Phase-coupled laser assembly and method for producing a phase-coupled laser assembly

A laser device is provided which comprises a common waveguide layer and a plurality of laser bodies, wherein each of the laser bodies has an active region configured for generating coherent electromagnetic radiation. The laser bodies are arranged side by side on the common waveguide layer, wherein the laser bodies are directly adjacent to the common waveguide layer. In particular, the laser bodies are configured to be phase-coupled to each other via the waveguide layer during operation of the laser device.Furthermore, a method for producing such a phase-coupled laser device is provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a national stage entry from International Application No. PCT/EP2019/071464, filed on Aug. 9, 2019, published as International Publication No. WO 2020/057856 A1 on Mar. 26, 2020, and claims priority under 35 U.S.C. § 119 from German patent application 10 2018 123 320.5, filed Sep. 21, 2018, the entire contents of all of which are incorporated by reference herein.

A laser device is provided which is configured in particular to be phase-coupled. Furthermore, a method for producing a laser device, in particular a phase-coupled laser device, is provided.

For generating a structured far field in the form of a diffraction pattern, an emitter array with imaging optics is usually used. The use of several single emitters with complex optics is usually elaborate and cost-intensive. For varying the direction of the diffraction pattern, movable optical elements or complex housings are usually used.

One object is to specify a compact laser device that can be manufactured in a simplified manner, in particular for generating a structured far field of a point lattice. Another object is to specify a cost-effective method for producing a laser device, in particular a laser device described here.

These objects are solved by the laser device according to the independent claim as well as by the method for producing a laser device. Further embodiments of the laser device or of the method for producing a laser device are the subject-matter of the further claims.

A laser device having a common waveguide layer is disclosed. The laser device has a plurality of laser bodies arranged on the common waveguide layer. In particular, the laser bodies are directly adjacent to the waveguide layer. It is possible that the laser bodies and the waveguide layer are formed as one piece. Particularly preferably, the common waveguide layer and the laser bodies or at least parts of the laser bodies and the common waveguide layer are formed from one piece. In this sense, the laser device comprising the common waveguide layer and the plurality of laser bodies is in particular formed monolithically. For example, there is a smooth continuous transition between the common waveguide layer and the laser bodies.

According to at least one embodiment of the laser device, each of the laser bodies has an active zone that is configured in particular for generating coherent electromagnetic radiation. For example, the active zone of the respective laser body is provided for generating electromagnetic radiation in the infrared, visible or ultraviolet spectral range. The laser bodies may be based on a III-V or on a II-VI compound semiconductor material. For example, each of the laser bodies has a semiconductor body comprising the active region based on such a compound semiconductor material. The semiconductor bodies of the laser bodies may be based on the same compound semiconductor material.

Different semiconductor layers or bodies are based on the same compound semiconductor material if these layers or bodies have at least one identical element, for example from main group II or III, and another identical element, for example from group VI or V. In addition to the two identical elements, the semiconductor layers or bodies may have additional elements, in particular from the same groups or from other groups to form binary, tertiary or quaternary compounds. For example, the layers of the laser bodies and the layers of the common waveguide layer are based on an arsenide, nitride, phosphide, sulfide, or selenide compound semiconductor, such as GaN, InP, ZnS, or ZnSe compound semiconductors. In addition to the active region, the semiconductor body may comprise a first semiconductor layer and a second semiconductor layer, with the active region disposed between the semiconductor layers. In particular, the active region is a pn-junction of the semiconductor body or of the laser body.

According to at least one embodiment of the laser device, the laser bodies are arranged next to each other on the common waveguide layer. In lateral directions, the laser bodies may be spatially spaced apart from each other. For example, the laser bodies are grown, in particular epitaxially grown, on the common waveguide layer. The laser bodies may have identical structure. Within manufacturing tolerances, the laser bodies may be configured to generate electromagnetic radiation of the same wavelength. In particular, the laser bodies are configured to generate single-mode radiation.

A lateral direction is understood to be a direction directed parallel for instance to a main extension surface of the common waveguide layer. A vertical direction is understood to be a direction that is perpendicular in particular to the main extension surface of the common waveguide layer. In particular, the vertical direction and the lateral direction are orthogonal to each other.

