JP2008052266A - Diffraction method of high-intensity pulse laser beam, transient diffraction grating element, method of suppressing pre-pulse of high-intensity pulse laser beam, method of compressing chirped pulse laser beam, method of generating phase conjugate beam, and method of generating spectrum phase conjugate beam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems that, in most of solid-state nonlinear optical elements having light damage thresholds of 1 GW/cm<SP>2</SP>, the structure as an optical element is broken and its optical function is damaged in such a solid-state optical element, because the energy density reaches in a range of 10 TW/cm<SP>2</SP>to 100 PW/cm<SP>2</SP>when a high-intensity laser beam of TW-class or PW-class having an ultra high peak output of 0.1 TW to 1 PW is condensed to irradiate the solid-state optical element therewith. <P>SOLUTION: The transient diffraction grating element comprises a periodic spatial density distribution of plasma generated by light flux interference wherein the high-intensity pulse laser beam with a plurality of ultra high peak outputs of 0.1 TW to 1 PW are projected so as to cross in a gas, liquid, or solid transparent medium. Utilizing the transient diffraction grating element: (1) the high-intensity pulse laser beam is diffracted; (2) a pre-pulse is removed from the high-intensity pulse laser beam; (3) the high-intensity pulse laser beam is compressed; (4) a phase conjugate beam of the high-intensity pulse laser beam is obtained; and (5) a spectrum phase conjugate beam of a chirped pulse laser beam is obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

High-intensity pulsed laser light with peak power exceeding TW can be applied to high-order harmonic generation, laser acceleration, laser fusion, etc. by generating plasma using its extreme light intensity. The present invention provides a high-intensity pulsed laser beam diffraction method, a transient diffraction grating element, particularly a high-intensity pulsed laser beam pre-pulse suppression method, a high-intensity pulsed laser beam compression method, a phase conjugate light generation method, The present invention relates to a method for generating spectral phase conjugate light.

Even when trying to diffract high-intensity pulsed laser light with ordinary solid-state optical elements, the optical damage threshold of most nonlinear optical elements is about 1 GW / cm ² , and high-intensity laser light with an ultra-high peak output of 0.1 TW to 1 PW is used. When condensed and irradiated, the energy density becomes 10TW / cm ^{2 to} 100PW / cm ² , so the usual solid optical element is damaged, the structure as an optical element is broken, and the optical function is impaired. is there.

In high-intensity pulsed laser light used for high-order harmonic generation, laser acceleration, laser fusion, X-ray generation, etc., high-intensity pulsed laser-induced plasma generates high-energy particles such as electrons, ions, and X-rays This is one effective technique. The particles generated thereby have a time width from picoseconds to subpicoseconds. This high energy particle generation process strongly depends on the laser prepulse preceding the high intensity laser pulse. Even if the pre-pulse is about 10 ^{-8 of the} main pulse in high-intensity pulsed laser light, when the 10TW class laser light is focused on the target, the light intensity of the main pulse is easily 0.1 PW / cm ² to 10 ² PW / cm ² is reached, the light intensity of the prepulse is on the order of TW / cm ^2, and parasitic plasma is generated only by the prepulse. In this case, the parasitic plasma generated by the pre-pulse serves as a shield, and the main pulse does not reach the target efficiently, and desired plasma is not generated.

Therefore, in high-intensity pulsed laser-induced plasma, the most important is not just light intensity but time control including suppression of unnecessary prepulses such as ASE (Amplified Spontaneous Emission). There are several prepulse suppression methods, such as Pockels cell and amplification seed pulse shaping. Recently, prepulse control using the interaction between a plasma generated on a thin film and a high-intensity femtosecond laser is known. (Non-Patent Document 1). Also, for the purpose of suppressing this pre-pulse, the energy density becomes 10TW / cm ^{2 to} 100PW / cm ² when condensing and irradiating high intensity laser light with ultra high peak output 0.1TW ~ 1PW on glass or silicon substrate, A dense plasma is generated. A plasma mirror using the skin effect has been proposed (Non-Patent Document 2). However, the plasma mirror cannot perform dispersion compensation or light wave branching.

On the other hand, conventionally, when light wave mixing is performed using an ultrashort pulse laser in a low-intensity pulsed laser beam, an output light pulse that appears through a transient diffraction grating is obtained as a third-order intensity correlation waveform of the incident light pulse. A coherent gate method is known in which an incoherent prepulse component associated with an incident light pulse is removed and a background-free output light pulse can be generated (Non-patent Document 3). However, ultra-high peak power 0.1TW~1PW in high-intensity pulsed laser light (light collection, the energy density is 10TW / cm ² ~100PW / cm ² when irradiated) is not realized.

Furthermore, in recent years, it has been found that a diffraction grating can be written in the vicinity of the glass surface by two-beam interference of femtosecond laser pulses in the near infrared region (Non-patent Document 4, Patent Document 1). An amplified titanium sapphire laser pulse with a central wavelength of 800 nm and a pulse width of 130 fs is used as a light source, and the laser pulse is divided into two beams of equal intensity by a beam splitter, and focused at the same angle inside the sample by a lens with a focal length of 150 nm. . Laser pulses that overlap in time and space are condensed on the surface of the silica glass to form interference fringes. On the glass surface, a periodic structure corresponding to the intensity distribution of interference fringes can be produced. However, the inventions described in Non-Patent Document 4 and Patent Document 1 merely form a periodic structure in glass, and the diffraction grating formed by the methods of these documents has an ultrahigh peak output of 0.1 TW to 1 PW. When the high-intensity pulsed laser beam is condensed, the energy density becomes 10TW / cm ^{2 to} 100PW / cm ² , so ablation occurs and damages the structure as an optical element, and the optical function is impaired. .

The technique of pulse compression of laser light is to compress a laser pulse having a linear frequency change (frequency increases linearly with time) into a medium having anomalous dispersion (an anomalous dispersion medium). In the anomalous dispersion medium, the propagation speed of the low frequency portion located in the front portion of the pulse is slow, and the optical pulse is compressed. There is a method using a pair of diffraction gratings arranged in parallel as an anomalous dispersion medium. This method has been proposed by E. Treacy (Non-Patent Document 5). However, ultra-high peak power 0.1TW～1PW (energy density ^{10TW / cm 2 ~100PW / cm 2} ) condensing the high-intensity pulsed laser light in the diffraction grating of the solid is irradiated, the energy density of 10TW / cm ² ~100PW Since / cm ² , ablation occurs and damage occurs.

Phase conjugate light refers to light that travels in the opposite direction with spatially the same wavefront with respect to certain light. An element that generates phase conjugate light is called a phase conjugater. Even if the phase disturbance object receives a spatial wavefront distortion while the light is propagating, if the light is returned on the same optical path as phase conjugate light, the returned light will reverse the spatial distortion in the opposite direction. Therefore, the distortion is canceled and the original wavefront is restored. It is known that phase conjugate light is generated by various nonlinear phenomena. One of these is the photorefractive effect. When a photorefractive medium such as a photorefractive crystal is irradiated with light, a spatial electric field is generated in the medium, and the refractive index of the substance is generated via the Pockels effect. Is a phenomenon that changes. In order to generate phase conjugate light, there are roughly divided methods called degenerate four-wave mixing, self-excitation type, and mutual excitation type. However, when high-intensity pulsed laser light with an ultra-high peak output of 0.1TW to 1PW is focused and irradiated onto a solid photorefractive crystal, etc., the energy density becomes 10TW / cm ^{2 to} 100PW / cm ² , resulting in ablation and damage Resulting in.

Prepulse control of high-intensity femtosecond laser by propagation in thin film plasma, Proceedings of the 1st Annual Meeting of Particle Accelerator Society of Japan and the 29th Linear Accelerator Meeting in Japan (August 4-6, 2004, Funabashi Japan) Ch. Ziener, J. Appl. Phys. 93, 768 (2003) S. C. W. Hyde, et.al., Opt. Lett. 20 (1995) 1131-1133 K. Kawamura, T. Ogawa, N. Sarukura, M. Hirano, H. Hosono: Fabrication of surface relief gratings on transparent dielectric materials by two-beam holography method using infrared femtosecond laser pulses; Appl. Phys. B (Rapid Communication) , 71, 119, (2000). Optical pulse compression with diffraction gratings, (IEEE, J.QE, vol.QE-5, page 454-458, 1969) JP 2003-57422 A

Therefore, the present invention has been made to solve the above problems,
(1) Diffraction method of high-intensity pulsed laser light with ultra-high peak output 0.1TW to 1PW (2) Method of removing pre-pulse from high-intensity pulsed laser light with ultra-high peak output 0.1TW to 1PW (of high-intensity pulsed laser light Prepulse suppression method)
(3) Ultra high peak output 0.1TW～1PW (condenser, energy density when irradiated is 10TW / cm ² ~100PW / becomes cm ²⁾ also incident repeated high intensity pulsed laser beam ablation problems (4) Method of compressing chirped pulsed laser light (5) Method of obtaining phase conjugate light of high-intensity pulsed laser light with ultra-high peak output of 0.1TW to 1PW, and (6) Chirped pulsed laser light An object of the present invention is to provide a method for obtaining a spectral phase conjugate light of

