Optical arrangement

Abstract

An optical arrangement (10) comprising a laser-active solid (12), a pump radiation source (14), and a reflector (16). The laser-active solid (12) is slab-shaped and is designed to amplify and / or generate a laser beam (46). The pump radiation source (14) is designed to generate a pump beam (20) that propagates in a direction (24) and passes through the laser-active solid (12) for the purpose of optical pumping. The reflector (16) is arranged downstream of the laser-active solid (12) in the direction (24) of propagation of the pump beam (20) and is designed to reflect the pump beam (20) transmitted through the laser-active solid (12) back onto the laser-active solid (12). The pump beam (20) reflected by the reflector (16) passes through the laser-active solid (12) for the purpose of optical pumping.

Description

[0001] The invention relates to an optical arrangement.

[0002] Optical arrangements are often used for optical pumping of slab lasers. Slab lasers typically have a slab-shaped laser-active solid, particularly in the form of a slab-shaped laser-active crystal.

[0003] Slab-shaped means that the laser-active solid is plate-shaped. In other words, the laser-active solid can be cuboid-shaped, with the height of the laser-active solid being less than its width and length. Such a shape enables better cooling of the laser-active solid, in particular, it improves heat dissipation of the heat generated by amplifying and / or generating a laser beam.

[0004] For the purpose of optical pumping, a pump beam is often coupled into the laser-active solid at one end face of the solid using an optical arrangement. After coupling, the pump beam passes through the solid and is coupled out of the solid at an end face opposite the end face. To amplify an existing laser beam, the beam can be coupled into the solid using an optical arrangement. After coupling, the laser beam passes through the solid and is amplified in an overlap region of the laser beam with the pump beam within the solid.

[0005] EP 1 181 754 A1 discloses an optical amplifier arrangement with a slab-shaped gain medium and two highly reflective mirrors between which the gain medium is arranged.

[0006] The object of the invention is to provide an optical arrangement which enables amplification and / or generation of a laser beam with high efficiency.

[0007] The invention solves these problems by providing an optical arrangement having the features of claim 1. Advantageous embodiments and further developments of the invention emerge from the dependent claims.

[0008] An optical arrangement according to the invention comprises a laser-active solid, a pump radiation source, and a reflector. The laser-active solid is designed to amplify and / or generate a laser beam. The laser-active solid is slab-shaped. The pump radiation source is designed to generate a pump beam that propagates in a propagation direction and passes through the laser-active solid for the purpose of optical pumping. The reflector is arranged downstream of the laser-active solid in the propagation direction of the pump beam. The reflector is designed to reflect the pump beam transmitted through the laser-active solid back onto the laser-active solid. The pump beam reflected by the reflector passes through the laser-active solid for the purpose of optical pumping.

[0009] Advantageously, the optical arrangement enables highly efficient amplification and / or generation of the laser beam by reflecting the unabsorbed portion of the pump beam transmitted through the laser-active solid back onto the laser-active solid, thereby additionally optically pumping the laser-active solid. This allows the utilization of pump radiation that is not absorbed during the initial transmission of the pump beam through the laser-active solid. Advantageously, the optical arrangement enables a uniform distribution of the pump beam power across the laser-active solid, thereby achieving uniform heating of the laser-active solid and thus less impacting the beam quality of the laser beam as it passes through the laser-active solid.

[0010] Optical pumping can be understood as the induction of a population inversion through optical excitation, particularly due to an electron-photon interaction. A population inversion can occur when energy levels of a particle or molecule are not populated with electrons in the way that would be expected without optical excitation at a given temperature. In other words, optical pumping can be a process in which electrons in an atom or molecule are raised from a lower energy level to a higher energy level by means of the pump beam.

