LASER MEDIUM FOR A SOLID-STATE LASER

Abstract

A laser medium, for generating laser light, that includes a light exit surface through which the laser light exits from the laser medium during laser operation. The light exit surface has a boundary which is defined by at least one chamfer or groove.

Claims

1. A laser medium for generating a laser light, the laser medium is in a solid state, and the laser medium comprises: a light exit surface, through which the laser light exits from the laser medium during laser operation, and the light exit surface has a boundary which is defined by one of at least one chamfer and at least one groove.

2. The laser medium according to claim 1, wherein a ratio of a surface area to a volume of the laser medium is in between 0.8 and 10.

3. The laser medium according to claim 1, wherein the light exit surface has a boundary on all sides which is defined by one of the at least one chamfer and the at least one groove.

4. The laser medium according to claim 1, wherein during laser operation the light exit surface serves as an aperture and one of the at least one chamfer and the at least one groove serves as an aperture stop in order to shape a specific beam profile.

5. The laser medium according to claim 1, wherein during laser operation one of the at least one chamfer and the at least one groove serves to influence a mode profile during laser operation in a defined manner in order to at least one of bring about specific beam properties of the laser light and improve a beam quality of the laser light.

6. The laser medium according to claim 1, wherein the laser medium has a longitudinal axis, and the laser medium is embodied as a laser rod having a first end face including the light exit surface, a second end face opposite the first end face, and a lateral surface.

7. The laser medium according to claim 6, wherein the light exit surface is planar and extends at least one of perpendicularly to the longitudinal axis of the laser medium and parallel to the second end face of the laser rod.

8. The laser medium according to claim 6, further comprising a reflective coating applied on at least one of the second end face, the lateral surface, and one of the at least one chamfer and the at least one groove.

9. The laser medium according to claim 1, wherein the laser medium has a cross-sectional area which is uniform over a part of a length of the laser medium, perpendicular to a longitudinal axis of the laser medium.

10. The laser medium according to claim 1, wherein relative to a cross-sectional area perpendicular to a longitudinal axis of the laser medium, the light exit surface is at least one of smaller, is laterally offset, is geometrically dissimilar, and has a different number of vertices.

11. The laser medium according to claim 1, wherein the boundary which is defined by one of a circumferential chamfer and a circumferential groove.

12. The laser medium according to claim 1, wherein the light exit surface is rectangular and has boundaries which are defined by one of a plurality of chamfers and a plurality of grooves.

13. The laser medium according to claim 1, wherein the light exit surface is circular or elliptic and is bounded by a cone-shaped chamfer in such a way that the chamfer is defined by a surface on a cone whose axis extends parallel or obliquely with respect to a longitudinal axis of the laser medium.

14. The laser medium according to claim 1, wherein the light exit surface is geometrically dissimilar relative to a cross-sectional area perpendicular to a longitudinal axis of the laser medium.

15. The laser medium according to claim 1, further comprising a host material and, embedded therein, a laser-active material for a stimulated emission of photons, wherein the host material comprises one of glass and crystal.

16. The laser medium according to claim 15, wherein the host material is selected from a group of phosphate glasses, comprising phosphate glasses having a designation of one of LG960, LG950, and LG940.

17. The laser medium according to claim 15, wherein the laser-active material includes at least one of ytterbium ions, erbium ions, neodymium ions, praseodymium ions, samarium ions, europium ions, gadolinium ions, terbium ions, dysprosium ions, holmium ions, thulium ions, cerium ions, chromium ions, cobalt ions, vanadium ions, nickel ions, molybdenum ions, and titanium ions.

18. The laser medium according to claim 1, wherein at least one of a concentration of the ytterbium ions is in a range of 510.sup.20 cm.sup.3 to 3010.sup.20 cm.sup.3, a concentration of the erbium ions is in a range of 0.110.sup.20 cm.sup.3 to 210.sup.20 cm.sup.3, a concentration of the chromium ions is in a range of 0 to 0.210.sup.20 cm.sup.3, and a concentration of the neodymium ions is in a range of 0.110.sup.20 cm.sup.3 to 1010.sup.20 cm.sup.3.

