DE102021103828A1 - SEMICONDUCTOR LASER - Google Patents

Abstract

In one embodiment, the semiconductor laser (1) comprises a semiconductor layer sequence (2) with at least one active zone (21, 22, 23) for generating at least one laser radiation (L1, L2, L3) and perpendicular to a growth direction (G) of the semiconductor layer sequence (2 ) and an electrode (31) on a semiconductor top side (20) of the semiconductor layer sequence (2) for energizing the semiconductor layer sequence (2), wherein the semiconductor layer sequence (2) in a direction transverse to a resonator longitudinal axis (R) and in a plan view of the semiconductor top side (20 ) seen is wider than the electrode (31) and the semiconductor laser (1) can be guided in a gain manner, and- on a deflection surface (4) and/or on a decoupling side (40) for the at least one laser radiation (L1, L2, L3) at least one mode limiter (5) is located, which is set up to limit the at least one laser radiation (L1, L2, L3) in a direction perpendicular to the resonator longitudinal axis (R) when viewed from above on the decoupling side (40). limits.

Description

A semiconductor laser is specified.

The pamphlet US 2013/0016752 A1 relates to a surface emitting laser with multiple active layers.

From the pamphlet U.S. 2009/0097519 A1 lasers with deflection facets are known.

One of the problems to be solved is to specify a semiconductor laser which has a constant radiation characteristic, even across a number of modes.

This object is achieved, inter alia, by a semiconductor laser having the features of the independent patent claim. Preferred developments are the subject matter of the dependent claims.

In accordance with at least one embodiment, the semiconductor laser comprises a semiconductor layer sequence. The semiconductor layer sequence contains one or more active zones for generating at least one laser radiation. The at least one active zone is oriented perpendicular to a growth direction of the semiconductor layer sequence. If several active zones are present, then all active zones can be set up to generate laser radiation with the same spectral properties, or differently configured active zones are present, for example in order to generate laser radiation of different wavelengths.

The semiconductor layer sequence is preferably based on a III-V compound semiconductor material. The semiconductor material is, for example, a nitride compound semiconductor material such as Al _n In _1-nm Ga _m N or a phosphide compound semiconductor material such as Al _n In _1-nm Ga _m P or an arsenide compound semiconductor material such as Al _n In _1-nm Ga _m As or like Al _n Ga _m In _1-nm As _k P _1-k where 0≦n≦1, 0≦m≦1 and n+m≦1 and 0≦k≦1. Optionally, for at least one layer or for all layers of the semiconductor layer sequence, 0<n≦0.8, 0.4≦m<1 and n+m≦0.95 and 0<k≦0.5. In this case, the semiconductor layer sequence can have dopants and additional components. For the sake of simplicity, however, only the essential components of the crystal lattice of the semiconductor layer sequence, ie Al, As, Ga, In, N or P, are specified, even if these can be partially replaced and/or supplemented by small amounts of other substances.

The semiconductor layer sequence is preferably based on the material system Al _n In _1-nm Ga _m As.

In accordance with at least one embodiment, the semiconductor laser comprises an electrode on a semiconductor top side of the semiconductor layer sequence. The electrode is set up for energizing the semiconductor layer sequence. A further electrode can lie opposite the aforementioned electrode, so that at least one of these electrodes is located on each side of the semiconductor layer sequence.

According to at least one embodiment, the semiconductor laser is gain-guided. This means, for example, that the semiconductor layer sequence is wider than the electrode on the semiconductor top side in a direction transverse to a longitudinal axis of the resonator and seen in a top view of the semiconductor top side. In particular, the semiconductor layer sequence has a constant width in a direction perpendicular to a resonator longitudinal axis and along a growth direction of the semiconductor layer sequence. This means that the semiconductor layer sequence can be free of ridges to form a wave guide. Such webs are also referred to as ridges in English. An energization of the semiconductor layer sequence is therefore defined by a shape of the electrode on the top side of the semiconductor and not by a shape of the semiconductor layer sequence itself.

The semiconductor laser described here can therefore be free of a device for optical index guidance of the laser radiation within the semiconductor layer sequence.

According to at least one alternative embodiment, the semiconductor laser is index-guided. This means that the semiconductor laser can have a structuring which brings about a wave guidance of the laser radiation along a resonator. For example, a ridge waveguide is etched into the semiconductor layer sequence.

According to at least one embodiment, at least one mode limiter is located on a deflection surface and/or on a decoupling side for the at least one laser radiation. The mode limiter is set up to cut off the at least one laser radiation in a direction perpendicular to the longitudinal axis of the resonator, as seen in a plan view of the decoupling side. This means that the mode limiter can be used to shape the at least one mode of the at least one laser radiation. In particular, the mode limiter acts also or exclusively along a direction with a smaller divergence angle of the at least one laser radiation, ie in the direction of a so-called slow axis. This direction is in particular oriented parallel to the direction of growth.

