Semiconductor component for emitting laser radiation, and array of semiconductor components

Abstract

The invention relates to a semiconductor component for emitting laser radiation, in particular a surface-emitting laser having a vertical cavity (VCSEL), said semiconductor component comprising an optical resonator having a first mirror (14), a second mirror (16) and a pumpable active region (18) between the first mirror (14) and the second mirror (16) for generating laser radiation, wherein the resonator has, on the emission side, an emission region (24) for emitting laser radiation. In at least one dimension perpendicular to the direction of the laser emission, the active region (18) has an extent (L) which is larger by a factor of at least 2 than the extent of the emission region (24) in this dimension. In one or more first sub-regions (26) outside the emission region (24), the resonator has, on the emission side, a first reflectivity which is high enough that a predetermined first laser mode (32) of a higher order is amplified in the resonator, and in one or more second sub-regions (28) outside the emission region (24) the resonator has, on the emission side, a second reflectivity which is low enough, or has an absorption which is high enough, that laser modes other than the first laser mode (32) are suppressed in the resonator. The invention also relates to an array having a plurality of such semiconductor components.

Description

[0001] Semiconductor component for emitting laser radiation and array of semiconductor components

[0002] The invention relates to a semiconductor device for emitting laser radiation, in particular a vertical cavity surface-emitting laser (VCSEL). The invention further relates to an array comprising a plurality of such semiconductor devices.

[0003] From EP 4 131 676 A1, a VCSEL is known whose pumpable active region has an elongated shape, with the longitudinal extent of the active region being many times greater than its lateral extent. Compared to standard VCSELs, such a laser has the advantage that a single higher-order laser mode can be generated and stabilized in the resonator, thereby increasing the laser output power to several tens of milliwatts. In contrast, the output power of a standard VCSEL with a small active region operating in a single fundamental laser mode is limited to a few milliwatts up to 10 milliwatts. The VCSEL known from the aforementioned document emits a plurality of laser beams according to the plurality of intensity peaks of the higher-order laser mode, which is undesirable in some applications of such VCSELs.

[0004] In contrast, WO 2023 / 174717 discloses a VCSEL that also has an extended pumpable active region, wherein the resonator of this VCSEL is configured on the emission side such that laser radiation emerges from an emission region of the resonator that is significantly smaller than the pumpable active region of the VCSEL. This known VCSEL has a resonator that exhibits very high reflectivity, in particular a mirrored surface, throughout the emission side outside the emission region, so that no laser radiation emerges from the resonator from regions outside the emission region.Several higher-order laser modes can form in the resonator, with the laser radiation coupled out from the emission region exhibiting multiple intensity peaks in the near field. This means that the laser radiation in the near field deviates from the Gaussian intensity profile of a standard VCSEL operating in a single fundamental mode, which can also be undesirable. While high output powers can be achieved with this known VCSEL due to its large pumpable active region, the intensity profile of the emitted laser radiation may be undesirable for some applications.The invention is based on the objective of providing a semiconductor device for the emission of laser radiation, in particular a vertical cavity surface-emitting laser (VCSEL), which on the one hand can emit laser radiation with high intensity, and on the other hand is able to emit laser radiation with an intensity profile similar to that of a semiconductor device emitting in a single fundamental mode.

[0005] The invention further aims to provide an array with a plurality of such semiconductor components.

[0006] According to the invention, a semiconductor device for emitting laser radiation is provided, in particular a vertical cavity surface-emitting laser (VCSEL), with an optical resonator comprising a first mirror, a second mirror, and a pumpable active region between the first mirror and the second mirror for generating laser radiation, wherein the resonator has an emission region on the emission side for emitting laser radiation, wherein the active region has an extent in at least one dimension perpendicular to the direction of laser emission that is at least 2 times greater than the extent of the emission region in that dimension, and wherein the resonator has a first reflectivity on the emission side in one or more first subregions outside the emission region that is high enough to amplify a predetermined higher-order first laser mode in the resonator.and in one or more two sub-regions outside the emission region, exhibits a second reflectivity on the emission side that is so low, or an absorption that is so high, that laser modes other than the first laser mode are suppressed in the resonator.

[0007] The semiconductor device according to the invention thus comprises a resonator which, on the emission side (i.e., on the side from which laser radiation is emitted), has at least three regions along the pumpable active region. These regions include the emission region from which laser radiation is emitted, one or more first subregions for amplifying a desired predetermined higher-order laser mode, and second subregions for suppressing laser modes other than the desired laser mode to be emitted. The second subregions can also be referred to as loss regions, i.e., regions in which unwanted laser modes are attenuated by optical losses, either by reduced reflectivity of the resonator in this or these regions or by increased absorption of laser radiation. The second subregions thus prevent unwanted laser modes from propagating in the resonator with significant intensity.The first and second subregions can alternate along the surface of the semiconductor device. The second subregion(s) with reduced reflectivity or increased absorption, combined with a small emission region compared to the active region, ensure that the laser radiation emitted in the emission region can be limited to an intensity peak of the desired higher-order laser mode. This allows the intensity profile of the laser radiation to closely resemble a Gaussian intensity distribution, even in the near field. However, it is also possible for a few intensity peaks of the desired laser mode to be emitted. In this case, the number of emitted intensity peaks is lower, and in particular significantly lower, than the number of intensity peaks of the desired laser mode in the resonator.

