Laser apparatus and respective optoelectronic devices for emitting ultrashort light pulses with high energy and high repetition rate

Abstract

The present invention relates to a laser device for emitting ultrashort light pulses with high energy and high repetition rate, and to an optoelectronic device using said laser device. In particular, said optoelectronic device is particularly suitable for use in precision machining. Furthermore, the present invention also relates to a method for emitting packets of ultrashort light pulses with high energy and high repetition rate by means of said optoelectronic device.

Description

[Technical field]

[0001] The present invention relates to a laser apparatus for emitting ultrashort optical pulses with high energy and high repetition rate, and to optoelectronic devices using said laser apparatus.

[0002] In particular, the aforementioned optoelectronic devices are particularly suitable for use in precision laser processing.

[0003] Furthermore, the invention also relates to a method for emitting packets of ultrashort light pulses with high energy and high repetition frequency by means of said optoelectronic device. [Background technology]

[0004] Different types of devices for emitting ultrashort light pulses are known in the art, in particular laser devices.

[0005] Typically, these devices are used in industrial applications of micromachining and / or microsoldering, as they allow extremely precise delivery of light energy. In fact, it is possible to use ultrashort pulsed laser devices to manufacture two-dimensional (2D) and three-dimensional (3D) structures of almost any shape with submicron dimensions by direct stereolithography techniques. An example of this application is femtosecond lithography, where ultrashort pulsed laser devices are used for direct engraving or imprinting of photosensitive masks on materials.

[0006] Of course, these devices are also commonly used in other applications such as nonlinear optics, biophotonics, and life sciences.

[0007] In general, such a device consists of an oscillator, a stretcher, a multi-stage amplifier, and a compressor.

[0008] The oscillator delivers a number of low energy pulses, for example a train of consecutive pulses, typically of a few picojoules, with durations of the order of a few hundred femtoseconds down to a few picoseconds. The pulses are sampled by a modulator, the purpose of which is to reduce the repetition rate of the initial pulses. Selected pulses are stretched in time by a stretcher up to a few hundred picoseconds, injected into a chain of optical amplifiers to reach the energy required for the particular application considered, and then compressed by a compressor at their initial duration.

[0009] This technique makes it possible to obtain single equally spaced pulses with temporal separation that can vary from milliseconds to just below microseconds, where the energy of each pulse ranges from a few hundred nanojoules to a few millijoules.

[0010] By subsequently focusing these pulses on the surface of the material to be treated, it is possible to carry out micromachining in a very precise manner. However, the use of these laser devices entails a compromise at the application level in the processing of the material: as the processing speed increases, the precision decreases. This compromise arises because, with this approach of pulses spaced equally in time, it is necessary to increase the energy of each individual pulse in order to increase the processing speed.

[0011] As a result, to obtain a processing speed compatible with a particular industrial application, the energy of each output pulse from the amplifier is maintained well above the appropriate processing threshold, This excess energy results in the formation of a dense plasma cloud around the processing point, limiting processing efficiency and accuracy.

[0012] A solution to this drawback is provided by laser devices with ultrashort pulse packets and high repetition rates, which allow high processing efficiency since each output pulse has enough energy to remove the material but not enough to generate spurious phenomena, and also high removal accuracy since the absence of a plasma cloud determines the excellent ballistic accuracy of the photons of the light pulse incident on the material.

[0013] Such devices use oscillators that emit packets containing ultrashort light pulses with high repetition rates but low energies, typically a few picojoules, and therefore the energy of each pulse in each packet must subsequently be amplified, typically through a multi-stage amplification chain, to raise it to a value compatible with the needs of the device's application.

[0014] As can be appreciated, the fact that the oscillator can only emit low energy light pulses in order to operate safely and stably causes a significant increase in the structural complexity of the device, as well as high manufacturing costs for the device, since multiple amplifiers are required to safely increase the pulse energy without damaging the device.

[0015] Furthermore, these laser devices result in the use of stretchers and compressors to amplify the femtosecond-scale optical pulses, thus further increasing the complexity and cost of the device itself.

[0016] Therefore, it is necessary to design and manufacture a laser apparatus for emitting ultrashort optical pulses with high repetition rate and high energy, and an optoelectronic device using the laser apparatus, which makes it possible to overcome the above-mentioned shortcomings of the prior art. Summary of the Invention [Problem to be solved by the invention]

[0017] The main object of the present invention is to provide a laser apparatus for emitting ultrashort light pulses with high repetition rate and high energy, and an optoelectronic device using said laser apparatus, which makes it possible to overcome the above-mentioned drawbacks of the prior art.

[0018] Another object of the present invention is to provide a laser device for emitting ultrashort light pulses with high energy and high repetition frequency, which can be used safely and with high operational stability, preventing damage to the internal components of such a laser device after several cycles of use.

[0019] Another object of the present invention is to provide an optoelectronic device for the emission of multiple packets of ultrashort optical pulses with high energy and high repetition frequency, which allows a lower manufacturing and construction complexity than the devices taught by the prior art, with the same efficiency.

[0020] It is a further object of the present invention to provide an optoelectronic device for the emission of multiple packets of ultrashort optical pulses with high energy and high repetition rate, which allows a cost reduction with respect to the devices taught by the prior art.

[0021] Another object of the present invention is to provide an optoelectronic device for emitting multiple packets of ultrashort optical pulses with high energy and high repetition frequency enabling optimized speed and quality of operation, as well as higher processing efficiency.

[0022] Finally, another object of the present invention is to provide an optoelectronic device for the emission of multiple packets of ultrashort optical pulses with high energy and high repetition frequency, which also allows high scalability. [Means for solving the problem]

[0023] According to an aspect of the present invention, there is provided a laser device for emitting multiple ultrashort light pulses with high energy and high repetition rate according to claim 1.

[0024] According to another aspect of the present invention there is provided an optoelectronic device for emitting multiple packets of ultrashort optical pulses with high energy and high repetition frequency according to claim 16.

[0025] According to a further aspect of the invention there is provided a method for emitting multiple packets of ultrashort light pulses with high energy and high repetition frequency according to claim 30.

[0026] The dependent claims refer to preferred and advantageous embodiments of the invention. [Brief description of the drawings]

[0027] Other features and advantages of the invention will become more apparent from the description of an example of an embodiment of a laser device for emitting a plurality of ultrashort light pulses with high energy and high repetition frequency and an optoelectronic device for emitting packets of a plurality of ultrashort light pulses with high energy and high repetition frequency, which is shown by way of example in the accompanying drawings. [Figure 1] 1 is a block diagram of a light-emitting laser device according to an embodiment of the present invention. [Diagram 2] 1 is a block diagram of an optoelectronic device according to one embodiment of the present invention; [Diagram 3] 3 shows a more detailed block diagram of a modulation means used in an optoelectronic device according to the example embodiment of FIG. 2; [Figure 4] 3 shows a more detailed block diagram of an amplification means used in an optoelectronic device according to the example embodiment of FIG. 2; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] In the accompanying drawings, identical parts or components are designated by the same reference numerals.

[0029] With reference to the accompanying drawings, reference number 3 denotes a laser device emitting multiple 2 ultrashort light pulses 2a with high energy and high repetition rate according to an example embodiment of the present invention.

[0030] The light emitting laser device 3 is particularly, but not exclusively, suitable for use in optoelectronic devices for industrial applications, such as for example micromachining and / or microsoldering of materials.

