阅读说明：本技术 用于生成在空间上定位的高强度激光束的系统和方法 (System and method for generating a spatially positioned high intensity laser beam ) 是由 F·佐默 P·费维尔 A·库尧德 于 2018-11-20 设计创作，主要内容包括：本发明涉及一种用于产生在空间上定位的高强度激光束的系统,它包括：适于产生N个激光脉冲的连发的激光源(80),所述N个激光脉冲具有小于或等于1皮秒的持续时间并具有大于或等于0.5吉赫的第一重复频率(f<Sub>1</Sub>)；适于接收和存储所述N个激光脉冲的连发光学谐振腔(10),该光学谐振腔(10)适于将所述N个激光脉冲的连发聚焦到所述光学谐振腔(10)的相互作用区域(25)；以及伺服控制系统(13),该伺服控制系统适于相对于光学谐振腔中的往返距离来控制第一重复频率(f<Sub>1</Sub>),以使所述连发的N个脉冲在相互作用区域(25)中通过相长干涉在时间上和空间上相互叠加,以形成超短且高能量的巨脉冲。(The invention relates to a system for generating a spatially positioned high intensity laser beam, comprising: a laser source (80) adapted to generate bursts of N laser pulses having a duration less than or equal to 1 picosecond and having a first repetition frequency (f) greater than or equal to 0.5 gigahertz 1 ) (ii) a A burst optical resonator (10) adapted to receive and store said N laser pulses, the optical resonator (10) being adapted to excite said N laser pulses-the burst of light pulses is focused to an interaction region (25) of the optical resonator (10); and a servo control system (13) adapted to control the first repetition frequency (f) with respect to a round trip distance in the optical cavity 1 ) So that the successive N pulses overlap each other temporally and spatially by constructive interference in the interaction region (25) to form ultrashort and high-energy giant pulses.)

1. A system for generating a spatially localized high intensity laser beam, the system comprising:

-a laser source (80) adapted to generate bursts of N laser pulses, where N is a natural integer greater than 1, said N laser pulses having a first repetition frequency (f;)₁) The laser pulses are ultrashort laser pulses having a duration of less than or equal to 1 picosecond, the first repetition frequency (f)₁) Greater than or equal to 0.5 gigahertz,

-an optical resonator (10) adapted to receive and store said burst of N laser pulses, the optical resonator (10) being adapted to focus said burst of N laser pulses onto an interaction region (25) of the optical resonator (10), a round trip distance inside the optical resonator being equal to c/f₁Where c is the speed of light, and

-a servo control system (13) adapted to control said first repetition frequency (f) with respect to a round trip distance in said optical resonator₁) So that said N pulses of said burst temporally and spatially overlap each other in said interaction region (25) by constructive interference to form a giant pulse of ultrashort and high energy.

2. System according to claim 1, wherein the laser source comprises an oscillator (1) with a first repetition frequency (f) higher than or equal to 1GHz₁) And (4) transmitting.

3. The system of claim 1, wherein the laser source (80) comprises a regenerative amplifier having a primary optical cavity; and wherein the servo control system (13) is adapted to adjust the length of the primary optical cavity in order to control the first repetition frequency (f)₁)。

4. System according to any one of claims 1 to 3, wherein the laser source (80) comprises a pulse selector (3) adapted to select a second repetition frequency (f) lower than or equal to 4MHz₂) N ultrashort lasersAnd (5) repeating the pulse.

5. The system of any of claims 1 to 4, wherein the optical resonant cavity comprises mirrors (M1, M2, M3, M4) arranged in a planar configuration.

6. The system according to any one of claims 1 to 5, wherein the optical resonance cavity (10) is arranged in a vacuum chamber (8) comprising at least one opening (9) adapted to receive a burst of N ultrashort laser pulses, the at least one opening (9) being adapted to receive a charged particle beam (40), the optical resonance cavity (10) being arranged to propagate the charged particle beam (40) in an interaction region (25) at an angle of incidence less than or equal to 5 ° with respect to a propagation direction of the burst of laser pulses in the interaction region (25).

