DE102013214219A1 - Laser arrangement for generating frequency-converted laser radiation - Google Patents

Abstract

Proposed is a laser arrangement (1) for generating a frequency-converted laser radiation (2a), comprising a laser resonator (4) formed by two end mirrors (3a, 3b), which comprises a laser-active medium (5), in particular a laser disk, for generating a fundamental laser radiation ( 2b), at least one non-linear medium (8), in particular at least one non-linear crystal, for generating the frequency-converted laser radiation (2a) from the fundamental laser radiation (2b) and at least two in the beam path of the laser resonator (4) arranged aperture (10). According to the invention, an optical grating (11) for selecting a wavelength range of the laser radiation (2b) is arranged in the beam path of the laser resonator (4).

Description

The invention relates to a laser arrangement for generating a frequency-converted laser radiation, comprising a laser resonator formed by two end mirrors, the laser active medium, in particular a laser disk for generating a fundamental laser radiation, at least one non-linear medium, in particular at least one non-linear crystal, for generating a frequency-converted laser radiation from the fundamental laser radiation and at least two arranged in the beam path of the laser resonator diaphragms.

In the case of laser arrangements with intracavity frequency conversion, which are used in continuous wave mode or in pulse mode, it is possible for wavelengths in the laser-active medium to rise which can not be converted by the nonlinear medium or crystal. This is due to the fact that the gain bandwidth of most common laser-active media or laser discs is usually wider than the bandwidth of the wavelengths accepted by the non-linear medium or non-linear crystal for frequency conversion. However, when wavelengths out of the range of acceptance oscillate, this represents a loss corresponding to the efficiency of the laser array. However, to achieve comparatively high efficiency or reduce such losses, it is desirable to have a desired wavelength range from a broader wavelength range to select or, in other words, to stabilize the wavelength in the laser array.

In conventional laser arrangements, such as those from DE 10 2005 025 128 B4 become known continuous wave laser arrangement, are used to stabilize the wavelength etalon. Etalons typically include spaced apart partially transmissive mirrors that together form an optical resonator and an optical filter, respectively. The etalon transmits radiation that fulfills a certain resonance condition. Thus, with the etalon, a narrowband spectral range can be filtered out of broadband radiation. Through the etalon of the DE 10 2005 025 128 B4 known laser arrangement is to be prevented, inter alia, by adjusting its inclination to an optical axis, the oscillation of certain spectral ranges.

However, in the case of laser-active media with a wide amplification band, such as Yb: doped media and laser arrangements with comparatively high laser powers, etalons can not ensure that unwanted wavelengths or spectral ranges are completely suppressed. As a result, isolated wavelengths may disadvantageously swing. If a second etalon is arranged to further stabilize the wavelength in the beam path of such a laser arrangement, however, the two etalons must be positioned or adjusted in geometrically exactly aligned position. In addition, both etalons must be kept at the same temperature to prevent their effects from changing as optical filters. Also, a portion of the radiation absorbed by the laser beam transmitting the etalon absorbs further losses in the laser arrangement. Another part of the radiation is reflected.

The present invention has for its object to provide a laser arrangement mentioned above, which overcomes the disadvantages of the prior art. In particular, an alternative solution for wavelength selection by means of etalons should be specified.

This object is achieved by a laser arrangement of the aforementioned type, which is characterized in that an optical grating for selecting a wavelength range of the laser radiation is arranged in the beam path of the laser resonator. By arranging an (optical) grating in the beam path of the laser resonator, it is possible to selectively select a predetermined wavelength range. In other words, the wavelength of the laser radiation can be effectively "stabilized" by the corresponding use of an optical grating. A certain wavelength range of the laser radiation propagating in the laser radiation is thus adjustable. The wavelength range which can be selected or set by the optical grating is preferably adapted to the acceptance range of the frequency conversion (that is to say to the acceptance range of the non-linear medium for frequency conversion). Ie. the bandwidth of the selected wavelength range and the bandwidth of the acceptance range are set to identical or substantially coincident ranges. As a result, it can be advantageously prevented that wavelengths outside of the acceptance range of the frequency conversion oscillate, which lead to losses in the laser arrangement.

