Semiconductor laser arrangement and method for producing same

Abstract

The invention relates to a semiconductor laser arrangement comprising a laser-active material which comprises layers of different semiconductor material. A first reflective element and a second reflective element are arranged between the laser-active material, wherein the second element is designed to couple laser light out of the laser-active material. According to the invention, at least one of the first element and second element has a layer stack having an electro-optical layer sequence. The electro-optical layer sequence comprises: a first conductive and in particular transparent layer having a connection point; a second conductive and in particular transparent layer having a connection point; and an in particular insulating layer which is arranged therebetween and for which an optical parameter can be changed depending on a voltage between the first layer and the second layer.

Description

[0001] 2024 PF00204

[0002] 1

[0003] Semi-conductor laser array and method for its manufacture

[0004] The present application takes priority from the German first application DE 10 2024 122 655 . 2 of 08 August 2025, the disclosure content of which

[0005] 5 is hereby fully incorporated by reference. The invention relates to a semiconductor laser arrangement and a method for manufacturing such an arrangement.

[0006] BACKGROUND

[0007] Semiconductor laser arrays, also known as electro-optical components, are required in a wide variety of applications today. These include high-performance applications in projection and lidar, as well as AR and VR applications, and devices in sensor technology and the medical field. The diverse applications necessitate lasers with varying parameters and optimized properties. Depending on the application, these include, for example, the output power of the laser array, a threshold current, modulation capability, collimation, and other factors.

[0008] Especially with conventional semiconductor-based laser arrangements, which are designed as so-called edge-emitting semiconductor lasers, several manufacturing challenges arise. In edge-emitting lasers, the laser emits along an edge through the active zone. This forms a resonator between two mirrored surfaces, with one mirrored surface forming the output coupling side.

[0009] The mirrored surface is created by first breaking the laser burr at two points to define an edge, known as a facet, that is as straight and defect-free as possible along a crystal axis. The facet is then coated with a mirror finish. An additional material is applied to achieve a higher quality. This additional mirror layer serves both to protect the facet and to adjust various optical parameters, such as reflectivity and transmission. One facet is typically fully mirrored, the other partially, so that a resonator with an output- 2024 PF00204

[0010] 2. A pel or emission surface is formed. Furthermore, other electro-optical parameters such as the threshold current or the external quantum efficiency of the laser arrangement during switch-on and switch-off can also be determined by suitable selection of the mirror layer combinations used.

[0011] 5 settings.

[0012] However, the fabrication of such edge-emitting laser arrays is quite complex, as the semiconductor laser structures must first be fractured to create the edges and laser facets that will later be mirrored. Each edge-emitting semiconductor laser array must then be processed individually. Furthermore, the parameters of the mirror layer cannot be subsequently changed on either the back facet or the output-coupling facet, meaning that the electro-optical parameters are essentially fixed after the mirror layer has been applied. Across a larger assembly, where several semiconductor laser structures are individually fabricated and processed, variations can lead to subsequent deviations in the respective semiconductor laser arrays.

[0013] Therefore, there is a need to provide semiconductor laser arrays in which the electro-optical parameters, such as the threshold current mentioned above, the transconductance, or the reflectivity and thus the transmission across the output facet, can be adjusted. Furthermore, a suitable manufacturing process should be developed to enable the efficient and cost-effective production of such semiconductor laser arrays.

[0014] SUMMARY OF THE INVENTION

[0015] This problem is solved by the subject matter of the independent patent claims. Further developments and embodiments of the invention are the subject matter of the dependent claims.

[0016] The inventors propose applying mirror coatings not to broken edges, but to etched surfaces of laser burrs, for example, using non-epitaxial methods. 2024 PF00204

[0017] 3

[0018] Some of these reflective layers possess special electro-optical properties and can be electrically contacted from the outside. By changing these electro-optical properties using an applied voltage, reflection or absorption can be achieved.

[0019] 5 as well as the refractive index or another optical parameter of the mirroring and thus generally one of the facets can be changed.

[0020] This allows an electrical voltage applied to the semiconductor laser array to be used to selectively modify these properties. This enables suitable flexibility of the semiconductor laser array for various applications and / or adaptation of the array to a specific application.

[0021] By implementing a single manufacturing step to create the front and back facets, the proposed principle can be applied directly at the wafer level for a large number of laser burrs simultaneously, thus achieving uniformity in the production of the individual facets and the production of the individual game stories. The mirror layers, with their optical properties that can be modified by applying an electrical voltage, can be applied to the output facet (i.e., the facet with the slightly higher transmission), a back facet, or both facets.

[0022] In this way, laser arrangements can be created whose output power can be adjusted not only via the current through the semiconductor laser arrangement, but also, for example, by quality-controlled optical absorption or reflection. Likewise, the threshold current of such a semiconductor laser arrangement or the slew rate of the start-up of the semiconductor laser arrangement can be specifically adjusted using the proposed methods.

[0023] The inventors therefore propose, in some aspects, a semiconductor laser arrangement comprising a laser-active material with five layers of different semiconductor materials. This laser-active material has an active zone, for example, in the form of a single quantum film or multiple quantum films. The [unclear text] 2024 PF00204

[0024] The proposed semiconductor laser arrangement, formed from four different semiconductor materials, further comprises a first and a second reflecting element, between which the laser-active material is arranged, thus forming, in particular, a resonator. The second reflecting element...