In at least one embodiment, the semiconductor laser comprises a semiconductor layer sequence with at least one active zone for generation tion of at least one laser radiation and perpendicular to a growth direction of the semiconductor layer sequence. In addition, the semiconductor laser includes an electrode on a semiconductor top side of the semiconductor layer sequence for energizing the semiconductor layer sequence. The semiconductor laser is gain-guided or index-guided, with the semiconductor layer sequence being wider than the electrode in the direction transverse to a longitudinal axis of the resonator and seen in a top view of the semiconductor top side. At least one mode limiter is located on a deflection surface and/or on a decoupling side for the at least one laser radiation, which mode limiter is set up to limit the at least one laser radiation in a direction perpendicular to the longitudinal axis of the resonator when viewed from above on the decoupling side.

A lateral current widening in broad area laser diodes and superluminescent light emitting diodes, SLEDs for short, cannot be easily controlled and is therefore a design freedom. This topic becomes a problem in particular when a plurality of waveguides are combined, for example in a stacked epi, ie in a semiconductor layer sequence with a plurality of active zones stacked on top of one another. The result is active zones or layers that are not homogeneously energized and thus, in particular, trapezoidal optical near fields of the laser emission.

In the case of semiconductor lasers, the so-called fast axis is generally well defined by the fundamental mode in the waveguide in the epitaxially grown semiconductor layer sequence. In contrast, the so-called slow axis is only specifically influenced by the design, if at all, in the case of single-mode components. The undefined slow axis becomes a problem in particular with multi-mode components, wide-area components and especially with multi-junction lasers or multi-stack lasers.

The semiconductor laser described here is based in particular on the idea of either designing a decoupling facet directly as an aperture or structuring an applied coating as an aperture if the current expansion can only be controlled with great effort. Due to the broken facets and the associated production in the laser bar composite and not at the wafer level, this facet structuring is unfortunately very difficult for edge emitters. For the surface emitter concept, however, this is considerably simpler.

A complex ridge structure can thus be replaced by the mode limiter described here. In the case of gain-guided broad area lasers and broad area SLEDs, primarily surface emitters and also for lasers with several active zones, clearly defined optical near fields are made possible in this way.

In accordance with at least one embodiment, the semiconductor laser includes both the deflection surface and the coupling-out side. In this case, the deflection surface is set up to deflect the at least one laser radiation at one end of the longitudinal axis of the resonator in the direction of the outcoupling side. This means that laser radiation running along the resonator axis towards the deflection surface is reflected towards the outcoupling side. Conversely, laser radiation coming from the decoupling side is preferably deflected back into the resonator by the deflection surface, ie along the longitudinal axis of the resonator.

In accordance with at least one embodiment, the resonator longitudinal axis is oriented perpendicular to the growth direction of the semiconductor layer sequence. The longitudinal axis of the resonator preferably runs as exactly a straight line section, as seen in a plan view of the top side of the semiconductor.

According to at least one embodiment, the deflection surface is oriented transversely to the direction of growth. Alternatively or additionally, the deflection surface is oriented transversely to the longitudinal axis of the resonator. Transverse means in particular an angle of 45° +/- 15° or 45° +/- 5°. This means that the deflection surface can be a 45° mirror. The deflection surface is in particular a flat surface within the manufacturing tolerances. It is possible for the deflection surface to be provided with a reflective coating, in particular with a Bragg mirror. Alternatively, the deflection surface can have a reflective effect due to total reflection.

In accordance with at least one embodiment, the semiconductor laser comprises a plurality of the active zones. The active zones follow one another along the direction of growth. All active zones are preferably aligned perpendicularly to the direction of growth. Each of the active zones may include one or more quantum well layers and intervening barrier layers. That is, at least one or more or all of the active zones can be multi-quantum well structures. A thickness of the active zones is, for example, at least 5 nm and/or at most 1 μm or at most 0.1 μm.

According to at least one embodiment, due to the mode limiter, all laser radiations of all active zones have the same width in the direction of a smaller beam expansion, ie in the direction of the slow axis. This applies in particular with a tolerance of no more than a factor of 1.10 or no more than a factor of 1.05 or no more than a factor of 1.01.

According to at least one embodiment, the mode limiter is set up to a laser threshold outside of an emission range To increase decoupling side, compared to a laser threshold within the emission range. This means that there is a higher laser threshold outside the emission area, so that laser activity in this area is reduced or suppressed relative to the emission area. For example, the quality of a resonator of the semiconductor laser is selectively reduced in places by the mode limiter, that is to say a laser threshold is increased. It is possible for more than one emission area to be present, but there is preferably exactly one emission area.