[0011] When the pump beam passes through the laser-active solid, the pump beam can optically pump the laser-active solid. Optical pumping involves partial absorption of the pump beam by the laser-active solid, causing a population inversion in the laser-active solid. Optical pumping reduces the power of the pump beam. The transmitted pump beam can be a residual portion of the pump beam generated by the pump radiation source. The transmitted pump beam can be referred to as the pump beam not absorbed by the laser-active solid. The transmitted pump beam can be a portion of the pump beam generated by the pump radiation source that has not optically pumped the laser-active solid after passing through.

[0012] The pump radiation source may be a diode laser and in particular comprise a laser diode.

[0013] The wavelength of the pump beam and the wavelength of the laser beam can differ from each other. The wavelength of the pump beam can be matched to the laser-active solid, in particular to the material of the laser-active solid, in such a way that the laser-active solid is optically pumped by the pump beam. The wavelength of the laser beam can be matched to the laser-active solid in such a way that the laser beam can be amplified by stimulated emission using the laser-active solid.

[0014] The wavelength of the pump beam can be 850 nm to 990 nm, in particular 880 nm to 890 nm, preferably 885 nm. The wavelength of the laser beam can be 1000 to 1180 nm, in particular 1060 nm to 1065 nm. The abbreviation nm refers to the unit nanometer.

[0015] The laser beam can be amplified and / or generated by the laser-active solid by means of stimulated emission. The laser beam and the pump beam can overlap, in particular superimpose, within the laser-active solid. In particular, the laser beam and the pump beam can overlap temporally and spatially within the laser-active solid. The laser beam and the pump beam can overlap within the laser-active solid in such a way that they propagate within the laser-active solid, amplifying the laser beam. The propagation direction of the laser beam and the propagation direction of the pump beam can differ from one another.

[0016] The reflector can be a retroreflector or a mirror, in particular a Bragg mirror. The reflector can have a highly reflective, particularly dielectric, coating for the pump beam. The reflector can be arranged on an end face or an end side of the laser-active solid.

[0017] The reflector can be designed to reflect the transmitted pump beam in such a way that the pump beam is at least partially overlapped, in particular superimposed, with itself within the laser-active solid before reflection by means of the reflector and after reflection by means of the reflector.

[0018] The laser-active solid may have a crystal, in particular a crystal structure. The laser-active solid may also be referred to as a laser crystal.

[0019] In a further development of the optical arrangement, the reflector is configured to reflect the pump beam transmitted through the laser-active solid back with a spatial offset and / or angular offset. The spatial offset is configured such that the pump beam reflected by the reflector impinges on the pump radiation source with less than 5%, in particular 3% or 2%, of its power. This advantageously prevents damage to the pump radiation source by the reflected pump beam and excessive heating of the pump radiation source. In particular, 5%, in particular 3% or 2%, of the power of the reflected pump beam can impinge on the pump radiation source without influencing and / or damaging the pump radiation source.

[0020] In a further development of the optical arrangement, the reflector is configured such that a value of an angle of incidence of the pump beam transmitted through the laser-active solid with respect to the reflector is not equal to 0°. Additionally or alternatively, the reflector is configured such that a value of an angle of reflection of the pump beam reflected by the reflector is not equal to 0° with respect to the reflector. The value of the angle of incidence and the value of the angle of reflection can be the same.

[0021] In one development, the optical arrangement comprises a polarizer. The polarizer is arranged between the pump radiation source and the laser-active solid. The polarizer is configured to filter the pump beam depending on its polarization such that the pump beam has a linear polarization after the polarizer. The optical arrangement comprises a λ / 4 plate. The λ / 4 plate is arranged between the polarizer and the reflector. The λ / 4 plate is configured to convert the linear polarization of the pump beam into a circular polarization of the pump beam and the circular polarization of the pump beam into a linear polarization of the pump beam. The polarizer can be configured to deflect the pump beam depending on its polarization.

[0022] The λ / 4 plate may comprise a birefringent material. The λ / 4 plate may have a fast axis and a slow axis, with the λ / 4 plate delaying the phase of a beam portion polarized parallel to the slow axis by a quarter of the pump beam's wavelength compared to the phase of a beam portion polarized parallel to the fast axis. λ denotes the pump beam's wavelength.