[0031] It should be noted that the term "ultrashort light pulse" refers to each light pulse 2a having a duration on the order of about 10 picoseconds to about 10 femtoseconds.

[0032] In particular, the light emitting laser device 3 according to the present invention is preferably designed to emit a plurality of light pulses 2a each having a duration of about 5000 femtoseconds to about 100 femtoseconds, optionally about 1000 femtoseconds to about 100 femtoseconds, or about 500 femtoseconds to about 100 femtoseconds, for example about 300 femtoseconds.

[0033] It should also be noted that the term "high energy light pulse" should be considered in relation to the typical energy values ​​of light pulses emitted by light emitting devices, and more particularly by laser oscillators according to the prior art, which light pulses have been demonstrated to be of the order of a few picojoules.

[0034] The laser device 3 for emitting a plurality of ultrashort light pulses 2a with high energy and high repetition rate according to the present invention has a repetition rate f of about 500 MHz or more, or even about 750 MHz or more, e.g. 1 GHz. r wherein each light pulse 2a of the plurality 2 of ultrashort light pulses 2a has an energy value E p has.

[0035] Obviously, a repetition rate of about 500 MHz or more, f r Emitting a plurality 2 of ultrashort light pulses 2a with a time interval of about 2 ns or less from the next light pulse means that each light pulse 2a of the plurality 2 has a time interval of about 2 ns or less from the next light pulse.

[0036] According to a non-limiting example of an embodiment of the present invention, the light emitting laser device 3 has a repetition rate f equal to about 1 GHz. r , resulting in the emission of a plurality 2 of ultrashort light pulses 2a with a time interval of each light pulse 2a equal to about 1 ns from the next light pulse.

[0037] As can be appreciated, the time interval of each light pulse 2a is different to its duration, which is the time during which the light intensity of the pulse 2a remains above 50% of its peak value, which in the case of the present invention, as described above, is preferably from about 5000 femtoseconds to about 100 femtoseconds, optionally from about 1000 femtoseconds to about 100 femtoseconds, or from about 500 femtoseconds to about 100 femtoseconds, for example about 300 femtoseconds.

[0038] High repetition rate f r The use of the energy value E p However, in the present invention, the light emitting laser device 3 has a high repetition rate f r The high energy E of each of the multiple light pulses 2a p can be effectively matched.

[0039] The light emitting laser device 3 may suitably be or comprise a laser oscillator 3a, such as a vertical cavity surface emitting laser oscillator or VCSEL, or preferably, according to the non-limiting example of an embodiment of the invention shown in the figures, a solid state laser oscillator 3a, which preferably operates, in use, in a mode-locked operating mode, optionally in a passive mode-locked operating mode.

[0040] In another embodiment of the invention, the laser of the solid-state oscillator 3a, in use, can be operated in an active mode-locked mode of operation, for example using an electro-optic or acousto-optic modulator, however this active mode-locked mode generally has the drawback that it is only possible to sustain or modify the optical pulses 2a down to the order of picoseconds, whereas in a passive mode-locked mode it is possible to reach the order of femtoseconds.

[0041] The mode-locking technique allows the generation of multiple 2 ultrashort optical pulses 2a by introducing a predetermined phase relationship between the modes, i.e. wavelengths, of the resonant cavity of the oscillator 3a, as will be explained in more detail below.

[0042] More specifically, the modes of the resonant cavity periodically interfere with each other in a constructive manner, generating optical pulses 2a whose duration depends on the intrinsic properties of the oscillator 3a.

[0043] In particular, the laser oscillator 3a is preferably designed such that, in use, it is first switched or converted into a resonant light and then into a plurality 2 of ultrashort light pulses 2a, each of which is then converted to an energy E p The optical fiber 10 comprises pumping means 3b adapted to generate at least one optical source adapted to amplify a light beam emitted from the optical fiber 10 and a resonant cavity RC including directing means 3c.

[0044] In this regard, the pumping means 3b may preferably comprise at least one gain means 6 and at least one pumping element 7 configured to emit at least one pumping light beam PB1 or optical light source in use, while the directing means 3c may preferably be designed to direct the multiple 2 ultrashort light pulses 2a or resonant light towards the gain means 6 and direct the multiple 2 ultrashort light pulses 2a or resonant light amplified by the pumping means 3b from the gain means 6 towards the output of the resonant cavity RC and vice versa, i.e. back into the interior of the resonant cavity RC.

[0045] As will be seen in more detail below, the pump light beam PB1 also constitutes the optical light source of the light-emitting laser device 3 which is first resonant and then converted into a plurality of ultrashort light pulses 2a. In practice, the pumping element 7 is arranged to emit at least one pump light beam PB1 which, in use, also constitutes the optical light source of the light-emitting laser device 3 at the same time. It should be considered that the optical light source can resonate to become resonant only if the resonance conditions detailed below are fulfilled.

[0046] Preferably, the pumping means 3b also comprises at least one focusing element 15 adapted to focus at least one pumping light beam PB1 emitted by the pumping element 7 towards the gain means 6, e.g. towards at least one lens 15, in order to obtain a pumping light beam PB1 having a diameter dimensionally matched to the resonant mode supported by the resonant cavity RC in the gain means 6.

[0047] The at least one gain means 6 may be or may comprise at least one ytterbium ion doped crystal, for example of the Yb:YAG or Yb:CALGO type, having an emission wavelength of about 1020 nm to about 1080 nm.

[0048] On the other hand, the at least one pumping element 7 may preferably be or comprise at least one laser diode configured to emit at least one pumping light beam PB1 with a power of about 5 W to about 20 W and, optionally, with an emission wavelength of about 935 nm to about 985 nm.

[0049] According to the example embodiment of the invention shown in FIG. 1, the laser diode is operated in a continuous wave or CW regime, ie, during use, provides a continuous pump light beam PB1 over time.

[0050] In particular, the at least one laser diode is preferably an optical fiber coupled laser diode terminated with a collimator so as to emit a pump light beam PB1 having a flat wavefront.

[0051] According to a non-limiting example of an embodiment of the invention shown in FIG. 1, the at least one gain means 6 is a crystal doped with ytterbium ions of the Yb:YAG type, while the at least one pumping element 7 is a laser diode configured to emit at least one pumping light beam PB1 with a power of about 20 W.

[0052] Ytterbium ion doped crystals of the Yb:YAG type have been advantageously chosen as the gain means 6 in the example embodiment shown in FIG. 1 since they exhibit very low quantum defects, very high efficiency and high thermomechanical performance and therefore make it possible to obtain a plurality of ultrashort light pulses 2a at the output of the oscillator 3a with high average power, for example up to about 10 W, due to the high emission power of the pumping light beam PB1.

[0053] The resonant cavity RC, or more specifically the guiding means 3c, may preferably comprise one or more first guiding elements 8, 9, 10 adapted to guide the resonant light in the resonant cavity RC or the plurality of ultrashort optical pulses 2a towards the gain means 6, and one or more second guiding elements 11, 12, 13, 14 adapted to guide the resonant light in the resonant cavity RC or the plurality of ultrashort optical pulses 2a, amplified by the pumping means 3b, from the gain means 6 towards the output of the resonant cavity RC and vice versa, i.e. back to the inside of the resonant cavity RC.

