JP2000187167A - Wide band spatial optical phase modulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely control distributed compensation regardless of intensity of laser beam power in a wide wavelength region by providing a tilt angle changing means which changes an inclination of a parallel flat plate composed of an optical transmitting material. SOLUTION: When a quartz parallel flat plate 18 is made incident with short pulse laser beams, first, a prescribed voltage is applied to a bimorph piezo-actuator 20 by electric control from a controller 24, and the bimorph piezo-actuator 20 is distorted in accordance with a tension of the applied voltage to bend in the direction of the arrow A. Since the bimorph piezo-actuator 20 is bent in the direction of the arrow A, the quartz parallel flat plate 18 is inclined in the direction of the arrow B. That is, a spatial phase modulation is imparted to the laser beams transmitting those by independently and moreover optionally changing the inclination of the quartz parallel flat plate 18. Thus, the pulse width of the laser beams transmitting the quartz parallel flat plate 18 is compressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide-band spatial light phase modulator, and more particularly, to a pulse width ranging from about femtoseconds ( ^10-15 seconds) to picoseconds ( ^10-12 seconds).
A wide-band spatial light phase modulator suitable for use in compressing the pulse width of a short pulse laser beam, for example, X
The intensity of the excitation laser required to generate soft X-ray coherent light, which is the light source of the X-ray microscope, is increased, the pulse is shortened, or when processing difficult-to-process materials using ablation, various wavelengths are used. Broadband spatial light phase modulation suitable for manipulating the pulse waveform of laser light into an arbitrary shape or using high-intensity short-pulse laser light for creating new materials by ultrafast chemical reactions About the vessel.

[0002]

2. Description of the Related Art Conventionally, in the process of generating and using high-intensity short-pulse laser light such as a titanium-sapphire laser, a technique of compressing the pulse width has been an important position.

That is, it is essential that a short pulse laser beam having a pulse width on the order of femtoseconds to picoseconds has a wide spectrum width in inverse proportion to the pulse width. In, there is a need for a pulse compression technique for controlling the phase of each wavelength component of a wide spectrum.

Further, it is known that the pulse width of this short-pulse laser beam is extended by chromatic dispersion when transmitted or propagated through a substance.
In various applications of short-pulse laser light, it is necessary to recompress the pulse width thus extended.

[0005] For this reason, as a method of generating a short-pulse laser beam by compressing a pulse having a wide spectrum as described above, but having a pulse width not sufficiently compressed, there is a method of transmitting through a substance, Alternatively, various techniques have been proposed as a technique for recompressing the pulse width of a short pulse laser beam that has been extended during propagation or returning to the original pulse width. It is known to use a prism pair composed of the above-described prisms, a diffraction grating pair composed of two diffraction gratings, a chirp mirror, a spatial light phase modulator using liquid crystal, or the like.

Here, in a prism pair composed of two prisms and a diffraction grating pair composed of two diffraction gratings, dispersion compensation is performed by using such a prism pair and a diffraction grating pair, so that a short pulse laser beam can be obtained. Is intended to compress the extended pulse width.

However, using a prism pair, a short pulse
When the pulse width of the laser light is compressed, there is a problem that only low-order dispersion in a limited range determined by the characteristics of the prism can be compensated.

Further, in the case where the pulse width of the short pulse laser beam is compressed by using the prism pair, when the power intensity of the short pulse laser beam increases, the short pulse laser beam passes through the prism pair. Another problem is that the pulse width is extended again by the self-phase modulation of the short pulse laser light.

Also, when the pulse width of the short-pulse laser light is compressed by using a diffraction grating pair consisting of two diffraction gratings, it is determined by the characteristics of the diffraction grating as in the case of the above-described prism pair. There has been a problem that only low-order dispersion in a limited range can be compensated.

Further, when the pulse width of the short pulse laser beam is compressed by using a diffraction grating pair composed of two diffraction gratings, the loss of the short pulse laser beam in the diffraction grating pair becomes so large that it cannot be ignored. However, there is a problem that the energy of the short-pulse laser light after the compression of the pulse width is greatly reduced.

A technique for solving the problems of the above-mentioned prism pair and diffraction grating pair which has been known in recent years is a dispersion compensation mirror called a chirp mirror.