According to at least one embodiment of the laser device, via the common waveguide layer during operation of the laser device, the laser bodies are formed to be phase-coupled to each other. If the laser bodies are formed to be phase-coupled to each other, at least the main modes of the radiations emitted by the laser bodies or by the semiconductor bodies have a constant or substantially constant phase relationship to each other during operation of the laser device. The laser bodies can be phase-coupled to each other, in particular truly phase-coupled to each other, if a predetermined lateral distance between adjacent laser bodies is maintained. The predetermined distance depends in particular on the peak wavelength of the emitted electromagnetic radiation and on the refractive index of the common waveguide layer. It is possible that active elements are integrated or formed in the waveguide layer which are configured to change the refractive index, in particular to change the local refractive index of the common waveguide layer.

In at least one embodiment, the laser device comprises a common waveguide layer and a plurality of laser bodies. The laser bodies each have an active region configured to generate coherent electromagnetic radiation. The laser bodies are arranged side by side on the common waveguide layer. Particularly preferably, the laser bodies are directly adjacent to the common waveguide layer. In operation of the laser device, the laser bodies are formed to be phase-coupled to one another, in particular via the waveguide layer.

Particularly preferably, the laser bodies and the common waveguide layer are of monolithic form. For example, the laser bodies each have the shape of a surface-emitting laser diode, such as a VCSEL (vertical-cavity surface-emitting laser). In particular, the radiation emitted during operation emerges vertically along a vertical direction from the corresponding laser body. For instance, the laser device has a plurality of laser bodies, each of which has an aperture, the aperture being formed on a surface of the respective laser body facing away from the common waveguide layer. An aperture is in particular an exit aperture of the radiation emitted during operation of the laser body.

In virtue of the one-piece or monolithically formed laser device comprising of a plurality of laser bodies and a common waveguide layer, wherein the electromagnetic radiations generated by the laser bodies are phase-coupled to each other, a particularly compact component can be provided which is particularly suitable for generating a structured far field in the form of a diffraction pattern of a one-dimensional or two-dimensional point lattice. With such a monolithically integrated component, moreover, the radiation direction can be controlled in a simplified manner, in particular by electrical signals. In this case, it is not necessary to use movable optical elements or complex housings to vary the direction. The variation of direction or the adjustment of the radiation direction of the laser device can be achieved by targeted phase coupling of the laser bodies, for example by local electrical control and/or by local adjustment of the refractive index of the common waveguide layer.

According to at least one embodiment of the laser device, the laser bodies each have a sublayer directly adjacent to the common waveguide layer. The sublayers of the laser bodies and of the common waveguide layer may be formed from the same material or, at least at a transition region, from the same material. In particular, there is a smooth transition region between the common waveguide layer and the laser body sublayers. For example, the laser bodies, in particular the sublayers of the laser bodies, are directly grown on the common waveguide layer. It is possible that originally, the sublayers of the laser bodies are integral parts of the common waveguide layer which are assigned to the laser bodies during the course of the production of the laser bodies. In particular, the laser bodies are local vertical elevations on the common waveguide layer.

According to at least one embodiment of the laser device, it has a common carrier on which the common waveguide layer is arranged. In the vertical direction, the common waveguide layer is arranged in particular between the common carrier and the laser bodies. Preferably, the laser device is mechanically stabilized and thus mechanically supported by the common carrier. In particular, the common carrier has a higher mechanical stability than the common waveguide layer. The common carrier may be formed from an electrically insulating material, an electrically conductive material, or from a semiconductor material. For example, the common carrier is a ceramic body, a semiconductor body or a metal body. In particular, the common carrier is different from a growth substrate on which the common waveguide layer and/or the plurality of laser bodies are/is epitaxially grown. However, it is also conceivable that the common carrier is a growth substrate which is, for example, a sapphire substrate or a semiconductor substrate.

According to at least one embodiment of the laser device, it has a coupling layer comprising a plurality of coupling structures. The coupling layer is arranged in particular on a rear side of the common waveguide layer facing away from the laser bodies. In a top view of the common waveguide layer, the coupling structures may be covered, in particular completely covered, by the laser bodies. If the radiation emitted by a laser body is coupled into the common waveguide layer along the vertical direction, at the coupling structures, the electromagnetic radiation can be redirected in a lateral direction. By propagating laterally, the electromagnetic radiation can cause phase coupling between the laser bodies to occur. For example, a stationary wave field can be formed in the common waveguide layer which provides a defined phase coupling of the laser bodies, in particular of all laser bodies of the laser device.