[0008] Due to the small number of emitted high-intensity laser beams, or even just one high-intensity laser beam, the semiconductor component according to the invention can be advantageously used for coupling laser light into optical waveguides or optical fibers.

[0009] The desired laser mode is emitted from the first sub-region(s) at a low intensity, if any, wherein the maximum intensity of the laser radiation output in the first sub-region(s) is less than 5%, preferably less than 1%, and even more preferably less than 0.5% of the maximum intensity emitted in the emission region. The maximum intensity of laser radiation emitted in the second sub-region(s) is preferably less than 5%, more preferably less than 1%, and even more preferably less than 0.5% of the maximum intensity emitted in the emission region.

[0010] Advantageous and preferred embodiments of the semiconductor component according to the invention are described below. In a preferred embodiment, the emission region is arranged with at least partial overlap with at least one intensity peak of the first laser mode.

[0011] Preferably, the emission region is arranged with at least partial overlap with exactly one intensity peak of the first laser mode, so that only one intensity peak of the desired laser mode is emitted by the semiconductor device with a Gaussian intensity distribution. This intensity peak is emitted with high intensity due to the significantly larger pumpable active region compared to the emission region. However, it is also possible for the emission region to overlap with several intensity peaks of the first laser mode, allowing the semiconductor device to emit multiple laser beams. The number of intensity peaks of the first laser mode with which the emission region overlaps should be smaller than the total number of intensity peaks of the first laser mode in the resonator.The emission region can have a single emission window that includes several adjacent intensity peaks of the first laser mode, or several emission windows spaced apart along the resonator, for example in the region of the longitudinal ends of the resonator, where each emission window can only be assigned to one intensity peak.

[0012] The overlap of the emission region with at least one intensity peak of the first laser mode can be a complete overlap, i.e., the emission region covers up to 100% of the at least one intensity peak. However, the overlap need not be complete, wherein preferably the intensity of the at least one intensity peak in the emission region is greater than 0.5%, more preferably greater than 5%, and further preferably greater than 13.5% of the maximum intensity of the intensity peak of the first laser mode.

[0013] In a further preferred embodiment, the transmissivity of the resonator in the emission region is greater than 1%, preferably greater than 3%, and more preferably greater than 10%. This ensures that a significant proportion of the first laser mode amplified in the resonator can be emitted from the emission region of the semiconductor component.

[0014] In a further preferred embodiment, the emission-side first reflectivity in the first sub-region(s) is greater than 99.9%, preferably greater than 99.95%, and more preferably greater than 99.99%. In this embodiment, the emission-side first reflectivity of the resonator of the semiconductor component according to the invention in the first sub-region(s) is thus greater than that of standard VCSELs.

[0015] In a further preferred embodiment, the first sub-region(s) are arranged with at least partial overlap to at least one intensity peak of the first laser mode.

[0016] The advantage here is that the desired laser mode can develop in the resonator with high intensity.

[0017] Preferably, each intensity peak of the desired laser mode, with the exception of the intensity peak(s) in the emission regions, is assigned a first sub-region that at least partially overlaps the respective intensity peak.

[0018] Preferably, if the desired laser mode has N intensity peaks, X is the number of emission regions, and M is the number of intensity peaks of the desired laser mode within the emission region(s), then the number Y of first subregions is NM. Furthermore, let Z be the number of second subregions; then Z preferably lies in the range from N - 2M - 1 to N+1. Z = N - 2M - 1 would be the case where no second subregions are present at the outermost edge of the active region, i.e., outside the two outermost intensity peaks, and between the emission region(s) and the first subregions. Z = N+1 would be the case where a second subregion is also present outside the two outermost intensity peaks of the desired laser mode and between the emission region(s) and the first subregions. Furthermore, Y > X, preferably Y > X, and even more preferably Y > 2X.Preferably, in the first sub-region(s), the intensity of the at least one intensity peak is greater than 30%, preferably greater than 13.5%, and more preferably greater than 5% of the maximum intensity of the at least one intensity peak of the first laser mode.

[0019] In a further preferred embodiment, the emission-side second reflectivity of the resonator in the second sub-area or sub-areas is less than 99%, preferably less than 95%.

[0020] By ensuring sufficiently low reflectivity on the emission side of the resonator in the second sub-region(s), unwanted laser modes can be prevented from being amplified in the resonator by coupling out a portion of their intensity. The second sub-region(s) thus effect laser mode discrimination. As mentioned above, it is alternatively or additionally possible to arrange one or more absorption layers in the second sub-region(s), which can also lead to optical losses of the unwanted laser modes.