[0025] The fifth reflective element is designed to extract laser light from the laser-active material. The surface of the second reflective element thus forms an extraction plane or a first emission plane of the proposed semiconductor laser arrangement.

[0026] At least one element of the first and second reflecting elements now possesses a layer stack with a controllable electro-optic layer sequence. According to the invention, the electro-optic layer sequence comprises a first conductive, and in particular transparent, layer with a first connection, and a second conductive, and in particular transparent, layer with a second connection. An electro-optic active layer is arranged between the first and second conductive layers. This active layer is configured such that an optical parameter of the optically active layer changes depending on a voltage between the first and second conductive layers. It is particularly advantageous if the optically active layer is, in particular, an insulating layer, so that no current flows through the optically active layer between the first and second conductive layers.

[0027] The electro-optical layer sequence thus forms an integral part of the first and / or second reflecting element. In particular, the reflecting elements are arranged directly on the respective last facet of the laser-active material and are not spaced from it. This allows these layers to be advantageously deposited directly onto the etched ends or facets of a variety of structures made of active materials, which not only makes fabrication more cost-effective but also reduces variations and tolerances.5 The proposed semiconductor laser arrangement can therefore be formed particularly easily as a component on a semiconductor wafer. This makes the fabrication of a large number of such structures particularly favorable.2024 PF00204

[0028] 5. This is advantageous because the production of etched facets can be carried out uniformly and in high quantities on a wafer using a single process, without having to separate the structures as in conventional methods.

[0029] 5. At the same time, the proposed principle nevertheless allows for extensive variability in the product properties of the laser arrangement by adjusting the electro-optical properties using an applied voltage signal. In particular, reflectivity or absorption can be adjusted by adapting the voltage applied to the electro-optical layer sequence. This allows, for example, the fabrication of semiconductor laser arrangements that can be dimmed or have an adjustable output power independent of the laser current.

[0030] Similarly, a lower laser threshold can be achieved, thereby reducing power consumption; or the steepness of the light curve can be changed very quickly. This is particularly interesting for applications in power and high-power operation. By adjusting, for example, the refractive index of one of the reflecting elements using the adjustable electro-optical layer sequence, the stopband can be shifted by adjusting the reflectivity of the mirror. Potential applications for this can be found in augmented reality or virtual reality, as this enables chips with multiple emitters of different wavelengths, thus reducing the number of image errors in an application.

[0031] In some specialized applications, the reflection properties in laser arrangements can thus be switched on the order of a few microseconds or even nanoseconds. This allows the amplitude of laser light from semiconductor laser arrangements to be controlled at high speed according to the proposed principle. This is advantageous, for example, for protection applications, measurement applications, as well as for lidar and others. It is possible to apply not just one, but several electro-optical layers to one or both facets, or to form them as part of the two reflecting elements. These electro-optical layers can be used to generate 2024 PF00204

[0032] Six different effects have been optimized and developed so that different aspects can be realized.

[0033] The semiconductor laser arrangement is based on the proposed principle

[0034] 5 is not limited to a specific laser type. Accordingly, the semiconductor laser arrangement can, in some aspects, include a laser ridge formed with etched facets. In some aspects, the facets are oriented perpendicular to a growth direction of the layers of different semiconductor material. Optionally, the layers of the first and / or the second reflecting element are deposited by, for example, a PVD / CVD, MOCVD, or MBE process. In this aspect, edge-emitting lasers with etched facets are thus used as the basis for the proposed semiconductor laser arrangement. Alternatively, the laser arrangement can also be configured as a VCSEL, i.e., as a vertically emitting laser, where the electro-optical layer sequence is deposited directly as a layer on the laser-active material.

[0035] In these aspects, the semiconductor laser arrangement thus comprises a layer sequence with a laser-active material, wherein the two reflecting elements are planar and essentially perpendicular to the growth direction of the layer sequence with the laser-active material. In this configuration, the facets of the laser-active material are not necessarily etched; rather, the layer sequence with a laser-active material can be grown directly onto a layer sequence of the first reflecting element. In this context, the first reflecting element can be formed with a conductive material, so that it also provides a connection for the laser-active material. In a further aspect, the second reflecting element, forming the output side, is also formed with at least one layer. One of the two reflecting elements comprises the aforementioned electro-optical layer sequence.The at least two conductive layers are provided with a lead wire so that they can be contacted independently of a current through the VCSEL. In some aspects, one of the leads or the conductive transparent layers can also form a contact for the laser-active material. 2024 PF00204.

[0036] 7

[0037] In another aspect, particularly for edge-emitting semiconductor laser arrangements, the etched facet of at least the second element is laterally recessed relative to a fracture edge of the laser arrangement.

[0038] 5 sets. In other words, in some aspects the laser arrangement can include another layer, for example in the form of a substrate, which has a fracture edge that is laterally spaced from the reflecting element that forms the out-coupling side.

[0039] In some other aspects, the fracture edge can be vertically spaced from the facet, with this space being formed by an etched region of semiconductor material layers. Accordingly, in some aspects, a semiconductor laser array is proposed in which the laser-active material is etched to create the facets, on which the reflective elements with at least one electro-optical layer are subsequently deposited. Only after fabrication and completion of such a structure can, in a second step, one or more semiconductor laser arrays be fractured from the wafer according to the proposed principle. In this case, the fracture edge passes through a substrate and no longer directly through the active laser material or its various semiconductor layers.