According to at least one embodiment of the laser device, the coupling structures extend into the common waveguide layer. In particular, the coupling structures are formed to be reflective for the electromagnetic radiation generated by the laser bodies during operation of the laser device. For example, the coupling structures are each provided with a reflective layer or formed from a radiation-reflective material. It is possible that the coupling structures are formed with respect to the material composition of the common waveguide layer in such a way that total reflections take place or are favored at the coupling structures. The coupling layer may be formed of an electrically insulating material or of an electrically conductive material. If the coupling layer is formed to be electrically conductive, the coupling layer can serve as a contact layer for the laser device, in particular for the common waveguide layer or for the laser bodies.

According to at least one embodiment of the laser device, during operation of the laser device, a lateral distance between adjacent laser bodies is m·λ/n, where m is an integer natural number, λ is the wavelength of radiation coupled into the common waveguide layer and n is the refractive index of the common waveguide layer. In other words, the lateral distance between the adjacent laser bodies is a multiple of the wavelength of the radiation coupled into the common waveguide layer. In particular, the lateral distance is the path length or coupling distance between the adjacent laser bodies. Since m is any integer, the lateral distances between the different adjacent laser bodies may be the same or different.

According to at least one embodiment of the laser device, electrically controllable active elements are integrated or formed in the common waveguide layer. The active elements are preferably configured for local adjustment of the refractive index of the common waveguide layer. This may be necessary, for example, if due to manufacturing tolerances the coupling path or the optical path length is not a multiple of the wavelength. The active element may be integrated in the form of a Wannier-Stark modulator in the waveguide layer. Due to an electric field applied to the common waveguide layer, such a modulator can cause a change in the refractive index, in particular a change in the local refractive index of the common waveguide layer. In this way, the coupling path or optical path length between the adjacent laser bodies can be corrected during operation of the laser device. The active elements integrated or formed in the common waveguide layer thus serve to control the refractive index or to adjust the refractive index of the common waveguide layer.

According to at least one embodiment of the laser device, the common waveguide layer comprises an active region which is in particular located in the coupling path of the waveguide layer. The common waveguide layer may comprise a first sublayer and a second sublayer, wherein the active region is arranged in the vertical direction between the first sublayer and the second sublayer. For example, the active region of the common waveguide layer is configured to generate electromagnetic radiation. The waveguide layer having the active region may serve as an optical amplifier.

Alternatively or additionally, it is possible that the active region is configured to adjust the local refractive index of the common waveguide layer. In particular, the active region forms a sub-region of the active element or active elements integrated or formed in the common waveguide layer.

According to at least one embodiment of the laser device, the active region of the common waveguide layer is implemented as an active quantum well layer of a Wannier-Stark modulator. In particular, during operation of the laser device, due to an applied electric field, the modulator causes a change of the refractive index, especially a local adjustment of the refractive index of the common waveguide layer.

According to at least one embodiment of the laser device, the laser bodies are arranged in at least one row on the common waveguide layer. The laser device may include a plurality of rows and columns of the laser bodies on the common waveguide layer. For example, the laser bodies form a matrix-like array of the laser bodies on the common waveguide layer. The row or column of the laser bodies may have a laser body arranged at one edge, which is formed in particular as a guiding laser body. For example, the guiding laser body is configured such that out from the guiding laser body, electromagnetic radiation emitted by the guiding laser body can be coupled exclusively in the direction of the common waveguide layer. The radiation coupled into the common waveguide layer can propagate along the common waveguide layer and stimulate the other laser bodies to emit phase-coupled electromagnetic radiation. The other laser bodies, in particular those stimulated by the guiding laser body, can be both electrically and optically pumped, for example optically pumped by the radiation generated by the guiding laser body.

On its surface facing away from the common waveguide layer, the guiding laser body can have a radiation-reflecting layer, which in particular completely covers the guiding laser body and thus prevents the out-coupling of the radiation at this surface. The radiation-reflecting layer can be formed as a radiation non-transmissive contact layer of the guiding laser body. If electromagnetic radiation is generated in the guiding laser body, it is reflected back at the radiation-reflecting layer towards the waveguide layer and coupled into the common waveguide layer. The guiding laser body arranged at the edge can thus predefine the phase of the radiation emitted by the laser bodies of the same row or column. In particular, the guiding laser body does not have a radiation-transmissive aperture on its surface facing away from the common waveguide layer. Apart from the guiding laser body or guiding laser bodies, the other laser bodies can each have a radiation-transmissive aperture on their surfaces facing away from the common waveguide layer.