The present invention
[1] Using the periodic spatial density distribution of plasma generated by light beam interference by irradiating two high-intensity pump pulsed laser beams so as to cross in gas or liquid as a transient diffraction grating, A method for diffracting high-intensity pulsed laser light, wherein self-diffracted light of intensity-pumped pulsed laser light is expressed.
[2] The high-intensity pump pulsed laser light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the self-diffracted light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds. In addition, the method for diffracting high-intensity pulsed laser light according to [1], which has an ultrahigh peak output of 0.1 TW to 1 PW.
[3] Using the periodic spatial density distribution of plasma generated by light beam interference by irradiating two high-intensity pump pulsed laser beams so as to cross in a gas or a liquid, as a transient diffraction grating, A diffraction method for high-intensity pulsed laser light, wherein high-intensity probe pulsed laser light is incident on a transient diffraction grating and diffracted light of the high-intensity probe pulsed laser light is expressed.
[4] The high-intensity pump pulsed laser light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the high-intensity probe pulsed laser light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds and ultra high peak output 0.1TW to 1PW, and the diffracted light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds and ultra high peak output 0.1TW to 1PW [3] Of high-intensity pulsed laser light.
[5] The diffraction method of high-intensity pulsed laser light according to any one of [1] to [4], wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol.
[5-1] The prepulse suppression method for high-intensity pulsed laser light according to [5], wherein the rare gas or nitrogen gas is injected in a vacuum chamber.
[5-2] [5] or [5-1], wherein the rare gas is neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas Prepulse suppression method for high-intensity pulsed laser light.
[5-3] The prepulse suppression method for high-intensity pulsed laser light according to [5], wherein the liquid is a flowing liquid.
[6] Periodic space of plasma generated in the vicinity of the crossing position by irradiating two high-intensity pump pulsed laser beams so as to cross in the solid transparent medium, causing light beam interference to ablate the solid transparent medium A method of diffracting high-intensity pulsed laser light, wherein self-diffracted light of high-intensity pump pulsed laser light is expressed using the density distribution as a transient diffraction grating.
[7] The high-intensity pump pulsed laser light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the self-diffracted light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds. In addition, the method for diffracting high-intensity pulsed laser light according to [6], which has an ultrahigh peak output of 0.1 TW to 1 PW.
[8] Periodic space of plasma generated in the vicinity of the crossing position by irradiating two high-intensity pump pulsed laser beams so as to cross in the solid transparent medium, causing light beam interference to ablate the solid transparent medium A method of diffracting high-intensity pulsed laser light, wherein the density distribution is used as a transient diffraction grating, and high-intensity probe pulsed laser light is incident on the transient diffraction grating to express diffracted light from the high-intensity probe pulsed laser light. .
[9] The high-intensity pump pulsed laser light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the high-intensity probe pulsed laser light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds and ultrahigh peak output 0.1TW to 1PW, and the diffracted light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and ultrahigh peak output 0.1TW to 1PW [8] Of high-intensity pulsed laser light.
[10] The high-intensity pulsed laser light diffraction method according to any one of [6] to [9], wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic.
[11] A transient diffraction grating comprising a periodic spatial density distribution of plasma generated by light beam interference by irradiating two high-intensity pump pulsed laser beams so as to cross in gas or liquid element.
[12] The transient diffraction grating element according to [11], wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol.
[12-1] The prepulse suppression method of high-intensity pulsed laser light according to [12], wherein the rare gas or nitrogen gas is injected in a vacuum chamber.
[12-2] [12] or [12-1], wherein the rare gas is neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas Prepulse suppression method for high-intensity pulsed laser light.
[12-3] The prepulse suppression method for high-intensity pulsed laser light according to [12], wherein the liquid is a flowing liquid.
[13] Periodic space of plasma generated near the crossing position by ablating the solid transparent medium due to light beam interference caused by irradiation with two high-intensity pump pulsed laser beams so as to cross in the solid transparent medium A transient diffraction grating element comprising a density distribution.
[14] The transient diffraction grating element according to [13], wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic.
[15] The two high-intensity pump pulsed laser beams have an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW [11], [12], [12 -1], [12-2], [12-3], [13], [14] The transient diffraction grating element according to any one of [14].
[16] Periodic spatial density distribution of plasma generated by light beam interference by irradiating high-intensity pump pulsed laser light and high-intensity probe pulsed laser light with a prepulse so as to cross in gas or liquid A prepulse suppression method for high-intensity pulsed laser light, characterized in that light wave mixing is performed using a diffractive grating as a transient diffraction grating, and prepulse-free high-intensity pulsed laser light is expressed as diffracted light.
[16-1] The direction in which the diffracted light appears is phase matching when the wave number vectors of the high-intensity pump pulse laser light, the high-intensity probe pulse laser light, and the diffracted light are k ₂ , k ₁ , and k _d , respectively. conditions _{k d ~k 2 + (k 2} -k 1) , characterized in that it is adjusted to meet the 16] prepulse inhibition method of the high-intensity pulsed laser light according. In the formula, “˜” means “nearly equal”.
[17] The prepulse suppression method for high-intensity pulsed laser light according to [16] or [16-1], wherein the gas is a rare gas or nitrogen gas, and the liquid is water or ethanol.
[17-1] The prepulse suppression method of high-intensity pulsed laser light according to [17], wherein the rare gas or nitrogen gas is injected in a vacuum chamber.
[17-2] [17] or [17-1], wherein the rare gas is neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas Prepulse suppression method for high-intensity pulsed laser light.
[17-3] The prepulse suppression method for high-intensity pulsed laser light according to [17], wherein the liquid is a flowing liquid.
[18] Irradiation of high-intensity pump pulsed laser light and high-intensity probe pulsed laser light accompanied by a pre-pulse so as to cross in the solid transparent medium causes light beam interference, and the solid transparent medium is ablated and the crossing position Pre-pulse suppression of high-intensity pulsed laser light, characterized in that pre-pulse-free high-intensity pulsed laser light is expressed as diffracted light by using the periodic spatial density distribution of plasma generated nearby as a transient diffraction grating Method.
[18-1] The direction in which the diffracted light appears is phase matching when the wave number vectors of the high-intensity pump pulse laser light, the high-intensity probe pulse laser light, and the diffracted light are k ₂ , k ₁ , and k _d , respectively. conditions _{k d ~k 2 + (k 2} -k 1) , characterized in that it is adjusted to meet the 18] prepulse inhibition method of the high-intensity pulsed laser light according. In the formula, “˜” means “nearly equal”.
[19] The prepulse suppression method for high-intensity pulsed laser light according to [18], wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic.
[20] The high-intensity pump pulse laser beam has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the high-intensity probe pulse laser beam has an ultrashort pulse width of 1 femtosecond to 100 picoseconds and ultrahigh peak output 0.1TW to 1PW, and the diffracted light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and ultrahigh peak output 0.1TW to 1PW [16], [16-1], [17], [17-1], [17-2], [17-3], [18], [18-1], [19] High intensity pulse in any one of [19] Laser pulse prepulse suppression method.
[21] Transient composed of periodic spatial density distribution of plasma generated by light beam interference by irradiating high intensity pump pulse laser light and high intensity probe pulse laser light so as to cross in gas or liquid A pair of diffraction gratings are formed so as to face each other, a chirped pulse laser beam is incident on the first transient diffraction grating of the pair of transient diffraction gratings, and a high-intensity pulse laser that is diffracted light from the transient diffraction grating A method of compressing a chirped pulse laser beam, comprising: making light incident on a second transient diffraction grating and diffracting a high-intensity pulsed laser beam pulse-compressed from the second transient diffraction grating.
[21-1] direction in which the diffracted light appears, the high-intensity pump pulsed laser beam, the high intensity probe pulse laser light and the wave vector of the diffracted light, respectively k _2, when the k _1, k _d, the phase The chirped pulse laser compression method according to [21], wherein the chirped pulse laser light compression method is adjusted so as to satisfy the matching conditions k _{d to} k ₂ + (k ₂ −k ₁ ).
[22] The chirped pulse laser compression method according to [21] or [21-1], wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol.
[22-1] The chirped pulse laser beam compression method according to [22], wherein the rare gas or nitrogen gas is injected in a vacuum chamber.
[22-2] [22] or [22-1], wherein the rare gas is neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas Compression method of chirp pulse laser light.
[22-3] The chirped pulse laser compression method according to [22], wherein the liquid is a flowing liquid.
[23] Irradiation of high-intensity pump pulsed laser light and high-intensity probe pulsed laser light so as to cross in the solid transparent medium causes light beam interference, and the solid transparent medium is ablated and generated near the crossing position. A transient diffraction grating having a periodic spatial density distribution of the plasma is formed so as to be opposed to each other, and a chirped pulse laser beam is incident on the first transient diffraction grating of the transient diffraction grating pair, The high-intensity pulsed laser light, which is diffracted light from the grating, is incident on the second transient diffraction grating, and the high-intensity pulsed laser light pulse-compressed from the second transient diffraction grating is diffracted. A method of compressing chirped pulse laser light.
[23-1] direction in which the diffracted light appears, the high-intensity pump pulsed laser beam, the high intensity probe pulse laser light and the wave vector of the diffracted light, respectively k _2, when the k _1, k _d, the phase The chirped pulse laser compression method according to [23], wherein the chirped pulse laser light compression method is adjusted so as to satisfy matching conditions k _{d to} k ₂ + (k ₂ −k ₁ ).
[24] The chirped pulse laser compression method according to [23] or [23-1], wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic.
[25] The high-intensity pump pulse laser beam has an ultrashort pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the high-intensity probe pulse laser beam has an ultrashort pulse width of 1 femtosecond to 100 picoseconds and ultrahigh peak output 0.1TW to 1PW, and the diffracted light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and ultrahigh peak output 0.1TW to 1PW [21], [21-1], [22], [22-1], [22-2], [22-3], [23], [23-1], [24] Light compression method.
[26] Four-wave mixing is performed by irradiating a high-intensity forward pump pulse laser beam, a high-intensity backward pump pulse laser beam, and a high-intensity probe pulse laser beam so as to cross in a gas or a liquid. A method for generating phase conjugate light, wherein phase conjugate light for the high-intensity probe pulse laser beam is generated using a periodic spatial density distribution of plasma generated by light wave interference of two laser beams as a transient diffraction grating.
[26-1] the direction in which the phase conjugate light appears, the high intensity probe pulse laser beam, high intensity forward pump pulsed laser beam, high intensity backward pump pulsed laser beam and k ₁ the wave vector of the phase conjugate light, _{respectively,} k _fp, k _bp, when the _{k d,} the phase matching condition _{k d = k fp + k bp} -k 1 be adjusted to meet the characterized [26] a method of generating a phase conjugate light according to any one .
[27] The method for generating phase conjugate light according to [26] or [26-1], wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol.
[27-1] The method for generating phase conjugate light according to [27], wherein the rare gas or nitrogen gas is injected in a vacuum chamber.
[27-2] [27] or [27-1], wherein the rare gas is neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas Of generating phase conjugate light.
[27-3] The method for generating phase conjugate light according to [27], wherein the liquid is a flowing liquid.
[28] Four-wave mixing is performed by irradiating a high-intensity forward pump pulse laser beam, a high-intensity backward pump pulse laser beam, and a high-intensity probe pulse laser beam so as to cross in a solid transparent medium. Phase conjugate light is generated for the high-intensity probe pulsed laser beam by using a periodic spatial density distribution of plasma generated near the crossing position by ablation of the solid transparent medium by light wave interference of laser light as a transient diffraction grating. A method of generating phase conjugate light.
[29] The method for generating phase conjugate light according to [28], wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic.
[30] The high-intensity forward pump pulse laser beam and the high-intensity backward pump pulse laser beam have an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW. The light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW [26], [26-1], [27], [27-1], The method for generating phase conjugate light according to any one of [27-2], [27-3], [28], and [29].
[31] Transient diffraction consisting of a periodic spatial density distribution of plasma generated by light beam interference by irradiating a positive chirped pulsed laser beam and a Fourier-limited pulsed laser beam oppositely in a gas or liquid A method of generating spectral phase conjugate light, comprising forming a grating and generating negative chirped pulse laser light from the transient diffraction grating.
[31-1] The direction in which the negative chirped pulse laser beam appears is the phase matching condition when the wave number vectors of the Fourier limit pulse, the positive chirp pulse, and the negative chirp pulse are k _FT , k _PCP , and k _NCP , respectively. The method for generating spectral phase conjugate light according to [31], wherein k _NCP = k _FT + (− k _FT −k _PCP ) is adjusted.
[32] The method for generating spectral phase conjugate light according to [31] or [31-1], wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol.
[32-1] The method for generating spectral phase conjugate light according to [32], wherein the rare gas or nitrogen gas is injected in a vacuum chamber.
[32-2] [32] or [32-1], wherein the rare gas is neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas Method for generating spectral phase conjugate light.
[32-3] The method of generating spectral phase conjugate light according to [32], wherein the liquid is a flowing liquid.
[33] A positive chirped pulse laser beam and a Fourier-limited pulsed laser beam are irradiated in the solid transparent medium so as to oppose each other, so that light beam interference occurs and the solid transparent medium is ablated and generated near the crossing position. A method of generating spectral phase conjugate light, wherein a transient diffraction grating composed of a periodic spatial density distribution of plasma is formed, and negative chirped pulse laser light is generated from the transient diffraction grating.
[33-1] The direction in which the negative chirped pulse laser beam appears is the phase matching condition when the wave number vectors of the Fourier limit pulse, the positive chirp pulse, and the negative chirp pulse are k _FT , k _PCP , and k _NCP , respectively. The method for generating spectral phase conjugate light according to [33], wherein the method is adjusted so as to satisfy k _NCP = k _FT + (− k _FT −k _PCP ).
[34] The method for generating spectral phase conjugate light according to [33] or [33-1], wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic.
About.

