacturing process. In some embodiments, the process includes positioning each laser diode 510 in a plurality of laser diodes on a different corresponding first substrate 520 in a plurality of substrates, with the bottom side of the laser diode 510 on the different corresponding substrate 520; positioning the plurality of substrates 520 on a first heat sink 502, with each first substrate 520 spaced apart from each other on the first heat sink 502; and positioning a second heat sink 504 on the top side of the plurality of laser diodes 510. The plurality of laser diodes 510 are electrically connected in series in the laser diode assembly.

[0089] The first heat sink 502 is a stepped substrate and includes a plurality of first steps that are continuous with one another. Each of the plurality of base plates 520 is mounted on a corresponding first step of the plurality of first steps. The second heat sink 504 is a stepped substrate and corresponds to the first heat sink 502. The second heat sink 504 includes a plurality of second steps that are continuous with one another. The height difference between adjacent second steps can be the same as the height difference between adjacent first steps. The top side of each of the plurality of laser diodes 510 is attached to a different corresponding second step of the plurality of second steps.

[0090] Each substrate 520 can be electrically insulating. The process can include forming a plurality of first electrical contact pads 522 on the plurality of substrates 520. Each laser diode 510 is mounted on a corresponding substrate 520 via a corresponding first electrical contact pad 522. The process can include forming a plurality of second contact pads 508 on the second heat sink 504, for example, by patterned metallization. The process can also include forming vertical electrical contact tabs 524, 506 for electrically connecting the first electrical contact pads 522 and the second electrical contact pads 508, such that the laser diodes 510 are electrically connected in series in the laser diode assembly 500.

[0091] Figures 6A-6C Another system 600 is shown for integrating single-side emission from multiple laser diodes into a laser diode assembly 630. The laser diode assembly 630 may be Figure 4 Laser diode assembly 400 or Figure 5 The laser diode assembly 500 of the laser diode assembly 630 is arranged at different heights along the vertical direction (eg, the Y direction). The system 600 is configured to combine the laser beams emitted from the laser diodes at different heights into a laser beam assembly having an end cap 622 (eg, Figure 2A end cap 222) of a single optical fiber 620 (e.g., Figure 2A In a single optical fiber 220).

[0092] like Figure 6B As shown, the laser diode assembly 630 includes a plurality of laser diodes 610a, 610b, 610c (collectively referred to as a plurality of laser diodes 610 and individually as a laser diode 610) at different heights in the vertical direction. In some examples, each laser diode 610 may be Figure 4 The laser diode 410 is mounted on a substrate (eg, Figure 4 420) and these substrates are located on a flat substrate, such as Figure 4 In some examples, each laser diode 610 may be Figure 5 The laser diode 510 is mounted on a corresponding substrate (e.g., Figure 5 520), the corresponding substrate is located on a stepped substrate (eg, Figure 5 on different steps of the heat sink 502).

[0093] Each laser diode 610 is configured to emit a corresponding laser beam 611a, 611b, 611c (collectively referred to as a plurality of beams 611 and individually referred to as a beam 611) from a single side, such as the front side, of the laser diode 610. That is, the laser diode 610 is used for single-sided emission. In some embodiments, the laser diode 610 is provided by two heat sinks, such as those located on the top and bottom sides of the laser diode 610. Figure 4 The first and second heat sinks 402 and 406 or Figure 5 The first and second heat sinks 502 and 504 in the embodiment perform double-sided cooling.

[0094] The light beam 611a, 611b, 611c from each laser diode 610a, 610b, 610c propagates through a first optical component 602a, 602b, or 602c (referred to as first optical component 602) and a second optical component 604a, 604b, or 604c (referred to as second optical component 604) for beam shaping, and is then individually redirected by a corresponding redirection mirror 606a, 606b, 606c (collectively referred to as the plurality of redirection mirrors 606 and individually referred to as a redirection mirror 606). In some embodiments, the first component 602 includes a fast axis collimating (FAC) lens configured to collimate the light beam 611 from the laser diode 610 along the fast axis of the light beam 611. The second component 604 includes a slow axis collimating (SAC) lens configured to collimate the light beam 611 along the slow axis of the light beam 611. The redirecting mirror 606 can be configured so that the collimated light beams 611a, 611b, 611c are spaced apart in parallel and stacked along a direction (such as the Y direction), as shown in FIG. Figure 6B The stepped substrate or heat sink enables the light beams 611a, 611b, 611c to propagate in the same direction (eg, X direction) without obstruction.