[0040] The variable optical parameter of the electro-optical layer sequence of the reflecting element can be an absorption, reflection, or transmission adjustable via voltage, or a change thereof. Alternatively, the variable optical parameter can also be a refractive index adjustable via voltage. Various optically active materials can be used for this purpose, which are also insulating in some aspects, so that no current flows through them during operation. Possible materials include LiNbO3, MgNbO3, di-deuterium phosphate, potassium titanyl phosphate, or barium borate. Tungsten oxide and polyaniline, i.e., certain organic compounds, especially for changing the absorption properties, are also conceivable. With organic compounds, care should be taken to ensure that the energy input is not too high to avoid decomposition. In this context, Mate- 2024 PF00204

[0041] Eight materials are referred to as optically active if they change one or more optical properties when exposed to an external electric field. These can be, for example, the refractive index, absorption, transmission, or reflection.

[0042] 5

[0043] Several other aspects of the proposed semiconductor laser arrangement concern the design of the electro-optic layer sequence. In some aspects, the electro-optic layer sequence comprises a multitude of optically active and, in particular, insulating layers arranged between conductive and, in particular, transparent layers, each with its own terminals. These can be two, three, or even more layers, which are in turn separated from one another by conductive and, optionally, transparent layers. The optically active layers can be made of the same material or different materials, or they can be used to realize different functions. For example, conductive metallic oxides such as ITO are used as conductive and transparent layers in some aspects.

[0044] Depending on the design, the electro-optic layer sequence can be arranged in either the second reflecting element, i.e., in the region of the output facet, or in the first reflecting element. This allows for a combination of reflecting elements in the region of the first and second facets, both with and without an electro-optic layer sequence. Specifically, the electro-optic layer sequence can be applied directly to the respective facet or embedded in further layers. Alternatively, it can also be applied to further layers, thus forming the outer layers of the reflecting element (viewed from the facet).

[0045] Depending on the design, the electro-optic layer sequences in the respective reflective elements are configured to generate different optical parameters. In some aspects, the first or second reflective element comprises a DBR mirror with a multitude of layers of different refractive indices. The electro-optic layer sequence can then be arranged behind these layers or in front of such a DBR mirror in some aspects. Alternatively, it is also possible to... 2024 PF00204

[0046] 9 reflective elements with a metallic mirror to achieve the highest possible reflectivity, close to 100%.

[0047] Some aspects concern the electro-optical layer sequence with a

[0048] 5. Material whose refractive index can be varied by means of a voltage. From this perspective, the electro-optic layer sequence comprises at least one layer of a transparent material whose refractive index differs, at least temporarily, from that of a layer sequence forming the DBR mirror. In this way, for example, the properties of a DBR mirror formed by combining layers of a fixed refractive index with the electro-optic layer sequence can be selectively changed by applying a voltage. In some aspects, an electro-optic layer sequence can be combined with a DBR mirror, that is, with another layer sequence of transparent materials with different refractive indices.

[0049] In another aspect, an electro-optical layer sequence is placed in front of or behind a DBR mirror, in which the absorption coefficient, transmittance, or reflection coefficient can be changed by applying a voltage. This allows, for example, the laser threshold to be adjusted and changed.

[0050] The proposed principle allows contact pads for contacting the electro-optical layer sequence to be arranged as close as possible to the laser assembly, depending on the design of the semiconductor laser array. Accordingly, in some aspects, one or more contact pads can be provided, arranged perpendicular to the first and / or second reflecting element on a surface of the layers made of different semiconductor materials. In particular, these contact pads can be arranged next to a laser ridge on the surface of the semiconductor material.

[0051] In another aspect, the contact pads are arranged laterally spaced from the layers of different semiconductor material on a substrate5, which also features the fracture edge of the semiconductor laser array. A combination of these is also possible. Contact can also be achieved via a via, if necessary. The contact pads are electrically 2024 PF00204

[0052] 10. trisch is connected to the first and second conductive layers of the electro-optic layer sequence. In a further aspect, at least one of the layer stacks of the at least one first and second reflecting element also extends partially onto a surface.

[0053] 5 of the layers of different semiconductor material. Accordingly, in this configuration, the layer sequence of the reflective element is applied not only to the etched facet but also to a surface of the semiconductor material perpendicular to it. The layer sequence, or the individual layers or the layers of the electro-optical sequence, can be designed and / or structured differently with respect to their respective thickness or their arrangement on the surface. For example, individual layers, especially the conductive layers, can extend in different directions on the surface to facilitate easier contact, for example, with bond wires.

[0054] Another aspect deals with a method for manufacturing or processing a semiconductor laser array. A substrate is provided, particularly in the form of a wafer. The wafer may contain buffer layers and similar components. In a process step, a laser-active material is structured and produced on the substrate and, if applicable, the buffer. The laser-active material has layers of different semiconductor materials, and the laser-active material includes at least one elongated laser ridge. In this context, the laser ridge possesses an active zone for generating laser light. The active zone is implemented in some aspects as a quantum film or, in others, as a multi-quantum film. A large number of such elongated laser ridges can be produced on the wafer, spaced apart from one another, and particularly parallel to each other.

[0055] In some aspects, it is possible to simply create the necessary layers, including the active zone, at the wafer level and then structure them to form the laser burrs. This can be achieved by applying a photoresist followed by exposure. This creates elongated laser ridges that form the subsequent laser burrs. In this way, burrs of varying lengths and also 2024 PF00204 can be created.

