Semiconductor laser and method for manufacturing such a semiconductor laser

Abstract

Semiconductor laser (1) with - at least one surface-emitting semiconductor laser chip (4) comprising a semiconductor layer sequence (40) with at least one active zone (41) for generating laser radiation (L) and comprising a light-emitting surface (44) oriented perpendicular to a growth direction (G) of the semiconductor layer sequence (4) and at which the semiconductor laser chip (4) emits the laser radiation (L), and - a diffractive optical element (3) configured to expand and disperse the laser radiation (L), wherein - an optically effective structure (33) of the diffractive optical element (3) made of a material with a refractive index of at least 1.65, based on a wavelength of maximum intensity of the laser radiation (L), - the optically effective structure (33) is located on a side of the diffractive optical element (3) facing the semiconductor laser chip (4), and - a connecting means (5) for the diffractive optical element (3) is located at an edge of the diffractive optical element (3), such that the light exit surface (44) is at least partially free of the connecting means (5) and such that a gap (6) is formed at least partially between the diffractive optical element (3) and the light exit surface (44); wherein (i) the connecting element (5) is applied directly to the light-emitting surface (44) in a frame-like manner and is in direct contact with the diffractive optical element (3); or (ii) the semiconductor laser chip (4) has a growth substrate (2) on which the semiconductor layer sequence (40) is epitaxially grown, wherein the connecting means (5) and the semiconductor layer sequence (40) are arranged laterally spaced apart from each other on the growth substrate (2) and wherein the connecting means (5) is in direct contact with the growth substrate (2) and the diffractive optical element (3).

Description

[0001] A semiconductor laser is described. Furthermore, a method for manufacturing such a semiconductor laser is described.

[0002] Document US 2016 / 0 156 154 A1 concerns a surface-emitting semiconductor element.

[0003] Document US 2016 / 0 164 261 A1 describes a compact multi-zone infrared laser.

[0004] The publication DE 100 58 949 A1 aims at a high-speed infrared transmitting / receiving device with high efficiency and low cost.

[0005] The publication US 2008 / 0 232 418 A1 describes a surface-emitting laser.

[0006] The publication DE 10 2004 063 569 A1 concerns a surface-emitting laser with an integrated lens.

[0007] Document US 2005 / 0 063 071 A1 specifies methods for the production of diffractive optical elements.

[0008] Document US 2003 / 0 081 638 A1 concerns a semiconductor laser array with multiple wavelengths.

[0009] The publication DE 10 2016 100 220 A1 describes an optical device for illuminating a sensor device for a vehicle.

[0010] The publication JP 2004 096 091 A describes a housing for a surface-emitting laser.

[0011] One task to be solved is to specify a semiconductor laser that is eye-safe and can be manufactured efficiently.

[0012] This problem is solved by a semiconductor laser and by a method with the features of the independent claims. Preferred embodiments are the subject of the dependent claims.

[0013] The semiconductor laser comprises one or more semiconductor laser chips. Each semiconductor laser chip consists of a sequence of semiconductor layers. This sequence includes one or more active zones for generating laser radiation. The semiconductor laser chip also has a light-emitting surface. The laser radiation is emitted from this surface.

[0014] According to at least one embodiment, the at least one semiconductor laser chip is a surface emitter. This means, in particular, that the semiconductor laser chip emits the laser radiation generated during operation from a comparatively large surface. The surface, i.e., the light-emitting surface from which the semiconductor laser chip emits the laser radiation, is preferably oriented perpendicular or approximately perpendicular to a growth direction of the semiconductor layer sequence, such that a resonator direction runs parallel or approximately parallel to the growth direction. "Approximately" here and in the following refers in particular to a tolerance of at most 15°, 5°, or 2°. In contrast to surface emitters, edge emitters, on the other hand, have an emission direction and a resonator direction perpendicular to the growth direction.

[0015] The semiconductor layer sequence is preferably based on a 13-15 compound semiconductor material. This semiconductor material is, for example, a nitride compound semiconductor such as Al. n In 1-n-m Ga m N or a phosphide compound semiconductor material such as Al n In 1-n-m Ga m P or also an arsenide compound semiconductor material such as Al n In 1-n-m Ga m As or like Al n Ga m In 1-n-m As k P 1-k, where 0 ≤ n ≤ 1, 0 ≤ m ≤ 1, and n + m ≤ 1, as well as 0 ≤ k < 1. Preferably, for at least one layer or for all layers of the semiconductor layer sequence, 0 < n ≤ 0.8, 0.4 ≤ m < 1, and n + m ≤ 0.95, as well as 0 < k ≤ 0.5, apply. The semiconductor layer sequence may contain dopants and additional components. For the sake of simplicity, however, only the essential components of the crystal lattice of the semiconductor layer sequence, i.e., Al, As, Ga, In, N, or P, are specified, even though these may be partially replaced and / or supplemented by small amounts of other substances.

[0016] The semiconductor laser comprises at least one diffractive optical element (DoE). This diffractive optical element(s) is designed to spread and disperse the laser radiation, particularly over a larger solid angle. The diffractive optical element ensures that the semiconductor laser, due to the resulting divergence of the laser radiation, is not particularly dangerous to the human eye. Therefore, the semiconductor laser is eye-safe without further measures and complies with the relevant legal requirements.

[0017] As an alternative to a diffractive optical element, a beam-expanding optical element can also be used. The beam-expanding optical element is, for example, a microlens array (MLA). The microlens array comprises a plurality of individual lenses, preferably arranged close together. The generated laser radiation passes through a region of the light-exiting surface, which is preferably covered by at least 10, 30, or 100 of the microlenses. Alternatively or additionally, the beam-expanding optical element can include or consist of a scattering layer, also called a diffuser. A scattering layer comprises, in particular, a roughened surface at which the laser radiation is scattered, and / or scattering particles in a matrix material transparent to the laser radiation. The following descriptions for the diffractive optical element apply equally to the beam-expanding optical element.

[0018] An optically active structure of the diffractive optical element is formed from a material with a high refractive index. The refractive index of this material is at least 1.65, and particularly at least 1.75, 1.8, 2.0, or 2.2. These refractive index values ​​preferably apply at the operating temperature of the semiconductor laser and at the wavelength of maximum intensity of the laser radiation generated during operation. Furthermore, the refractive index is preferably higher than that of epoxides. High-refractive-index epoxides achieve values ​​of approximately up to 1.6.

[0019] The optically effective structure is, in particular, a grating-like structure that acts similarly to a diffraction grating and / or a hologram for the laser radiation. The laser radiation is expanded and dispersed by the optically effective structure, with the expansion and dispersal preferably being primarily or exclusively due to light diffraction.