[0054] Essentially, as will be better understood below, a first portion of the energy of each of the plurality of ultrashort optical pulses 2a, which is amplified by the pumping means 3b, is transmitted to the output by the oscillator 3a, while a second portion of the energy is reflected back into the resonant cavity RC via a reverse optical path.

[0055] With regard to the one or more first inductive elements 8, 9, 10, at least one of them guiding elements 8 may preferably be or comprise a conversion means 8a adapted to convert the optical light source generated by the pumping element 7 in a plurality 2 of ultrashort light pulses 2a and subsequently directing said plurality 2 of ultrashort light pulses 2a towards the gain means 6.

[0056] It is considered that the wavelengths of the plurality 2 of optical pulses 2 a are equal to the wavelengths of the resonant light in the resonant cavity RC, and therefore, saying that a given optical element has a given percentage reflectance and / or transmittance at the wavelengths of the plurality 2 of optical pulses 2 a is equivalent to saying that it has the same reflectance and / or transmittance at the wavelengths of the resonant light in the resonant cavity RC.

[0057] In particular, these conversion means 8a are or preferably include saturable absorbers, optionally solid-state saturable absorbers or SESAMs, or nonlinear mirrors, both of which are designed to induce a nonlinear modulation of the amplitude of the resonant electric field that facilitates the functioning of the resonant cavity RC in the pulsed state. More specifically, the nonlinear mirror comprises a nonlinear crystal intended for the generation of the second harmonic in use, and a dichroic mirror used in combination with this nonlinear crystal, which is configured with a reflectivity of about 99% or more at green wavelengths, i.e. from about 520 nm to about 565 nm, and a reflectivity of about 95% or more at the wavelengths of the multiple 2 ultrashort light pulses 2a.

[0058] Instead, the saturable absorber is an optical device that, like the nonlinear mirror described above, has a reflectivity that depends on the intensity of the incident light, i.e., behaves differently depending on the intensity of the incident light. In the non-limiting example of an embodiment of the invention in which the solid-state laser oscillator 3a operates in use in a passive mode-locked mode of operation, this saturable absorber is in fact a passive element required to force the generation of longitudinal modes with the same phase within the resonant cavity RC.

[0059] Essentially, the saturable absorber attenuates low intensity constant wavelength light, but due to the rather random fluctuations experienced by the oscillator 3a, any peaks of light intensity are generally more effectively reflected, as a result of which an impulse mode-locking state is established. When the resonant light in the resonant cavity RC exceeds a certain intensity, a selective amplification process of high intensity noise peaks is established due to the higher absorption of the low intensity light by the saturable absorber or SESAM. After many resonance turns or cycles in the resonant cavity RC, a plurality 2 of ultrashort light pulses 2a are then generated, or in any case, the optical light source emitted by the pumping element 7 is first converted into resonant light and then into a plurality 2 of ultrashort light pulses 2a, for example via a combination of the resonant cavity RC with the guiding means 3c, more particularly the conversion means 8a, and the gain means 6 of the pumping means 3b. In practice, the saturable absorber allows the transition from an ignition phase, in which the light emitting laser device 3 operates in a continuous wave state, to a stable phase, in which the light emitting laser device 3 operates in a pulsed state.

[0060] It should be noted that in certain circumstances, for example when using solid-state saturable absorbers or SESAMs, an instability, also called Q-switching instability, may occur. Such instability is usually caused by the saturable absorber "rewarding" the increase in the energy of the light pulse 2a in the resonant cavity RC, which exceeds the saturation intensity threshold, by a decrease in losses, so that in various resonance cycles in the resonant cavity RC, the energy of the light pulse 2a can be amplified in the gain means 6 more than in the continuous emission, and thus, after a number of cycles, is dominated by the gain means 6 by establishing a pulsed mode-locked state. Thus, unless the saturation of the saturable absorber is strong enough during the transition process from the continuous state to the pulsed state, the aforementioned Q-switching instability may occur, which may destabilize the oscillator 3a, or in the worst case, even burn or disable the internal components of the resonant cavity RC.

[0061] Moreover, mitigating such Q-switching instability is even more complicated when ultrashort light pulses 2a with high repetition frequency are generated in the resonant cavity RC. Indeed, the energy of each light pulse 2a is related to the repetition frequency by an inverse proportional relationship, i.e. higher frequencies correspond to lower energies, which determines that during the ignition stage of the light-emitting laser device 3, when the light-emitting laser device 3 is passing from a continuous wave state to a pulsed state, both the gain and conversion means 8a, more specifically the saturation capacity of the saturable absorber 8a, are low and therefore prone to Q-switching instability.

[0062] In this context, in order to be able to generate a light emitting laser device 3, more particularly an oscillator 3a, capable of emitting a plurality 2 of ultrashort light pulses 2a with high energy at a high repetition rate that allows it to be used safely and with high operational stability, it is advantageous, or in any case appropriate, for the size of the resonant light beam incident on the gain means 6 to remain unchanged from the ignition phase in the continuous state until the stabilization phase of the pulsed state, for example to avoid burning out of the saturable absorber or, more generally, of the optical components of the resonant cavity RC.

[0063] With regard to this aspect, it is known that thermal lensing, i.e. the effect of volume expansion causing curvature of the surface of the gain means in response to its non-uniform temperature increase, can affect the stability of the resonant cavity. In particular, thermal lensing typically produces significant variations in the size of the resonant light, which tends to promote instabilities in Q-switched mode-locking, where very large variations in the oscillating electric field can burn out the saturable absorber, or in any case the components of the resonant cavity.

[0064] For this purpose, the resonant cavity RC is preferably designed such that it is not affected by the thermal lensing effects generated by the incidence of the pump light on the gain means 6 during its pumping, in the sense that the size of the resonant light, or rather the resonant light beam, is substantially not affected by the thermal lensing effects generated by the incidence of the pump beam on the gain means 6 during its passage through the light emitting laser device 3 from a continuous wave state to a pulsed state.

[0065] Specifically, what was first studied by the ABCD matrix model and finally observed empirically is that by placing the focus of the resonant light, or better the focus of the resonant light beam, within a certain distance interval with respect to one of the at least two faces of the gain means 6 that this resonant light crosses, the size of the resonant light is substantially unaffected by the thermal lensing effect generated by the incidence of the pump beam on the gain means 6 during its passage through the light emitting laser device 3 from the continuous wave state in the pulsed state, i.e. the size of the resonant light beam remains substantially constant during this passage and therefore the aforementioned repetition frequency value f r and pulse energy E p The aim of this invention is to enable optimal operational stability even with the use of a passive mode-locked operating mode having

[0066] In this regard, the resonant cavity RC may be preferably configured such that the focal point of the resonant light is located at a distance in the range of about 5 mm to about 30 mm from one of the at least two faces of the gain means 6 with which the resonant light intersects.

[0067] This allows for a size of the resonant light, or rather the resonant light beam, incident on the gain means 6 that does not change appreciably between the ignition phase and the pulsed stable phase of the light emitting laser device 3. By doing so, it is possible to fix the size of the resonant light incident on the gain means 6 such that the gain and the saturable absorber are effectively saturated, minimizing Q-switching instabilities.

[0068] According to another embodiment of the invention, the passive mode-locking mode of operation can be implemented by Kerr-lens mode-locking or KLM techniques, or by a hybrid technique, ie a combination of KLM and SESAM.