[0056] 11 laser beams arranged at different distances from each other, which contain an active zone for generating laser light.

[0057] 5 In a further step, essentially parallel facets are formed in the elongated laser ridge or the multitude of laser ridges by structured etching of the layers of different semiconductor material. Thus, in contrast to conventional solutions where the facets are generated by fracturing the layers, this process does not involve fracturing the semiconductor layers and the substrate along a crystal axis, but rather an etching step in which the facets of the laser-active material are created so that they are exposed.

[0058] Subsequently, the first and / or second reflective element is deposited onto the facets, particularly using non-epitaxial processes such as PVD / CVD, MOCVD, or MBE. At least one of these two reflective elements comprises a layer sequence with electro-optical properties. This electro-optical layer sequence includes a first conductive layer and a second conductive layer. An optically active layer, which is insulating in some aspects, is positioned between these two conductive layers. An optically active layer is defined here as a material in which at least one optical parameter, such as reflection, absorption, transmission, or refractive index, can be changed by applying an external voltage.

[0059] The two conductive layers are also provided with a connection. Subsequently, the substrate is fractured, sawn, or laser-cut at a lateral distance from the etched facets to create the semiconductor laser array, thus completing the proposed semiconductor laser array. 5 Depending on the embodiment, the step of applying the first and / or second reflective element also includes a structured deposition of the different conductive layers as well as 2024 PF00204

[0060] 12 of the active layer. This is achieved by applying various photoresists, subsequently structuring them, and then depositing the respective layer material. Possible deposition methods include CVD, MOVPE, or other gas-phase deposition.

[0061] Five deposition processes are under consideration. Especially in the case of edge-emitting lasers, these should be able to deposit the necessary material as isotropically as possible.

[0062] In some aspects, the layers of different semiconductor materials are completely etched to create the laser facet, i.e., down to the point where the growth substrate or buffer layer is exposed. An etchant can be used for this purpose that etches selectively depending on the crystal orientation or direction. For example, the laser burrs can also be etched along a preferred crystal direction to produce a smooth and virtually defect-free surface.

[0063] In some aspects, contact pads are deposited on the surface of layers of different semiconductor materials. These contact pads are isolated from the semiconductor material layers and contact the first and second conductive layers. Alternatively, the contacts are applied as pads on a surface of the substrate exposed by the etching process, spaced laterally from the layers of different semiconductor materials.

[0064] BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Further aspects and embodiments according to the proposed principle will be revealed in relation to the various embodiments and examples, which are described in detail in conjunction with the accompanying drawings.

[0066] Figure 1 shows a first embodiment of a semiconductor laser arrangement according to some aspects of the proposed principle;

[0067] Figure 2 shows a second embodiment of a semiconductor laser arrangement according to some aspects of the proposed principle; 2024 PF00204

[0068] 13

[0069] Figure 3 shows a third embodiment of a semiconductor laser arrangement with some aspects according to the proposed principle;

[0070] Figure 4 is a side view of a fourth embodiment of a half-

[0071] 5 conductor laser arrangement with some aspects according to the proposed principle;

[0072] Figure 5 shows a side view of a semiconductor laser arrangement according to some aspects of the proposed principle;

[0073] Figure 6 shows another side view of a semiconductor laser arrangement according to some aspects of the proposed principle;

[0074] Figure 7 shows a third-side view of an embodiment of a semiconductor laser arrangement with some aspects according to the proposed principle;

[0075] Figure 8 is a further side view to illustrate the structure of the reflective elements according to some aspects of the proposed principle;

[0076] Figure 9 shows a top view of a section of a wafer to illustrate some aspects of the proposed principle;

[0077] Figures 10A to IOC are perspective views of a wafer section after corresponding process steps for the production of semiconductor arrangements according to the proposed principle.

[0078] DETAILED DESCRIPTION

[0079] The following embodiments and examples show various aspects and their combinations according to the proposed principle. The embodiments and examples are not always to scale. Likewise, various elements may be enlarged or reduced to highlight individual aspects. It is understood that the individual aspects and features of the embodiments and examples shown in the figures can readily be combined without affecting the invention according to 2024 PF00204.

[0080] - 14 -

[0081] The principle is not affected. Some aspects exhibit a regular structure or form. It should be noted that in practice minor deviations from the ideal form may occur without contradicting the inventive idea.

[0082] 5

[0083] Furthermore, the individual figures, features, and aspects are not necessarily depicted at the correct size, and the proportions between the individual elements may not be entirely accurate. Some aspects and features are emphasized by being shown enlarged. However, terms such as "above," "below," "below," "larger," "smaller," and the like are correctly represented in relation to the elements in the figures. Thus, it is possible to deduce such relationships between the elements from the illustrations.

[0084] Figure 1 shows a first embodiment of a semiconductor laser arrangement based on the proposed principle in the form of an edge-emitting laser. The semiconductor laser arrangement 1 comprises a substrate 14, the respective edges of which are broken off from the wafer after processing to separate them. In this case, the substrate is a growth substrate onto which a sequence of semiconductor layers 12 with a laser-active material 10 is deposited. Specifically, in this embodiment, this material, besides buffer layers, is an n-doped semiconductor material in which a laser ridge has been etched to create the semiconductor laser arrangement. For simplicity, the buffer layers and the doped material are collectively referred to as 12. The laser ridge of the laser-active material 10 comprises an active zone 13 in the form of a multi-layered quantum film and, on top of this, another p-doped layer 11.The laser burr is produced according to known principles at the wafer level.

