Diode laser

Abstract

In order to produce a diode laser with a laser rod (3), a metal layer (24) of a raised structure with raised points (26) is used, which is located between the n-side (10) of the laser rod and a cover (15). The cavities (28) in the protruding structures are then filled with a cured filler (29) through the at least one filler channel (17). The diode laser according to the utility model can work reliably in pulse operation.

Description

Technical Field

[0001] The utility model relates to a diode laser, which comprises a laser rod arranged between a heat conductor and a cover, the heat conductor and the cover serving as electrical contacts, and a working current is conducted to the laser rod through the electrical contacts. Background Art

[0002] Methods for producing diode lasers are already known, in which the laser bar is soldered to a heat sink on the p-side and contact is made on the n-side via bonding wires, for example from US Pat. No. 5,105,429 A and US Pat. No. 4,716,568 A. A disadvantage is the limited current-carrying capacity of the bonding wires.

[0003] By using a solid cover that can be formed as a second heat conductor, a higher current carrying capacity of the n-side current terminal can be achieved. WO2009143835 and WO2009146683 disclose welding a laser bar between two heat conductors. The welding process can cause stress in the laser bar, which can impair the electro-optical properties. WO2011029846 discloses a method for manufacturing a diode laser without involving a welding process, wherein a first metal layer is used between the first contact surface of the laser bar and the first heat conductor, and a second metal layer is used between the second contact surface of the laser bar and the second heat conductor. These layers can be composed of indium, for example, which leads to material closure during the clamping process. The disadvantage is that very high requirements must be placed on the flatness of the laser bar and the flatness of the connecting surface of the two heat conductors and on the parallelism of the surfaces to be maintained during the assembly process. Deviations in the micrometer range can already lead to large-area hollow spots where there is no material closure. In particular, poor material closure formed at the p-side contact surface of the laser bar can lead to overheating or even burning of the laser bar. In addition, material migration of the indium layer may occur. This may cause the laser to malfunction.

[0004] DE102015002176A1 discloses a method for manufacturing a diode laser, in which the n-side of the laser bar is in contact with a protruding structure. During long-term pulsed operation of the laser bar, these protruding structures may creep. This may impair the long-term stability of the laser during pulsed operation. The utility model can be understood as an improvement to the teaching of DE102015002176A1, which is also disclosed as US20180138664A1, which is explicitly included here. Utility Model Content

[0005] The object of the utility model is to provide a diode laser. The diode laser should be able to operate in long-term pulsed operation. For this purpose, it is necessary to suppress the creep of the soft metal layer in the diode laser. If possible, the laser rod will not experience undesirable mechanical stresses during assembly and operation that could impair the electro-optical properties. The method should be able to tolerate unevenness of the contact surfaces of the laser rod and / or the heat conductor or cover. The p-side contact surface of the laser rod (epitaxial side) facing the heat conductor should have the best possible flatness after assembly. Therefore, the laser rod should have the lowest possible smile value. The failure probability of the diode laser should be low. In addition to the manufacturing method, such an advantageous diode laser will also be described.

[0006] Furthermore, high yields are sought in the production of diode lasers.

[0007] This object is achieved by a method for producing a diode laser, characterized by the following steps:

[0008] a. providing at least one laser bar having a plurality of emitters, which has a first contact surface formed as at least one p-contact on a first side and a second contact surface formed as at least one n-contact on a second side opposite to the first side,

[0009] b. Providing a heat conductor having a first connection surface,

[0010] c. providing a cover having a second connection surface,

[0011] d. manufacturing at least one filling channel in the cover, wherein the filling channel has a filling opening, a supply portion and a capillary portion that tapers gradually relative to the supply portion, and the capillary portion terminates at the second connection surface,

[0012] e. providing a second metal layer having a protrusion structure having a plurality of protrusions formed as discrete protrusion points in a cross-sectional plane,

[0013] f. The laser rod is disposed between the heat conductor and the cover, wherein the first contact surface faces the first connection surface of the heat conductor, the second contact surface faces the second connection surface of the cover, and the second metal layer is at least sectionally disposed between the second connection surface and the second contact surface,

[0014] g. generating at least one force having a component pressing the cover in the direction of the heat conductor, wherein, under the effect of the force, the first contact surface is pressed flat against the first connection surface, wherein the second metal layer undergoes a deformation at least in sections in the region of the raised point, and wherein a capillary gap is formed between the second contact surface and the second connection surface between the protrusions, wherein,

[0015] The capillary gap has a smaller hydraulic diameter than the capillary portion,

[0016] h. Establish mechanical connection between cover and heat conductor,

[0017] i. filling the supply portion with a viscous curable filler,

[0018] j. Make the filler pass through the capillary section,

[0019] k. Diffuse the filler into the capillary gap through capillary force,

[0020] 1. Curing the filler, in particular by thermal curing and / or chemical curing.

[0021] Steps f to i can advantageously be performed in a specified order relative to the start of the corresponding step. Advantageously, the filling can last for a shorter time than the expansion of the filler in the capillary gap. The filling time can be less than one tenth of the time of the expansion of the filler in the capillary gap. If the filler does not flow further, it can be considered that the expansion of the filler in the capillary gap has been completed. For this reason, the capillary gap can be at least partially defined by an edge that serves as a tearing edge and prevents overflow. Then, the passage of the filler through the capillary portion is also stopped at the same time.