However, when the pulse width of the short-pulse laser beam is compressed using the chirp mirror, the wavelength range of the short-pulse laser beam is limited by the raw material of the chirp mirror and the manufacturing process of the chirp mirror.
There is a problem that it can be used only for short-pulse laser light in the wavelength range in the limited range.

By the way, as chirp mirrors which can be used at present, only those used in a wavelength range from a visible region to a near-infrared region have been manufactured. In addition, a short-pulse mirror using a spatial light phase modulator using liquid crystal is used. When the pulse width of the laser light is compressed, there is a problem that it cannot be used for a short pulse laser light having a high peak power because the optical damage threshold of the liquid crystal is low.

Further, when a pulse width of a short pulse laser beam is compressed by using a spatial light phase modulator using a liquid crystal, it is limited to a range from a visible region to a near infrared region due to the optical properties of the liquid crystal. However, there is a problem that it can be used only for short-pulse laser light in the wavelength range.

As described above, in order to generate a short-pulse laser beam by compressing a pulse having a broad spectrum but a pulse width not sufficiently compressed, or to transmit or propagate through a substance. The pulse width of the short pulse laser beam
Wideband spatial light phase modulator using known prism pairs, diffraction grating pairs, chirped mirrors or liquid crystals used to compress to return to the original unstretched pulse width before transmitting or propagating through the material All have various problems as described above.

That is, the problems are that the pulse width is re-extended by self-phase modulation of the short pulse laser beam in the prism pair, the energy of the short pulse laser beam is reduced after the pulse width compression in the diffraction grating pair, the prism pair and Low-order dispersion compensation in a diffraction grating pair, limitations on the usable wavelength range in a chirped mirror and a liquid crystal-based spatial light phase modulator, and restrictions on the usable laser light power in a liquid crystal-based spatial light phase modulator. there were.

That is, as a method of generating a short-pulse laser beam by compressing a pulse having a broad spectrum but a pulse width not sufficiently compressed, or transmitting or propagating through a substance. The pulse width of the short pulse laser beam
As a method of compressing to return to the original non-stretched pulse width before transmitting or propagating a substance, various methods have been conventionally proposed as described above, but precise control of dispersion compensation is required. There are problems that it is difficult, that it cannot be used in a wide wavelength range, and that it cannot be used irrespective of the strength of the laser light.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to generate a short pulse laser beam. In addition, when recompressing the pulse width of a short pulse laser beam that has been extended while transmitting or propagating through a substance, dispersion compensation can be precisely controlled, and a wide range can be obtained. It is an object of the present invention to provide a wide-band spatial light phase modulator which can be used in a wavelength region and can be used regardless of the power of laser light.

[0019]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention enables precise control of dispersion compensation in a wide wavelength range regardless of the power of laser light. .

That is, according to the first aspect of the present invention, a plurality of parallel plane plates made of an optically transmissive material and the parallel plane plates are aligned and supported in a spatially movable state. And an inclination changing means for changing the inclination of the plane-parallel plate.

Here, the "plurality of parallel plane plates made of optically transmissive material" corresponds to the "parallel plane plate 18" in the section of "Embodiments of the Invention", and the "support means" described above. Corresponds to the “supporting column 12”, the “shaft 14” and the “bearing cylinder 16” in the section of “Embodiment of the Invention”, and the above-mentioned “inclination changing means” corresponds to the section of “Embodiment of the Invention”. This corresponds to “bimorph piezo actuator 20”.

According to a second aspect of the present invention, in the first aspect of the present invention, the parallel flat plate is made of quartz.

That is, the invention according to claim 2 of the present invention is based on the idea that a solid material is suitable for constituting the plane-parallel plate.

According to a third aspect of the present invention, in accordance with the first aspect of the present invention, the inclination changing means is provided for each of the parallel plane plates. The parallel plane plates are independently and arbitrarily tilted by the tilt changing means, so that the laser light passing through each of the parallel plane plates has an independent and arbitrary phase. It is intended to give a change.

Therefore, according to the third aspect of the present invention, each of the parallel plane plates is independently and arbitrarily inclined by the inclination changing means, and a laser beam transmitted through each of the parallel plane plates is provided. By giving independent and arbitrary phase changes to the light, spatial phase modulation is given to the light transmitted across the plurality of parallel plane plates.