[0069] The one or more first inductive elements 8, 9, 10 may then be or may comprise a concave mirror 9, if desired having a concave surface facing the subsequent first inductive element 10 towards the gain means 6 along the path of the multiple 2 optical pulses 2a within the resonant cavity RC, configured with a reflectivity of about 99% or more at the wavelengths of the multiple 2 ultrashort optical pulses 2a, and / or may be or may comprise a flat dichroic mirror 10, if desired, configured with a reflectivity of about 99% or more at the wavelengths of the multiple 2 ultrashort optical pulses 2a and a transmittance of about 95% or more at the wavelength of the pumping light beam PB1 emitted by the pumping element 7.

[0070] In practice, the dichroic mirror 10 allows the transmission of the pumping light beam PB1 towards the gain means 6 and at the same time allows the reflection of the resonant light or multiple 2 light pulses 2a in the resonant cavity RC towards the gain means 6, thereby pumping the gain means 6 and amplifying each light pulse 2a.

[0071] Alternatively, with regard to the one or more second inductive elements 11, 12, 13, 14, these inductive elements are or comprise at least one reflective and transmissive element or coupler 14 configured to enable transmission of a first portion of the energy of the resonant light or of the plurality of ultrashort optical pulses 2a in the resonant cavity RC, amplified by the pumping means 3b, to the output of the oscillator 3a, and feedback or reflection of a second portion of the energy of the resonant light or of the plurality of ultrashort optical pulses 2a in the resonant cavity RC, amplified by the pumping means 3b, back into the resonant cavity RC via a reverse optical path.

[0072] Of course, the percentage of the first portion of the energy of the resonant light in the resonant cavity RC or the multiple 2 ultrashort light pulses 2a that is transmitted from the oscillator 3a, and the percentage of the second portion of the resonant light energy in the cavity resonance RC or the multiple 2 ultrashort light pulses 2a that is reflected, strictly depends on the structural features of the reflecting and transmitting element or coupler 14, or its reflectivity and transmittance percentages.

[0073] Such at least one reflective and transmissive element or coupler 14 may be or may comprise a semi-reflective mirror, preferably configured with a partial reflectance of about 75% to about 95% at the wavelength of the plurality of ultrashort light pulses 2a, and consequently a transmittance of about 5% to about 25% at the wavelength of the plurality of ultrashort light pulses 2a.

[0074] Essentially, a portion of the radiation comprising about 5% to about 25% of the total radiation of each of the plurality 2 of ultrashort light pulses 2a is transmitted and therefore exits the light emitting laser device 3, or more specifically exits the oscillator 3a, while the remaining portion of the radiation comprising about 75% to about 95% of the total radiation of each of the plurality 2 of ultrashort light pulses 2a is reflected and remains within the resonant cavity RC in order to maintain the resonance of the resonant cavity RC.

[0075] It is pointed out that the transmittance and reflectance values ​​of the at least one reflective and transmitting element or coupler 14 are preferably selected such that the gain generated by the amplification of the plurality 2 of optical pulses 2a by the pumping means 3b exceeds the losses introduced by the guiding means 3c of the resonant cavity RC. In fact, the transmittance value of the at least one reflective and transmitting element or coupler 14 constitutes the losses of the resonant cavity RC. In this regard, if the transmittance value of the at least one reflective and transmitting element or coupler 14 is too high, the losses will exceed the gain and the resonant cavity RC will not resonate.

[0076] In general, the gain is defined by the power value injected into the gain means 6 by the pumping element 7, by how doped the gain means 6 is, and by the diameter of the focus of the pumping light beam PB1 emitted by the pumping element 7 in the gain means 6, while the loss can be considered to be approximately estimated as the sum of all the transmittance values ​​of the guiding means 3c constituting the resonant cavity RC.

[0077] Furthermore, the one or more second inductive elements 11, 12, 13, 14 may optionally be or comprise at least a first dichroic mirror 11 configured with a reflectivity of about 99% or more at the wavelength of the resonant light or the plurality of ultrashort light pulses 2a and with a transmittance of about 95% or more at the wavelength of the pumping light beam PB1 emitted by the pumping element 7, and / or a concave second mirror 13, optionally with a concave surface facing the subsequent second inductive element 13 along the optical path in the resonant light or the plurality of ultrashort light pulses 2a towards the output of the oscillator 3a, configured with a reflectivity of about 99% or more at the wavelength of the plurality of ultrashort light pulses 2a, and / or a third mirror 13, preferably of Gires-Tournois type, configured to support the generation of solitons in the resonant cavity RC.

[0078] This third mirror 13 of the Gears-Tournois type should in fact be considered as an element making it possible to reach and / or sustain durations of the light pulses 2a of the femtosecond order.

[0079] In this regard, having an optical pulse 2a of the femtosecond order is equivalent, in terms of frequency domain, to a spectral bandwidth of the order of a few nanometers. This leads to a large chromatic dispersion of the longitudinal resonant modes in the resonant cavity RC, which generally "scatters" the wavelength components of the optical pulse 2a and does not allow the generation and maintenance of optical pulses 2a with time durations of less than a few picoseconds. The third mirror 13 of the Gears-Tournois type, which introduces a negative group velocity dispersion in the resonant modes of the resonant cavity RC, instead makes it possible to support the generation of solitons within it in order to reach and / or maintain optical impulses 2a with durations of the femtosecond order.

[0080] In summary, the one or more first inductive elements 8, 9, 10 and the one or more second inductive elements 11, 12, 13, 14 define an optical path that enables optical resonance of the plurality 2 of ultrashort optical pulses 2 a in the resonant cavity RC and coupling or transmission of a portion of the energy of each of the plurality 2 of ultrashort optical pulses 2 a at the output from the oscillator 3.

[0081] As for the pumping process, it is carried out by the pumping means 3b. More specifically, an optical light source, such as at least one pumping light beam PB1 emitted by the pumping element 7, stimulates the transition of the atoms of the active means, such as at least one gain means 6, from the ground state to an excited state, creating a population inversion. The atoms of the active means in the excited state release energy in the form of photons having lower energy and therefore longer wavelength than the photons of the pumping beam PB1, since part of the energy introduced through the pumping process becomes phonons and then heat. At this point, after satisfying the resonance condition, in which the gain of the resonant cavity RC must be greater than the loss, the energy is re-emitted through a process of stimulated emission, in which the photons emitted in the propagation direction defined by the alignment of the guiding means 3c of the resonant cavity RC are amplified, such as resonant light during a first time interval, i.e. an ignition phase, in which the light-emitting laser device 3 operates in a continuous state, and a plurality 2 of amplified ultrashort light pulses 2a during a second time interval, i.e. a phase in which the light-emitting laser device 3 operates in a pulsed state.

[0082] A non-limiting example of the operation of the light emitting laser device 3 according to one embodiment of the present invention shown in FIG. 1 will now be described.