Moreover, the disadvantages of using the optical grating when using a wavelength selection etalon can be avoided. In particular, a substantially improved suppression of the unwanted wavelengths or wavelength ranges with only one optical element (with the grating) is possible. The complex matching of temperatures or adjustment several optical elements to each other, for example, two etalons deleted. The geometric adjustment is simplified in the presence of only a single optical grating in the laser array. The optical grating can be designed as a reflection grating or as a transmission grating. Preferably, the optical grating is formed as a reflection grating. The use of a reflection grille reduces absorption-related and also reflection-related losses. Furthermore, the use of the optical grating according to the invention is advantageous in particular for high-power lasers or for lasers with high laser powers.

Instead of the optical grating, any diffractive optical elements can be used according to the invention. For example, the optical grating according to the invention may be formed as a so-called blaze grating with diffraction efficiency maximized for certain diffraction orders. This maximized diffraction efficiency can be achieved for the so-called blaze wavelength. In addition to the wavelength of the laser radiation, the diffraction efficiency of optical gratings basically also depends on the grating parameters (for example the grating constant of the optical grating) and on the angle of incidence of the incident laser radiation. Laser radiation of other (unwanted) wavelength or incident at other angles of incidence laser radiation is diffracted with reduced efficiency. By varying these parameters (lattice parameters, angles of incidence of the laser radiation, etc.), specific wavelengths of the laser radiation can be selectively selected.

The laser-active medium or the laser disk is pumped by a pumping light arrangement, which provides a pump radiation, in a known manner. The non-linear medium or the non-linear media for frequency conversion or the non-linear crystals are typically arranged inside the resonator, in particular in the beam path between an output mirror and an end mirror of the laser resonator. It is also possible to arrange at least one deflecting mirror between the outcoupling mirror and the end mirror. For frequency conversion, for example, a nonlinear medium can be provided, by means of which a frequency doubling is achieved (SHG: second harmonic generation; To achieve a frequency tripling or frequency quadrupling, for example, two non-linear media or two non-linear crystals may be provided. By arranged in the beam path of the laser resonator aperture, the beam direction and the beam position in the laser resonator, which may differ from a desired direction or a desired position, for example, due to spatial misalignment of the end mirror of the laser resonator, stabilized or fixed. Thus, the at least two apertures arranged in the beam path of the laser resonator prevent the laser radiation from escaping to a different frequency due to a change in the beam direction in which the angle of incidence changes to the optical grating. This can also be prevented that the spectral width increases, d. H. that several different wavelengths occur and thus increase the losses in the laser resonator. The diaphragms are preferably arranged in sections of the beam path of the laser resonator, in which the fundamental laser radiation propagates.

Fundamental laser radiation propagates, for example, in sections of the beam path in which the laser-active medium or the laser disk for generating the fundamental laser radiation is arranged and which are limited at one end by an end mirror of the laser resonator and the other end by a decoupling point. For example, at the decoupling point, a coupling-out mirror designed as a dichroic mirror may be provided, which transmits frequency-converted laser radiation and reflects fundamental laser radiation. The laser arrangement according to the invention can be used both in continuous wave mode and in pulse mode.

In a preferred embodiment, the optical grating is arranged between the end mirrors of the laser resonator. Then, the optical grating forms a deflecting mirror arranged in the beam path of the laser resonator between the end mirrors. The optical grating is arranged, in particular, in a section of the beam path in which the fundamental laser radiation propagates, so that the fundamental laser radiation is deflected by the optical grating.