[0022] By this method, a diode laser according to the utility model can be manufactured, comprising at least one edge-emitting laser bar, the edge-emitting laser bar comprising a plurality of emitters, the emitters having a first contact surface formed as a p-contact and a second contact surface formed as an n-contact, having a normal line n and an area A, a heat conductor having a first connection surface, a cover having a second connection surface, and a second metal layer, wherein the laser bar is arranged between the heat conductor and the cover, and the second metal layer is at least sectionally arranged between the second connection surface and the second contact surface, wherein the cover is mechanically connected to the heat conductor, and the first contact surface is flatly thermally and electrically connected to the first connection surface, and the second contact surface The cover is electrically connected to the second connection surface through a second metal layer, wherein the second metal layer has a connection point at which the second contact surface is continuously connected to the second connection surface in the direction of the normal n, and also has an interruption point at which the second contact surface is discontinuously connected to the second connection surface in the direction of the normal n, wherein the interruption point has a total area equal to at least 50% of the area A, and the interruption point forms a gap, and the gap is filled with at least 80% of the solidified filler, and the cover has at least one filling channel, wherein the filling channel has a filling opening, a supply portion and a capillary portion that is gradually tapered relative to the supply portion, and the capillary portion terminates at the second connection surface.

[0023] Advantageously, the total area of ​​the interruption points may be less than 85% of the area A.

[0024] The method according to the utility model can be advantageously used to manufacture diode lasers designed for high operating currents. The method can tolerate unevenness of the contact surface of the laser rod and / or the heat conductor or the cover. The method according to the utility model ensures that the positive facet of the laser rod, in particular the emitter of the laser rod, is reliably kept free of fillers. Fillers that accidentally reach the vicinity of the emitter can cause irreversible damage to the laser rod. Since this can be avoided in the method according to the utility model, a high yield can be achieved in the manufacture of the laser. The p contact surface of the laser rod facing the heat conductor has a particularly good flatness after assembly. Therefore, the laser rod can have a smile value as low as possible, making it very suitable for beam shaping. In addition, the problem of migration of welding material of the p-side metal layer and migration of protruding structure material of the second metal layer on the n-side can be avoided. The assembly of the laser rod is mechanically low-stress. Therefore, excellent electro-optical properties such as high polarization degree, uniform near-field distribution of laser radiation and high steepness of the power current characteristic curve can be achieved. In addition, the p-side current input can be improved. These favorable characteristics of the diode laser are guaranteed by the filler for a long time. The method according to the invention ensures a reliable and reproducible assembly of a diode laser.

[0025] The diode laser according to the utility model is a device for emitting laser radiation, which has a laser bar as a radiation source. The laser bar can be formed as an edge-emitting diode laser bar in a known manner and includes one or preferably multiple emitters, each of which can be offset relative to each other in the y direction. The laser bar can preferably have a width between 0.3mm and 12mm in the y direction. It can preferably have 1 to 49 emitters. The thickness of the laser bar in the z direction can preferably be between 0.05mm and 0.2mm. The length of the emitter of the laser bar in the x direction can preferably be between 0.5mm and 6mm. The direction of the central beam of the emitted laser radiation can be the x direction. The directions x, y and z can be at right angles to each other. The laser bar can have a known epitaxially produced layer sequence as a pn junction with one or more quantum grooves. The epitaxial layer can be much thinner than the substrate. The thickness of the epitaxial layer can be, for example, between 3μm and 20μm. For example, the thickness of the substrate can be between 50μm and 200μm. A single emitter can preferably be formed as a broadband emitter or a mesh waveguide or a trapezoidal laser. There can also be multiple layer sequences, i.e. multiple pn junctions connected electrically in series. Such a rod is also referred to as a nanostack. In this case, multiple emitters can be stacked one on top of the other in the z direction.

[0026] The facets of the laser bar can be provided with reflectors, for example, a high reflector layer can be applied to the rear facet of the laser element, and a low reflector layer with a reflectivity of, for example, 0.1% to 10% can be applied to the opposite exit side facet containing the exit aperture. The reflectors can define a laser resonator that allows laser operation. However, the laser bar can also be formed as a gain element, which is provided only in conjunction with an external resonator for laser operation. For example, wavelength-dependent feedback can be provided by an external resonator for determining the wavelength of the laser. Such an electro-optical gain element is also understood as a laser bar in the sense of the present invention.

[0027] The laser bar is pumped by current. For example, the operating current may be 1A to 1000A. A first contact surface and a second contact surface are provided on the laser bar for current input. The p-side contact surface may be referred to as a first contact surface. The first contact surface may be an anode of the diode laser bar. The n-side contact surface of the laser bar may be referred to as a second contact surface. The second contact surface may be a cathode of the laser bar. The first and second contact surfaces may each be located in an xy plane. The first contact surface may be arranged on an epitaxial side of the laser bar, which may be referred to as a first side, and the second contact surface may be arranged on a substrate side of the laser bar, which may be referred to as a second side.

[0028] During operation, the laser bar generates waste heat which must be discharged. For this purpose, a heat conductor having a first connection surface is provided. Since the pn junction of the diode laser can be located in the epitaxial layer (i.e. close to the first side) and most of the waste heat can be generated in the pn junction, the heat conductor can preferably be connected to the first side of the laser bar. The first contact surface can be electrically and thermally connected to the first connection surface, and the second contact surface can be electrically connected to the second connection surface.

[0029] The method according to the utility model is used to manufacture a diode laser. For this purpose, a laser rod is provided, which has a first contact surface formed as at least one p-contact on a first side and a second contact surface formed as at least one n-contact on a second side opposite to the first side. The first contact surface can be formed as a contact surface for all emitters. However, it can also be composed of a plurality of separate partial surfaces, which can be separated from each other, such as a partial surface of each emitter. The first contact surface can be, for example, metallization, and the outer layer can be, for example, a gold layer. Preferably, a plating enhanced gold layer with a thickness preferably greater than 0.5 μm, particularly preferably between 1 μm and 10 μm, can be used. The second contact surface can be formed as a contact surface for all emitters. However, it can also be composed of a plurality of separate partial surfaces, such as a partial surface of each emitter. The second contact surface can be, for example, metallization, and the outer layer can be, for example, a gold layer.