[0023] The polarizer can be configured to filter the pump beam by means of dichroism, reflection, birefringence, scattering, and / or diffraction depending on its polarization. The polarizer can comprise, in particular, a film polarizer, a thin-film polarizer, a wire grid polarizer, a crystal polarizer, a polarizing beam splitter, or a Brewster window.

[0024] The pump beam generated by the pump radiation source may be linearly polarized. The degree of polarization of the linearly polarized pump beam may be greater than 85%, in particular 90% or 95%.

[0025] The polarizer can be arranged such that the pump beam passes through the laser-active solid after passing through the polarizer.

[0026] In a further development of the optical arrangement, the λ / 4 plate is arranged such that the pump beam passes through the λ / 4 plate before being reflected by the reflector, and the pump beam passes through the λ / 4 plate after being reflected by the reflector. This advantageously allows the pump beam to be rotated by 90° in its polarization after being reflected by the reflector and after passing through the λ / 4 plate relative to the polarization of the pump beam before passing through the λ / 4 plate.

[0027] In a further development of the optical arrangement, the λ / 4 plate is designed to change the polarization of the pump beam such that the linear polarization of the pump beam before passing through the λ / 4 plate and the linear polarization of the pump beam reflected by the reflector after passing through the λ / 4 plate are orthogonal to each other.

[0028] In a further development of the optical arrangement, the polarizer is configured to filter the pump beam reflected by the reflector depending on its polarization such that the pump beam reflected by the reflector impinges on the pump radiation source with less than 5%, in particular 3% or 2%, of its power. This advantageously prevents damage to the pump radiation source by the reflected pump beam. In particular, 5%, in particular 3% or 2%, of the power of the reflected pump beam can impinge on the pump radiation source without influencing and / or damaging the pump radiation source.

[0029] In a further development of the optical arrangement, the reflector is a wavelength-selective element configured to reflect a wavelength of the pump beam more strongly than a wavelength of the laser beam. The reflector's reflectance for the wavelength of the pump beam can be at least 95%, in particular 98%, 99%, 99.9%, or 99.99%. The reflectance of the reflector for the wavelength of the laser beam can be at most 5%, in particular 3%, 1%, 0.5%, 0.3%, or 0.1%.

[0030] In a further development, the reflector is wavelength-selective in such a way that it essentially reflects wavelengths within the absorption band of the laser-active solid. In particular, reflected pump radiation directed backward through the laser-active solid can be largely absorbed or absorbed by the laser-active solid after the double pass. Such wavelength selectivity can also prevent the emission of the pump radiation source from being undesirably shifted to a wavelength that is less well absorbed by the solid.

[0031] In a further development of the optical arrangement, the laser-active solid is formed from a material doped with ytterbium or neodymium ions. For example, the material is or comprises Yb:YAG, Nd:YAG, Yb:LuAG, Yb:CaF2, Yb:CALGO, Yb:Lu2O3, Yb:Sc2O3, Yb:GGG, Yb:YLF, Yb:S-FAP, Nd:YVO4, Nd:GdVO4, Yb:KGW, or Yb:KYW. Advantageously, these materials are particularly suitable for efficient amplification and / or generation of the laser beam and can exhibit low heat generation during amplification and / or generation.

[0032] In one development, the optical arrangement comprises a cooling device for cooling the laser-active solid. The cooling device can be referred to as a heat sink. The laser-active solid can have a touching contact with the cooling device. The cooling device can comprise a first cooling plate and a second cooling plate, wherein the first cooling plate is arranged on a first longitudinal side of the laser-active solid and wherein the second cooling plate is arranged on a second longitudinal side opposite the first longitudinal side. The cooling device can be a water cooling device.