7. Raman spectroscopy device comprising a system according to any one of claims 1 to 6, wherein said interaction region (25) is intended to receive a sample to be analyzed, said raman spectroscopy device comprising a raman spectrometer arranged to measure a raman scattered beam formed by scattering said ultrashort giant pulse on the sample of the interaction region (25).

8. A method for generating a spatially positioned high intensity laser beam, the method comprising the steps of:

-at a first repetition frequency (f)₁) Generating laser pulses having a duration of less than or equal to 1 picosecond, the first repetition rate being greater than or equal to 0.5 gigahertz,

-selecting at a first repetition frequency (f)₁) Wherein N is a natural integer greater than or equal to 1;

-injecting bursts of said N laser pulses into an optical resonator (10), the optical resonator (10) having a value equal to c/f₁Wherein c is the speed of light in an optical cavity, said optical cavity (10) being adapted to aggregate said bursts of N laser pulsesAn interaction region (25) focused to the optical resonator (10); and

-controlling a first repetition frequency (f) with respect to a round trip distance of the optical resonator (10)₁) So that the consecutive N pulses are superimposed on each other temporally and spatially by constructive interference in the interaction region (25), thereby forming ultrashort and high-energy giant pulses.

9. A method for measuring inelastic scattering by interacting an ultrashort giant pulse generated by the method according to claim 8 with a charged particle beam propagating in synchronism with the ultrashort giant pulse in the interaction region (25) of the optical resonator (10).

10. A method for measuring inelastic scattering by interacting an ultrashort giant pulse generated by the method of claim 8 with a sample placed in an interaction region (25) of the optical resonator (10).

Technical Field

The present invention relates generally to the field of lasers.

More particularly, the present invention relates to a laser system that produces a very high intensity laser beam positioned at a point in space.

The invention also relates to a very high intensity laser system intended to interact at an anchor point by inelastic scattering with a charged particle beam or a sample to be analyzed.

More particularly, the present invention relates to a method and apparatus for measuring inverse compton scattering resulting from interaction between a laser beam and a charged particle beam.

Background

Particle accelerators are great scientific instruments used, in particular, in basic physics. New applications of these particle beams are sought to be developed in the field of scientific instruments or medical devices. These applications require the development of high intensity and compact X-ray sources for use in, for example, medical or artistic history environments.

In particular, it is sought to generate inverse compton scattered radiation based on compton interaction between the electron packet and the laser beam. The intensity of the radiation generated by inelastic scattering now depends both on the number of photons and on the number of electrons upon interaction. Furthermore, the intensity of the inverse compton scattered radiation is not isotropically distributed. In practice, the intensity of the inverse compton scattered radiation is highly dependent on the angle between the electron beam and the laser beam and/or the angle between the incident laser beam and the scattered beam. Therefore, it is sought to maximize the intensity of the detected inverse compton scattered radiation.

The use of different types of accelerators, of the linear or circular type, for generating low-energy electron packets (of the order of 50 MeV) can be considered. The storage ring has an advantageous configuration due to its compactness, low cost and ease of use. Compactness and low energy present challenges in the selection of particle accelerators and coupling configurations between particle beams and laser beams.

An ELI-NP-GS source is known that uses an optical recycler that includes two parabolic mirrors and 31 pairs of spirally arranged mirrors to cycle the same 200-mJ laser pulse 32 times. Thus, this 200-mJ laser pulse interacts sequentially with 32 electronic packets generated at a rate of 100Hz at the same focal point. However, this type of optical recycler is bulky. Furthermore, the provision of 64 mirrors in a vacuum chamber is particularly complicated.

Systems also exist for coupling a laser beam to a fabry-perot cavity to amplify a steady state laser beam.

In general, it is desirable to have a high intensity laser system positioned at a certain point.