[0020] The optically active structure is, for example, made of a 13-15 compound semiconductor material. Likewise, 12-16 semiconductors such as ZnO, ZnS, ZnTe, Ga₂O₃, or In₂O₃ can be used. Furthermore, instead of single-crystal semiconductor layers fabricated via metal-organic vapor deposition, other semiconductor layers can also be employed. In particular, amorphous layers of metal oxides with a high refractive index, such as ZnO, SnO₂, or Ta₂O₅, are suitable for the optically active structure.

[0021] Other examples of materials for the optically active structure are Al₂O₃, especially as sapphire crystal, GaAs, or GaN, particularly when the optically active structure is etched into the growth substrate of the laser or the semiconductor layer sequence. If the optically active structure is to be produced from a layer deposited onto the laser disk, layers of dielectrics such as aluminum oxide or silicon nitride, each not necessarily with a precise stoichiometric composition and / or usually amorphous, can also be practical.

[0022] The semiconductor laser comprises at least one surface-emitting semiconductor laser chip having a semiconductor layer sequence with at least one active zone for generating laser radiation and a light-emitting surface oriented perpendicular to a growth direction of the semiconductor layer sequence. Furthermore, the semiconductor laser includes a diffractive optical element configured to spread and disperse the laser radiation, thus preferably making the semiconductor laser eye-safe. An optically effective structure of the diffractive optical element is made of a material with a refractive index of at least 1.65 or 2.0, based on a wavelength of maximum laser radiation intensity.

[0023] In an alternative embodiment, the semiconductor laser comprises at least one surface-emitting semiconductor laser chip having a semiconductor layer sequence with at least one active zone for generating laser radiation and a light-emitting surface oriented perpendicular to a growth direction of the semiconductor layer sequence. Furthermore, the semiconductor laser includes a beam-expanding optical element configured to expand and disperse the laser radiation, thus making the semiconductor laser eye-safe. An optically active structure of the beam-expanding optical element can be made of a material with a high refractive index. Preferably, the semiconductor layer sequence includes at least one Bragg mirror traversed by at least one electrical via. An electrical contact can be arranged around the light-emitting surface.This contact is preferably located between the beam-expanding optical element and the associated Bragg mirror, through which the via passes to connect this contact.

[0024] For many applications, it is essential that a light source be eye-safe for the human eye. With semiconductor lasers, additional measures must be taken to achieve this; in particular, the laser radiation can be spread and dispersed using diffractive optical elements. If such a diffractive optical element is made of a material with a relatively low refractive index, the level of eye protection may be limited depending on the environmental conditions.

[0025] For example, in the case of dew formation, condensation, or moisture deposits on the diffractive optical element, the beam-widening effect of the diffractive optical element can be lost due to the reduced refractive index difference between the environment and the optically effective structure. This problem is solved in the semiconductor laser described here, as even in the case of dew formation on the diffractive optical element, a sufficiently large refractive index difference exists to ensure eye safety through beam shaping by the diffractive optical element.

[0026] Furthermore, it is possible to attach the diffractive optical element described here to the semiconductor laser chip using an adhesive. Organic plastics or inorganic materials with a comparatively low refractive index, such as SiO2, can be used as adhesives. Such materials can penetrate the optically active structure and even fill the approximately lattice-like structure, since the diffractive optical element continues to function due to the still-present, significant difference in refractive index.

[0027] Furthermore, by using appropriate materials, it is possible to deposit the diffractive optical element either at the wafer level onto the as-yet-unseparated semiconductor laser chips via a suitable joining process, or to assign it to already isolated semiconductor laser chips, either collectively or in groups. The optically effective structure with its high refractive index enables such processes to be carried out efficiently.

[0028] According to at least one embodiment, the semiconductor laser is surface-mountable. This means that the semiconductor laser is preferably suitable for surface mounting (SMT) using lead-free soldering or adhesive bonding processes. In particular, the semiconductor laser can be mechanically and / or electrically mounted on a substrate such as a circuit board without penetrating any material.

[0029] According to at least one first alternative, the diffractive optical element is located at the light-emitting surface. Preferably, only a connecting element is located between the diffractive optical element and the light-emitting surface, via which the diffractive optical element is connected to the semiconductor laser chip.

[0030] The optically active structure of the diffractive optical element is located on a side of the diffractive optical element facing the semiconductor laser.

[0031] The bonding material between the semiconductor laser chip and the diffractive optical element is located only at one edge of the diffractive optical element. Specifically, the light-emitting surface is free or predominantly free of the bonding material. A gap is formed between the light-emitting surface and the diffractive optical element, either partially or across the entire surface. In this context, "gap" means that no solid or liquid is present. The gap may be filled with one or more gases or evacuated. In this case, the bonding material may also be opaque to the generated laser radiation and could, for example, be a metal or a metal alloy.

[0032] According to the first alternative, the diffractive optical element is located directly at the light-emitting surface. The optically active structure is located on one side of the diffractive optical element facing the light-emitting surface.

[0033] According to at least one embodiment, the diffractive optical element comprises a support substrate. The support substrate is, for example, a semiconductor substrate such as gallium nitride or gallium arsenide, or a transparent material such as sapphire or silicon carbide. Preferably, the support substrate is transparent to the laser radiation generated during operation.

[0034] According to at least one embodiment, the optically effective structure is formed in the support substrate. For example, the support substrate can be structured accordingly, such as photolithographically.

[0035] According to at least one embodiment, the optically effective structure is formed from a layer of raw material applied to the substrate. In other words, in this case it is not the substrate itself, but the layer of raw material that is structured, for example photolithographically or via a nanoimprinting process.

[0036] According to at least one embodiment, the optically active structure only partially penetrates the diffractive optical element. In particular, the support substrate and / or the raw material layer remain as a continuous, uninterrupted layer. In other words, the optically active structure then only partially penetrates the support substrate and / or the raw material layer. Alternatively, it is possible that the diffractive optical element is completely penetrated by the optically active structure, so that the optically active structure forms through holes or openings in the diffractive optical element.

[0037] According to at least one embodiment, the optically active structure comprises or consists of one or more semiconductor materials. It is possible that the optically active structure is made of the same or different semiconductor materials as the semiconductor layer sequence of the semiconductor laser chip. If the optically active structure comprises or consists of at least one semiconductor material, the support substrate of the diffractive optical element preferably represents a growth substrate for this semiconductor material of the optically active structure.

[0038] According to at least one second alternative, the semiconductor laser chip includes a growth substrate for the semiconductor layer sequence. The semiconductor layer sequence is epitaxially grown on the growth substrate, and the growth substrate is preferably still present in the finished semiconductor laser.

