LASER DEVICE INCLUDING A SCREENING ELEMENT

Abstract

The invention relates to a laser device which includes at least one laser diode having an emission surface via which the laser diode can emit laser light during operation, and a screening element having an entry surface facing the emission surface.

Claims

1. A laser apparatus comprising at least one laser diode having an emission surface via which the laser diode can emit laser light during operation, and a screening element having an entrance surface which faces the emission surface, wherein the emission surface of the laser diode is arranged in a non-hermetically sealed environment and the screening element is arranged such that an optical tweezers effect caused by the laser light at the emission surface is prevented entirely or at least partially.

2. A laser apparatus comprising at least one laser diode having an emission surface via which the laser diode can emit laser light during operation, and a screening element having an entrance surface which faces the emission surface, wherein the laser light emitted during operation has a beam waist that is located in a gap between the emission surface and the entrance surface.

3. The laser apparatus as claimed in claim 1, wherein the entrance surface of the screening element has a distance from the emission surface of the at least one laser diode that is smaller than or equal to 3μm.

4. The laser apparatus as claimed in claim 1, wherein the entrance surface of the screening element has a distance from the emission surface of the at least one laser diode that is greater than 0.

5. The laser apparatus as claimed in claim 1, wherein the screening element does not adhere to the emission surface.

6. The laser apparatus as claimed in claim 1, wherein the screening element is transparent to the laser light.

7. The laser apparatus as claimed in claim 1, wherein the entrance surface (21) of the screening element (2) has a distance from the emission surface (11) of the at least one laser diode that is smaller than or equal to 10 μm.

8. The laser apparatus as claimed in claim 1, wherein the emission surface adjoins air.

9. The laser apparatus as claimed in claim 2, wherein the entrance surface of the screening element has a distance from the emission surface of the at least one laser diode that is smaller than or equal to 3 μm.

10. The laser apparatus as claimed in claim 2, wherein the entrance surface of the screening element has a distance from the emission surface of the at least one laser diode that is greater than 0.

11. The laser apparatus as claimed in claim 2, wherein the screening element does not adhere to the emission surface.

12. The laser apparatus as claimed in claim 2, wherein the screening element is transparent to the laser light.

13. The laser apparatus as claimed in claim 2, wherein the entrance surface (21) of the screening element (2) has a distance from the emission surface (11) of the at least one laser diode that is smaller than or equal to 10 μm.

14. The laser apparatus as claimed in claim 2, wherein the emission surface adjoins air.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Further advantages, advantageous embodiments and developments arise from the exemplary embodiments described below in conjunction with the figures.

[0028] In the figures:

[0029] FIGS. 1A and 1B show schematic illustrations of a laser apparatus according to one exemplary embodiment, and

[0030] FIG. 2 shows a schematic illustration of a comparative example of a laser.

DETAILED DESCRIPTION

[0031] In the exemplary embodiments and figures, elements that are the same, are of the same type, or act in the same way can be provided in each case with the same reference signs. The elements illustrated and their mutual size ratios should not be considered to be true to scale, but rather it is possible that individual elements, for example layers, components, structural components and regions, are depicted with an exaggerated size for the purpose of enabling easier illustration and/or better comprehension.

[0032] FIGS. 1A and 1B show a top view and a side view of a laser apparatus 100 according to one exemplary embodiment.

[0033] The laser apparatus 100 comprises at least one laser diode 1. The laser diode 1 is provided and set up to emit during operation light that is laser light 10 at least when specific threshold conditions are exceeded. The laser diode 1 can in particular be designed as is described in the general part. The laser diode 1 shown in FIGS. 1A and 1B is designed in particular as an edge-emitting semiconductor laser. Alternatively, the laser diode 1 can also be designed as a VCSEL. The following description in this case applies accordingly.

[0034] Furthermore, the laser apparatus 100 can comprise a plurality of laser diodes. Even where the following description refers to only one laser diode 1, the corresponding features also apply to a plurality of laser diodes.

[0035] Furthermore, the laser apparatus 100 comprises a screening element 2, which is arranged downstream of the laser diode 10 in the emission direction of the laser light 10.

[0036] The laser diode 1 and the screening element 2 can be arranged and mounted, as is indicated in FIG. 1B, for example on a carrier 8. In particular, the laser diode 1 and the screening element 2 can be pre-manufactured components that are mounted on the carrier 8. In particular, the screening element 2 is designed not as potting or as a similar element which is only producible on the carrier 8 using a molding process.

[0037] As is indicated in FIGS. 1A and 1B, the laser diode 1 can be mounted on the carrier 8 with what is known as a submount 9, which can be made with or from AIN or another material with good thermal conductivity and can be set up for dissipating operating heat from the laser diode 1.

