JP2005070108A - Phase conjugate mirror for ultrashort pulse light, and optical amplifier using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phase conjugate mirror for ultrashort pulse light and an optical amplifier using the same. <P>SOLUTION: The ultrashort pulse light with a waveform A from a laser element is rotated by a polarization beam splitter 2 and a Faraday rotator 3. The ultrashort pulse light passes through a 1st half-wavelength plate 4 and is reflected by a mirror 5, passed through a cylindrical lens 6, and amplified by an amplifier 7 excited by an exciting diode, and then the light passes through a cylindrical lens 8 of a next stage, a 2nd half-wavelength plate 9, and a lens 10, and is incident on the phase conjugate mirror for ultrashort pulse light through a mirror 22, a lens 23, and a mirror 24. Signal light from the mirror 24 is incident on a solid-state medium 11, passes through a 1st lens 12, and is reflected by a mirror 14 and further by a mirror 15, passes through a 2nd lens 13 and impinges on the solid-state medium 11 again, so that the light is projected as a phase conjugate wave. The projected light passes through the same route reversely and is further amplified by the amplifier 7 and rotated by the Faraday rotator 3, and then an output of ultrashort pulse light with a waveform B is obtained from the polarization beam splitter 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a phase conjugate mirror for ultrashort pulse light capable of obtaining a high-power laser that can be used for precision machining, and an optical amplifier using the phase conjugate mirror.
[0002]
[Prior art]
In recent years, precision processing with an ultrashort pulse laser has attracted attention, but the output of the ultrashort pulse laser oscillator itself is at most several W. For this reason, an amplifier is generally combined to increase the output. Conventionally, various types of wavefront compensation using a phase conjugate mirror have been proposed and realized in the nanowave and CW (continuous wave) regions.
[0003]
The generation of the phase conjugate wave is the same as the real image reproduction of the recorded hologram. The outline is shown in FIG. 1, in which the signal light E ₁ , the forward pumping light E ₂ , and the backward pumping light E ₃ are incident on the solid medium, so that the hologram of the phase conjugate wave E ^* E ₂ E ₃ is obtained. Is reproduced as a real image. It is also called a real-time hologram in the sense of a hologram that performs recording and reproduction simultaneously.
[0004]
As shown in the basic diagram of the optical amplifier using the phase conjugate mirror shown in FIG. 2, the phase conjugate wave obtained by reversing the signal light with the phase conjugate mirror is time-reversed light, unlike the normal reflected wave. There is a nature to return to the state of. As a result, the incident signal light, which is clean light but low in power, is reflected by the phase conjugate mirror, so that there was no distortion when the wave front is distorted (for example, an amplifier amplified by excitation energy) once. Thus, the original wavefront is restored, but the intensity and amplitude do not return to the original, and the amplified light with high power is emitted with clean light.
[0005]
As shown in FIG. 11, a conventionally used phase conjugate mirror is composed of, for example, only a solid medium 11 of Rh: BaTiO _{3. When} a signal from a laser is incident, a rough hologram and a fine hologram are formed in the solid medium 11. A hologram is generated, and a phase conjugate wave that is a combination of the holograms is emitted. In this type, as shown in FIG. 12, the available gain is only in the range where the spectral width is about 0.4 nm.
[0006]
Such a phase conjugate mirror is used to perform wavefront compensation by a phase conjugate mirror in the nanowave or CW (continuous wave) region. In particular, quartz glass is used as a solid medium SBS phase conjugate mirror for a high-power laser. An invention related to an output laser pulse phase compensation device has also been proposed (see, for example, Patent Document 1). This invention is intended for nanowaves using stimulated Brillouin scattering, and is an ultrashort pulse light of picoseconds. It is not intended for.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-149098
[Problems to be solved by the invention]
As described above, although the output of the laser beam that has passed through the amplifier is large, the frequency bandwidth of the generated phase conjugate wave is narrower than the incident pulse due to the spectral filtering effect (wavelength selectivity) exhibited by the phase conjugate mirror. In addition, the pulse width is widened, and useful information contained in the incident pulse is cut, and the deterioration of the beam quality is unavoidable, and it shows a practical level reflectivity for picosecond ultrashort pulse light There was no phase conjugate mirror.