More particularly, it is sought to develop a system for the interaction between a charged particle beam and a high-intensity laser beam, which is easy to implement and which is able to increase the intensity of the inelastically scattered beam by the inverse compton effect resulting from this interaction.

Disclosure of Invention

To remedy the above-mentioned deficiencies of the prior art, the present invention proposes a system for generating a spatially positioned high-intensity laser beam.

More specifically, according to the invention, a system is proposed which comprises: a laser source adapted to generate N laser pulsesBurst of bursts, where N is a natural integer greater than 1, the N laser pulses having a first repetition frequency (f)₁) The laser pulses are ultrashort laser pulses having a duration of less than or equal to 1 picosecond, the first repetition frequency (f)₁) Greater than or equal to 0.5 gigahertz (gigahertz); an optical resonator adapted to receive and store said burst of N laser pulses, the optical resonator being adapted to focus (focus) said burst of N laser pulses to an interaction region of the optical resonator, a round trip distance within the optical resonator being equal to c/f₁Where c is the speed of light; and a servo control system adapted to control a first repetition frequency (f) with respect to a round trip distance in said optical cavity₁) So that the N pulses in the burst overlap each other temporally and spatially by constructive interference in the interaction region, thereby forming an ultra-short and high-energy giant pulse.

The system allows to generate a defined interaction region, the laser beam having a very high intensity, the duration of the laser pulse being extremely short and having a power multiplied by about N times by the optical cavity.

Preferably, N is a natural integer between 10 and 1000, and more preferably, it is between 100 and 300.

In a particular embodiment, the laser source comprises a first repetition rate (f)₁) A transmitting oscillator.

In another particular embodiment, the laser source comprises a regenerative amplifier, preferably of the optical fiber type, wherein the optical amplifier comprises a primary optical cavity and the servo control system is adapted to adjust the length of said primary optical cavity in order to control said first repetition frequency (f)₁)。

Preferably, the first repetition frequency (f)₁) Higher than or equal to 1GHz (gigahertz).

Advantageously, the laser source comprises a pulse selector adapted to select a second repetition frequency (f) less than or equal to 4MHz₂) Of N ultrashort laser pulsesAnd (4) sending.

Preferably, the optical resonator comprises mirrors arranged in a planar configuration (arranged in a plane).

According to a particular and advantageous embodiment, the optical resonator comprises two spherical mirrors and two plane mirrors, which are arranged in a planar configuration.

According to a variant, the optical resonator comprises two spherical mirrors and only one flat mirror.

Advantageously, the optical resonator comprises a first concave spherical mirror (M3) having a radius of curvature R/2, a second concave spherical mirror (M4) having a radius of curvature R/2, said first concave spherical mirror (M3) and said second concave spherical mirror (M4) being arranged concentrically, the distance between the first concave spherical mirror (M3) and the second concave spherical mirror (M4) being equal to R.

According to a particular aspect, the servo control system comprises a detector adapted to detect a signal representative of constructive interference of consecutive N pulses in the optical cavity.

According to one embodiment, an optical resonance cavity is arranged in a vacuum chamber comprising at least one opening adapted to receive a burst of N ultrashort laser pulses, said at least one opening being adapted to receive a charged particle beam, said optical resonance cavity being arranged such that said charged particle beam propagates in an interaction region at an angle of incidence less than or equal to 5 ° with respect to a propagation direction of the burst of laser pulses in said interaction region.

It is particularly advantageous that the volume of the optical resonator is less than several dm³Preferably less than 1dm³。

The invention also proposes a raman spectroscopy device comprising a system for generating a spatially localized high intensity laser beam in which the interaction region is intended to receive a sample to be analyzed, said raman spectroscopy device comprising a raman spectrometer arranged to measure a raman scattered beam formed by scattering of said ultrashort giant pulse on the sample of the interaction region.