According to a fourth aspect of the present invention, there is provided the invention according to any one of the first, second or third aspects of the present invention, further comprising a laser beam incident on the parallel plane plate. It has wavelength dispersion means for wavelength-dispersing light, and when the laser light of each wavelength wavelength-dispersed of the laser light incident by the wavelength dispersion means is incident on the parallel plane plate, independent of each wavelength component and By giving an arbitrary phase change, compression of the pulse width, extension of the pulse width, or control of the pulse waveform are performed.

Therefore, according to the fourth aspect of the present invention, the laser light incident on the plane-parallel plate is dispersed into the laser light of each wavelength by the wavelength dispersion means, and the laser light of each wavelength is dispersed. When the laser light is incident on each of the parallel plane plates, an independent and arbitrary phase change is given to each wavelength component by each of the parallel plane plates, and the pulse width is compressed, or, or the pulse width is extended, or , The pulse waveform is controlled.

According to a fifth aspect of the present invention, there is provided the invention according to any one of the first, second or third aspects of the present invention, further comprising a laser beam transmitted through the plane-parallel plate. It has a light condensing means for condensing, and the laser light transmitted through the parallel plane plate is condensed on the surface of the solid material by the light condensing means, thereby finely processing a periodic structure on the surface of the solid material. It is like that.

Therefore, according to the fifth aspect of the present invention, the laser beam transmitted through the plane-parallel plate is condensed on the surface of the solid material by the condensing means, so that the solid material is condensed. The periodic structure is finely processed on the surface.

[0030]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a wide-band optical phase modulator according to the present invention;

FIG. 1 is a schematic front view (see FIG. 1 (a)) showing a schematic configuration of an embodiment of a wide-band spatial optical phase modulator according to the present invention, and a schematic side view (FIG. 1 (b)).

In FIG. 1, a broadband spatial light phase modulator 200 according to the present invention has two support columns 12 fixedly arranged upright on the upper surface of a support base 10, and these two support columns are provided. At the upper end of the shaft 12, there is provided a shaft 14 for connecting the two, and on this shaft 14, five bearing cylinders 16 are penetrated and rotatably supported.・ Cylinder 16
Is made movable.

Further, a quartz parallel flat plate 18 is attached to each of the five bearing cylinders 16. That is, in this embodiment, quartz is used as the optically transparent material.

Thus, the parallel plane plates 18 are aligned and supported in a spatially movable state.

A center support member 17 is mounted between the two support columns 12 provided on the support base 12, and the center support member 17 is connected to a controller 24 via a lead wire 22. Five bimorph piezo actuators 20, which are electrically connected and electrically controlled by the controller 24, are provided.

The five quartz parallel plane plates 18 and the five bimorph piezo actuators 20 are arranged corresponding to each other, and each quartz parallel plane plate 1
8 and the upper end of each bimorph piezo actuator 20.

As described above, the bearing cylinder 16 is rotatably supported on the shaft 14 through the shaft 14, that is, the bearing cylinder 16 is rotatable about the shaft 14 as a central axis. is there.

Further, as described above, the quartz parallel plane plate 18 is attached to the bearing cylinder 16, and even when the quartz parallel plane plate 18 is provided,
The bearing cylinder 16 is movable about the shaft 14 as a central axis.

However, in this embodiment, one bearing cylinder 16 is provided with one quartz parallel flat plate 18, and the bearing cylinder 16 provided with such a quartz parallel flat plate 18 is provided. Are used.

The bearing cylinders 16 provided with the quartz plane-parallel plates 18 are independently movable about the shaft 14 as a central axis.

Further, in this embodiment, the quartz plane-parallel plate 18 attached to the bearing cylinder 16 is a plane-parallel plane plate made of quartz and has a width of 2 mm,
It has a length of 20 mm and a thickness of 1 mm.

As shown in FIG. 2, the transmission wavelength range of the quartz light is about 0.15 μm to 3.0 μm, and the transmission wavelength range of the light of the quartz plane-parallel plate 18 is naturally 0.15 μm to 3.0 μm.
μm to 3.0 μm.

The plane-parallel quartz plate 18 is attached to the bearing cylinder 16 and spatially disposed.