19. A laser device, comprising: a laser medium for generating a laser light, the laser medium is in a solid state, and the laser medium includes a light exit surface, through which the laser light exits from the laser medium during laser operation, and the light exit surface has a boundary which is defined by one of at least one chamfer and at least one groove; a pump source for introducing pump light into the laser medium; and a resonator for multiple reflection of photons, wherein the resonator includes one of an output coupling mirror formed by a partly reflective coating and an end mirror formed by a highly reflective coating.

20. A method for producing a laser, comprising: providing a laser medium having a light exit surface, a lateral surface, and at least one edge, and the at least one edge forms a transition between the light exit surface and the lateral surface of the laser medium; and chamfering the at least one edge by at least one of grinding, polishing, and milling away the at least one edge.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0095] The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0096] FIGS. 1a-1b show laser devices having a laser rod, a pump source and a resonator;

[0097] FIGS. 2a-2c show a square laser rod having a centrally positioned rectangular aperture and chamfers of 45 degrees;

[0098] FIGS. 3a-3c show a square laser rod having a centrally positioned rectangular aperture and chamfers of different angles;

[0099] FIGS. 4a-4c show a square laser rod having a centrally positioned round aperture and a cone-shaped chamfer, wherein the axes of symmetry of the laser rod and of the chamfer are identical;

[0100] FIGS. 5a-5c show a square laser rod having a round aperture positioned in a manner displaced relative to the center, and having a cone-shaped chamfer, wherein the axes of symmetry of the laser rod and of the chamfer are parallel;

[0101] FIGS. 6a-6c show a square laser rod having an elliptic aperture and a cone-shaped chamfer, wherein the axes of symmetry of the laser rod and of the chamfer extend obliquely with respect to one another;

[0102] FIGS. 7a-7c show a square laser rod having a centrally positioned elliptic aperture and a chamfer of 45 degrees;

[0103] FIGS. 8a-8b show a square laser rod having a centrally positioned round aperture and a groove (step) embodied as a fold, wherein the axes of symmetry of the laser rod and of the step are identical;

[0104] FIGS. 9a-9b show a round laser rod having a centrally positioned round aperture and a stepped groove (fold), wherein the axes of symmetry of the laser rod and of the fold are identical;

[0105] FIGS. 10a-10b show a round laser rod having a round aperture arranged in a non-centered manner, and having a stepped groove (fold), wherein the axes of symmetry of rod and fold are parallel;

[0106] FIGS. 11a-11b show a round laser rod having a centrally positioned round aperture and a stepped groove (fold), wherein the axes of symmetry of rod and fold are identical and wherein edges adjoining the lateral surface are additionally provided with a safety chamfer;

[0107] FIGS. 12a-12b show a round laser rod having a centrally positioned round aperture and a stepped groove (fold), wherein the axes of symmetry of rod and fold are identical and wherein all edges are additionally provided with a safety chamfer embodied as a rounded portion;

[0108] FIGS. 13a-13b show a round laser rod having a centrally positioned octagonal aperture;

[0109] FIGS. 14a-14b show a round laser rod having a centrally positioned round aperture and a slitted groove (round slot), wherein the axes of symmetry of rod and slot are identical;

[0110] FIGS. 15a-15b show a round laser rod having a centrally positioned round aperture and a slitted groove (round slot), wherein the axes of symmetry of rod and slot are identical and wherein additional (non-aperture-effective) safety chamfers are provided;

[0111] FIGS. 16a-16c show a parallelepipedal laser rod having a rectangular aperture and chamfers at three of the four sides of the light exit surface, such that the latter directly adjoins one of the side surfaces;

[0112] FIGS. 17a-17c show a parallelepipedal laser rod having a rectangular aperture and chamfers at three of the four sides of the light exit surface, such that the latter directly adjoins one of the side surfaces and wherein this side surface is a pump light surface and the other side surfaces are reflectively coated;