The invention also proposes a method for generating a spatially positioned high-intensity laser beam, comprising the steps of:

-at a first repetition frequency (f)₁) Generating laser pulses having a duration of less than or equal to 1 picosecond, the first repetition rate being greater than or equal to 0.5 gigahertz,

-selecting at said first repetition frequency (f)₁) Wherein N is a natural integer greater than or equal to 1;

-injecting bursts of said N laser pulses into an optical resonator having a value equal to c/f₁Wherein c is the speed of light in an optical cavity adapted to focus bursts of said N laser pulses onto an interaction region of the optical cavity; and

-controlling the first repetition frequency (f) with respect to the round trip distance of the optical cavity₁) Such that the N pulses in the burst temporally and spatially overlap each other by constructive interference in an interaction region, thereby forming ultrashort and high-energy giant pulses.

The invention also proposes a method for measuring inelastic scattering by interacting an ultrashort giant pulse generated by the method according to the invention with a charged particle beam propagating in synchronism with said ultrashort giant pulse in the interaction region of the optical resonator.

Finally, the invention proposes a method for measuring inelastic scattering by interacting the ultrashort giant pulse generated by the method according to the invention with a sample placed in the interaction region of the optical resonator.

Drawings

The description that follows, given by way of non-limiting example with reference to the accompanying drawings, will allow a good understanding of what and how the invention may be carried into effect.

In the drawings:

fig. 1 schematically shows an ultrashort giant laser pulse generation system according to the invention;

figure 2 schematically shows a perspective view of a vacuum chamber comprising an optical resonant cavity according to an embodiment;

FIG. 3 schematically shows a perspective view of the arrangement of the mirror frame of the optical resonator of FIG. 2;

figure 4 shows an example of a mirror frame with fine precision adjustment;

FIG. 5 schematically shows an exemplary embodiment of an arrangement of mirror frames forming optical resonant cavities with 4 mirrors in a coplanar arrangement;

FIG. 6 schematically shows in perspective view the coupling of a charged particle beam with an ultrashort and high-energy giant laser pulse focused at one point of a four-mirror optical resonant cavity to form an inverse Compton scattered beam;

FIG. 7 schematically shows another view of the interaction between a charged particle beam and a high-energy pulsed laser beam in a four-mirror optical resonant cavity to form an inverse Compton scattered beam;

FIG. 8 shows a variant of a three-mirror optical resonator;

fig. 9 schematically shows an ultrashort giant laser pulse generation system according to a variant of the invention.

Detailed Description

An ultrashort laser macropulse generation system is shown in fig. 1.

In this context, "ultrashort pulses" refer to optical pulses of duration typically between 20fs and about 10ps and with a spectral width of 0.1 to 50 nm.

The system of fig. 1 includes a laser source 80 adapted to generate bursts of ultra-short and high-energy laser pulses, in conjunction with the optical resonator 10 and a feedback loop control system.

In one embodiment, the laser source 80 includes a pulse type oscillator 1, a beam splitter 2, a pulse selector 3, an optical amplification system 4, a beam combiner 5, a mirror 6, and a mirror 7. The oscillator 1 is based on a tunable laser cavity. The oscillator 1 is adapted to operate at a first repetition frequency f₁A source pulse 100 is generated. Advantageously, the first repetition frequency is higher than or equal to 500MHz, and preferably higher than or equal to 1GHz, or even several gigahertz. According to a first repetition frequency f₁The source pulses 100 are spaced from each other by a time interval between 0.3ns and 2nsAnd (4) separating.

The beam splitter 2 and the beam combiner 5 are for example of the polarization beam splitter cube type. In this example, the source pulse 100 is polarized, for example linearly polarized, at the outlet of the oscillator 1. The beam splitter 2 is arranged and oriented to spatially split the source pulsed beam 100 into a pulsed beam 110 and a further pulsed beam 120. The pulsed beam 110 is reflected on the mirrors 6, 7 and has a first repetition frequency f₁A low power pulse beam 110 is formed.