Most solid nonlinear optical elements have an optical damage threshold of about 1 GW / cm ² , and the energy density is high when high-intensity laser beams of TW class and PW class with ultra-high peak output of 0.1 TW to 1 PW are condensed and irradiated. also becomes a ^{10TW / cm 2 ~100PW / cm 2} , broken structure as an optical element in the solid optical element, optical function is impaired. On the other hand, according to the present invention, a new (virgin new) transient diffraction grating can be generated when necessary, so that it can cope with high-intensity laser beams of TW class and PW class, specifically,
(1) It can diffract high-intensity pulsed laser light with an ultra-high peak output of 0.1 TW to 1 PW.
(2) Prepulses can be removed from high-intensity pulsed laser light with an ultrahigh peak output of 0.1 TW to 1 PW.
(3) transient grating element, ultra high peak power 0.1TW~1PW repeated high-intensity pulsed laser light (light collection, the energy density is 10TW / cm ² ~100PW / cm ² when irradiated) incident Even so, it can be in a new (virgin new) state when needed and there is no ablation problem.
(4) The chirped pulse laser beam can be compressed.
(5) It is possible to obtain phase conjugate light of high-intensity pulsed laser light having an ultrahigh peak output of 0.1 TW to 1 PW.
(6) Spectral phase conjugate light of chirped pulse laser light can be obtained.

The diffraction method of the high-intensity pulsed laser light according to the first aspect of the present invention is the periodicity of plasma generated by light beam interference caused by irradiating two high-intensity pump pulsed laser lights so as to cross in gas or liquid. Using the spatial density distribution as a transient diffraction grating, self-diffracted light of high-intensity pump pulsed laser light is expressed.
Further, in the first invention, the high-intensity pulsed laser beam diffraction method using a solid transparent medium instead of in gas or liquid crosses two high-intensity pump pulsed laser beams in the solid transparent medium. Irradiation causes light beam interference to ablate the solid transparent medium, and the self-diffracted light of high-intensity pump pulsed laser light is generated using the periodic spatial density distribution of plasma generated near the crossing position as a transient diffraction grating It is characterized by making it.

A method for diffracting high-intensity pulsed laser light according to the first invention will be described with reference to FIG.
When two high-intensity pump pulsed laser beams 2 and 3 are crossed in the gas or liquid 1, periodic interference fringes are formed in the intersecting region of the two laser beams. In the bright and dark places where the interference fringes are alternately adjacent, gas or liquid is photoexcited to generate plasma, and a periodic spatial density distribution of the plasma is generated. Generated. When the transient diffraction grating is generated, the forward arrangement degenerate four-wave mixing occurs, so that the self-diffracted light 5 appears. Here, if the angle between both rays before entering the gas or liquid is θ _0, and the wave vectors of each ray are k _a and k _b , respectively, the interference fringe pattern formed in the intersecting region of these two rays The vector q of the plasma transient diffraction grating and the pitch (interval) d of the transient diffraction grating 4 are given by the following equations, respectively.
_{q = ± (k a -k b} )
d = λ _p / 2sin (θ / 2)
λ _p : wavelength in gas or liquid with refractive index n (λ ₀ / n)
θ: sin θ ₀ = n · sin θ If the crossing angle θ ₀ is sufficiently small before being incident on a gas or liquid that satisfies the condition:
d≈λ ₀ / θ ₀
The pitch (interval) d of the transient diffraction grating can be changed by changing θ ₀ .

The contrast of the plasma transient diffraction grating is determined by the product of the intensities of the two interfering laser beams, and a high-contrast plasma transient diffraction grating is produced when the two laser beams reach the gas or liquid simultaneously. In addition, when the plasma transient diffraction grating and the high-intensity pump pulse laser light satisfy the Bragg condition, self-diffracted light appears in a predetermined direction.
[Bragg condition]
nλ = 2dsinθ
n: positive integer λ: wavelength d: grating interval θ: viewing angle (90 ° -incident angle)

In the method of diffracting high intensity pulse laser light of the first invention, high intensity pump pulse laser light 2 (wave vector k ₂ ), high intensity pump pulse laser light 3 (wave vector k ₁ ), and self-diffracted light 5 (wave vector) The phase matching condition of k _d ) is as follows, and the direction in which self-diffracted light appears is adjusted to satisfy this phase matching condition. In the formula, “˜” means “nearly equal”.

Further, when the high-intensity probe pulse laser light is irradiated so as to satisfy the Bragg condition on the transient diffraction gratings generated by the two high-intensity pump pulse laser lights, the high-intensity probe pulse laser light is diffracted by the transient diffraction grating.

In the diffraction method of the high-intensity pulse laser beam of the first invention, the pulse width of the high-intensity pump pulse laser beam is preferably 1 femtosecond to 100 picoseconds, for example, 100 femtosecond, high-intensity probe pulse laser beam. Is preferably 1 femtosecond to 100 picoseconds, for example, 100 femtoseconds. In the method of diffracting high-intensity pulse laser light of the first invention, the pulse width of the self-diffracted light of the high-intensity pump pulse laser light and the diffracted light of the high-intensity probe pulse laser light is 1 femtosecond to 100 picoseconds. Some are preferred, for example 100 femtoseconds.

The wavelength λ ₀ of the high-intensity pump pulse laser beam and the high-intensity probe pulse laser beam is not particularly limited, but is preferably in the 800 nm band or 1 μm band, for example, 800 nm. Each wavelength of the two high-intensity pump pulse laser beams to be crossed must be the same.

In the diffraction method of the high-intensity pulse laser light of the first invention, the high-intensity pump pulse laser light, the high-intensity probe pulse laser light, the self-diffracted light of the high-intensity pump pulse laser light, and the diffracted light of the high-intensity probe pulse laser light The ultra-high peak output is preferably 0.1 TW to 1 PW. When these high-intensity pump pulse laser light and high-intensity probe pulse laser light are condensed and irradiated, the energy density becomes 10 TW / cm ^{2 to} 100 PW / cm ² . The condensing means is preferably a dielectric multilayer mirror. The diffraction efficiency strongly depends on the light intensity, and when it exceeds 1 PW / cm ² , a high diffraction efficiency exceeding several 10% can be obtained. In an ideal case, the pulse width of the diffracted light is 1 / √3 of the incident light.

In the method for diffracting high-intensity pulsed laser light according to the first aspect of the present invention, the light intensity ratio of the two high-intensity pump pulsed laser beams to be crossed is 1: 1000 to 1: 1 in terms of contrast of the transient diffraction grating. preferable.

In the diffraction method of the high-intensity pulse laser beam of the first invention, the two high-intensity pump pulse laser beams are single pulses, but if the repetition period is longer than the plasma recombination time (if the repetition frequency is about kHz) It may be a repetitive pulse. In the case of a repetitive pulse, it is preferable that the gas and liquid flow.

In the high intensity pulse laser light diffraction method of the first invention, the light source of the high intensity pump pulse laser light and the high intensity probe pulse laser light is preferably a femtosecond laser titanium sapphire laser, Yb doped laser, or Nd doped laser. .

In the method for diffracting high-intensity pulsed laser light according to the first aspect of the present invention, the time difference between two intersecting high-intensity pump pulsed laser beams is 1 femtosecond to 100 picoseconds, and the diffraction efficiency is highest when there is no time difference.

In the high intensity pulsed laser beam diffraction method of the first invention, the gas is preferably a rare gas or a nitrogen gas, and the liquid is preferably water or ethanol.
Examples of the rare gas include helium (He) gas, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas. Among these rare gases, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas are preferable, and similarly, nitrogen (N) gas is also preferable. The rare gas or the nitrogen gas is desirably ejected in a vacuum, and specifically, it is desirably ejected by a gas jet into the vacuum chamber. Note that the density of plasma which is a transient diffraction grating can be controlled by the concentration of a rare gas or nitrogen gas.

Regarding the diffraction method of the high-intensity pulsed laser beam according to the first invention, a diffraction method of the high-intensity pulsed laser beam using a solid transparent medium instead of in gas or liquid will be described.
This high-intensity pulsed laser beam diffraction method causes light beam interference by irradiating two high-intensity pump pulsed laser beams so as to cross each other in the solid transparent medium, and the solid transparent medium at the bright part of the interference fringes. The high-intensity pump pulsed laser beam is self-diffracted using a periodic spatial density distribution of plasma generated near the crossing position as a transient diffraction grating. Note that, along with the ablation, a relief type diffraction grating is also formed in the solid transparent medium.
The position where the two high-intensity pump pulsed laser beams intersect in the solid transparent medium is the surface layer portion or the inside of the solid transparent medium. In particular, the surface layer portion of a solid transparent medium is preferable from the viewpoint of ablation.

