DE102015106728A1 - Method and system for generating pulsed laser radiation - Google Patents

Abstract

In order to improve a method for generating pulsed laser radiation of a first wavelength at which a solid-state laser is pumped with pump laser radiation of a second wavelength, so that pulsed laser radiation can be generated with high efficiency, it is proposed that the solid-state laser is pumped pulsed with pump pulses of the pump laser radiation and a self-organization time t self-organization of the solid-state laser between two successive pump pulses is predetermined such that the solid-state laser emits at least one laser pulse of the first wavelength by self-organization. Furthermore, an improved system for generating laser pulses is proposed.

Description

The present invention relates to a method for generating pulsed laser radiation of a first wavelength, in which a solid-state laser is pumped with pump laser radiation of a second wavelength.

Furthermore, the present invention relates to a system for generating pulsed laser radiation of a first wavelength, comprising a pump laser and a solid-state laser pumped with the pump laser, which generates pump laser pump laser radiation of a second wavelength.

The generation of high energy laser pulses has become increasingly important in industry in recent years, particularly in material processing. Furthermore, pulse lasers are also used in the medical field, for example in the treatment of eye diseases and for the correction of visual defects. Depending on the application, certain wavelengths and pulse widths are needed.

Solid-state lasers in the form of disk lasers or disk laser systems are suitable for generating short laser pulses. In order to decouple pulses from the resonator of the disc laser, optical switches are used in particular. However, these have the disadvantage that they result in a significant efficiency reduction of the average laser output power, which is on the order of about 50% over the CW output power.

It is therefore an object of the present invention to improve a method and a system of the type described above so that pulsed laser radiation can be generated with high efficiency.

This object is achieved in a method of the type described above according to the invention that the solid-state laser pumped pump pulses of pump laser radiation is pulsed and that a self-organization t _{self-assembly of} the solid state laser between two successive pump pulses is set so that the solid state laser by self-organization at least one laser pulse first wavelength emitted.

The proposed solution according to the invention has the particular advantage that can be completely dispensed with additional optical elements in the resonator of the solid-state laser, such as a disk laser. This is favorable, for example, in the case of a Ho: YAG disk laser, because there occur additional losses in the resonator due to the fact that in the energy transitions of the laser-active ions Ho ³⁺ so-called "up-conversion" effects occur, which is a decoupling of the laser beam from the resonator to about 1%. The proposed method for generating pulsed laser radiation by passive pulsing of the solid-state laser makes it possible, in particular, to dispense with the additional optical elements for coupling out the laser radiation of the first wavelength from the resonator. This makes it possible for solid-state lasers, for example a disk laser in the form of a pulsed Ho: YAG disk laser, to achieve almost the cw output power of 100%. In the proposed method, the formation of laser pulses by self-organization in solid-state laser, also referred to as self-oscillation used. Thus, a maximum laser efficiency of the system can be achieved, because the use of an active switching element for coupling laser pulses is unnecessary. The emission of pulses from the solid-state laser can be effected by a coupling-out mirror having a corresponding transmission. The setting of the number of laser pulses emitted by the solid-state laser between two successive pump pulses can be adjusted in particular by the choice of the self-organization time. The longer it is waited for after a pump pulse, the more laser pulses generated by self-organization of the solid-state laser can be emitted, in particular as part of a pulse train or a pulse train. However, it should be noted that an amplitude and a width of the self-organized laser pulses typically decreases with each further laser pulse. Overall, so so pulse trains can be generated with one or more laser pulses. Depending on how many laser pulses such a pulse train or such a pulse sequence should include, then the self-organization time is set larger or smaller. In particular, this can be adjusted by selecting a pump laser repetition rate and a suitable pulse duty factor of the pulsed pump laser radiation.

It is advantageous if the self-organization time t _{self-organization} in a range of about 10 microseconds to about 500 microseconds is specified. In particular, it is advantageous if it is specified in a range from about 10 μs to about 200 μs. Depending on the type of solid-state laser, ie in particular taking into account the active medium, self-organization times for the emission of one or more laser pulses by the solid-state laser can be significantly different.

Preferably, an excitation frequency of the solid-state laser is set in a range of about 1 kHz to about 10 kHz. The excitation frequency of the solid-state laser essentially means the repetition rate with which the Solid-state laser is pumped, ie the number of pump laser pulses per unit time.

An excitation _{pulse duration} t _{pulse duration of} the pump laser radiation is favorably specified in a range from approximately 500 μs to approximately 50 μs. In particular, the excitation pulse duration should be so long that a sufficient number of inverted states can be generated in the active medium of the solid-state laser in order to even achieve the formation of laser pulses by self-organization.

In a particularly simple way, laser pulses can be generated when the solid-state laser is pumped pulse width modulated. In particular, a duty cycle may range from about 0.1 to about 0.5. It is particularly advantageous if the duty ratio is in a range of about 0.15 to 0.3. Taking into account the self-organization time defined above, the duty cycle can then be defined by the ratio of the excitation pulse duration based on the sum of the excitation pulse duration and the self-organization time.

In order to avoid as much as possible energy in the form of laser pulses to the solid-state laser, it is advantageous if the self-assembly time t _{self-organization} is set so that the solid-state laser emitted by self-assembly at least three laser pulses having the first wavelength. It is particularly advantageous if the self-organization time t _{self-organization} is predetermined such that the solid-state laser emits at least five laser pulses by self-organization. For example, with a pulsed pumped Ho: YAG disk laser system, a pulse train with substantially five usable laser pulses can be self-assembled.

According to a further preferred variant, in a method of the type described in the introduction, it can be advantageously provided that the solid-state laser is pumped continuously with the pump laser radiation and that a resonator of the solid-state laser for decoupling a laser pulse of the first wavelength for an opening time t _open from a first state, in that it is closed for the laser radiation of the first wavelength, actively transferred to a second state in which it is open for the laser radiation of the first wavelength. In this way, active laser pulses can be decoupled from the resonator of the solid-state laser. Although this approach has the disadvantage that additional losses must be accepted. However, with this variant of the method according to the invention, the time of emission of a laser pulse and optionally also its intensity and duration can be specified in a more targeted manner.

In a particularly simple way, laser pulses can be decoupled from a resonator of the solid-state laser if an optical decoupling device is used to actively transfer the resonator from the first state to the second state and vice versa. In particular, an optical decoupling device in the form of an acousto-optical or electro-optical modulator can be used or comprise such. This is typically arranged between the resonator defining mirrors.

It is advantageous if the solid-state laser is pumped with the pump laser radiation having the second wavelength in a wavelength range of about 1700 nm to about 2100 nm. For example, with a pump laser radiation in the specified wavelength range, laser pulses having wavelengths in the range of about 2000 nm can be generated. They can be advantageously used in particular for medical applications and material processing.

For medical applications and in material processing, it is advantageous if the laser pulses of the first wavelength are generated with a pulse width in a range from about 0.5 μs to about 3 μs. In particular, it is advantageous if they are generated with a pulse width in a range from about 1.5 μs to about 2.5 μs. In particular, a pulse width can be adjusted by laser pulses generated by self-organization by selecting the laser-active medium and the laser type. In the case of the disk laser, the pulse width also depends on a transmission of the coupling-out mirror.