[0039] According to at least one embodiment not claimed herein, the diffractive optical element is formed in the growth substrate of the semiconductor laser chip. The diffractive optical element, and in particular its optically active structure, is preferably located on the side of the growth substrate facing away from the semiconductor layer sequence with the active zone.

[0040] According to at least one embodiment not claimed herein, the diffractive optical element forms the light-emitting surface of the semiconductor laser chip. In other words, the generated laser radiation leaves the semiconductor laser chip at the diffractive optical element, in particular at the optically active structure.

[0041] According to at least one embodiment not claimed herein, the diffractive optical element and the semiconductor laser chip are formed in one piece. This means, for example, that there is no joining zone or bonding layer between the semiconductor laser chip and the diffractive optical element. In particular, the semiconductor laser chip and the diffractive optical element have a common component, which is specifically formed by the growth substrate of the semiconductor layer sequence.

[0042] According to at least one embodiment not claimed herein, the semiconductor laser chip and a connecting means for the diffractive optical element are mounted on a common mounting carrier. Viewed from above, the connecting means is preferably located exclusively next to the semiconductor layer sequence and / or next to the semiconductor laser chip and / or next to the active zone. In particular, the connecting means and the semiconductor laser chip do not touch.

[0043] According to at least one embodiment not claimed herein, the connecting element is in direct contact with the mounting bracket and / or the diffractive optical element. The connecting element can engage with the optically active structure of the diffractive optical element and partially fill this structure.

[0044] According to at least one embodiment, the diffractive optical element completely covers the light-emitting surface and / or the semiconductor layer sequence and / or the semiconductor laser chip. This applies particularly when viewed from above.

[0045] According to at least one embodiment, the semiconductor laser comprises several semiconductor laser chips. The semiconductor laser chips can be identical in construction and emit radiation of the same wavelength, or they can be designed differently.

[0046] According to at least one embodiment, the semiconductor laser chip, or at least one of the semiconductor laser chips, has multiple laser regions. In this case, the semiconductor laser preferably comprises exactly one semiconductor laser chip. Particularly in the case of VCSEL (Vertical-Cavity Surface Emitting Laser) lasers, the semiconductor laser chip includes multiple laser regions, also referred to as individual lasers, which are preferably aligned parallel to one another and / or have resonator axes parallel to the growth direction of the semiconductor layer sequence. The individual lasers can form individual VCSELs, so that the semiconductor laser chip in question represents a VCSEL array. Sufficient or particularly high optical output power can be achieved via such a VCSEL array. The individual lasers are preferably arranged in a matrix within the semiconductor laser chip and can preferably be operated in parallel.The individual lasers can be electrically connected in parallel and / or can only be operated together. Likewise, the individual lasers can be controlled independently of each other, either individually or in groups.

[0047] It is possible for a diffractive optical element to span several semiconductor laser chips and / or several individual lasers together and combine them into a single component.

[0048] According to at least one embodiment, the semiconductor laser chips of the semiconductor laser are jointly and preferably completely covered by the diffractive optical element. In particular, all light-emitting surfaces of the semiconductor laser chips can each be completely covered by the diffractive optical element. The diffractive optical element preferably extends continuously, in one piece, and / or without gaps across all semiconductor laser chips.

[0049] According to at least one embodiment, the diffractive optical element is located close to the semiconductor laser chip and / or the light-emitting surface. Preferably, the distance between the diffractive optical element and the semiconductor laser chip is at most 20, 10, or 5 times, and / or at least 1, 2, or 4 times, the wavelength of maximum laser intensity. Alternatively or additionally, the distance between the semiconductor laser chip and the diffractive optical element is at most 0.5 mm, 0.2 mm, 0.05 mm, or 20 µm. That is, there is no or no significant spatial separation between the diffractive optical element and the semiconductor laser chip.

[0050] According to at least one embodiment, the diffractive optical element and / or the at least one semiconductor laser chip is partially or completely enclosed by a potting material. The potting material is preferably made of a plastic with a comparatively low refractive index, such as a silicone, an epoxy, an acrylate, or a polycarbonate. The potting material is preferably transparent to the generated laser radiation.

[0051] According to at least one embodiment not claimed herein, the potting material contacts the optically effective structure. The potting material can contact the optically effective structure only at an edge or over the entire light-emitting surface.

[0052] According to at least one embodiment, the semiconductor layer sequence comprises one or more Bragg mirrors. The at least one Bragg mirror is configured to reflect the laser radiation.

[0053] According to at least one embodiment, the Bragg mirror is penetrated by at least one electrical via. The via is preferably metallic. In particular, the via is electrically insulated from the Bragg mirror through which it passes.

[0054] According to at least one embodiment, electrical connection surfaces for external electrical contacting of the semiconductor laser are located on a common side of the active zone. This allows the semiconductor laser to be surface-mounted.

[0055] According to at least one embodiment, at least one current constriction is generated in the at least one Bragg mirror or several Bragg mirrors. This ensures that the active zone is energized during operation only in one or more current-passing regions of the current constriction. The current constriction is preferably located within the associated Bragg mirror and not at an edge of the Bragg mirror, as viewed along the growth direction of the semiconductor layer sequence.

[0056] According to at least one embodiment, the semiconductor laser comprises two Bragg mirrors. These are located on opposite sides of the active zone. It is possible that each of the Bragg mirrors is penetrated by one or more of the vias.

[0057] According to at least one embodiment, the semiconductor laser comprises an anode contact and / or a cathode contact. The contacts are preferably metallic. Current is preferably injected directly into the semiconductor layer sequence via the contacts.

[0058] According to at least one embodiment, the anode contact and / or the cathode contact extends between the semiconductor layer sequence and the diffractive optical element. This allows the light-emitting surface, viewed from above, to be completely surrounded by the material of the anode contact and / or the cathode contact on a side facing the diffractive optical element. In this case, the anode contact and / or the cathode contact are opaque to the generated laser radiation and / or metallic.

[0059] Furthermore, a method for manufacturing a semiconductor laser is disclosed. The method is preferably used to manufacture a semiconductor laser as described in connection with one or more of the embodiments mentioned above. Features of the method are therefore also disclosed for the semiconductor laser, and vice versa.

[0060] In at least one embodiment, the method comprises the following steps, preferably in the specified order: - Providing the semiconductor laser chip, and - Attaching the diffractive optical element to the semiconductor laser chip.

[0061] The method and semiconductor laser described here eliminate the need for costly and / or material-intensive active adjustment at the component level. Furthermore, the use of semiconductor processes, particularly passive adjustment at the wafer level, can reduce manufacturing costs. For example, it is possible to tailor the production of a semiconductor laser component to customer-specific emission characteristics directly at the wafer level, such as to enable more collimated emission for easier further processing by the customer.