[0009]
Ultra-short pulse light has a wide spectral width, so the pulse width may widen, or light may not return from the phase conjugate mirror, which may reduce the reflectivity. Requires a wide gain band to operate. Therefore, an object of the present invention is to provide a phase conjugate mirror for ultrashort pulse light and an optical amplifier using the same.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a phase conjugate mirror for ultrashort pulse light according to claim 1 of the present invention comprises a solid medium of a photorefractive material into which signal light from a laser element is incident, and a focal length f A first lens; a second lens having a focal length f; a mirror of the first lens; and a mirror of the second lens, wherein the first lens and the second lens are the center of a solid medium. And the first lens and the second lens are arranged at an angle θ relative to each other, the first lens, the mirror of the lens, the second lens, and the lens. An external resonator was constructed with this mirror.
[0011]
As a result, the phase conjugate mirror for ultrashort pulse light according to the present invention has an external resonator by adding an equal-magnification imaging optical system to the outside so that the beam overlap of the probe light and the counter excitation light is good. In other words, a clean signal light of an ultrashort pulse is time-reversed by a phase conjugate mirror, and the original state where the phase conjugate wave is incident is returned.
[0012]
Phase conjugate mirror for the ultrashort pulse light according to the second aspect of the invention, a solid medium of the photorefractive material, a first lens having a focal length f _2, a second lens having a focal length f _2, a mirror of the first lens consists of a lens of the second lens, the first lens and the second lens is centered spaced apart by the focal length f ₂ of each of the solid medium, said The first lens and the second lens are arranged at an angle θ, and in front of the solid medium, a diffraction grating or a prism on which signal light of a different wavelength is incident from a laser element and a third having a focal length f ₁ A lens is disposed, and the third lens is disposed at a focal distance f ₁ from the center of the prism and the center of the solid medium, and the first lens, the mirror of the lens, and the second lens And an external resonator with the mirror of the lens A phase-conjugate mirror for ultrashort pulse light separated by length is constructed.
[0013]
As a result, the phase conjugate mirror for ultrashort pulse light according to the present invention has an external resonator by adding an equal-magnification imaging optical system to the outside so that the beam overlap of the probe light and the counter excitation light is good. The wavelength can be spatially separated using a diffraction grating or a prism and a lens so that light of different wavelengths can be recorded at different positions for each wavelength, thereby reducing the contrast of the entire hologram. It is possible to prevent this, and the original state in which the phase conjugate wave for each wavelength obtained by reversing the time of the ultrashort pulse clean signal light with the phase conjugate mirror is returned.
[0014]
A phase conjugate mirror for ultrashort pulse light according to claim 3 of the present invention is a photorefractive material solid medium into which signal light from a laser element is incident, a first concave mirror, a second concave mirror, The reflecting mirror is disposed at a focal distance away from the first concave mirror and the second concave mirror, and is externally provided by the first concave mirror, the second concave mirror, and the reflective mirror. A resonator was constructed.
[0015]
As a result, the phase conjugate mirror for ultrashort pulse light according to the present invention has an external resonator by adding an equal-magnification imaging optical system to the outside so that the beam overlap of the probe light and the counter excitation light is good. The phase conjugate wave, which is time-reversed by a phase conjugate mirror, is returned to the original state when the ultrashort pulse clean signal light is incident. Reflective optics without using a refractive optical element in the imaging optical system An element can also be used.
[0016]
A phase conjugate mirror for ultrashort pulse light according to a fourth aspect of the present invention includes a solid medium of a photorefractive material, a first concave mirror, a second concave mirror, and a reflecting mirror. The first concave mirror and the second concave mirror are spaced apart from each other by a focal length, and a diffraction grating or prism in which signal lights of different wavelengths are incident from a laser element and a third are disposed in front of the solid medium. The first concave mirror, the second concave mirror and the reflecting mirror constitute an external resonator to constitute a phase conjugate mirror for ultrashort pulse light separated for each wavelength.