[0030] It is also possible to provide a plurality of laser bars which can be arranged, for example, next to each other or one above the other on a heat sink.

[0031] Furthermore, a heat conductor having a first connection surface is provided. The heat conductor can, for example, at least partially consist of copper, aluminum or a copper diamond, aluminum diamond or silver diamond composite material or comprise such a material. For example, it can be designed as a copper body with a composite material inlay. However, it can also, for example, be made completely of copper. The heat conductor can have a metallization, for example Ag / Au or Ni / Au or Ti / Pt / Au, wherein the gold layer is preferably arranged on the outside. The first connection surface can be designed to have a particularly good flatness in order to subsequently obtain a small smile value (deviation of a single emitter from a straight line). Other first connection surfaces can be provided for other laser bars.

[0032] Furthermore, at least one cover with a second connection surface is provided. The cover can be used for electrical contacting of the n-contact of the laser rod. It can also, but not necessarily, be used for heat dissipation. It can consist of a material with good electrical conductivity, for example at least partially of copper, aluminum or a copper diamond, aluminum diamond or silver diamond composite material or include such a material. For example, it can be designed as a copper body with a composite material inlay. However, it can also be made completely of copper, for example. The cover can have a metallization, for example Ag / Au or Ni / Au or Ti / Pt / Au, wherein the gold layer is preferably arranged on the outside.

[0033] At least one filling channel is produced in the cover, wherein the filling channel has a filling opening, a supply portion and a capillary portion which tapers gradually relative to the supply portion and the capillary portion ends at the second connection surface. The filling channel can be designed as a stepped bore.

[0034] According to the utility model, a second metal layer is provided, which has a plurality of protruding points and a plurality of sinking points in a cross-sectional plane. In the sense of the utility model, the layer thickness of the second metal layer may depend on the position. There may be a plurality of protruding points and / or a plurality of sinking points. Those points with the maximum layer thickness in the second metal layer are called protruding points. Therefore, a protruding point is a point that protrudes more from the surface than the surrounding points. From a topographical point of view, the protruding point can be formed as a dome, a platform or a back. The point with the minimum layer thickness in each case is called the sinking point of the layer. From a topographical point of view, the sinking point can in principle be formed as a basin, a depression or a depression. It may be disadvantageous to form a basin or a depression. The layer thickness of the sinking point may be greater than or equal to zero. In the second case, there may be no layer material at the sinking point, so the layer may have an interruption. At the protruding point, the layer thickness may be equal and have a value D. The protruding point can be particularly advantageously formed as a topologically discontinuous surface, i.e., a plurality of partial surfaces. These protruding points can be referred to as protrusions. The depressions can particularly advantageously be formed as topologically continuous surfaces, i.e. depressions (lowlands). The expansion of the filler in the capillary gaps can then be optimal. In a cross-sectional plane that can be perpendicular to the layer plane, multiple protrusions and multiple depressions can be cut. Therefore, the cross-sectional plane can be selected so that it contains the normal to the layer plane. For example, multiple depressions can be seen in such a sectional view. Even when viewed in three dimensions, the points can be formed as continuous surfaces, and the cross-sectional plane can still have multiple depressions in the sense of the present invention. The same applies to the protrusions. It should also be noted that in any desired cross-sectional plane perpendicular to the layer plane, there is no need for multiple protrusions and multiple depressions. For example, multiple protrusions and depressions can be visible in the cross section but not in the longitudinal section.

[0035] In a preferred embodiment, a second metal layer having a plurality of protrusions and a plurality of depressions in a cross-sectional plane is provided by applying a second metal layer as a protrusion structure to a second contact surface or a second connection surface. In this case, the protrusion can be formed as a circular platform with a height of D, which can be imagined as, for example, a cylindrical protrusion, wherein there is no layer material between the protrusions. Such a layer can be manufactured, for example, by a coating process using a hole mask. When considering the three-dimensional topology, the depression of the layer can be a continuous surface. The surface can be considered as a depression. In this case, according to the utility model, the second metal layer can have a plurality of protrusions and a plurality of depressions in the yz cross-sectional plane (cross section). Advantageously, the protrusion structure is formed with a coverage density of at least one protrusion per square millimeter of the surface, particularly advantageously at least 5 protrusions per square millimeter. The distance between adjacent protrusions should not be selected too large, and a maximum distance of 1 mm measured from the edge to the edge of adjacent protrusions may be advantageous. The second metal layer can be different from a conventional solder bump, in particular by a finer structure and a smaller layer thickness.

[0036] According to the utility model, the laser rod is arranged between the heat conductor and the cover, wherein the first contact surface faces the first connection surface of the first heat conductor, the second contact surface faces the second connection surface of the cover, and the second metal layer is at least sectionally arranged between the second connection surface and the second contact surface.

[0037] According to the utility model, at least one force is generated, which has a component that presses the cover in the direction of the heat conductor. This may be the -z direction. Under the action of the force, the first contact surface is pressed flat against the first connection surface. This may result in a clamping connection. Under this contact pressure, unevenness of the second contact surface can be compensated. In this case, the laser rod can be elastically deformed. The second metal layer can undergo plastic deformation at least in sections in the region of the raised points. At these points, the yield limit (extrusion limit) of the layer material may be exceeded. The second contact surface can now be electrically connected to the second connection surface through the second metal layer. At the sinking point, the second metal layer may have a cavity. Therefore, the second metal layer can have a connection point, at which the second contact surface is continuously connected to the second connection surface in the direction of the normal n, and further, at which the second contact surface is discontinuously connected to the second connection surface in the direction of the normal n. The layer normal n can be the normal of the second contact surface, i.e. the z direction. Therefore, the connection point and the interruption point can be projected onto the xy plane. In this case, the interruption point can advantageously have a total area equal to at least 50% of the area of ​​the second contact surface. Taken individually, the interruption points should not be chosen too large to avoid uneven current flow into the second contact surface. In the projection on the xy plane, for each point belonging to the interruption point, the distance to the nearest point belonging to the connection point should not exceed 0.5 mm, advantageously not more than 0.25 mm.