The pulse selector 3 is for example based on an electro-optical modulator. The pulse selector 3 receives the other pulse beam 120 from the oscillator 1 and selects a burst of N source pulses, where N is a natural integer greater than 1, preferably between 25-10000, and more preferably between 100-. Advantageously, the pulse selector 3 has a second repetition frequency f less than or equal to 4MHz₂And (5) operating. Alternatively, the pulse selector 3 may also be operated by selecting a single pulse burst. In the same burst of N pulses, the pulses are repeated by a first repetition frequency f₁The determined time intervals are spaced apart.

The optical amplification system 4 comprises one or more optical amplifiers arranged in series. The optical amplification system 4 may be based on optical fibers, disks and/or solid state amplifiers. The optical amplification system 4 receives the bursts of N pulses and amplifies them to form bursts of N high power optical pulses. Thus, the optical amplification system 4 delivers a high power pulse beam 120 consisting of a burst of N pulses, typically at a second repetition frequency f₂And (4) transmitting.

According to a variant, instead of a high-frequency pulsed oscillator and one or more linear optical amplifiers, the laser source 80 comprises a regenerative amplifier, preferably of the optical fiber type. Preferably, in this example, the regenerative amplifier comprises an optical regenerative cavity for a repetition period T₁Means for injecting a source pulse in the optical regeneration chamber, and means for extracting the laser pulse from the optical regeneration chamber. In this example, the optical recycling cavity exhibits a total length such that the round-trip duration of each pulse in said optical recycling cavity is at period T₁Is between N-1 and N times, where N is an integer greater than or equal to 2, said injection device being suitable forThe extraction means is adapted to extract the burst of N laser pulses in the regenerative optical cavity upon capturing the burst of N laser pulses in the regenerative optical cavity, the optical amplifier medium being adapted to form an amplified burst of laser pulses. Advantageously, the injection means and the extraction means comprise a pockels cell configured to completely block the injection of the pulse train and the extraction of the pulse train. Preferably, the optical regeneration chamber is a multipass chamber in which the amplifier medium is arranged such that a pulse of the plurality of pulses makes multiple passes through the amplifier medium in succession. Advantageously, the optical regeneration chamber is a multi-channel chamber comprising an optical system whose mirrors are arranged such that an incident light beam on each of said mirrors is spatially offset at each channel in said multi-channel chamber, and the amplifier medium is arranged within the optical regeneration chamber.

It is thus possible to obtain a laser source that generates a burst of N ultrashort and high-power laser pulses, the pulses in the same burst being at a first repetition frequency f₁The first repetition frequency is greater than or equal to 0.5 gigahertz (GHz), and preferably greater than or equal to 1 GHz.

Hereinafter, the following terms are used synonymously: pulse train, pulse sequence, pulse train or macropulse(s).

The beam combiner 5 is arranged and oriented so as to be at a first repetition frequency f₁Is spatially recombined with a high power pulse beam 120 consisting of a burst of N pulses into a light pulse beam 150.

The light pulse beam 150 is injected into the vacuum chamber 8 comprising the optical cavity through the opening 9.

Fig. 2 to 7 show in detail a four-mirror optical resonator according to a first embodiment of the present invention.

The optical cavity 10 includes two plane mirrors M1, M2 and two spherical mirrors M3, M4. The mirrors M1, M2, M3, M4 are arranged in a planar configuration at the ends of an elongated quadrilateral. The mirrors M3 and M4 are arranged in a concentric configuration and preferably have the same radius of curvature R/2, the distance between the mirrors M3 and M4 being equal to R. Pulse beam 150 passes through plane mirror M1 is injected into the optical cavity and then proceeds toward mirror M2, which is reflected by mirror M2 to spherical mirror M3. Mirror M3 reflects pulsed beam 150 toward M4 while focusing the pulsed beam to an interaction region 25 located on the optical axis between mirror M3 and mirror M4. The mirror reflects pulsed beam 150 toward mirror M1 to form a closed loop optical path. Thus, the optical resonant cavity 10 allows the pulsed beam 150 to propagate behind the X-shaped folded ring (see fig. 7-8). The total length of the round trip in the optical cavity is adjusted so that N pulses of the same burst add coherently to each other by constructive interference to form a giant pulse in the optical cavity. In addition, the optical cavity 10 focuses the giant pulse to the interaction region 25, for example to the focal plane 20 located between mirrors M3 and M4. The giant pulse is cycled N times in the chamber at GHz rate. The optical cavity 10 is pulsed at a burst rate, i.e., a second repetition frequency f₂-filled and emptied.