In a particularly simple and inexpensive way, the solid-state laser can be pumped with a fiber laser or a modulatable diode laser, in particular with a thulium fiber laser.

In order to obtain sufficiently high intensities of the pulsed laser radiation generated by the solid-state laser, it is advantageous if the solid-state laser is pumped with a pump power in a range of about 10 W to about 50 W. By way of the magnitude of the pump power, it is thus also possible to set a pulse energy of the laser pulses generated by self-organization.

According to a further preferred variant of the method according to the invention, it may be provided that pulsed laser radiation having the first wavelength is generated in a wavelength range from about 1800 nm to about 2300 nm. The pulsed laser radiation in this wavelength range can be advantageously used in particular for medical applications as well as for material processing, for example of plastics. In particular, the specified Wavelength range excellent for the structural conversion of powdered kidney and urinary stone crystals through thermal dissolution and shockwave exploitation.

It is advantageous if a disk laser is used as the solid-state laser with a resonator and an active laser medium arranged in the resonator. For example, the active laser medium may be applied directly to a reflective optical element, for example in the form of a disk on a highly reflective mirror. The resonator may further comprise a coupling-out mirror, which has only a low transmittance, in order to enable the coupling out of laser pulses from the solid-state laser resonator.

Advantageously, a Ho-doped medium is used as the active laser medium. In particular, the active medium may be Ho: YAG. Holmium ions in particular allow the generation of laser pulses having a wavelength of about 2100 nm. Preferably, they are pumped with a thulium fiber laser having a second wavelength of about 1900 nm or with a modulatable diode laser.

In order to obtain particularly desired pulse widths in the range of about 0.5 μs to about 3 μs when using a disk laser, it is advantageous if the active laser medium in the form of a disc having a diameter in a range of about 5 mm to about 20 mm used becomes. Further, it is advantageous to use an active lasing medium having a thickness in a range of about 0.1 mm to about 0.5 mm. In particular, a width of the laser pulses generated by self-organization can be approximately adjusted via the thickness of the active laser medium in the disk laser.

The object stated in the introduction is achieved in a system of the type described in the introduction in that the pump laser is a pulse pump for generating pump pulses of the pump laser radiation with a pump pulse interval t _{pump pulse} which corresponds to at least one self-organization time t _{self-organization} in which the solid-state laser at least one self-organization Laser pulse of the first wavelength emitted.

With the system proposed according to the invention, it is in particular possible to decouple laser pulses from the solid-state laser without additional optical element. In this way, an efficiency of the solid-state laser and thus of the system as a whole can be increased. As already explained above in connection with the method proposed according to the invention, in this system the self-organization of laser pulses due to the excitation of the solid-state laser, for example a disk laser, by laser pulses is used to generate one or more laser pulses after excitation with a pump pulse.

It is favorable if the pump pulse distance is in a range from about 10 μs to about 500 μs. Depending on the type of solid-state laser, it is thus possible to generate one or more laser pulses of the first wavelength by self-organization as a result of an excitation pulse.

It is advantageous if a pump laser repetition rate for exciting the solid-state laser is in a range from about 1 kHz to about 10 kHz. In this way, quasi-continuous laser pulses can be generated with a pulse repetition rate which corresponds to the pump laser repetition rate, in particular if a laser pulse of the first wavelength was generated as a result of an excitation pulse.

In order to be able to generate pulses of sufficient power and duration, it is advantageous if an excitation _{pulse duration} t _{pulse duration of} the pump laser radiation lies in a range from approximately 500 μs to approximately 10 μs.

Conveniently, the pump laser is a pulse width modulated pump laser. Preferably, the pump laser is pulse width modulated with a duty cycle in a range of about 0.1 to about 0.5. It is particularly advantageous if the duty cycle is in a range of about 0.15 to about 0.3.

Conveniently, the duty cycle is predetermined so that due to a pump pulse even a self-organized laser pulse is generated or a desired number of laser pulses. It is thus with the application of the laser-active medium with a further pulse at least as long waited until at least one laser pulse has formed by self-organization.

According to a preferred embodiment of the invention, it may be provided that the pump pulse interval t _{pump pulse corresponds to} at least one self-organization time t _{self-organization} , in which the solid-state laser emits at least three laser pulses of the first wavelength by self-organization. In particular, it is favorable if the pump pulse interval t _{pump pulse} is selected so that at least five laser pulses of the first wavelength are emitted. If not only a self-organized laser pulse can be emitted, this increases an output power of the solid-state laser. Thus, in particular, the efficiency of the system can be increased by using several or all self-organized as a result of a pump pulse laser pulses.

Furthermore, it may be advantageous in a system of the type described above, if the solid state laser comprises a resonator when the pump laser is in the form of a continuous wave or cw laser, when the resonator is closed in a first state for the laser radiation of the first wavelength and is open in a second state for the laser radiation of the first wavelength, and if the system for transferring the resonator from the first to the second state and vice versa comprises a switching device with which in particular an opening time t _open for coupling out a laser pulse of the first wavelength is adjustable, for which opening time the resonator assumes the second state.

In particular, such a system makes it possible to actively decouple pulses from the resonator of the solid-state laser. This makes it particularly easy to set a time for the emission of the laser pulse from the system.

It is advantageous if the switching device comprises an optical coupling-out device. Preferably, the optical outcoupling device in the form of an acousto-optical or an electro-optical modulator is formed or includes such.

Conveniently, the pump laser radiation has a wavelength in a wavelength range of about 1700 nm to about 2100 nm. A pump laser, which emits pump laser radiation in the specified wavelength range, is outstandingly suitable for pumping solid-state lasers which emit laser pulses in a wavelength range from about 2000 nm to about 2200 nm.

It is advantageous if the laser pulses of the first wavelength emitted by the system have a pulse width in a range from about 0.5 μs to about 3 μs. In particular, it is favorable if a pulse width is in a range of about 1.5 μs to about 2.5 μs. For example, the pulse width of the laser pulses generated by the system by the active medium of the solid-state laser and / or by the laser type can be specified. In particular, pulse widths of bar lasers and disk lasers differed. In particular, pulse widths in the range of about 2 μs are outstandingly suitable for medical applications, for example for use in a laser lithotripter.

A solid-state laser can be pumped in a simple manner if the pump laser is designed in the form of a fiber laser or a modulatable diode laser. In particular, it is advantageous if the fiber laser is designed in the form of a thulium fiber laser. For example, a thulium fiber laser is particularly well suited for pumping holmium as the active material.

In order to be able to vary the power of the laser pulses of the first wavelength, it is favorable for the pump power of the pump laser to be in a range from approximately 10 W to approximately 500 W.

Advantageously, the first wavelength of the pulsed laser radiation is in a wavelength range of about 1800 nm to about 2300 nm. Laser pulses having a wavelength in the specified wavelength range are particularly well suited for medical applications.