[0038] Furthermore, provision is made for the establishment of a mechanical connection of the cover to the heat conductor. An electrically insulating connection can advantageously be provided so that the laser rod cannot be short-circuited. The connection can be made by means of a bonding agent. For example, an adhesive can be used as bonding agent. Surface bonding with a heat-conducting adhesive can be used particularly advantageously. A spacing or a separation groove can be provided between the laser rod and the bonding surface in order to avoid wetting of the laser rod by the adhesive. The establishment of the mechanical connection can be accompanied by a volume shrinkage of the bonding agent. The mechanical connection can be used to generate and / or retain forces. Thus, a clamped connection of the laser rod between the heat conductor and the cover can also be maintained.

[0039] The second metal layer can be formed as a relief. The layer thickness can depend on the position. The topography of the layer thickness can be constructed in such a way that it can be represented in a single plate projection. The minimum length dimension of the raised point can be considered as a feature size. For example, this can be the diameter of a circular platform or the width of a strip platform. In order to determine the minimum structural size, in general, the contour of the average height between the sinking point and the raised point can be used. For example, the structural size can be the dome diameter at half the dome height or the back width at half the back height. The minimum structural size can advantageously be between 10 μm and 1000 μm. The average contour line can have a total length. In the case of discontinuous average contour lines, the total length should be understood as the sum of the lengths of the individual segments of the average contour line. In other words, under the total length of the average contour line, the sum of the perimeters of the cut surfaces cut on the average contour line can also be considered. The total length L of the average contour line within a given base surface A can be set relative to the base surface, such as the total area of ​​the second metal layer. This ratio, i.e. the quotient L / A, can advantageously be between 1000 m / m2 and 100000 m / m2. If the relief structure is too coarse, i.e. the ratio L / A is too small, the plastic deformation of the second metal layer may be affected. If the relief structure is too fine, i.e. the ratio L / A is too large, the thermal and electrical connection of the laser rod to the heat conductor or the cover may deteriorate over time.

[0040] The second metal layer can be composed of a soft metal, the yield limit (extrusion limit) of which under compressive load is preferably less than 50 MPa, particularly preferably less than 20 MPa or very particularly preferably less than 10 MPa. The second metal layer can be composed of or include a heavy metal, such as tin, lead, indium or cadmium. Indium and / or tin can preferably be used, since lead and cadmium are not very environmentally friendly.

[0041] The plastic deformation of the second metal layer can take place at room temperature without heating. However, heating can also be provided so that the plastic deformation can take place at an elevated temperature. Advantageously, the temperature can be below the liquidus temperature and / or the solidus temperature of the second metal layer. Thus, melting of the second metal layer can be avoided. It has been found that when the second metal layer does not melt, an advantageous more uniform power distribution of the laser radiation over the individual emitters of the laser bar can be achieved.

[0042] The plastic deformation of the second metal layer can occur without volume compression. During the deformation, the thickness of the second metal layer can be reduced in sections at least at the raised points. Excess material can be pressed to the lowered points without the total volume of the material undergoing a significant change. This is not possible for a layer of uniform thickness.

[0043] After the plastic deformation of the second metal layer, an intermetallic phase can be formed at the protruding point of the second metal layer, which limits or prevents further plastic deformation. This intermetallic phase can be produced by diffusion, for example at room temperature or during tempering below the corresponding melting temperature (solidus temperature) of the second layer material and the intermetallic phase. This diffusion process may occur very slowly, for example, it may take several minutes, hours, days, weeks or months. For example, the second connection surface and / or the second contact surface can be designed to be surface-plated with gold. Then, gold can be at least partially diffused into the second metal layer, for example, composed of tin and / or indium. Compared with tin or indium, a very hard gold-tin or gold-indium phase can be formed, which can then no longer be plastically deformed. Since the formation of the intermetallic phase may take a long time, the plastic deformation of the second metal layer according to the utility model will not be affected by force.

[0044] A first metal layer can also advantageously be provided. When the laser bar is arranged, the first metal layer can be arranged at least in sections between the first connection surface and the first contact surface. The first metal layer can have a uniform layer thickness. This can be advantageous, since in this way a better flatness of the p-side of the laser bar can be achieved. The first metal layer can consist of or include a soft heavy metal, for example tin, lead, indium or cadmium. Preferably, indium and / or tin are used, since lead and cadmium are not very environmentally friendly.

[0045] The first or second metal layer may also protrude beyond the first or second contact surface.

[0046] The first and second metal layers can be produced by coating. In manufacturing technology, coating (englisch coating) is understood to be a group of major manufacturing processes according to DIN 8580 for applying an adhesive layer of amorphous materials to the surface of a workpiece. The corresponding process and the applied layer itself are also referred to as coating. The coating can be a thin or thick layer or several interconnected layers, this distinction is not precisely defined and depends on the coating process and the intended use. In the context of the present invention, a coating with a position-dependent layer thickness is also referred to as a layer.

[0047] The second metal layer can be produced by coating the second connection surface. For this purpose, electroplating or physical (e.g. vapor deposition, sputtering) coating processes can be used. Coating can be carried out with a mask to produce depressions and protrusions. Alternatively, a layer of uniform thickness can be applied and then depressions and protrusions can be produced, for example, by embossing, notching or etching. The second metal layer can also be produced by coating the second contact surface of the laser rod.

[0048] The second metal layer can also be designed as a self-supporting layer, which can be produced, for example, by embossing a metal foil.

[0049] The second metal layer can be designed to be thicker than the first metal layer relative to the protruding point. The second metal layer can preferably have a thickness of 3 μm to 100 μm at the protruding point, particularly preferably between 5 μm and 15 μm. The first metal layer can preferably have a uniform thickness of less than 5 μm, particularly preferably less than 3 μm.