The emission region is in particular that part of the coupling-out side and/or the top side of the semiconductor which is provided for letting out the at least one laser radiation from the semiconductor laser. In particular, the emission area is a continuous area, for example on a resonator end mirror of the semiconductor laser.

According to at least one embodiment, the coupling-out side is oriented parallel to the growth direction with a tolerance of at most 15° or at most 5°. In particular, these values apply to the emission range, either for each point in the emission range or averaged over the entire emission range. For example, the emission area is a flat surface. Alternatively, the emission area may be a curved surface, for example a lenticular surface.

In accordance with at least one embodiment, the coupling-out side, and thus the emission region, is part of the top side of the semiconductor. This means that the at least one laser radiation can be emitted directly on the top side of the semiconductor or on a decoupling coating directly on the top side of the semiconductor. The decoupling coating can be a dielectric coating and/or a dielectric mirror, with which a reflectivity of the emission area is adjusted.

In accordance with at least one embodiment, the deflection surface is part of a facet of the semiconductor layer sequence. That is to say that the deflection surface is part of a lateral boundary surface of the semiconductor layer sequence. An angle between the deflection surface and the growth direction is, for example, between 30° and 60° inclusive.

In accordance with at least one embodiment, the semiconductor laser comprises at least one deflection optics, which is attached to a facet of the semiconductor layer sequence. For example, the deflection optics is a deflection prism.

According to at least one embodiment, the deflection surface and/or the decoupling side are each a part of an upper side of the deflection optics. The decoupling side is oriented parallel to the top side of the semiconductor, for example. Alternatively, the decoupling side is aligned parallel to the direction of growth.

In accordance with at least one embodiment, the facet of the semiconductor layer sequence that is closest to the deflection surface is oriented perpendicular to the longitudinal axis of the resonator and parallel to the direction of growth, for example with a tolerance of at most 15° or at most 5°. It is possible for the deflection optics and/or the decoupling coating to be attached to this facet.

In accordance with at least one embodiment, the deflection surface is located in a recess in the semiconductor layer sequence. It is possible for the semiconductor layer sequence to be wider than or just as wide as the deflection surface, seen in a top view of the semiconductor top side. For example, the recess is V-shaped in cross-section as viewed parallel to the direction of growth. It is possible for the recess to delimit the semiconductor layer sequence, in particular in the direction parallel to the longitudinal axis of the resonator, or for the semiconductor layer sequence to border the recess all the way around, seen in a top view of the semiconductor top side.

In accordance with at least one embodiment, a width of the deflection surface is equal to a tolerance of at most a factor of 1.2 or at most a factor of 1.1 or at most a factor of 1.05 or at most a factor of 1.01 seen in a top view of the semiconductor top side a width of the electrode. As a result, the width of the recess can define a width of the optical mode of the at least one laser radiation in the semiconductor layer sequence.

In accordance with at least one embodiment, the mode limiter comprises end regions of the semiconductor layer sequence which delimit the cutout. That is to say that the end regions are those regions of the semiconductor layer sequence which delimit the recess along a longitudinal axis of the recess. The longitudinal axis of the recess is preferably oriented perpendicular to the longitudinal axis of the resonator, seen in a plan view of the decoupling side. This means that the end areas can be set up to limit the at least one laser radiation in the direction perpendicular to the longitudinal axis of the resonator. It is possible that the mode limiter consists of these tails.

In accordance with at least one embodiment, the mode limiter comprises or consists of at least one absorption layer. The absorption layer is designed to absorb the at least one laser radiation. The at least one absorption layer preferably surrounds the emission region all around. For example lies an absorption coefficient of the absorption layer for the at least one laser radiation is at least 20% or at least 50% or at least 80% or at least 95%. The absorption layer is made of, for example, a semiconductor material such as Ge or Si, a metal, or a dielectric material such as carbon black.

According to at least one embodiment, the mode limiter comprises or consists of at least one transmission area. The transmission area preferably runs around the emission area in the form of a frame. A transmittance for the at least one laser radiation is greater in the transmission range than in the emission range. For example, a transmission coefficient of the transmission region for the at least one laser radiation is at least 50% or at least 80% or at least 90% or at least 99%. The transmission area is formed, for example, by an antireflection coating that is applied to the outcoupling side around the emission area.

According to at least one embodiment, the mode limiter comprises or consists of at least one light-blocking layer. A transmittance for the at least one laser radiation is lower in an area with the light blocking layer than in the emission area. The light blocking layer is made of a metal, for example. It is possible for the degree of reflection of the light blocking layer for the at least one laser radiation to be at least 50% or at least 80% or at least 90% or at least 98%. In particular, the light-blocking layer has a higher reflectance than the emission region around which the light-blocking layer is arranged.

