DE102010045184A1 - Method for optronic controlling of laser oscillator amplifier configuration, involves independently controlling laser oscillator and amplifier by controlling excitation radiation or pump radiation - Google Patents

Abstract

The method involves performing longitudinal optical excitation of a laser oscillator (5) with excitation radiation of a wavelength, and longitudinally pumping an amplifier (8) with a pump radiation of another wavelength that is different from the former wavelength. The laser oscillator and the amplifier are independently controlled by controlling the excitation radiation or the pump radiation. The power of excitation radiation is controlled by the laser oscillator. The excitation radiation is conducted into the oscillator without forwarding into the amplifier. An independent claim is also included for a laser amplifier arrangement comprising a regulating device.

Description

The invention relates to a method for the optronic control of an axially arranged laser oscillator amplifier configuration comprising a laser oscillator and an amplifier for generating amplified laser radiation from radiation of the laser oscillator. The invention further relates to a laser amplifier arrangement having an axially arranged laser oscillator amplifier configuration comprising a laser oscillator and an amplifier for amplifying laser radiation generated by the laser oscillator, and to a pump source for generating at least one pump radiation having a first axial axial pumping wavelength at least of the amplifier.

For many applications, miniaturized lasers are desirable or even required which can produce pulsed laser radiation with pulse widths of a few nanoseconds and pulse energies in the range of several milli Joules, such as for long-range laser measurement systems and sensors, for material fine machining or for exciting optically non-linear processes. Diode-pumped solid-state lasers are particularly suitable for this purpose. For more details on this is on P. Peuser, NP Schmitt: "Diode pumped solid-state lasers". Springer Verlag, 1995 ., directed. The required pulse powers are typically in the range of more than 1 MW.

By means of passive Q-switching, particularly compact pulse laser oscillators can be realized, but reliable operation with high beam quality and amplitude stability is possible only at maximum pulse energies in the range of a little more than 1 mJ. In order to achieve power scaling, one or more amplifiers can be connected downstream with a multipass optical path, whereby particularly large pulse energies are achieved P. Peuser, W. Platz, P. Zeller, T. Brand, B. Kohler, M. Haag; Opt. Lett. 31 (2006) 1991 directed. However, then in general the possibilities for extensive miniaturization are considerably limited.

If the so-called longitudinal pumping geometry can be applied to the excitation of the active material, optimal conditions are created to achieve high efficiency and a high degree of compactness P. Peuser, NP Schmitt: "Diode-Pumped Solid-State Lasers", Springer Verlag, 1995 directed. It is particularly advantageous for practicable laser systems if the coupling with the power supply and control electronics can be produced over a long optical fiber connection.

The recently developed pulsed fiber lasers or fiber amplifier arrangements are characterized by a very compact design and a high beam quality; however, the available pulse powers are generally well below 1 MW, typically allowing pulse energies as high as about 1 mJ, which is insufficient for many applications.

Here, the pulse power or the pulse energy are limited by various basic physical processes. These processes are primarily ASE (Amplified Spontaneous Emission), Stimulated Brillouin Scattering, Stimulated Raman Scattering and Self-Focusing. For more details on this particular will FD Teodoro et al. Opt. Lett. 27 (2002) 518 and RL Farrow et al., Opt. Lett. 31 (2006) 3423 directed. Due to the small fiber cross section, extremely high intensities are achieved in ns pulse mode, so that the power is eventually destroyed when power is scaled. To produce a few mJ, the fiber cross-section would have to be increased so much that the beam quality would be significantly reduced.

Furthermore, in the US 6512630 B1 described a miniaturized laser configuration in which a so-called passively Q-switched microchip laser is coupled to an amplifier. The entire pump radiation is thereby provided by a single diode laser beam source and coupled in a longitudinal direction to the laser axis in the direction of the microchip laser oscillator, where it is partially absorbed in the laser crystal. After passing through the laser oscillator, the remaining pump radiation not absorbed in the oscillator, together with the laser beam generated by the microlaser, is focused by means of a lens into the amplifier crystal, although an arrangement which requires no lens is mentioned. The laser beam emerging from the oscillator is then amplified in the amplifier crystal.