[0050] The second metal layer may be applied to the second connection surface. If provided, the first metal layer may be applied to the first connection surface. The second metal layer may be applied to the second contact surface. If provided, the first metal layer may be applied to the first contact surface. Furthermore, further metal layers may be provided between the second contact surface and the second connection surface.

[0051] The second metal layer can have a volume filling degree preferably between 10% and 60% and / or particularly preferably between 10% and 30%. The volume filling degree is to be understood as the ratio of the material volume to the product of the base area D and the layer thickness D of the original (not yet deformed) layer. In this calculation, the layer thickness D is the layer thickness at the protrusion point. Different from this is the second volume filling degree in the assembled state with the deformed second metal layer. The second volume filling degree can be measured after step h. Due to the reduction in layer thickness and the isochoric compression of the protrusion, the second volume filling degree can be larger than the first volume filling degree, for example 1.2 to 5 times larger. However, the second volume filling degree can advantageously be less than 70%, particularly advantageously not more than 50%.

[0052] The utility model also includes a diode laser. According to the utility model, the diode laser includes at least one edge-emitting laser rod, the edge-emitting laser rod having a first contact surface formed as a p-contact and a second contact surface formed as an n-contact, a heat conductor having the first contact surface, a cover having the second contact surface, and a second metal layer. The laser rod is arranged between the heat conductor and the cover. The second metal layer is arranged at least in sections between the second connection surface and the second contact surface. The cover is mechanically connected to the heat conductor. The first contact surface is thermally and electrically connected to the first connection surface of the first heat conductor. This means that through this connection, the best possible heat dissipation of waste heat from the laser rod to the heat conductor is possible, while allowing an electrical connection with the lowest possible resistance for providing the operating current to the laser rod. The second contact surface is electrically connected to the second connection surface through the second metal layer. This means that this connection should also have the lowest possible resistance. The second metal layer has a connection point at which the second contact surface is continuously connected to the second connection surface in the direction of the normal n, that is, in the z direction. In addition, the second metal layer has an interruption point at which the second contact surface is discontinuously connected to the second connection surface in the direction of the normal n. The decisive factor for whether a point on the layer plane is a connection point or an interruption point is whether there is a continuous material closure at this point along the normal direction n or whether there is at least one hollow point in the normal direction n. The layer normal n can be the normal of the second contact surface, i.e. the z direction. Therefore, the connection points and interruption points can be projected onto the xy plane. In this case, the interruption point can advantageously have at least 30% of the area of ​​the second contact surface, particularly advantageously at least 50% of the total area. Taken individually, the interruption point should not be selected to be too large, so as to avoid uneven current flow into the second contact surface. In the projection on the xy plane, for each point belonging to the interruption point, the distance to the nearest point belonging to the connection point should not exceed 0.5 mm, advantageously not more than 0.25 mm.

[0053] Advantageously, the cover can be arranged to contribute to the dissipation of heat from the second contact surface. Hollow points, i.e. interruptions, in the second metal layer are filled in a manner according to the invention. Thus, migration of soft metal material of the protrusions can be avoided. Furthermore, the thermal conductivity can be increased, since the hollow points between the protrusions can contribute to the conduction of heat. The cover can be thermally and mechanically connected to the heat conductor by means of an electrically insulating bonding agent.

[0054] Fillers that can be used are, for example, polyurethanes, epoxy resins, polyester resins, acrylates, elastomers, silicones or mixtures of several of these substances. Alternatively, meltable casting compositions (also called hot melts) can be used, for example those based on polyamide resins, saturated polyesters, ethylene-vinyl acetate copolymers (EVA), block copolymers (for example styrene-butadiene-styrene or styrene-isoprene-styrene), polyimides, polyamides, polyesters, ethylene-vinyl acetate copolymers, vinyl pyrrolidone / vinyl acetate copolymers, polyolefins, shellac or birch pitch. Particularly advantageous meltable fillers are those with a low melting point below 150° C., for example vinyl pyrrolidone / vinyl acetate copolymers or polyethylene. The filler can advantageously be unfilled or equally advantageously used with a filler.

[0055] Inorganic fillers can be particularly suitable as a filler mixture to increase strength and prevent shrinkage during curing, such as carbon black, titanium oxide, chalk, ceramic powder or quartz glass powder. The addition of aluminum nitride, diamond or beryllium oxide powder can also increase the thermal conductivity of the filler. In order to stabilize the filler against laser radiation from the laser rod, it can be advantageous to add a metal deactivator to the filler.

[0056] Curing of the filler can be achieved by chemical curing. For example, a chemical curing reaction of a premixed two-component filler can be used for this purpose. Alternatively or additionally, thermal curing can be performed. For example, epoxy resins or PU potting compounds can be cured by heating to a specified curing temperature. Thermal curing can also be achieved by cooling, for example, if a molten filler, for example based on polyethylene or vinylpyrrolidone / vinyl acetate copolymers, is introduced into a heated diode laser and the diode laser is then cooled, wherein the filler cures.

[0057] The filling opening can advantageously have a filling aid portion which is widened relative to the supply portion. This can be designed as a chamfer. This makes filling with filler easier.

[0058] Advantageously, the filling channel (16) can be formed at an angle between 5° and 45° relative to the normal to the second connecting surface. Thus, the reproducibility of the supply of the partial filling can be improved.

[0059] During filling of the supply section, the filling opening can advantageously be arranged above the capillary section with respect to the force of gravity. Alternatively or additionally, the supply section can be filled starting from the transition section to the capillary section. When filling is carried out in air or under a protective gas atmosphere, bubbles in the filler can be avoided. For this purpose, the filler can be introduced from the filling opening, for example by placing a filler metering needle at the position of the inner wall. Alternatively, the filler can be dripped into each supply section as a single drop. A single falling drop can immediately penetrate the cone without enclosing bubbles in the process.