[0083] The optical light source, as well as the pump light source, is constituted by a pumping light beam PB1 emitted by a laser diode 7. At the initial stage of operation of the light-emitting laser device 3, more particularly the oscillator 3a, the laser diode 7 emits a pumping light beam PB1 in the continuous wave state, for example at a wavelength of about 940 nm, which is focused via a lens 15 and transmitted through a dichroic mirror 10 in the Yb:YAG crystal 6, thus stimulating a population inversion of the atoms of the Yb:YAG crystal 6 due to the accumulation of energy in the Yb:YAG crystal 6. The wavelength of the pumping light beam PB1 leaving the Yb:YAG crystal is equal to the emission wavelength typical of this active means, for example about 1030 nm. This radiation is then re-emitted in each direction by the gain means 6, but only those photons that are re-emitted along an imaginary line defined by the alignment of the guiding means 3c constituting the resonant cavity RC are amplified by the stimulated emission, and if the gain of the resonant cavity RC overcomes its losses, it can resonate and effectively generate resonant light in the resonant cavity RC. In the positive case, the resonant light thus generated continues towards the dichroic mirror 11 of one or more second guiding elements 11, 12, 13, 14. From here, this resonant light, having a wavelength equal to about 1030 nm, is directed respectively by the second concave mirror 12 and the third mirror 13 of the Gears-Tournois type towards the semi-reflective mirror 14. Here, part of the energy of the resonant light is reflected back along the optical path mentioned above, and another part of the energy is transmitted at the output of the oscillator 3a. Naturally, the proportion of transmitted and reflected energy is dictated by the structural characteristics of the semi-reflective mirror 14.

[0084] After a number of operating cycles, the energy of the resonant light becomes sufficient to saturate the saturable absorber or SESAM 8a, thus allowing the oscillator 3a to pass from a continuous wave state to a pulsed state, in effect enabling the conversion of the continuous resonant light in a plurality 2 of ultrashort optical pulses 2a.

[0085] Following the conversion, the multiple 2 ultrashort light pulses 2a are directed back towards the Yb:YAG crystal by one or more first guiding elements 8, 9, 10 via a saturable absorber or SESAM 8a, so that the actual amplification takes place. In this regard, the excited atoms of the Yb:YAG crystal are stimulated by the photons of the multiple 2 ultrashort light pulses 2a and emit coherent photons therewith, increasing the intensity of the electromagnetic field and thus giving rise to the multiple 2 amplified ultrashort light pulses 2a. The ultrashort light pulses 2a are directed again by one or more second guiding elements 11, 12, 13 towards a semi-reflective mirror 14, which transmits a part of the energy of the multiple amplified ultrashort light pulses 2a and reflects the remaining part of the energy, which again goes through the previously described operating cycle.

[0086] This operating cycle is then repeated throughout the life of the light emitting laser device 3 .

[0087] Obviously, as already mentioned, many operating cycles are required for the light emitting laser device 3 to reach a stable phase of the pulsed state.

[0088] It should be noted that the non-limiting example of the operation described above refers to a light pulse 2a having a duration on the order of femtoseconds, and therefore it is the Gears-Tournois type mirror 13, as described above, that allows the achievement and sustainment of a light pulse 2a of this duration.

[0089] Therefore, the light emitting laser device 3 according to the present invention has a high repetition rate f r , each of the plurality of 2 ultrashort light pulses 2a having a high energy E p This is done while ensuring the operational stability and safety of all components of the light-emitting laser 3 device, with emphasis on mitigating Q-switching instabilities as much as possible.

[0090] As can be seen, the light-emitting laser arrangement 3 according to the invention can find advantageous use and advantageous implementation in an optoelectronic device for emitting a plurality 2 of packets 2b of ultrashort light pulses 2a with high energy and high repetition frequency. For this reason, the subject of the invention is also an optoelectronic device for emitting a plurality 2 of packets 2b of ultrashort light pulses 2a with high energy and high repetition frequency, which is shown in the attached figure under the reference number 1.

[0091] The optoelectronic device 1 comprises a light emitting laser device 3 according to the invention, a modulation means 4 configured to pick up and modulate a given number of light pulses 2 a from the plurality of ultrashort light pulses 2 a emitted by the light emitting laser device 3 so as to create a packet 2 b of modulated ultrashort light pulses 2 a, and a modulation means 4 positioned downstream of the modulation means 4 and configured to modulate an energy E p In particular, the amplification means 5 is arranged to amplify the energy E p to a value required, for example, by the operational application of the device 1.

[0092] The modulation means 4 may preferably be or comprise at least an acousto-optical modulator 4a, such as a tellurium dioxide crystal, and, if necessary, a driving means 4b, such as an electronic driver, operating at a fixed modulation frequency but with variable amplitude, designed to drive the at least one acousto-optical modulator 4a in accordance with the operational requirements of the device 1.

[0093] These operational requirements may, for example, require the temporary interruption of the emission or emission of the laser beam from the device 1 when this device 1 is used in a material micromachining operation such as the execution of a series of spaced holes or the engraving of a motif. In this regard, after the execution of a hole, the device 1 must suspend the laser output until the next hole or engraving position and at that particular point in time resume the laser output to make the next hole or engraving. Furthermore, considering that the device 1 is used in a material micromachining operation, another operational requirement may be to have a different evolution over time of the optical power of the optical pulses 2a of each packet 2b depending on the material being processed. For example, if the material is glass, it may be necessary to have a customized thermal gradient to prevent breakage.

[0094] The driving means 4b may be designed to drive the acousto-optical modulator 4a with a digital signal, e.g. a TTL signal, designed to activate or deactivate the acousto-optical modulator 4a, such that when deactivated the acousto-optical modulator allows the passage of the plurality of two optical pulses 2a, while when activated the acousto-optical modulator generates a packet 2b of modulated ultrashort optical pulses 2a by diverting the plurality of two optical pulses 2a towards the input of the amplifier 5a, and / or with an analog signal designed to modulate the amplitude and therefore the power of the packet 2b of optical pulses 2a in accordance with the operational requirements of the device 1.

[0095] In particular, the optical pulses 2a that are not deflected by the acousto-optical modulator 4a and therefore do not reach the input of the amplification means 5 can be dissipated by heat dissipation means, for example encountering a damper made of a metal element operatively associated with a heat sink, if necessary. Conversely, the optical pulses 2a that are deflected by the acousto-optical modulator 4a towards the input of the amplification means 5 are modulated.

[0096] In practice, the driving means 4b, more particularly an electronic driver, can control the amplitude of the multiple 2 ultrashort light pulses 2a entering the acousto-optical modulator 4a by means of an analog input voltage and / or a digital input signal, for example to perform on / off modulation of the device 1.

[0097] Each packet 2b is preferably composed of several light pulses 2a comprised between 50 and 1000, for example 500. This interval is optimal, considering the use of the optoelectronic device 1 in industrial applications of micromachining of materials as an example, since the materials are preferably operated in the so-called "ablation cooling regime", which sets a minimum threshold for the number of light pulses 2a in each packet 2b of the laser beam leaving the device 1 so that a fast and accurate removal of the material to be treated can be performed.

[0098] As regards the amplification means 5, said amplification means 5 receives at an input the packets 2b of ultrashort optical pulses 2a modulated by the modulation means 4 and amplifies them, for example to a value required by the operational application of the device 1.

[0099] In particular, the single stage amplifier 5a preferably reduces the energy E p to a value comprised between about 100 nJ and about 5 μj, for example between about 100 nJ and about 20 μj, so that the energy value of each packet 2b reaches up to a few mJ, for example, without limitation, between about 5 μj and about 5 mJ.

[0100] This single stage amplifier 5a preferably reduces the energy E p and a guiding element 5c.

[0101] In particular, the pump means 5b preferably includes at least one gain element 16 and at least one pump element 17 configured to emit at least one pump light beam PB2 during use, while the guide component 5c may preferably be configured to guide packets 2b of ultrashort light pulses 2a at the input to the amplifier 5a towards the gain element 16 and to guide packets 2b of ultrashort light pulses 2a amplified by the pump means 5b from the gain element 16 towards the output of the amplifier 5a.