As described above, the quartz plane-parallel plate 18
Bearing cylinders 16 each with
Are independently rotatable about the shaft 14, each of the quartz parallel flat plates 18 attached to each bearing cylinder 16 is also independent about the shaft 14. It is made rotatable.

Here, the bimorph piezo actuator 20 functions as an inclination changing means for changing the inclination of the quartz parallel plate 18.

Bimorph Piezo Actuator 2
The lower end of the reference numeral 0 is attached to the center support member 17, and the upper end of each bimorph piezo actuator 20 is in contact with each of the quartz parallel plane plates 18.

The electric control from the controller 24 is performed via the lead wire 22 through the bimorph piezo
When the voltage is applied to the actuator 20, the bimorph piezo actuator 20 is distorted in accordance with the magnitude of the applied voltage and bends in the direction of the arrow A in FIG. 1B.

Since the bimorph piezo actuator 20 is in contact with the quartz parallel plate 18 at the upper end thereof, the bimorph piezo actuator 20
Is applied under the control of the controller 24, and the bimorph piezo actuator 20 bends in the direction of the upper arrow A in FIG. 1 (b). In the direction of.

One bimorph piezo actuator 20 is provided for one quartz plane-parallel plate 18.
Is arranged, the voltage applied to each of the five bimorph piezo actuators 20 is arbitrarily changed under the control of the controller 24, whereby 5
The degree of inclination of each of the two quartz parallel flat plates 18 can be independently and arbitrarily changed.

The case where short pulse laser light is incident on the above-mentioned wide band spatial light phase modulator 200 in the above configuration will be described.

Here, a short pulse pulse is applied to the quartz parallel plate 18.
In order to facilitate understanding of the case where laser light is incident, first, the case where light of wavelength λ is incident on a parallel plane plate having a thickness d made of a certain optically transmissive material will be described.

When light having a wavelength λ is perpendicularly incident on a plane-parallel plate having a thickness d made of an optically transmissive material and propagates through the optically transmissive material, the light having a wavelength λ simply passes through the air. The phase is delayed as compared with the case of propagation. The phase change amount φ is obtained by the following equation: φ = 2πd / λ · (n−n ₀ ) (1)

Here, in the above equation (1), n is the refractive index of the optically transmissive material at the wavelength λ, and n ₀ is the wavelength λ.
Is the refractive index of air.

Then, from the state where the light having the wavelength λ is perpendicularly incident on the plane-parallel plate having a thickness d made of an optically transmissive material,
When the parallel plane plate is tilted so that the light having the wavelength λ is incident on the parallel plane plate at the incident angle θ, the light having the wavelength λ is incident on the parallel plane plate at the incident angle θ.

For this reason, as compared with the case where the light having the wavelength λ is perpendicularly incident on the plane-parallel plate, the distance that the light having the wavelength λ propagates in the plane-parallel plate becomes longer, so that the amount of phase change increases. Will be.

At this time, the relationship between the incident angle θ of the light having the wavelength λ to the parallel plane plate and the phase change amount φ (θ) is as follows: φ (θ) = 2πd / λ · ｛(n ² −n ₀ ² sin obtained by _{^{2 θ) 1/2 -n 0 co sθ}} } ··· (2).

That is, when light having a wavelength λ is incident on a parallel plane plate having a thickness d made of an optically transparent material, the incident angle when the light having a wavelength λ is incident on the parallel plane plate is changed from the vertical to the incident angle. When θ changes to θ, the distance over which the light of wavelength λ propagates in the plane-parallel plate changes, so that the phase change amount changes from φ to φ (θ).
Changes to

Here, the change in the incident angle θ at which the light having the wavelength λ is incident on the parallel plane plate depends on the inclination of the parallel plane plate having a thickness d made of an optically transparent material with respect to the incident light having the wavelength λ. , By changing the inclination of the parallel plane plate, it becomes possible to give an arbitrary amount of phase change to the light passing through each parallel plane plate, and over a plurality of parallel plane plates. Spatial phase modulation is realized for transmitted light.

Even when the laser beam is incident on the quartz plane-parallel plate 18, the inclination of the quartz plane-parallel plate 18 is changed based on the above-described principle.
The laser beam passing through each of the quartz plane-parallel plates 18 can be given an arbitrary phase delay, and the laser beam transmitted over a plurality of plane-parallel plates can be given spatial phase modulation.