[0113] FIGS. 18a-18c show a laser rod having a round aperture positioned in a manner displaced relative to the center, and having a cone-shaped chamfer, wherein the axes of symmetry of rod and chamfer are parallel and wherein the aperture is displaced toward a longitudinal edge (edge parallel to the longitudinal axis of the laser medium) and wherein a pump light entrance surface is polished at said longitudinal edge and wherein the four side surfaces are coated with a mirror layer that is reflective for pump light;

[0114] FIGS. 19a-19b show a square laser rod having a centrally positioned rectangular aperture and chamfers of different angles, wherein (a) the chamfered side of the laser rod is (partly) reflectively coated and the other side of the laser rod is antireflection-coated, or (b) the chamfered side of the laser rod is antireflection-coated and the other side of the laser rod is (partly) reflectively coated; and

[0115] FIGS. 20a-20c show a square laser rod having a centrally positioned rectangular aperture and two pairs of chamfers on opposite sides of the laser rod, wherein chamfers of 45 degrees are involved.

[0116] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

[0117] Referring to FIG. 1a, an exemplary and greatly simplified laser device 2 includes a laser medium 10, a resonator having an end mirror 12 and an opposite output coupling mirror 14, and also a pump light source 16 for generating pump light 18. The pump light 18 can generate population inversion in the laser medium 10.

[0118] In many laser systems there are further elements within the cavity, such as e.g. saturable absorbers as a Q-switch (e.g. composed of cobalt spinell) in pulsed laser systems.

[0119] In the likewise greatly simplified example shown in FIG. 1b, the laser medium 10 is provided with a coating 15, wherein the coating 15 is a partly reflective coating in order to enable light to be coupled out. The partly reflective coating and the end mirror 12 serve as a resonator. As is evident to the person skilled in the art, conversely, a highly reflective coating together with an end mirror can also serve as a resonator.

[0120] With regard to both examples in FIGS. 1a and 1b, laser modes 22 can build up oscillations along the optical axis as a result of induced emission of photons by laser-active material in the laser medium and with the support of multiple reflection of photons in the resonator.

[0121] In the examples shown, the laser medium 10 has a chamfer 21. The latter can prevent e.g. (as illustrated) laser modes from forming parallel to the optical axis even where the chamfer 21 is situated. On the other hand the chamfer 21 can influence the mode profile and/or the energy density in the laser medium 10, in particular in transverse or oblique directions, in a targeted manner (not shown here).

[0122] The chamfer 21 furthermore serves in particular as an aperture stop, in such a way that a spatial selection of laser light is effected, in particular in a plane perpendicular to the optical axis. The chamfer 21 accordingly defines the light exit surface 20, which serves as an aperture and through which photons can leave the laser medium. A laser beam 24 shaped by the chamfer 21 is thus generated.

[0123] FIGS. 2 to 20 describe some possible embodiments of laser media having at least one chamfer or groove. The embodiments shown should be understood not to be exhaustive.

[0124] FIGS. 2a-2c show a laser medium 10 embodied as a laser rod in a side view (FIG. 2a), a plan view (FIG. 2b) and in a front view of the light exit surface 20 (FIG. 2c).

[0125] The laser medium 10 has a rectangular, here square, cross section, as can be seen in FIG. 2c. The light exit surface 20 is bounded on all sides by chamfers 21, 23, 25, 27, which taken together act as an aperture stop.

[0126] The chamfers each form transitions to the lateral surface 50 of the laser medium: the chamfer 27 forms a transition to the side surface 32 of the lateral surface 50 and the chamfer 25 forms a transition to the side surface 30 of the lateral surface 50, as can also be seen in the side view in FIG. 2a. Analogously, the chamfer 23 forms a transition to the side surface 42 of the lateral surface 50 and the chamfer 21 forms a transition to the side surface 40 of the lateral surface 50, as can also be seen in the plan view in FIG. 2b.

[0127] As shown, the light exit surface 20 acting as an aperture is embodied in a rectangular fashion, wherein the width B and the height H have different lengths. The cross section of the laser medium 10, which is square here, is accordingly not geometrically similar to the light exit surface.