[0033] In a further development of the optical arrangement, the reflector has a curved surface. The reflector is configured such that a curvature of the curved surface is equal to a curvature of a phase front of the pump beam. Advantageously, this maintains a caustic of the pump beam after reflection by the reflector, thereby achieving improved overlap between the pump beam and the laser beam and thus more efficient amplification and / or generation of the laser beam. In particular, a caustic of the pump beam before reflection by the reflector and a caustic of the pump beam after reflection by the reflector can be identical.

[0034] In a further development, the optical arrangement is configured so that the laser beam propagates in one propagation direction and passes through the laser-active solid. The propagation direction of the laser beam and the propagation direction of the pump beam are at an angle of less than 45° to each other in the laser-active solid. This advantageously makes the optical arrangement particularly compact.

[0035] The device preferably comprises an absorber for absorbing the pump radiation reflected by the reflector and directed backward through the laser-active solid. This absorber can be actively cooled. This pump radiation, which in particular has not been absorbed by the laser-active medium, can be directed to this absorber by means of a polarizer and / or reflectors.

[0036] In a further development of the optical arrangement, the pump radiation source has a stabilization element for stabilizing the wavelength of the pump beam. This advantageously results in higher optical pumping efficiency. A spectrum of the pump beam can have a half-width of at most 5 nm, in particular 3 nm or 2 nm. The stabilization element can have a grating, in particular a volume Bragg grating. The stabilization element can be designed as an output mirror of the pump radiation source. The stabilization element can be a bandpass filter, in particular a narrow bandpass filter, with a half-width of at most 5 nm, in particular 3 nm or 2 nm. A reflectance of the stabilization element for the wavelength of the pump beam can be at least 5%, in particular 10% or 15%.

[0037] Further advantages and advantageous embodiments of the invention can be found in the figures, their description, and the patent claims. All features disclosed in the figures, their description, and the patent claims can be essential to the invention both individually and in any combination. They show: Fig. 1 a schematic representation of an embodiment of an optical arrangement according to the invention, Fig. 2 a schematic representation of a laser-active solid of the optical arrangement of Fig. 1, Fig. 3 a detailed view of an area III of Fig. 1, and Fig. 4 a schematic representation of a further embodiment of an optical arrangement according to the invention.

[0038] Fig. 1 schematically shows an optical arrangement 10. The optical arrangement 10 has a laser-active solid 12, a pump radiation source 14 and a reflector 16.

[0039] The pump radiation source 14 is a diode laser and has a laser diode 18 for generating a pump beam 20. The wavelength of the pump beam 20 is 885 nm. The pump radiation source 14 has a stabilization element 22 for stabilizing the wavelength of the pump beam 20. The stabilization element 22 is a volume Bragg grating. The stabilization element 22 is an output mirror of the pump radiation source 14. The reflectance of the stabilization element 22 for the wavelength of the pump beam 20 can be, for example, 5%. The stabilization element 22 is a bandpass filter with a half-width of 2 nm. A spectrum of the pump beam 20 has a half-width of 2 nm.

[0040] The pump beam 20 propagates in a propagation direction 24 and passes through the laser-active solid 12.

[0041] The laser-active solid body 12 is for amplifying and / or generating a non- Fig. 1. The laser-active solid 12 has a crystalline structure. The laser-active solid 12 is formed from Nd:YAG. The wavelength of the pump beam 20 is matched to the material of the laser-active solid 12 such that the laser-active solid 12 is optically pumped with the pump beam 20. The pump beam 20 passes through the laser-active solid 12 for the purpose of optical pumping. Due to the optical pumping, the pump beam 20 is partially absorbed by the laser-active solid 12, causing a population inversion. A remaining portion of the pump beam 20 leaves the laser-active solid 12 as a transmitted pump beam 20.

[0042] The laser-active solid body 12 is slab-shaped.

[0043] The optical arrangement 10 has a cooling device 26 for cooling the laser-active solid-state body 12. The cooling device 26 is designed as a water cooling device. The cooling device 26 has a first cooling plate 28 and a second cooling plate 30. The first cooling plate 28 is arranged on a first longitudinal side of the laser-active solid-state body 12, and the second cooling plate 30 is arranged on a second longitudinal side opposite the first longitudinal side. The cooling device 26 dissipates heat generated in the laser-active solid-state body 12 during the amplification and / or generation of the laser beam.