[0102] The at least one gain element 16 may be or may comprise at least one ytterbium ion doped crystal of the Yb:YAG or Yb:CALGO type, having an emission wavelength of about 1020 nm to about 1080 nm and, optionally, a dopant ion concentration that may vary between 1% and 15%. The Yb:YAG or Yb:CALGO crystal may have, for example, a length of 3 mm to 20 mm and a rectangular or square cross section.

[0103] On the other hand, with regard to the at least one pump element 17, the pump element 17 may be or preferably comprises at least one laser diode configured to emit at least one pump light beam PB2 with a power of about 50 W to about 150 W and, optionally, with an emission wavelength of about 935 nm to about 985 nm.

[0104] According to the exemplary embodiment of the amplification means 5 shown in FIG. 4, the laser diode operates in the continuous wave or CW regime, ie, in use, provides a pump light beam PB2 that is continuous in time.

[0105] In particular, the at least one laser diode is preferably an optical fiber coupled laser diode terminated with a collimator so as to emit a pump light beam PB2 having a flat wavefront.

[0106] According to a non-limiting example of an embodiment of the device 1 according to the invention shown in the figures, the at least one gain element 16 is an ytterbium ion doped crystal of the Yb:YAG type, while the at least one pump element 17 is a laser diode configured to emit at least one pump light beam PB2 with a power of about 80 W.

[0107] The guide element 5c may preferably comprise at least a first guide element 18 adapted to guide packets 2b of ultrashort optical pulses 2a entering the amplifier 5a towards the gain element 16, and at least a second guide element 19 adapted to guide packets 2b of ultrashort optical pulses 2a amplified by the pump means 5b from the gain element 16 towards the output of the amplifier 5a.

[0108] Preferably, the amplification means 5 also comprises one or more focusing components 20, 21, 22 adapted to focus or collimate at least one pump light beam PB2 emitted by the pump element 17 and / or packets 2b of ultrashort light pulses 2a at the input to the amplifier 5a and / or packets 2b of ultrashort light pulses 2a amplified by the pump means 5b.

[0109] More specifically, the one or more focusing components 20, 21, 22 may be a first lens 20 adapted to focus the pump light beam PB2 emitted by the pump element 17 towards the gain element 16, and / or a second lens 21 adapted to focus the packet 2b of ultrashort light pulses 2a entering the amplifier 5a, and / or a third lens 22, such as a collimating lens adapted to collimate the packet 2b of ultrashort light pulses 2 amplified by the pump means 5b.

[0110] Alternatively, at least one of the first and second guide components 18, 19 may be or may comprise a dichroic mirror configured with a reflectivity of about 99% or more at the wavelength of the packet 2b of ultrashort light pulses 2a and a transmittance of about 95% or more at the wavelength of the pump light beam PB2 emitted by the pump element 17.

[0111] Furthermore, the amplifier 5a preferably operates according to a counter-propagating regime, i.e. the packet 2b of ultrashort light pulses 2a propagates collinearly with the pump light beam PB2 but in the opposite propagation direction, and / or in a diverging regime, i.e. the packet 2b of ultrashort light pulses 2a propagates in the gain element 16 with a divergence value so as to include an increase in light intensity due to the amplification process. In fact, the position of the focal point of the packet 2b of light pulses 2a to be amplified relative to the gain element 16 is optimized in order to maximize the spatial or volumetric overlap inside the gain element 16 between the packet 2b of ultrashort 2a light pulses and the pump light beam PB2.

[0112] Essentially, the spatial overlap or mode matching between the pump light beam PB2 and the packet 2b of light pulses 2a to be amplified can be advantageously optimized by focusing such a packet 2b of light pulses 2a whose focal point is located outside the gain element 16, for example via a second lens 21, so as to maintain optimal mode matching despite large differences in divergence between the pump light beam PB2 and the beam comprising the packet 2b of light pulses 2a to be amplified.

[0113] In particular, the second lens 21 can focus the packet 2b of light pulses 2a to be amplified at a focusing size having a diameter, for example, 1 / 20 to 1 / 5, relative to the size of the diameter of the pump light beam PB2 focused by the first lens 20 as necessary.

[0114] As can be seen, having a plurality 2 of highly energetic ultrashort optical pulses 2a at the output from the light emitting laser device 3 allows for a relaxation of the downstream amplification requirements, allowing packets 2b of optical pulses 2a to be amplified via only a single stage amplifier 5a, significantly reducing the overall cost and architectural complexity of the optoelectronic device 1.

[0115] A non-limiting example of the operation of the optoelectronic device 1 will now be described according to the example embodiment shown in the figures.

[0116] The light emitting laser device 3 generates and transmits at its output a plurality 2 of high energy ultrashort light pulses 2a at a high repetition rate, for example according to the operation described above. This plurality 2 enters the modulation means 4, or more specifically the acousto-optical modulator 4a, which is driven by the driving means 4b according to the application requirements to generate packets 2b of modulated ultrashort light pulses 2a and divert them towards the input of the single-stage solid-state amplifier 5a. The packets 2b of light pulses 2a entering the amplifier are first focused through the second lens 21 and then reflected by the first guiding element 18 towards the Yb:YAG crystal 16. This Yb:YAG crystal 16 is pumped via the pump light beam PB2 emitted by the laser diode 17 and is focused into the gain element 16 via the first lens 20 according to the counter-propagating operating regime. Naturally, the pump light beam PB2 can pass through the second guiding element 19, since it is made with high transmission at the emission wavelength of the latter. The pump light beam PB2 directed towards the Yb:YAG crystal 16 excites the atoms of the Yb:YAG crystal 16, which, when struck or stimulated by the photons of the packet 2b of the light pulse 2a, emit photons coherent with them, increasing the intensity of the electromagnetic field and thus the packet 2b of the amplified ultrashort light pulse 2a. Such packet 2b of the amplified ultrashort light pulse 2a at the output of the Yb:YAG crystal 16 is first reflected by the second guide element 19 and then collimated by the third lens 22 towards the output of the amplifier 5a, so that the size of the laser beam output does not change appreciably even over a considerable propagation distance.

[0117] Furthermore, the object of the invention is also a method for emitting a plurality 2 of packets 2b of ultrashort light pulses 2a at high energy and high repetition frequency.

[0118] The method according to the invention first comprises the step of providing a device 1 according to the invention or according to an embodiment of the invention.

[0119] Next, the light emitting laser device 3 emits a high energy E pand high repetition frequency f r There is a step of emitting a plurality 2 of ultrashort light pulses 2a accompanied by

[0120] Thereafter, a step is envisaged of picking up and modulating a given number of light pulses 2a from the plurality 2 of ultrashort light pulses 2a emitted by the light emitting laser device 3 by a modulation means 4 so as to generate a packet 2b of modulated ultrashort light pulses 2.

[0121] In particular, this step of picking up and modulating may comprise driving an acousto-optical modulator 4a of the modulating means 4 by driving means 4b, for example via a digital and / or analogue signal.

[0122] Finally, the method provides for amplifying the packets 2b of modulated ultrashort optical pulses 2a by means of amplification means 5.

[0123] The light emitting laser device 3 allows for a safe and highly operationally stable emission of a plurality of light pulses 2a with high energy and high repetition frequency.