However, such a configuration is not suitable for efficiently scaling the power or pulse energy, as will be explained below. There are basically two different types of pumping: quasi-continuous (quasi-cw) or pulsed excitation and continuous excitation. In quasi-continuous excitation, a single ns pulse may be generated that contains the maximum possible energy, or multiple smaller-energy pulses may be generated during a pumping cycle. In the case of pulsed excitation: When the pump power is increased, the laser pulse is generated earlier by the oscillator relative to the beginning of a pump radiation pulse of constant length. As a result, the energy stored in the amplifier can thereafter no longer be used, and the total gain can no longer be increased. This is directly related to the reduction of the overall efficiency.

With such a design, the temporal adaptation of the oscillator pulse to the pump radiation duration is crucial in order to achieve the maximum pulse energy and a high degree of efficiency.

On the other hand, with an increase in pump power and a constant duration of the diode pulse, generally several individual pulses are generated during a pump cycle, each containing a smaller pulse energy. The time interval of the pulses becomes smaller, the larger the pumping power becomes. That is, in this case, if a larger gain is to be achieved, an increase in the total pumping power simultaneously results in a change in the pulse rate.

The same applies to the case of continuous excitation. In this case, the pulse rate is increased, combined with a simultaneous reduction of the single pulse energy of the pulses generated by the laser oscillator when the total pumping power of the laser oscillator-amplifier arrangement is increased. In other words, changing the pump power or gain also causes a change in the pulse rate. In addition, the pulse width also changes since the inversion density in the laser oscillator crystal also changes. For more details on this is on AE Siegman: "Lasers", University Science Books, Mill Valley, CA, 1986, ISBN 0935702-11-5; Cape. 26, p. 1004 ff directed.

Other miniaturized laser amplifier arrangements are in the DE 10 2008 025 823 B4 and the DE 10 2008 029 776 B4 described.

The just mentioned limitations of the mentioned lasers, especially those in the US 6512630 B1 described arrangement, by the in the patent DE 10 2008 025 824 B4 essentially bypassed arrangement described. In this case, the largest part of the available pump radiation is guided around the laser oscillator by means of a lens arrangement and coupled with another optical lens in the amplifier. The control of the laser oscillator independently of the amplifier is achieved by means of a separate, fine mechanically movable lens, which is arranged in front of the centrally arranged oscillator crystal. Disadvantages of this solution are, however, that on the one hand a configuration of a plurality of optical lenses is required, which causes a lateral and longitudinal extent of the laser oscillator amplifier and thus limits the degree of miniaturization. On the other hand, the control of the oscillator and thus the temporal adaptation of the emitted pulse to the amplifier can be achieved only by a fine mechanical change in the distance of a lens mounted in front of the oscillator.

These disadvantages are completely avoided by the present invention or its advantageous embodiments, wherein preferably an ultimatum miniaturized, fully optronically controllable ns laser with high pulse power, high pulse energy and a high efficiency is made possible.

The object of the invention is to provide a method and an arrangement with which a miniaturized laser with high power and high energy and a high efficiency can be achieved.

This object is achieved by a method according to claim 1 and a laser amplifier arrangement according to claim 8.

Advantageous embodiments of the invention are the subject of the dependent claims.

In a preferred embodiment, laser radiation from at least two diode laser beam sources is used to excite a miniaturized, axially disposed solid state laser oscillator amplifier configuration in the longitudinal direction, the laser oscillator and the amplifier being controlled independently of each other, thereby providing optimum temporal and spatial alignment of the oscillator beam pulse to the amplifier is enabled.

Thus, a solution for the realization of an ultimatly miniaturized short pulse laser high pulse power and energy and a high efficiency is provided.

The method can generally be used for the optronic control of axially pumped solid-state laser-oscillator-amplifier arrangements.

• a) handheld oder Roboter-getragene Sensoren
• b) äußerst kompakte, flugzeuggetragene Lidar-Systeme
• c) Satelliten-getragene Laser-Meßsysteme
• d) Basislaser für LIMS (laser-ion mobility spectrometer)
• e) kompakte Ladarsysteme großer Reichweite

Advantageous possible uses of the invention and their advantageous embodiments are, for example:

• a) handheld or robot-borne sensors
• b) extremely compact, airborne lidar systems
• c) Satellite-borne laser measurement systems
• d) Basic laser for LIMS (laser-ion mobility spectrometer)
• e) compact long range charging systems

In one aspect, the invention provides a method for optronic control of a axially arranged laser oscillator amplifier configuration comprising a laser oscillator and an amplifier for generating amplified laser radiation from radiation of the laser oscillator, comprising the steps of:
longitudinal optical excitation of the laser oscillator with an excitation radiation of a first wavelength,
longitudinally pumping the amplifier with pump radiation of a second wavelength different from the first wavelength, and
independently controlling the laser oscillator and the amplifier by controlling at least one of the two radiation excitation radiation and pump radiation.