[0044] Fig. 2 schematically shows the laser-active solid 12 in a view of the first longitudinal side of the laser-active solid 12 without the first cooling plate 30. The laser-active solid 12 has a first end face 42 and a second end face 44 opposite the first end face 42. The pump beam 20 impinges on the first end face 42 and is coupled into the laser-active solid 12 at the end face. The pump beam 20 passes through the laser-active solid 12 from the first end face 42 to the second end face 44. After passing through the laser-active solid 12, the pump beam 20 exits the laser-active solid 12 at the second end face 44 in the form of the transmitted pump beam 20.

[0045] Fig. 2 shows the laser beam 46. The laser beam 46 propagates in a propagation direction 48. The laser beam 46 impinges on the first end face 42 and is coupled into the laser-active solid body 12 at the end face. The laser beam 46 passes through the laser-active solid body 12 from the first end face 42 to the second end face 44. After passing through the laser-active solid body 12, the laser beam 46 exits the laser-active solid body 12 at the second end face 44.

[0046] The propagation direction 48 of the laser beam 46 and the propagation direction 24 of the pump beam 20 differ from each other. An angle 50 between the propagation direction 48 of the laser beam 46 and the propagation direction 24 of the pump beam 20 is less than 45°. In the illustrated embodiment of the Fig. 1 to 3 the angle is 50 15°.

[0047] The laser beam 46 and the pump beam 20 overlap within the laser-active solid 12 for the purpose of amplifying the laser beam 46. The amplification of the laser beam 46 occurs by means of stimulated emission during propagation of the laser beam 46 and the pump beam 20 through the laser-active solid 12.

[0048] Fig. Figure 1 shows that the reflector 16 is arranged downstream of the laser-active solid 12 in the propagation direction 24 of the pump beam 20. The reflector 16 is a plane mirror. The reflector 16 has a dielectric coating that is highly reflective for the pump beam 20. The reflector 16 is a wavelength-selective optical element designed to reflect the wavelength of the pump beam 20 more strongly than a wavelength of the laser beam. The reflectance of the reflector 16 for the wavelength of the pump beam 20 is 99.9%. The reflectance of the reflector 16 for the wavelength of the laser beam is 1%.

[0049] The reflector 16 is arranged such that the pump beam 20 transmitted through the laser-active solid 12 is reflected back onto the laser-active solid 12. The pump beam 20 reflected by the reflector 16 passes through the laser-active solid 12 for the purpose of optical pumping. As a result, the pump beam 20 passes through the laser-active solid 12 bidirectionally. The reflector 16 is configured to reflect the transmitted pump beam 20 such that the pump beam 20 is partially superimposed on itself within the laser-active solid 12 before and after reflection by the reflector 16.

[0050] For reasons of clarity, Fig. 2, the reflected pump beam 20 is not shown. The pump beam 20 reflected by the reflector 16 impinges on the second end face 44 and is coupled into the laser-active solid 12 at the end face. The reflected pump beam 20 passes through the laser-active solid 12 from the second end face 44 to the first end face 42. After passing through the laser-active solid 12, a remaining portion of the reflected pump beam 20 exits the laser-active solid 12 at the first end face 42.

[0051] Fig. 3 shows the reflector 16. The reflector 16 is tilted relative to the transmitted pump beam 20. In other words, the reflector 16 is configured such that a value of an angle of incidence 32 of the pump beam 20 transmitted through the laser-active solid 12 relative to the reflector 16 is not equal to 0°. In the illustrated example of the Fig. 1 and Fig. 2, the angle of incidence 32 is 6°. The angle of incidence 32 is limited by the transmitted pump beam 20 and a normal 34 on the reflector 16. In addition, the reflector 16 is configured such that a value of an angle of reflection 36 of the pump beam 20 reflected by the reflector 16 is not equal to 0° with respect to the reflector 16. The value of the angle of incidence 32 and the value of the angle of reflection 36 are equal. The angle of reflection 36 is limited by the reflected pump beam 20 and the normal 34 on the reflector 16.