According to a further preferred embodiment of the invention, it can be provided that the solid-state laser is designed in the form of a disk laser with a resonator and an active laser medium arranged in the resonator. In particular, the active laser medium can be arranged on one of two reflective optical elements which define the resonator. Ideally, a reflective optical instrument, for example in the form of a mirror, is opaque and fully reflective for first wavelength light, but another mirror is only approximately 100% reflective. For example, the second mirror may be in the form of a decoupling mirror with a transmittance of less than 5%, favorably less than 1%.

It is advantageous if a Ho-doped medium is used as the active laser medium. In particular, the active laser medium can be Ho: YAG. With such an active material, Ho ions, namely Ho ³⁺ , form the actually active material which has been introduced by doping into an yttrium-aluminum-garnet crystal.

Preferably, the active laser medium is in the form of a disc having a diameter in a range of about 5 mm to about 20 mm. Furthermore, it may be advantageous if a thickness of the active laser medium is in a range of about 0.1 mm to about 0.5 mm. For example, in the case of the disk laser, parameters of the pulses generated can be predetermined over a thickness of the disk.

The object stated at the outset is also achieved in a material processing system, in particular for processing plastics, comprising a pulsed laser radiation emitting system according to the invention that the pulsed laser radiation emitting system is formed in the form of one of the advantageous systems described above. With such a material processing system, for example, plastics can be exposed to the generated laser pulses of the first wavelength in order, in particular, to process a surface.

The object stated in the introduction is also achieved with a medical device, in particular in the form of a laser lithotripter for the thermal treatment of kidney and ureteral stones, if it comprises one of the above-described advantageous systems for generating laser pulses. In particular, a system with a Ho: YAG disk laser makes it possible to generate pulses with a wavelength of about 2100 nm and a pulse width of about 2 μs. Such pulses are very well suited to pulverize kidneys or urinary stones under thermal dissolution.

Furthermore, the use of one of the above-described systems for material processing is proposed, in particular for plastics processing.