[0128] The light exit surface 20 may be arranged in a centered manner with respect to the longitudinal axis of the laser medium 10. In other words, the midpoint of the light exit surface 20 lies on the optical axis. To put it another way, there is no lateral offset of the light exit surface 20.

[0129] The angles between the light exit surface 20 and the chamfer surfaces 21, 23, 25, 27 can be identical, in particular obtuse, angles; here they are in each case 135 degrees. The supplementary angle associated with 135 degrees to form 180 degrees is 45 degrees; therefore, reference is also made to a chamfer at 45 degrees. The angles between the chamfer surfaces 21, 23, 25, 27 and the adjoining side surfaces 40, 42, 30, 32 are also in each case identical angles of 135 degrees here.

[0130] Referring to FIGS. 3a-3c, as also in FIGS. 2a-2c, all angles between chamfer surfaces and light exit surface and between chamfer surfaces and lateral surface are obtuse angles. The laser rod once again has a square cross section and a centered, rectangular aperture.

[0131] By comparison with the example in FIGS. 2a-2c, however, the angles between the light exit surface 20 and the chamfer surfaces 21, 23, 25, 27 are not identical. The angles between the chamfer surfaces 21, 23, 25, 27 and the lateral surface 50 are not identical either. The chamfers thus have different inclination angles.

[0132] Generally, without restriction to this example, one or a plurality of chamfers can have different angles in different directions. Owing to the different angles here (by comparison with the laser medium 10 in FIGS. 2a-2c), the chamfering of the laser medium 10 in the direction of its longitudinal axis is identical for the chamfers 21, 23, 25, 27 bounding the light exit surface.

[0133] Referring to FIGS. 4a-4c to 7a-7c, laser media having a non-round cross section (e.g. having a rectangular or square cross section) can have e.g. a round or elliptic light exit surface 20 (aperture). In this case, the chamfer surface can be described for example by a partial surface of a cone surface. This is also referred to as a cone-shaped chamfer.

[0134] FIGS. 4a-4c show a laser medium 10 embodied as a laser rod in a side view (FIG. 4a), a perspective view (FIG. 4b) and in a front view of the light exit surface 20 (FIG. 4c).

[0135] The laser rod has an angular, here square, cross section and a round, here circular, light exit surface 20. In this example, the light exit surface 20 is centered with respect to the axis of symmetry of the rod.

[0136] The chamfer 21 can be designated as a cone-shaped chamfer, in this example also as a conical chamfer, since the chamfer surface can be described by a surface on a right circular cone. The axis of symmetry of this circular cone is identical here to the longitudinal axis of the laser medium 10. In other words, the axis of symmetry of the chamfer or of the chamfer surface is identical to the axis of symmetry of the rod.

[0137] The opening angle of the cone here is 90 degrees. This gives rise to a chamfer of 45 degrees. Generally, the cone can have virtually any desired opening angles required to obtain the desired chamfer angles.

[0138] In the example in FIGS. 4a-4c, the diameter of the light exit surface (aperture) is approximately 80% of the side edge. Without restriction to this example, the light exit surface can have in particular between 10 and 99%, preferably between 20 and 95%, particularly preferably between 30 and 90%, of a cross-sectional area of the laser medium 10 perpendicular to the longitudinal axis thereof.

[0139] Referring to FIGS. 5a-5c, the axis of symmetry of a (circular) cone describing the chamfer surface 21 can be offset relative to the axis of symmetry (longitudinal axis) of the rod but e.g. parallel thereto. In other words, the axis of symmetry of a chamfer, with respect to the optical axis of the rod, can be displaced identically or at a different extent in one or both directions transversely with respect to the longitudinal axis of the rod, such that the light exit surface 20 (aperture) is not centered.

[0140] This embodiment is of interest particularly if energy is not pumped into the laser medium from all side surfaces 30, 40, 32, 42 equally with pump light and the laser beam does not form in the center of the laser rod on account of the energy density distribution. The asymmetrical shape of the laser medium 10 shown in FIG. 5 can accordingly be adapted to an asymmetrical energy density in the laser medium. The parameters for such an adaptation can e.g. also be refined by way of computer simulations.