In another preferred embodiment, the optical grating forms one of the end mirrors of the laser resonator. This eliminates at least one used as an end mirror conventional reflection mirror, whereby the typically occurring losses can be avoided or at least reduced. The optical grating is arranged as an end mirror usually at the end of a portion of the beam path of the laser resonator on which the fundamental laser radiation is reflected.

In a preferred development of the preceding embodiment, the optical grating is arranged with respect to the optical axis of the laser radiation in the Littrow arrangement. As a result of the optical grating aligned obliquely in accordance with the Littrow arrangement with respect to the optical axis of the incident laser radiation, the laser radiation incident at an angle of incidence is absorbed identical angle of reflection diffracted at the optical grating. The incident and failing laser radiation (the optical axes of the corresponding laser beams) thus run collinear to each other. The laser radiation is thus diffracted back in the direction of the incident laser radiation, whereby the optical grating takes over the function of the end mirror.

An embodiment in which the optical grating is a dielectric grating is also preferred. Dielectric gratings are particularly suitable for being operated resonator-internally at high laser powers.

An embodiment of the laser arrangement in which at least one aperture is directly adjacent to the optical grating is also preferred. As a result, the laser radiation propagating in the laser resonator hits the diaphragm before it hits the optical grating. The diaphragm is thus arranged in the beam path of the laser resonator such that the beam position on the optical grating (or the beam impingement point on the optical grating and / or the beam impingement direction) are set or adjusted. Between the optical grating and the diaphragm then no further optical elements are arranged, which could influence the beam position (in this section of the beam path). In the event that a plurality of diaphragms are provided in the beam path, it is further preferred that no further optical elements are arranged between the first and optionally the further diaphragm, so that the beam position of the laser radiation by the (immediately successively traversed) aperture fixed or is set. The aperture directly adjacent to the optical grating is viewed in the propagation direction of an incident on the optical grating laser beam the optical grating immediately upstream. Viewed in the propagation direction of a laser beam which emerges from or reflects off the optical grating, the diaphragm is arranged directly downstream of the optical grating.

In a further preferred embodiment, at least one aperture is formed as a pinhole. Aperture diaphragms limit (usually circular) the aperture of the optical system and form so-called hard diaphragms. The opening in the at least one aperture of the pinhole can be variably adjustable. Both diaphragms can also be designed as pinhole diaphragms. Preferably, the two pinhole apertures in the laser resonator are then arranged in a section of the beam path between an end mirror and the laser-active medium (the laser disk) or between the laser-active medium and the output coupling mirror.

An embodiment in which at least one first diaphragm is formed by the pumped region on the laser-active medium is also preferred. In this way, the laser-active medium or the laser disk which generates the fundamental laser radiation can be used as a ("soft") diaphragm. Since the unpumped outer region of a laser-active medium, for example the unpumped region of a laser disk with ytterbium-doped laser materials (Yb: YAG etc.), has an absorbing or non-amplifying effect for laser radiation, it forms one in connection with the pumped region, ie the pump leak called soft aperture: In the pumped interior, d. H. the Pumpfleck, takes place an amplification of the laser radiation, whereas in the unpumped outdoor area, the laser radiation is absorbed or not amplified. The size of the pumped area effectively defines the aperture of the corresponding aperture. The size of the pumped area is usually smaller than the size of the laser-active medium (or the laser disk). "Soft" diaphragms can advantageously take on the function of, for example, "pinhole" shaped "hard" diaphragms with comparatively reduced diffraction losses.

In a preferred embodiment of the preceding embodiment, additional deflecting mirrors are arranged in the beam path of the laser resonator, which direct the laser radiation onto the pumped region several times per intracavity circulation of the laser radiation. On the one hand, a higher gain is achieved by passing through the pumped area several times. On the other hand, the laser radiation, which has already been directed onto the pumped area and amplified by the laser active medium and influenced by the influence of the pumped area as a "soft" diaphragm, can be directed a further (second) time to the same laser-active medium Re-laser radiation in terms of gain and determining the beam position can be influenced. The additional deflection mirrors are typically located in a portion of the laser cavity in which fundamental laser radiation propagates.