[0060] Advantageously, the step of filling the supply portion and / or the step of spreading the filling material can be carried out at least temporarily in a vacuum. Thus, air bubbles can be avoided particularly effectively.

[0061] The tapered portion between the supply portion and the capillary portion can be formed as a truncated cone sheath in a jumpy manner, for example as a stepped hole, or in a continuous manner. The latter can be achieved by manufacturing the supply portion with a conically ground drill.

[0062] Advantageously, during the step of spreading the filling, the emitter can be arranged at least temporarily at the top and / or the filling opening can be arranged below the capillary section relative to the earth's gravity. For this purpose, the diode laser can be rotated accordingly after filling. Thus, overflow of the leading edge of the laser rod can be prevented, so that no filling material enters the emitter region.

[0063] Advantageously, during the step of spreading the filler, the diode laser can be at least temporarily exposed to centrifugal forces, in particular centrifugal forces away from the emitter towards the rear facet of the laser rod. Thus, overflow of the leading edge of the laser rod can be reliably prevented, so that no filler enters the emitter region.

[0064] Advantageously, the step of spreading the filling material can be assisted at least temporarily by an oscillating movement and / or by the action of ultrasound on the diode laser and / or by heating the diode laser.

[0065] Advantageously, the viscosity of the filler can be selected such that the Reynolds number in the capillary gap is between 0.005 and 0.1. Thus, a uniform expansion in the capillary gap can be achieved.

[0066] Advantageously, the flow rate of the filler in the capillary gap may be between 0.1 mm / min and 5 mm / min.

[0067] Advantageously, the supply portion may be as long as or longer than the capillary portion.

[0068] Advantageously, the supply portion may be filled with at least three times the volume of the filler compared to the volume of the capillary gap.

[0069] Advantageously, the step of filling the supply portion with the viscous curable filler can be performed after the mechanical connection of the cover to the heat conductor has been established. The diode laser can then reach its mechanical strength before filling.

[0070] Advantageously, there can be exactly two filling channels in the cover. If a channel fails due to clogging, the diode laser can still be successfully manufactured.

[0071] One or more filling channels can advantageously be arranged outside the center of the laser bar. The maximum heat output generated in the center of the bar can then be dissipated without damage. It may be advantageous to arrange one or more filling channels at the edge of the laser bar. Due to the asymmetry, the location in the capillary gap that is farthest from the filling opening can be observed to check complete filling of the capillary gap.

[0072] The hydraulic diameter of the capillary portion may advantageously be between 0.1 mm and 0.4 mm. The diameter of the supply portion may advantageously be between 0.5 mm and 3 mm.

[0073] The use of a second metal layer according to the invention, which is produced using a coating process and has a protrusion structure, wherein the protrusion structure has a coverage density of at least one protrusion per square millimeter of surface, for producing a clamping connection for a diode laser, wherein the second metal layer is arranged between the second n-side contact surface of the laser bar and the second connection surface of the cover, and the second metal layer is arranged on the second contact surface or the second connection surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] In the attached picture:

[0075] Figure 1 The working principle of the first embodiment before assembly is shown;

[0076] Figure 2 The working principle of the first embodiment after assembly is shown;

[0077] Figure 3 The filling of the filler is shown;

[0078] Figure 4 A first embodiment is shown in side view;

[0079] Figure 5 The filling of the filler is shown in a side view;

[0080] Figure 6 The end of packing deployment is shown in side view;

[0081] Figure 7 A second embodiment is shown;

[0082] Figure 8 A cover of a third embodiment is shown;

[0083] Fig. 9 A fourth embodiment of the cover is shown;

[0084] Fig.10 A longitudinal section of a third embodiment is shown;

[0085] Fig.11A cross section of a third embodiment is shown;

[0086] Fig.12 A longitudinal section of a fourth embodiment is shown;

[0087] Fig.13 A cross section of a fourth embodiment is shown;

[0088] Fig.14 A single plate projection of a second metal layer is shown as a fifth example;

[0089] Fig.15 A sixth embodiment is shown;

[0090] Fig.16 A seventh embodiment is shown;

[0091] It should be noted that these drawings are not drawn to scale. In order to illustrate the present invention, exaggerated representation is useful. DETAILED DESCRIPTION

[0092] Will refer to Figures 1 to 6 The first embodiment of the present invention is described below.

[0093] The first embodiment includes the following method steps:

[0094] a. providing at least one laser bar 3 having a plurality of emitters, which has a first contact surface 9 formed as at least one p-contact on a first side and a second contact surface 11 formed as at least one n-contact on a second side opposite to the first side,

[0095] b. Providing a heat conductor 12 having a first connection surface 13,

[0096] c. providing a cover 15 having a second connection surface 16,

[0097] d. manufacturing at least one filling channel 17 in the cover 15, wherein the filling channel 17 has a filling opening 18, a supply portion 20 and a capillary portion 22 that tapers 21 relative to the supply portion 20, and the capillary portion 22 terminates at the second connection surface 16,

[0098] e. providing a second metal layer 24 having a protrusion structure, which has a plurality of protrusions 33 formed as discrete protrusion points 26 in a cross-sectional plane,

[0099] f. The laser rod 3 is arranged between the heat conductor 12 and the cover 15, wherein the first contact surface 9 faces the first connection surface 13 of the heat conductor, the second contact surface 11 faces the second connection surface 16 of the cover 15, and the second metal layer 24 is at least sectionally arranged between the second connection surface 16 and the second contact surface 11,

[0100] g. generating at least one force 32 having a component pressing the cover 15 in the direction of the heat conductor 12, wherein, under the effect of the force, the first contact surface 9 is pressed flat against the first connection surface 13, wherein the second metal layer 24 undergoes a deformation at least in sections in the region of the raised point 26, and wherein a capillary gap 27 is formed between the second contact surface 11 and the second connection surface 16 between the projection 33, wherein the capillary gap 27 has a smaller hydraulic diameter than the capillary section 22,

[0101] h. Establishing a mechanical connection between the cover 15 and the heat conductor 12,

[0102] i. filling the supply portion 20 with a viscous curable filler 39,

[0103] j. allowing the filler 39 to pass through the capillary portion 22,

[0104] k. Diffusion of the filler 39 into the capillary gap 27 by capillary force,

[0105] 1. Curing the filler 39, in particular by thermal curing and / or chemical curing.