• 1. Verfahren zur Erzeugung gepulster Laserstrahlung (44; 44') einer ersten Wellenlänge, bei welchem ein Festkörperlaser (16; 16') mit Pumplaserstrahlung (14; 14') einer zweiten Wellenlänge gepumpt wird, dadurch gekennzeichnet, dass der Festkörperlaser (16') mit Pumppulsen (52) der Pumplaserstrahlung (14') gepulst gepumpt wird und dass eine Selbstorganisationszeit t_{Selbstorganisation} des Festkörperlasers (16') zwischen zwei aufeinanderfolgenden Pumppulsen (52) so vorgegeben wird, dass der Festkörperlaser (16') durch Selbstorganisation mindestens einen Laserpuls (58a, 58b, 58c, 58d, 58e) erster Wellenlänge emittiert.
• 2. Vorrichtung nach Satz 1, dadurch gekennzeichnet, dass die Selbstorganisationszeit t_{Selbstorganisation} in einem Bereich von etwa 5 μs bis etwa 500 μs vorgegeben wird, insbesondere in einem Bereich von etwa 10 μs bis etwa 200 μs.
• 3. Verfahren nach Satz 1 oder 2, dadurch gekennzeichnet, dass eine Anregungsfrequenz des Festkörperlasers (16') in einem Bereich von etwa 1 kHz bis etwa 10 kHz vorgegeben wird.
• 4. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass eine Anregungspulsdauer t_Pulsdauer der Pumplaserstrahlung (14') in einem Bereich von etwa 500 μs bis etwa 50 μs vorgegeben wird.
• 5. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass der Festkörperlaser (16') pulsweitenmoduliert gepumpt wird, insbesondere mit einem Tastverhältnis in einem Bereich von etwa 0,1 bis etwa 0,5, weiter insbesondere in einem Bereich von etwa 0,15 bis etwa 0,3.
• 6. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass die Selbstorganisationszeit t_{Selbstorganisation} so vorgegeben wird, dass der Festkörperlaser (16') durch Selbstorganisation mindestens drei Laserpulse (58a, 58b, 58c, 58d, 58e) erster Wellenlänge emittiert, insbesondere fünf Laserpulse (58a, 58b, 58c, 58d, 58e).
• 7. Verfahren nach dem Oberbegriff des Satzes 1, dadurch gekennzeichnet, dass der Festkörperlaser (16) mit der Pumplaserstrahlung (14) kontinuierlich gepumpt wird und dass ein Resonator (36) des Festkörperlasers zum Auskoppeln eines Laserpulses (46) der ersten Wellenlänge für eine Öffnungszeit t_offen von einem ersten Zustand, in dem er für die Laserstrahlung (44) der ersten Wellenlänge geschlossen ist, aktiv in einen zweiten Zustand, in dem er für die Laserstrahlung (44) der ersten Wellenlänge geöffnet ist, überführt wird.
• 8. Verfahren nach Satz 7, dadurch gekennzeichnet, dass zum aktiven Überführen des Resonators (36) vom ersten Zustand in den zweiten Zustand und umgekehrt eine optische Auskoppeleinrichtung (70) verwendet wird, insbesondere ein akusto-optischer oder ein elektro-optischer Modulator (40).
• 9. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass der Festkörperlaser (16; 16') mit der Pumplaserstrahlung (14; 14') mit der zweiten Wellenlänge in einem Wellenlängenbereich von etwa 1700 nm bis etwa 2100 nm gepumpt wird.
• 10. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass die Laserpulse (46; 58a, 58b, 58c, 58d, 58e) der ersten Wellenlänge mit einer Pulsbreite in einem Bereich von etwa 0,5 μs bis etwa 3 μs erzeugt werden, insbesondere in einem Bereich von etwa 1,5 μs bis etwa 2,5 μs.
• 11. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass der Festkörperlaser (16; 16') mit einem Faserlaser (72; 72') oder einem modulierbaren Diodenlaser gepumpt wird, insbesondere mit einem Thulium-Faserlaser (74; 74').
• 12. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass der Festkörperlaser (16; 16') mit einer Pumpleistung in einem Bereich von etwa 10 W bis etwa 500 W gepumpt wird.
• 13. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass gepulste Laserstrahlung (44; 44') mit der ersten Wellenlänge in einem Wellenlängenbereich von etwa 1800 nm bis etwa 2300 nm erzeugt wird.
• 14. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass als Festkörperlaser (16; 16') ein Scheibenlaser (18; 18') verwendet wird mit einem Resonator (36; 36') und einem im Resonator (36; 36') angeordneten aktiven Lasermedium (28; 28').
• 15. Verfahren nach Satz 14, dadurch gekennzeichnet, dass als aktives Lasermedium (28; 28') ein Ho-dotiertes Medium verwendet wird, insbesondere Ho:YAG.
• 16. Verfahren nach Satz 14 oder 15, dadurch gekennzeichnet, dass das aktive Lasermedium (28; 28') in Form einer Scheibe (30; 30') mit einem Durchmesser in einem Bereich von etwa 5 mm bis etwa 20 mm und/oder mit einer Dicke in einem Bereich von etwa 0,1 mm bis etwa 0,5 mm verwendet wird.
• 17. System (10; 10') zur Erzeugung gepulster Laserstrahlung (44; 44') einer ersten Wellenlänge, umfassend einen Pumplaser (12; 12') und einen mit dem Pumplaser (12; 12') gepumpten Festkörperlaser (16; 16'), welcher Pumplaser (12; 12') Pumplaserstrahlung (14; 14') einer zweiten Wellenlänge erzeugt, dadurch gekennzeichnet, dass der Pumplaser (12') ein Pulspumplaser (12') ist zum Erzeugen von Pumppulsen (52) der Pumplaserstrahlung (14) mit einem Pumppulsabstand t_Pumppuls, welcher mindestens einer Selbstorganisationszeit t_{Selbstorganisation} entspricht, in welcher der Festkörperlaser (14') durch Selbstorganisation mindestens einen Laserpuls (58a, 58b, 58c, 58d, 58e) erster Wellenlänge emittiert.
• 18. System nach Satz 17, dadurch gekennzeichnet, dass der Pumppulsabstand (56) in einem Bereich von etwa 10 μs bis etwa 500 μs liegt.
• 19. System nach Satz 17 oder 18, dadurch gekennzeichnet, dass eine Pumplaserrepetitionsrate zum Anregen des Festkörperlasers (16') in einem Bereich von etwa 1 kHz bis etwa 10 kHz liegt.
• 20. System nach einem der Sätze 17 bis 19, dadurch gekennzeichnet, dass eine Anregungspulsdauer t_Pulsdauer der Pumplaserstrahlung (14') in einem Bereich von etwa 500 μs bis etwa 10 μs.
• 21. System nach einem der Sätze 17 bis 20, dadurch gekennzeichnet, dass der Pumplaser (12') ein pulsweitenmodulierter Pumplaser (12') ist, insbesondere mit einem Tastverhältnis in einem Bereich von etwa 0,1 bis etwa 0,5, weiter insbesondere in einem Bereich von etwa 0,15 bis etwa 0,3.
• 22. System nach einem der Sätze 17 bis 21, dadurch gekennzeichnet, dass der Pumppulsabstand t_Pumppuls mindestens einer Selbstorganisationszeit t_{Selbstorganisation} entspricht, in welcher der Festkörperlaser (16') durch Selbstorganisation mindestens drei Laserpulse (58a, 58b, 58c, 58d, 58e) erster Wellenlänge emittiert, insbesondere fünf Laserpulse (58a, 58b, 58c, 58d, 58e).
• 23. System nach dem Oberbegriff des Satzes 17, dadurch gekennzeichnet, dass der Festkörperlaser (16) einen Resonator (36) umfasst, dass der Pumplaser (12) in Form eines Dauerstrich- oder cw-Lasers ausgebildet ist, dass der Resonator (36) in einem ersten Zustand für die Laserstrahlung (44) der ersten Wellenlänge geschlossen ist und in einem zweiten Zustand für die Laserstrahlung (44) der ersten Wellenlänge geöffnet ist und dass das System (10) zum Überführen des Resonators (36) vom ersten in den zweiten Zustand und umgekehrt eine Schalteinrichtung (38) umfasst, mit welcher insbesondere eine Öffnungszeit t_offen zum Auskoppeln eines Laserpulses (46) der ersten Wellenlänge einstellbar ist, für welche Öffnungszeit der Resonator (36) den zweiten Zustand einnimmt.
• 24. System nach Satz 23, dadurch gekennzeichnet, dass die Schalteinrichtung eine optische Auskoppeleinrichtung (70) umfasst, insbesondere einen akusto-optischen oder einen elektro-optischen Modulator (40).
• 25. System nach einem der Sätze 17 bis 24, dadurch gekennzeichnet, dass die Pumplaserstrahlung (14) eine Wellenlänge in einem Wellenlängenbereich von etwa 1700 nm bis etwa 2100 nm aufweist.
• 26. System nach einem der Sätze 17 bis 25, dadurch gekennzeichnet, dass die Laserpulse (46; 58a, 58b, 58c, 58d, 58e) der ersten Wellenlänge eine Pulsbreite (50; 64) in einem Bereich von etwa 0,5 μs bis etwa 3 μs aufweisen, insbesondere in einem Bereich von etwa 1,5 μs bis etwa 2,5 μs.
• 27. System nach einem der Sätze 17 bis 26, dadurch gekennzeichnet, dass der Pumplaser (12; 12') in Form eines Faserlasers (72; 72') oder eines modulierbaren Diodenlasers ausgebildet ist, insbesondere in Form eines Thulium-Faserlasers (74; 74').
• 28. System nach einem der Sätze 17 bis 27, dadurch gekennzeichnet, dass eine Pumpleistung des Pumplasers (12; 12') in einem Bereich von etwa 10 W bis etwa 500 W liegt.
• 29. System nach einem der Sätze 17 bis 28, dadurch gekennzeichnet, dass die erste Wellenlänge der gepulsten Laserstrahlung (44; 44') in einem Wellenlängenbereich von etwa 1800 nm bis etwa 2300 nm liegt.
• 30. System nach einem der Sätze 17 bis 29, dadurch gekennzeichnet, dass der Festkörperlaser (16; 16') in Form eines Scheibenlasers (18; 18') ausgebildet ist mit einem Resonator (36; 36') und einem im Resonator (36; 36') angeordneten aktiven Lasermedium (28; 28').
• 31. System nach Satz 30, dadurch gekennzeichnet, dass als aktives Lasermedium (28; 28') ein Ho-dotiertes Medium verwendet wird, insbesondere Ho:YAG.
• 32. System nach Satz 30 oder 31, dadurch gekennzeichnet, dass das aktive Lasermedium (28; 28') in Form einer Scheibe (30; 30') mit einem Durchmesser in einem Bereich von etwa 5 mm bis etwa 20 mm aufweist und/ oder eine Dicke in einem Bereich von etwa 0,1 mm bis etwa 0,5 mm.
• 33. Materialbearbeitungssystem, insbesondere zur Bearbeitung von Kunststoffen, umfassend ein gepulste Laserstrahlung (44; 44') emittierendes System (10; 10'), dadurch gekennzeichnet, dass das gepulste Laserstrahlung emittierende System (10; 10') in Form eines der Systeme (10; 10') nach einem der Sätze 17 bis 32 ausgebildet ist.
• 34. Medizinisches Gerät (66), insbesondere in Form eines Laser-Lithotripters (68) für die thermische Behandlung von Nieren- und Harnleitersteinen, gekennzeichnet durch ein System (10; 10') nach einem der Sätze 17 bis 32.
• 35. Verwendung eines Systems (10; 10') nach einem der Sätze 17 bis 32 zur Materialbearbeitung, insbesondere zur Kunststoffbearbeitung.