In a preferred alternative development of the preceding embodiment, the laser resonator has in its beam path at least one further laser-active medium for generating the fundamental laser radiation, wherein at least one second diaphragm is formed by the pumped region on the further laser-active medium. As a result, the laser radiation already impinged on the pumped region of the one laser-active medium and amplified by this laser-active medium and influenced by the influence of the pumped region of this laser-active medium as a "soft" diaphragm can once again (second) strike the further second laser-active medium be directed, whereby the laser radiation is again affected in terms of gain and determination of the beam position. The fact that two different laser-active media are traversed by the laser radiation, the laser radiation can be influenced differently by each medium. By passing through several laser-active media can also be achieved a higher gain.

Finally, a development is preferred in which the size of the pumped region or the sizes of the pumped regions are adjustable. The adjustment can be made by the choice of the pump jet diameter (the cross-sectional size of the pump jet). By influencing the pump beam diameter, the ratio of the size of the pumped region of the laser-active medium to the unpumped outer region of the laser-active medium can be varied. The pump beam diameter can be increased or decreased, for example, by the pumping unit generating the pumping unit for supplying energy into the laser-active medium or by suitable optics.

Further advantages and advantageous embodiments of the subject invention will become apparent from the description, the claims and the drawings. Likewise, the features mentioned above and the features listed further can be used individually or in combination in any combination. The embodiments shown and described are not to be understood as exhaustive enumeration, but rather have exemplary character for the description of the invention. The figures of the drawing show the subject matter according to the invention in a highly schematized manner and are not to be understood to scale.

Show it:

1 a first embodiment of a laser arrangement according to the invention;

2 a second embodiment of a laser arrangement according to the invention;

3 a third embodiment of a laser arrangement according to the invention;

4 A fourth embodiment of a laser arrangement according to the invention, and

5 one concerning the 1 - 4 alternative arrangement of a reflection grating in the beam path of the laser arrangement;

6a another alternative geometric arrangement of a reflection grating;

6b another alternative geometric arrangement of a transmission grating; and

7 an alternative geometric arrangement of optical elements in the laser resonator for coupling frequency-converted radiation.

1 shows a laser arrangement 1 for generating a frequency-converted laser radiation 2a with one through two end mirrors 3a . 3b formed laser resonator 4 , The laser resonator 4 comprises a designed as a laser disk laser active medium 5 for generating a fundamental laser radiation 2 B , Such laser-active media 5 For example, Yb or Nd may be doped laser crystal slices for cooling and positioning with a heat sink 6 are connected. During operation of the laser array 1 is by means of a in 1 Pumplichtanordnung not shown pump radiation to a pumped area (a pump leak 7 ) of the laser-active medium 5 irradiated to this to generate the fundamental laser radiation 2 B (by population inversion) in the laser-active medium 5 supply required pump power.

The laser resonator 4 also has a non-linear medium formed as SHG crystal (SHG: second harmonic generation) 8th for generating the frequency-converted (or frequency-doubled) laser radiation 2a from the fundamental laser radiation 2 B and two in the beam path of the laser resonator 4 arranged and as pinhole 9 trained irises 10 on. In the beam path of the laser resonator 4 is still one as a reflection grating 11 formed optical grating, with respect to the optical axis 12 the laser radiation 2 B arranged in the so-called Littrow arrangement. As a result, the α is at an angle of incidence α on the reflection grating 11 incident fundamental laser radiation 2 B at an identical angle of incidence β as at the reflection grating 11 diffracted laser radiation 2 B (in the laser resonator 4 ) bent back. In the beam path between the laser-active medium 5 and the nonlinear medium 8th is also a Auskoppelspiegel 13 in the laser resonator 4 arranged.