[0062] Furthermore, layers or materials with a high refractive index can usually be efficiently structured using processes available in semiconductor manufacturing. In particular, diffractive optical elements can be combined with semiconductor laser chips directly at the wafer level. This allows for the cost-effective and precise alignment of diffractive optical elements and semiconductor laser chips, if required. This significantly reduces assembly effort. Additionally, semiconductor lasers can be tested at the wafer level, and the effect of the diffractive optical elements can be analyzed and verified there as well.

[0063] In the diffractive optical element described here, which is intimately bonded to the semiconductor laser chip, there is no need for subsequent covering of the semiconductor laser chip with a separate diffractive optical element. Furthermore, the diffractive optical element can serve as a protective layer for the semiconductor laser chip in this described semiconductor laser. If the diffractive optical element is, for example, bonded to the semiconductor laser chip, the substrate of the diffractive optical element can already provide sufficient mechanical protection for the semiconductor laser. Due to the high refractive index of the optically active structure, it is also possible for the optically active structure to be located on a side of the diffractive optical element facing away from the semiconductor laser chip, and for the diffractive optical element to be coated with an encapsulating plastic to achieve additional protection.

[0064] The semiconductor laser and the method described here can be characterized in particular by at least one of the following aspects, which are numbered and referenced for the sake of simplicity. 1. Semiconductor lasers with - at least one surface-emitting semiconductor laser chip comprising a semiconductor layer sequence with at least one active zone for generating laser radiation and comprising a light-emitting surface oriented perpendicular to a growth direction of the semiconductor layer sequence, and - a diffractive optical element designed to spread and disperse the laser radiation, where - an optically effective structure of the diffractive optical element made of a material with a refractive index of at least 1.65, based on a wavelength of maximum intensity of the laser radiation, and - the semiconductor laser is eye-safe due to the diffractive optical element widening and spreading of the laser radiation. 2. Semiconductor lasers according to the previous aspect, in which the diffractive optical element is located at the light exit surface, so that at least in some places there is only a connecting means for the diffractive optical element between the diffractive optical element and the semiconductor laser chip. 3. Semiconductor lasers according to the previous aspect, in which the bonding agent is located across the entire surface between the light-emitting surface and the diffractive optical element, so that the bonding agent completely covers the light-emitting surface. 4. Semiconductor lasers according to aspect 2, in which the connecting element is located at an edge of the diffractive optical element, such that the light-emitting surface is free of the connecting element and such that a gap is formed at least partially between the diffractive optical element and the light-emitting surface. 5. Semiconductor lasers according to one of aspects 2 to 4, in which the connecting agent engages at least partially in the optically effective structure and completely fills the optically effective structure at least partially. 6. Semiconductor lasers according to aspect 1, where the diffractive optical element is located directly and across the entire surface of the light exit surface. 7. Semiconductor lasers according to one of the preceding aspects, in which the diffractive optical element comprises a support substrate, wherein the optically effective structure is located on one side of the support substrate facing the light emission surface. 8. Semiconductor lasers according to the previous aspect, in which the optically effective structure is made of a semiconductor material, wherein the support substrate is a growth substrate for the semiconductor material of the optically effective structure. 9. Semiconductor lasers according to aspect 1, in which the semiconductor laser chip comprises a growth substrate of the semiconductor layer sequence and the diffractive optical element is formed in a side of the growth substrate facing away from the semiconductor layer sequence, wherein the diffractive optical element forms the light exit surface, such that the diffractive optical element and the semiconductor laser chip are formed in one piece. 10. Semiconductor lasers according to aspect 1, in which the semiconductor laser chip and a connecting means for the diffractive optical element are mounted on a common mounting carrier, such that the connecting means is only located next to the semiconductor laser chip when viewed from above and does not touch the semiconductor laser chip, wherein the connecting element is in direct contact with the mounting carrier and the diffractive optical element and the diffractive optical element completely covers the semiconductor laser chip. 11. Semiconductor laser according to one of the preceding aspects, comprising several of the semiconductor laser chips, wherein the semiconductor laser chips are jointly and completely covered by the diffractive optical element, which is contiguous and formed in one piece. 12. Semiconductor laser according to one of the preceding aspects, wherein the distance between the diffractive optical element and the semiconductor laser chip is at most ten times the wavelength of maximum intensity of the laser radiation. 13. Semiconductor lasers according to one of the preceding aspects, in which the diffractive optical element is at least partially directly enclosed by a potting material, where the potting material touches the optically effective structure. 14. Semiconductor lasers according to one of the preceding aspects, wherein the optically effective structure of the diffractive optical element is made of a material with a refractive index of at least 2.0. 15. Semiconductor laser according to one of the preceding aspects, wherein the semiconductor layer sequence includes at least one Bragg mirror, wherein the Bragg mirror is penetrated by an electrical via and electrical connection pads are located on a common side of the active zone, so that the semiconductor laser is surface-mountable, and wherein a current constriction is created in the Bragg mirror, so that the active zone is only energized in at least one current-passing region of the current constriction during operation. 16. Semiconductor lasers according to the previous aspect, which includes two of the Bragg mirrors, located on opposite sides of the active zone, where each of the Bragg mirrors is penetrated by the via. 17. Semiconductor laser according to one of the preceding aspects, wherein an anode contact or a cathode contact extends between the semiconductor layer sequence and the diffractive optical element, such that the light-emitting surface is surrounded on a side facing the diffractive optical element, viewed from above, by a material of the anode contact or the cathode contact, wherein the anode contact or the cathode contact is opaque and metallic to the generated laser radiation. 18. Method for manufacturing a semiconductor laser according to one of the previous aspects with the following steps: - Providing the semiconductor laser chip, and - Attaching the diffractive optical element to the semiconductor laser chip or shaping the diffractive optical element in the semiconductor laser chip.

[0065] The following section provides a more detailed explanation of a semiconductor laser and a method described herein, with reference to the drawing and illustrated by exemplary embodiments. Identical reference symbols indicate identical elements in the individual figures. However, the figures are not to scale; rather, individual elements may be exaggerated for clarity.

[0066] They show: Fig. Figures 1 to 4, 15 and 16 are schematic sectional views of process steps of exemplary embodiments of the processes described here. Fig. Figures 5 to 13, 14B and 17 are schematic sectional views of exemplary embodiments of semiconductor lasers described herein, and Fig. Figure 14A is a schematic top view of an embodiment of a semiconductor laser described herein.

[0067] In Fig. Figure 1 illustrates an embodiment of a manufacturing process for a surface-mountable semiconductor laser 1 described herein. Fig. In 1A, a support substrate 32 is provided for a diffractive optical element 3. The support substrate 32 is, for example, a sapphire substrate.