The laser device can have a plurality of laser bodies forming several rows and columns of laser bodies on the common waveguide layer, wherein at most except for one laser body arranged at the edge or except for the laser bodies arranged at the edge, each of the laser bodies of the same row or same column has a radiation-transmissive aperture facing away from the common waveguide layer. The phase coupling takes place in particular due to the guiding laser body which in particular determines the phase of the emitted radiation/s. It is possible that in this case no stationary wave field is formed in the common waveguide layer.

In all embodiments, active elements configured for controlling or matching refractive index may be integrated or formed in the common waveguide layer. The active elements can be used to control the phase relationship of the individual laser bodies among each other and thus the out-coupling direction in a targeted manner.

According to at least one embodiment, the laser device comprises a first electrode and a second electrode. In particular, the laser bodies are arranged along the vertical direction between the first electrode and the second electrode. In particular, the first electrode and the second electrode are arranged for electrically contacting the laser bodies and/or the common waveguide layer. The first electrode can have a plurality of contact layers, in particular contact layers that can be connected individually, wherein each of which is assigned to one of the laser bodies. The contact layers of the first electrode can each be individually connected to an external voltage source. The second electrode may be formed contiguously and may serve as a common electrode. Alternatively, it is possible for the second electrode to have a plurality of individually connectable contact layers configured to electrically connect the laser bodies and/or to locally electrically connect the common waveguide layer.

The laser device can have a third electrode, which is configured in particular for electrically connecting the common waveguide layer. The second electrode may be arranged in the vertical direction between the first electrode and the third electrode. In particular, the third electrode is formed to be contiguous. The common waveguide layer can be locally selectively electrically connected via the third electrode and the second electrode which in particular has a plurality of laterally spaced contact layers. For example, the third electrode and the second electrode are configured for electrically connecting the active elements integrated or formed in the common waveguide layer.

According to at least one embodiment of the laser device, the first electrode and the third electrode are assigned to a first electrical polarity of the laser device. The second electrode is assigned in particular to a second electrical polarity different from the first electrical polarity. The first electrode and the second electrode are in particular configured for electrically contacting the laser bodies. The second electrode and the third electrode are configured for instance for electrically contacting the common waveguide layer. The second electrode is thus a common electrode that is configured both for electrically contacting the laser bodies and for electrically contacting the common waveguide layer.

According to at least one embodiment of the laser device, the common waveguide layer has at least one side surface which is provided in particular with a radiation non-transmissive layer. The radiation non-transmissive layer may be a radiation-reflecting mirror layer or a radiation-absorbing absorber layer. It is possible that at least two opposite or adjacent side surfaces of the waveguide layer are provided with the radiation-reflecting mirror layer or with the radiation-absorbing absorber layer. Furthermore, it is possible that all side surfaces of the common waveguide layer are provided with the mirror layer or with the absorber layer.

If two opposite side surfaces or all side surfaces of the waveguide layer are provided with mirror layers, a stationary wave field can be formed in the common waveguide layer, which establishes a defined phase coupling of the laser bodies, in particular of all laser bodies of the laser device. If the side surface of the waveguide layer is provided with an absorber layer, no stationary wave field can be formed in the waveguide layer. In this case, phase coupling can be established by a guiding laser body that is mirrored, in particular on the top side, i.e. on the side facing away from the waveguide layer.

A method for producing a laser device, in particular a laser device described herein, is specified. A waveguide layer is provided. A coherent laser body composite may be formed directly on the common waveguide layer. In a subsequent process step, the coherent laser body composite may be structured into a plurality of laterally spaced laser bodies on the common waveguide layer. In this process, a material of the laser body composite can be removed in such a way that intermediate regions are formed which extend through the laser body composite, in particular up to the common waveguide layer or into the waveguide layer.

The laser bodies are formed in particular as local elevations on the common waveguide layer, wherein the laser bodies are enclosed by the intermediate regions in lateral directions. It is possible that the intermediate regions are subsequently filled with an encapsulation material, in particular with an electrically insulating material. For structuring the laser body composite into a plurality of laser bodies, a mechanical process, for example by material removal, or a chemical process, for example an etching process, or a laser separation process can be applied.

The method described herein is particularly suitable for the production of a laser device described herein. The features described in connection with the laser device can therefore also be used for the method, and vice versa.

Identical, equivalent or equivalently acting elements are indicated with the same reference numerals in the figures.

The figures are schematic illustrations and thus not necessarily true to scale. Comparatively small elements and particularly layer thicknesses can rather be illustrated exaggeratedly large for the purpose of better clarification.