The above description thus includes in particular the embodiments of methods and systems for generating pulsed laser radiation, material processing systems, medical devices and uses of systems for generating pulsed laser radiation, which are defined below in the form of numbered sets:

• 1. A method for generating pulsed laser radiation ( 44 ; 44 ' ) of a first wavelength at which a solid-state laser ( 16 ; 16 ' ) with pump laser radiation ( 14 ; 14 ' ) is pumped at a second wavelength, characterized in that the solid-state laser ( 16 ' ) with pump pulses ( 52 ) of the pump laser radiation ( 14 ' ) is pumped in a pulsed manner and that a self-organization time t _{self-organization of} the solid-state laser ( 16 ' ) between two successive pump pulses ( 52 ) is specified so that the solid-state laser ( 16 ' ) by self-organization at least one laser pulse ( 58a . 58b . 58c . 58d . 58e ) first wavelength emitted.
• 2. Device according to sentence 1, characterized in that the self-organization time t _{self-organization} in a range of about 5 microseconds to about 500 microseconds is specified, in particular in a range of about 10 microseconds to about 200 microseconds.
• 3. Method according to sentence 1 or 2, characterized in that an excitation frequency of the solid-state laser ( 16 ' ) is set in a range of about 1 kHz to about 10 kHz.
• 4. Device according to one of the preceding sentences, characterized in that an excitation _{pulse duration} t _{pulse duration of} the pump laser radiation ( 14 ' ) is set in a range of about 500 μs to about 50 μs.
• 5. Method according to one of the preceding sentences, characterized in that the solid-state laser ( 16 ' ) is pulse-width modulated pumped, in particular with a duty cycle in a range of about 0.1 to about 0.5, more particularly in a range of about 0.15 to about 0.3.
• 6. The method according to one of the preceding sentences, characterized in that the self-organization time t _{self-organization} is specified so that the solid-state laser (1 6 ' ) by self-organization at least three laser pulses ( 58a . 58b . 58c . 58d . 58e ) first wavelength, in particular five laser pulses ( 58a . 58b . 58c . 58d . 58e ).
• 7. Method according to the preamble of sentence 1, characterized in that the solid-state laser ( 16 ) with the pump laser radiation ( 14 ) is continuously pumped and that a resonator ( 36 ) of the solid-state laser for decoupling a laser pulse ( 46 ) of the first wavelength for an opening time t _open from a first state in which it is used for the laser radiation ( 44 ) of the first wavelength is active, active in a second state in which it for the laser radiation ( 44 ) of the first wavelength is opened, is transferred.
• 8. Method according to sentence 7, characterized in that for actively transferring the resonator ( 36 ) from the first state to the second state and, conversely, an optical output device ( 70 ), in particular an acousto-optical or an electro-optical modulator ( 40 ).
• 9. Method according to one of the preceding sentences, characterized in that the solid-state laser ( 16 ; 16 ' ) with the pump laser radiation ( 14 ; 14 ' ) at the second wavelength in a wavelength range of about 1700 nm to about 2100 nm.
• 10. Device according to one of the preceding sentences, characterized in that the laser pulses ( 46 ; 58a . 58b . 58c . 58d . 58e ) of the first wavelength having a pulse width in a range of about 0.5 μs to about 3 μs, in particular in a range of about 1.5 μs to about 2.5 μs.
• 11. Method according to one of the preceding sentences, characterized in that the solid-state laser ( 16 ; 16 ' ) with a fiber laser ( 72 ; 72 ' ) or a modulatable diode laser, in particular with a thulium fiber laser ( 74 ; 74 ' ).
• 12. Method according to one of the preceding sentences, characterized in that the solid-state laser ( 16 ; 16 ' ) is pumped at a pump power in a range of about 10 W to about 500 W.
• 13. Method according to one of the preceding sentences, characterized in that pulsed laser radiation ( 44 ; 44 ' ) at the first wavelength in a wavelength range of about 1800 nm to about 2300 nm.
• 14. Method according to one of the preceding sentences, characterized in that as solid state laser ( 16 ; 16 ' ) a disk laser ( 18 ; 18 ' ) is used with a resonator ( 36 ; 36 ' ) and one in the resonator ( 36 ; 36 ' ) arranged active laser medium ( 28 ; 28 ' ).
• 15. Method according to sentence 14, characterized in that as the active laser medium ( 28 ; 28 ' ) a Ho-doped medium is used, in particular Ho: YAG.
• 16. Method according to sentence 14 or 15, characterized in that the active laser medium ( 28 ; 28 ' ) in the form of a disk ( 30 ; 30 ' ) having a diameter in a range of about 5 mm to about 20 mm and / or having a thickness in a range of about 0.1 mm to about 0.5 mm.
• 17. System ( 10 ; 10 ' ) for generating pulsed laser radiation ( 44 ; 44 ' ) of a first wavelength, comprising a pump laser ( 12 ; 12 ' ) and one with the pump laser ( 12 ; 12 ' ) pumped solid-state lasers ( 16 ; 16 ' ), which pump laser ( 12 ; 12 ' ) Pump laser radiation ( 14 ; 14 ' ) of a second wavelength, characterized in that the pump laser ( 12 ' ) a pulse pump laser ( 12 ' ) is for generating pump pulses ( 52 ) of the pump laser radiation ( 14 ) with a pump pulse interval t _{pump pulse} , which corresponds to at least one self-organization time t _{self-organization} , in which the solid-state laser ( 14 ' ) by self-organization at least one laser pulse ( 58a . 58b . 58c . 58d . 58e ) first wavelength emitted.
• 18. System according to sentence 17, characterized in that the pump pulse distance ( 56 ) is in a range of about 10 μs to about 500 μs.
• 19. System according to sentence 17 or 18, characterized in that a pump laser repetition rate for exciting the solid-state laser ( 16 ' ) is in a range of about 1 kHz to about 10 kHz.
• 20. System according to one of the sentences 17 to 19, characterized in that an excitation _{pulse duration} t _{pulse duration of} the pump laser radiation ( 14 ' ) in a range of about 500 μs to about 10 μs.
• 21. System according to one of the sentences 17 to 20, characterized in that the pump laser ( 12 ' ) a pulse width modulated pump laser ( 12 ' ), in particular with a duty cycle in a range of about 0.1 to about 0.5, more particularly in a range of about 0.15 to about 0.3.
• 22. System according to one of the sentences 17 to 21, characterized in that the pump pulse interval t _{pump pulse corresponds to} at least one self-organization time t _{self-organization} , in which the solid-state laser ( 16 ' ) by self-organization at least three laser pulses ( 58a . 58b . 58c . 58d . 58e ) first wavelength, in particular five laser pulses ( 58a . 58b . 58c . 58d . 58e ).
• 23. System according to the preamble of the sentence 17, characterized in that the solid-state laser ( 16 ) a resonator ( 36 ), that the pump laser ( 12 ) is designed in the form of a continuous wave or cw laser, that the resonator ( 36 ) in a first state for the laser radiation ( 44 ) of the first wavelength is closed and in a second state for the laser radiation ( 44 ) of the first wavelength is open and that the system ( 10 ) for transferring the resonator ( 36 ) from the first to the second state and vice versa a switching device ( 38 ) Includes, with which in particular an opening time t _open for coupling out a laser pulse ( 46 ) of the first wavelength is adjustable, for which opening time the resonator ( 36 ) assumes the second state.
• 24. System according to sentence 23, characterized in that the switching device is an optical output device ( 70 ), in particular an acousto-optical or an electro-optical modulator ( 40 ).
• 25. System according to one of the sentences 17 to 24, characterized in that the pump laser radiation ( 14 ) has a wavelength in a wavelength range of about 1700 nm to about 2100 nm.
• 26. System according to one of the sentences 17 to 25, characterized in that the laser pulses ( 46 ; 58a . 58b . 58c . 58d . 58e ) of the first wavelength a pulse width ( 50 ; 64 ) in a range from about 0.5 μs to about 3 μs, in particular in a range from about 1.5 μs to about 2.5 μs.
• 27. System according to one of the sentences 17 to 26, characterized in that the pump laser ( 12 ; 12 ' ) in the form of a fiber laser ( 72 ; 72 ' ) or a modulatable diode laser, in particular in the form of a thulium fiber laser ( 74 ; 74 ' ).
• 28. System according to one of the sentences 17 to 27, characterized in that a pumping power of the pump laser ( 12 ; 12 ' ) is in a range of about 10 W to about 500 W.
• 29. System according to one of the sentences 17 to 28, characterized in that the first wavelength of the pulsed laser radiation ( 44 ; 44 ' ) is in a wavelength range of about 1800 nm to about 2300 nm.
• 30. System according to one of the sentences 17 to 29, characterized in that the solid-state laser ( 16 ; 16 ' ) in the form of a disk laser ( 18 ; 18 ' ) is formed with a resonator ( 36 ; 36 ' ) and one in the resonator ( 36 ; 36 ' ) arranged active laser medium ( 28 ; 28 ' ).
• 31. System according to sentence 30, characterized in that as an active laser medium ( 28 ; 28 ' ) a Ho-doped medium is used, in particular Ho: YAG.
• 32. System according to sentence 30 or 31, characterized in that the active laser medium ( 28 ; 28 ' ) in the form of a disk ( 30 ; 30 ' ) having a diameter in a range of about 5 mm to about 20 mm and / or a thickness in a range of about 0.1 mm to about 0.5 mm.
• 33. Material processing system, in particular for processing plastics, comprising a pulsed laser radiation ( 44 ; 44 ' ) emitting System ( 10 ; 10 ' ), characterized in that the pulsed laser radiation emitting system ( 10 ; 10 ' ) in the form of one of the systems ( 10 ; 10 ' ) is formed according to one of the sentences 17 to 32.
• 34. Medical device ( 66 ), in particular in the form of a laser lithotripter ( 68 ) for the thermal treatment of kidney and ureteral stones, characterized by a system ( 10 ; 10 ' ) according to one of the sentences 17 to 32.
• 35. Use of a system ( 10 ; 10 ' ) according to one of the sentences 17 to 32 for material processing, in particular for plastics processing.