[0085] According to the principle of the invention, the laser burr and also the doped layer 12 are etched on both sides in order to expose a rear facet (not visible) and an output facet of the laser burr. This step is carried out by completely removing the semiconductor material of layers 11, 12, 13 and 14 in some areas down to the substrate 14, so that the structure- 2024 PF00204

[0086] 15 is laterally recessed with the semiconductor layer 12 compared to the (subsequently generated) fracture edges of the substrate 14. Such a recess can optionally also be made laterally, but is not shown here.

[0087] 5 In the area of ​​the etched facets, two reflective elements 20 and 21 are applied to these and also to the adjacent exposed surface 21' of the layer. The reflective element 20 is deposited in the form of a mirror layer, specifically non-epitactically, onto this rear facet and a part of the rear side surface (not shown) of the semiconductor material 12 and forms the rear highly reflective mirror for the semiconductor laser arrangement. The second reflective element 21 forms the output coupling plane and, in this configuration, comprises an electro-optic layer sequence 218. This lies on the output facet of the laser ridge and the etched surface 21' of the semiconductor material 12, which is arranged perpendicular to it. Leads 212 on the top surface of the semiconductor layer 12 lead to contact pads 210 and 210' arranged thereon. The contact pads 210 and 210' are insulated from the surface of the layer 12. B.by a passivation layer, not shown here, so that when a voltage is applied to the contact pads, a short circuit does not occur in the semiconductor laser arrangement.

[0088] The electro-optic layer sequence 218 also includes an optically active layer located between two conductive layers. The conductive layers, which in this case are transparent and made of, for example, ITO, are connected to the leads. This allows a voltage to be applied to the electro-optic layer sequence.

[0089] With this structure, voltage signals can be applied via the two contact pads 210 and 210', thus selectively modifying an optical parameter of the second reflective element 21. Depending on the configuration, it is possible to apply the electro-optical layer, individual layers thereof, or all layers of the first and / or second reflective element only to the output facet and a portion of the etched surface of the semiconductor layer sequence, and / or to the entire exposed side surface. This simplifies manufacturing and reduces the cost of the 2024 PF00204.

[0090] 16

[0091] Component. Figure 2 shows such a design. In this design, the two contact pads 210 and 210' are also arranged on the same side of the laser burr. Corresponding leads 212 lead to the conductive and transparent layers of the electro-

[0092] 5 optical layer sequence 218 .

[0093] Figure 3 shows another embodiment of the proposed principle, in which the contact pads 210 and 210' are not arranged on the top surface of the semiconductor layer 12, but rather on the exposed surface of the substrate 14. The substrate 14 can be insulating, thus preventing a short circuit. Alternatively, an insulating layer can be applied to the surface beforehand. In this case, such a layer is transparent and simultaneously forms a layer of a DBR mirror of the first and / or second reflecting element. The use of such transparent layers as insulation for the contact pads and the reflecting mirrors, or as a layer to improve output coupling, simplifies fabrication. This simplifies the structuring and subsequent processing of the contact pads 210 and 210'.The leads 212 are now led from the side surface of the semiconductor layer to the surface of the substrate 14.

[0094] The embodiments shown in Figures 1 to 3 depict edge-emitting semiconductor laser arrangements based on the proposed principle. However, the proposed aspect of using electro-optical layers to modify the properties of the laser arrangement is not limited to this design. Rather, vertical designs can also be equipped with the proposed measures.

[0095] Figure 4 shows such an embodiment in the form of a VCSEL or an emitter with a vertical resonator. This is formed on a growth substrate and comprises a back-mounted DBR layer sequence as the first reflecting element 20. The layer sequence also serves as a contact pad and has a conductive layer 5 for supplying the charge carriers to the active zone 13 of the semiconductor laser arrangement. 2024 PF00204

[0096] 17

[0097] Accordingly, the semiconductor laser arrangement as a VCSEL shows the layer sequence 12 and 11 and the active zone 13 arranged between them. The processing of these layers can be carried out in a similar way to edge-emitting lasers, although the composition of the

[0098] 5 layers are adapted to it because of the shorter vertical resonator.

[0099] A further DBR layer sequence is now applied as a reflective element 21 to the layer sequence 11, 12, and 13. Element 21 also comprises an electro-optic layer sequence. One of the two conductive layers of the electro-optic layer sequence also forms the other contact for the vertical laser arrangement. A contact 212 runs along an insulated side of the VCSEL to the electro-optic layer sequence within the second reflective element 21. This contact 212 is connected to a contact 210 on the surface of the substrate 14. In this configuration, the different layer sequences, in particular the reflective elements and the electro-optic layer sequence, can be applied directly to the respective surfaces of the semiconductor layers 12 and 11, respectively.An additional etching step, as in the case of edge-emitting design, is therefore not necessary, but can be carried out to create the best possible defined surface.

[0100] Figures 5, 6 and 7 show some embodiments in a side view according to the proposed principle, with a more detailed representation of the respective reflective elements 20 and 21. The functionalities of these elements shown and described can be combined in any way to achieve a desired application with a variable setting of one or more optical parameters.