[0068] A separating layer 34 is produced on the support substrate 32, for example by epitaxial growth. The separating layer 34 is, for example, a GaN layer. Furthermore, a raw material layer 35 is deposited on the separating layer 34, for example by epitaxial growth or sputtering. The raw material layer 35 is, for example, made of aluminum nitride.

[0069] In the procedural step of Fig. In step 1B, an optically active structure 33 is formed in the raw material layer 35. The optically active structure 33 is produced, for example, by lithography and etching. For example, the optically active structure 33 exhibits, in Fig. The optically effective structure 33 is symbolized by hatching and, viewed from above, has a grid-like form. The structural dimensions of the optically effective structure 33, viewed from above, are, for example, in the range of one-quarter or one-half of the wavelength of the laser radiation L generated during operation of the finished semiconductor laser 1. The same applies to the thickness of the optically effective structure 33, which is alternatively or additionally less than or equal to 2 µm or 1 µm. The optically effective structure 33 only partially penetrates the raw material layer 35. Here and in the following, the optically effective structure 33 is illustrated in a highly simplified manner.

[0070] In plan view, the optically effective structure 33 preferably has structural elements with an average size of at least 0.5 µm to 1 µm. The height of the structural elements depends on the planned refractive index difference between the optically effective structure 33 and its surroundings and should be sufficiently large to achieve the required optical path difference via a phase shift.

[0071] In the procedural step of Fig. In 1C, a semiconductor laser chip 4 is provided. The semiconductor laser chip 4 is a surface-emitting laser. The semiconductor laser chip 4 has a growth substrate 2 for a semiconductor layer sequence 40. The semiconductor layer sequence 40 has a growth direction G in the direction away from the growth substrate 2. Furthermore, the semiconductor layer sequence 40 includes at least one active zone 41 for generating the laser radiation L. A light-emitting surface 44 of the semiconductor laser 4 is formed by the semiconductor layer sequence 40 and is oriented perpendicular to the growth direction G.

[0072] The growth substrate 2, for example, is a GaAs substrate. The semiconductor layer sequence 40 is based in particular on the AlInGaAs material system. This differs from the representation in Fig. 1. It is possible that a substitute substrate is used instead of the growth substrate 2, onto which the semiconductor layer sequence 40 is applied after growth. In this case, the growth substrate 2 is removed.

[0073] In the procedural step of Fig. 1D will be the component made of Fig. 1B onto the semiconductor laser chip 4 from Fig. 1C is applied. This is done via a layer of a bonding agent 5. The bonding agent 5, which is transparent to the laser radiation L, extends across the entire surface and continuously between the semiconductor laser chip 4 and the component made of Fig. 1B. The bonding agent 5 is, for example, an organic adhesive. It is possible that the bonding agent 5 fills the optically active structure 33 made of the high-refractive-index material. Due to the high refractive index of the optically active structure 33, a sufficiently large refractive index difference to the bonding agent 5 is maintained so that the optically active structure 33 achieves the desired effect.

[0074] According to Fig. In step 1E, only the optically active structure 33 remains on the semiconductor laser 4. This is achieved, in particular, by a laser lifting process through the support substrate 32. Specifically, laser radiation is directed through the support substrate 32, which decomposes the separating layer 34, so that the support substrate 32 can be lifted off. Alternatively or additionally to a laser lifting process, etching and / or grinding and / or polishing can also be performed. Optionally, any remaining traces of the separating layer 34 on the optically active structure 33 are removed. The excess raw material layer 35 is also optionally completely removed.

[0075] The separating layer 34 ultimately serves to remove the support substrate 32 by means of a lifting process such as laser lifting. As explained, the separating layer 34 can be a semiconductor layer, but this is not strictly necessary. For removal, it is only required that the separating layer 34 be partially or completely degradable by a method such as laser degradation or etching. Therefore, a dielectric and / or an organic material such as polymerized bisbenzocyclobutene, or BCB for short, can also be used for the separating layer 34.

[0076] In the procedural step of Fig. Figure 1F shows that the semiconductor layer sequence 40 is exposed in certain areas, with the connecting element 5 and the optically active structure 33, which forms the diffractive optical element 3, being removed in certain areas. In the exposed area of ​​the semiconductor layer sequence 40, electrical contacts 91, 92, can be placed. Fig. 1F is only illustrated in a highly simplified manner, to power the active zone 41.

[0077] Alternatively to the representation in Fig. 1. The diffractive optical element 3 can already be used before the process step of Fig. 1D, for example during the step of Fig. 1B, which is in Fig. Figure 1F shows a recess for the electrical contacts 91, 92. The same applies to all other embodiments.

[0078] In the process of Fig. 2. First, a semiconductor laser chip 4 is provided, see Fig. 2A. Subsequently, the raw material layer 35 is deposited on the light-emitting surface 44, see Fig. 2B. The raw material layer 35, for example, consists of deposited amorphous aluminum oxide.

[0079] Then, see Fig. 2C, the optically active structure 33 is created in the raw material layer 35. The optically active structure 33 does not extend to the light-emitting surface 44. Alternatively, unlike in Fig. As shown in Figure 2C, the optically effective structure 33 can also extend to the semiconductor layer sequence 40.

[0080] In Fig. In 2D, it is shown that the semiconductor layer sequence 40 is partially exposed to enable electrical contacting, analogous to Fig. 1F.

[0081] In Fig. 3A is provided in a further exemplary manufacturing process of the semiconductor laser chip 4. Furthermore, the optically active structure 33 is provided on the support substrate 32. The optically active structure 33 can be composed of two substructures 33a, 33b, which are Fig. 3 are symbolized by different hatching patterns. Such an optically effective structure 33 with several substructures can also be used in all other embodiments. More than two substructures may be present.

[0082] In Fig. 3B shows that the two components from Fig. 3A are attached to each other via the connecting element 5 and that part of the semiconductor layer sequence 40 is exposed for electrical contacting.

[0083] Unlike in the Fig. 1 and Fig. 2 shows the diffractive optical element 3 in the finished semiconductor laser 1 of the Fig. The remaining raw material layer 35, the optional separating layer 34, and the support substrate 32 are also included. The laser radiation L is emitted through the layer with the bonding agent 5, the optically active structure 33, the raw material layer 35, the optional semiconductor layer 34, and the support substrate 32. The support substrate 32 is preferably sapphire or silicon carbide. In all other embodiments, it is also possible in principle for the support substrate 32 to still be present in the finished semiconductor laser 1.

[0084] In the process of Fig. 4. The raw material layer 35 is produced directly on the support substrate 32. The support substrate 32 is, for example, GaAs, and the raw material layer 35 is, for example, made of AlP. According to Fig. 4B creates the optically effective structure 33 in the raw material layer 35.

