Laser device

Abstract

The invention relates to a VCSEL (10) having a base body (12) which has a resonator (14) for forming a specific laser mode and which has inner Bragg mirrors and an outcoupling mirror adjacent to an outer surface (16) of the base body (12), an active layer for generating light being arranged between the Bragg mirrors, an emission region (20) being arranged on the outer surface (16), the emission region (20) has at least two outcoupling facets (22), which are positioned on the outer surface (16) at positions corresponding to the position of the intensity maximum (19) of the laser mode in order to stabilize the specific laser mode, the outcoupling facets (22) having facet reflectance higher than the surface reflectance of the remaining emission region (20), the facet reflectance of the outcoupling facets (22) being greater than the surface reflectance of the remaining emission region (20), and the facet reflectance of the outcoupling facets (22) being greater than the surface reflectance of the remaining emission region (20). The outcoupling facet (22) does not have a circular outer contour (24).

Description

Technical Field

[0001] The present invention relates to VCSELs for emitting laser light. Summary of the invention

[0002] A VCSEL having a substrate is proposed, wherein the substrate has a resonator for forming a specific laser mode and the resonator has an internal Bragg mirror and a Bragg mirror adjacent to an outer surface of the substrate and serving as a coupling-out mirror, wherein an active layer for generating light is arranged between the Bragg mirrors, wherein an emission region is provided on the outer surface, the emission region having at least two coupling-out facets (Auskoppelfacetten), wherein the at least two coupling-out facets are positioned on the outer surface at positions that coincide with the positions of the intensity maxima of the laser mode, so that the specific laser mode is stable, wherein the coupling-out facets have a facet reflectivity that is higher than the surface reflectivity of the remaining emission region, wherein the coupling-out facets do not have a circular outer contour.

[0003] An emission region is formed on the outer face of the outcoupling mirror, and the outcoupling facets are surrounded by the emission region. The corresponding outcoupling facets are positioned at the positions where the intensity maximum of a particular laser mode is formed. This promotes the particular laser and stabilizes the particular laser mode, because the light at the position of the intensity maximum is reflected into the cavity between the Bragg mirrors, while the light in the region of the remaining emission region is reflected less by comparison.

[0004] Further embodiments and refinements are listed in the dependent claims.

[0005] Advantageously, the outer contour is along the length axis The Bragg mirror has a greater extent than along the width axis, wherein the length axis is oriented perpendicularly to the width axis, wherein the length axis and the width axis are oriented parallel to the outer face. The length axis and the width axis are oriented perpendicularly to the stacking direction of the Bragg mirror. Preferably, the width axis is arranged along the maximum width of the outer contour and the length axis is arranged along the maximum length.

[0006] Preferably, the outer contour is substantially elliptical, rectangular or rhombus-shaped. For example, the width axis is the semi-minor axis of the ellipse and the length axis is the semi-major axis. The same applies to the diagonal of the rhombus shape or the side length of the rectangle, so that the size of the width axis is smaller than the size of the length axis.

[0007] In a specific embodiment, at least two outer contours are shaped differently from one another. At least two outcoupling facets have outer contours that do not have the same shape. This can facilitate a specific pattern.

[0008] Particularly preferably, a facet row with more than two outcoupling facets is arranged along the imaginary line, wherein the outermost outcoupling facets at the respective longitudinal end of the facet row preferably have a different outer contour than the other outcoupling facets in the facet row.

[0009] Advantageously, at least two contour distances along an imaginary line between two directly adjacent outer contours have different sizes, wherein the contour distance is located between directly adjacent intersection points of the respective outer contour with the imaginary line. The contour distance is the distance between the next contour parts of two adjacent outer contours.

[0010] Preferably, the distance between the outer contours that are centrally located with respect to the imaginary line is smaller than the distance between the remaining adjacent outer contours of the same facet row.

[0011] In order to achieve efficient light extraction, two directly adjacent outer contours may be tangential to each other, such that the two outer contours merge into each other.

[0012] In order to achieve polarization of the outcoupling light, a polarization grating can be arranged on at least one outcoupling facet, wherein preferably at least two central outcoupling facets in a facet row have a polarization grating.