[0101] Figure 5 shows a semiconductor laser arrangement in which the laser-active material 10 is applied to a semiconductor layer 12 above a growth substrate 14. The semiconductor layer 125 is subsequently partially etched to expose facets of layers 12, 13, and 11 arranged perpendicular to the substrate 14. The facets of the laser burr preferably run parallel to a defined cris- 2024 PF00204

[0102] 18 vertical axis. The rear facet of the layer sequence 11, 12 and 13 of the laser ridge is subsequently provided with a reflective element 20, which comprises a plurality of transparent layers 205 and 206 with different refractive indices. The layer thickness

[0103] 5 of the respective layers 205 and 206 are tuned to the wavelength of the light generated in the active zone 13 and are, for example, X / 4 in size to create a DBR mirror with a very high reflectivity in this area for the rear element.

[0104] The second reflective element 21 comprises two electro-optic layer sequences separated and spaced apart by a transparent layer 214. Another layer 214 is arranged between the front output facet of the laser-active material and the first electro-optic layer sequence. Each of the two electro-optic layer sequences shown comprises two transparent conductive layers 215 and an insulating, but transparent, second layer 211 arranged between them. This second insulating layer 211 is an optically active layer (i.e., it changes an optical property under an applied electric field) and extends over the entire front face of the laser-active material to a partial region on the top surface.As shown, the individual layer sequences can be designed differently in their length or, more generally, in their geometry on the top side, so that contacting the conductive and transparent layers 215 of the two electro-optical layer sequences is possible. Alternatively, other contacting methods can be selected as shown in the preceding explanations.

[0105] In the present embodiment, the two electro-optic layer sequences 218 are made of the same material, so that they also change the same optical parameters, for example, their refractive index. In this way, a DBR mirror can be produced in which the DBR layers can be varied in their refractive index behavior, thus realizing a refractive index adjustment or change between the individual layers. The electro-optic layer sequences 218 comprise, for example, ITO or another transparent conductive material. This is very thin 2024 PF00204

[0106] 19, so that the thickness of this conductive transparent layer is negligible compared to the thickness of the other layers. In particular, in this embodiment, the electro-optical layer as a whole has a thickness in the range of X / 4 or even

[0107] 5 X / 2 trained.

[0108] Alternatively, the layers of the electro-optic layer sequence 218 can have a suitable thickness in the range of X / 4 and thus form part of the DBR mirror of the second reflecting element. Figure 6 shows such an alternative embodiment, in which the conductive layer 215 also forms part of the layer sequence and is therefore significantly thicker. This variant allows for simpler fabrication because the transparent conductive layers and the respective optically active layers are directly and alternately produced on top of each other in a thickness intended for this purpose, for example, one-quarter of the wavelength in the active region 13.

[0109] Figure 7 shows a further embodiment with a slight modification. In this embodiment, an electro-optic layer sequence 201 is applied directly to the rear facet between the first reflecting element on the back and the facet, and is connected to contact 200 via a conductor (not shown). The optically active layer sequence 201 comprises an optically active layer and corresponding conductive transparent layers in between. In this embodiment, the optically active layer is formed with tungsten oxide, so that, for example, the absorption capacity of the reflecting element on the back can be specifically adjusted. Layer 202, on the other hand, is a metallic mirror and, in addition to having a very high reflectivity of almost 100% for the light from the laser-active material, serves as a second conductive layer for the electro-optic layer sequence.

[0110] This allows, for example, the output power of the semiconductor laser arrangement to be controlled by selectively altering the absorption on the back side. The second reflective element on the front side, with a slightly higher transmission, serves to couple out the laser light. The second reflective element 21 also comprises an electro-optical layer sequence with an optically active layer 211 (in addition to conductive layers not shown here) and a 2024 PF00204

[0111] 20

[0112] A multitude of mirror layers arranged on it form a DBR mirror. The electro-optic layer sequence with the optically active layer 211 can be configured differently compared to the electro-optic layer sequence 201, so that among

[0113] Allows you to adjust 5 different optical parameters.

[0114] Figure 8 shows another embodiment with a slight modification, in which, among other things, the second reflective optical element is initially formed with static and optically unchanging mirror layers 213. An electro-optical layer sequence with the two transparent conductive layers 215 and the optically active layer 211 is then applied to the last of these mirror layers. The rearward first reflective element is again designed as a mirror layer with a multitude of different sublayers 205 and 206 to generate the highest possible reflectivity.

[0115] In all these configurations, the layer sequence covers the facets of the active zone 13 of the laser-active material. It is also evident that the etching process exposes part of the surface of the semiconductor layer sequence 12 or 12', and that the respective initial facets are slightly recessed above the fracture edge of the substrate 14. This allows the laser array to be subsequently fractured and thus isolated along the substrate 14 without the risk of damaging the facets or the reflective elements.

[0116] The proposed principle makes it possible to fabricate a multitude of laser assemblies with laser-active material in a composite on a wafer in one or more process steps. After processing and the application of the reflective elements, the individual semiconductor laser assemblies are separated by making a break along the break edge through the substrate 14 and, if necessary, also through the semiconductor layers 12 and 12'. Figure 9 shows a top view of a section of a wafer with multiple semiconductor laser assemblies before the separation step, with separation occurring both between the individual laser struts and between the assemblies.

[0117] 21 can also occur at the depicted edges, i.e., with multiple bridges on the emitter. The section shows three different semiconductor laser arrangements that are manufactured in parallel. The three laser arrangements are constructed in the same way and comprise a

[0118] 5. Laser-active material 10 with a rear-mounted first reflective element 20 in the form of a metallic mirror and a front-mounted second reflective element 21. The second reflective element 21 serves to couple out laser light, and this element comprises an electro-optic layer. In this representation, the material of the electro-optic layer, or also of the reflective element 21, extends, in addition to the side surface 21', at least partially onto the surface of the semiconductor layer 12 as well as onto the surface of the substrate 14 exposed by the etching process.