[0021] Preferably, the second sub-region(s) is / are arranged where the intensity of the first laser mode is less than 30%, preferably less than 13.5%, and more preferably less than 5% of the maximum intensity of the first laser mode. This prevents the desired first laser mode from being attenuated by optical losses.

[0022] If a weighted reflectivity of the emission side of the resonator for a laser mode is defined as (integral of reflectivity of the first sub-region(s) times the intensity of the laser mode within the area of ​​the first sub-region(s) plus integral of reflectivity of the emission sub-region times the intensity of the laser mode within the area of ​​the emission sub-region plus integral of reflectivity of the second sub-region(s) times the intensity of the laser mode within the area of ​​the second sub-region) divided by the integral of the intensity of the laser mode in the entire region, the weighted reflectivity should preferably be similar to or equal to the reflectivity of a standard VCSEL that has the same epitaxial layer structure, the same gain in the active region, the same absorption losses, and the same reflectivity and efficiency of the first and second mirrors.Preferably, the weighted reflectivity should be in the range of 97% to 99.9%, more preferably in the range of 98% to 99.7%, and even more preferably in the range of 99% to 99.6%.

[0023] In a further preferred embodiment, the first or second mirror is an output coupler, wherein the output coupler has a reflectivity of less than 99% in the emission region and in the second subregion(s), wherein the output coupler has a structure in the first subregion(s) that increases the reflectivity.

[0024] The first or second mirror, configured as an output coupler, can thus advantageously be designed like an output coupler of a standard VCSEL. In particular, the output coupler can be composed of semiconductor layer pairs with alternating high and low refractive indices. In the first sub-region(s) that serve to amplify the desired laser mode, the reflectivity is increased by the reflectivity-enhancing structure, preferably to more than 99.9%, as described above in a preferred embodiment.

[0025] In this context, it is further preferred if the structure increasing the reflectivity is a reflective grating, in particular a high-contrast grating, which has a reflectivity of greater than 30%, preferably greater than 50%, and more preferably greater than 70%.

[0026] The reflectivity of the grating is preferably so high that, in combination with the reflectivity of the output coupler, a combined reflectivity of output coupler and reflective grating of at least 99.9% is obtained in the first sub-region(s).

[0027] Furthermore, it is preferred that the reflective grating, in particular the high-contrast grating, has different reflectivities for two mutually perpendicular polarizations, so that the semiconductor device emits more than 90%, preferably more than 99%, of its output power in a single linear position. It is advantageous that not only the desired laser mode can be stabilized in the resonator, but in particular a preferred polarization direction of this laser mode.

[0028] In another preferred embodiment, the output coupler mirror is a distributed Bragg mirror with a plurality of epitaxy layers, wherein the reflectivity-enhancing structure can be incorporated into the outer epitaxy layers.

[0029] Alternatively, according to a further preferred embodiment, a dielectric layer can be arranged on the output coupling mirror, wherein the reflectivity-enhancing structure is incorporated into the dielectric layer.

[0030] Both of the above-mentioned measures have the advantage of a technically simple realization of the semiconductor component according to the invention with emission area, first or first and second or second sub-areas.

[0031] In a further preferred embodiment, the resonator has an anti-reflective coating on the emission side in the emission region. This measure achieves improved emission of the desired intensity peak(s) of the desired laser mode.

[0032] In a further preferred embodiment, the emission region in at least one dimension perpendicular to the direction of laser emission has an extent that is less than 30%, preferably less than 10%, and more preferably less than 5% of the extent of the pumpable active region in that dimension. In other words, the pumpable active region is preferably significantly larger than the emission region.

[0033] In a practical embodiment, the pumpable active region of the semiconductor device has a length greater than 10 pm, preferably greater than 20 pm, and even more preferably greater than 40 pm. The resonator preferably has a current-limiting structure, in particular an oxide blend, which surrounds the pumpable active region.

[0034] The current confinement structure can also be implemented in other configurations as an ion implantation or as a tunnel diode.

[0035] In further embodiments, the pumpable active area can be strip-shaped, ring-shaped, rectangular ring-shaped or cross-shaped.

[0036] In the case of a strip-shaped design, the pumpable active area can be elongated and rectangular, with a width in the range of, for example, 2 - 10 pm and a length in the range of, for example, 10 - 1000 pm.

[0037] In the case of an annular design, wherein the annular ring is preferably closed, the annular ring can have a width in the range of, for example, 2 - 10 pm and a circumferential length in the range of, for example, 10 - 1000 pm.

[0038] In the case of a rectangular pumpable active region, this can have a width in the range of, for example, 2–10 pm and a side length in the range of, for example, 10–1000 pm. Preferably, the corners of the rectangular ring are rounded or have an angle of approximately 45° to reflect the laser mode by 90° from one side of the rectangle to the other.