According to at least one embodiment, the mode limiter comprises a scattering area around the outside of the emission area or consists of a scattering area. The scattering area is preferably set up for diffuse scattering of the at least one laser radiation. For this purpose, the scattering area can include at least one roughening. A structure size of the roughening, also referred to as Ra, is preferably at least 50% or 100% or 200% of a wavelength of maximum intensity of the at least one laser radiation.

In accordance with at least one embodiment, the mode limiter comprises an inner region as seen in a plan view of the outcoupling side. The inner area can be congruent with the emission area. The mode limiter is then preferably shaped like a frame. For example, the interior is rectangular or elliptical, but may also be circular or polygonal.

In accordance with at least one embodiment, the semiconductor laser is set up to generate near-infrared radiation. For example, a wavelength of maximum intensity of the at least one laser radiation is at least 0.7 μm or at least 0.9 μm or at least 1.0 μm. Alternatively or additionally, the wavelength of maximum intensity is at most 3 μm or at most 1.8 μm or at most 1.4 μm.

In accordance with at least one embodiment, the semiconductor layer sequence comprises at least one electrical insulation layer laterally next to the at least one active zone. The at least one electrical insulation layer is set up to prevent a current widening in the semiconductor layer sequence in the direction perpendicular to the longitudinal axis of the resonator. For example, the at least one electrical isolation layer is located between adjacent active zones. This means that with the at least one electrical insulation layer, all active zones can be supplied with current with the same width. The mode limitation can thus include the at least one electrical insulation layer or also consist of it.

All the aspects mentioned above apply equally to superluminescence light-emitting diodes, or SLEDs for short.

A semiconductor laser described here is explained in more detail below with reference to the drawing using exemplary embodiments. The same reference symbols indicate the same elements in the individual figures. However, no references to scale are shown here; on the contrary, individual elements may be shown in an exaggerated size for better understanding.

• 1 und 2 schematische Schnittdarstellungen von Ausführungsbeispielen von hier beschriebenen Halbleiterlasern,
• 3 bis 6 schematische Draufsichten von Ausführungsbeispielen von hier beschriebenen Halbleiterlasern,
• 7 eine schematische Draufsicht auf eine Auskoppelseite für Ausführungsbeispiele von hier beschriebenen Halbleiterlasern,
• 8 eine schematische Draufsicht auf ein Ausführungsbeispiel eines hier beschriebenen Halbleiterlasers,
• 9 und 10 schematische Schnittdarstellungen des Halbleiterlasers der 8,
• 11 bis 13 schematische perspektivische Darstellungen von Ausführungsbeispielen von hier beschriebenen Halbleiterlasern, und
• 14 und 15 schematische Darstellungen eines Emissionsmusters von Ausführungsbeispielen von hier beschriebenen Halbleiterlasern und eines Emissionsmusters eines Lasers ohne Modenbegrenzer.

Show it:

• 1 and 2 schematic sectional representations of exemplary embodiments of semiconductor lasers described here,
• 3 until 6 schematic top views of exemplary embodiments of semiconductor lasers described here,
• 7 a schematic plan view of a coupling-out side for exemplary embodiments of semiconductor lasers described here,
• 8th a schematic plan view of an embodiment of a semiconductor laser described here,
• 9 and 10 schematic sectional views of the semiconductor laser of 8th ,
• 11 until 13 schematic perspective representations of exemplary embodiments of semiconductor lasers described here, and
• 14 and 15 schematic representations of an emission pattern of embodiments of semiconductor lasers described herein and an emission pattern of a laser without mode limiter.

In 1 an exemplary embodiment of a semiconductor laser 1 is shown. The semiconductor laser 1 includes a semiconductor layer sequence 2 which is optionally located on a substrate 29 . The substrate 29 can be a growth substrate of the semiconductor layer sequence 2, or the semiconductor layer sequence 2 was only attached to the substrate 29 after growth. The semiconductor layer sequence 2 is made of AlInGaAs, for example. In order to generate near-infrared laser radiation L1, the semiconductor layer sequence 2 comprises an active zone 21 which is aligned perpendicular to a growth direction G of the semiconductor layer sequence 2. The active zone 21 can extend continuously over the entire semiconductor layer sequence 2 .

The semiconductor layer sequence 2 is energized via an electrode 31 on a semiconductor top side 20 and via a further electrode 32 on the optional substrate 29, so that the semiconductor layer sequence 2 can be located between the electrodes 31, 32.