[0038] The laser diode 1 has an emission surface 11 on a coupling-out side, from which the laser light 10 generated during operation can exit the laser diode 1. The emission surface 11 forms an interface of the laser diode 1 with which the laser diode 1 adjoins the surrounding medium, which is not an integral part of the laser diode 1. The emission surface 11 can be formed, for example, by a surface of the semiconductor layer sequence of the laser diode 1 or by a surface of a coating on the semiconductor layer sequence. The surrounding medium that adjoins the emission surface 11 can with particular preference be air. With particular preference, the laser diode 1 is arranged in a non-hermetically sealed environment. In particular, the laser diode 1, with particular preference the emission surface 11, can be in direct contact with an atmosphere surrounding the laser apparatus 100 and consequently in direct contact with air.

[0039] The screening element 2 comprises or consists of a material that is transparent to the laser light 10. For visible laser radiation, the screening element 2 can comprise or consist of, for example, glass, sapphire or diamond, or a plastic described in the general part. For laser light 10 in the infrared range, for example, the screening element 2 can comprise or consist of silicon. The screening element 2 has an entrance surface 21, which faces the emission surface 11 and through which the laser light 10 enters the screening element 2. The screening element 2 furthermore has an exit surface 22, through which the laser light 10 exits the screening element 2.

[0040] The screening element 2 can be designed, as shown, as a plate or a block and preferably have no intended optical effects on the laser light 10. Alternatively, the screening element 2 can make beam deflection possible, for example, and be designed as a prism, for example, in which the entrance surface 21 and the exit surface 22 are not located one behind the other along the original beam direction of the laser diode 1, in contrast to the case of a plate or a block. Furthermore, at least one or both of the entrance and exit surfaces of the screening element can have an at least partially curved shape.

[0041] As is described in the general part, the beam divergence of the laser light 10 indicated in FIG. 1A brings about, in conjunction with the energy density of the laser light 10, an optical tweezers effect. FIG. 2 shows a comparative example of a laser diode 1, which does not have a screening element arranged downstream of it and in which particles 99, indicated by way of example by the optical tweezers effect, are transported from the environment in the direction of the emission surface 11. The material deposition on the emission surface 11 that is caused thereby can lead to diminished output power and to damage that can lead to a total failure of the laser.

[0042] The laser apparatus 100 according to the exemplary embodiment of FIGS. 1A and 1B comprises an arrangement through which the optical tweezers effect is prevented entirely or at least partially. The arrangement and the design of the screening element 2 is particularly preferably such that the divergent laser light beam is guided in the screening element 2 and thus in a medium in which the forces required for the material transport are higher than the forces built up in the laser light field, as a result of which the material transport to the emission surface 11 of the laser diode 1, which has been caused by the optical tweezers effect, can preferably come to a standstill. An accumulation of deposits on the emission surface 11 can be suppressed thereby. Depending on the laser beam characteristic, the path of the laser light in the screening element 2 can thus be set by suitably dimensioning the screening element and in particular by a suitable distance of the entrance surface 21 from the exit surface 22. With the lower irradiance on the light exit side of the screening element 2, that is to say on the side of the exit surface 22, a ratio between absorption and desorption can be achieved that no longer leads to accumulation of particles or molecules. Even if tweezer effects should still occur, as is indicated in FIG. 1A purely by way of example using the particle 99, they are with particular preference considerably less critical at the light exit surface of the screening element 2 than at the emission surface 11.

[0043] The distance D between the emission surface 11 and the entrance surface 21, and thus the width of the gap 3 between the emission surface 11 and the entrance surface 21, is preferably less than or equal to 10 μm and with particular preference less than or equal to 3 μm. Furthermore, the distance D can be greater than 0. As is indicated in FIG. 1A, the typically occurring beam waist can be located in the gap 3 between the emission surface 11 and the entrance surface 21, since in the region thereof there may be a high energy density but no, or only a low, divergence.

[0044] A hermetic package free of organic materials for the laser diode 1 is no longer needed in the laser apparatus 100 described here. A hermetic package can be replaced by a considerably simplified arrangement that can in particular protect the at least one laser diode 1 and the arrangement as a whole against mechanical damage and environmental influences. This means costs can be lowered and the space required for the laser apparatus 100 can be significantly smaller compared to conventional laser packages. Moreover, the laser functionality can be more easily and better integrated in applications and modules, which is a considerable advantage given the general trend toward miniaturization.

[0045] The features and exemplary embodiments described in conjunction with the figures can, according to further exemplary embodiments, be combined with one another, even if not all combinations have been explicitly described. Furthermore, the exemplary embodiments described in conjunction with the figures may additionally or alternatively have further features in accordance with the description in the general part.

[0046] The invention is not restricted to the exemplary embodiments by the description on the basis thereof. Rather, the invention comprises any novel feature and any combination of features, which includes in particular any 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.