Each ofFIGS.1A and1Bshows a structured far field in the form of a diffraction pattern of a one-dimensional and a two-dimensional point lattice, respectively, from a monolithically integrated laser device described here. InFIG.1A, the normalized brightness distribution H as a function of the distribution angle W is schematically shown. InFIG.1Bthe brightness distribution is schematically shown in two dimensions. In particular, with the laser devices shown inFIGS.3A,3B,4and5, the direction of radiation can furthermore be controlled by electrical signals, as a result of which dynamic control of geometric patterns can be achieved.

FIG.2Ashows a laser device10having a plurality of laser bodies2arranged on a common waveguide layer1. In particular, the laser bodies2are formed as local elevations on the common waveguide layer1. In the lateral directions, the laser bodies2are spatially spaced apart from each other by intermediate regions Z. Each of the laser bodies2is formed in an island-like manner and in particular, is fully enclosed by the intermediate regions Z. The intermediate regions Z can be filled with air or with a solid, in particular electrically insulating, material.

The laser bodies2and the common waveguide layer1can be of one-piece or monolithic design. The laser bodies2may each have a sublayer24immediately adjacent to the common waveguide layer1, which has the same material as the common waveguide layer1at least in a transition region between the sublayer24and the waveguide layer1. For example, the sublayers24of the laser bodies2and the common waveguide layer1may be formed from a single piece. In particular, there are smooth transitions between the sublayers24and the common waveguide layer1. For example, there is no clear interface, in particular no clearly detectable interface between the common waveguide layer1and the laser bodies2or between the common waveguide layer1and the sublayers24of the laser bodies2.

The laser bodies2and the common waveguide layer1are further considered to be of one-piece or monolithic design if the laser bodies2are in particular directly applied to the common waveguide layer1. For example, there is no bonding layer, in particular no adhesive layer, glue layer or solder layer, in the vertical direction between the laser bodies2and the waveguide layer1. This is shown schematically, for example, inFIG.2B, wherein the sublayer24associated with a mirror assembly72is formed directly on the waveguide layer1. In this case, the sublayer24and the waveguide layer1may have different material compositions in a common transition region.

Each of the laser bodies2has a semiconductor body2H. In particular, the semiconductor body2H has a first semiconductor layer21of a first charge carrier type, a second semiconductor layer22of a second charge carrier type different from the first charge carrier type, and an active zone23arranged between the semiconductor layers21and22. In operation of the laser device10, the active zone23is particularly configured to generate coherent electromagnetic radiation. In particular, the active zone23is a pn-junction zone. The first semiconductor layer21may be n-conductive. The second semiconductor layer may be p-conductive. However, it is possible that the first semiconductor layer21is p-conductive and the second semiconductor layer22is n-conductive.

The laser bodies2each have a first mirror arrangement71facing away from the waveguide layer1and a second mirror arrangement72facing towards the waveguide layer1. In particular, the first mirror arrangement71and the second mirror arrangement72form a laser resonator7of the laser body2. The mirror arrangements71and72may be Bragg mirrors, in particular electrically conductive Bragg mirrors, or Bragg mirrors made of semiconductor materials. It is possible that the semiconductor body2H, the first mirror arrangement71, the second mirror arrangement72, the sublayer24and/or the waveguide layer1are based on the same semiconductor compound material.

The second mirror arrangement72, which is arranged in the vertical direction between the active zone23and the common waveguide layer1, is in particular formed to be partially transparent to radiation. In particular, the second mirror arrangement72is formed to be at least partially transparent to the radiation S generated in the active zone23during operation of the laser device10, so that the radiation S generated by the active zone23can be coupled through the second mirror arrangement72into the common waveguide layer1. It is possible that the second mirror arrangement72has a lower reflectivity than the first mirror arrangement71. Alternatively or additionally, it is possible that the second mirror arrangement72has a reflectivity for the radiation generated in the active zone23of at most 99%, 95%, 90% or of at most 80%, for instance between 50% and 99% inclusive, or between 60% and 95% inclusive, or between 60% and 80% inclusive.