The following description of preferred embodiments of the invention is used in conjunction with the drawings for further explanation. Show it:

1 a schematic representation of a first embodiment of a system for generating pulsed laser radiation;

2 : an oscilloscope recording of a with the in 1 shown system generated laser pulses;

3 a schematic arrangement of a second embodiment of a system for generating pulsed laser radiation;

4 : an oscilloscope shot of by self-organization with the in 3 illustrated system generated laser pulses;

5 : a representation of the calculated dependence of an inversion of the laser system as a function of time for self-organizing laser pulses on the basis of the rate equations of the laser;

6 : a theoretically calculated dependence of the laser intensity as a function of time for self-organizing laser pulses on the basis of the rate equations of the laser;

7 FIG. 2: a graph of the output power of the solid-state laser as a function of the pump power; FIG.

8th : a comparison of the energy of laser pulses of the first wavelength as a function of the pump power; and

9 : A schematic representation of a medical device comprising a system for generating pulsed laser radiation.

In 1 schematically is a first embodiment of a system 10 shown schematically for generating laser pulses. It includes a pump laser 12 , For example, a fiber laser 72 in the form of a thulium fiber laser 77 or a modulatable diode laser for generating a pump laser radiation 14 , with which a solid-state laser 16 in the form of a disk laser 18 is pumped.

The disk laser 18 includes a disk laser module 20 , with an entrance opening 22 for the pump laser radiation 14 and an exit opening 24 for the laser pulses to be generated.

In the disk laser module 20 is on a mirror 26 a laser-active medium 28 in the form of a slices 30 arranged. Furthermore, the disk laser module comprises 20 several mirrors 32 that the pump laser radiation 14 several times on the disc 30 image, so that the pump laser radiation 14 the disc 30 repeatedly irradiated.

The solid-state laser 16 further comprises a second mirror 34 , which together with the mirror 26 a resonator 36 of the solid-state laser 16 Are defined. In the resonator 36 is a decoupling device 70 comprising a switching device 38 , for example in the form of an electro-optical or electro-acoustic modulator 40 or a Pockels cell arranged. Between the switching device 38 and the disk laser module 20 is a polarizer 42 arranged, with which a part of the solid-state laser 16 generated radiation 44 is disengageable to the switching device 38 head for.

The pump laser 12 will be at the in 1 shown arrangement preferably operated in cw mode.

To a laser pulse 46 from the resonator 36 decouple, the resonator of the cw-pumped solid-state laser 16 briefly opened, by the switching device 38 that the resonator 36 from a first state in which he is responsible for the laser radiation 44 is closed, transferred to a second state, in which he is responsible for the laser radiation 44 is open. In the second state, then a laser pulse 46 the resonator 36 through the mirror 34 , also referred to as Auskoppelspiegel, leave.

In 2 For example, an oscilloscope image is shown, which has a control edge at the top 48 shows which the switching device 38 activates to transfer the resonator 36 from the first state to the second state. The below shown, actively decoupled single laser pulse 46 has a pulse width 50 of about 1 μs.

At the in 1 schematically illustrated system 10 is called a laser-active medium 28 a disk 30 from Ho-doped YAG, ie a Ho: YAG disk laser 18 ,

Through the use of the switching device 38 at the system 10 becomes an efficiency of the system 10 reduced due to unavoidable losses.

To the efficiency and efficiency of the system 10 can be further developed and operated in a slightly modified form.

3 schematically shows the structure of a second embodiment of a system 10 ' for generating laser pulses. Identical elements are provided with identical reference numerals and supplemented by a coat "'".

The pump laser 12 ' For example, a fiber laser 72 ' in the form of a thulium fiber laser 74 ' or a modulatable diode laser, is used in the system 10 but not operated in cw mode, but pulsed, in particular pulse width modulated. The pump laser radiation 14 ' is through the entrance opening 22 ' of the disk laser module 20 ' coupled and on the active medium 28 ' in the form of the disc 30 ' displayed. The mirror 32 ' in conjunction with the mirror 26 ' the one together with the mirror 34 ' the resonator 36 ' defined, allows the multiple transmission of the disc 30 ' with the pump laser radiation 14 ' ,

The system 10 ' However, does not include a switching device for coupling out pulses. This is not necessary because of the pulsed pumping of the solid-state laser 16 ' by self-organization laser pulses 58a . 58b . 58c . 58d and 58e generated by the partially transmissive mirror 34 ' the resonator 36 ' being able to leave.