[0052] Due to the tilted reflector 16, an angle between the propagation direction 24 of the pump beam 20 and a propagation direction of the reflected pump beam 20 is 12°.

[0053] Because the angle of incidence 32 and the angle of reflection 36 are not equal to 0°, the reflected pump beam 20 impinges on the pump radiation source 14 with less than 3% of its power. The reflected pump beam 20 is guided past the pump radiation source 14 with its remaining 97% of power. This prevents excessive heating of the pump radiation source due to absorption of the reflected pump beam 20 and / or a change in the wavelength of the pump beam 20 due to coupling of the reflected pump beam 20 into the pump radiation source 14.

[0054] The optical assembly 10 may have a first lens 38 and a second lens 40.

[0055] The first lens 38 is arranged between the pump radiation source 14 and the laser-active solid 12. The first lens 38 is configured to focus the pump beam 20 into the laser-active solid 12. A focus of the pump beam 20 formed by the first lens 38 is located within the laser-active solid 12.

[0056] The second lens 40 is arranged between the laser-active solid 12 and the reflector 16. The second lens 40 is configured to collimate or image the transmitted pump beam 20. The pump beam 20 impinges on the reflector 16 in a collimated or imaged state.

[0057] Alternatively or additionally, the second lens 40 can be integrated into the reflector 16 and / or formed on the reflector 16. For example, the reflector 16 itself can be curved for this purpose.

[0058] The reflector 16 can, in principle, be integrated into the laser-active solid body 12 or arranged or formed on the laser-active solid body 12. It is therefore not necessarily designed as a separate component.

[0059] In Fig. 4 schematically shows a further embodiment of an optical arrangement, wherein in the embodiment of the Fig. 1 to 3 and in the embodiment of the Fig. 4 the same reference numerals are used for identical and functionally equivalent elements and in this respect the above explanations regarding the embodiment of the Fig. 1 to 3, so that essentially only the existing differences in the embodiment of the Fig. 4 is discussed.

[0060] The reflector 16 is arranged so as to be straight relative to the transmitted pump beam 20. In other words, the reflector 16 is configured such that the angle of incidence of the pump beam 20 transmitted through the laser-active solid 12 is 0° relative to the reflector 16. The reflector 16 is configured such that the angle of reflection of the pump beam 20 reflected by the reflector 16 is 0° relative to the reflector 16.

[0061] Due to the straight arrangement of the reflector 16, the angle between the propagation direction 24 of the pump beam 20 and the propagation direction of the reflected pump beam 20 is 0°. In other words, the propagation direction 24 of the pump beam 20 and the propagation direction of the reflected pump beam 20 are parallel to each other. The propagation direction 24 of the pump beam 20 and the propagation direction of the reflected pump beam 20 are opposite to each other.

[0062] The pump beam 20 generated by the pump radiation source 14 is linearly polarized. The degree of polarization of the linearly polarized pump beam 20 is 98%.

[0063] The optical arrangement 10 has a polarizer 52. The polarizer 52 is a thin-film polarizer. The polarizer 52 is arranged between the pump radiation source 14 and the laser-active solid 12. In the illustrated embodiment of the Fig. 4, the polarizer 52 is arranged between the pump radiation source 14 and the first lens 38. The polarizer 52 is configured to filter the pump beam 20 depending on its polarization such that the pump beam 20 is linearly polarized after the polarizer 52. The polarizer 52 is configured to deflect the pump beam 20 depending on its polarization.

[0064] The polarizer 52 is arranged such that the linearly polarized pump beam 20 generated by the pump radiation source 14 passes through the polarizer 52 without power loss.