[0017]
As a result, the phase conjugate mirror for ultrashort pulse light according to the present invention can use a reflecting optical element instead of a refractive optical element in the imaging optical system, and add an equal magnification imaging optical system to the outside. By configuring an external resonator, the beam overlap between the probe light and the counter excitation light can be improved, and a diffraction grating or prism can be used so that holograms can be recorded at different positions for different wavelengths of light. The lens is used to spatially separate the wavelengths to prevent a decrease in the contrast of the entire hologram, and phase conjugate waves for each wavelength, which are time-reversed by ultra-short pulsed signal light using a phase conjugate mirror, are incident. It will be returned to its original state.
[0018]
The phase conjugate mirror for ultrashort pulse light according to claim 5 of the present invention is the phase conjugate mirror for ultrashort pulse light according to any of claims 1 to 4, wherein the solid medium of the photorefractive material is , Rh: BaTiO ₃ , Ce: BaTiO ₃ , Co: BaTiO ₃ , Mg: LiNbO ₃ , Sn ₂ P ₂ S ₆ .
[0019]
A phase conjugate mirror for ultrashort pulse light according to a sixth aspect of the present invention is the phase conjugate mirror for ultrashort pulse light according to the first to fourth aspects, wherein the laser element is Nd: One of YAG, Nd: YVO ₄ , Nd: KGd (WO ₃ ) ₂ , Nd: YLF, Nd: YAl ₃ (BO ₃ ) ₄ , Yb: YAG, Yb: KGd (WO ₃ ) ₂ is used. It was characterized by that.
[0020]
As a result, by selecting a material exhibiting the photorefractive effect and a material exhibiting the saturation amplification effect, the ultrashort pulse light is a very short pulse and cannot be followed by a normal phenomenon. It is possible to realize an element capable of recording a phenomenon caused by a pulse by time integration.
[0021]
An optical amplifier using a phase conjugate mirror for ultrashort pulse light according to a seventh aspect of the present invention includes a laser light source as an input signal source, a deflecting beam splitter, a Faraday rotator, and a first half-wave plate. A mirror, a first cylindrical lens, an amplifier excited by an excitation diode, a second cylindrical lens, a second half-wave plate, a lens, and a phase conjugate mirror for ultrashort pulse light And these are sequentially connected so that output light is emitted from the deflecting beam splitter.
[0022]
An optical amplifier using a phase conjugate mirror for ultrashort pulse light according to an eighth aspect of the present invention includes a laser light source as an input signal source, a deflecting beam splitter, a Faraday rotator, and a first half-wave plate. A mirror, a first cylindrical lens, an amplifier excited by an excitation diode, a second cylindrical lens, a second half-wave plate, a lens, and a phase conjugate mirror for ultrashort pulse light And a phase conjugate mirror for the ultrashort pulse light, wherein the output light is emitted from the deflecting beam splitter. A configuration using such a phase conjugate mirror was adopted.
[0023]
This makes it possible to improve the beam overlap between the probe light and the counter excitation light by adding an equal-magnification imaging optical system to the outside and constructing an external resonator. The phase conjugate wave that is time-reversed by the conjugate mirror is returned to its original state, and the intensity and amplitude are amplified by making a round trip through a medium that distorts the wavefront such as an amplifier that is amplified by excitation energy. Returning to the original wavefront as if there was no distortion, the amplified light is emitted with clean light and high power.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
A hologram that can be used as a phase conjugate mirror for ultrashort pulse light according to the present invention will be described below. In the hologram generated when the signal light and the reference light are incident on the solid medium of the photorefractive material in FIG. 3, the gain when the hologram interval is Λ, the coupling coefficient or the two-wave mixing gain coefficient is κ, and the contrast of the interference fringes is m. If the spectrum width is Δλ, there is a relationship of the following equation.
[Expression 1]
Δλ∝mκΛ ²
[0025]
Therefore, in order to increase the gain spectrum width Δλ, it is preferable to select a material having a large κ, increase the hologram interval Λ, and increase the contrast m of the interference fringes. In order to increase the hologram interval Λ, a phase conjugate mirror having an external resonator is used. As a material having a large κ, photorefractive materials Rh: BaTiO ₃ , Ce: BaTiO ₃ , Co: BaTiO ₃ , Mg: LiNbO _{3 are used.} Sn ₂ P ₂ S ₆ may be used as a phase conjugate mirror using a photorefractive effect. Phase conjugate mirrors using photorefractive effect using these materials cause phenomena with the average power of light (not instantaneous light intensity), so the device itself is slow, but time integration Even ultra-short pulse light can be used.