[0039] A cross-shaped design of the pumpable active area preferably consists of two strips arranged perpendicular to each other.

[0040] Preferably, the semiconductor device is detuned, i.e., the resonator wavelength is preferably larger than the peak wavelength of the gain of the active region to ensure operation of the semiconductor device in higher-order laser modes, with the detuning preferably being greater than that of a standard VCSEL. The active region preferably comprises one or more quantum wells. According to the invention, an array with a plurality of semiconductor devices according to the invention, based on one or more of the aforementioned embodiments, is further provided. Such an array exhibits a low fill factor at high output power of the individual emitted laser beams, which is advantageous for applications of the array with optical elements. Furthermore, each emitted laser beam can advantageously exhibit a Gaussian intensity profile in the near field.

[0041] Possible geometric configurations of the array will be described later with reference to the figures.

[0042] Further advantages and features will become apparent from the following description and the accompanying drawing. It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention.

[0043] Exemplary embodiments of the invention are shown in the drawing and are described in more detail below with reference to them. The drawing shows:

[0044] Fig. 1 schematically shows a semiconductor component for emitting laser radiation according to a first embodiment in a longitudinal section;

[0045] Fig. 2 schematically shows a top view of a surface of the semiconductor component in Fig. 1;

[0046] Fig. 3 schematically shows a semiconductor component for emitting laser radiation according to a further embodiment in a longitudinal section;

[0047] Fig. 4 schematically shows a semiconductor component for emitting laser radiation according to a further embodiment in a longitudinal section; Fig. 5 schematically shows a cross-section, perpendicular to the laser emission, of a pumpable active region of a semiconductor component for emitting laser radiation according to an embodiment;

[0048] Fig. 6 schematically shows a cross-section, perpendicular to the laser emission, of a pumpable active region of a semiconductor component for emitting laser radiation according to a further embodiment;

[0049] Figs. 7A, 7B schematically show a cross-section, perpendicular to the laser emission, of a pumpable active region of a semiconductor component for emitting laser radiation according to a further embodiment;

[0050] Fig. 8 schematically shows a cross-section, perpendicular to the laser emission, of a pumpable active region of a semiconductor component for emitting laser radiation according to a further embodiment;

[0051] Fig. 9 shows the pumpable active area of ​​Fig. 8 with the laser mode indicated;

[0052] Fig. 10 schematically shows a cross-section, perpendicular to the laser emission, of a pumpable active region of a semiconductor component for emitting laser radiation according to a further embodiment;

[0053] Fig. 11 schematically shows a cross-section, perpendicular to the laser emission, of a pumpable active region of a semiconductor component for emitting laser radiation according to a further embodiment;

[0054] Fig. 12 schematically shows cross-sections, perpendicular to the laser emission, of pumpable active regions of semiconductor devices of an array for emitting laser radiation according to one embodiment; Fig. 13 schematically shows cross-sections, perpendicular to the laser emission, of pumpable active regions of semiconductor devices of an array for emitting laser radiation according to another embodiment;

[0055] Fig. 14 schematically shows cross-sections, perpendicular to the laser emission, of pumpable active regions of semiconductor components of an array for emitting laser radiation according to a further embodiment;

[0056] Fig. 15 schematically shows cross-sections, perpendicular to the laser emission, of pumpable active regions of semiconductor components of an array for emitting laser radiation according to a further embodiment;

[0057] Fig. 16 schematically shows cross-sections, perpendicular to the laser emission, of pumpable active regions of semiconductor components of an array for emitting laser radiation according to a further embodiment;

[0058] Fig. 17 schematically shows cross-sections, perpendicular to the laser emission, of pumpable active regions of semiconductor components of an array for emitting laser radiation according to a further embodiment;

[0059] Fig. 18 schematically shows cross-sections, perpendicular to the laser emission, of pumpable active regions of semiconductor devices of an array for emitting laser radiation according to a further embodiment; and

[0060] Fig. 19 schematically shows cross-sections, perpendicular to the laser emission, of pumpable active regions of semiconductor components of an array for emitting laser radiation according to a further embodiment.

[0061] Fig. 1 schematically shows a semiconductor component 10 for emitting laser radiation 12.

[0062] The semiconductor device 10 is, in particular, a vertical cavity surface-emitting laser (VCSEL). The semiconductor device 10 has an optical resonator with a first mirror 14, a second mirror 16, and a pumpable active region 18 for generating laser radiation, wherein the pumpable active region 18 is arranged between the first mirror 14 and the second mirror 16. The electrically pumpable active region 18 is defined by a current confinement structure 19, which can be configured as an oxide aperture. The current confinement structure 19 surrounds the active region 18.