[0141] Referring to FIGS. 6a-6c, the axis of symmetry of a (circular) cone describing the chamfer surface 21 can extend obliquely relative to the longitudinal axis of the laser medium 10. In accordance with the theory of conic sections, in particular an elliptic light exit surface 20 can thus be obtained. This is the case particularly if the light exit surface 20 is oriented perpendicularly to the longitudinal axis of the rod.

[0142] In other words, the axis of symmetry of the cone-shaped chamfer can be at an angle with respect to the optical axis of the laser medium 10 which is different than zero.

[0143] By virtue of elliptic apertures (light exit surfaces 20), breaks of rotational symmetries on account of asymmetrical geometry of the rod (e.g. rectangular) or on account of pumping can be compensated for in a particularly advantageous manner.

[0144] FIGS. 7a-7c show a laser medium 10 embodied as a laser rod in a side view (FIG. 7a), a plan view (FIG. 7b) and in a front view of the light exit surface 20 (FIG. 7c). The laser medium has an elliptic light exit surface 20 with the same chamfer angle (here 45 degrees) all around.

[0145] An elliptic aperture can accordingly be achieved even if the chamfer always has the same angle. The chamfer surface can accordingly also have two axes of symmetry.

[0146] Furthermore, the chamfer can have different angles in different directions, particularly in the case of an elliptic cone describing the chamfer surface.

[0147] The conic section having the first end face of the laser medium 10 then yields an ellipse corresponding to the light exit surface 20. This holds true, moreover, even if the axis of symmetry of the cone extends parallel to the optical axis of the rod.

[0148] Referring to FIGS. 8a-8b to 12a-12b, the laser medium 10 can have at least one marginal groove 21, in other words a step or a rabbet. Just like a chamfer, the groove 21 can prevent the formation of laser modes parallel to the optical axis in the region of the groove 21. Accordingly (just like a chamfer) the groove 21 defines the boundary of the aperture, that is to say serves in particular as an aperture stop.

[0149] FIGS. 8a-8b to 12a-12c show a laser medium 10 embodied as a laser rod in a side view (FIGS. 8a to 12a) and in a front view of the light exit surface 20 (FIGS. 8b to 12b). The laser rod shown in FIG. 8 has a square cross-sectional area, while the laser rods shown in FIGS. 9a-9b to 12a-12b have a round, more precisely circular, cross-sectional area.

[0150] Referring to FIGS. 11a-11b and 12a-12b, particularly in the case of a groove 21 which defines a boundary for a light exit surface 20, provision can be made for one or more edges of the groove to be chamfered, i.e. provided with a chamfer 26, wherein the term chamfer is intended also not to exclude a rounded portion or a hollow channel, etc. The chamfer 26 can be embodied in particular as a safety chamfer, i.e. can increase the fracture toughness of the laser rod at the respective edge. In other words, a chamfer 26 can be provided at an edge, in particular at an edge of a groove 21, in order to increase the fracture toughness of the laser medium.

[0151] Referring to FIGS. 11a-11b, such a chamfer 26 embodied as a safety chamfer need not be defining for the boundary of the light exit surface. However, a safety chamfer can also be aperture-effective: in FIGS. 12a-12b, the boundary of the light exit surface 20 is defined e.g. by the dashed line. Furthermore, a safety chamfer can also affect the mode profile.

[0152] The laser medium 10 illustrated in FIGS. 13a-13b has a polygonal light exit surface 20, which has a boundary on all sides which is defined by a plurality of chamfers 21 adjoining the light exit surface 20. The boundary on all sides, i.e. the closed edge, of the light exit surface 20 comprises a plurality of straight boundaries, here eight edge sections, such that the light exit surface 20 is embodied as an octagon.