According toFIG.2A, the laser bodies2each have a radiation passage region6. In particular, the radiation passage region6has an aperture60. The aperture60may be formed by a radiation-transmissive contact layer61. For example, the contact layer61is formed from a transparent electrically conductive material, for instance from a transparent electrically conductive oxide. In particular, the aperture60is fully surrounded in lateral directions by an insulation layer8, in particular by a first insulation layer81. The radiation passage region6is located in particular on a front side10V of the laser device10facing away from the waveguide layer1. Radiation S emitted by the semiconductor body2H can be coupled out of the laser body2through the aperture60. The contact layers61of different laser bodies2are each associated with one of the laser bodies2and can be electrically connected independently from each other. In particular, the contact layers61of the laser bodies2form a first electrode61of the laser device10.

Deviating from this, it is possible that the insulation layer8, in particular the first insulation layer81, is replaced by an electrically conductive layer. In this case, the current can first be impressed over the entire surface of the laser body2and guided to the center by deeper-lying layers. The deeper-lying layers can be oxidized layers in the form of an aperture which narrow the current path from the outside. Alternatively or additionally, the deeper-lying layers can be doped, in particular highly doped current expansion layers located above and/or below the first mirror arrangement71.

According toFIG.2A, the laser device10may include a second electrode62. The second electrode62may be formed as a common electrode for all laser bodies2. In particular, the second electrode62is located on a rear side1R of the common waveguide layer1facing away from the laser bodies2. A front side1V of the waveguide layer1facing the laser bodies2may be free of contact layers. In a top view of the waveguide layer1, the front side1V is covered in regions by the laser bodies2and not covered in regions by the laser bodies2. At the areas not being covered, the front side1V of the waveguide layer1can be freely accessible.

The laser device10has a coupling layer3on the rear side1R of the waveguide layer1. The coupling layer3has a plurality of coupling structures30. In particular, the coupling structures30are local vertical elevations of the coupling layer3that extend into the common waveguide layer1. The coupling structures30may be formed to be radiation reflective. For increasing the reflectivity of the coupling structures30, each of them may be provided with a radiation-reflecting cover layer31. The cover layer31can be formed from a highly reflective material, such as aluminum, silver, palladium or platinum. If the coupling layer3is formed from an electrically conductive material, the coupling layer3can simultaneously serve as a contact layer, in particular as a second electrode62or third electrode63of the laser device10.

Alternatively, it is possible that the cover layer31is not an electrical contact layer. The cover layer31is in particular an optically active layer which couples a part of the horizontally running mode into the laser body2or into the laser bodies2. In particular, the cover layer31and the waveguide layer1have different refractive indices.

In particular, the coupling layer3and/or the second contact layer62and/or the third electrode63directly adjoin/s the waveguide layer1at least in places. In the areas of the coupling structures30, the cover layer31can be arranged in the vertical direction between the waveguide layer1and the associated coupling structure30.

If the cover layer31is formed as an electrical contact layer, an electrical contact resistance between the waveguide layer1and the cover layer31can be lower than an electrical resistance between the waveguide layer1and the coupling layer3. As a result, it can be achieved that charge carriers are preferably impressed via the cover layer31into the waveguide layer1and thus centrally into the laser bodies2. It is possible that the cover layer31is configured for electrically contacting active elements1A, which are integrated or formed in the waveguide layer1, for example.

In top view, each of the laser bodies2may cover, in particular completely cover, at least one coupling structure30. It is possible that in top view, the coupling layer3does not have a coupling structure30that is not covered by one of the laser bodies2. It is also possible that each of the laser bodies2cover a single coupling structure30in top view.

According toFIG.2A, the common waveguide layer1is formed as a single layer. In particular, the common waveguide layer1has the same material composition everywhere. The waveguide layer1is further implemented as a single layer if it is implemented as a layer sequence of several layers that have the same material composition.

According toFIG.2A, the laser device10has a common carrier9. The common waveguide layer1is located in particular in the vertical direction between the common carrier9and the laser bodies2. The common carrier9serves in particular as a mechanically stabilizing carrier layer of the laser device10. The common carrier9can be formed from an electrically insulating or from an electrically conductive material. According toFIG.2A, the laser device10has a rear-side cover layer90arranged on a rear-side surface of the carrier9. The rear-side cover layer90may be formed from an electrically insulating material or from an electrically conductive material. In the presence of the cover layer90, a rear side10R of the laser device is formed by exposed surface of the rear-side cover layer90.