[0063] The first mirror 14 and the second mirror 16 are preferably configured as distributed Bragg mirrors, each comprising a plurality of semiconductor layer pairs 20 and 22, respectively, wherein each semiconductor layer pair 20 and 22 comprises a layer with a high refractive index and a layer with a low refractive index. The pumpable active region 18 preferably comprises one or more quantum wells. Overall, the semiconductor device 10 is composed of semiconductor layers that may be epitaxially grown on a substrate (not shown).

[0064] The resonator has three emission regions along a longitudinal extent L of the pumpable active region 18. These three regions comprise an emission region 24 for the emission of the laser radiation 12 generated in the pumpable active region 18. The emission region 24 has an extent in a dimension perpendicular to the direction of emission of the laser radiation 12, particularly in the direction of the longitudinal extent L, which is less than 50% of the longitudinal extent L of the pumpable active region 18. Preferably, the extent of the emission region 24 is less than 30%, more preferably less than 10%, and more preferably less than 5% of the extent of the pumpable active region 18 in this dimension.

[0065] The three regions of the resonator mentioned above further comprise one or more first subregions 26, which serve to amplify a predetermined desired higher-order first laser mode within the resonator without coupling or emitting this laser mode from the first subregions 26 with significant intensity. The maximum intensity of the coupling of laser radiation of the desired laser mode in the first subregion(s) 26 is less than 5%, preferably less than 1%, and even more preferably less than 0.5% of the maximum emitted intensity in the emission region 24. Furthermore, the three regions of the resonator mentioned above comprise one or more second subregions 28, which serve not to amplify laser modes other than the aforementioned desired first laser mode, but rather to suppress them through losses. The first subregions 26 and the second subregions 28 are distinct from the emission region 24.

[0066] In order to fulfill the aforementioned functions of the emission area 24, the first and the second sub-areas 26, 28, the resonator has a very high reflectivity on the emission side in the first sub-areas 26, while the resonator has a lower reflectivity on the emission side in the second sub-areas 28 and in the emission area 24.

[0067] In the embodiment shown in Fig. 1, the first mirror 14 serves as an output coupler. The first mirror 14 has a reflectivity R < 99% throughout the active region 18. In the emission region 24 and in the second subregions 28, the resonator thus has an emission-side reflectivity R of less than 99%. In the first subregions 26, the first mirror 14 also has a reflectivity R < 99%, but the emission-side reflectivity of the resonator is increased there by a reflectivity-enhancing structure 30. The reflectivity-enhancing structure 30 is preferably an arrangement of high-contrast gratings arranged in the first subregions 26. The reflectivity-enhancing structure 30 has a reflectivity greater than 30%, preferably 50%, and more preferably greater than 70%.In the first sub-areas 26, a combined reflectivity results from the reflectivity of the first mirror 14 and the reflectivity of the reflectivity-enhancing structure 30, where the combined reflectivity R is more than 99.9%.

[0068] In the second sub-regions 28, however, the reflectivity R is < 99%, so that unwanted laser modes are suppressed in the second sub-regions 28 by partial coupling of laser light. The second sub-regions 28 are also referred to as the laser mode discrimination region. In the second sub-regions 26 and in the emission region 24, the emission-side reflectivity of the resonator can be less than 95%. The maximum intensity of laser radiation emitted in the second sub-regions 28 is preferably less than 5%, more preferably less than 1%, and even more preferably less than 0.5% of the maximum emitted intensity in the emission region.

[0069] In a lower sub-image A of Fig. 1, a predetermined desired first laser mode 32 is shown as an example. In this example, the laser mode 32 has seven intensity peaks 34i to 34λ. The emission region 24 is arranged with at least partial, here complete, overlap with the intensity peak 344 of the laser mode 32. The semiconductor device 10 thus emits only the intensity peak 344 in the emission region 24, as a single laser beam, whereby the output power of the laser beam is significantly increased by the amplification of the laser mode 32 in the resonator compared to standard VCSELs, which emit a single fundamental mode. As can be seen from sub-image A in Fig. 1, the extent of the laser mode 32 in the resonator is significantly larger than the emission region 24 of the semiconductor device 10.The emission region 24 should be arranged with respect to the laser mode 32 such that in the emission region 24 the intensity of the at least one intensity peak to be coupled out, here the intensity peak 344, is more than 0.5%, preferably more than 5%, further preferably more than 13.5% of the maximum intensity of the intensity peak of the first laser mode 32.

[0070] Each (further) second sub-region 28 can be located outside the first sub-region 26 shown on the left and right sides of Fig. 1, and / or between the emission region 24 and the respective adjacent first sub-region 26. Generally, preferably: If the desired laser mode has N intensity peaks (in the example of Fig. 1, N = 7), X is the number of emission regions 24 (in the example of Fig. 1, X = 1), and M is the number of intensity peaks of the desired laser mode in the emission region(s) 24 (in the example of Fig. 1, M = 1), then the number Y of first sub-regions 26 is NM (in the example of Fig. 1, Y = 6). If Z is the number of second sub-regions 28, then Z preferably lies in the range from N - 2M - 1 to N + 1. Z = N -2M - 1 would be the case that at the very outer edge along the active region 18, i.e. outside the two outer intensity peaks (in the example of Fig.1 to the left of the intensity peak 34i and to the right of the intensity peak 34?), and no second sub-regions 28 exist between the emission region(s) 24 and the immediately adjacent first sub-regions 26. Z = N + 1 would be the case if a second sub-region 28 exists outside the two outer intensity peaks of the desired laser mode and between the emission region(s) 24 and the immediately adjacent first sub-regions 26. Furthermore, Y > X, preferably Y > X, and even more preferably Y > 2X.