Here, when the short-pulse laser beam is incident on the quartz plane-parallel plate 18, first, a predetermined voltage is applied to the bimorph piezo actuator 20 by electrical control from the controller 24. The bimorph piezo actuator 20 is distorted according to the magnitude of the applied voltage and bends in the direction of the arrow A in FIG. 1B.

When the bimorph piezo actuator 20 bends in the direction of the arrow A in FIG. 1B, the quartz plane-parallel plate 18 is inclined in the direction of the arrow B in FIG. 1B.

At this time, the inclination of the plane-parallel quartz plate 18 is
It can be changed independently and arbitrarily by electrical control from the controller 24 in accordance with the incident laser light.

Here, assuming that the thickness d of the quartz plane-parallel plate 18 and the refractive index n of the quartz plane-parallel plate 18 at the wavelength λ and the refractive index n _{0 of the} air at the wavelength λ, the quartz plane-parallel plate 18 The phase delay φ when a short pulse laser beam is perpendicularly incident on the laser beam is obtained by equation (1).

The quartz parallel plane plate 18 has a bimorph
By giving an arbitrary inclination by the piezo actuator 20, the laser beam enters the quartz parallel plate 18 at an incident angle θ, and the relationship between the incident angle θ and the phase delay φ (θ) is as follows. It is obtained by equation (2).

By changing the inclination of the plane-parallel quartz plate 18 independently and arbitrarily, it is possible to apply phase modulation to the laser beam incident on the plane-parallel quartz plate 18.

That is, by independently and arbitrarily changing the inclinations of the five quartz parallel plane plates 18, spatial phase modulation can be applied to the laser light passing therethrough, whereby each quartz parallel plane plate 18 It is possible to compress the pulse width of the laser light passing through the laser beam.

When laser beams having different wavelengths are incident on each of the five quartz parallel plane plates 18 using a dispersive element such as a prism or a diffraction grating, a phase delay different for each wavelength is obtained. That is, a phase change can be given.

In this embodiment, the use of the above-described quartz parallel plane plate 18 makes it possible to precisely control dispersion compensation within the range of quartz transmission wavelength and optical damage threshold. It can be used in the wavelength range from the region to the mid-infrared region, and the power intensity of the laser
Laser light in the range up to 0 ¹¹ W / cm ² can be used.

That is, in this embodiment, the pulse width of the laser beam within the above wavelength range and the power intensity range of the laser beam is adjusted to the precision of dispersion compensation within the transmission wavelength range of quartz and the optical damage threshold. Under control, short-pulse laser light can be generated by compression.

The expanded pulse width of the laser beam within the above-mentioned wavelength range and the power intensity range of the laser beam is compressed so as to return to the original pulse width which has not been extended before transmission and propagation of the substance. can do.

In the above-described embodiment, five quartz parallel flat plates 18 are used. However, the present invention is not limited to this, and an arbitrary number of quartz parallel flat plates 18 may be used. Good.

In the above-described embodiment, the quartz plane-parallel plate 18 made of quartz is used, but the plane-parallel plate may be made of an optically transmissive material. For example, as shown in FIG. Various solid materials having such a transmission wavelength range may be used as the optical transmission material.

In the above-described embodiment, the bimorph piezo actuator 20 is used to change the inclination of the plane-parallel quartz plate 18. However, the present invention is not limited to this, and other means may be used. You may.

Next, referring to FIGS. 3 and 4,
A first application example using the wideband spatial light phase modulator according to the present invention will be described. In the first application example, a broadband spatial light phase modulator according to the present invention is used, for example, to increase the intensity of an excitation laser necessary for generating soft X-ray coherent light, which is a light source of an X-ray microscope, and to shorten the excitation laser. This corresponds to a case where it is used for pulsing or the like.

FIG. 3 is a schematic structural explanatory view of the first applied example described above, and FIG. 4 is a view taken in the direction of arrow C in FIG.

The first application example is a femtosecond laser oscillator 100 that oscillates femtosecond laser light,
A plane mirror 102, a diffraction grating 104 that disperses the femtosecond laser light in wavelength and extracts an outgoing femtosecond laser light, a concave mirror 106 provided with a focal length of the concave mirror 106 from the diffraction grating 104, and a concave mirror 106 from the concave mirror. Folded plane mirror 1 disposed with a focal length
08 and a broadband spatial light phase modulator 200 according to the present invention disposed between the concave mirror 106 and the folded flat mirror 108.
, A beam splitter 110, and an autocorrelator 112.