[0124] The optoelectronic device 1 provides an alternative and innovative solution for a wide variety of industrial, scientific, and / or medical operational applications at a lower overall cost and lower architectural complexity than known ultrashort pulse laser devices based on low power oscillators and multi-stage amplifiers using Chirped Pulse Amplification or CPA technology.

[0125] Furthermore, the optoelectronic device 1 also allows for good precision and processing speed and therefore good overall operating quality when used for example in micromachining or microsoldering of materials.

[0126] The optoelectronic device 1 according to the present invention should also be considered to have high scalability, since it may be possible to add amplification means 5, more specifically single stage amplifiers 5a, in cascade, to reach higher energy or power at its output, as necessary or desired, to achieve the power or energy requirements required by the application in question.

[0127] Furthermore, the optoelectronic device 1 according to the present invention does not require the implementation of stretchers and compressors, which represents an inherent savings both in terms of cost and in terms of architectural complexity.

[0128] It can thus be seen how the invention perfectly achieves the proposed objectives.

[0129] The invention thus conceived is susceptible to modifications and variations, all of which are within the scope of the inventive concept.

[0130] Moreover, all the details may be replaced with other technically equivalent elements.

[0131] In fact, the materials used, as well as the conditional shapes and dimensions, may be any according to requirements, without waiving the scope of protection of the following patent claims.

Claims

1. A laser device (3) for emitting a plurality (2) of ultrashort light pulses (2a) with high energy and high repetition rate, i.e., each light pulse (2a) having a duration on the order of about 10 picoseconds to about 10 femtoseconds, said light emitting laser device (3) being or comprising at least one solid-state laser oscillator (3a) operating in a passive mode-locked operation mode in use, and having a repetition rate (f) of about 500 MHz or higher. ｒ ), each light pulse (2a) of the plurality (2) of ultrashort light pulses (2a) having an energy value (E) of about 2 nJ to about 20 nJ. ｐ ) The oscillator (3 a) is adapted to generate at least one optical light source that is designed to be switched or converted, in use, first into resonant light and then into a plurality (2) of ultrashort light pulses (2 a), and thereafter to measure the energy (E ｐ ) and pumping means (3b) adapted to amplify the at least one gain means (6) and, in use, at least one pumping light beam (PB １ and at least one pumping element (7) configured to emit a laser (3a) or an optical light source, the oscillator (3a) laser also comprising a resonant cavity (RC), the resonant cavity (RC) comprising: - directing the plurality (2) of ultrashort optical pulses (2a) or the resonant light towards the gain means (6); - directing said plurality (2) of ultrashort optical pulses (2a) or resonant light from said gain means (6) towards the output of said resonant cavity (RC) and vice versa, where said ultrashort optical pulses (2a) or resonant light are amplified by said pumping means (3b); and a guide means (3c) configured as follows: the resonant cavity (RC) is configured such that the focal point of the resonant light is located within a specific distance range outside one of the at least two faces of the gain means (6) intersected by the resonant light, in order to keep its dimension, i.e., the width of the beam along its extension, substantially constant while the light-emitting laser device (3) transitions from a continuous wave state to a pulsed state. Light emitting laser device (3).

2. 2. The light emitting laser device (3) of claim 1, wherein the at least one gain means (6) is or comprises at least one ytterbium ion doped crystal of the YAG or CALGO type having an emission wavelength comprised between approximately 1020 nm and approximately 1080 nm.

3. The at least one pumping element (7) pumps the at least one pumping light beam (PB) with a power of about 5 W to about 20 W. １ 2. The light emitting laser device (3) of claim 1, which is or comprises at least one laser diode configured to emit a light beam.

4. The laser diode emits a pumping light beam (PB) with a flat wavefront. １ 4. The laser emitting device (3) of claim 3, wherein the laser is an optical fiber coupled laser diode terminated with a collimator so as to emit a laser beam.

5. The guiding means (3c) one or more first directing elements (8, 9, 10) adapted to direct the resonant light in said resonant cavity (RC) or said plurality (2) of ultrashort light pulses (2a) towards said gain means (6); one or more second guiding elements (11, 12, 13, 14) adapted to guide the resonant light in the resonant cavity (RC) or the plurality (2) of ultrashort light pulses (2a), amplified by the pumping means (3b), from the gain means (6) towards the output of the resonant cavity (RC) and vice versa; The laser emitting device (3) according to claim 1, comprising:

6. 6. The light-emitting laser device (3) according to claim 5, wherein at least one of the one or more first directing elements (8, 9, 10) is or comprises at least a conversion means (8a) adapted to convert the optical light source emitted by the at least one pumping element (7) into a plurality of ultrashort light pulses (2a) and then direct the plurality of ultrashort light pulses (2a) towards the gain means (6).

7. 7. The light-emitting laser device (3) of claim 6, wherein the conversion means (8a) comprises a nonlinear mirror including a saturable absorber or SESAM or a nonlinear crystal configured to generate a second harmonic when in use, and a dichroic mirror used in combination with the nonlinear crystal and configured with a reflectivity of about 99% or more at green wavelengths and a reflectivity of about 95% or more at the wavelengths of the plurality (2) of ultrashort light pulses (2a).

8. The one or more first guide elements (8, 9, 10) may comprise a mirror (9) configured with a reflectivity of about 99% or more at the wavelength of the plurality (2) of ultrashort optical pulses (2 a), and / or a mirror (9) configured with a reflectivity of about 99% or more at the wavelength of the plurality (2) of ultrashort optical pulses (2 a), and configured with a reflectivity of about 99% or more at the wavelength of the plurality (2) of ultrashort optical pulses (2 a), and configured to reflect the pumping light beam (PB) emitted by the pumping element (7). １ 6. The light emitting laser device (3) according to claim 5, wherein the light emitting laser device (3) is or comprises a dichroic mirror (10) configured with a transmittance of about 95% or more at the wavelength of .

9. 6. The light-emitting laser device (3) according to claim 5, wherein the one or more second inductive elements (11, 12, 13, 14) are or comprise at least one reflective and transmissive element or coupler (14) configured to enable transmission of a first portion of the energy of the resonant light in the resonant cavity (RC) or the plurality of (two) ultrashort optical pulses (2 a) amplified by the pumping means (3 b) to an output of the oscillator (3 a), and feedback or reflection of a second portion of the energy of the resonant light in the resonant cavity (RC) or the plurality of (two) ultrashort optical pulses (2 a) amplified by the pumping means (3 b) back into the resonant cavity (RC).

10. 10. The light emitting laser device (3) of claim 9, wherein the at least one reflective and transmissive element or coupler (14) is or comprises a semi-reflective mirror configured with a partial reflectivity of about 75% to about 95% at the wavelength of the plurality (2) of ultrashort light pulses (2 a).

11. The one or more second inductive elements (11, 12, 13, 14) have a reflectivity of about 99% or more at the wavelength of the plurality (2) of ultrashort light pulses (2a) and the pumping light beam (PB) emitted by the pumping element (7). １ 6. The light emitting laser device (3) according to claim 5, comprising or at least a first dichroic mirror (11) configured with a transmittance of about 95% or more at the wavelength of the plurality of (2) optical pulses (2 a), and / or a second mirror (12) configured with a reflectance of about 99% or more at the wavelength of the plurality of (2) optical pulses (2 a), and / or a third mirror (13) of the Gears-Tournois type configured to support soliton generation within the resonant cavity (RC).