[0095] The collimated light beams 611a, 611b, 611c are guided by another redirecting mirror 608 and focused by a focusing component 609 (e.g., an optical lens) to be coupled into an optical fiber 620 through an end cap 622. Figure 6C As shown, focused beam spots 613a, 613b, 613c of light beams 611a, 611b, 611c may be vertically stacked on a cross section 621 of an optical fiber 620 along a fast axis (eg, Y direction) for generating high power.

[0096] Figure 7A-7B Another system 700 is shown for integrating double-sided emission from multiple laser diodes into a laser diode assembly. The laser diode assembly may be Figure 4 Laser diode assembly 400 or Figure 5The laser diode assembly 500 is configured such that the laser diodes are located at different heights in the vertical direction (e.g., the Y direction) in the laser diode assembly. The system 600 is configured to combine the laser beams emitted from the laser diodes at different heights into a laser diode assembly having an end cap 722 (e.g., Figure 2A end cap 222) of a single optical fiber 720 (e.g., Figure 2A In a single optical fiber 220).

[0097] Similar to Figure 6A-6B The laser diodes 610, 710a, 710b, 710c (collectively referred to as the plurality of laser diodes 710 and individually as laser diodes 710) are at different heights along the Y direction. In some examples, each laser diode 710 is Figure 4 The laser diode 410 can be mounted on a flat substrate (e.g. Figure 4 One of the plurality of substrates on the heat sink 402) (eg, Figure 4 In some examples, each laser diode 710 may be Figure 5 The laser diode 510 is mounted on a corresponding substrate (e.g., Figure 5 520), the corresponding substrate is located on a stepped substrate (eg, Figure 5 In some embodiments, the laser diode 710 is connected to the heat sink 502 on different steps of the heat sink 502. In some embodiments, the laser diode 710 is connected to the heat sink 502 by two heat sinks located on the top and bottom sides of the laser diode 710, such as Figure 4 The first and second heat sinks 402 and 406 or Figure 5 The first and second heat sinks 502 and 504 perform double-sided cooling.

[0098] Different from Figure 6A-6B The laser diode 610 has a single-side emission, and the laser diode 710 is used for double-side emission and is configured to emit laser beams from the front and back. Figure 7A As shown, each laser diode 710a, 710b, 710c emits a first light beam 711a, 711b, 711c (collectively referred to as several first light beams 711 and individually referred to as a first light beam 711) from the front at a different vertical height, and emits a second light beam 731a, 731b, 731c (collectively referred to as several second light beams 731 and individually referred to as a second light beam 731) at a different vertical height.

[0099] The system 700 is configured to integrate a first light beam 711 from the front side of the laser diode 710 and a second light beam 731 from the back side of the laser diode 710 onto an end cap 722 of an optical fiber 720. Figure 7AAs shown, each first light beam 711a, 711b, 711c propagates through the first optical component 702a, 702b, 702c (e.g., Figure 6A The first optical component 602, such as a FAC lens) and the second optical components 704a, 704b, 704c (e.g., Figure 6A and is coupled to a second optical component 604, such as a SAC lens, and is redirected by first redirecting mirrors 706a, 706b, 706c (e.g., Figure 6A The optical combiner 740 (eg, an optical prism) is reflected by the redirecting mirror 606) onto a first surface of an optical combiner 740 (eg, an optical prism).

[0100] Each second light beam 731a, 731b, 731c propagates through another first optical component 732a, 732b, 732c (e.g., Figure 6A a first optical component 602 such as a FAC lens) and another second optical component 634a, 634b, 634c (e.g., Figure 6A of the second optical component 604, such as a SAC lens) and is redirected by second redirecting mirrors 736a, 736b, 736c (e.g., Figure 6A The optical combiner 740 is reflected by the redirecting mirror 606. In some embodiments, the optical delay 742 (e.g., Figure 3 The optical retarder 352 is disposed on the second surface of the prism 740 and is configured to adjust the polarization state of the second light beam 731. The optical combiner 740 can be configured to redirect the first light beam 711 and the second light beam 731 in the same direction (e.g., Z direction) toward the end cap 722 of the optical fiber 720 and stack and space apart in the Y direction. The focusing component 744 (e.g., Figure 6A The focusing component 609 is configured to focus the first light beam 711 and the second light beam 731 onto the end cap 722. The optical delay 746 (e.g., Figure 2A The optical delay device 208 can be disposed between the focusing component 744 and the end cap 722 and configured to adjust the polarization state of the focused first light beam 711 and the focused second light beam 731. Figure 7B As shown, the focused beam spots 713a, 713b, 713c of the first light beams 711a, 711b, 711c and the focused beam spots 733a, 733b, 733c of the second light beams 731a, 731b, 731c can be vertically stacked on the cross section 721 of the optical fiber 720 along the fast axis (e.g., Y direction) for generating high power.