By the method, a laser oscillator and an associated amplifier in a laser oscillator-amplifier arrangement, which can be optimally miniaturized, independently optronisch control.

For example, it is possible to achieve maximum possible amplification and / or to optimize the efficiency.

An advantageous embodiment of the method has at least one, several or all of the following steps: controlling the power of the excitation radiation; Passing the pump radiation through the laser oscillator into the amplifier and / or passing the excitation radiation into the laser oscillator while blocking forwarding to the amplifier.

The pump radiation can be advantageously used for pumping the laser oscillator and the amplifier. For this purpose, the pump radiation is preferably passed through the laser oscillator and then into the amplifier. The excitation radiation is preferably used to control the time of emission of a laser pulse of the laser oscillator. For this purpose, it can preferably be controlled in performance. In particular, the excitation radiation is retained within the laser oscillator and not forwarded to the amplifier. By controlling the excitation radiation, one can thus control the laser oscillator independently of the amplifier. In particular, in the case of a passively Q-switched laser oscillator, by controlling the power of the excitation radiation, it is possible to control the time of a laser pulse emission and thus optimally adapt to the amplification.

Preferably, a wavelength-dependent filter device between the laser oscillator and the amplifier is used to pass the pump radiation without the excitation radiation. This may be a coating which, depending on the wavelength permeable, partially reflective or fully reflective, or z. B. be a dichroic mirror.

Preferably, at least two diode lasers are used for longitudinal excitation of the laser oscillator and the amplifier. An advantageous embodiment of the method thus comprises at least one of the following steps: generating the excitation radiation by at least one first diode laser, generating the pump radiation by at least one second diode laser, and / or controlling the excitation radiation by controlling the diode laser current of the first diode laser.

For better understanding and for better distinction, the term "excitation radiation" is used here for the radiation which essentially serves solely to excite the laser oscillator and is used for the radiation which is mainly for exciting the laser amplifier and possibly also, preferably for a smaller part , used to excite the laser oscillator, the term "pump radiation" used.

Preferably, the power of the pump radiation is set much larger than the power of the excitation radiation.

In a further advantageous embodiment of the method, the pumping radiation is used to a lesser extent for pumping the laser oscillator and for the greater part for pumping the amplifier.

A further advantageous embodiment of the method provides that the power of the pump radiation is set fixed and the power of the excitation radiation is selected variable for controlling.

A further advantageous embodiment of the method provides that the power of the pump radiation is set so large that a maximum gain is achieved in the amplifier without thermal effects or parasitic oscillations of the amplifier affecting the function of the laser oscillator amplifier configuration.

In another aspect, the invention provides a laser amplifier assembly having an axially disposed laser oscillator-amplifier configuration comprising a laser oscillator and an amplifier for amplifying laser radiation generated by the laser oscillator, a pump source for generating at least one pump radiation having a first axial axial pumping wavelength at least of the amplifier, and an excitation source for generating excitation radiation for exciting the laser oscillator at a second wavelength different from the first wavelength, wherein the Laser amplifier arrangement is arranged and designed such that the pumping radiation and excitation radiation are conducted axially into the laser oscillator, and wherein a wavelength-dependent filter device between the laser oscillator and amplifier is arranged, which is permeable to the pump radiation to pass from the laser oscillator in the amplifier for the However, excitation radiation blocking and / or reflective acts.

Such a laser amplifier arrangement is advantageously used for carrying out the method explained above.

In an advantageous embodiment of the laser amplifier arrangement, it is provided that the excitation source can be controlled and / or regulated independently of the pump source.

A further advantageous embodiment of the laser amplifier arrangement comprises a control and / or regulating device for controlling and / or regulating the power of the excitation radiation.

In a further advantageous embodiment of the laser amplifier arrangement, it is provided that the excitation source has a first diode laser and the pump source has a second diode laser.

In a further advantageous embodiment of the laser amplifier arrangement is provided that the beam power of the first diode laser is variably adjustable and the power of the second diode laser is set to a much greater power than the power of the first diode laser.