[0119] The materials of element 21 and the electro-optic layer sequence are applied to the surfaces. A first contact 210 is applied to the surface of the substrate 14, which leads via a lead to a conductive transparent layer of the electro-optic layer sequence of the second reflective element 21. A second transparent and conductive layer of the electro-optic layer sequence leads along the exposed side surface 21' to the top surface of the semiconductor layer 12 and from there to a contact pad 210' that is also exposed and otherwise insulated from the semiconductor layer 12.

[0120] Figures 10A to IOC show several steps in the fabrication of such a semiconductor laser arrangement. Figure 10 illustrates aspects of how the individual laser ridges are prepared with laser structures. For this purpose, a wafer is provided as a substrate 14, onto which, in addition to a buffer layer, one or more differently doped semiconductor layers are applied over an area. These semiconductor layers are, for example, n-doped. Subsequently, an active zone 13 is formed, followed by a p-doped layer 11. The active zone 13 is, for example, designed as a multi-quantum film. In a further process step, the surface of the p-doped layer 11 is coated with a Fo- 2024 PF00204

[0121] 22 coated with tolac, which is then structured so that in a subsequent etching process material from the reduced layer 11, the active zone 13 and part of the material from the n-doped layer 12 is removed again. This results in the structures shown in Figure 10A.

[0122] Fifth, elongated laser ridges are generated, which form the subsequent laser burrs with the laser-active material 10. The distance between two burrs is chosen as required for subsequent processing. In this way, several burrs per component can be provided on a wafer, or they can be placed at different intervals. The laser burrs themselves extend over a considerable length, as shown here, and are prepared for generating the subsequent lasers.

[0123] In a subsequent step, a second structuring is carried out using photoresist, which is applied to the surface of the structure shown in Figure 10A and then exposed in a structured manner. This is done in such a way that partial areas of the surface of the semiconductor layer 12, as well as the individual laser ridges with the laser-active material 10, are exposed, i.e., after exposure and removal of the photoresist, they become accessible to the etching agent. The exposed surface is then etched. This creates etch facets on the laser ridges of the laser-active material, and a side face of the semiconductor layer 12 is exposed. In this configuration, the etching process is self-terminating and self-adjusting. This is achieved, in part, by the substrate 14, which, depending on the etching agent used, is either not attacked or only minimally affected by it.Likewise, an etching agent can be provided which preferably etches layer 12 and the bar containing the laser-active material 10 along an axis or a crystal plane, so that a surface as smooth as possible is formed as a facet 300 in each laser ridge of the laser-active materials 10. The etching process thus produces the grooves shown in Figure 10B.

[0124] In this way, laser ridges are generated, each bounded by 5 output facets 300. The length of these laser ridges corresponds to a plurality of wavelengths, so that the laser ridges form resonators with the respective output facets 300. In a subsequent 2024 PF00204

[0125] 23

[0126] As shown in Figure I OC, these initial facets are further treated by depositing material on the exposed initial facets and, if necessary, also on the side surface 21'. Depending on the initial facet, i.e., front or back initial facets,

[0127] These layers are formed differently in 5 different facets.

[0128] For example, the respective rear facets (not shown in Figure 10B) are coated with a metallic mirror layer with high reflectivity. Subsequently, a previously applied photoresist is removed. A new photoresist is applied, followed by a structured coating to further process the front facets 300 of the respective laser ridges. This involves the deposition of layers of different materials in several steps, some of which have conductive properties. The embodiment shown in Figure 1OC illustrates an intermediate step of such a procedure, in which an electro-optical layer sequence is applied to the output facet 300, and a conductive layer of this sequence extends onto a portion of the side surface 21' of the output facet as well as onto the surface of the semiconductor layer sequence 12.

[0129] This material is isolated from the surface of the semiconductor layer sequence 12 and can therefore form a corresponding contact. In further steps, additional transparent layers can now be applied until the desired reflective element 21 is completed. Subsequently, the individual laser devices are broken along the etched exposed areas of the substrate 14. In a further final step, lateral etching, i.e., parallel to the laser burrs, can also be performed to remove material between the individual laser burrs of the semiconductor layer 12. Singulation is achieved by breaking along defined fracture edges in the substrate 14, which are sufficiently laterally removed from the reflective elements and the laser burrs to prevent damage.

[0130] The proposed principle creates semiconductor arrangements in which the optical properties remain unchanged even after manufacturing. 2024 PF00204

[0131] - 24 - can be selectively modified and adjusted by applying a voltage signal. The semiconductor laser arrangements, and in particular the reflective elements, are manufactured in a common process using well-known and understood methods. This allows for the uniform processing of a large number of such semiconductor laser arrangements on a common wafer, and thus the production of arrangements with low tolerance.

