Laser arrangement comprising a VCSEL array
A laser arrangement includes a VCSEL array comprising multiple VCSELs arranged on a common semiconductor substrate, an optical structure, and a diffusor structure. The optical structure is arranged to reduce a divergence angle of laser light emitted by each respective VCSEL to a section of the diffusor structure assigned to the respective VCSEL. The diffusor structure is arranged to transform the laser light received from the optical structure to transformed laser light such that a continuous illumination pattern is configured to be provided in a reference plane in a defined field-of-view. The diffusor structure is arranged to increase a size of the illumination pattern in comparison to an untransformed illumination pattern which can be provided without the diffusor structure. The VCSEL array, optical structure, and diffusor structure are arranged such that sections of the diffusor structure do not overlap. Diffusor properties of the diffusor structure vary across the diffusor structure.
1. A laser arrangement comprising:
a VCSEL array comprising multiple VCSELs arranged on a common semiconductor substrate;
an optical structure; and
a diffusor structure,
wherein the optical structure is arranged to reduce a divergence angle of laser light emitted by each respective VCSEL to a section of the diffusor structure assigned to the respective VCSEL,
wherein the diffusor structure is arranged to transform the laser light received from the optical structure to transformed laser light such that a continuous illumination pattern is configured to be provided in a reference plane in a defined field-of-view,
wherein the diffusor structure is arranged to increase a size of the illumination pattern in comparison to an untransformed illumination pattern which can be provided without the diffusor structure,
wherein the VCSEL array, optical structure, and diffusor structure are arranged such that the sections of the diffusor structure assigned to different VCSELs do not overlap,
wherein diffusor properties of the diffusor structure vary across the diffusor structure,
wherein the variation of the diffusor properties is arranged to concentrate the illumination pattern in the defined field-of-view,
wherein the diffusor structure comprises diffusor substructures to vary the diffusor properties which are aligned with the sections receiving the laser light with reduced divergence angle, and
wherein the diffusor substructures are configured with different surface structures to spread laser light received from the optical structure differently depending on the position of the respective VCSEL in the VCSEL array.
2. The laser arrangement according to claim 1 , wherein the optical structure is integrated on wafer level.
3. The laser arrangement according to claim 1 , wherein the optical structure comprises collimating micro lenses configured to reduce the divergence angle by collimating the laser light.
4. The laser arrangement according to claim 3 , wherein the collimating micro lenses are chirped micro lenses.
5. The laser arrangement according to claim 1 , wherein each respective VCSEL is a top emitter arranged to emit the laser light in a direction away from the semiconductor substrate,
wherein the optical structure comprises a material provided on top of a semiconductor layer structure of the VCSEL array, and
wherein the material is transparent in a wavelength range of the laser light.
6. The laser arrangement according to claim 1 , wherein each respective VCSEL is a bottom emitter arranged to emit the laser light through the semiconductor substrate,
wherein the optical structure is provided on a surface of the semiconductor substrate which is arranged opposite with respect to the multiple VCSELs.
7. The laser arrangement according to claim 6 , wherein the optical structure is a collimating optical structure integrated in a semiconductor layer structure of the VCSEL array.
8. The laser arrangement according to claim 6 , wherein the optical structure comprises a material provided on top of a semiconductor layer structure of the VCSEL array, the material being transparent in a wavelength range of the laser light.
9. The laser arrangement according to claim 1 , wherein at least a part of the multiple VCSELs are arranged to be individually controlled to emit laser light.
10. The laser arrangement according to claim 1 , wherein the sections of the diffusor structure are arranged such that each VCSEL is arranged to illuminate a sector of the illumination pattern, wherein each sector overlaps at least with one other sector.
11. The laser arrangement according to claim 1 , wherein the optical structure comprises a partly reflective mirror structure, wherein the partly reflective mirror structure is arranged to decrease the divergence angle of the laser light emitted by each respective VCSEL.
12. A light emitting device comprising:
a laser arrangement array according to claim 1 ; and
an electrical driver for providing an electrical drive current to the multiple VCSELs.