In a further advantageous embodiment of the laser amplifier arrangement is provided that the filter device
an optical coating at an interface between the laser oscillator and the amplifier, which is partially reflective for the laser radiation of the laser oscillator, antireflecting the pump radiation and highly reflective for the excitation radiation, or
a dichroic mirror which is reflective of the excitation radiation and permeable to the pump radiation.

Preferably, the laser amplifier arrangement is designed as a short pulse laser with passive Q-switching. By controlling the excitation power, the time of the laser pulse can then be controlled in order to achieve an optimum adaptation to the amplification.

Embodiments of the invention will be explained in more detail with reference to the accompanying drawings. It shows:

1 a first embodiment of a laser amplifier arrangement comprising a laser oscillator, an amplifier and at least two diode lasers for providing an excitation radiation and a pump radiation;

2 a second embodiment of the laser amplifier arrangement;

3 a third embodiment of the laser amplifier arrangement;

4 a schematic representation of the laser levels compared to wavelengths used for excitation;

5 a schematic representation of an optimal time course of a pulse of excitation radiation for the laser oscillator and a laser pulse of the laser oscillator;

6 a schematic representation of the portions of the absorbed radiation of the two diode laser for the laser oscillator and the amplifier; and

7 A fourth embodiment of the laser amplifier arrangement.

The following are based on the representation of 1 . 2 . 3 and 7 four embodiments of a laser amplifier arrangement 30 explained in more detail. In this case, the same reference numerals are used for comparable elements.

The laser amplifier arrangement 30 has a first diode laser 1 , a second diode laser 2 and a laser oscillator amplifier configuration 31 on. The laser oscillator amplifier configuration 31 has a miniature lens 4 , a laser oscillator 5 or 22 , a wavelength-dependent optical filter device 7 and an amplifier 8th on.

The first diode laser 1 serves as a source of inspiration 32 for generating an excitation radiation for the laser oscillator 5 . 22 , The second diode laser 2 serves as a pump source 34 for the laser oscillator 5 . 22 and the amplifier 8th , In the in the 1 to 3 In embodiments shown, the excitation radiation and the pump radiation are by means of an optical fiber 3 directed to the laser oscillator amplifier configuration. 7 shows an embodiment without optical fiber 3 ,

In all embodiments, the pump radiation is in a longitudinal direction on the beam axis of the by the laser oscillator amplifier Configuration generated amplified laser beam 9 initiated. Accordingly, the laser amplifier arrangement is designed for longitudinal pumping. The excitation radiation becomes coaxial with the pump radiation into the laser oscillator amplifier configuration 31 initiated. The miniature lens 4 serves for coupling the entire diode radiation formed by excitation radiation and pump radiation into the laser oscillator 5 . 22 ,

The laser oscillator 5 . 22 has an oscillator crystal 36 from laser-active medium. The amplifier 8th has an amplifier crystal 38 from laser-active medium. Laser radiation from the laser oscillator 5 is through the amplifier 8th amplified, so that the amplified laser beam 9 is produced.

In the embodiments of the 1 and 2 indicates the laser oscillator amplifier configuration 31 a passive Q-switch 6 on. This is the laser amplifier arrangement 30 as a short-time pulse laser 40 educated. The the Q-switch 6 having pulsed laser oscillator is denoted by the reference numeral 5 designated. Laser oscillators without Q-switch 6 are denoted by the reference numeral 22 designated.

In the present laser amplifier arrangement 30 becomes the radiation of at least two powerful diode lasers 1 . 2 used a solid state laser oscillator laser oscillator 5 . 22 - And an axially arranged laser amplifier amplifier 8th - visually stimulate. A special feature is that the diode lasers 1 . 2 Emit radiation in two distinct, different wavelength ranges. In this case, a so-called longitudinal pump configuration is preferably used, which offers particular advantages in terms of miniaturization, efficiency and beam quality. Preferably, the pump radiation is by means of at least one optical fiber 3 provided, which leads both diode laser radiation.

Suitable laser-active materials are, for example, the known neodymium-doped crystals such as Nd: YAG, Nd: YLF, Nd: YVO ₄ Nd: YAlO ₃ , and Nd: GGG and also corresponding, so-called ceramic laser materials. In addition, all other materials are suitable which have at least two absorption lines of different wavelengths, such as. As the ytterbium-doped crystals or materials.