[0153] Referring to FIGS. 14a-14b and 15a-15b, the boundary of the light exit surface 20 can also be defined by a groove 21 which does not adjoin the light exit surface. In this example, the groove 21 can also be referred to as a circumferential slot. The groove 21 typically extends tangentially or transversely with respect to the optical axis or with respect to the longitudinal axis of the laser medium. The groove 21 is arranged in relation to the position along the optical axis in such a way as to suppress the formation of laser modes in the region of the groove 21 parallel to the optical axis. The groove 21 is accordingly aperture-effective, i.e. delimits the aperture to the light exit surface 20.

[0154] In this case the light exit surface 20 is accordingly not bounded by an edge. Rather, the end side of the laser medium comprises the light exit surface 20 as a partial surface. In other words, the light exit surface 20 undergoes transition precisely to a dead region 20 of the end side of the laser medium.

[0155] Referring to FIGS. 15a-15b, chamfers 26 embodied as safety chamfers can furthermore be provided. In this case, the safety chamfers are each situated in the dead region 20 of the end sides of the laser rod and are accordingly not aperture-effective.

[0156] FIGS. 16a-16c and 17a-17c each show a laser medium 10 embodied as a laser rod in a side view (FIGS. 16a and 17a), a plan view (FIGS. 16b and 17b) and in a front view of the light exit surface 20 (FIGS. 16c and 17c).

[0157] Referring to FIG. 16a-16c, a side surface 30 can undergo transition to the light exit surface 20 via only one edge. In other words, this edge between the side surface 30 and the light exit surface 20 is not provided with a chamfer or a groove.

[0158] In general terms, provision can accordingly be made for a first boundary (here the right-hand straight edge section) of the light exit surface 20 to be defined by a side surface 30 of the laser medium, i.e. not by a chamfer or groove at or in the laser medium e.g. at or in said side surface 30.

[0159] Preferably, at the same time, at least one of the other boundaries or the other boundaries, which together with the first boundary define a boundary on all sides of the light exit surface 20 (here the upper, left-hand and lower edge sections), of the light exit surface 20 is/are defined by a chamfer (here the chamfers 21, 23, 27) or a groove.

[0160] Accordingly, the side surface 30 is larger than the opposite side surfaces 32. This may be advantageous in particular for introducing pump light. Accordingly, the side surface 30 is preferably embodied as a pump light surface or comprises a pump light surface.

[0161] Furthermore, chamfers 26 embodied as safety chamfers can be provided along the longitudinal axis of the laser medium in order to increase the fracture toughness. Accordingly, the lateral surface of the laser medium 10 here includes the side surface 30 serving as a pump light surface, the other side surfaces 32, 40, 42 and the chamfers 26.

[0162] Moreover, provision can be made for the laser medium to be mirror-symmetrical with respect to a plane perpendicular to the longitudinal axis. In particular, the laser medium 10 illustrated has respective light exit surfaces 20 and 20b on both end sides, wherein respective aperture-effective chamfers 21, 23, 27 and 21b, 23b, 27b (i.e. chamfers defining the boundary of the light exit surfaces) are provided.

[0163] FIGS. 17a-17c show the laser medium 10 from FIGS. 16a-16c, wherein the lateral surface 50 at least excluding the pump light surface is reflectively coated with a reflective coating 60. Accordingly, pump light 18 from a pump light source 16 can be coupled into the laser medium 10 via the side surface 30. As has been described above, the pumping efficiency can be increased by the reflective coating.

[0164] FIGS. 18a-18b shows a laser medium 10 embodied as a laser rod in a side view (FIG. 18a) and in a front view of the light exit surface 20 (FIG. 18b), wherein the laser medium 10 has a cone-shaped chamfer 21 (in a manner similar to that in FIGS. 5a-5c). The lateral surface 50 excluding a pump light surface is reflectively coated with a reflective coating 60, the reflective coating 60 not being illustrated in FIG. 18a for reasons of clarity.

[0165] With regard to production, provision can be made here firstly for a reflective coating 60 to be applied to at least one part of the laser medium 10, e.g. to at least one part of the lateral surface 50, and then for the pump light surface to be generated by a part of the reflective coating, in particular together with a part of the laser medium 10, being removed again. Furthermore, provision can be made for the at least one chamfer, here the cone-shaped chamfer 21, to be produced after the reflective coating 60 has been applied.