4 shows an example of an oscilloscope image, in which above the time course of the pump laser radiation 14 ' is shown. This is formed by individual, rectangular pump pulses 52 , These have a width of about 100 μs on. A distance between two pump pulses 52 , also as a self-organization time 56 denotes, amounts to 4 about 400 μs. This is a duty cycle of the pulse width modulated pump radiation 14 ' about 1: 5.

The system 10 ' makes the effect of the self-organization of laser pulses in a disk laser 18 ' exploited when it is pulsed pumped. A first laser pulse 58a of a five laser pulses 58a . 58b . 58c . 58d and 58e comprehensive pulse train 60 , also referred to as pulse sequence, becomes after a delay time 62 a little more than 100 μs after the falling edge of the pump laser pulse 52 from the system 10 ' emitted. The laser pulses 58b . 58c . 58d and 58e follow the first laser pulse 58a with approximately equal intervals of approximately 60 μs each. A maximum intensity of the successive laser pulses 58a . 58b . 58c . 58d and 58e decreases gradually.

The in 4 shown, measured course of intensity of the out of the system 10 ' emitted laser pulses 58a . 58b . 58c . 58d and 58e is theoretically assignable. In 5 is that by solving the rate equations of the solid-state laser 16 ' calculated inversion of the disk laser 18 ' shown as a function of time.

From the in 5 shown inversion then results arithmetically in 6 shown pulse sequence 60 , that is, the intensity of the laser pulses generated by self-organization as a function of time. Here is good to see that an intensity of successive pulses 58 as a function of time decreases approximately exponentially, with a distance of the laser pulses remains approximately the same.

By choosing the active medium 28 respectively 28 ' may be the wavelength of the emitted laser pulses 46 respectively 58 be specified. This is about 2100 nm in a Ho: YAG system.

In 7 is the dependence of the output power of the systems 10 and 10 ' shown. The cw-pumped system 10 has a little higher output power than the PWM-modulated pumped system 10 ' ,

However, the efficiency of the system is surprising 10 ' compared to the system 10 , This is schematically in 8th shown. The middle curve shows the energy of the laser pulses 46 of the system 10 depending on the pump power.

The lower curve in 8th shows the energy of the laser pulse 58a of the system 10 ' , that is, the first laser pulse generated by self-organization 58a ,

In contrast, the energy of the five laser pulses exceeds 58 comprehensive pulse train 60 the energy of the system 10 generated individual pulses 46 by significantly more than the factor 2. In other words, although the energy of a single laser pulse 58a , also referred to as a single pulse, which is generated by self-organization, smaller than an energy of the laser pulse 46 , by means of the switching device 38 with the system 10 is produced. However, with proper choice of self-organization time 56 be achieved that the system 10 ' two or more laser pulses 58 generated, which then in sum have a pulse energy which is at least about the pulse energy of the system 10 generated single laser pulse 46 is. Use the pulse train 60 completely or almost completely by the self-organization time 56 is selected accordingly long, then it is possible with the system 10 ' close to the cw output of the disk laser 16 ' to come from 100%.

The systems 10 and 10 ' can be used in a variety of ways. For example, they can be used for material processing as part of material processing systems, in particular for processing plastics, for example from their surfaces.

As in 9 Schematically illustrated, but is also the use of the systems 10 and 10 ' as part of a medical device 66 , in particular in the form of a laser lithotripter 68 for the thermal treatment of renal and ureteral systems, is possible in an advantageous manner. In particular, the system 10 ' makes it possible to generate high pulse energies in order to gently pulverize kidney or ureteral stones by thermal treatment.

As already described above, the intensity of the laser pulses can be adjusted 46 and 58a . 58b . 58c . 58d and 58e by the pumping power of the pump laser 12 relationship meadow 12 ' influence. One pulse width 64 the one from the system 10 ' generated laser pulses 58 depends in particular on the selected laser-active medium 28 respectively 28 ' but also on the type of solid-state laser used 16 and 16 ' , For the exemplary presented Ho: YAG system is the pulse width 64 about 2 μs.

LIST OF REFERENCE NUMBERS

10; 10 '

 system

12; 12 '

 pump laser

14; 14 '

 Pump laser radiation

16; 16 '

 Solid-state lasers

18; 18 '

 disk laser

20; 20 '

 Disk laser module

22; 22 '

 inlet opening

24; 24 '

 outlet opening

26; 26 '

 mirror

28; 28 '

 active medium

30; 30 '

 disc

32; 32 '

 mirror

34; 34 '

mirror

36; 36 '

 resonator

38

 switching device

40

 modulator

42

 polarizer

44; 44 '

 radiation

46

 laser pulse

48

 control flank

50

 pulse width

52

 pump pulse

54

 pulse width

56

 Self-organization time

58a, 58b, 58c, 58d, 58e

 laser pulse

60

 pulse train

62

 Delay Time

64

 pulse width

66

 medical device

68

 Laser lithotripter

70

 decoupling

72; 72 '

 fiber laser

74; 74 '

 Thulium fiber laser

Claims (20)