[0026]
Next, an embodiment of a phase conjugate mirror for ultrashort pulse light according to the present invention will be described with reference to the drawings. FIG. 4 shows a first embodiment of a phase conjugate mirror having an external resonator according to the present invention. In the figure, 11 is a solid medium of the photorefractive material, 12 is a first lens having a focal length f, 13 is a second lens having a focal length f, 14 is a mirror M1 of the first lens 12, and 15 is a second lens. This is a mirror M2 of the lens 13. The first lens 12 and the second lens 13 are arranged apart from the center of the solid medium 11 by a focal length f. Further, the first lens 12 and the second lens 13 are disposed at an angle θ and a distance of approximately 2f.
[0027]
The first lens 12 and the mirror 14 and the second lens 13 and the mirror 15 constitute an external resonator. Signal light from a laser element, which is a laser light source, first enters the solid medium 11, is reflected by the mirror 14 through the first lens 12, is further reflected by the mirror 15, and passes through the second lens 13. The light again enters the solid medium 11 and is output as a phase conjugate wave. In this way, by adding an equal-magnification imaging optical system outside to form an external resonator, the beam overlap of the probe light and the counter excitation light can be improved. The passage of the signal light is the same in the route from the second lens 13 through the first lens 12.
[0028]
As the laser element at this time, Nd: YAG, Nd: YVO ₄ , Nd: KGd
(WO ₃ ) ₂ , Nd: YLF, Nd: YAl ₃ (BO ₃ ) ₄ , Yb: YAG, Yb: KGd (WO ₃ ) ₂ are suitable.
[0029]
Here, Formula 1 can be converted into the following formula.
[Expression 2]
Δλ∝mκ (λ / 2sinθ) ²
[0030]
As a result, by selecting a material having a large κ, the hologram interval Λ can be increased and the contrast of interference fringes can be increased. The gain spectrum width Δλ can be increased as the angle θ between the first lens 12 and the second lens 13 decreases. As shown in FIG. 5, the gain spectrum characteristic of the phase conjugate mirror of the present invention can be expanded in the range where the spectrum width is about 1 nm.
[0031]
A second embodiment of a phase conjugate mirror having an external resonator according to the present invention will be described with reference to FIG. This is a phase conjugate mirror having an external resonator of ultrashort pulsed light having a plurality of wavelengths, using a hologram (so-called spectral hologram) that is spatially separated for each wavelength. Since ultrashort pulse light is light having a wide spectral width, if light of different wavelengths records a photogram at the same position, the holograms for each wavelength cancel each other, and the contrast of the entire hologram is lowered. Therefore, the wavelength is spatially separated using a diffraction grating or a prism and a lens so that a hologram can be recorded at a different position for each wavelength. Components equivalent to those in FIG.
[0032]
6, the solid medium of the photorefractive material 11, 12 is a first lens having a focal length _{f 2,} a second lens having a focal length _{f 2} is 13, the 14 mirrors the first lens 12 M1,15 Is a mirror M2 of the second lens 13. A first lens 12 and the second lens 13 are spaced apart by the focal length f ₂ from the center of each of the solid medium 11. The first lens 12 and the second lens 13 are disposed at an angle θ and a distance of approximately 2f _{2 with} respect to each other.
[0033]
In front of the solid medium 11, the third lens 17 of the diffraction grating or prism 16 and the focal length f ₁ it is placed. The lens 17 is disposed at a focal distance f ₁ from the center of the prism 16 and the center of the solid medium 11.
[0034]
The first lens 12 and the mirror 14 and the second lens 13 and the mirror 15 constitute an external resonator. Signal lights having different wavelengths λ ₁ , λ ₂ , and λ ₃ from a laser element that is a laser light source are separated through a prism 16 and incident on a solid medium 11 through a third lens 17 having a focal length f ₁ . The
[0035]
Light from the solid medium 11 is reflected by the mirror 14 through the first lens 12, is further reflected by the mirror 15, and is incident on the solid medium 11 again through the second lens 13. In the solid medium 11, a hologram for each signal light having different wavelengths λ ₁ , λ ₂ , and λ ₃ is formed, each wavelength component is fed back to the prism 16 through the third lens 17, and a different wavelength λ is transmitted by the prism 16. ₁ , λ ₂ , and λ ₃ are separated and output as phase conjugate waves. In this way, by adding the same-magnification imaging optical system to the outside and configuring the external resonator, the beam overlap of the probe light and the counter excitation light can be improved, and the contrast of the entire hologram can be prevented from being lowered.