The solid transparent medium may be a transparent solid, and is preferably ice, glass, quartz, BK7, sapphire, or transparent plastic.

Further, when the high-intensity probe pulse laser light is irradiated so as to satisfy the Bragg condition on the transient diffraction gratings generated by the two high-intensity pump pulse laser lights, the high-intensity probe pulse laser light is diffracted by the transient diffraction grating.

The time during which the order of the plasma density, which is a transient diffraction grating, is maintained is on the order of nanoseconds, and is sufficiently longer than the time required for pulse control of a high-intensity laser (about the laser pulse width). When the two high-intensity pump pulse laser beams to be crossed are repetitive pulses, the order of plasma density, which is a transient diffraction grating, is constantly maintained. In that case, it is necessary to change the irradiation position of the solid transparent medium for each one pulse, and it is preferable to move the solid transparent medium on the electric stage for each one pulse.

The transient diffraction grating element according to the second aspect of the present invention is based on the periodic spatial density distribution of plasma generated by light beam interference by irradiating two high-intensity pump pulsed laser beams so as to cross in gas or liquid. It is characterized by.
Moreover, the transient diffraction grating element using a solid transparent medium instead of in gas or liquid in the second aspect of the present invention irradiates two high-intensity pump pulse laser beams so as to cross each other in the solid transparent medium. It is characterized by comprising a periodic spatial density distribution of plasma generated near the crossing position by ablation of the solid transparent medium due to light beam interference.

The transient diffraction grating element of the second invention will be described with reference to FIG.
The transient diffraction grating element according to the second aspect of the invention crosses a high-intensity pump pulse laser beam 2 and a high-intensity pump pulse laser beam 3 in a gas or liquid 1 and periodically interferes with the intersecting region of the two lights. It is produced by forming. In the bright and dark places where the interference fringes are alternately adjacent, the gas or liquid is photoexcited to generate high-density plasma, and in the dark place low-density plasma or no plasma is generated. A periodic spatial density distribution of the plasma is generated, and the periodic spatial density distribution of the plasma itself is the transient diffraction grating element 4.
Here, if the angle between both rays before entering the gas or liquid is θ _0, and the wave vectors of each ray are k _a and k _b , respectively, the interference fringe pattern formed in the intersecting region of these two rays The vector q of the plasma transient diffraction grating and the pitch (interval) d of the transient diffraction grating 4 are given by the following equations, respectively.
_{q = ± (k a -k b} )
d = λ _p / 2sin (θ / 2)
λ _p : wavelength in gas or liquid with refractive index n (λ ₀ / n)
θ: sin θ ₀ = n · sin θ If the crossing angle θ ₀ is sufficiently small before being incident on a gas or liquid that satisfies the condition:
d≈λ ₀ / θ ₀
The pitch (interval) d of the transient diffraction grating can be changed by changing θ ₀ .

In the second invention, the phase matching of the high-intensity pump pulse laser beam 2 (wave vector k ₂ ), the high-intensity pump pulse laser beam 3 (wave vector k ₁ ) and the self-diffracted beam 5 (wave vector k _d ) in FIG. The conditions are as follows, and the direction in which the self-diffracted light appears is adjusted to satisfy this phase matching condition. In the formula, “˜” means “nearly equal”.

In the second invention, the pulse width of the high-intensity pump pulse laser light is preferably 1 femtosecond to 100 picoseconds, for example, 100 femtoseconds.

In the second invention, the wavelength λ ₀ of the high-intensity pump pulse laser light is not particularly limited, but is preferably in the 800 nm band or 1 μm band, for example, 800 nm. Each wavelength of the two high intensity pump pulsed laser beams must be the same.

In the second invention, the ultra-high peak output of the high-intensity pump pulse laser light is preferably 0.1 TW to 1 PW. When the high-intensity pump pulse laser beam is condensed and irradiated, the energy density becomes 10 TW / cm ^{2 to} 100 PW / cm ² . The condensing means is preferably a dielectric multilayer mirror. The diffraction efficiency strongly depends on the light intensity, and when it exceeds 1 PW / cm ² , a high diffraction efficiency exceeding several 10% can be obtained. In an ideal case, the pulse width of the diffracted light is 1 / √3 of the incident light.

In the second invention, the light intensity ratio of the two high-intensity pump pulse laser beams to be crossed is preferably 1: 1000 to 1: 1 in terms of contrast of the transient diffraction grating.

In the second invention, the high-intensity pump pulse laser beam is a single pulse, but may be a repetitive pulse as long as the repetition period is longer than the plasma recombination time (if the repetition frequency is about kHz).

In the second invention, the light source of the high-intensity pump pulse laser light is preferably a titanium sapphire laser, a Yb-doped laser, or an Nd-doped laser that is a femtosecond laser.

In the second invention, the time difference between the two high-intensity pump pulse laser beams to be crossed is 1 femtosecond to 100 picoseconds, and the diffraction efficiency is highest when there is no time difference.

In the transient diffraction grating element of the second invention, the gas is preferably a rare gas or a nitrogen gas, and the liquid is more preferably water or ethanol. Examples of the rare gas include helium (He) gas, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas. Among these rare gases, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas are preferable, and similarly, nitrogen (N) gas is also preferable. The rare gas or the nitrogen gas is desirably ejected in a vacuum, and specifically, it is desirably ejected by a gas jet into the vacuum chamber. Note that the density of plasma which is a transient diffraction grating can be controlled by the concentration of a rare gas or nitrogen gas.

Regarding the transient diffraction grating element of the second invention, a transient diffraction grating element that uses a solid transparent medium instead of in gas or liquid will be described.
This transient diffraction grating element causes light beam interference by irradiating two high-intensity pump pulse laser beams so as to cross each other in the solid transparent medium, and ablate the solid transparent medium in the bright part of the interference fringe. Using the periodic spatial density distribution of plasma generated in the vicinity of the crossing position as a transient diffraction grating, high-intensity pump pulsed laser light is self-diffracted. Note that, along with the ablation, a relief type diffraction grating is also formed in the solid transparent medium.

The solid transparent medium may be a transparent solid, and is preferably ice, glass, quartz, BK7, sapphire, or transparent plastic.

The time during which the order of the plasma density, which is a transient diffraction grating, is maintained is on the order of nanoseconds, and is sufficiently longer than the time required for pulse control of a high-intensity laser (about the laser pulse width). When the high-intensity pump pulse laser beam is a repetitive pulse, the order of plasma density, which is a transient diffraction grating, is constantly maintained.

The prepulse suppressing method of the high intensity pulsed laser beam according to the third aspect of the invention is a method of irradiating a high intensity pump pulsed laser beam and a high intensity probe pulsed laser beam accompanied with a prepulse so as to cross in a gas or a liquid. Light wave mixing is performed using a periodic spatial density distribution of plasma generated by interference as a transient diffraction grating, and prepulse-free high-intensity pulsed laser light is expressed as diffracted light.
Further, the prepulse suppression method for high-intensity pulsed laser light using a solid transparent medium instead of gas or liquid in the third aspect of the present invention is obtained by combining high-intensity pump pulsed laser light and high-intensity probe pulsed laser light with prepulses into solid Light wave mixing is performed by using the periodic spatial density distribution of plasma generated near the crossing position as a result of light beam interference caused by irradiation to cross in the transparent medium and ablating the solid transparent medium as a transient diffraction grating, Pre-pulse-free high-intensity pulsed laser light is expressed as diffracted light.

The prepulse suppression method for high-intensity pulsed laser light according to the third invention and the transient diffraction grating element according to the second invention will be described with reference to FIG.
When the high-intensity pump pulsed laser beam 12 and the high-intensity probe pulsed laser beam 13 with a prepulse are crossed in the gas or liquid 11, periodic interference fringes are formed in the intersecting region of the two laser beams. In the bright and dark places where the interference fringes are alternately adjacent to each other, the gas or liquid 11 is photoexcited to generate plasma, and a periodic spatial density distribution of the plasma is generated. Is generated. When the transient diffraction grating 14 is generated, forward arrangement degenerate four-wave mixing occurs, so that self-diffracted light 15 appears. Here, assuming that the angle formed by both light rays before entering the gas or liquid 11 is θ ₀ and the wave vectors of the respective light rays are k _a and k _b , respectively, an interference fringe pattern formed in the intersection region of the two light rays. The vector q of the plasma transient diffraction grating and the pitch (interval) d of the transient diffraction grating 14 are given by the following equations, respectively.
_{q = ± (k a -k b} )
d = λ _p / 2sin (θ / 2)
λ _p : wavelength in gas or liquid with refractive index n (λ ₀ / n)
θ: sin θ ₀ = n · sin θ before the incidence to the rare gas that satisfies the condition θ ₀
d≈λ ₀ / θ ₀
It is approximated as can vary the pitch (spacing) d of the transient grating 14 by varying the theta _0.

The contrast of the plasma transient diffraction grating 14 is determined by the product of the intensities of two interfering laser beams. Further, the plasma transient diffraction grating 14 is generated only when two laser beams reach the target gas at the same time. Therefore, for example, when the main pulse 13a of the high-intensity probe pulse laser 13 light with the prepulse 13b and the main pulse 12a of the high-intensity pump pulse laser light 12 with the prepulse 12b are crossed in synchronization, the prepulse alone is at the crossing point. Then, the high-contrast plasma transient diffraction grating 14 is not generated, and the prepulse passes as it is. The high-contrast plasma transient diffraction grating 14 is generated by the main pulse light 13a of the high-intensity probe pulsed laser light 13 and the main pulse light 12a of the high-intensity pump pulsed laser light 12 that reach the intersection next, and plasma transient diffraction is generated. When the grating 14 and the high-intensity probe pulsed light 13 satisfy the Bragg condition, self-diffracted light 15 (15a is the main pulse and 15b represents the position where the prepulse 12b was present) in which the prepulse is suppressed appears. Since the diffraction efficiency of the self-diffracted light 15 is given by the product of the square of the incident main pulse light intensity and the pump pulse intensity, the high-intensity probe pulse laser light without a pre-pulse (high contrast) is self-directed in a predetermined direction. Appears as diffracted light 15.
[Bragg condition]
nλ = 2dsinθ
n: positive integer λ: wavelength d: grating interval θ: viewing angle (90 ° -incident angle)

In the prepulse suppression method of the high intensity pulse laser beam of the third invention, the high intensity pump pulse laser beam 12 (wave number vector k ₂ ), the high intensity probe pulse laser beam 13 (wave number vector k ₁ ), and the self-diffracted beam 15 (wave number). The phase matching condition of the vector k _d ) is as follows, and the direction in which self-diffracted light appears is adjusted to satisfy this phase matching condition. In the formula, “˜” means “nearly equal”.