[0106] Figure 1 The working principle of the first embodiment before assembling the diode laser 1 is shown in a front view. A laser bar 3 with a plurality of emitters 6 is shown, which has a first contact surface 9 formed as a p-contact (anode) on a first side 8 and a second contact surface 11 formed as an n-contact (cathode) on a second side 10 opposite to the first side. The laser bar 3 has a thickness variation and a curvature. These features are exaggerated in order to illustrate the working principle of the utility model. A heat conductor 12 with a first connection surface 13 is also shown. The first connection surface is coated with a first metal layer 23 of indium (indicated by square shading). A cover 15 with a second connection surface 16 is also shown. This surface has a slight unevenness, which is exaggerated. A second metal layer 24 of indium (indicated by square shading) is applied to the second connection surface, which has a plurality of raised points 26 and a plurality of depressed points 28. Therefore, the second metal layer can be provided together with the cover. There is no layer material at the depressed points 28. The laser rod 3 is arranged between the heat conductor 12 and the cover 15, the first contact surface 9 faces the first connection surface 13 of the heat conductor, the second contact surface 11 faces the second connection surface 16 of the cover, and the second metal layer 24 is at least sectionally arranged between the second connection surface 16 and the second contact surface 11. In this example, the second metal layer is arranged in such a way that it does not protrude beyond the second contact surface in the y direction. However, as described below Figure 4 As shown, a portion thereof in the -x direction protrudes beyond the contact surface.

[0107] A filling channel 17 is provided in the cover 15, wherein the filling channel 17 has a filling opening 18, a supply portion 20 and a capillary portion 22 which tapers 21 relative to the supply portion 20 and the capillary portion 22 ends at the second connection surface 16. The filling channel 17 is indicated by a dashed line. Figure 4 As shown, it is located at position x inside the cover.

[0108] Figure 2 The diode laser 1 is shown during and after mechanical assembly. At least one force 32 is generated, which has a component that presses the cover 15 in the direction of the heat conductor 12. Under the action of the force, the first contact surface 9 is pressed flat against the first connection surface 13, wherein the second metal layer 24 undergoes plastic deformation at least in sections in the region of the raised points 26. The volume of the layer material remains unchanged, wherein excess material can be pressed into the recessed positions. It can be seen that the above-mentioned unevenness, thickness variations and curvatures are compensated and the emitter 6 is then located in a line. The laser bar 3 can be deformed elastically. The first metal layer 23 is not compressed or hardly compressed because it is designed to have a uniform thickness. It can be seen that the second metal layer 24 produces a connection between the second contact surface and the second connection surface in the normal direction, that is, at the raised points in the z direction. At the recessed points, the second contact surface and the second connection surface are not connected continuously in the normal direction. There, there are interruption points 31 without material closure. A continuous connection in the normal direction exists only at the connection points 30. There are capillary gaps 27 between them.

[0109] Figure 3 The passage of the filler 39 through the capillary section 22 and the expansion of the filler 39 in the capillary gap 27 by capillary forces are shown. Prior to this, the supply section 20 is filled with a viscous curable filler 39. This is introduced from above, in particular in such a way that the supply section 20 is filled without bubbles by the outflow of the filler 39 on the inner wall (right side of the supply section 20) starting from the tapered section 21. The thickness of the capillary gap is exaggerated here. The volume of the supply section should be selected to be much larger than the volume of the capillary gap.

[0110] Figure 4 The side view of the first exemplary embodiment shows the establishment of a mechanical connection of the cover 15 to the heat conducting body 12. The mechanical connection is achieved by an electrically insulating bonding agent 38. The finished diode laser emits laser radiation 2 in the x-direction. The position of the epitaxial layer structure 5 near the first contact surface of the laser bar is also indicated by dashed lines.

[0111] As a precautionary measure, it should be noted that Figures 1 to 9 The shading in the figure is only used to highlight the metal layer and does not represent the cut surface.

[0112] In a modification of the first embodiment (not shown), the first metal layer is not present. The first contact surface is placed directly on the first connection surface.

[0113] Figure 5 The passage of the filler 39 through the capillary section 22 and the expansion of the filler 39 by capillary forces in the capillary gap 27 are shown in a side view. The flow of the filler 39 stops at the front edge 40 shown, and also at the upper edge 41 of the rear facet of the laser bar. These edges serve as tearing edges for the filler 39.

[0114] Figure 6 A fully filled capillary gap is shown.At this stage, the cement has reached the cement tear edges 40, 41 and the spreading of the cement has been completed.

[0115] Figure 7 A front view of the second embodiment is shown before assembly of the diode laser 1. A second metal layer 24 is applied to the second side of the laser bar and is provided together with the laser bar.

[0116] Figure 8 A top view (bottom view) along the viewing direction z on the cover 15 of the third embodiment with a protrusion structure is shown. The raised points 26 of the second metal layer are designed as circular platforms. In the illustration, the raised points are highlighted with square shadows. These platforms can also be called cylindrical protrusions. The protrusion structure exists on the base surface A 25. The sinking points form a continuous surface, which can be imagined as a depression (lowland 37), while the raised points are single discontinuous platform surfaces. In a topological sense, the lowland is a multi-continuous surface.