According toFIG.2A, the laser bodies2are arranged to each other in such a way that they are phase-coupled to each other, for instance truly phase-coupled to each other. For example, a lateral distance L between two adjacent laser bodies2is a multiple of the wavelength of the radiation S coupled into the waveguide layer1. A radiation non-transmissive layer4can be arranged on a side surface1S of the waveguide layer or on all side surfaces1S of the waveguide layer. If the radiation non-transmissive layer4is formed to be electrically conductive, an insulation layer may be disposed between the waveguide layer1and the layer4in the lateral direction. The radiation non-transmissive layer4can be a mirror layer41or an absorber layer42. If mirror layers41are arranged on two opposite side surfaces1S of the waveguide layer, a stationary wave field may be formed in the common waveguide layer1. By forming a stationary wave field in the waveguide layer1, phase coupling of the laser bodies2can be established.

Preferably, the coupling structure30is arranged centrally below an associated laser body2. If electromagnetic radiation S is generated in the active zone23, this can be coupled into the waveguide layer1and deflected in lateral directions at the associated coupling structure. The geometry of the coupling structure30may be selected such that the coupled electromagnetic radiation S is deflected in a desired lateral direction. For example, the coupling structure30has the shape of a pyramid or the shape of a cone. According toFIG.2A, the coupling structure30has a lateral cross-section which increases with increasing vertical distance to the associated laser body2.

The exemplary embodiment shown inFIG.2Bis substantially the same as the exemplary embodiment for a laser device10shown inFIG.2A. In contrast,FIG.2Bshows that the common waveguide layer1has an active region13. Furthermore, the common waveguide layer1has a first sublayer11facing the laser bodies2and a second sublayer12facing away from the laser bodies2. In particular, the first sublayer11, the second sublayer12and the active region13of the waveguide layer1are semiconductor layers. The semiconductor layers11,12and/or13may have different material compositions. The coupling structures30extend from the rear side1R of the waveguide layer1into the second sublayer12. In particular, the coupling structures30terminate in front of the active region13.

With the active region13, the common waveguide layer1additionally serves in particular as an optical amplifier. With the active region13and the sublayers11and12, the waveguide layer1has, in particular, a diode structure which, in operation of the laser device10, is configured for generating or amplifying electromagnetic radiation. According toFIG.2B, mirror layers41are arranged on both opposite side surfaces1S of the waveguide layer1. If electromagnetic radiation is coupled from the laser bodies2into the waveguide layer1, it is reflected at the coupling structures or at the cover layers31towards the mirror layers41. The electromagnetic radiations are reflected back at the mirror layers41, as a result of which a stationary wave field is formed in the waveguide layer1, which establishes a well-defined phase coupling of the laser bodies2, in particular of all laser bodies2of the laser device10.

The exemplary embodiment shown inFIG.3Aessentially corresponds to the exemplary embodiment shown inFIG.2B. In contrast, the laser device10has an electrode62arranged on the front side1V, in particular directly on the front side1V, of the waveguide layer1. The electrode arranged on the rear side1R of the waveguide layer1now serves as the third electrode63of the laser device10. In particular, the first electrode61and the third electrode63are assigned to the same electrical polarity of the laser device10. For example, the first electrode61and the third electrode63are configured for p-side contacting of the laser bodies2and/or of the waveguide layer1. The second electrode62is configured for instance for electrically contacting the laser bodies2and the waveguide layer1. Thus, the second electrode62is configured as a common electrode of the laser bodies2and of the waveguide layer1. For example, the second electrode62serves for n-side contacting of the laser bodies2and of the waveguide layer1.

The second electrode62may have a contiguous contact layer62, which is arranged in particular in the free areas Z along lateral directions between the laser bodies2. It is possible for the second electrode62to have a plurality of laterally spaced contact layers62, wherein the contact layers62are formed to be individually contactable. Using the second electrode62, the stationary wave field formed in the waveguide layer1can be electrically amplified. Alternatively or additionally, it is possible that the refractive index, in particular the local refractive index, of the waveguide layer1can be changed by selectively applying an electrical voltage to the second electrode62, which in particular has a plurality of individually contactable contact layers62.

As a further difference toFIG.2B, the laser bodies2each have a lateral passivation layer82or a second insulation layer82. In particular, the second insulation layers82are configured for electrically insulating the contact layers of the second electrode62. The second insulation layer82may differ from the first insulation layer81with respect to its material composition. However, it is possible that the first insulation layer81and the second insulation layer82are formed from the same material. In this case, the insulation layers81and82can be manufactured in a common process.