[0036]
An embodiment of a phase conjugate mirror using a reflective optical system will be described with reference to FIG. 7 as a third embodiment of the present invention. In the figure, 11 is a solid medium of the photorefractive material, 18 is a first concave mirror, 19 is a second concave mirror, and 20 is a reflecting mirror. The reflecting mirror 20 is arranged so as to be separated from the first concave mirror 18 and the second concave mirror 19 by their respective focal lengths.
[0037]
The first concave mirror 18, the second concave mirror 19 and the reflecting mirror 20 constitute an external resonator. Signal light from a laser element that is a laser light source is first incident on the solid medium 11, reflected by the reflecting mirror 20 through the first concave mirror 18, further reflected by the second concave mirror 19, and again reflected on the solid medium 11. Incident and phase conjugate is output as In this way, by adding an equal-magnification imaging optical system outside to form an external resonator, the beam overlap of the probe light and the counter excitation light can be improved. The passage of the signal light is the same in the route from the second concave mirror 19 through the first concave mirror 18.
[0038]
Another embodiment of a phase conjugate mirror using a reflective optical system will be described as a fourth embodiment of the present invention with reference to FIG. This is a phase conjugate mirror having an external resonator of ultrashort pulsed light having a plurality of wavelengths, using a hologram (so-called spectrum hologram) that is spatially separated for each wavelength. The phase conjugate mirror of the present invention shown in FIG. It is a deformation.
[0039]
In the figure, 11 is a solid medium of the photorefractive material, 18 is a first concave mirror, 19 is a second concave mirror, and 20 is a reflecting mirror. The reflecting mirror 20 is arranged so as to be separated from the first concave mirror 18 and the second concave mirror 19 by their respective focal lengths. A third concave mirror 21 with a diffraction grating or prism 16 is disposed in front of the solid medium 11.
[0040]
Signal lights having different wavelengths λ ₁ , λ ₂ , and λ ₃ from a laser element that is a laser light source are separated through a prism 16 and are incident on a solid medium 11 through a third concave mirror 21. The light from the solid medium 11 is reflected by the reflecting mirror 20 through the first concave mirror 18, and is incident again on the solid medium 11 through the second concave mirror 19. In the solid medium 11, a hologram for each signal light having different wavelengths λ ₁ , λ ₂ , and λ ₃ is formed, each wavelength component is fed back to the prism 16 through the third concave mirror 21, and the wavelength 16 having a different wavelength λ ₁ , λ ₂ , and λ ₃ are separated and output as phase conjugate waves.
[0041]
Next, an embodiment of an optical amplifier using the phase conjugate mirror for ultrashort pulse light according to the present invention will be described with reference to FIG. In the figure, 1 is a phase conjugate mirror for ultrashort pulse light, 2 is a deflecting beam splitter, 3 is a Faraday rotator, 4 is a first half-wave plate, 5 is a mirror, 6 is a first cylindrical lens, 7 Is an amplifier excited by an excitation diode, 8 is a second cylindrical lens, 9 is a second half-wave plate, and 10 is a lens.
[0042]
Ultra short pulse light (for example, 30 mW, 7 ps) having a waveform A from the laser element is deflected by 45 ° by the deflecting beam splitter 2 and then further rotated by 45 ° by the Faraday rotator 3. The ultrashort pulse light is reflected by the mirror 5 through the first half-wave plate 4, is amplified by the amplifier 7 that is excited by the excitation diode via the cylindrical lens 6, and is amplified by the next cylindrical lens 8. The light enters the phase conjugate mirror 1 for ultrashort pulse light through the two half-wave plates 9 and the lens 10.