[0065] The optical arrangement 10 has a λ / 4 plate 54. The λ / 4 plate 54 has a fast axis and a slow axis, with the λ / 4 plate 54 delaying a beam portion of the pump beam 20 that is polarized parallel to the slow axis by a quarter wavelength compared to a beam portion of the pump beam 20 that is polarized parallel to the fast axis. λ denotes the wavelength of the pump beam 20.

[0066] The λ / 4 plate 54 is arranged between the polarizer 52 and the reflector 16. The λ / 4 plate 54 is arranged such that the pump beam 20 passes through the λ / 4 plate 54 before being reflected by the reflector 16, and the pump beam 20 passes through the λ / 4 plate 54 after being reflected by the reflector 16.

[0067] In the illustrated embodiment of the Fig.4, the λ / 4 plate 54 is arranged between the first lens 38 and the laser-active solid 12. The λ / 4 plate 54 is arranged such that the linear polarization of the pump beam 20 is converted into a circular polarization after passing through the λ / 4 plate 54. After passing through the λ / 4 plate 54, the circularly polarized pump beam 20 passes through the laser-active solid 12 and is reflected by the reflector 16. The reflected pump beam 20 then passes through the laser-active solid 12 and the λ / 4 plate 54. The λ / 4 plate 54 is arranged such that the circular polarization of the pump beam 20 reflected by the reflector 16 is converted into a linear polarization after passing through the λ / 4 plate 54. The polarization of the pump beam 20 reflected by the reflector 16 is rotated by 90° after passing through the λ / 4 plate 54 compared to the polarization of the pump beam 20 before passing through the λ / 4 plate 54.In other words, the λ / 4 plate 54 is configured to change the polarization of the pump beam 20 such that the linear polarization of the pump beam 20 before passing through the λ / 4 plate 54 and the linear polarization of the pump beam 20 reflected by the reflector 16 after passing through the λ / 4 plate 54 are orthogonal to each other.

[0068] The pump beam 20 reflected by the reflector 16 strikes the polarizer 52 after passing through the λ / 4 plate 54. The polarizer 52 is configured to filter the pump beam 20 reflected by the reflector 16 depending on its polarization such that the pump beam 20 reflected by the reflector 16 strikes the pump radiation source 14 with less than 2% of its power.

[0069] In another embodiment of an optical arrangement (not shown), the optical arrangement lacks the second lens. Instead of the second lens, the reflector of the optical arrangement (not shown) has a curved surface. The reflector is configured such that a curvature of the curved surface is equal to a curvature of a phase front of the transmitted pump beam.

[0070] In a further embodiment of an optical arrangement (not shown), the reflector is a retroreflector and is configured to reflect the pump beam transmitted through the laser-active solid back with a spatial offset. The spatial offset is configured such that the pump beam reflected by the reflector impinges on the pump radiation source with less than 5%, in particular 3% or 2%, of its power.

[0071] As the embodiments shown and explained make clear, the invention provides an optical arrangement which enables amplification and / or generation of a laser beam with high efficiency. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 1 181 754 A1

[0005]