The giant pulse has the same duration as the laser pulse of the laser source.

For a burst of N ≈ 2000 pulses with a duration of about 200fs, and an energy per source pulse of about 20-30mJ, an intensity of about 10 may be obtained in the interaction region 25¹⁵W/cm²Of (2) is performed. The transverse dimension of the waist of the laser beam is about 30 microns. Thus, the energy of the burst is stored at the interaction point. Furthermore, the giant pulses may be repeated in the same interaction region 25 at a second repetition frequency. Thus, it can interact with the giant laser pulse multiple times.

According to a first repetition frequency f₁The optical path length during round trips in the optical cavity 10 is determined. More precisely, the round-trip length is equal to c/f₁Where c is the speed of light in the optical cavity. For example, for a first repetition frequency f of about 1GHz₁A round-trip length of about 30cm in the optical cavity was chosen. In this case, the physical length L of the optical cavity is about 15cm, and the radius of curvature of the mirrors M3 and M4 is about 8 cm. The physical length L of the optical resonator is here four times lower than a two-mirror optical resonator with the same round trip length. In another example, for a first repetition frequency f at 3GHz₁An oscillator operating selectively in the optical cavityA round trip length of about 10cm, with the radius of curvature of the mirrors M3, M4 being about 2.5 cm. The mirrors M1, M2, M3, M4 have a diameter of between 1mm and a few centimeters, for example about 6mm (or 1/4 inches). However, this configuration presents technical difficulties in optical alignment of the optical cavity, limiting the efficiency with which the optical cavity can be maintained. This configuration requires miniaturized and very high precision opto-mechanical adjustments to achieve the required interferometric adjustments. A very compact optical resonator is thus obtained. The optical cavity is folded, which allows to reduce the volume of the optical cavity around the interaction region. An optical resonator is very convenient. This compactness allows the optical resonator to be placed in a small volume vacuum chamber, thereby significantly simplifying the implementation of the system. The compactness of the vacuum chamber and the optical resonator allows for better isolation of ambient vibrations and reduces the cost of the overall system. Furthermore, even if the optical cavity is placed in a vacuum chamber, its volume is small, so the system can be inserted more easily into the charged particle beam line, the environment of which is often disturbed by various scientific instruments. This configuration allows for easier interaction between very high intensity laser pulses and the charged particle beam in a defined interaction region.

Fig. 3 shows the mounting of the supports of mirrors M1, M2, M3 and M4 on the same platform 28. More precisely, mirror M1 is mounted on support 21, and mirror M2 is mounted on support 22, mirror M3 is mounted on support 23, and mirror M4 is mounted on support 24. The support 21 is arranged on the translation plate 41. Similarly, the supports 22, 23, 24 are arranged on respective translation plates 42, 43, 44, respectively.

Fig. 4 shows the mounting of the mirror M1 on the support 21 with the micrometer adjuster 31 in more detail.

More precisely, the frequency of the laser oscillator 1 operating in pulsed mode on the optical resonator 10 is controlled so as to store the energy of the burst of laser pulses by constructive interference.

In a variant using a regenerative amplifier to generate the burst of pulses, the length of the optical regenerative cavity determining the first repetition frequency is controlled on the optical resonant cavity 10 in order to store the energy of the burst of laser pulses by constructive interference.