The exemplary embodiment shown inFIG.3Bessentially corresponds to the exemplary embodiment of a laser device10shown inFIG.3A. In contrast, it is shown schematically inFIG.3Bthat active elements1A are integrated or formed in the waveguide layer1. By integrating the active elements1A, in particular for refractive index controlling or refractive index matching within the waveguide layer1, the phase relationship of the individual laser bodies2to each other and thus the output coupling direction are controllable. The active elements1A may be Wannier-Stark modulators. In particular, the active elements1A serve as phase shifters in the coupling path. For example, the active region13forms at least one quantum well layer or multiple quantum well layers of the active elements1A. In particular, the active elements1A can be individually controlled via the second electrode62which preferably comprises a plurality of individually controllable contact layers62.

In contrast toFIG.3A,FIG.3Bshows mirror layers41applied to the side surfaces1S of the waveguide layer1. Deviating fromFIG.3A, it is possible that radiation non-transmissive layers4, such as mirror layers41or absorber layers42, are arranged on the side surfaces1S.

The exemplary embodiment shown inFIG.4essentially corresponds to the exemplary embodiment for a laser device10shown inFIG.3B. In contrast, the laser device10has at least one guiding laser body2L. The guiding laser body2L does not have a radiation-transmissive aperture60at the front side10V of the laser device10. In particular, the guiding laser body2L is covered, for instance completely covered, by a first contact layer61in top view, which is formed in particular to be opaque to radiation. The electromagnetic radiation S generated in the active zone23of the guiding laser body2L is thus coupled exclusively into the waveguide layer1.

In particular, the coupling layer3has a guiding coupling structure30L, which is covered, in particular completely covered, by the guiding laser body2L in top view. In contrast to the other coupling structures30, the guiding coupling structure30L has a larger vertical height and a larger cross-section. In particular, the guiding coupling structure30L can extend through the second sublayer12and the active region13of the waveguide layer1. Preferably, the guiding coupling structure30L is configured to redirect the coupled radiation S in only one lateral direction, rather than in two opposite lateral directions. For example, the guiding coupler structure30L is not arranged centrally below the guiding laser body2L, but offset with respect to a central axis of the guiding laser body2L, so that the radiation generated by the guiding laser body2L is deflected in one lateral direction in a targeted manner.

In contrast toFIG.3B, the laser device10shown inFIG.4has an absorber layer42on at least one side surface1S or on several side surfaces1S of the waveguide layer1. Electromagnetic radiation is not reflected at the absorber layer42, but absorbed. Thus, no stationary wave field is generated within the waveguide layer1. Instead, the phase coupling is established by the guiding laser body2L which is mirrored on the top side. By integrating the active elements1A, in particular Wannier-Stark modulators, the phase relationship of the individual laser bodies2to each other and thus the out-coupling direction or the radiation direction are controllable.

FIG.5shows a top view of the laser device10. The embodiment shown inFIG.5is substantially the same as the embodiment shown inFIG.4. The waveguide layer1may have a first sub-region1X and a second sub-region1Y. For example, the first sub-region1X extends along a first lateral direction, for instance along the longitudinal lateral direction. The second sub-region1Y extends along a second lateral direction, for instance along the transverse lateral direction. According toFIG.5, the waveguide layer1has a plurality of first sub-regions1X. A plurality of guiding laser bodies2L are arranged on the second sub-region1Y, in particular forming a column of guiding laser bodies2L of the laser device10. On each of the first sub-regions1X, a plurality of laser bodies each having an aperture60are arranged. The absorber layer42is arranged on two adjacent side surfaces1S of the waveguide layer1.

The concept explained in connection withFIG.4is implemented in two dimensions as shown inFIG.5. In particular, the implementation is carried out with two differently controllable sub-regions1X and1Y which are modifiable with respect to the refractive index. Thus, the radiation direction of a diffraction pattern are controllable independently from each other in two lateral directions.

Using a phase-coupled, monolithically integrated and in particular single-mode laser device, the radiation direction or the out-coupling direction of the laser device from a plurality of laser bodies are controllable by electrical signals, as a result of which dynamic control of geometric patterns is achievable. In particular, the laser device is implemented as a single semiconductor chip without optics with optional control of the periodicity of a pattern to be imaged and/or with optional control of its radiation direction by electrical signals without using moving parts, for instance without using moving optical parts.

The invention is not restricted to the exemplary embodiments by the description of the invention made with reference to the exemplary embodiments. The invention rather comprises any novel feature and any combination of features, including in particular any combination of features in the claims, even if this feature or this combination is not itself explicitly indicated in the patent claims or exemplary embodiments.