During operation of the laser arrangement 1 spreads from the laser-active medium 5 generated fundamental laser radiation 2 B in the beam path of the laser resonator 4 between the end mirrors 3a . 3b and is doing both from the end mirrors 3a . 3b even as one of the heat sink 6 facing side 14 of the laser-active medium 5 formed reflective coating and that for the fundamental laser radiation 2 B reflective dichroic Auskoppelspiegel 13 reflected. In the in the 1 lower portion of the beam path of the laser cavity 4 (between the Auskoppelspiegel 13 and the lower right end mirror 3b ) also propagates through the nonlinear medium 8th (or the SHG crystal) generated frequency-converted laser radiation 2a out. The Indian 1 right end mirror 3b is therefore for both the fundamental and the frequency-converted laser radiation 2a . 2 B reflective. The dichroic Auskoppelspiegel 13 is for the frequency-converted laser radiation 2a transmissive, so that of the nonlinear medium 8th generated frequency-converted laser radiation 2a as output beam 15 from the laser arrangement 1 or from the laser resonator 4 exit.

In laser arrangements, which are like the above-described laser arrangement 1 , a laser resonator formed of end mirrors, a laser disk for generating a fundamental laser radiation, and a non-linear crystal for generating a frequency-converted laser radiation, it is possible that the fundamental laser radiation generated by the laser disk has wavelengths that can not be converted by the nonlinear crystal. As a result, however, losses can occur which disadvantageously reduce the performance of such laser arrangements.

By the arrangement of the reflection grating 11 in the beam path of the laser resonator 4 the laser arrangement 1 However, it can specifically target a wavelength range of the (fundamental) laser radiation 2 B be selected to the acceptance of the frequency conversion (ie to the acceptance range of the non-linear medium 8th for frequency conversion) is adjusted. In particular, the bandwidth of the selected wavelength range of the fundamental laser radiation 2 B be chosen such that they match the bandwidth of the acceptance range of the non-linear medium 8th matches. Such a "stabilization" of the wavelength, the aforementioned losses can be reduced or even completely prevented and thus the performance of the laser array 1 be improved. The reflection grid 11 is not only for the selection of a wavelength range of the laser radiation 2 B but also forms the one (in the 1 upper) end mirror 3a of the laser resonator 4 out.

In addition, the arrangement of the two affects as pinhole 9 trained irises 10 in the beam path of the laser resonator 4 advantageous to the beam direction or beam position of the (fundamental) laser radiation 2 B out: It can for example be the result of misalignments of the end mirror 3a . 3b resulting deviations of the beam position are counteracted. In a particularly advantageous manner is through the two pinhole 9 prevents the angle of incidence α on the reflection grating 11 by an undesired shift of the optical (beam) axis 12 changes. The above-described advantageous effect of the arrangement of the reflection grating 11 in the beam path of the laser resonator 4 will therefore continue to be supported. The sizes of the apertures 16 the two pinholes 9 can be adjustable, so that on the beam position correcting effect of the aperture 10 each can be specifically influenced.

At the in 2 shown laser arrangement 1 is only a first as a pinhole 9 trained aperture 10 in the beam path of the laser resonator 4 arranged. The as pinhole 9 trained aperture 10 is the optical reflection grating 11 directly adjacent, ie in a section of the beam path between this aperture 10 and the reflection grating 11 are no further the laser radiation 2 B arranged influencing optical elements. This supports the stabilization of the beam position of the fundamental laser radiation 2 B on the reflection grid 11 ,