[0101] A number of embodiments of the present invention have been described. However, it should be understood that various modifications can be made without departing from the spirit and scope of the present invention. Therefore, other embodiments are within the scope of the following claims.

Claims

1. A laser diode assembly comprising: a first heat sink extending in a horizontal direction; a plurality of substrates spaced apart from each other on the first heat sink in a horizontal direction; a plurality of laser diodes, each laser diode comprising a corresponding active layer between a first-type doped semiconductor layer and a second-type doped semiconductor layer, a bottom side of each laser diode being positioned on a different corresponding substrate among the plurality of substrates along a vertical direction perpendicular to a horizontal direction, the plurality of laser diodes being electrically connected in series; a second heat sink on a top side of the plurality of laser diodes; a plurality of first electrical contact pads positioned on the second heat sink in a vertical direction and spaced apart from each other in a horizontal direction; a plurality of second electrical contact pads positioned vertically on top of the plurality of substrates; as well as a plurality of vertical electrical contacts positioned in a vertical direction on top of the plurality of second electrical contact pads, Wherein, for each of the plurality of substrates, a corresponding laser diode and a corresponding vertical electrical contact are respectively positioned on a top surface of a corresponding second electrical contact pad parallel to the horizontal direction.

2. The laser diode assembly according to claim 1, wherein Each first electrical contact pad is positioned on a top side of a corresponding laser diode and is in electrical contact with the first type doped semiconductor layer of the corresponding laser diode, at least one first electrical contact pad providing a series electrical connection between adjacent laser diodes.

3. The laser diode assembly according to claim 1, wherein Each second electrical contact pad is positioned on a different corresponding substrate and is in electrical contact with the second type doped semiconductor layer of a corresponding laser diode, the bottom side of the corresponding laser diode being positioned on the second electrical contact pad. 4 . The laser diode assembly of claim 1 , each vertical electrical contact configured to provide a direct electrical connection between a corresponding first electrical contact pad and a corresponding second electrical contact pad.

5. The laser diode assembly according to claim 1, wherein The plurality of vertical electrical contacts and the plurality of laser diodes form a plurality of pairs, each pair being disposed on a different corresponding substrate and including a different corresponding laser diode and a different corresponding vertical electrical contact.

6. The laser diode assembly according to claim 5, wherein: For each of the plurality of pairs, the different corresponding laser diodes are spaced apart from the different corresponding vertical electrical contacts on the different corresponding substrates by a first gap, wherein adjacent first electrical contact pads are spaced apart from each other on the second heat sink by a second gap, the second gap having substantially the same width as the first gap, and wherein the plurality of first electrical contact pads are aligned with the plurality of pairs such that each second gap is aligned with a different corresponding first gap.

7. The laser diode assembly according to claim 5, wherein: At least one of the plurality of first electrical contact pads provides a direct electrical connection between a vertical electrical contact in a first pair of the plurality of pairs and a first type doped semiconductor layer of a second laser diode in a second pair adjacent to the first pair.

8. The laser diode assembly according to claim 1, wherein Each vertical electrical contact includes a second type doped semiconductor material.

9. The laser diode assembly according to claim 1, wherein: The laser diode includes a first surface and a second surface opposite to the first surface, the first surface and the second surface being parallel to each other, and The laser diode is configured to emit light from at least one of the first surface or the second surface.

10. A laser diode assembly comprising: a first heat sink extending in a horizontal direction; a plurality of first substrates spaced apart from each other on the first heat sink in a horizontal direction; a plurality of laser diodes, each laser diode comprising a corresponding active layer between a first type doped semiconductor layer and a second type doped semiconductor layer, a bottom side of each laser diode being positioned on a different corresponding first substrate among the plurality of first substrates, the plurality of laser diodes being electrically connected in series; a second heat sink on a top side of the plurality of laser diodes; a plurality of second substrates spaced apart from each other in a horizontal direction, wherein each of the plurality of laser diodes is positioned between a different corresponding first substrate and a different corresponding second substrate of the plurality of second substrates in a vertical direction perpendicular to the horizontal direction, wherein a vertical thickness of the different corresponding first substrate in the vertical direction and a vertical thickness of the different corresponding second substrate in the vertical direction are different from each other, wherein a second heat sink is positioned on top of the plurality of second substrates, and wherein each first substrate and each second substrate comprises a conductive material; a plurality of first electrical contact pads on the first heat sink in a vertical direction, at least one first electrical contact pad providing a series electrical connection between first adjacent laser diodes in the plurality of laser diodes through two corresponding adjacent first substrates, each of the at least one first electrical contact pad being in electrical contact with bottom surfaces of the two corresponding adjacent first substrates; and A plurality of second electrical contact pads are provided on the second heat sink in a vertical direction, at least one of the second electrical contact pads providing a series electrical connection between second adjacent laser diodes among the plurality of laser diodes through two corresponding adjacent second substrates, and each of the at least one second electrical contact pad is in electrical contact with top surfaces of the two corresponding adjacent second substrates, the top surfaces of the two corresponding adjacent second substrates being opposite to the top and bottom surfaces of the two corresponding adjacent first substrates.