There is a recess 24 on the semiconductor layer sequence 2, so that a facet 25 is formed. A deflection surface 4 is also formed by the facet 25 . Laser radiation 21 , which runs along a resonator longitudinal axis R towards the deflection surface 4 , is deflected with the deflection surface 4 to a decoupling coating 41 on the top side 20 of the semiconductor. The decoupling coating 41 is, for example, a dielectric coating with which a degree of reflection of the semiconductor top side 20 is set. The laser radiation L1 thus leaves the semiconductor laser 1 in the region of the coupling-out coating 41. The semiconductor top 20 thus simultaneously forms a coupling-out side 40 for the laser radiation L1.

Viewed in cross section, the deflection surface 4 is tilted, for example, 45° with respect to the growth direction G and with respect to the longitudinal axis R of the resonator. The deflection surface 4 can have a totally reflective effect or be provided with a reflective coating, not shown.

The decoupling coating 41 forms a first end of the resonator and an emission region 46 at which the laser radiation L1 leaves the semiconductor laser 1 . A resonator end mirror 62 is located on an opposite side of the resonator and is illuminated via a further deflection surface 61 . The further deflection surface 61 is also preferably tilted 45° with respect to the growth direction G and with respect to the longitudinal axis R of the resonator.

A mode limiter 5 is also located on the coupling-out coating 41. The mode limiter 5 preferably limits the emission region 46 and/or the deflection surface 4.

Exemplary mode limiters 5 are explained in more detail below.

When semiconductor laser 1 of 1 the semiconductor layer sequence 2 is delimited along the resonator longitudinal axis R by the recesses 24 on the deflection surfaces 4, 61, so that a length of the semiconductor layer sequence 2 is defined by the recesses 24. In contrast, according to 2 the semiconductor layer sequence 2 has the recesses 24 along the longitudinal axis R of the resonator.

According to 2 the recesses 24 are designed asymmetrically, so that towards the resonator the deflection surfaces 4, 61 are oriented at an angle of 45°, for example, and facets on the head ends 28 run parallel to the growth direction G. It is just as possible that the recesses 24 are V-shaped and are delimited on both sides by 45° facets, as in 9 illustrated.

In addition, 2 1 illustrates that there can be a plurality of active zones 21, 22, 23, which are arranged stacked on top of one another along the growth direction G. FIG. The active zones 21, 22, 23 are set up to generate laser radiation L1, L2, L3, all of which leave the semiconductor laser 1 at the emission region 46. It is possible that the active zones 21, 22, 23 each reach up to the deflection surfaces 4, 61 or end just before the deflection surfaces 4, 61 in order to avoid damage to the deflection surfaces 4, 61 due to high optical power densities. Optionally, the coupling-out layer 41 and/or the coupling-out side 40 can be not only planar but also structured, for example in the form of a lens. The same applies to all other exemplary embodiments.

In the following, the semiconductor lasers 1 are designed with regard to the recesses 24, as in connection with FIG 2 explained. In all embodiments, however, the design according to 1 present.

In the top view of 3 an exemplary embodiment of the semiconductor laser 1 is shown, with the mode limiter 5 being explained in more detail. The associated recess 24 is on the deflection surface 4 in the direction perpendicular to the growth direction G and perpendicular to the resonator longitudinal axis R approximately as wide as the electrode 31 on the side 20, 40. In the direction parallel to the growth direction G, at least the recess 24 on the deflection surface 4 has a constant, constant width.

A current flow width of the semiconductor layer sequence 2 in the direction perpendicular to the longitudinal axis R of the resonator is defined by the shape of the electrode 32 . This means that laser radiation can essentially only be generated below the electrode 31 in the at least one active zone. In addition, the semiconductor top 20 is planar, so that no waveguide structure is present. In other words, the semiconductor laser 1 according to 3 thus profitable. Alternatively, however, a waveguide structure, such as a ridge waveguide, can also be present, so that an index-guided semiconductor laser 1 can then be present; the same applies to all other exemplary embodiments.

Due to a lateral current conductivity of the semiconductor layer sequence 2, the current widens S in the direction away from the longitudinal axis R of the resonator, symbolized by broad arrows. The extent of the current expansion S usually increases in the direction away from the semiconductor top side 20 . In this way, the active zones 21, 22, 23 that follow one another along the growth direction G are energized with different widths, so that optical modes of different widths would result. The mode limiter 5 prevents this.

A width of the resonator is according to 3 defined by the width of the recess 24. The mode limiter 5 is thus formed by the end regions 51 which delimit the recess 24 and which can be part of the semiconductor layer sequence 2 . Because of these end areas 51, the quality of the resonator is reduced locally. This means that modes of the laser radiation are L1, L2. L3 on the decoupling side 40 in the direction perpendicular to the longitudinal axis R of the resonator all have the same width, so that a uniform emission characteristic can be achieved across all modes in the slow axis direction.