[0085] In Fig. Figure 4C shows that a planarization layer 37 is applied to planarize the optically active structure 33. The planarization layer 37, 5a is used for the subsequent connection with the in Fig. The semiconductor laser chip 4 provided in 4D is required. The two layers 5a, 5b on the diffractive optical element 3 and on the semiconductor laser chip 4 are made of SiO2 and are polished, for example, chemomechanically, before preferably by blasting, see Fig. 4E. Thus, layers 5a and 5b together form the bonding layer 5.

[0086] Optional, see Fig. 4F, the carrier substrate 32 is removed. As in Fig. In 1F, the semiconductor layer sequence 40 is exposed in certain places for electrical contacting.

[0087] According to Fig. In particular, an AlP layer is structured directly onto the GaAs substrate, subsequently flattened, and bonded to the semiconductor laser chip 4 via a process such as direct bonding. As in all other embodiments, flowable oxides (FOX) can be used as the bonding agent 5. Organic materials such as cross-linked dibenzocyclobuthene layers can also be used.

[0088] In the Fig. 1, Fig. 2, Fig. 3 to Fig. Figure 4 illustrates the application of only one diffractive optical element 3 onto only one semiconductor laser chip 4. In contrast, the following can be used in the Fig. 1, Fig. 2, Fig. 3 to Fig. 4. A wafer-to-wafer process can also be used to simultaneously deposit a large number of diffractive optical elements 3 onto a large number of semiconductor laser chips 4. The respective methods of the Fig. 1, Fig. 2, Fig. 3 to Fig. Four processes can therefore be carried out in a wafer-to-wafer process, a chip-to-wafer process, or a chip-to-chip process. A wafer-to-wafer process is preferred for efficiency reasons.

[0089] Furthermore, unlike in Fig. As shown in section 4, it is possible that, analogously to Fig. 1. Instead of direct bonding, an adhesive is used to bond the two components from the Fig. 4C and Fig. to join the 4D components together. In this case, the layer with the bonding agent 5 is preferably realized as a single layer. Adhesive bonding, pressure bonding, or direct bonding can also be used as alternative methods for joining the two components together in all other embodiments.

[0090] As a further alternative to the procedure of Fig. 4. It is possible that the raw material layer 35 is first applied to the semiconductor laser chip 4 on the support substrate 32, see Fig. 4G, and that the optically effective structure 33 is only created after the detachment of the carrier substrate 32, see Fig. 4H. Since the creation of the optically effective structure 33 only takes place on the semiconductor chip 4, only a comparatively rough pre-adjustment of the component is possible. Fig. 4G relative to the semiconductor laser 4 is needed.

[0091] In the exemplary embodiment of the Fig. Figure 5 shows that several semiconductor laser chips 4 are present. The diffractive optical element 3 extends in one piece and together across the semiconductor laser chips 4. For example, the diffractive optical element 3 and the semiconductor laser chips 4 are contacted with each other via wafer bonding while still within the wafer assembly, thus forming a joining area 39. The diffractive optical element 3 is located on the side of the growth substrate 2 facing away from the semiconductor layer sequence 40. The electrical contacts 91, 92 are located laterally next to the semiconductor layer sequence 40 with the active zone 41. Optionally, a singulation process (not shown) can be carried out to form separate semiconductor lasers 1, each with one or more semiconductor laser chips 4.

[0092] Optionally, the planarization layer 37 is present on one side of the diffractive optical element 3 facing away from the semiconductor layer sequence 40, as is also possible in all other embodiments in which the optically effective structure 33 is located on an outside.

[0093] In the Fig. 6 and Fig. Figure 7 illustrates that the optically active structure 33 is formed directly in the growth substrate 2. According to Fig. In this embodiment, the electrical contacts 91, 92 are designed such that they partially extend within the semiconductor layer sequence 40, with one of the contacts 92 penetrating the plane containing the active zone 41. As in all other embodiments, a Bragg mirror 46 is possible between the area containing the active zone 41 and the growth substrate 2. The planarization layer 37 is again optionally present.

[0094] The refractive index of silicon nitride is often estimated to be above 2. Using plasma-enhanced chemical vapor deposition, SiN:H layers with lower refractive indices can be produced, for example, approximately 1.85 at 633 nm. The optically active structure 33 of the Fig. 6 is made especially of SiN:H or also of sapphire.

[0095] In Fig. 7. The growth substrate 2 and the diffractive optical element 3 are monolithically integrated, instead of using separate diffractive optical elements, as is the case, for example, in connection with the Fig. 1, Fig. 3, Fig. 4 or Fig. 5 illustrated.

[0096] In Fig. Figure 8 illustrates that the electrical contacts 91, 92 are located on opposite sides of the growth substrate 2. A corresponding design can also be used in all other embodiments.

[0097] In Fig. Figure 9 shows that the diffractive optical element 3 is applied to the side with the semiconductor layer sequence 40. It is possible that the diffractive optical element 3 projects laterally beyond the respective semiconductor layer sequence 40, i.e., in a direction perpendicular to the growth direction G, or, unlike the drawing, that it is flush with the semiconductor layer sequence 40. Furthermore, as in all other embodiments, it is possible that one of the electrical contacts 92 is applied over a surface.

[0098] In the exemplary embodiment of the Fig. In addition, a potting material 7 is present in 10. The diffractive optical element 3 is primarily attached via the bonding agent 5, for example, an adhesive or a flowable oxide. The potting material 7 extends in some places to a side of the diffractive optical element 3 facing the semiconductor laser chip 4 and is in direct contact with the optically active structure 33 in some places.

[0099] In contrast, according to Fig. 10B, the diffractive optical element 3 is attached via the potting material 7, which simultaneously serves as the connecting element 5. The potting material 7 protects the semiconductor laser 1 against external influences. Due to the high refractive index of the optically active structure 33, it is harmless if the potting material 7 covers and / or fills the optically active structure 33.

[0100] In the Fig. 10A and Fig. Figure 10B points the optically active structure 33 towards or away from the semiconductor laser chip 4. Both possible arrangements of the optically active structure 33 can be used analogously.

[0101] In Fig. Figure 11A shows that the bonding agent 5 is applied in a frame-like manner to the light-emitting surface 44, wherein an area directly above the active zone 41, which is configured to generate the laser radiation, is preferably free of the bonding agent 5. For example, the bonding agent 5 is a metal layer, so that the diffractive optical element 3 can be joined to the semiconductor laser chip 4, for example, by soldering, such as eutectic, quasi-eutectic, or isothermal solidification. The bonding agent 5 can be composed of several sublayers.