11. The laser diode assembly according to claim 10, wherein: In the vertical direction, the bottom surface of the bottom side of each laser diode is on the top surface of the different corresponding first substrate, and the bottom surface of the different corresponding second substrate is on the top surface of the top side of the laser diode, and The bottom surface of the different corresponding first substrates is on the top surface of the first heat sink, and the bottom surface of the second heat sink is on the top surface of the different corresponding second substrates.

12. The laser diode assembly according to claim 11, wherein The top surface of the first heat sink and the bottom surface of the second heat sink are substantially flat and parallel to each other, and Wherein, vertical distances along the vertical direction between the corresponding active layer of each laser diode and the top surface of the first heat sink are different from each other.

13. The laser diode assembly of claim 12, wherein: For each of the plurality of laser diodes, vertical distances along the vertical direction between the bottom surface of the different corresponding second substrates and the top surface of the different corresponding first substrates are substantially the same as each other, and Each of the plurality of laser diodes has substantially the same vertical thickness along the vertical direction, the vertical thicknesses of the different corresponding second substrates along the vertical direction are different from each other, and the vertical thicknesses of the different corresponding first substrates along the vertical direction are different from each other.

14. The laser diode assembly of claim 10, wherein: The laser diode includes a first surface and a second surface opposite to the first surface, the first surface and the second surface being parallel to each other, and The laser diode is configured to emit light from at least one of the first surface or the second surface.

15. A method of manufacturing a laser diode assembly, the method comprising: positioning each of the plurality of laser diodes on a different corresponding substrate of the plurality of substrates, each laser diode comprising a corresponding active layer between a first type doped semiconductor layer and a second type doped semiconductor layer, with a bottom side of the laser diode being on the different corresponding substrate; positioning the plurality of substrates on a first heat sink, with each of the plurality of substrates being horizontally spaced apart from one another on the first heat sink; positioning a second heat sink on a top side of the plurality of laser diodes; forming a plurality of first electrical contact pads on the second heat sink; forming a plurality of second electrical contact pads on the plurality of substrates; as well as forming a plurality of vertical electrical contacts on the plurality of second electrical contact pads, Wherein, for each of the plurality of substrates, a corresponding laser diode and a corresponding vertical electrical contact are respectively positioned on a top surface of a corresponding second electrical contact pad parallel to the horizontal direction.

16. The method according to claim 15, further comprising: in, each first electrical contact pad being located on a top side of a corresponding laser diode and being in electrical contact with the first type doped semiconductor layer of the corresponding laser diode, at least one first electrical contact pad providing a series electrical connection between adjacent laser diodes; wherein each second electrical contact pad is formed on a different corresponding substrate and is in electrical contact with the second type doped semiconductor layer of a corresponding laser diode, the bottom side of the corresponding laser diode being located on the second electrical contact pad; and Each vertical electrical contact is on a different corresponding second electrical contact pad and is spaced apart from a corresponding laser diode on the different corresponding second electrical contact pad by a corresponding first gap.

17. The method according to claim 16, wherein: Adjacent first electrical contact pads are spaced apart from each other on the second heat sink by corresponding second gaps, the corresponding second gaps having substantially the same width as the corresponding first gaps, and Wherein positioning a second heat sink on the top side of the plurality of laser diodes comprises: inserting a plurality of spacers into the corresponding first gaps; and The plurality of spacers are positioned in the corresponding second gaps of the plurality of first electrical contact pads such that each first electrical contact pad provides an electrical connection between a vertical electrical contact corresponding to a first laser diode and a first type doped semiconductor layer of a second laser diode adjacent to the first laser diode.

18. The method according to claim 15, wherein The laser diode includes a first surface and a second surface opposite to the first surface, the first surface and the second surface being parallel to each other, and The laser diode is configured to emit light from at least one of the first surface or the second surface.

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