It is possible for the decoupling coating 41 to be applied beyond the recess 24 on the decoupling side 40 . This means that the decoupling coating 41 does not have to exert any mode-limiting influence.

Furthermore, in 3 illustrates that the recess 24 on the further deflection surface 61 can be significantly wider than the electrode 31 and that the resonator end mirror 62 protrudes beyond this recess 24 on all sides. This makes it possible for the coatings 41, 62 to be applied with comparatively small manufacturing tolerances.

Alternatively or additionally, it is possible to make the further deflection surface 61 as wide or approximately as wide as the electrode 31 and/or the recess 24 on the deflection surface 4. The mode limiter 5 can thus include the design of the recess 24 on the further deflection surface 61 or consist of this. This also applies to all other exemplary embodiments.

In the embodiment of 4 the mode limiter 5 is formed by a transmission area 53 around the emission area 46 . In the transmission area 53, a degree of reflection for the laser radiation L1, L2, L3 is, for example, at most 1% or at most 1%. In contrast, there is a degree of reflection of at least 5% or at least 10% in the emission region 46 in order to ensure sufficient amplification of the laser radiation L1, L2, L3 in the resonator. This means that a quality of the resonator around the emission area 46 is reduced by the transmission area 53 .

The transmission region 53 is formed, for example, by a dielectric layer stack made up of alternating SiO ₂ layers and Nb ₂ O ₅ layers. In the emission region 46 there is, for example, an individual layer made of SiO ₂ or Si ₃ N ₄ or else a dielectric layer stack in order to set the desired degree of reflection.

The emission area 46 is rectangular when viewed from above, but can also be circular or elliptical or have another shape. A sharp edge for the laser modes in the slow axis direction is thus defined by the emission region 46, so that all laser modes have the same width.

The mode limiter 5 can deviate from the illustration in 4 also include or consist of such a transmission region 53 on the further deflection surface 61 and/or on the resonator end mirror 62 .

According to 4 the recess 24 on the deflection surface 4 clearly protrudes laterally beyond the electrode 31 . Alternatively, this recess 24 and/or the recess 24 on the further deflection surface 61 can also be designed as in connection with FIG 3 described.

Otherwise, the comments on the 1 until 3 in the same way for 4 .

In the embodiment of 5 the mode limiter 5 is formed by an absorption layer 52 around the emission area 46, so that in turn a quality of the resonator outside of the emission area 46 is reduced. A degree of absorption of the absorption layer 52 for the laser radiation L1, L2, L3 can be almost 100%. For example, the absorption layer 52 includes or is made of Ge.

Otherwise, the statements apply 4 in the same way for 5 . In particular, the mode limiter 5 can alternatively or additionally be attached to the resonator end mirror 62 and/or the end regions 51 to the recesses 24, as in FIG 3 illustrated, include.

According to 6 the mode limiter 5 includes a light-blocking layer 54. For example, the light-blocking layer 54 has a high degree of reflection for the laser radiation L1, L2, L3. For example, the reflectivity of the light blocking layer 54 can be at least 90% or approaching 100%. The light blocking layer 54 is, for example, a metal mirror or a Bragg mirror or a combination of metal mirror and Bragg mirror. Suitable metals are, for example, Au or Ag.

In order to prevent feedback into the resonator being caused at the light-blocking layer 54 , the decoupling side 40 can be structured in the region of the mode limiter 5 and in particular can form or include a scattering layer 55 . For example, a roughening 56 is present in the area of the light blocking layer 54, see FIG 7 . where is in 7 also shown that the emission area 46 can also be designed round, for example circular. The backscattered laser radiation L1, L2, L3 can be reabsorbed in the active zone 21, 22, 23, for example.

Otherwise, the comments on the 4 and 5 in the same way for the 6 and 7 . In particular, the mode limiter 5 can alternatively or additionally be attached to the resonator end mirror 62 and/or the end regions 51 to the recesses 24, as in FIG 3 illustrated, include.

In the 8th until 10 An exemplary embodiment of the semiconductor laser 1 is illustrated in which the mode limiter 5 comprises or consists of at least one electrical insulation layer 27 . The electrical insulation layers 27 extend laterally into the semiconductor layer sequence 2 and are located, for example, between adjacent active zones 21, 22.

The current widening S is prevented by the electrical insulation layers 27, so that the active zones 21, 22 are supplied with current along the growth direction G with a constant width and modes of different widths in the slow axis direction can be prevented. Mode limiters 5 with end areas 51 on the recesses 24, with absorption layers 52, transmission areas 53, light blocking layers 54, scattering areas 55 and/or roughening 56 on the emission area 46 and/or on the resonator end mirror 62 can thus be omitted or additionally present.