The idea realized here essentially concerns short-pulse lasers 40 with passive Q-switching - passive Q-switch 6 - Wherein, however, all other laser amplifier configurations can be included, which generate, for example, quasi-continuous or single-frequency laser radiation.

In the in 1 illustrated first embodiment of the laser amplifier arrangement 30 the diode laser radiation emerging from the fiber end is used to produce a miniaturized, passively Q-switched laser oscillator 5 to pump so that a laser beam is generated whose energy in the subsequent, axially arranged amplifier 8th is increased. This is done by the laser oscillator 5 unabsorbed, greater part of the diode laser radiation excited after this the laser oscillator 5 happened.

Passive Q-switching, for example, by one in the laser oscillator 5 arranged Cr: YAG crystal can be achieved in a simple manner P. Peuser, NP Schmitt: "Diode-Pumped Solid-State Lasers", Springer Verlag, 1995 directed.

As already mentioned, the pump radiation contains two wavelength components, which are generated by at least two diode lasers. These wavelengths are chosen so that the excitation of the neodymium ions in two different laser levels can be done directly and indirectly, that is, here wavelengths in the range of about 880 nm and about 807 nm are used, as described in more detail in 4 is shown. This procedure is closer in the DE 10 2005 034 728 B4 which is expressly referred to for further details. 4 shows schematically at 12 the indirect pumping process by means of the radiation of one wavelength and at 13 the direct pumping process by means of the radiation of the other wavelength. With 14 is the laser transition designates while 15 the pumping level for indirect pumping and 16 the pump level for direct pumping called.

Both diode lasers 1 . 2 are operated simultaneously here to simultaneously generate a diode laser pulse with components of radiation of the two wavelengths.

In the present laser amplifier arrangement 30 as well as the method for controlling the same, the radiation at one of the two wavelengths is now exclusively for the optical excitation of the laser oscillator 5 whereas the radiation at the other wavelength is used to pump the laser oscillator 5 and the amplifier 8th is used.

For this purpose is filter device 7 intended. In the first embodiment, for forming the filter device 7 at the coupling-out side of the laser oscillator 5 an optical filter or an optical coating 7a attached, which reflects the first diode laser radiation and at the same time a high transmittance for the diode laser radiation at the second wavelength, thus for pumping the amplifier 8th is used.

This makes it possible by the optronic control of the power of the radiation of the first diode laser 1 determine the time of emission of the laser oscillator pulse. This will be explained below with reference to 5 explained. Therein are the time course of a pulse of the excitation radiation and a laser pulse of the laser oscillator 5 indicated over the time axis t.

As you know, the passive Q-switch switches 6 the laser activity as soon as a certain level of excitation is reached, so that the excitation energy in a laser pulse 11 discharges. Thus, by controlling the excitation power, one can control the timing of the emission of the laser pulse. The time course of the diode laser pulse used to excite 10 and the laser pulse 11 are in the scheme of 5 played.

This means, for example, that with an increase in the diode laser power of the laser pulse 11 earlier before the end of the diode laser pulse 10 is emitted. To the maximum possible gain in the amplifier crystal 38 to use, the laser pulse must 11 just before the end of the diode pulse 10 lie, which can thus be achieved in a simple manner. It is simply controlled according to the power of the excitation radiation, so that the emission of the laser pulse 10 appropriately done. This excitation radiation is passed through the filter device in the oscillator crystal 36 held and does not reach the amplifier crystal 38 , Thus, it can alone control the laser oscillator 5 be used.

Suitably, the power of the second diode laser radiation is that of the amplifier 8th pumps much higher than the power of the first diode laser radiation, which is used exclusively to excite the laser oscillator 5 serves. The second diode laser radiation passes through the laser oscillator 5 where a small part in the oscillator crystal 36 is absorbed, and then stands for optical pumping of the amplifier 8th to disposal. The power of the first diode laser radiation is variable, which is achieved by simple control of the diode laser current. This will be in 6 clarified, with the proportion 23 the laser diode laser radiation absorbed in the laser oscillator and the proportion 25 the diode laser radiation of the two diode lasers absorbed in the amplifier 1 . 2 for the laser oscillator 5 as well as for the amplifier 8th are shown. It is still the variable component 24 the absorbed diode laser radiation. As shown, the variable component 24 alone in the laser oscillator 5 absorbed.