Through the pump leak 7 or the pumped area on the laser-active medium 5 is compared to that for the laser radiation 2 B absorbent or non-reinforcing unpumped exterior 17 of the laser-active medium 5 further in the beam path of the laser resonator 4 a second (so-called "soft") aperture 10 educated. In the area of the pump leak 7 becomes the laser radiation 2 B reinforced and in the unpumped outdoor area 17 absorbed or not reinforced. By suitable optics or devices of the pumping light arrangement, not shown can the size of the pump leak 7 (The diameter of the laser-active medium 5 projected pump radiation) targeted and thus to the beam position correcting effect of the soft diaphragm 10 Be influenced. The diameter of the pump leak 10 is usually smaller than the diameter of the laser-active medium 5 , Through the as pinhole 9 trained aperture 10 and the soft aperture 10 becomes the beam position of the fundamental laser radiation 2 B on the reflection grid 11 fixed or stabilized in terms of their position and direction (an undesirable change in the angle of incidence α on the reflection grating 11 and an undesirable change in the impact point on the reflection grating 11 are prevented).

At the in 3 illustrated laser arrangement 1 points the laser resonator 4 in addition to the first laser-active medium 5 in his beam path another laser-active medium 18 for generating the fundamental laser radiation 2 B on. Both through the first laser-active medium 5 or its pump leak 7 as well as the pump leak 7 on the further laser-active medium 18 are ("soft") apertures 10 formed in the above sense. Also in the case of the further laser-active medium 5 can the size of the pump leak 7 be adjustable accordingly. To laser radiation 2 B from a laser-active medium 5 to the other laser-active medium 18 to judge is in the beam path between both media 5 . 18 another deflection mirror 19 arranged. The through the pump leak 7 of the first laser-active medium 5 formed aperture 10 is the optical reflection grating 11 immediately adjacent. The trained as a dichroic mirror Auskoppelspiegel 13 reflects the fundamental laser radiation 2 B whereas he uses the frequency-converted laser radiation 2a transmitted.

In 4 is another laser arrangement 1 represented, in accordance with the laser arrangement of 3 per resonator-internal circulation of the laser radiation 2 B the laser radiation 2 B several times on the pump leak 7 of the laser-active medium 5 meets. The laser-active medium acts here 5 in a sense also as a deflection mirror. In contrast to 3 indicates the laser arrangement 1 or the laser resonator 4 of the 4 but only a single laser-active medium 5 for generating fundamental laser radiation 2 B on. For multiple alignment of the laser radiation 2 B on the laser-active medium (or on the pump leak 7 of the laser-active medium 5 ) are in the beam path of the laser resonator 4 a first and a second Zusatzumlenkspiegel 20 arranged. For example, from the Auskoppelspiegel 13 in the direction of the laser-active medium 5 reflected fundamental laser radiation 2 B in the pump leak 7 on the laser-active medium 5 On, there is the direction of the first additional deflecting mirror 20 reflected, then at the first Zusatzumlenkspiegel 20 in the direction of the second Zusatzumlenkspiegels 20 deflected and finally again towards the laser-active medium 5 directed where the laser radiation 2 B another (second) time in the pump leak 7 impinges before the laser radiation 2 B Finally, in the direction of the reflection grating 11 is reflected. The through the laser-active medium 5 or the pump leak 7 formed aperture 10 is thus traversed several times. The size of the pump leak 7 can, as described above, be adjustable.

5 shows an example of an alternative arrangement possibility of the end mirror 3a forming reflection grating 11 according to the section A of 3 , Instead of in the 1 to 4 illustrated Littrow arrangement of the reflection grating 11 It is also possible that the end mirror 3a forming reflection grids 11 at a 90 ° angle to the optical axis 12 the laser radiation 2 B to arrange and thus cause a angle of incidence corresponding to the angle of incidence. The reflection grid 11 may in particular be a dielectric grid.

In 6a is another alternative arrangement possibility of the reflection grating 11 shown in the laser resonator, wherein the reflection grating 11 in addition to the function of the wavelength selection takes over the function of a deflection mirror in the laser resonator. The reflection grid 11 is between the end mirrors 3a . 3b of the laser resonator (in 6 is just an end mirror 3a shown) and may also be formed, for example, as a dielectric grid.