[0071] According to a reflectivity of the output coupler (first mirror 14) of less than 99%, the emission-side transmissivity of the resonator in the emission region 24 is greater than 1%, preferably it can be greater than 3%, and more preferably greater than 10%.

[0072] The first sub-regions 26 are arranged with at least partial overlap with the intensity peaks (in the example, intensity peaks 34i to 34a and 34s to 34?), with the exception of the intensity peak(s) of the first laser mode 32 in the emission region 24 (in the example, intensity peak 344). In the first sub-regions 26, the intensity of the intensity peaks is preferably more than 30%, preferably more than 13.5%, and further preferably more than 5% of the maximum intensity of the respective intensity peak of the first laser mode 32.

[0073] The emission-side reflectivity of the resonator of the semiconductor component 10 is preferably more than 99.9%, preferably more than 99.95%, and further preferably more than 99.99% in the first sub-regions 26. In the second sub-regions 28, however, the reflectivity of the resonator is, as already mentioned, less than 99%, preferably less than 95%.

[0074] In the second sub-regions 28, the intensity of the first laser mode 32 is less than 30%, preferably less than 13.5%, and further preferably less than 5% of the maximum intensity of the first laser mode 32. The lower the intensity of the intensity peaks 34i to 34? of the desired laser mode 32 in the lossy second sub-regions 28, the less intensity of the first laser mode 32 is lost.

[0075] Fig. 2 shows a top view of the semiconductor device 10, where the reflective lattice structure 30 is indicated by lattice lines arranged over the intensity peaks 34i to 34a and 34s to 34λ. The emission region 24 is also illustrated in Fig. 2, as is the intensity peak 344 emitted from the emission region 24. Between the lattice structures 30 of the first subregions 26 are the second subregions 28, which serve to attenuate unwanted laser modes by partially coupling them out. As shown in Fig. 2, the intensity of the desired laser mode 32 is low in the second subregions 28.

[0076] In the second sub-regions 28, an absorbing layer can be arranged on the first mirror 14 to increase the losses in the second sub-regions 28 due to absorption and to prevent transmission of laser radiation of the desired laser mode or spontaneous emission from the amplifying layer outside the emission region 24. An absorbing layer can also be arranged on the grating structure 30 in the first sub-regions 26.

[0077] A weighted reflectivity of the first mirror 14 serving as an output coupler for the desired laser mode is defined as the integral of the reflectivity of the first sub-regions 26 multiplied by the intensity of the laser mode within the area of ​​the first sub-regions 26, plus the integral of the reflectivity of the emission region 24 multiplied by the intensity of the laser mode within the area of ​​the emission region 24, plus the integral of the reflectivity of the second sub-regions 26 multiplied by the intensity of the laser mode within the area of ​​the second sub-regions 26, wherein the aforementioned sum is divided by the integral of the intensity of the laser mode in the entire region.The weighted reflectivity of the output coupler 14 can preferably be similar to or equal to the weighted reflectivity of a standard VCSEL with the same epitaxial layer structure (same quantum well gain, same absorption losses, same mirror reflectivity and efficiency). The weighted reflectivity for all other laser modes, which is calculated analogously to the above-described calculation of the weighted reflectivity of the desired laser mode using the intensity profile of the respective other laser mode, is preferably smaller than the weighted reflectivity of the desired laser mode.

[0078] The pumped active region 18 can have a long dimension L greater than 10 pm, preferably greater than 20 pm, and more preferably greater than 40 pm. Various geometries of the pumpable active region 18 are described below. The different reflectivities in the at least three regions (emission region 24, first subregions 26, second subregions 28) of the first mirror 14 can be realized in various ways.

[0079] Fig. 3 shows an embodiment in which, after the epitaxial growth of the first mirror 14 with low reflectivity, the lattice structure 30 is incorporated into the upper epitaxial layer 40 in the sub-regions 26. The upper layer 40 can be a GaAs layer with an interface to air. Optionally, a passivation layer, for example a SiN layer, can be applied to the upper layer 40.

[0080] According to Fig. 4, a dielectric layer 42 can be applied to the first mirror 14, into which the grid structure 30 is incorporated in the first sub-areas 26.