13. A time-of-flight camera comprising:
the light emitting device according to claim 12 , and
a light detector configured to detect transformed laser light reflected by an object,
wherein an evaluator is arranged to determine a distance to the object based on the transformed laser light detected by the light detector.
14. A method of fabricating a laser arrangement, the method comprising:
providing a semiconductor substrate;
providing multiple vertical-cavity surface-emitting lasers (VCSELs) on the semiconductor substrate;
providing an optical structure;
providing a diffusor structure having a plurality of sections; and
arranging the optical structure to reduce a divergence angle of laser light emitted by each respective VCSEL to a respective section of the diffusor structure assigned to the respective VCSEL,
wherein plurality of sections of the diffusor structure are arranged to transform the laser light received from the optical structure to transformed laser light such that a continuous illumination pattern is configured to be provided in a reference plane in a defined field-of-view, and to increase a size of the illumination pattern in comparison to an untransformed illumination pattern which can be provided without the diffusor structure,
wherein the VCSEL array, optical structure, and diffusor structure are arranged such that sections of the diffusor structure assigned to different VCSELs do not overlap,
wherein diffusor properties of the diffusor structure (vary across the diffusor structure,
wherein the variation of the diffusor properties is arranged to concentrate the illumination pattern in the defined field-of-view, and
wherein the diffusor structure comprises diffusor substructures to vary the diffusor properties which are aligned with the sections receiving the laser light with reduced divergence angle, and
wherein the diffusor substructures are configured with different surface structures to spread laser light received from the optical structure differently depending on the position of the respective VCSEL in the VCSEL array.
15. A laser arrangement comprising:
a VCSEL array comprising multiple VCSELs arranged on a common semiconductor substrate;
an optical structure; and
a diffusor structure,
wherein the optical structure is arranged to reduce a divergence angle of laser light emitted by each respective VCSEL to a section of the diffusor structure assigned to the respective VCSEL,
wherein the diffusor structure is arranged to transform the laser light received from the optical structure to transformed laser light such that a continuous illumination pattern is configured to be provided in a reference plane in a defined field-of-view,
wherein the diffusor structure is arranged to increase a size of the illumination pattern in comparison to an untransformed illumination pattern which can be provided without the diffusor structure,
wherein the VCSEL array, optical structure, and diffusor structure are arranged such that the sections of the diffusor structure assigned to different VCSELs do not overlap,
wherein diffusor properties of the diffusor structure vary across the diffusor structure,
wherein the variation of the diffusor properties is arranged to concentrate the illumination pattern in the defined field-of-view, and
wherein the optical structure comprises a partly reflective mirror structure, wherein the partly reflective mirror structure is arranged to decrease the divergence angle of the laser light emitted by each respective VCSEL.
16. The laser arrangement according to claim 15 , wherein the diffusor structure comprises diffusor substructures to vary the diffusor properties which are aligned with the sections receiving the laser light with reduced divergence angle, and
wherein the diffusor substructures are configured with different surface structures to spread laser light received from the optical structure differently depending on the position of the respective VCSEL in the VCSEL array.
17. The laser arrangement according to claim 15 , wherein each respective VCSEL is a top emitter arranged to emit the laser light in a direction away from the semiconductor substrate,
wherein the optical structure comprises a material provided on top of a semiconductor layer structure of the VCSEL array, and
wherein the material is transparent in a wavelength range of the laser light.
18. The laser arrangement according to claim 15 , wherein each respective VCSEL is a bottom emitter arranged to emit the laser light through the semiconductor substrate,
wherein the optical structure is provided on a surface of the semiconductor substrate which is arranged opposite with respect to the multiple VCSELs.
19. The laser arrangement according to claim 18 , wherein the optical structure is a collimating optical structure integrated in a semiconductor layer structure of the VCSEL array.
20. The laser arrangement according to claim 18 , wherein the optical structure comprises a material provided on top of a semiconductor layer structure of the VCSEL array, the material being transparent in a wavelength range of the laser light.