In the prepulse suppression method of the high intensity pulse laser beam of the third invention, the pulse width of the high intensity pump pulse laser beam is preferably 1 femtosecond to 100 picosecond, for example, 100 femtosecond, high intensity probe pulse laser. The pulse width of light is preferably 1 femtosecond to 100 picoseconds, for example, 100 femtoseconds. In the prepulse suppression method for high intensity pulsed laser light according to the third invention, the pulse width of diffracted light that is prepulse-free high intensity pulsed laser light is preferably 1 femtosecond to 100 picoseconds, for example 100 Femtosecond.

The wavelength λ ₀ of the high-intensity pump pulse laser beam and the high-intensity probe pulse laser beam is not particularly limited, but is preferably in the 800 nm band or 1 μm band, for example, 800 nm. Each wavelength of the high intensity pump pulse laser light and the high intensity probe pulse laser light must be the same.

In the prepulse suppression method of the high intensity pulse laser light of the third invention, the ultrahigh peak output of the diffracted light which is the high intensity pump pulse laser light, the high intensity probe pulse laser light and the prepulse free high intensity pulse laser light is 0.1 TW-1PW is preferred. When these high-intensity pump pulse laser light and high-intensity probe pulse laser light are condensed and irradiated, the energy density becomes 10 TW / cm ^{2 to} 100 PW / cm ² . The condensing means is preferably a dielectric multilayer mirror. The diffraction efficiency strongly depends on the light intensity, and when it exceeds 1 PW / cm ² , a high diffraction efficiency exceeding several 10% can be obtained. In an ideal case, the pulse width of the diffracted light is 1 / √3 of the incident light.

In the prepulse suppression method of the high intensity pulse laser light of the third invention, the light intensity ratio between the high intensity pump pulse laser light and the high intensity probe pulse laser light is 1: 1000 to 1: 1 in terms of the contrast of the transient diffraction grating. It is preferable that

In the prepulse suppression method of the high intensity pulse laser light of the third invention, the high intensity pump pulse laser light and the high intensity probe pulse laser light are single pulses, but if the repetition period is longer than the plasma recombination time (repetition frequency). If it is about kHz, it may be a repetitive pulse. In the case of a repetitive pulse, it is preferable that the gas and liquid flow.

In the high-intensity pulsed laser light prepulse suppression method of the third invention, the light source of the high-intensity pulsed laser light is preferably a femtosecond laser such as a titanium sapphire laser, a Yb-doped laser, or an Nd-doped laser.

In the prepulse suppression method of the high-intensity pulsed laser beam according to the third invention, the time difference between the high-intensity pump pulsed laser beam and the high-intensity probe pulsed laser beam is 1 femtosecond to 100 picoseconds. High efficiency.

In the prepulse suppression method for high-intensity pulsed laser light according to the third invention, the gas is preferably a rare gas or a nitrogen gas, and the liquid is more preferably water or ethanol. Examples of the rare gas include helium (He) gas, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas. Among these rare gases, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas are preferable, and similarly, nitrogen (N) gas is also preferable. The rare gas or the nitrogen gas is desirably ejected in a vacuum, and specifically, it is desirably ejected by a gas jet into the vacuum chamber. Note that the density of plasma which is a transient diffraction grating can be controlled by the concentration of a rare gas or nitrogen gas. The liquid is preferably a flowing liquid.

The prepulse suppressing method for high intensity pulsed laser light according to the third aspect of the invention will be described with reference to a method for suppressing high intensity pulsed laser light using a solid transparent medium instead of gas or liquid.
This pre-pulse suppression method for high-intensity pulsed laser light is produced by irradiating high-intensity pump pulsed laser light and high-intensity probe pulsed laser light with prepulses so as to cross in a solid transparent medium. It is characterized by light wave mixing using the periodic spatial density distribution of plasma generated near the crossing position after ablation of a transparent medium as a transient diffraction grating, and pre-pulse-free high-intensity pulsed laser light is expressed as diffracted light. It is characterized by doing. Note that, along with the ablation, a relief type diffraction grating is also formed in the solid transparent medium.

The solid transparent medium may be a transparent solid, and is preferably ice, glass, quartz, BK7, sapphire, or transparent plastic.

In addition, the time during which the order of the plasma density, which is a transient diffraction grating, is maintained is on the order of nanoseconds, and is sufficiently longer than the time required for pulse control of a high intensity laser (about the laser pulse width). When the high-intensity pump pulse laser beam and the high-intensity probe pulse laser beam are repetitive pulses, the order of the plasma density, which is a transient diffraction grating, is constantly maintained.

The chirped pulse laser light compression method according to the fourth aspect of the present invention is generated by light beam interference by irradiating high intensity pump pulse laser light and high intensity probe pulse laser light so as to cross in gas or liquid. A transient diffraction grating having a periodic spatial density distribution of the plasma is formed so as to be opposed to each other, and a chirped pulse laser beam is incident on the first transient diffraction grating of the transient diffraction grating pair, The high-intensity pulsed laser light, which is diffracted light from the grating, is incident on the second transient diffraction grating, and the high-intensity pulsed laser light pulse-compressed from the second transient diffraction grating is diffracted. To do.
The chirped pulse laser light compression method using a solid transparent medium instead of gas or liquid in the fourth aspect of the invention crosses high intensity pump pulse laser light and high intensity probe pulse laser light in a solid transparent medium. In such a manner, a pair of transient diffraction gratings composed of a periodic spatial density distribution of plasma generated near the crossing position by ablating the solid transparent medium due to light beam interference caused by irradiation is formed so as to face each other. The chirped pulse laser beam is incident on the first transient diffraction grating of the transient diffraction grating pair, and the high-intensity pulsed laser beam, which is the diffracted light from the transient diffraction grating, is incident on the second transient diffraction grating. It comprises diffracting high-intensity pulsed laser light that has been pulse-compressed from two transient diffraction gratings.

A method for compressing chirped pulse laser light according to the fourth aspect of the present invention will be described with reference to FIG.
Raising the frequency of light in time (up chirp) or descending (down chirp) is called chirping. In pulse compression, an anomalous dispersion type (frequency) is used for up-chirped pulses (up-chirp pulses). A compression circuit having a higher delay time is shorter), and a normally distributed compression circuit is required for a down-chirped pulse (down-chirp pulse).

The chirp pulse laser light compression method according to the fourth aspect of the invention is generated by light beam interference by irradiating the high intensity pump pulse laser light 32a and the high intensity probe pulse laser light 33a so as to cross in the gas or liquid 31a. Similarly, the high-intensity pump pulse laser beam 32b and the high-intensity probe pulse laser beam 33b are irradiated so as to cross in the gas or liquid 31a. Thus, a pair of transient diffraction gratings (34 (a combination of 34a and 34b)) in which the second transient diffraction grating 34b composed of the periodic spatial density distribution of the plasma generated by the light beam interference is arranged to face each other is provided. The first transient diffraction grating has a broader wavelength range, and the pulse extends in time. A high-intensity pulsed laser beam 37 that is incident on the second transient diffraction grating 34b and incident on the second transient diffraction grating 34b. Is diffracted. In this pulse compression, when the up-chirped pulse laser beam 35 is incident on the plasma transient diffraction grating pair 34, the transient diffraction grating pair 34 causes an angular dispersion (down chirp) to be a negative group velocity dispersion ( The propagation speed of the low-frequency part located in the front part of the pulse is reduced).

In the chirped pulse laser light compression method of the fourth invention, the high-intensity pump pulse laser light 32a (wave number vector k ₂ ), the high-intensity probe pulse laser light 33a (wave number vector k ₁ ), and the diffracted light 34a (wave number vector k _d). ) Is as follows, and the direction in which self-diffracted light appears is adjusted to satisfy this phase matching condition. The phase matching conditions for the high-intensity pump pulse laser beam 32b (wave vector k ₂ ), the high-intensity probe pulse laser beam 33b (wave vector k ₁ ), and the diffracted beam 34b (wave vector k _d ) are the same. In the formula, “˜” means “nearly equal”.

In the chirp pulse laser light compression method of the fourth invention, the pulse width of the high-intensity pump pulse laser light is preferably 1 femtosecond to 100 picoseconds, for example, 100 femtoseconds, The pulse width is preferably 1 femtosecond to 100 picoseconds, for example, 100 femtoseconds. In the chirped pulse laser compression method of the fourth aspect of the present invention, the pulse width of the diffracted light is preferably 1 femtosecond to 100 picoseconds, for example, 100 femtoseconds.

In the chirp pulse laser light compression method of the fourth invention, the wavelength λ ₀ of the high-intensity pump pulse laser light and the high-intensity probe pulse laser light is not particularly limited, but is preferably in the 800 nm band or 1 μm band. 800 nm. Each wavelength of the high intensity pump pulse laser light and the high intensity probe pulse laser light must be the same.

In the chirped pulse laser light compression method of the fourth aspect of the present invention, high-intensity pump pulsed laser light, high-intensity probe pulsed laser light, and ultrahigh peak powers of diffracted light of 0.1 TW to 1 PW are preferable. When these high-intensity pump pulse laser light and high-intensity probe pulse laser light are condensed and irradiated, the energy density becomes 10 TW / cm ^{2 to} 100 PW / cm ² . The condensing means is preferably a dielectric multilayer mirror. The diffraction efficiency strongly depends on the light intensity, and when it exceeds 1 PW / cm ² , a high diffraction efficiency exceeding several 10% can be obtained. In an ideal case, the pulse width of the diffracted light is 1 / √3 of the incident light.

In the chirp pulse laser light compression method of the fourth invention, the light intensity ratio between the high-intensity pump pulse laser light and the high-intensity probe pulse laser light is 1: 1000 to 1: 1 in terms of the contrast of the grating. preferable.

In the chirp pulse laser light compression method of the fourth invention, the high-intensity pump pulse laser light and the high-intensity probe pulse laser light are single pulses, but if the repetition period is longer than the plasma recombination time (repetition frequency is kHz). It can be a repetitive pulse. In the case of a repetitive pulse, it is preferable that the gas and liquid flow.

In the chirped pulse laser light compression method of the fourth invention, the light source of the high-intensity pulsed laser light is preferably a femtosecond laser titanium sapphire laser, Yb-doped laser, or Nd-doped laser.

In the chirp pulse laser light compression method of the fourth aspect of the invention, the time difference between the high-intensity pump pulse laser light and the high-intensity probe pulse laser light is preferably several femtoseconds or less, and is best when there is no time difference.