[0013] Advantageous further developments can include that in the region of the outer contour, the facet reflectivity of the outcoupling facets is continuously reduced along a reduction section to the level of the surface reflectivity of the remaining emission region, wherein the reduction section has a shortest dimension along which the facet reflectivity is reduced, the shortest dimension preferably being 0.1 micrometer to 3 micrometers. The reduction section can be designed, for example, as a seam-shaped circumferential region around the outcoupling facets. The reduction section can reduce diffraction effects at the edges of the outcoupling facets.

[0014] For example, the length axis may be oriented perpendicular to the imaginary line, while the width axis may be oriented parallel to or on the imaginary line.

[0015] Preferably, an intersection distance is formed between adjacent intersection points of the length axis and the imaginary line, wherein at least two intersection distances are different. Merely as an example, the intersection distance of the central outcoupling facets in the facet row is smaller than the intersection distance in the region of the longitudinal ends of the facet row. This enables an optimal adjustment of the outcoupling facets depending on the laser mode.

[0016] Advantageously, the distance between the intersection points of two adjacent outcoupling facets can be smaller than the extension of one of the adjacent outcoupling facets along the width axis. Thus, the adjacent outcoupling facets overlap and the outer contours of the adjacent outcoupling facets form an intersection point.

[0017] It is particularly preferred that the outer contour of at least one outcoupling facet has straight contour sections. Angular and rounded sections may also be provided.

[0018] The scope of the present invention is limited only by the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be described in more detail below based on exemplary embodiments with reference to the associated drawings. The direction indications in the following description should be understood according to the reading direction of the drawings.

[0020] In the attached picture:

[0021] Figure 1 , Figure 2 and Figures 4 to 7 shows different exemplary embodiments of facet rows,

[0022] Figure 3 A graph with an exemplary laser pattern is shown, and

[0023] Figure 8 The outcoupling facet is shown surrounded by a lowered area. DETAILED DESCRIPTION

[0024] The figure shows a VCSEL 10 (Vertical Cavity Surface Emitting Laser) with a substrate 12. The substrate 12 comprises a resonator 14 formed by two Bragg mirrors, wherein an inner Bragg mirror and an outcoupling mirror are arranged as Bragg mirrors. The outcoupling mirror adjoins an outer face 16 of the substrate 12. In the resonator 14, a specific laser mode 18 is formed, which is fed by light from an active layer arranged between the Bragg mirrors.

[0025] Figure 3 A laser mode 18 is shown in which a plurality of intensity maxima 19 are arranged along an imaginary line 32. The imaginary line 32 represents Figure 3 The x-axis 33 of the diagram in FIG. 35 and the length axis 26 represent the y-axis. The curves in the diagram show the intensity distribution along the axes 33 , 35 .

[0026] The Bragg mirror and the active layer are stacked on top of each other, wherein the stacking direction is oriented perpendicularly to the main extension planes of the layers of the Bragg mirror and the active layer.

[0027] An emission region 20 is provided on the outer face 16, which has at least two outcoupling facets 22. The light of the laser mode 18 is emitted from the outcoupling facets 22. The outcoupling facets 22 are positioned on the outer face 16 at a position that coincides with the position of the intensity maximum 19 of the laser mode 18. The outcoupling facets 22 are arranged on the outer face 16 at a position adjacent to a spatial volume within the resonator 14, which has an antinode of a standing wave under the laser mode 18. Figure 3The corresponding intensity maxima of the exemplary representation in are also located in these spatial volumes.

[0028] The outcoupling facets 22 have a facet reflectivity which is higher than the surface reflectivity of the remaining emission region 20. This leads to a stabilization of the specific laser mode 18, since the corresponding intensity maximum is boosted.

[0029] The outcoupling facet 22 does not have a circular outer contour 24. The outcoupling facet 22 is separated from the remaining emission region 20 by the outer contour 24. The outer contour 24 separates regions with high facet reflectivity from regions with low surface reflectivity.

[0030] exist Figure 1 , the outer contour 24 has a greater extent along a length axis 26 of the respective outcoupling facet 22 than along a width axis 28 of the outcoupling facet 22. The length axis 26 is oriented perpendicularly to the width axis 28 and parallel to the outer face 16 and perpendicularly to the stacking direction.

[0031] Preferably, the width axis 28 is arranged along the maximum width and the length axis 26 is arranged along the maximum length of the outer contour 24. This results in an elliptical outer contour 24. Other shapes such as rectangular or rhombus are also conceivable.