[0117] Fig. 9 A top view (bottom view) along the viewing direction z on the cover 15 of the fourth embodiment is shown. The raised points 26 of the second metal layer are designed as circular platforms of different sizes. The raised structures are present on the base surface 25 and are distributed unevenly on the surface. As a result, excessive pressure on the laser rod, for example in the edge area, can be avoided.

[0118] Fig.10 A longitudinal section CC of a third embodiment is shown. The raised points 26 are designed as circular platforms 36 on the second connecting surface 16. These are therefore cylindrical protrusions. In this xz section plane (longitudinal section), a plurality of raised points 26 and a plurality of depressed points 28 can be seen.

[0119] Fig.11 A cross section DD of a third embodiment is shown. In this example, a plurality of raised points 26 and a plurality of depressed points 28 can also be seen in the yz sectional plane (cross section) shown.

[0120] Fig.12A longitudinal section CC of a fourth embodiment is shown. In this case, the raised points 26 of the second metal layer are designed as domes 34. The second metal layer is designed here as a raised structure. The positions of the section planes CC and DD can correspond to those of the third embodiment described above.

[0121] Fig.13 A fourth embodiment is shown in cross section.

[0122] Fig.14 A single-plate projection of a second metal layer 24 is shown as a fifth example. In this case, the raised points 26 of the second metal layer are designed as domes 34 arranged in a matrix. This example is intended to illustrate the determination of contour lines. A base surface A 25 with a plurality of raised points can be selected. This can also be the entire base surface of the second metal layer. Each individual dome has an average contour line 29 of a specific length. The sum of all the lengths of the average contour lines gives the total length L. From this, the ratio L / A can be determined.

[0123] In a modification (not shown) of the first to fifth embodiments, the second metal layer is produced by coating the second side of the laser bar. The above embodiments can be combined with each other in various ways within the scope of the invention by a person skilled in the art.

[0124] Fig.15 The diode laser 1 of the sixth embodiment is shown. The cover 15 is indicated by a cutout (hatching). The laser bar 3 with a plurality of emitters is shown. The heat conductor 12 is also shown. A second indium metal layer is applied to the second connection face, which has a plurality of raised points 26 formed as protrusions 33. Thus, the second metal layer can be provided together with the cover. There is no layer material between the protrusions. The laser bar is arranged between the heat conductor 12 and the cover 15.

[0125] A filling channel 17 is provided in the cover 15, wherein the filling channel 17 has a filling opening 18, a filling auxiliary portion 19, a supply portion 20 and a capillary portion 22 which tapers 21 relative to the supply portion 20 and ends at the second connection surface. There are two filling channels here. They are designed perpendicular to the second connection surface.

[0126] Fig.16 A diode laser 1 of a seventh embodiment is shown. The filler channel 17 is formed at an angle between 5° and 45° with respect to the normal to the second connection face. Therefore, the filler can be filled more easily.

[0127] Reference numerals :

[0128] 1. Diode laser

[0129] 2. Laser radiation

[0130] 3. Laser rod

[0131] 4. Substrate 10. Second side

[0132] 5. Epitaxial layer 11. Second contact surface

[0133] 6.Emitter 12.Heat conductor

[0134] 7. Rear facet 13. First connection face

[0135] 8. First side 14. Optical fiber core (core)

[0136] 9. First contact surface 15. Cover

[0137] 16. Second connection surface

[0138] 17. Filling channel

[0139] 18. Fill the opening

[0140] 19. Fill in the auxiliary part

[0141] 20. Supply section

[0142] 21. Tapered section

[0143] 22. Capillary section

[0144] 23. First metal layer

[0145] 24. Second metal layer

[0146] 25. Base surface

[0147] 26. Raised point

[0148] 27. Capillary gap

[0149] 28. Sinking point

[0150] 29. Average Contour

[0151] 30. Connection points in normal direction

[0152] 31. Interruption point in normal direction

[0153] 32. Force

[0154] 33. Protrusion

[0155] 34. Dome

[0156] 35. Back

[0157] 36. Platform

[0158] 37. Depression

[0159] 38.Joint

[0160] 39. Filler

[0161] 40.Torn edge of filler on the front side of the rod

[0162] 41.Torn edge of filler on the back side of the rod

Claims

1. A diode laser (1) comprising at least one edge-emitting laser bar (3), the edge-emitting laser bar comprising a plurality of emitters (6), the emitters having a first contact surface (9) formed as a p-contact and a second contact surface (11) formed as an n-contact, having a normal n and an area A, a heat conductor (12) having a first connection surface (13), a cover (15) having a second connection surface (16) and a second metal layer (24), wherein: The laser rod (3) is arranged between the heat conductor (12) and the cover (15), and the second metal layer (24) is at least sectionally arranged between the second connection surface (16) and the second contact surface (11), The cover (15) is mechanically connected to the heat conductor (12), the first contact surface (9) is thermally and electrically connected to the first connection surface (16) in a flat manner, and the second contact surface (11) is electrically connected to the second connection surface (16) via the second metal layer (24), wherein the second metal layer (24) has a connection point (30) at which the second contact surface (11) is continuously connected to the second connection surface (16) in the direction of the normal line n, and also has an interruption point (31) at which the second contact surface (11) is not connected in the direction of the normal line n. The cover (15) is provided with a cover having a plurality of connecting holes (21) and a plurality of connecting holes (32) connected to the second connecting surface (16), wherein the connecting holes (31) have a total area equal to at least 50% of the area A, and the connecting holes form a gap (27), and the gap (27) is filled with at least 80% of the solidified filler (39), and the cover (15) has at least one filling channel (17), wherein the filling channel (17) has a filling opening (18), a supply portion (20) and a capillary portion (22) which tapers gradually relative to the supply portion (20), and the capillary portion (22) terminates at the second connecting surface (16).

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