[0132] 2024 PF00204

[0133] REFERENCE MARK LIST

[0134] I Semiconductor laser arrangement

[0135] 10 laser-active material

[0136] II layers

[0137] 12, 12 layers

[0138] 13 active zones, multi-film

[0139] 14 Substrat

[0140] 20 reflective elements

[0141] 21 reflective element

[0142] 21 ' exposed area

[0143] 200 contact pads

[0144] 201 optically active layer

[0145] 202 mirrors

[0146] 205, 206 layers with different refractive indices

[0147] 210 . 210 ' Contact pad

[0148] 211 optically active layer

[0149] 212 Supply line

[0150] 213 mirror layers, DBR layers

[0151] 214 transparent layer

[0152] 215 electrically conductive layer

[0153] 218 electro-optical layer sequence

[0154] 300 etched facet

Claims

2024 PF00204 26 PATENT CLAIMS 1. Semiconductor laser arrangement, comprising: A laser-active material which forms layers of different thicknesses 5 semiconductor materials included , A first and a second reflective element, between which the laser-active material is arranged, wherein the second reflective element is configured for coupling laser light out of the laser-active material; wherein at least one of the first and second reflective elements has a stack of layers with an electro-optic sequence of layers, and the electro-optic sequence of layers comprises: o a first conductive and in particular transparent layer with a terminal; o a second conductive and in particular transparent layer with a terminal; o an optically active and in particular insulating layer arranged between them, in which an optical parameter is variable depending on a voltage between the first and the second layer.

2. Semiconductor laser arrangement according to claim 1, wherein the laser-active material is formed as a laser ridge with etched facets, which are in particular perpendicular to a growth direction of the layers of different semiconductor material, and wherein optionally the first and second reflecting element are applied in particular non-epitactically, in particular by sputtering, or by PVD or CVD processes.

3. Semiconductor laser arrangement according to claim 2, wherein the etched facet of at least the second element is laterally recessed relative to a fracture edge, wherein optionally the fracture edge is vertically spaced from the facet by an etched area of ​​layers of the semiconductor material. 2024 PF00204 27 4. Semiconductor laser arrangement according to claim 1, wherein the first and second reflecting elements are substantially parallel to a growth direction of the layers of different semiconductor material. 5 5. Semiconductor laser arrangement according to one of the preceding claims, wherein the variable optical parameter comprises: an absorption adjustable via the voltage; and / or a refractive index adjustable via the voltage.

6. Semiconductor laser arrangement according to one of the preceding claims, wherein the optically active and in particular insulating layer comprises at least one of the following materials: - LiNbO x ; MgNbO x ; Di-deuterium phosphate; Potassium titanyl phosphate; Barium borate; Tungsten oxide, W0 x ; and polyaniline .

7. Semiconductor laser arrangement according to one of the preceding claims, wherein the electro-optic layer sequence comprises a plurality of optically active and insulating layers arranged between conductive and, in particular, transparent layers with respective terminals.

8. Semiconductor laser arrangement according to one of the preceding claims, wherein - the second reflecting element, the layer stack with an electro-optical layer sequence; and / or - the first reflecting element comprises the layer stack with an electro-optic layer sequence. 5 9. Semiconductor laser arrangement according to one of the preceding claims, wherein the first and / or the second reflecting element comprises at least one of the following: 2024 PF00204 28 a DBR mirror with a multitude of layers of different refractive indices; a metallic mirror . 5 10. Semiconductor laser arrangement according to one of the preceding claims, in which the layer stack with an electro-optic layer sequence comprises at least one layer of a transparent material whose refractive index is at least temporarily different from the optically active and, in particular, insulating layer; and / or the layer stack with an electro-optic layer sequence comprises at least one further layer sequence of transparent materials of different refractive indices.

11. Semiconductor laser arrangement according to one of the preceding claims, wherein the second reflecting element has a higher transmittance than the first reflecting element.

12. Semiconductor laser arrangement according to one of the preceding claims, further comprising: one or more contact pads arranged perpendicular to the first and / or second reflective element on a surface of layers of different semiconductor material or of a laterally spaced substrate and electrically connected to the first and second conductive layer.

13. Semiconductor laser arrangement according to one of the preceding claims, wherein at least one of the layer stacks of the at least one first and second reflecting element extends at least partially onto a surface of the layers of different semiconductor material.

14. Semiconductor laser arrangement according to one of the preceding claims ,5 wherein a thickness of the layers of the electro-optic layer sequence is different . 2024 PF00204 29 15. Method for processing a semiconductor laser arrangement, comprising the steps: Providing a substrate; Comprehensive creation of a structured laser-active material 5 layers of different semiconductor material, wherein the laser-active material comprises at least one elongated laser ridge; Generating two essentially parallel facets in the elongated laser ridge by structured etching of layers of different semiconductor material; Applying a first and a second reflective element to the etched facets, wherein at least one of the first and second elements comprises a layer stack with an electro-optic layer sequence, and the electro-optic layer sequence comprises: a. a first conductive and, in particular, transparent layer with a terminal; b. a second conductive and, in particular, transparent layer with a terminal; c. an optically active and, in particular, insulating layer arranged between, wherein an optical parameter is variable depending on a voltage between the first and the second layer; Fracture of the substrate at a lateral distance from the etched facet to create the semiconductor laser array.

16. Method according to claim 15, wherein the step of applying a first and a second reflective element comprises: structured deposition of the first conductive and in particular transparent layer on at least one of the facets; structured deposition of the optically active and in particular insulating layer on the first conductive layer; structured deposition of the second conductive and in particular transparent layer on the optically active and in particular insulating layer.

17. Method according to one of claims 15 and 16, further comprising: 2024 PF00204 - 30 - Applying at least two contact surfaces to a surface of layers of different semiconductor material and / or an exposed surface of the substrate laterally spaced from the layers of different semiconductor material.

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