The electrical insulation layers 27 are, for example, AlAs layers oxidized at the edges. The electrical insulation layers 27 can reach up to or close to the electrode 31 when viewed from above.

Otherwise, the comments on the 4 until 7 in the same way for the 8th until 10 .

The previous exemplary embodiments are semiconductor lasers 1 with an active zone 21, 22, 23, such as in edge emitters, which have been converted into surface emitters by the deflection surfaces 4, 61, in particular around the absorption layers 52, transmission areas 53, light-blocking layers 54, scattering areas 55 and/or roughening 56 to be able to generate efficiently at the emission region 46 and/or at the resonator end mirror 62 . In contrast, in the 11 and 12 Exemplary embodiments of the semiconductor laser 1 are shown which have facets 25 which are oriented parallel to the growth direction G.

According to 11 the optional decoupling coating 41 is located on one of the facets 25 and the resonator end mirror 62 on an opposite facet 25, which has a degree of reflection of, for example, at least 98% or 99% for the laser radiation L1, L2, L3. A deflection optics 44 is attached to the optional decoupling coating 41 or directly to the associated facet 25 . The deflection optics 44 is a prism, for example.

The decoupling side 40 and the deflection surface 4 are thus located on the deflection optics 44. For example, the decoupling side 40 is oriented parallel to the top side 20 of the semiconductor. The deflection optics 44 can protrude beyond the semiconductor layer sequence 2 in the direction away from the substrate 29 . The mode limiter 5 is located on the decoupling side 40.

According to 12 is the mode limiter 5 directly on the facet 25 or directly on the Auskop fur coating 41 attached. The semiconductor laser 1 is free of deflection surfaces 4, 61.

In 13 1 shows that the semiconductor laser 1 is a vertical cavity surface emitting laser, VCSEL for short. The coupling-out side 40 is thus oriented perpendicularly to the longitudinal axis R of the resonator and to the direction G of growth. The mode limiter 5 is located on the decoupling side 40.

The mode limiters 5 of 11 until 13 are designed in particular, like those associated with the 4 until 7 explained mode limiter 5. That is, the mode limiter 5 of 11 until 13 In particular, the absorption layers 52, transmission areas 53, light blocking layers 54, scattering areas 55 and/or roughening 56 on the emission area 46 and alternatively or additionally on the resonator end mirror 62, or combinations thereof, can include or consist of them. When semiconductor laser 1 of 11 can also have a width of the deflection surface 4 accordingly 3 be designed.

In the 14 and 15 the effect of the mode limiter 5 on the optical modes on the decoupling side 40, ie in the optical near field, is illustrated. So is in 14 to recognize that the, for example, three modes along the Slow Axis direction are all equally wide and have well-defined, sharp edges at the ends. In contrast, the modes end without a mode limiter, see 15 , blurred and can also have different widths.

All of the aspects mentioned above in relation to the semiconductor laser 1 described above apply equally to superluminescence light-emitting diodes, SLEDs for short. That is, instead of a semiconductor laser, there can be an SLED.

The components shown in the figures preferably follow one another in the specified order, in particular directly one after the other, unless otherwise described. Components that are not touching in the figures are preferably at a distance from one another. If lines are drawn parallel to one another, the associated areas are preferably also aligned parallel to one another.

In addition, the relative positions of the drawn components in the figures are correctly represented unless otherwise indicated.

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

Reference List

1

semiconductor laser

2

semiconductor layer sequence

20

semiconductor top

21

first active zone

22

second active zone

23

third active zone

24

recess

25

facet

27

electrical insulation layer

28

headboard

29

substrate

31

electrode

32

further electrode

4

deflection surface

40

decoupling side

41

decoupling coating

44

deflection optics

46

emission range

5

mode limiter

51

the end region delimiting the recess

52

absorption layer

53

transmission range

54

light block layer

55

scatter range

56

roughening

61

further deflection surface

62

resonator end mirror

G

Growth direction of the semiconductor layer sequence

L.

laser radiation

R

longitudinal axis of the resonator

S

current widening

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• US 2013/0016752 A1 [0002]
• US 2009/0097519 A1 [0003]

Claims (15)