In the chirped pulse laser compression method of the fourth invention, the gas is preferably a rare gas or a nitrogen gas, and the liquid is more preferably water or ethanol. Examples of the rare gas include helium (He) gas, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas. Among these rare gases, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas are preferable, and similarly, nitrogen (N) gas is also preferable. The rare gas or the nitrogen gas is desirably ejected in a vacuum, and specifically, it is desirably ejected by a gas jet into the vacuum chamber. Note that the density of plasma which is a transient diffraction grating can be controlled by the concentration of a rare gas or nitrogen gas. The liquid is preferably a flowing liquid.

Regarding the compression method of the chirped pulse laser light according to the fourth aspect of the present invention, a method for compressing the chirped pulse laser light using a solid transparent medium instead of gas or liquid will be described.
This pre-pulse suppression method for high-intensity pulsed laser light involves irradiation of high-intensity pump pulsed laser light and high-intensity probe pulsed laser light so that they intersect in the solid transparent medium, causing light beam interference and A pair of transient diffraction gratings composed of a periodic spatial density distribution of plasma generated near the crossing position after ablation are arranged opposite to each other, and a chirp pulse is applied to the first transient diffraction grating of the transient diffraction grating pair A laser beam is incident, a high-intensity pulsed laser beam that is diffracted from the transient diffraction grating is incident on the second transient diffraction grating, and a high-intensity pulsed laser beam pulse-compressed from the second transient diffraction grating is generated. It is characterized by comprising diffracting. Note that, along with the ablation, a relief type diffraction grating is also formed in the solid transparent medium.

The solid transparent medium may be a transparent solid, and is preferably ice, glass, quartz, BK7, sapphire, or transparent plastic.

In the chirped pulse laser light compression method of the fourth aspect of the invention, the chirped pulsed laser light has a broader band so that the phases of all frequency components are aligned, and the pulse is extended in time. Is from subpicoseconds to 1000 picoseconds.

In the chirped pulse laser light compression method of the fourth aspect of the invention, the distance between the first transient diffraction grating and the second transient diffraction grating is not particularly limited, but is 1 cm to 100 cm. The second transient diffraction grating is disposed on the optical path of the diffracted laser light from the first transient diffraction grating.

In the chirped pulse laser beam compression method of the fourth aspect of the invention, the chirped pulsed laser beam has a diffraction condition “sinγ + sin (γ−θ) = λ / d _g = 2πc / ωd _{g on} the first transient diffraction grating surface, γ: angle of incidence of chirped pulse laser beam on first transient diffraction grating, θ: angle of diffraction from first diffraction grating, λ: center wavelength of chirped pulse laser beam, d _g : groove interval of transient diffraction grating It is desirable to enter so as to satisfy “some”.

The pulse width of the chirp laser light, which was sub-picosecond to 1000 picoseconds before compression, becomes a level of several femtoseconds after compression.

In the method for generating phase conjugate light according to the fifth aspect of the invention, high intensity forward pump pulse laser light, high intensity backward pump pulse laser light, and high intensity probe pulse laser light are irradiated so as to cross in gas or liquid. The four-wave mixing is performed to generate phase conjugate light for the high-intensity probe pulsed laser beam using the periodic spatial density distribution of the plasma generated by the light wave interference of the three laser beams as a transient diffraction grating. To do.
Further, the method of generating phase conjugate light using a solid transparent medium in place of gas or liquid in the fifth invention includes a high intensity forward pump pulse laser light, a high intensity backward pump pulse laser light, and a high intensity probe pulse laser light. Are mixed so as to cross in a solid transparent medium, and four-wave mixing is performed, and the periodic spatial density of plasma generated in the vicinity of the crossing position is ablated by the solid transparent medium due to light wave interference of the three laser beams. The distribution is used as a transient diffraction grating to generate phase conjugate light for the high-intensity probe pulse laser beam.

A method for generating phase conjugate light according to the fifth aspect of the invention will be described with reference to FIG. The method for generating phase conjugate light according to the fourth aspect of the present invention involves crossing high intensity probe pulse laser light 42, high intensity forward pump pulse laser light 43, and high intensity backward pump pulse laser light 44 in gas or liquid 41. Irradiating in such a manner that backward degenerate four-wave mixing is performed, and three types of plasma transient diffraction gratings 45 of transmission type, reflection type, and 2k type are formed by interference of three light waves, and as a result, phase conjugate Light 46 is generated. The high-intensity forward pump pulse laser beam 43 and the high-intensity backward pump pulse laser beam 44 are preferably irradiated so as to face each other. A spatially conjugate wavefront is called a phase conjugate wave.

In the method for generating phase conjugate light according to the fifth aspect of the present invention, high intensity probe pulse laser light 42 (wave number vector k ₁ ), high intensity forward pump pulse laser light 43 (wave number vector k _fp ), high intensity backward pump pulse laser light 44. The phase matching conditions of (wave number vector k _bp ) and phase conjugate light 46 (wave number vector k _d ) are as follows, and the direction in which phase conjugate light appears is adjusted to satisfy this phase matching condition.

In the method for generating phase conjugate light according to the fifth aspect of the present invention, the pulse widths of the high intensity forward pump pulse laser light and the high intensity backward pump pulse laser light are preferably 1 femtosecond to 100 picoseconds, for example, 100 femtoseconds. The pulse width of the high-intensity probe pulse laser light is preferably 1 femtosecond to 100 picoseconds, for example, 100 femtoseconds.

The wavelength λ ₀ of the high-intensity forward pump pulse laser light, the high-intensity backward pump pulse laser light, and the high-intensity probe pulse laser light is not particularly limited, but is preferably in the 800 nm band or 1 μm band, for example, 800 nm.

In the method for generating phase conjugate light according to the fifth aspect of the invention, the ultrahigh peak outputs of the high intensity forward pump pulse laser light, the high intensity backward pump pulse laser light, and the high intensity probe pulse laser light are preferably 0.1 TW to 1 PW. When these high-intensity forward pump pulse laser light, high-intensity backward pump pulse laser light, and high-intensity probe pulse laser light are condensed and irradiated, the energy density becomes 10 TW / cm ^{2 to} 100 PW / cm ² . The condensing means is preferably a dielectric multilayer mirror. The diffraction efficiency strongly depends on the light intensity, and when it exceeds 1 PW / cm ² , a high diffraction efficiency exceeding several 10% can be obtained. In an ideal case, the pulse width of the diffracted light is 1 / √3 of the incident light.

In the method for generating phase conjugate light according to the fifth aspect of the invention, the light intensity ratio of the high intensity forward pump pulse laser light and the high intensity backward pump pulse laser light is 1: 1000 to 1: 1 in terms of contrast of the transient diffraction grating. It is preferable that the ratio is 1: 100 to 1: 1. The light intensity ratio between the high-intensity forward pump pulse laser beam and the high-intensity probe pulse laser beam is preferably 1: 1000 to 1: 1 in terms of contrast of the transient diffraction grating, more preferably 1: 100 to 1: 1. Further, the light intensity ratio between the high intensity backward pump pulsed laser beam and the high intensity probe pulsed laser beam is preferably 1: 1000 to 1: 1 in terms of contrast of the transient diffraction grating, more preferably 1: 100. ~ 1: 1.

In the method for generating phase conjugate light according to the fifth aspect of the present invention, the high intensity forward pump pulse laser light, the high intensity backward pump pulse laser light, and the high intensity probe pulse laser light are single pulses, but have a repetition period from the plasma recombination time. May be a repetitive pulse (if the repetitive frequency is about kHz). In the case of a repetitive pulse, it is preferable that the gas and liquid flow.

In the method for generating phase conjugate light according to the fifth aspect of the invention, the light source of the high-intensity pulsed laser light is preferably a femtosecond laser, a titanium sapphire laser, a Yb-doped laser, or an Nd-doped laser.

In the method for generating phase conjugate light according to the fifth aspect of the present invention, the time difference between the high intensity forward pump pulse laser light and the high intensity backward pump pulse laser light is about the pulse width, and when there is no time difference, the diffraction efficiency is most desirable. Further, the time difference between the high intensity forward pump pulse laser beam and the high intensity probe pulse laser beam is about the pulse width, and the diffraction efficiency is highest when there is no time difference. The time difference between the high intensity backward pump pulse laser beam and the high intensity probe pulse laser beam needs to be shorter than the plasma recombination time, and the diffraction efficiency is highest when there is no time difference.

In the method for generating phase conjugate light according to the fifth aspect of the invention, the gas is preferably a rare gas or a nitrogen gas, and the liquid is more preferably water or ethanol. Examples of the rare gas include helium (He) gas, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas. Among these rare gases, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas are preferable, and similarly, nitrogen (N) gas is also preferable. The rare gas or the nitrogen gas is desirably ejected in a vacuum, and specifically, it is desirably ejected by a gas jet into the vacuum chamber. Note that the density of plasma which is a transient diffraction grating can be controlled by the concentration of a rare gas or nitrogen gas. The liquid is preferably a flowing liquid.

Regarding the method for generating phase conjugate light according to the fifth invention, a method for generating phase conjugate light using a solid transparent medium instead of gas or liquid will be described.
This phase conjugate light is generated by four-wave mixing by irradiating high intensity forward pump pulse laser light, high intensity backward pump pulse laser light and high intensity probe pulse laser light so as to cross in a solid transparent medium. Phase conjugate light with respect to the high-intensity probe pulse laser beam using a periodic spatial density distribution of plasma generated near the crossing position by ablation of the solid transparent medium due to light wave interference of the three laser beams as a transient diffraction grating Is generated. Note that, along with the ablation, a relief type diffraction grating is also formed in the solid transparent medium.

The solid transparent medium may be a transparent solid, and is preferably ice, glass, quartz, BK7, sapphire, or transparent plastic.

The time for maintaining the order of the plasma density is on the order of nanoseconds, which is sufficiently longer than the time required for pulse control of the high intensity laser (about the laser pulse width).

The method for generating spectral phase conjugate light according to the sixth aspect of the present invention is generated by causing light beam interference by irradiating positive chirped pulse laser light and Fourier limit pulse laser light in gas or liquid so as to face each other. A transient diffraction grating composed of a periodic spatial density distribution of plasma is formed, and negative chirp pulse laser light is generated from the transient diffraction grating.
In addition, in the sixth aspect of the invention, the method for generating spectral phase conjugate light using a solid transparent medium instead of gas or liquid makes positive chirp pulse laser light and Fourier limit pulse laser light face each other in the solid transparent medium. In this way, a light beam interference occurs and the solid transparent medium is ablated to form a transient diffraction grating composed of a periodic spatial density distribution of plasma generated near the crossing position, and a negative chirp pulse is generated from the transient diffraction grating. It is characterized by generating laser light.