The power of the second diode laser radiation, which to a lesser extent also for pumping the laser oscillator 5 is preferably fixed and chosen so large that in the amplifier 8th the maximum gain is achieved without any thermal effects or even parasitic oscillations of the amplifier 8th the function of the laser oscillator amplifier configuration 31 affect. In addition, in this way, the number of laser pulses generated during a pumping cycle can be adjusted.

The filter device 7 preferably has a dichroic mirror 22 on. A particularly compact or miniaturized version of the laser oscillator amplifier configuration 31 arises when the dichroic mirror 22 for the two diode laser beams as optical coating 7a directly on the outcoupling side of the laser oscillator 5 is appropriate. In this case, the amplifier crystal 38 according to the 1 directly with the laser oscillator 5 get connected.

• 1.) Einkoppelseite des Laseroszillators 5: antireflektierende (AR) Beschichtung für die beiden Diodenlaserwellenlängen bei ca. 880 nm und ca. 807 nm sowie hochreflektierende (HR) Beschichtung für die Laserwellenlänge ca. 1064 nm.
• 2.) Auskoppelseite des Laseroszillators 5: Partiell reflektierender (PR) Spiegel für die Laserwellenlänge und antireflektierend (AR) für die zweite Diodenlaserwellenlänge (880 nm oder 807 nm) sowie hochreflektierend (HR) für die erste Diodenlaserwellenlänge (entsprechend: 807 nm oder 880 nm).
• 3.) Einkoppelseite (Pumpseite) des Verstärkers 8: antireflektierend (AR) für die zweite Diodenlaserwellenlänge und antireflektierend (AR) für die Laserwellenlänge.
• 4.) Auskoppelseite des Verstärkers 8: antireflektierend (AR) für die Laserwellenlänge.

For this arrangement, the following optical coatings are provided, for example, when Nd: YAG is used as the laser material:

• 1.) Einkoppelseite of the laser oscillator 5 : antireflective (AR) coating for the two diode laser wavelengths at about 880 nm and about 807 nm and highly reflective (HR) coating for the laser wavelength about 1064 nm.
• 2.) decoupling side of the laser oscillator 5 Partially reflecting (PR) mirror for the laser wavelength and antireflective (AR) for the second diode laser wavelength (880 nm or 807 nm) and high reflectivity (HR) for the first diode laser wavelength (corresponding to: 807 nm or 880 nm).
• 3.) Einkoppelseite (pump side) of the amplifier 8th : antireflective (AR) for the second diode laser wavelength and antireflective (AR) for the laser wavelength.
• 4.) decoupling side of the amplifier 8th : antireflective (AR) for the laser wavelength.

Alternatively, the optical coating 7a for the separation of the two diode laser wavelengths also directly on the pump side of the amplifier 8th to be appropriate.

An embodiment in which the filter device 7 a discrete dichroic mirror 7b is in the 2 shown. This is an optional optical lens - miniature lens 19 - Shown with the diode laser radiation in the amplifier crystal 38 is coupled. The miniature lens 19 can be a centric bore 20 have, so that of the laser oscillator 5 emitted to be amplified laser beam unaffected by the focusing lens 19 into the amplifier crystal 38 arrives. In this picture are the oscillator crystal 36 and the amplifier crystal 38 in brackets 17 . 18 from a thermally good conductive material such. B. copper edged, which is a good derivative of the heat loss from the crystals 36 . 38 guaranteed.

The above-described method can be used except in short-pulse laser oscillator-amplifier arrangements as described in U.S. Pat 1 and 2 in principle also for optronic control of in 3 indicated laser oscillator amplifier arrangements 30 be used for the production of continuous or quasi-continuous laser radiation or even single-frequency laser radiation when the Q-switch - passive Q-switch 6 - Not used and / or the laser oscillator 22 is designed as a single-frequency laser. In this case, the essential properties of the laser beam to the performance of the entire system by the laser oscillator 22 certainly. Again, it is of considerable advantage if the power of the laser oscillator 22 regardless of the gain can be regulated. Optimal beam properties such as beam quality and pulse stability can generally only be achieved in a range of lower output powers of a laser oscillator 22 for power scaling, laser oscillator-amplifier configurations 31 be used to that of the laser oscillator 22 certain beam characteristics generated under the best possible conditions.