[0081] In both the embodiment shown in Fig. 3 and the embodiment shown in Fig. 4, an anti-reflective coating can optionally be applied to the emission area 34. Furthermore, an absorbing layer can optionally be applied to the second sub-areas 28 and / or to the first sub-areas 26.

[0082] Preferably, the reflective grating 30, particularly in the form of a high-contrast grating, has significantly different reflectivities for two mutually perpendicular polarization directions in order to stabilize the emitted laser radiation 12 in one of the polarization directions and to suppress the other polarization direction. Preferably, the semiconductor device 10 emits more than 90%, and preferably more than 99%, of its output power in the stabilized polarization direction.

[0083] With reference to Figures 5 to 11, various possible geometries of the pumpable active area are described below as examples.

[0084] In schematic Figures 5 to 11, only the pumpable active region 18, the emission region 24, the first subregions 26 represented by the lattice structure 30, and the second subregions 28 between the lattice structures are shown. Figure 5 shows an embodiment of the pumpable active region 18 in the form of an elongated straight strip. The strip can also be curved in the longitudinal direction. The width B of the strip can be in the range of 2–10 pm, and its length L in the range of 10–1000 pm. The embodiment according to Figure 5 has an emission region 24 that is arranged centrally along the length L of the pumpable active region 18 and emits only an intensity peak of the desired first laser mode. However, the emission region can also be arranged off-center.

[0085] Fig. 6 shows an annular embodiment of the pumpable active area 18. The width B of the annular pumpable active area 18 can be in the range of 2–10 pm and the circumferential length in the range of 10–1000 pm. In the embodiment according to Fig. 6, the lattice structure 30 in the first sub-areas is oriented radially with respect to the center of the annular active area 18.

[0086] Fig. 7A shows a rectangular annular configuration of the pumpable active area 18, with the corners of the rectangle being rounded. The corners can also be straight and arranged at an angle of 45° to the sides of the rectangle, as shown in Fig. 7B. The width B of the active area 18 can be in the range of 2–10 pm, and the side length L can be in the range of 10–1000 pm.

[0087] While in the previous embodiments the emission region 24 emits only one intensity peak of the laser mode 32, in Figs. 8 to 11 embodiments are shown in which the emission region 24 emits more than one intensity peak of the desired laser mode 32.

[0088] In Figures 8 and 9, the emission region 24 overlaps with four intensity peaks 34. The first subregions 26 with the lattice structure 30 overlap with the remaining intensity peaks of the laser mode 32. In the embodiment according to Figures 8 and 9, the semiconductor component 10 thus emits four intensity peaks of the laser mode 32.

[0089] Fig. 10 shows an embodiment in which the emission region 24 emits two non-adjacent intensity peaks of the laser mode 32. While Figs. 8 to 10 show the extraction of several intensity peaks for a strip-shaped, straight-line pumpable active region 18, Fig. 11 shows the extraction of several intensity peaks, here exactly two diametrically opposed intensity peaks, for an annular configuration of the active region 18.

[0090] With reference to Figures 12 to 19, exemplary geometries of arrays 50 are described below, which have a plurality of semiconductor devices 10 according to one or more of the previously described embodiments. Figures 12 to 19 show only the pumpable active regions 18 and the emission regions 24 of the arrays 50.

[0091] Fig. 12 shows an array in which the active regions 18 of the respective semiconductor devices correspond to the active region 18 according to Fig. 5. In the embodiment shown in Fig.

[0092] 12 the strip-shaped active areas 18 are arranged parallel to each other without lateral offset.

[0093] The array 50 in Fig. 13 has a plurality of semiconductor components whose active regions 18 and emission regions 24 are arranged parallel to each other, but offset from row to row by half the length of the respective active region 18.

[0094] The array 50 according to Fig. 14 has a plurality of semiconductor components, wherein active areas 18 of adjacent semiconductor components are arranged perpendicular to each other.

[0095] In the array 50 shown in Fig. 15, the active regions 18 of the semiconductor devices are configured as crossed stripes, with the respective emission region 24 located in the center of each cross-shaped active region 18. The individual pumpable active regions 18 are arranged interlocked.

[0096] The array 50 in Fig. 16 corresponds to the array 50 in Fig. 15, except that some of the individual pumpable active regions 18 are arranged rotated by 45° relative to the active regions 18 of the other semiconductor devices. The array 50 in Fig. 17 has a single, contiguous, large pumpable active region 18, which is lattice-shaped, with the emission regions 24 arranged at lattice intersection points of the active region.

[0097] Fig. 18 shows an array 50 comprising semiconductor components with a respective active region 18, corresponding to the embodiment in Fig. 11, wherein, in contrast to Fig. 11, the emission region 24 emits four intensity peaks of the desired laser mode.

[0098] Fig. 19 shows a modification of the array 50 of Fig. 18, in which several annular pumpable active areas 18 are combined into a single large pumpable active area 18.

[0099] The embodiments according to Figs. 12 to 19 have in common that the respective array 50 has a high output power per individual laser beam emitted from the emission area 24 with a low fill factor of the emitted laser beams.