A method for generating spectral phase conjugate light according to the sixth aspect of the invention will be described with reference to FIG.
In the method for generating spectral phase conjugate light according to the present invention, a positive chirped pulsed laser beam 52 (an optical pulse whose frequency is increasing with time) and a Fourier-limited pulsed beam 53 are opposed to each other in a gas or liquid 51. When a periodic interference fringe is formed, the medium is photoexcited in the bright and dark places where the interference fringes alternately intersect, generating plasma, and in a spatially positive direction A chirped plasma diffraction grating 54 (refractive index grating), which is a transient diffraction grating having a wider diffraction grating width, is generated. That is, the lattice spacing of the formed plasma diffraction grating 54 is spatially chirped. This is called a chirp plasma diffraction grating 54. If this chirped plasma transient diffraction grating 54 is read using a Fourier-limited pulse 53 in a time shorter than the plasma recombination time, a pulsed laser beam (spectrum) having a chirp opposite in time to the chirped pulse laser beam used for writing. As phase diffracted light 55, that is, diffracted light by the chirped plasma diffraction grating 54, spectral phase conjugate light 55 (negative chirped pulse light (the frequency of the light decreases with time) in the moving direction of the Fourier-limited pulsed light 53. Light pulse)) is generated. The spectral phase conjugate light means a conjugate light wave in the spectral region.

In the method for generating spectral phase conjugate light according to the sixth aspect of the present invention, Fourier-limited pulse 53 (wave vector k _FT ), positive chirp pulse laser beam 52 (wave vector k _PCP ), and negative chirp pulse laser beam 55 (wave vector k The phase matching condition of _NCP ) is as follows, and the direction in which the negative chirped pulse laser beam, that is, the spectral phase conjugate light appears, is adjusted to satisfy this phase matching condition.

In the method for generating spectral phase conjugate light according to the sixth aspect of the present invention, the Fourier limit pulse is preferably generated by the method for compressing high-intensity pulsed laser light according to the third aspect, and the pulse width is 1 femtosecond to It is 100 picoseconds, for example, 100 femtoseconds, and the ultrahigh peak output is 0.1 TW to 1 PW (energy density 10 TW / cm ^{2 to} 100 PW / cm ² ). When the Fourier limit pulse is condensed and irradiated, the energy density becomes 10 TW / cm ^{2 to} 100 PW / cm ² .

In the method for generating spectral phase conjugate light according to the sixth aspect of the present invention, the positive chirped pulse laser beam is broadened so that the phases of all frequency components are aligned, and the pulse is extended in time. The pulse width is from subpicoseconds to 1000 picoseconds, for example, 10 picoseconds, and the ultrahigh peak output is from 0.1 TW to 1 PW. When the Fourier limit pulse is condensed and irradiated, the energy density becomes 10 TW / cm ^{2 to} 100 PW / cm ² . The condensing means is preferably a dielectric multilayer mirror. The diffraction efficiency strongly depends on the light intensity, and when it exceeds 1 PW / cm ² , a high diffraction efficiency exceeding several 10% can be obtained. In an ideal case, the pulse width of the diffracted light is 1 / √3 of the incident light.

In the method for generating spectral phase conjugate light according to the sixth aspect of the invention, the Fourier-limited pulse and the chirped pulse laser light are single pulses, but are repeated if the repetition period is longer than the plasma recombination time (if the repetition frequency is about kHz). A pulse may be used. In the case of a repetitive pulse, it is preferable that the gas and liquid flow.

In the method for generating spectral phase conjugate light according to the sixth invention, the gas is preferably a rare gas or a nitrogen gas, and the liquid is more preferably water or ethanol. Examples of the rare gas include helium (He) gas, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas. Among these rare gases, neon (Ne) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas are preferable, and similarly, nitrogen (N) gas is also preferable. The rare gas or the nitrogen gas is desirably ejected in a vacuum, and specifically, it is desirably ejected by a gas jet into the vacuum chamber. Note that the density of plasma which is a transient diffraction grating can be controlled by the concentration of a rare gas or nitrogen gas. The liquid is preferably a flowing liquid.

Regarding the method for generating spectral phase conjugate light according to the sixth aspect of the invention, a method for generating spectral phase conjugate light using a solid transparent medium instead of gas or liquid will be described.
This spectral phase conjugate light is generated by irradiating positive chirped pulsed laser light and Fourier-limited pulsed laser light in a solid transparent medium so as to oppose each other, causing light beam interference and ablating the solid transparent medium. A transient diffraction grating composed of a periodic spatial density distribution of plasma generated in the vicinity of the crossing position is formed, and negative chirped pulse laser light is generated from the transient diffraction grating. Note that, along with the ablation, a relief type diffraction grating is also formed in the solid transparent medium.

The solid transparent medium may be a transparent solid, and is preferably ice, glass, quartz, BK7, sapphire, or transparent plastic.

High intensity pulse laser light diffraction method, high intensity pulse laser light prepulse suppression method, transient diffraction grating element, chirp pulse laser light compression method, phase conjugate light generation method, and spectral phase conjugate light generation method of the present invention As for the embodiment, the formation of these basic transient diffraction gratings was confirmed by the diffraction method of the high-intensity pulsed laser beam of the present invention. FIG. 6 is a conceptual diagram of a diffraction method of high-intensity pulsed laser light.

As shown in FIG. 6, two high-intensity pump pulse laser beams (61, 62) and a high-intensity probe pulse laser beam 63 are condensed by a lens 64, and two high-intensity pump pulse laser beams (61 ′, 61) are collected. 62 ′), high-intensity probe pulsed laser light 63 ′ was irradiated so as to cross in quartz glass 65 having a thickness of 1 μm (crossing portion 65a). The light source of the high-intensity pump pulse laser beam was an Nd: YAG laser (wavelength: 1064 nm, repetition frequency: 10 Hz, pulse width: 15 ps).
Two high-intensity pump pulsed laser beams in the quartz glass 65 cause light beam interference, and the quartz glass 65 in the bright part of the interference fringes is ablated, and a periodic spatial density distribution of plasma is present near the surface of the quartz glass 65. Generated. FIG. 7 is a conceptual diagram showing a state in which the quartz glass 65 is ablated and a periodic spatial density distribution 66 of plasma is generated in the vicinity of the surface of the quartz glass 65.
The periodic spatial density distribution 66 of this plasma is the transient diffraction grating 66. With the ablation, a relief type diffraction grating 67 was also formed in the quartz glass. FIG. 8 shows a photograph of the relief type diffraction grating 67 formed on the quartz glass. Note that this photograph has a time delay of 0 seconds.

The high-intensity pump pulse laser beam is self-diffracted by the formed transient diffraction grating 66 and the relief-type diffraction grating 67, and the diffracted light 68 in the lower row in FIG. 9 is observed, and the high-intensity probe pulse laser light is diffracted, The diffracted light 69 in the upper row in FIG. 9 was observed. Note that this photograph has a time delay of 0 seconds.

The diffraction efficiency when the high-intensity probe pulsed laser beam 63 (63 ') was incident on the transient diffraction grating 66 with a time delay shown in FIG. 10 was measured (FIG. 10). In FIG. 10, the time delay is 0 second, that is, the diffraction when the high-intensity probe pulse laser beam 63 (63 ′) is irradiated simultaneously with the two high-intensity pump pulse laser beams 61 (61 ′) and 62 (62 ′). Efficiency is 1. FIG. 10 indicates that the diffraction efficiency decreases as the time delay increases. Since the time delay is about 10 ps, the diffraction efficiency is almost the same as the diffraction efficiency when a sufficient time delay is given, and the plasma recombination time is generally about 10 ps. It was confirmed that the periodic spatial density distribution 66 was generated and the transient diffraction grating 66 was formed.

In addition, when the high intensity probe pulsed laser beam 63 (63 ′) is irradiated with a sufficient time delay (reading in the pump-probe method), and when the time delay is 0 second (writing in the pump-probe method). (Writing)), the change in diffraction efficiency due to the energy intensity density of the high-intensity pump pulsed laser beam was confirmed (FIG. 11). In the case of Reading, since the high-intensity probe pulse laser beam is irradiated with a sufficient time delay, diffraction is performed only by the relief type diffraction grating 67 of the quartz glass 65, and the diffraction efficiency is low. On the other hand, in the case of Writing, it can be seen that the energy intensity density of the high-intensity pump pulsed laser beams 61 ′ and 62 ′ is 1 J / cm ² or more and the diffraction efficiency is high. This is because the quartz glass 65 is ablated by the high-intensity pump pulsed laser beams 61 ′ and 62 ′ that are higher than the energy intensity density 1 J / cm ² of the high-intensity pumped pulsed laser beams 61 ′ and 62 ′ as a threshold. This shows that the periodic spatial density distribution 66 of the plasma, that is, the transient diffraction grating 66 is formed.

The diffraction method of the high-intensity pulsed laser beam of the present invention, the transient diffraction grating element, the prepulse suppression method of the high-intensity pulsed laser beam, the compression method of the high-intensity pulsed laser beam, the phase conjugate light generation method and the spectral phase conjugate light generation method are High-order harmonic generation, microfabrication using ultrashort pulse high repetition laser, X-ray (EUV) generation laser technology, coherent X-ray (X-ray laser) excitation technology, fusion laser technology, high energy physics experiment, etc. It can be applied in various fields.

It is a conceptual diagram (including the transient diffraction grating element of this 2nd invention) of the diffraction method of the high intensity | strength pulse laser beam of this 1st invention. It is a conceptual diagram of the prepulse suppression method of the high intensity | strength pulse laser beam of this 3rd invention. It is a conceptual diagram of the compression method of the chirp pulse laser beam of this 4th invention. It is a conceptual diagram of the production | generation method of the phase conjugate light of this 5th invention. It is a conceptual diagram of the production | generation method of the spectrum phase conjugate light of this 6th invention. It is a conceptual diagram of the diffraction method of a high intensity | strength pulse laser beam. It is a conceptual diagram which shows the state which quartz glass ablates and the periodic spatial density distribution of the plasma has arisen. It is a photograph of quartz glass. It is a photograph of the relief type diffraction grating formed in quartz glass. The diffraction efficiency when the time delay of the high-intensity probe pulse laser beam is changed is shown. The change of the diffraction efficiency by the energy intensity density of a high intensity | strength pump pulse laser beam is shown.