The femtosecond laser oscillator 100 outputs a femtosecond laser beam as a short-pulse laser beam.
Diffraction grating 10 at an appropriate angle
4 (in this specification, the diffraction grating 104
The femtosecond laser light incident on the laser beam is referred to as “incident femtosecond laser light” as appropriate.)

The diffraction grating 104 disperses the wavelength of the incident femtosecond laser light, and separates and diffracts the light in different directions according to the respective wavelengths. At this time, of the incident femtosecond laser light, the laser light of the short wavelength component is incident on the concave mirror 106 via the path from c to d1, and the incident femtosecond laser light is incident on the concave mirror 106 via the path from c to d2. You.

The concave mirror 106 receives the laser light of each wavelength, which is wavelength-dispersed by the diffraction grating 104. Here, by arranging the interval between the concave mirror 106 and the diffraction grating 104 so as to be equal to the focal length of the concave mirror 106, the femtosecond laser light for each wavelength incident on the concave mirror 106 is emitted as parallel light.

The folding flat mirror 108 is
Are arranged so that the distance between them is equal to the focal length of the concave mirror 106, and folds the parallel light emitted from the concave mirror 106.

The spatial light phase converter 2 according to the present invention
00 is disposed immediately before the folding plane mirror 108, and the parallel light emitted from the folding plane mirror 108 is given a phase delay to each of the laser beams for each wavelength by the method described in the above embodiment. Is to give.

Thus, the short-wavelength component laser light of the incident femtosecond laser light is sequentially changed from d1 to e1, f1,.
In the path of g, the laser light of the long wavelength component of the incident femtosecond laser light travels in the order of e2, f2, and g from d2, and converges at the g on the diffraction grating 104 and emits the femtosecond laser light. Become.

By the way, of the femtosecond laser light,
The wavelength component intermediate between the short wavelength component and the long wavelength component described above is
Proceeding on an intermediate path of the above-described paths, the light is condensed at g on the diffraction grating 104 and becomes an output femtosecond laser light.

Here, in the diffraction grating 104, the incidence c of the incident femtosecond laser light and the emission g of the emitted femtosecond laser light are vertically displaced from each other at a small interval, and as a result, the incident femtosecond The emitted femtosecond laser light can be extracted spatially separated from the second laser light.

The beam splitter 110 reflects a part of the outgoing femtosecond laser light to form the autocorrelator 1.
The light is emitted to the reference numeral 12.

The autocorrelator 112 is the beam splitter 1
10 is for observing the pulse width of the outgoing femtosecond laser light that has entered. The output signal from the autocorrelator 112 as a result of the observation is analyzed using a personal computer, and the analyzed result is fed back to the wideband spatial light phase modulator 200 according to the present invention.

In the above configuration, the femtosecond laser light output from the femtosecond laser oscillator 100 is
The wavelength-dispersed laser light of each wavelength of the incident femtosecond laser light, which is wavelength-dispersed by the diffraction grating 104 via the 45-degree incident plane mirror 102, is transmitted through the concave mirror 106 and the folded plane mirror 108 to the broadband spatial light phase according to the present invention. The light enters the modulator 200.

Then, in the wide-band spatial light phase modulator 200 according to the present invention, the laser light of each wavelength of the wavelength-dispersed incident femtosecond laser light is incident on each of the quartz parallel plane plates 18 and the quartz Parallel plane plate 18
Is independently and arbitrarily changed to perform phase modulation.

In this case, for example, it is assumed that the incident femtosecond laser beam has a pulse width extended by transmitting and propagating through a substance, and the pulse width is compressed to return to the original non-extended state. It is also possible to increase the pulse width or change the phase plane.

In the present embodiment, the femtosecond laser oscillator 100, the diffraction grating 104, and the concave mirror 106 are used. However, the present invention is not limited to these, and the femtosecond oscillator / amplifier may be used instead of the femtosecond oscillator 100. The system may use a prism in place of the diffraction grating 104 and an achromatic lens in place of the concave mirror 106.