In 7 is still the implementation of a laser system without the use of an optical fiber 3 shown. For superposition of the diode laser radiation is in this case a dichroic mirror 21a or a polarization coupler 21b used. This arrangement can be used with pulsed laser oscillators 5 (with Q-switch 6 ) and quasi-cw or single-frequency laser oscillators 22 be used.

• a) die maximal mögliche Verstärkung und erzielt wird,
• b) der Wirkungsgrad optimiert wird,
• c) der im Laseroszillator 5, 22 erzeugte Strahl direkt und unbeeinflusst von optischen Komponenten verstärkt werden kann und
• d) sich die Zahl der pro Pumpzyklus emittierten Laserpulse 11 unabhängig von der Verstärkerleistung einstellen lässt.

Advantages of the arrangements and methods described here over known arrangements or methods are in particular:
By the measures described is achieved that a laser oscillator 5 . 22 and an associated amplifier 8th in a laser oscillator amplifier configuration 31 can be independently controlled optronically, so that

• a) the maximum possible gain and is achieved
• b) the efficiency is optimized,
• c) that in the laser oscillator 5 . 22 generated beam can be amplified directly and unaffected by optical components and
• d) the number of laser pulses emitted per pumping cycle 11 regardless of the amplifier power.

This allows high-performance laser amplifier arrangements 30 , in particular for generating ns pulses, can be realized with an extraordinarily high degree of miniaturization, high beam quality and high efficiency.

LIST OF REFERENCE NUMBERS

1

first diode laser

2

second diode laser

3

optical fiber

4

miniature lens

5

Laser oscillator (pulsed)

6

passive quality switch

7

filtering device

7a

optical coating

7b

dichroic mirror

8th

amplifier

9

amplified laser beam

10

time course of the diode laser pulse

11

laser pulse

12

indirect pumping process

13

direct pumping process

14

Laser transition

15

Pump level for indirect pumping

16

Pump level for direct pumping

17

thermally conductive crystal holder of the oscillator

18

thermally conductive Kirstallhalterung of the amplifier

19

miniature lens

20

centric puncture

21a

dichroic mirror

21b

A polarization

22

Laser oscillator (quasi-cw or single-frequency)

23

diode laser radiation absorbed in the oscillator

24

variable proportion of the absorbed diode laser radiation

25

Diode radiation absorbed in the amplifier

30

Laser amplifier arrangement

31

Laser oscillator-amplifier configuration

32

excitation source

34

pump source

36

crystal oscillator

38

crystal amplifier

40

Short pulse laser

t

timeline

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The 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

• US 6512630 B1 [0007, 0013]
• DE 102008025823 B4 [0012]
• DE 102008029776 B4 [0012]
• DE 102008025824 B4 [0013]
• DE 102005034728 B4 [0061]

Cited non-patent literature

• P. Peuser, NP Schmitt: "Diode pumped solid-state lasers". Springer Verlag, 1995 [0002]
• P. Peuser, W. Platz, P. Zeller, T. Brand, B. Kohler, M. Haag; Opt. Lett. 31 (2006) 1991 [0003]
• P. Peuser, NP Schmitt: "Diode-Pumped Solid-State Lasers", Springer Verlag, 1995 [0004]
• FD Teodoro et al. Opt. Lett. 27 (2002) 518 [0006]
• RL Farrow et al., Opt. Lett. 31 (2006) 3423 [0006]
• AE Siegman: "Lasers", University Science Books, Mill Valley, CA, 1986, ISBN 0935702-11-5; Cape. 26, p. 1004 ff. [0011]
• P. Peuser, NP Schmitt: "Diode-Pumped Solid-State Lasers", Springer Verlag, 1995 [0060]

Claims (15)