Claims

[1] Optical arrangement (10), comprising: - a laser-active solid body (12) for amplifying and / or generating a laser beam (46), wherein the laser-active solid body (12) is slab-shaped, - a pump radiation source (14) for generating a pump beam (20) which propagates in a propagation direction (24) and which passes through the laser-active solid (12) for the purpose of optical pumping, - a reflector (16) which is arranged downstream of the laser-active solid (12) in the propagation direction (24) of the pump beam (20) and which is designed to reflect the pump beam (20) transmitted through the laser-active solid (12) back onto the laser-active solid (12), wherein the pump beam (20) reflected by the reflector (16) passes through the laser-active solid (12) for the purpose of optical pumping. [2] Optical arrangement (10) according to claim 1, - wherein the reflector (16) is designed to reflect back the pump beam (20) transmitted through the laser-active solid (12) with a spatial offset and / or angular offset, - wherein the spatial offset is arranged so that the pump beam reflected by the reflector (16) hits the pump radiation source with less than 5% of its power. [3] Optical arrangement (10) according to one of the preceding claims, - wherein the reflector (16) is configured such that a value of an angle of incidence (32) of the pump beam (20) transmitted through the laser-active solid (12) relative to the reflector (16) is not equal to 0°, and / or - wherein the reflector (16) is configured such that a value of an angle of reflection (36) of the pump beam (20) reflected by the reflector (16) relative to the reflector (16) is not equal to 0°. [4] Optical arrangement (10) according to one of the preceding claims, - wherein the optical arrangement (10) comprises a polarizer (52), - wherein the polarizer (52) is arranged between the pump radiation source (14) and the laser-active solid (12), - wherein the polarizer (52) is designed to filter the pump beam (20) depending on its polarization such that the pump beam (20) has a linear polarization after the polarizer (52), - wherein the optical arrangement (10) comprises a λ / 4 plate (54), - wherein the λ / 4 plate (54) is arranged between the polarizer (52) and the reflector (16), - wherein the λ / 4 plate (54) is configured to convert the linear polarization of the pump beam (20) into a circular polarization of the pump beam (20) and the circular polarization of the pump beam (20) into a linear polarization of the pump beam (20). [5] Optical arrangement (10) according to claim 4, - wherein the λ / 4 plate (54) is arranged such that the pump beam (20) passes through the λ / 4 plate (54) before being reflected by the reflector (16) and the pump beam (20) passes through the λ / 4 plate (54) after being reflected by the reflector (16). [6] Optical arrangement (10) according to one of claims 4 to 5, - wherein the λ / 4 plate (54) is configured to change the polarization of the pump beam (20) such that the linear polarization of the pump beam (20) before passing through the λ / 4 plate (54) and the linear polarization of the pump beam (20) reflected by the reflector (16) after passing through the λ / 4 plate (54) are orthogonal to one another. [7] Optical arrangement (10) according to one of claims 4 to 6, - wherein the polarizer (52) is configured to filter the pump beam (20) reflected by the reflector (16) as a function of its polarization such that the pump beam (20) reflected by the reflector (16) strikes the pump radiation source (14) with less than 5% of its power. [8] Optical arrangement (10) according to one of the preceding claims, - wherein the reflector (16) is a wavelength-selective element which is designed to reflect a wavelength of the pump beam (20) more strongly than a wavelength of the laser beam (46). [9] Optical arrangement (10) according to one of the preceding claims, - wherein the laser-active solid body (12) is formed from a material which comprises, in particular is, Yb:YAG, Nd:YAG, Yb:LuAG, Yb:CaF2, Yb:CALGO, Yb:CALYO, Yb:GdCOB, Yb:Lu2O3, Yb:Sc2O3, Yb:S-FAP, Yb:GGG, Nd:YVO4, Nd:GdVO4, Yb:KGW, Yb:KYW, Yb:YLF or Yb:YALO. [10] Optical arrangement (10) according to one of the preceding claims, - wherein the optical arrangement (10) has a cooling device (26) for cooling the laser-active solid body (12). [11] Optical arrangement (10) according to one of the preceding claims, - wherein the reflector (16) has a curved surface, - wherein the reflector (16) is configured such that a curvature of the curved surface is equal to a curvature of a phase front of the pump beam (20). [12] Optical arrangement (10) according to one of the preceding claims, - wherein the optical arrangement (10) is arranged so that the laser beam (46) propagates in a propagation direction (48) and passes through the laser-active solid body (12), - wherein the propagation direction (48) of the laser beam (46) and the propagation direction (24) of the pump beam (20) in the laser-active solid (12) have an angle (50) of less than 45° to one another. [13] Optical arrangement (10) according to one of the preceding claims, - wherein the pump radiation source (14) has a stabilization element (22) for wavelength stabilizing the pump beam (20).

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