Claims

Patent claims 1. Semiconductor component for emitting laser radiation, in particular a vertical cavity surface-emitting laser (VCSEL), comprising an optical resonator with a first mirror (14), a second mirror (16) and a pumpable active region (18) between the first mirror (14) and the second mirror (16) for generating laser radiation, wherein the resonator has an emission region (24) on the emission side for emitting laser radiation, wherein the active region (18) has an extent (L) in at least one dimension perpendicular to the direction of laser emission which is greater by a factor of at least 2 than an extent of the emission region (24) in this dimension, characterized in that the resonator has a first reflectivity on the emission side in one or more first subregions (26) outside the emission region (24) which is such that a predetermined first higher-order laser mode (32) is amplified in the resonator.and in one or more second sub-regions (28) outside the emission region (24) has a second reflectivity on the emission side that is so low, or an absorption that is so high, that laser modes other than the first laser mode (32) are suppressed in the resonator.

2. Semiconductor component according to claim 1, wherein the emission region (24) is arranged with at least partial overlap to at least one intensity peak (344) of the first laser mode (32).

3. Semiconductor component according to claim 2, wherein in the emission region (24) the intensity of the at least one intensity peak (344) is greater than 0.5%, preferably greater than 5%, further preferably greater than 13.5% of the maximum intensity of the at least one intensity peak (344) of the first laser mode (32).

4. Semiconductor component according to one of claims 1 to 3, wherein the transmissivity of the resonator in the emission region (24) is greater than 1%, preferably greater than 3%, further preferably greater than 10%.

5. Semiconductor component according to one of claims 1 to 4, wherein the first reflectivity in the first sub-region(s) (26) is greater than 99.9%, preferably greater than 99.95%, further preferably greater than 99.99%.

6. Semiconductor component according to one of claims 1 to 5, wherein the first sub-region(s) (26) are arranged with at least partial overlap to at least one intensity peak (34i, 342, 34a, 34s, 34e, 34?) of the first laser mode (32), preferably wherein in the first sub-region(s) (26) the intensity of the at least one intensity peak (34i, 342, 34a, 34s, 34e, 34?) is greater than 30%, preferably greater than 13.5%, further preferably greater than 5% of the maximum intensity of the at least one intensity peak (34i, 342, 34a, 34s, 34e, 34?) of the first laser mode (32).

7. Semiconductor component according to any one of claims 1 to 6, wherein the second reflectivity in the second sub-region(s) (28) is less than 99%, preferably less than 95%.

8. Semiconductor component according to one of claims 1 to 7, wherein in the second sub-region(s) (28) the intensity of the first laser mode (32) is less than 30%, preferably less than 13.5%, more preferably less than 5% of the maximum intensity of the first laser mode (32).

9. Semiconductor component according to one of claims 1 to 8, wherein the first or the second mirror (14, 16) is an output coupling mirror, wherein the output coupling mirror has a reflectivity of less than 99% in the emission region (24) and in the second sub-region(s) (28), wherein the output coupling mirror has a reflectivity-enhancing structure (30) in the first sub-region(s) (26).

10. Semiconductor component according to claim 9, wherein the reflectivity-enhancing structure (30) is a reflective grating, in particular a high-contrast grating, with a The reflectivity is greater than 30%, preferably greater than 50%, and more preferably greater than 70%.

11. Semiconductor device according to claim 10, wherein the reflective grid has different reflectivities for two mutually perpendicular polarizations, such that the semiconductor device (10) emits more than 90%, preferably more than 99% of its output power in a single linear polarization.

12. Semiconductor component according to one of claims 9 to 11, wherein the output coupling mirror is a Bragg mirror with a plurality of epitaxy layers, and wherein the reflectivity-enhancing structure (30) is incorporated into the outer epitaxy layer(s) (40).

13. Semiconductor component according to one of claims 9 to 11, wherein a dielectric layer (42) is arranged on the output coupling mirror, and wherein the reflectivity-enhancing structure (30) is incorporated into the dielectric layer (42).

14. Semiconductor component according to one of claims 1 to 13, wherein the resonator has an anti-reflective coating on the emission side in the emission region (24).

15. Semiconductor component according to one of claims 1 to 14, wherein the emission region (24) in the at least one dimension perpendicular to the direction of laser emission has an extent which is less than 30%, preferably less than 10%, further preferably less than 5% of the extent (L) of the pumpable active region (18) in this dimension.

16. Semiconductor component according to any one of claims 1 to 15, wherein the resonator has a current confinement structure (19), in particular an oxide blend, which defines the pumpable active region (18).

17. Semiconductor component according to one of claims 1 to 16, wherein the pumpable active area (18) is strip-shaped or annular or rectangular or cross-shaped.

18. Array comprising a plurality of semiconductor devices (10) according to any one of claims 1 to 17.

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