[0032] Figure 3 It is shown that there is a non-circular intensity distribution around the intensity maximum 19. The outcoupling facets 22 and the outer contour 24 are selected accordingly.

[0033] Figure 1 The outcoupling facets 22 are arranged in a facet row 30, wherein there are more than two outcoupling facets 22 along an imaginary line 32. The imaginary line 32 is a straight line. The width axis 28 lies on the imaginary line 32. The imaginary line extends in particular along a common symmetry axis of the outcoupling facets 22.

[0034] because Figure 3 The laser mode 18 in has eight intensity maxima 19, so Figure 1 In the figure, eight outcoupling facets 22 are provided by way of example.

[0035] Figure 2 It is shown that directly adjacent outer contours 24 are tangential to each other, so that these outer contours merge into each other. Therefore, the coupling-out facets 22 overlap each other. The overlapping area of ​​the coupling-out facets 22 is located on the imaginary line 32. Therefore, the coupling-out facets 22 are connected to each other to form a continuous facet row 30.

[0036] exist Figure 4, the corresponding outer contours 24 of the outermost outcoupling facets 221 at the longitudinal ends of the facet row 30 are shaped differently from the outer contours 24 of the outcoupling facets 22 between the outermost outcoupling facets 221. For example, the width axis 281 of the outer contour 241 of the outermost outcoupling facet 221 may be longer than the length axis 261, while the width axis 28 of the outer contours 24 of the remaining outcoupling facets 22 may be shorter than the length axis 26.

[0037] according to Figure 3 , the laser mode 18 has at the outermost intensity maximum 19 an intensity distribution which differs from the remaining intensity distribution of the corresponding intensity maxima 19 which are located between the outermost intensity maxima 191 .

[0038] Preferably, the dimensions of the outcoupling facets 22 in the facet row 30 along the respective longitudinal axis 26, 261 are of equal size. In particular, only the dimensions of the outcoupling facets 22, 221 along the width axis 28, 281 are different. Particularly preferably, the shapes of the outer contours 24 between the outermost outer contours 241 are identical to one another.

[0039] Figure 5 A further embodiment is shown in which the outermost outer contour 241 does not have an elliptical shape. Figure 4 The outermost outer contour 241 in FIG. 3 is the same as that in FIG. 3 , but has a straight contour portion 242 oriented parallel to the imaginary line 32 .

[0040] Figure 6 The following further embodiment is shown, in which the distance 38 between the length axes 26 of adjacent coupling facets 22 has different sizes. In particular, the distance 38 can become smaller towards the center 40, so that the distance 380 between the two longitudinal axes 26 of the central coupling facet 22 is smaller than the distances 381, 382, ​​383 of the remaining coupling facets 22. The distance 38 can gradually increase starting from the center, so that the outermost distance 383 is the largest.

[0041] The distance between the outer contours 22, i.e. the contour distance, can also vary. For example, the contour distance can be measured between two oppositely disposed closest points of adjacent outer contours 24 along the imaginary line 32. The closest point can also be the intersection of the outer contour 22 and the imaginary line 32. As with the distance 38, the contour distance can become larger and larger from the center outward.

[0042] If the distance between the intersection points of two adjacent outcoupling facets 22 is less than the extension of one of the adjacent outcoupling facets 22 along the width axis 28, the outcoupling facets 22 overlap and the outer contours 24 of the adjacent outcoupling facets 22 then intersect with each other. Figure 3The shown are integrated with each other.

[0043] Figure 7 A further embodiment is shown in which the two central outcoupling facets 22 have polarization gratings 42. Alternatively, more than two outcoupling facets 22 may have polarization gratings 42. Further alternatively, only the outer outcoupling facets 22 may have polarization gratings 42 or other dispersed outcoupling facets 22 may have polarization gratings 42.

[0044] Figure 8 An outcoupling facet 22 is shown with a stepped-down section 50 arranged in the region of the outer contour 24. Along the stepped-down section 50, the facet reflectivity decreases continuously to the level of the surface reflectivity of the remaining emission region 20. Figure 8 In the exemplary embodiment of the embodiment of the present invention, the reflectivity decreases along the shortest dimension 52. The dimension 52 of the lowering section 50 is preferably 0.1 micrometer to 3 micrometers. The lowering section 50 is formed in a seam-like manner around the outcoupling facet 22 and extends along the outer contour 24. The dimension 52 can always be constant and is preferably perpendicular to the outer contour 24.