[0043]
The action of the light in the phase conjugate mirror 1 for ultrashort pulse light is as described above, and the light emitted from the phase conjugate mirror 1 passes through the reverse route, and is further amplified by the amplifier 7, so that the Faraday rotator 3 After that, the output of the ultrashort pulse light (for example, 6 W, 7 ps) having the waveform B is obtained from the deflecting beam splitter 2. As a result, it is possible to realize ultrashort pulse light having the same pulse width and a large amplitude.
[0044]
A specific embodiment of the optical amplifier will be described with reference to FIG. 10, taking the phase conjugate mirror for ultrashort pulse light of the present invention described in FIG. 4 as an example. In the figure, the same components as those in FIGS. 4 and 9 are denoted by the same reference numerals.
[0045]
Ultra short pulse light (for example, 30 mW, 7 ps) having a waveform A from the laser element is deflected by 45 ° by the deflecting beam splitter 2 and then further rotated by 45 ° by the Faraday rotator 3. The ultrashort pulse light is reflected by the mirror 5 through the first half-wave plate 4, is amplified by the amplifier 7 that is excited by the excitation diode via the cylindrical lens 6, and is amplified by the next cylindrical lens 8. The light passes through the half-wave plate 9 and the lens 10 and enters the phase conjugate mirror for ultrashort pulse light through the mirror 22, the lens 23, and the mirror 24.
[0046]
As shown in FIG. 4, the signal light from the mirror 24 is first incident on the solid medium 11 and reflected by the mirror 14 through the first lens 12. Then, it is further reflected by the mirror 15, passes through the second lens 13, enters the solid medium 11 again, and exits as a phase conjugate wave.
[0047]
The light emitted from the solid medium 11 of the phase conjugate mirror passes through the reverse route and is further amplified by the amplifier 7 and rotated by 45 ° by the Faraday rotator 3 (the Faraday rotator is one regardless of the direction of light). The rotation direction of the direction is indicated), and the output of the ultrashort pulse light (for example, 6 W, 7 ps) having the waveform B is obtained from the deflection beam splitter 2. As a result, it is possible to realize ultrashort pulse light having the same pulse width and a large amplitude.
[0048]
In this way, the above-described external resonance type phase conjugate mirror of the present invention is applied in place of the phase conjugate mirror 1 for ultrashort pulse light of FIG. 9, and the phase conjugate mirror for ultrashort pulse light of the present invention is applied. The optical amplifier used can be realized.
[0049]
【The invention's effect】
As described above, the phase conjugate mirror for ultrashort pulse light according to the present invention can widen the hologram interval recorded in the phase conjugate mirror, and adds a resonator as an equal magnification imaging optical system to the outside. Thus, the beam overlap between the probe light and the counter excitation light can be improved. In addition, spectral separation of incident light using a diffraction grating or prism, etc., and recording the diffraction grating at different positions of the phase conjugate mirror (spectrum hologram), separates the conjugate wave for each ultrashort pulse light of different wavelength can do.
[0050]
The optical amplifier using the phase conjugate mirror for the ultrashort pulse light according to the present invention reduces the spectral filtering effect (wavelength selectivity) of the phase conjugate mirror and exhibits a high reflectivity even for the ultrashort pulse light. A conjugate mirror can be realized. As a result, it is possible to realize an ultrashort pulse laser with high output and high beam quality approaching the diffraction limit, and it is possible to realize ultrashort pulse light having a large amplitude only with a pulse width unchanged.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of real image reproduction of a hologram.
FIG. 2 is a basic diagram of an optical amplifier using a phase conjugate mirror.
FIG. 3 is a hologram generated when signal light and reference light are incident on a solid medium.
FIG. 4 is a diagram showing a first embodiment of a phase conjugate mirror having an external resonator according to the present invention.
FIG. 5 is a gain spectrum characteristic diagram of the phase conjugate mirror of the present invention.
FIG. 6 is a diagram showing a second embodiment of a phase conjugate mirror having an external resonator according to the present invention.
FIG. 7 is a diagram showing a third embodiment of a phase conjugate mirror using the reflection optical system of the present invention.
FIG. 8 is a diagram showing a fourth embodiment of a phase conjugate mirror using the reflection optical system of the present invention.
FIG. 9 is an embodiment diagram of an optical amplifier using the phase conjugate mirror of the present invention.