[0166] The pump light surface has been produced here e.g. by chamfering a longitudinal edge of the reflectively coated laser medium 10.

[0167] The laser medium 10 embodied as a laser rod here accordingly has a pentagonal cross section and five side surfaces 30, 31, 32, 40, 42, wherein the side surface 31 is embodied as a pump light surface.

[0168] The light exit surface 20 can be offset laterally, as here, in such a way that the light exit surface 20 is arranged nearer to the pump light surface than to a side surface or the other side surfaces of the laser medium 10. This can be advantageous since the energy density is typically the highest in the vicinity of the pump light surface.

[0169] FIGS. 19a and 19b each show a laser medium 10 embodied as a laser rod in a side view (left) and in a front view of the light exit surface 20 (right).

[0170] The laser rod shown in FIG. 19a has a reflective coating 15 on its chamfered end side, wherein the reflective coating can be embodied as a partly or a highly reflective coating. In other words, the chamfered end side of the laser rod is partly reflectively coated or reflectively coated. If the coating 15 is a partly reflective coating, then the end face on the chamfered end side of the laser rod is typically embodied as a light exit surface. The end face of the laser rod situated opposite the chamfered end side has an antireflection coating 13.

[0171] Conversely, the laser rod shown in FIG. 19b has an antireflection coating 13 on its chamfered end side and a (partly) reflective coating 15 on the opposite end face. If the coating 15 is a partly reflective coating, the end face situated opposite the chamfered end side typically comprises a light exit surface (as partial surface).

[0172] In other words, in the case of laser rods having a reflectively coated or partly reflectively coated end face (and an uncoated or e.g. antireflection-coated opposite end face), the at least one chamfer (or groove) can be situated on either one or the other end side of the laser rod.

[0173] Referring to FIGS. 20a-20c, it is also possible, in particular, to provide chamfers (or grooves) on both end sides simultaneously, in such a way that a boundary of a light exit surface 20 is defined jointly by the chamfers (or grooves) of the chamfers (or grooves) provided on both end sides. In the example shown, the chamfers 21, 23 are situated on one end side and the chamfers 25, 27 on the other end side, wherein these two pairs of chamfers are arranged in a manner rotated by 90 degrees with respect to one another.

[0174] In the case of cylindrical geometries, as shown for instance in FIGS. 9a-9b, 10a-10b, 11a-11b, 12a-12b or 13a-13b, the laser rods shown in the exemplary embodiments have a cylinder diameter of 4 mm and a cylinder height of 60 mm. As explained above, it is also possible to produce significantly smaller cylindrical laser rods having for instance a cylinder diameter of just 1 mm or even only 0.7 mm and a cylinder height of 10 mm or even only 5 mm.

[0175] In the case of parallelepipedal laser rods as laser medium, as shown for instance in FIGS. 2a-2c, 3a-3c, 4a-4c or 5a-5c, 6a-6c, 7a-7c or 8a-8b, these have a parallelepiped length of 30 mm, a parallelepiped width of 5 mm and a parallelepiped height of 5 mm. Here, too, as explained above, significantly smaller parallelepipedal laser rods are possible, having for instance a parallelepiped length of 4 mm, a parallelepiped width of 2 mm and a parallelepiped height of 1 mm or a parallelepiped length of 3 mm, a parallelepiped width of 0.7 mm and a parallelepiped height of 0.7 mm. In this case, the A/V ratio is in a range of between 0.8 and 10, preferably between 1 and 8 and particularly preferably between 2 and 7.

[0176] Generally, embodiments larger than those described above are also possible. In this regard, by way of example, the length of the laser medium can be up to 250 mm or more, and said length can also be up to approximately 500 mm in further embodiments. Furthermore, the cross sections and/or the front side lengths of the laser medium can also be larger than those described above, for example can be up to 25.4 mm or more and, in further embodiments, up to 50 mm.

[0177] What may be of particular interest, however, is producing laser media comprising laser rods on the basis of phosphate glass which have the small dimensions mentioned above.

[0178] While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.