Method for generating pulsed laser radiation ( 44 ; 44 ' ) of a first wavelength at which a solid-state laser ( 16 ; 16 ' ) with pump laser radiation ( 14 ; 14 ' ) is pumped at a second wavelength, characterized in that the solid-state laser ( 16 ' ) with pump pulses ( 52 ) of the pump laser radiation ( 14 ' ) is pumped in a pulsed manner and that a self-organization time t _{self-organization of} the solid-state laser ( 16 ' ) between two successive pump pulses ( 52 ) is specified so that the solid-state laser ( 16 ' ) by self-organization at least one laser pulse ( 58a . 58b . 58c . 58d . 58e ) first wavelength emitted. Apparatus according to claim 1, characterized in that the self-organization time t _{self-organization} in a range of about 5 microseconds to about 500 μs is specified, in particular in a range of about 10 microseconds to about 200 μs, and / or that an excitation frequency of the solid-state laser ( 16 ' ) is set in a range of about 1 kHz to about 10 kHz. Device according to one of the preceding claims, characterized in that an excitation _{pulse duration} t _{pulse duration of} the pump laser radiation ( 14 ' ) in a range from about 500 μs to about 50 μs and / or that the solid state laser ( 16 ' ) is pulse-width modulated pumped, in particular with a duty cycle in a range of about 0.1 to about 0.5, more particularly in a range of about 0.15 to about 0.3. Method according to one of the preceding claims, characterized in that the self-organization time t _{self-organization} is specified so that the solid-state laser ( 16 ' ) by self-organization at least three laser pulses ( 58a . 58b . 58c . 58d . 58e ) first wavelength, in particular five laser pulses ( 58a . 58b . 58c . 58d . 58e ). Method according to the preamble of claim 1, characterized in that the solid state laser ( 16 ) with the pump laser radiation ( 14 ) is continuously pumped and that a resonator ( 36 ) of the solid-state laser for decoupling a laser pulse ( 46 ) of the first wavelength for an opening time t _open from a first state in which it is used for the laser radiation ( 44 ) of the first wavelength is closed is active in a second state in which he is responsible for the laser radiation ( 44 ) of the first wavelength is opened, is transferred. Method according to one of the preceding claims, characterized in that the solid-state laser ( 16 ; 16 ' ) with the pump laser radiation ( 14 ; 14 ' ) is pumped at the second wavelength in a wavelength range of about 1700 nm to about 2100 nm and / or that the laser pulses ( 46 ; 58a . 58b . 58c . 58d . 58e ) of the first wavelength having a pulse width in a range of about 0.5 μs to about 3 μs, in particular in a range of about 1.5 μs to about 2.5 μs and / or that the solid-state laser ( 16 ; 16 ' ) with a fiber laser ( 72 ; 72 ' ) or a modulatable diode laser, in particular with a thulium fiber laser ( 74 ; 74 ' ). Method according to one of the preceding claims, characterized in that the solid-state laser ( 16 ; 16 ' ) is pumped at a pump power in a range of about 10 W to about 500 W and / or that pulsed laser radiation ( 44 ; 44 ' ) is generated with the first wavelength in a wavelength range of about 1800 nm to about 2300 nm and / or that as a solid state laser ( 16 ; 16 ' ) a disk laser ( 18 ; 18 ' ) is used with a resonator ( 36 ; 36 ' ) and one in the resonator ( 36 ; 36 ' ) arranged active laser medium ( 28 ; 28 ' ). Method according to claim 7, characterized in that as an active laser medium ( 28 ; 28 ' ) a Ho-doped medium is used, in particular Ho: YAG, and / or that the active laser medium ( 28 ; 28 ' ) in the form of a disk ( 30 ; 30 ' ) having a diameter in a range of about 5 mm to about 20 mm and / or having a thickness in a range of about 0.1 mm to about 0.5 mm. System ( 10 ; 10 ' ) for generating pulsed laser radiation ( 44 ; 44 ' ) of a first wavelength, comprising a pump laser ( 12 ; 12 ' ) and one with the pump laser ( 12 ; 12 ' ) pumped solid-state lasers ( 16 ; 16 ' ), which pump laser ( 12 ; 12 ' ) Pump laser radiation ( 14 ; 14 ' ) of a second wavelength, characterized in that the pump laser ( 12 ' ) a pulse pump laser ( 12 ' ) is for generating pump pulses ( 52 ) of the pump laser radiation ( 14 ) with a pump pulse interval t _{pump pulse} , which corresponds to at least one self-organization time t _{self-organization} , in which the solid-state laser ( 14 ' ) by self-organization at least one laser pulse ( 58a . 58b . 58c . 58d . 58e ) first wavelength emitted. System according to claim 9, characterized in that the pump pulse distance ( 56 ) is in a range from about 10 μs to about 500 μs and / or that a pump laser repetition rate for exciting the solid-state laser ( 16 ' ) is in a range of about 1 kHz to about 10 kHz. System according to claim 9 or 10, characterized in that an excitation _{pulse duration} t _{pulse duration of} the pump laser radiation ( 14 ' ) in a range of about 500 μs to about 10 μs and / or that the pump laser ( 12 ' ) a pulse width modulated pump laser ( 12 ' ), in particular with a duty cycle in a range of about 0.1 to about 0.5, more particularly in a range of about 0.15 to about 0.3, and / or that the pump pulse interval t _{pump pulse} at least one self-organization time t _{self-organization} corresponds in which the solid-state laser ( 16 ' ) by self-organization at least three laser pulses ( 58a . 58b . 58c . 58d . 58e ) first wavelength, in particular five laser pulses ( 58a . 58b . 58c . 58d . 58e ). System according to the preamble of claim 9, characterized in that the solid-state laser ( 16 ) a resonator ( 36 ), that the pump laser ( 12 ) is designed in the form of a continuous wave or cw laser, that the resonator ( 36 ) in a first state for the laser radiation ( 44 ) of the first wavelength is closed and in a second state for the laser radiation ( 44 ) of the first wavelength is open and that the system ( 10 ) for transferring the resonator ( 36 ) from the first to the second state and vice versa a switching device ( 38 ), with which in particular an opening time t _open for decoupling a laser pulse ( 46 ) of the first wavelength is adjustable, for which opening time the resonator ( 36 ) assumes the second state. System according to one of claims 9 to 12, characterized in that the pump laser radiation ( 14 ) has a wavelength in a wavelength range of about 1700 nm to about 2100 nm. System according to one of claims 9 to 13, characterized in that the laser pulses ( 46 ; 58a . 58b . 58c . 58d . 58e ) of the first wavelength a pulse width ( 50 ; 64 ) in a range from about 0.5 μs to about 3 μs, in particular in a range from about 1.5 μs to about 2.5 μs. System according to one of claims 9 to 14, characterized in that the pump laser ( 12 ; 12 ' ) in the form of a fiber laser ( 72 ; 72 ' ) or a modulatable diode laser, in particular in the form of a thulium fiber laser ( 74 ; 74 ' ). System according to one of claims 9 to 15, characterized in that a pumping power of the pump laser ( 12 ; 12 ' ) is in a range of about 10 W to about 500 W and / or that the first wavelength of the pulsed laser radiation ( 44 ; 44 ' ) in a wavelength range of about 1800 nm to about 2300 nm and / or that the solid-state laser ( 16 ; 16 ' ) in the form of a disk laser ( 18 ; 18 ' ) is formed with a resonator ( 36 ; 36 ' ) and one in the resonator ( 36 ; 36 ' ) arranged active laser medium ( 28 ; 28 ' ). System according to claim 16, characterized in that as an active laser medium ( 28 ; 28 ' ) a Ho-doped medium is used, in particular Ho: YAG, and / or the active laser medium ( 28 ; 28 ' ) in the form of a disk ( 30 ; 30 ' ) having a diameter in a range of about 5 mm to about 20 mm and / or a thickness in a range of about 0.1 mm to about 0.5 mm. Material processing system, in particular for processing plastics, comprising pulsed laser radiation ( 44 ; 44 ' ) emitting system ( 10 ; 10 ' ), characterized in that the pulsed laser radiation emitting system ( 10 ; 10 ' ) in the form of one of the systems ( 10 ; 10 ' ) is designed according to one of claims 9 to 17. Medical device ( 66 ), in particular in the form of a laser lithotripter ( 68 ) for the thermal treatment of kidney and ureteral stones, characterized by a system ( 10 ; 10 ' ) according to one of claims 9 to 17. Using a system ( 10 ; 10 ' ) according to one of claims 9 to 17 for material processing, in particular for plastics processing.

Images