FIG. 10 is a specific embodiment diagram of an optical amplifier using the phase conjugate mirror of the present invention.
FIG. 11 is a configuration diagram of a conventional phase conjugate mirror.
FIG. 12 is a gain spectrum diagram of a conventional phase conjugate mirror.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Phase conjugate mirror 2 Deflection beam splitter 3 Faraday rotator 4, 9 Half-wave plate 5, 14, 15
22, 23 Mirror 6, 8 Cylindrical lens 7 Amplifier 10 Lens 11 Solid medium 12, 13,
17, 23 Lens 16 Diffraction grating or prism 18, 19, 21 Concave mirror 20 Reflector

Claims (8)

A solid medium of a photorefractive material into which signal light from a laser element is incident, a first lens having a focal length f, a second lens having a focal length f, a mirror of the first lens, and a second lens The first lens and the second lens are spaced apart from each other by a focal length f from the center of the solid medium, and the first lens and the second lens are at an angle θ with respect to each other. A phase conjugate mirror for ultrashort pulse light, wherein the first lens, the mirror of the lens, and the second lens and the mirror of the lens constitute an external resonator. Consists of a solid medium of the photorefractive material, a first lens having a focal length f _2, a second lens having a focal length f _2, a mirror of the first lens, a mirror of the second lens, said The first lens and the second lens are disposed at a focal distance f ₂ from the center of the solid medium, and the first lens and the second lens are disposed at an angle θ with respect to each other. A diffraction grating or a prism on which signal lights of different wavelengths are incident from a laser element and a third lens with a focal length f ₁ are arranged in front of the third lens, and the third lens has a center of the prism and a center of a solid medium. They are spaced apart by the focal length f ₁ of each from, characterized by comprising constituting the external resonator with a mirror of the mirror and the second lens and the lens of the first lens and the lens Phase for ultrashort pulse light separated by wavelength Conjugate mirror. A solid medium of a photorefractive material into which signal light from a laser element is incident, a first concave mirror, a second concave mirror, and a reflecting mirror, and the reflecting mirror includes the first concave mirror and the second concave mirror. A phase for ultrashort pulse light, which is arranged to be separated from the concave mirror by a respective focal length, and an external resonator is constituted by the first concave mirror, the second concave mirror and the reflecting mirror. Conjugate mirror. A solid medium of photorefractive material, a first concave mirror, a second concave mirror, and a reflecting mirror, the reflecting mirrors being separated from the first concave mirror and the second concave mirror by respective focal lengths. In front of the solid medium, a diffraction grating or a prism and a third concave mirror into which signal lights of different wavelengths are incident from a laser element are arranged, the first concave mirror, the second concave mirror, and the reflection A phase conjugate mirror for ultrashort pulse light separated for each wavelength, wherein an external resonator is constituted by a mirror. The solid medium of the photorefractive material is any one of Rh: BaTiO ₃ , Ce: BaTiO ₃ , Co: BaTiO ₃ , Mg: LiNbO ₃ , and Sn ₂ P ₂ S _6. 5. A phase conjugate mirror for ultrashort pulse light according to claim 4. As the laser element, Nd: YAG, Nd: YVO ₄ , Nd: KGd (WO ₃ ) ₂ , Nd: YLF, Nd: YAl ₃ (BO ₃ ) ₄ , Yb: YAG, Yb: KGd (WO ₃ ) ₂ 5. The phase conjugate mirror for ultrashort pulse light according to claim 1, wherein any one of the above is used. A laser light source as an input signal source, a deflecting beam splitter, a Faraday rotator, a first half-wave plate, a mirror, a first cylindrical lens, an amplifier excited by an excitation diode, and a second cylindrical A lens, a second half-wave plate, a lens, and a phase conjugate mirror for ultrashort pulse light, which are sequentially connected, and output light is emitted from the deflection beam splitter. An optical amplifier using a phase conjugate mirror for ultrashort pulse light. The phase conjugate mirror according to any one of claims 1 to 6, wherein the phase conjugate mirror according to any one of claims 1 to 6 is used as the phase conjugate mirror for the ultrashort pulse light. An optical amplifier using a conjugate mirror.

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