[0102] In Fig. 11A, the connecting element 5 partially engages in the optically effective structure 33. In contrast, according to Fig. 11B the optically effective structure 33 is limited to an area above the active zone 41. Thus, the connecting element 5 is spaced away from the optically effective structure 33.

[0103] In Fig. 11A as well as in Fig. In 11B, a gap 6 is located between the diffractive optical element 3 and the semiconductor laser chip 4. The gap 6 is relatively thin and, for example, filled with air.

[0104] According to Fig. 11. A comparatively precise adjustment is carried out in order to achieve an exact alignment of the diffractive optical element 3 with the connecting element 5, which is designed in particular as a metal frame.

[0105] In Fig. Figure 12 shows that the connecting element 5 is spaced apart from the semiconductor layer sequence 40. The connecting element 5, for example a metal pedestal, is in direct contact with the growth substrate 2 and with the diffractive optical element 3.

[0106] In contrast, see Fig. In Figure 12B, the connecting element 5 is mounted on a mounting carrier 8 and is not in direct contact with the semiconductor laser chip 4. The diffractive optical element 3 completely covers the semiconductor laser chip 4. A gap 6 is formed between the connecting element 5, the semiconductor laser chip 4, and between the semiconductor laser chip 4 and the diffractive optical element 3.

[0107] According to Fig. In section 13A, several semiconductor laser chips 4 are mounted on the mounting carrier 8. The semiconductor laser chips 4 are jointly covered by the single-piece, continuous diffractive optical element 3. The diffractive optical element 3 can project laterally beyond the semiconductor laser chips 4.

[0108] In contrast, according to Fig. 13B the diffractive optical element 3 itself a carrier for the semiconductor laser chips 4. For this purpose, the diffractive optical element 3 can be provided with electrical contact structures, not shown.

[0109] According to Fig. 13 The semiconductor laser 1 has several semiconductor laser chips 4, as can also be the case in all other embodiments. Likewise, in each of the embodiments it is possible that there is only one or several semiconductor laser chips 4, which can have several laser areas or individual lasers 47, for example an array of surface-emitting vertical resonator lasers, also called a VCSEL array, see the top view in Fig. 14A and the sectional view in Fig. 14B. The individual lasers 47, which in plan view are arranged, for example, in a hexagonal, rectangular or square pattern, can be controlled individually or can only be operated together.

[0110] In the manufacturing process of Fig. In step 15, the semiconductor laser 1 is fabricated as a flip chip on a transparent support substrate 32, for example made of glass, BF33 or sapphire. A planar diffractive optical element 3 is deposited onto the support substrate 32.

[0111] According to Fig. In step 15A, the semiconductor layer sequence 40 is epitaxially grown on the growth substrate 2, for example, made of GaAs. The semiconductor layer sequence 40 comprises, from the growth substrate 2, a first Bragg mirror 46a, the region with the active zone 41, and a second Bragg mirror 46b. Both Bragg mirrors 46a and 46b are preferably electrically conductive and comprise alternating layers with high and low refractive indices.

[0112] In Fig. Figure 15B shows that a bonding layer 93 and the anode contact 91 are formed on the second Bragg mirror 46b. The bonding layer 93 is, for example, made of SiO2, and the anode contact 91 is preferably made of one or more metal layers. In the direction away from the second Bragg mirror 46a, the anode contact 91 and the bonding layer 93 preferably terminate flush with each other.

[0113] In the step of the Fig. In step 15C, the transparent support substrate 32 is applied to the bonding layer 93 by means of wafer bonding. In this step, the optically active structure 33 can already be located on the support substrate 32, or the optically active structure 33 can be attached to the support substrate 32 later.

[0114] Wafer bonding, for example, is a direct bonding process using SiO2 on SiO2. The optically active structure 33 can be lithographically applied, particularly after removal of the growth substrate 2 and after wafer bonding, thereby achieving high accuracy. Preferably, the planarization layer 37 is applied to the optically active structure 33, so that the optically active structure 33 is buried and not exposed on the outside.

[0115] In Fig. In step 15D, the first Bragg mirror 46a is partially removed, exposing the region of the semiconductor layer sequence 40 with the active zone 41. Preferably, a current constriction 48 is also created, for example by oxidation. Thus, the active zone 41 is only energized in the region of the current constriction 48, since the semiconductor layer sequence 40 in the region of the active zone 41 exhibits only low electrical conductivity in the direction parallel to the active zone 41.

[0116] Finally, as in Fig. Figure 15E shows a filling material 94 applied, into which the first Bragg mirror 46a is embedded. The filling material 94 is electrically insulating and is, for example, a spin-on glass or an organic material such as benzocyclobutene, or BCB for short.

[0117] A preferably metallic via 95 is then created through the filler material 94 and through the second Bragg mirror 46b. The via 95 electrically connects the anode contact area 91 to the bonding layer 93. Similarly, the first Bragg mirror 46a is electrically contacted via a metallization. This contact of the first Bragg mirror 46a is preferably reflective to the laser radiation generated during operation. Thus, the first Bragg mirror 46a, together with this contact, is a metal-Bragg hybrid mirror. This allows the first Bragg mirror 46a to have fewer layer pairs, for example, a maximum of 12 layer pairs or a maximum of 6 layer pairs.

[0118] Finally, electrical contact pads for the two contacts 91 and 92 are prepared. These contact pads can cover a large area of ​​the filler material 94. The contact pads lie in a common plane, making the semiconductor laser 1 an SMT component and thus surface-contactable.

[0119] The procedural step of Fig. 16A is carried out analogously to the step of Fig. 15A. In deviation from Fig. However, 15B is used in Fig. 16B the second Bragg mirror 46b is structured so that the area of ​​the semiconductor layer sequence 40 with the active zone 41 is exposed from a side facing away from the growth substrate 2. In addition, the current constriction 48 is created in the second Bragg mirror 46b.

[0120] The filler material 94 is then optionally applied over the entire surface. Subsequently, the anode contact 91 and the bonding layer 93 are created, and the diffractive optical element 3 is attached, analogous to the Fig. 15B and Fig. 15C.

[0121] Finally, the growth substrate 2 is removed, see Fig. 16D.

[0122] According to Fig. In 16E, the via 95 is routed through the first Bragg mirror 46a and through the filler material 94 to the anode contact 91 on the bonding layer 93. An additional filler material 94 can be used for electrical insulation of the via 95 from the first Bragg mirror 46a.

[0123] Finally, the contact surfaces for contacts 91 and 92 are produced. This is preferably done in the same way as described above in conjunction with Fig. 15E explained.

[0124] The procedures of Fig. 15 and Fig. 16 differ primarily in the position of the current constriction 48. Consequently, either only the first or only the second Bragg mirror 46a, 46b is penetrated by the via 95.