In the 6b is another alternative arrangement possibility as a transmission grating 11 formed optical grating shown. The transmission grating 11 is between the end mirrors 3a . 3b of the laser resonator (in 6b is just an end mirror 3a shown).

7 Finally, shows an alternative embodiment of the portion of the beam path of the laser resonator in which the frequency-converted laser radiation 2a spreads. In the 7 is between the dichroic Auskoppelspiegel 13 and the SHG crystal end mirror 3b another deflection mirror 21 arranged. The frequency-converted laser radiation 2a thus experiences before its decoupling as output beam 15 a deflection at the deflection mirror 21 ,

In principle, it is also possible that by a reflective coating on the laser-active medium 5 that the heat sink 6 facing, an end mirror 3a . 3b of the laser resonator 4 is trained. Furthermore, the end mirror 3a . 3b and / or output mirror 13 and / or the deflection mirror 19 . 21 (also the Zusatzumlenkspiegel 20 ) have a plane, concave, convex, cylindrical concave, cylindrical convex or toric surface. Alternatively, the deflecting mirrors 19 . 21 (also the Zusatzumlenkspiegel 20 ) may be formed by transmissive elements, such as lens elements.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102005025128 B4 [0003, 0003]

Claims (12)

Laser arrangement ( 1 ) for generating a frequency-converted laser radiation ( 2a ), with one through two end mirrors ( 3a . 3b ) formed laser resonator ( 4 ), which is a laser-active medium ( 5 ), in particular a laser disk, for generating a fundamental laser radiation ( 2 B ), at least one non-linear medium ( 8th ), in particular at least one non-linear crystal, for generating the frequency-converted laser radiation ( 2a ) from the fundamental laser radiation ( 2 B ) and at least two in the beam path of the laser resonator ( 4 ) ( 10 ), characterized in that in the beam path of the laser resonator ( 4 ) an optical grating ( 11 ) for selecting a wavelength range of the laser radiation ( 2 B ) is arranged. Laser arrangement according to claim 1, characterized in that the optical grating ( 11 ) between the end mirrors ( 3a . 3b ) of the laser resonator ( 4 ) is arranged. Laser arrangement according to claim 1, characterized in that the optical grating ( 11 ) one of the end mirrors ( 3a . 3b ) of the laser resonator ( 4 ) trains. Laser arrangement according to claim 3, characterized in that the optical grating ( 11 ) with respect to the optical axis ( 12 ) of the laser radiation ( 2 B ) is arranged in the Littrow arrangement. Laser arrangement according to one of the preceding claims, characterized in that the optical grating ( 11 ) is a dielectric grid. Laser arrangement according to one of the preceding claims, characterized in that at least one aperture ( 10 ) the optical grating ( 11 ) is directly adjacent. Laser arrangement according to one of the preceding claims, characterized in that at least one aperture ( 10 ) as a pinhole ( 9 ) is trained. Laser arrangement according to one of the preceding claims, characterized in that at least one first aperture ( 10 ) through the pumped area ( 7 ) on the laser-active medium ( 5 ; 18 ) is formed. Laser arrangement according to claim 8, characterized in that in the beam path of the laser resonator ( 4 ) Additional deflecting mirror ( 20 ) are arranged, the per intracavity circulation of the laser radiation ( 2 B ) the laser radiation ( 2 B ) repeatedly to the pumped area ( 7 ) judge. Laser arrangement according to claim 8, characterized in that the laser resonator ( 4 ) in its beam path another laser-active medium ( 18 ) for generating the fundamental laser radiation ( 2 B ), wherein at least one second aperture ( 10 ) through the pumped area ( 7 ) on the further laser-active medium ( 18 ) is formed. Laser arrangement according to one of claims 8 to 10, characterized in that the size of the pumped area ( 7 ) or the sizes of the pumped areas ( 7 ) are adjustable. Laser arrangement according to one of the preceding claims, characterized in that the optical grating as a reflection grating ( 11 ) is trained.

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