12. The pumping means (3b) is adapted to pump the at least one pumping light beam (PB) emitted by the pumping element (7). １ ) towards said gain means (6), said at least one focusing element (15) being adapted to focus a pump light beam (PB) having a diameter dimensionally matching a resonant mode supported by said resonant cavity (RC) in said gain means (6). １ ) emitted by the pumping element (7) to obtain the at least one pumping light beam (PB １ 2. The light emitting laser device (3) of claim 1, wherein the lens is configured to focus the laser beam onto the gain means (6).

13. 2. The light-emitting laser device (3) of claim 1, wherein the resonant cavity (RC) is configured such that a focus of the resonant light is located at a distance in a range of about 5 mm to about 30 mm from one of the at least two faces of the gain means (6) intersected by the resonant light.

14. An optoelectronic device (1) for emitting a plurality (2) of packets (2b) of ultrashort light pulses (2a) with high energy and high repetition frequency, comprising a light emitting laser device (3) according to claim 1, a modulation means (4) configured to pick up and modulate a given number of light pulses (2a) from the plurality (2) of ultrashort light pulses (2a) emitted by the light emitting laser device (3) to generate a packet (2b) of modulated ultrashort light pulses (2a), and a modulation means (4) arranged downstream of the modulation means (4) for modulating the energy (E) of each light pulse (2a) of the packet (2b) of ultrashort light pulses (2a) modulated by the modulation means (4). ｐ and an amplifier (5) configured to amplify the energy (E) of each light pulse (2a) of each packet (2b), ｐ an optoelectronic device (1) comprising or including at least one single-stage amplifier (5a) configured to amplify a

15. 15. The device (1) according to claim 14, wherein the modulation means (4) is or comprises at least one acousto-optic modulator (4a) and driving means (4b) adapted to drive the acousto-optic modulator (4a) based on the operating requirements of the device (1).

16. 16. The device (1) according to claim 15, wherein the acousto-optic modulator (4a) is or comprises a tellurium dioxide crystal.

17. The driving means (4b) by a digital signal designed to activate or deactivate the acousto-optical modulator (4a), such that when deactivated the acousto-optical modulator (4a) allows the passage of the plurality (2) of optical pulses (2a) while when activated it diverts the plurality (2) of optical pulses (2a) towards the input of the amplifier (5a) thereby generating packets (2b) of modulated ultrashort optical pulses (2a), and / or by an analogue signal designed to modulate the amplitude and therefore the power of the packets (2b) of optical pulses (2a) according to the operational requirements of the device (1), 16. The device (1) according to claim 15, designed to drive the acousto-optic modulator (4a).

18. The single stage amplifier (5a) amplifies the energy (E ｐ 15. The device (1) of claim 14, configured to amplify a current of about 100 nJ to about 20 μj.

19. The amplifier (5a) The energy (E ｐ ), the pump means (5b) being adapted to amplify the at least one pump light beam (PB2), the pump means (5b) comprising at least one gain element (16) and at least one pump element (17) configured, in use, to emit at least one pump light beam (PB2); - guiding said packets (2b) of ultrashort optical pulses (2a) at the input of said amplifier (5a) towards said gain element (16); and - directing said packets (2b) of ultrashort optical pulses (2a) amplified by said pump means (5b) from said gain element (16) towards the output of said amplifier (5a); a guide component (5c) configured as follows:

15. The device (1) according to claim 14, which is a solid-state amplifier comprising:

20. 20. The device (1) according to claim 19, wherein the at least one gain element (16) is or comprises at least one ytterbium ion doped crystal of the YAG or CALGO type having an emission wavelength comprised between about 1020 nm and about 1080 nm.

21. 20. The device (1) of claim 19, wherein the at least one pump element (17) is or comprises at least one laser diode configured to emit the at least one pump light beam (PB2) with a power in the range of about 50 W to about 150 W.

22. The guide element (5c) - at least a first guiding element (18) adapted to guide packets (2b) of ultrashort optical pulses (2a) input to said amplifier (5a) towards said gain element (16); at least a second guiding element (19) adapted to guide the packets (2b) of ultrashort optical pulses (2a) amplified by said pumping means (5b) from said gain element (16) towards the output of said amplifier (5a); 20. The device (1) according to claim 19, comprising:

23. The amplifying means (5) amplifies the at least one pump light beam (PB) emitted by the at least one pump element (17). ２ 2. The device (1) according to claim 1, further comprising one or more focusing elements (20, 21, 22) adapted to focus or collimate a packet (2b) of ultrashort light pulses (2a) input to the amplifier (5a) and / or a packet (2b) of ultrashort light pulses (2a) amplified by the pump means (5b).

24. The first and second guide elements (18, 19) have a reflectivity of about 99% or more at the wavelength of the packet (2b) of ultrashort optical pulses (2a) and a reflectivity of the pump light beam (PB) emitted by the pump element (17). ２ 23. The device (1) according to claim 22, which is or comprises a dichroic mirror configured with a transmittance of about 95% or more at wavelengths of 1000 nm to 1000 nm.

25. The one or more focusing components (20, 21, 22) focus the pump light beam (PB) emitted by the at least one pump element (17). ２ 24. The device (1) according to claim 23, wherein the amplifier (5a) comprises a first lens (20) adapted to focus the packet (2b) of ultrashort light pulses (2a) input to the amplifier (5a) and / or a second lens (21) adapted to focus the packet (2b) of ultrashort light pulses (2a) input to the amplifier (5a) and / or a third lens (22) adapted to collimate the packet (2b) of ultrashort light pulses (2a) amplified by the pump means (5b).

26. The second lens (21) directs the smaller divergence of the packet (2b) of light pulses (2a) to the pump light beam (PB ２ The pump light beam (PB) is focused by the first lens (20) to match the much larger divergence of the pump light beam (PB). ２ 26. The device (1) according to claim 25, wherein the packet (2b) of light pulses (2a) is focused with a focus size having a diameter of 1 / 20 to 1 / 5 of a focus size of a diameter of 1 / 20 to 1 / 5.

27. The at least one amplifier (5a) operates according to the counter-propagation regime, i.e. the packets (2b) of ultrashort optical pulses (2a) are fed to the pump light beam (PB ２ 20. The device (1) according to claim 19, wherein the packets (2b) of ultrashort optical pulses (2a) propagate in the gain element (16) collinearly but in an opposite propagation direction to the packets (2b) of ultrashort optical pulses (2a) and / or in a divergent manner, i.e. the packets (2b) of ultrashort optical pulses (2a) propagate in the gain element (16) with a divergence value so as to include an increase in optical intensity due to the amplification process.

28. 1. A method for emitting multiple (2) packets (2b) of ultrashort light pulses (2a) with high energy and high repetition rate, comprising: Providing a device (1) according to claim 16; High energy (E ｐ ) and high repetition frequency (f ｒ emitting a plurality (2) of ultrashort light pulses (2a) with picking up and modulating, by said modulation means (4), a determined number of light pulses (2 a) from said plurality (2) of ultrashort light pulses (2 a) emitted by said light emitting laser device (3) so as to generate a packet (2 b) of modulated ultrashort light pulses (2 a); amplifying said packets (2b) of modulated ultrashort optical pulses (2a) by said amplifier means (5); A method comprising:

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