The mirror M1 is configured so that a portion 200 of the low power pulse beam injected simultaneously with the pulse train enters the optical cavity 10. The detector 12 detects a portion 200 of the low power pulsed beam extracted from the optical cavity. The portion 200 of the low power pulse beam is also at the first repetition frequency f₁。

The servo control system 13 deduces therefrom an error signal and applies the error signal to control the cavity of the laser oscillator 1 or the optical regeneration cavity of the regeneration amplifier. Thus, the first repetition frequency f is controlled according to the length of the optical cavity₁To maximize the energy and/or power of the giant pulse in the interaction region 25 of the optical cavity. The control loop operates at a frequency of about 1 MHz. Thus, the frequency of the laser source is controlled according to the slow drift of the length of the optical cavity 10.

FIG. 5 illustrates an opto-mechanical mounting of a four-mirror optical resonator. It is particularly advantageous for the optical cavity 10 to comprise a first opening 26 in the frame 23 below the spherical mirror M3. Likewise, the optical cavity 10 includes a second opening 27 in the frame 24 above the mirror M4.

The optical resonant cavity may be implemented on a particle accelerator.

In the application of the interaction between the electron beam and the laser beam, an electron beam 40 is injected into the optical cavity 10, as shown in fig. 6 and 7. More precisely, the electron beam 40 is directed towards the focal region of the optical cavity 10 through the first opening 26 and/or the second opening 27. Thus, the electron beam 40 may interact with the giant pulse formed in the interaction region 25 of the optical cavity 10. This interaction produces an inverse compton scattered beam 50 that can be detected.

The diameter of the spherical mirrors M3, M4 determines the minimum crossing angle between the charged particle beam 40 and the laser beam 160.

By means of the translation plates 41, 42, 43 and/or 44, the distance between the mirrors can be adjusted according to the distance between the packets of charged particles. The overlap of the giant laser pulse and the charged particle beam is better if the crossing angle ALPHA is low and the lateral dimension of the laser beam is small relative to the lateral dimension of the charged particle beam. For a cavity with a round trip length of about 30cm, a crossing angle ALPHA of less than or equal to 3 deg. or 4 deg. is obtained.

This system is particularly advantageous in the case where packets of charged particles are emitted with an inter-packet period of about 1ns, i.e. a frequency in the order of gigahertz. In practice, the first repetition frequency f of the oscillator₁May be synchronized via a second servo control system on the generation frequency of the packets of charged particles.

Fig. 8 shows an optical resonant cavity according to a three mirror variant. In this variant, the optical resonator 10 comprises a flat mirror M1 for injection and two spherical mirrors M3, M4. The three mirrors M1, M3, M4 are arranged in a planar configuration. Advantageously, the two spherical mirrors M3, M4 are arranged in a concentric configuration. For example, the spherical mirrors M3, M4 have the same radius of curvature R/2, and the distance between the mirrors M3 and M4 is equal to R. Thus, the interaction region on which the giant laser pulse is focused is located at half the distance between mirror M3 and mirror M4. Here, the physical length L of the three-mirror optical cavity is three times lower than that of the two-mirror optical cavity having the same round trip length.

Fig. 9 shows a variant of an ultra-short and high-energy giant laser pulse generating system, which further comprises further detectors 14, 15, 16 arranged to detect further leakage signals from the mirrors M2 and M4.

In another application, a laser source controlled on an optical resonator can be used to generate the interaction between the laser beam and the sample and to measure inelastic scattering, for example of the raman scattering type.

For this purpose, the sample to be analyzed is placed in the interaction region 25 of the optical resonator of the system as described above, and the beam formed by scattering the giant laser pulse on the sample is collected. The filter separates the scattered beam into a beam representing an elastic or rayleigh scattered component and a beam representing a component of inelastic scattering such as raman scattering. The spectrometer performs a spectral analysis on the inelastic scattered beam. This system allows increasing the intensity of the inelastic scattered beam due to the extremely high intensity of the giant laser pulses incident on the sample.