Method for the optronic control of an axially arranged laser oscillator amplifier configuration ( 31 ), which is a laser oscillator ( 5 . 22 ) and an amplifier ( 8th ) for generating amplified laser radiation ( 9 ) of radiation of the laser oscillator ( 5 . 22 ), comprising the steps of: longitudinal optical excitation of the laser oscillator ( 5 . 22 ) with an excitation radiation of a first wavelength, longitudinal pumping of the amplifier ( 8th ) with a pump radiation of a second wavelength different from the first wavelength, and independent control of the laser oscillator ( 5 . 22 ) and the amplifier ( 8th ) by controlling at least one of the two radiations excitation radiation and pump radiation. Method according to Claim 1, characterized by at least one of the following steps: controlling the power of the excitation radiation, passing the pump radiation through the laser oscillator ( 5 . 22 ) in the amplifier ( 8th ) and / or conducting the excitation radiation into the laser oscillator ( 5 . 22 ) while blocking a forwarding in the amplifier ( 8th ). Method according to one of the preceding claims, characterized by generating the excitation radiation by at least one first diode laser ( 1 ), Generating the pump radiation by at least one second diode laser ( 2 ), and controlling the excitation radiation by controlling the diode laser current of the first diode laser ( 1 ). Method according to one of the preceding claims, characterized in that the power of the pump radiation is set much larger than the power of the excitation radiation and / or that the pump radiation is partly used to pump the laser oscillator ( 5 . 22 ) and partly for pumping the amplifier ( 8th ) is used and / or that the power of the pump radiation is set fixed and the power of the excitation radiation is chosen to be variable for controlling and / or that the power of the pump radiation is set so large that in the amplifier ( 8th ) a maximum gain is achieved without thermal effects or parasitic oscillations of the amplifier ( 8th ) the function of the laser oscillator amplifier configuration ( 31 ). Method according to one of the preceding claims, characterized in that the excitation radiation and the pump radiation are generated as variable portions of two wavelength components of a common radiation pulse. Method according to one of the preceding claims, characterized in that the laser oscillator ( 5 ) is a passively Q-switched laser oscillator and that by controlling the power of the excitation radiation, the time of emission of a laser pulse to be amplified ( 11 ) is controlled. Method according to one of the preceding claims, characterized in that the excitation radiation and / or the pump radiation are fiber-coupled to the laser oscillator amplifier configuration ( 31 ). Laser amplifier arrangement ( 30 ) with an axially arranged laser oscillator amplifier configuration ( 31 ), which is a laser oscillator ( 5 . 22 ) and an amplifier ( 8th ) for amplifying by the laser oscillator ( 5 . 22 ) generated laser radiation, a pump source ( 34 ) for generating at least one pump radiation having a first wavelength for axial longitudinal pumping of at least the amplifier ( 8th ), and an excitation source ( 32 ) for generating excitation radiation for exciting the laser oscillator ( 5 . 22 ) having a second wavelength different from the first wavelength, the laser amplifier arrangement ( 30 ) is arranged and configured such that the pump radiation and excitation radiation are transmitted axially into the laser oscillator ( 5 . 22 ), and wherein a wavelength-dependent filter device ( 7 ) between laser oscillator ( 5 . 22 ) and amplifiers ( 8th ), which is transparent to the pumping radiation and impermeable to the excitation radiation and / or reflective. Laser amplifier arrangement ( 30 ) according to claim 8, characterized in that the power of the excitation source ( 32 ) regardless of the power of the pump source ( 34 ) is controllable and / or controllable. Laser amplifier arrangement ( 30 ) according to claim 8 or 9, characterized by a control and / or regulating device for controlling and / or regulating the power of the excitation radiation. Laser amplifier arrangement ( 30 ) according to one of claims 8 to 10, characterized in that the excitation source ( 32 ) a first diode laser ( 1 ) and the pump source ( 34 ) a second diode laser ( 2 ) having. Laser amplifier arrangement ( 30 ) according to claim 11, characterized in that the beam power of the first diode laser ( 1 ) variably adjustable and the power of the second diode laser ( 2 ) to a much greater power than the power of the first diode laser ( 1 ) is set. Laser amplifier arrangement ( 30 ) according to one of claims 11 or 12, characterized in that the first (1) and the second diode laser ( 2 ) for the simultaneous emission of a diode radiation pulse, which is formed from the radiation of the first and the second diode laser, are to be controlled. Laser amplifier arrangement ( 30 ) according to one of the preceding claims, characterized in that the filter device ( 7 ) an optical coating ( 7a ) at at least one interface between the laser oscillator ( 5 . 22 ) and the amplifier ( 8th ), which is permeable to the pump radiation and reflective to the excitation radiation, or a dichroic mirror ( 7b ), which is reflective to the excitation radiation and transmissive to the pump radiation. Laser amplifier arrangement ( 30 ) according to one of the preceding claims, characterized in that between the first and / or the second diode laser ( 1 . 2 ) on the one hand, and the laser oscillator amplifier configuration ( 31 ) On the other hand, at least one fiber ( 3 ) for directing the excitation radiation and / or the pump radiation into the laser oscillator amplifier configuration ( 31 ) is provided.

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