Semiconductor laser (1) with - a semiconductor layer sequence (2) with at least one active zone (21, 22, 23) for generating at least one laser radiation (L1, L2, L3) and perpendicular to a growth direction (G) of the semiconductor layer sequence (2), and - An electrode (31) on a semiconductor top (20) of the semiconductor layer sequence (2) for energizing the semiconductor layer sequence (2), wherein - the semiconductor layer sequence (2) is wider than the electrode (31) in a direction transverse to a resonator longitudinal axis (R) and seen in a plan view of the semiconductor top side (20), and - there is at least one mode limiter (5) on a deflection surface (4) and/or on a decoupling side (40) for the at least one laser radiation (L1, L2, L3), which mode limiter is set up to point to the decoupling side (40) in a plan view Seen to limit the at least one laser radiation (L1, L2, L3) in the direction perpendicular to the resonator longitudinal axis (R). Semiconductor laser (1) according to the preceding claim, comprising both the deflection surface (4) and the decoupling side (40), wherein the deflection surface (4) is set up to deflect the at least one laser radiation (L1, L2, L3) at one end of the resonator longitudinal axis (R) in the direction of the decoupling side (40), wherein the resonator longitudinal axis (R) is oriented perpendicularly to the growth direction (G) and the deflection surface (4) is oriented transversely to the growth direction (G) and transversely to the resonator longitudinal axis (R). Semiconductor laser (1) according to one of the preceding claims, comprising several of the active zones (21, 22, 23) which follow one another along the growth direction (G), each of the active zones (21, 22, 23) being set up to generate one of the laser beams (L1, L2, L3), wherein the semiconductor laser (1) is gain-guided. Semiconductor laser (1) according to one of the preceding claims, due to the mode limiter (5), all laser radiation (L1, L2, L3) have the same width in the direction of a smaller beam expansion, with a maximum tolerance of a factor of 1.05. Semiconductor laser (1) according to one of the preceding claims, wherein the decoupling side (40) is oriented parallel to the growth direction (G) with a maximum tolerance of 15° and is part of the semiconductor top side (20), and wherein the deflection surface (4) is part of a facet (25) of the semiconductor layer sequence (2), so that the deflection surface (4) has an angle of between 30° and 60° inclusive to the growth direction (G). Semiconductor laser (1) after Claims 1 until 4 , further comprising deflection optics (44) which are attached to a facet (25) of the semiconductor layer sequence (2), the facet (25) being oriented perpendicular to the resonator longitudinal axis (R) and parallel to the growth direction (G), and the deflection surface (4) and the decoupling side (40) are each part of a top side of the deflection optics (44). Semiconductor laser (1) according to one of Claims 1 until 5 , wherein - the deflection surface (4) is located in a recess (24) of the semiconductor layer sequence (2) and the semiconductor layer sequence (2) is wider than the deflection surface (4) as seen in a top view of the semiconductor top side (20), - in a top view of the Seen from the upper side (20) of the semiconductor, a width of the deflection surface (4) is equal to a width of the electrode (31) with a tolerance of at most a factor of 1.1, and - the mode limiter (5) end regions (51) delimiting the cutout (24). Semiconductor layer sequence (2) comprises, so that the end regions (51) are set up to limit the at least one laser radiation (L1, L2, L3) in the direction perpendicular to the resonator longitudinal axis (R). Semiconductor laser (1) according to one of the preceding claims, in which the mode limiter (5) is set up to increase a laser threshold outside an emission region (46) of the coupling-out side (40) compared to a laser threshold within the emission region (46). Semiconductor laser (1) according to the preceding claim, in which the mode limiter (5) comprises at least one absorption layer (52) which is set up to absorb the at least one laser radiation (L1, L2, L3), the at least one absorption layer (52) den Emission area (46) surrounds all around. Semiconductor laser (1) according to one of the two preceding claims, in which the mode limiter (5) comprises a transmission region (53) around the emission region (46), wherein a transmittance for the at least one laser radiation (L1, L2, L3) is greater in the transmission area (53) than in the emission area (46). Semiconductor laser (1) according to one of the three preceding claims, in which the mode limiter (5) comprises a light-blocking layer (54) on the outside around the emission region (46), a degree of transmission for the at least one laser radiation (L1, L2, L3) being smaller in a region with the light-blocking layer (54) than in the emission area (46). Semiconductor laser (1) according to one of the four preceding claims, in which the mode limiter (5) comprises a scattering region (55) around the outside of the emission region (46), wherein the scattering area (55) is set up for diffuse scattering of the at least one laser radiation (L1, L2, L3) and comprises at least one roughening (56). Semiconductor laser (1) according to one of the preceding claims, in which the mode limiter (5) is in the form of a frame with a rectangular or elliptical inner region, as seen in a top view of the coupling-out side (40). Semiconductor laser (1) according to one of the preceding claims, which is set up for generating near-infrared radiation. Semiconductor laser (1) according to one of the preceding claims, in which the semiconductor layer sequence (2) comprises at least one electrical insulation layer (27) laterally next to the at least one active zone (21, 22, 23), wherein the at least one electrical insulation layer (27) is set up to prevent a current widening in the semiconductor layer sequence (2) in the direction perpendicular to the longitudinal axis (R) of the resonator.

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