[0045] The features of the embodiments can be combined with each other. Thus, a polarization grating can be used in any of the embodiments. Furthermore, in each embodiment, the distance between the outcoupling facets can be varied. Likewise, the shape of the individual outcoupling facets can be varied accordingly. For example, multiple facet rows can also be created, which are arranged parallel to each other or transversely.

Claims

1. A VCSEL (10) having a substrate (12), the substrate having a resonator (14) for forming a specific laser mode and the resonator having an internal Bragg mirror and an outcoupling mirror adjacent to an outer face (16) of the substrate (12), wherein: An active layer for generating light is arranged between the Bragg mirrors, wherein an emission region (20) is arranged on the outer surface (16), the emission region having at least two outcoupling facets (22), the at least two outcoupling facets being positioned on the outer surface (16) at positions that coincide with the positions of the intensity maximum (19) of the laser mode, so that the specific laser mode is stabilized, wherein the outcoupling facets (22) have a facet reflectivity that is higher than the surface reflectivity of the remaining emission region (20), and wherein the outcoupling facets (22) do not have a circular outer contour (24).

2. The VCSEL (10) according to claim 1, characterized in that The outer profile (24) has a greater extent along a length axis (26) than along a width axis (28), wherein the length axis (26) is oriented perpendicular to the width axis (28), and wherein the length axis (26) and the width axis (28) are oriented parallel to the outer face (16).

3. The VCSEL (10) according to claim 1 or 2, characterized in that: The outer contour (24) is substantially in the shape of an ellipse, a rectangle or a rhombus.

4. The VCSEL (10) according to any one of the preceding claims, characterized in that At least two outer contours (24) are shaped differently compared to one another.

5. The VCSEL (10) according to any one of the preceding claims, characterized in that A facet row (30) having more than two outcoupling facets (22) is arranged along an imaginary line (32), wherein the outermost outcoupling facets (22) at the respective longitudinal ends of the facet row (30) have an outer contour (24) which is preferably different from the remaining outcoupling facets (22) in the facet row (30).

6. The VCSEL (10) according to claim 5, characterized in that At least two contour distances between two directly adjacent outer contours (24) along the imaginary line (32) have different sizes, wherein the contour distances are located between directly adjacent intersection points of the respective outer contours (24) with the imaginary line (32).

7. The VCSEL (10) according to claim 6, characterized in that The distance between the outer contours (24) located in the center with respect to the imaginary line (32) is smaller than the distance between the other adjacent outer contours (24) of the same facet row (30).

8. The VCSEL (10) according to any one of the preceding claims, characterized in that Two directly adjacent outer contours (24) are tangential to each other, so that the two directly adjacent outer contours merge into each other.

9. The VCSEL (10) according to any one of the preceding claims, characterized in that A polarization grating (42) is arranged on at least one outcoupling facet (22), wherein preferably at least two central outcoupling facets (22) of the facet row (30) have a polarization grating (42).

10. The VCSEL (10) according to any one of the preceding claims, characterized in that In the region of the outer contour (24), the facet reflectivity of the outcoupling facet (22) decreases continuously along a reduction section (50) to the level of the surface reflectivity of the remaining emission region (20), wherein the reduction section (50) has a shortest dimension along which the facet reflectivity decreases, and the shortest dimension is preferably 0.1 micrometers to 3 micrometers.

11. The VCSEL (10) according to any of the preceding claims and claims 2 and 5, characterized in that The length axis (26) is perpendicular to the imaginary line (32), while the width axis (28) is parallel to or on the imaginary line (32).

12. The VCSEL (10) according to claim 11, characterized in that Intersection point distances are formed between adjacent intersection points of the length axis (26) and the imaginary line (32), wherein at least two intersection point distances have different magnitudes.

13. The VCSEL (10) according to claim 12, characterized in that The intersection point distance of the central outcoupling facets (22) in the facet row (30) is smaller than the intersection point distance in the region of the longitudinal ends of the facet row (30).

14. The VCSEL (10) according to claim 12 or 13, characterized in that: The distance between the intersection points of two adjacent outcoupling facets (22) is smaller than the extension range of one of the adjacent outcoupling facets (22) along the width axis (28).

15. The VCSEL (10) according to any one of the preceding claims, characterized in that The outer contour (24) of at least one outcoupling facet (22) has a straight contour section (242).

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