[0125] In contrast, in the exemplary embodiment of the Fig. 17 The via 95 passes through both Bragg mirrors 46a, 46b. Preferably, one of the current constrictions 48 is present in each of the Bragg mirrors 46a, 46b. For this purpose, both Bragg mirrors 46a, 46b are structured. Only the area of ​​the semiconductor layer sequence 40 with the active zone 41 remains completely intact, except for the area with the via 95. In other words, the exemplary embodiment of Fig. 17 a combination of the methods of Fig. 15 and Fig. 16 dar.

[0126] As in all other embodiments, the anode contact 91 and the cathode contact 92 can be interchanged with respect to their electrical polarity.

[0127] The diffractive optical element in the semiconductor lasers 1 described here enables a higher integration density. Cost reduction is also achievable through wafer-level integration of the VCSEL 4 and optics 3. Precisely fitting optics can be attached, resulting in inherently eye-safe components. Flip chips with good thermal interfaces can be produced. Overall, high alignment accuracy between the VCSEL chip 4 and the optics 3 is possible through wafer-level alignment, while simultaneously reducing costs.

[0128] Furthermore, the composite of the VCSEL chip 4 and the optics 3 is suitable for further processing, for example by potting and / or embedding in other materials. This applies in particular to a planar integrated optically active structure 33 within the support substrate 32.

[0129] Unless otherwise indicated, the components shown in the figures preferably follow one another in the specified order. Layers that do not touch each other in the figures are spaced apart. Where lines are drawn parallel to each other, the corresponding surfaces are also parallel to each other. Also, unless otherwise indicated, the relative thickness ratios, length ratios, and positions of the drawn components are correctly represented in the figures.

[0130] The invention described here is not limited by the description based on the exemplary embodiments. Rather, the invention encompasses every new feature as well as every combination of features, which in particular includes every combination of features in the patent claims, even if this feature or combination itself is not explicitly specified in the patent claims or exemplary embodiments.

[0131] This patent application claims priority over German patent application 10 2017 100 997.3, the disclosure content of which is hereby incorporated by reference. Reference symbol list 1 semiconductor laser 2. Growth substrate 3 diffractive optical element 32 Carrier substrate 33 optically effective structures 34 Semiconductor layer 35 Raw material layer 37 Planarization layer 39 Joining area 4 semiconductor laser chips 40 semiconductor layer sequence 41 active zone 44 Light emission area 46 Bragg mirrors 47 individual lasers 48 Current restriction 5 Fasteners 6 columns 7 Potting compound 8 mounting brackets 91 Anode contact 92 Cathode contact 93 Bond layer 94 Filling material 95 Through-hole plating G Growth direction L Laser radiation

Claims

[1] Semiconductor laser (1) with - at least one surface-emitting semiconductor laser chip (4) comprising a semiconductor layer sequence (40) with at least one active zone (41) for generating laser radiation (L) and comprising a light-emitting surface (44) oriented perpendicular to a growth direction (G) of the semiconductor layer sequence (4) and at which the semiconductor laser chip (4) emits the laser radiation (L), and - a diffractive optical element (3) configured to expand and disperse the laser radiation (L), wherein - an optically effective structure (33) of the diffractive optical element (3) made of a material with a refractive index of at least 1.65, based on a wavelength of maximum intensity of the laser radiation (L), - the optically effective structure (33) is located on a side of the diffractive optical element (3) facing the semiconductor laser chip (4), and - a connecting means (5) for the diffractive optical element (3) is located at an edge of the diffractive optical element (3), such that the light exit surface (44) is at least partially free of the connecting means (5) and such that a gap (6) is formed at least partially between the diffractive optical element (3) and the light exit surface (44); wherein (i) the connecting element (5) is applied directly to the light-emitting surface (44) in a frame-like manner and is in direct contact with the diffractive optical element (3); or (ii) the semiconductor laser chip (4) has a growth substrate (2) on which the semiconductor layer sequence (40) is epitaxially grown, wherein the connecting means (5) and the semiconductor layer sequence (40) are arranged laterally spaced apart from each other on the growth substrate (2) and wherein the connecting means (5) is in direct contact with the growth substrate (2) and the diffractive optical element (3). [2] Semiconductor laser (1) according to claim 1, wherein a region directly above the active zone (41) is free of the connecting medium (5). [3] Semiconductor laser (1) according to any of the preceding claims, wherein the gap (6) is filled or evacuated with a gas. [4] Semiconductor laser (1) according to one of the preceding claims, wherein the diffractive optical element (3) projects laterally beyond the semiconductor laser chip (4). [5] Semiconductor laser (1) according to one of the preceding claims, wherein the diffractive optical element (3) comprises a support substrate (32), wherein the optically effective structure (33) is located on a side of the support substrate (32) facing the light exit surface (44). [6] Semiconductor laser (1) according to the preceding claim, wherein the optically active structure (33) is made of a semiconductor material, the support substrate (32) being a growth substrate for the semiconductor material of the optically active structure (33). [7] Semiconductor laser (1) according to one of the preceding claims, wherein the distance between the diffractive optical element (3) and the semiconductor laser chip (4) is at most ten times the wavelength of maximum intensity of the laser radiation (L). [8] Semiconductor laser (1) according to one of the preceding claims, wherein the optically effective structure (33) of the diffractive optical element (3) is made of a material having a refractive index of at least 2.

0. [9] Semiconductor laser (1) according to any one of the preceding claims, in which the semiconductor layer sequence (40) includes at least one Bragg mirror (46a, 46b), wherein the Bragg mirror (46a, 46b) is penetrated by an electrical via (95) and electrical connection surfaces are located on a common side of the active zone (41), so that the semiconductor laser (1) is surface-mountable, and wherein a current constriction (48) is generated in the Bragg mirror (46a, 46b) such that the active zone (41) is only energized in at least one current-passing region of the current constriction (48) during operation. [10] Semiconductor laser (1) according to the preceding claim, comprising two of the Bragg mirrors (46a, 46b) located on different sides of the active zone (41), each of the Bragg mirrors (46a, 46b) being penetrated by the via (95). [11] Semiconductor laser (1) according to any one of the preceding claims, in which an anode contact (91) or a cathode contact (92) extends between the semiconductor layer sequence (40) and the diffractive optical element (3), such that the light exit surface (44) is surrounded on a side facing the diffractive optical element (3) in top view by a material of the anode contact (91) or the cathode contact (92), wherein the anode contact (91) or the cathode contact (92) is opaque and metallic to the generated laser radiation (L). [12] Method for manufacturing a semiconductor laser (1) according to any one of the preceding claims comprising the steps: - Provision of the semiconductor laser chip (4), and - Attaching the diffractive optical element (3) to the semiconductor laser chip (4).

Images