Explanation of symbols

1 Gas or liquid 2 High intensity pump pulse laser light 3 High intensity pump pulse laser light 4 Periodic spatial density distribution of plasma or transient diffraction grating 5 Diffracted light of high intensity pump pulse laser light 11 Gas or liquid 12 High intensity pump pulse laser Light 12a Main pulse 12b of high intensity pump pulse laser light Prepulse 13 of high intensity pump pulse laser light High intensity probe pulse laser light 13a Main pulse 13b of high intensity probe pulse laser light Prepulse 14 of high intensity probe pulse laser light Transient diffraction grating Element 15 Self-diffracted light (high-intensity pulsed laser light with suppressed prepulse)
15a Main pulses 31a, 31b of self-diffracted light Gas or liquid 32a, 32b High-intensity pump pulse laser light 33a, 33b High-intensity probe pulse laser light 34a First transient diffraction grating element 34b Second transient diffraction grating element 35 Chirp pulse Laser light 36 First diffracted light 37 Second diffracted light (pulse-compressed high-intensity pulsed laser light)
41 Gas or liquid 42 High-intensity probe pulse laser beam 43 High-intensity forward pump pulse laser beam 44 High-intensity backward pump pulse laser beam 45 Transient diffraction grating element 51 Gas or liquid 52 Positive chirped pulse laser beam 53 Fourier limit pulse 54 Transient diffraction Lattice element 55 Spectral phase conjugate light 61 High-intensity pump pulsed laser light 61 ′ High-intensity pump pulsed laser light 61a condensed by the lens High-intensity pump pulsed laser light diffracted light 61 ”High-intensity pump pulsed laser light 62 High-intensity pump High intensity pump pulse laser light 62a focused by pulse laser light 62 'lens Diffracted light 62 "of high intensity pump pulse laser light High intensity pump pulse laser light 63 High intensity probe pulse laser light 63' Condensed by lens High Degrees probe pulse laser beam 63a high intensity diffracted light 63 of the probe pulse laser beam "high intensity probe pulse laser beam 64 lens 65 quartz glass 65a intersection 66 plasma periodic spatial density distribution or transient grating 67 relief type diffraction grating

Claims (34)

A high-intensity pump pulse using the periodic spatial density distribution of plasma generated as a result of light beam interference by irradiating two high-intensity pump pulse laser beams so as to cross in gas or liquid as a transient diffraction grating A method for diffracting high-intensity pulsed laser light, wherein self-diffracted light of laser light is expressed. The high-intensity pump pulsed laser light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the self-diffracted light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh pulse width. 2. The method of diffracting high-intensity pulsed laser light according to claim 1, wherein the peak output is 0.1 TW to 1 PW. Using the periodic spatial density distribution of plasma generated as a result of light beam interference by irradiating two high-intensity pump pulsed laser beams so as to cross in gas or liquid, the transient diffraction grating A method of diffracting high-intensity pulsed laser light, wherein high-intensity probe pulsed laser light is incident on the surface to cause diffracted light of the high-intensity probe pulsed laser light to appear. The high-intensity pump pulsed laser light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the high-intensity probe pulsed laser light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds. 4. The high intensity according to claim 3, wherein the ultra high peak output is 0.1 TW to 1 PW, and the diffracted light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultra high peak output of 0.1 TW to 1 PW. Pulse laser beam diffraction method. The method for diffracting high-intensity pulsed laser light according to any one of claims 1 to 4, wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol. By irradiating two high-intensity pump pulsed laser beams so as to cross in the solid transparent medium, the solid transparent medium is ablated by causing light beam interference, and the periodic spatial density distribution of the plasma generated near the crossing position is obtained. A method for diffracting high-intensity pulsed laser light, characterized by using self-diffracted light of high-intensity pump pulsed laser light as a transient diffraction grating. The high-intensity pump pulsed laser light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the self-diffracted light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh pulse width. 7. The method of diffracting high-intensity pulsed laser light according to claim 6, wherein the peak output is 0.1 TW to 1 PW. By irradiating two high-intensity pump pulsed laser beams so as to cross in the solid transparent medium, the solid transparent medium is ablated by causing light beam interference, and the periodic spatial density distribution of the plasma generated near the crossing position is obtained. A method for diffracting high-intensity pulsed laser light, characterized by being used as a transient diffraction grating, wherein high-intensity probe pulsed laser light is incident on the transient diffraction grating and diffracted light of the high-intensity probe pulsed laser light is expressed. The high-intensity pump pulsed laser light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the high-intensity probe pulsed laser light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds. 9. The high intensity according to claim 8, wherein the ultra high peak output is 0.1 TW to 1 PW, and the diffracted light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultra high peak output of 0.1 TW to 1 PW. Pulse laser beam diffraction method. The method for diffracting high-intensity pulsed laser light according to any one of claims 6 to 9, wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic. A transient diffraction grating element comprising a periodic spatial density distribution of plasma generated by light beam interference by irradiating two high-intensity pump pulsed laser beams so as to cross in gas or liquid. The transient diffraction grating element according to claim 11, wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol. From the periodic spatial density distribution of the plasma generated near the crossover position by ablating the solid transparent medium by irradiating two high-intensity pump pulsed laser beams so that they cross each other in the solid transparent medium. A transient diffraction grating element characterized by comprising: 14. The transient diffraction grating element according to claim 13, wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic. 15. The two high-intensity pump pulsed laser beams have an ultrashort pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, respectively. Transient diffraction grating element. Transient diffraction of the periodic spatial density distribution of plasma generated by light flux interference by irradiating high-intensity pump pulse laser light and high-intensity probe pulse laser light with prepulses in a gas or liquid. A prepulse suppression method for high-intensity pulsed laser light, characterized in that light pulse mixing is performed as a grating and prepulse-free high-intensity pulsed laser light is expressed as diffracted light. The prepulse suppression method for high-intensity pulsed laser light according to claim 16, wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol. High-intensity pump pulsed laser light and high-intensity probe pulsed laser light with pre-pulse are irradiated so as to cross in the solid transparent medium, and light flux interference occurs, and the solid transparent medium is ablated and generated near the crossing position. A method for suppressing pre-pulse of high-intensity pulsed laser light, characterized in that light wave mixing is performed using the periodic spatial density distribution of the plasma as a transient diffraction grating, and pre-pulse-free high-intensity pulsed laser light is expressed as diffracted light. 19. The prepulse suppression method for high-intensity pulsed laser light according to claim 18, wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic. The high-intensity pump pulsed laser light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the high-intensity probe pulsed laser light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds. The ultra-high peak output is 0.1 TW to 1 PW, and the diffracted light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultra-high peak output of 0.1 TW to 1 PW. The prepulse suppression method for high-intensity pulsed laser light according to any one of the above. A transient diffraction grating consisting of a periodic spatial density distribution of plasma generated by light beam interference by irradiating high-intensity pump pulsed laser light and high-intensity probe pulsed laser light so as to cross in gas or liquid. Forming a pair of oppositely arranged, the chirped pulse laser light is incident on the first transient diffraction grating of the transient diffraction grating pair, and the high-intensity pulsed laser light which is the diffracted light from the transient diffraction grating, A method of compressing chirped pulsed laser light, comprising: diffracting high-intensity pulsed laser light that is incident on a second transient diffraction grating and pulse-compressed from the second transient diffraction grating. The method of claim 21, wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol. High-intensity pump pulsed laser light and high-intensity probe pulsed laser light are irradiated so as to cross in the solid transparent medium, and light flux interference occurs, causing the solid transparent medium to ablate and generate plasma near the crossover position. Forming a pair of transient diffraction gratings having a periodic spatial density distribution so as to be opposed to each other; injecting a chirped pulse laser beam into the first transient diffraction grating of the transient diffraction grating pair; A chirped pulse comprising diffracting high-intensity pulsed laser light, which is diffracted light, incident on a second transient diffraction grating and diffracting pulse-compressed high-intensity pulsed laser light from the second transient diffraction grating Laser light compression method. 24. The method of compressing a chirped pulse laser beam according to claim 23, wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic. The high-intensity pump pulsed laser light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the high-intensity probe pulsed laser light has an ultrashort pulse width of 1 femtosecond to 100 picoseconds. The ultrahigh peak output is 0.1 TW to 1 PW, and the diffracted light has an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW. The chirped pulse laser light compression method according to any one of the above. Four-wave mixing is performed by irradiating a high-intensity forward pump pulse laser beam, a high-intensity backward pump pulse laser beam, and a high-intensity probe pulse laser beam so as to cross in a gas or a liquid. A phase conjugate light generation method for generating phase conjugate light with respect to the high-intensity probe pulsed laser light using a periodic spatial density distribution of plasma generated by the light wave interference of as a transient diffraction grating. 27. The method of generating phase conjugate light according to claim 26, wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol. Four-wave mixing is performed by irradiating a high-intensity forward pump pulse laser beam, a high-intensity backward pump pulse laser beam, and a high-intensity probe pulse laser beam so as to cross in a solid transparent medium. A phase conjugate light is generated with respect to the high-intensity probe pulsed laser beam by using a periodic spatial density distribution of plasma generated near the crossing position by ablation of a transparent solid medium by light wave interference as a transient diffraction grating. A method for generating conjugate light. 29. The method of generating phase conjugate light according to claim 28, wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic. The high-intensity forward pump pulse laser light and the high-intensity backward pump pulse laser light have an extremely short pulse width of 1 femtosecond to 100 picoseconds and an ultrahigh peak output of 0.1 TW to 1 PW, and the high-intensity probe pulse laser light is 30. The method of generating phase conjugate light according to any one of claims 26 to 29, wherein an ultrashort pulse width is 1 femtosecond to 100 picoseconds and an ultrahigh peak output is 0.1 TW to 1 PW. Transient diffraction grating consisting of periodic spatial density distribution of plasma generated by light beam interference by irradiating positive chirped pulsed laser beam and Fourier-limited pulsed laser beam in gas or liquid so as to face each other And generating a negative chirp pulse laser beam from the transient diffraction grating. 32. The method of generating spectral phase conjugate light according to claim 31, wherein the gas is a rare gas or a nitrogen gas, and the liquid is water or ethanol. The period of the plasma generated near the crossing position by ablating the solid transparent medium due to the light beam interference caused by irradiating the positive chirped pulsed laser beam and the Fourier-limited pulsed laser beam in the solid transparent medium so as to face each other A method for generating spectral phase conjugate light, comprising forming a transient diffraction grating having a spatial density distribution and generating a negative chirped pulse laser beam from the transient diffraction grating. 34. The method of generating spectral phase conjugate light according to claim 33, wherein the solid transparent medium is ice, glass, quartz, BK7, sapphire, or transparent plastic.