Next, a second application example using the wide-band spatial light phase modulator according to the present invention will be described with reference to FIG. This second application example corresponds to a case where the wide-band spatial light phase modulator 200 according to the present invention is used, for example, in processing a difficult-to-process material using an ablation action.

This second application example is configured to include a wide-band spatial light phase modulator 200 according to the present invention and a lens 114 such as a convex mirror.

The wide-band spatial light phase modulator 20 according to the present invention
The laser light incident on 0 is a high output pulse laser, and uses a harmonic of an excimer laser oscillating in the ultraviolet region or a solid laser oscillating in the visible region or near infrared region.

Broadband spatial light phase modulator 20 according to the present invention
0 is a phase difference of π with respect to a harmonic of an incident excimer laser or a solid-state laser oscillating in a visible region or a near-infrared region, that is, a half value, by independently and arbitrarily changing the inclination of the quartz parallel plate 18. This is to provide a wavelength phase difference.

The lens 114 such as a convex mirror focuses the transmitted laser light having a half-wave phase difference from the broadband spatial light phase modulator 200 according to the present invention on the surface of a solid material.

In the above configuration, the laser beam is given a half-wave phase difference by the wide-band spatial light phase modulator 200 according to the present invention, and is focused on the surface of the solid material by the lens 114 such as a convex mirror.

Thus, the periodic structure is finely processed on the surface of the solid material. Here, as the object to be processed, a difficult-to-process material such as quartz or a semiconductor element can be used.

Therefore, for example, a fiber grating, a holographic grating (holographic diffraction grating), a one-dimensional quantum well structure of a semiconductor, and the like can be formed.

[0099]

As described above, the present invention is constructed as described above, so that it can be used to generate short pulse laser light, or to extend while transmitting or propagating through a substance. When recompressing the pulse width of a short pulse laser beam, the dispersion compensation can be precisely controlled, and it can be used in a wide wavelength range, and regardless of the power of the laser beam. There is an excellent effect that a wideband spatial light phase modulator which can be used can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of an example of an embodiment of a broadband spatial light phase modulator according to the present invention, wherein (a) is a schematic front explanatory diagram, and (b) is a central portion of (a). It is a schematic side explanatory drawing of a part.

FIG. 2 is an explanatory diagram showing transmission wavelength ranges of various solid materials.

FIG. 3 is a schematic configuration explanatory view showing a first application example using a wideband spatial light phase modulator according to the present invention.

FIG. 4 is a view taken in the direction of the arrow C in FIG. 3;

FIG. 5 is a schematic structural explanatory view showing a second application example using the wideband spatial light phase modulator according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Support stand 12 Support column 14 Shaft 16 Bearing cylinder 17 Central support member 18 Quartz parallel plane plate 20 Bimorph piezo actuator 22 Lead wire 24 Controller 100 Femtom second laser oscillator 102 45 degree incidence plane mirror 104 Diffraction grating 106 Concave mirror 108 Folding Plane mirror 110 beam splitter 112 autocorrelator 114 lens 200 wide-band spatial light phase modulator

Claims (5)

[Claims] 1. A plurality of parallel flat plates made of an optically transmissive material, support means for aligning and supporting the parallel flat plates in a spatially movable state, and changing the inclination of the parallel flat plates A wide-band spatial light phase modulator having a tilt changing means. 2. The wide-band spatial light phase modulator according to claim 1, wherein the plane-parallel plate is made of quartz. 3. The wide-band spatial light phase modulator according to claim 1, wherein the inclination changing means applies an independent and arbitrary inclination to each of the parallel plane plates. A wide-band spatial light phase modulator that independently and arbitrarily tilts each of the parallel plane plates by the tilt changing means, thereby giving an independent and arbitrary phase change to laser light transmitted through each of the parallel plane plates. . 4. The wide-band spatial light phase modulator according to claim 1, further comprising wavelength dispersion means for wavelength-dispersing the laser light incident on the plane-parallel plate, When the laser light of each wavelength wavelength-dispersed by the wavelength dispersing means is incident on the plane-parallel plate, by giving an independent and arbitrary phase change to each wavelength component, the pulse width can be reduced. A wide-band spatial light phase modulator for compressing, expanding a pulse width, or controlling a pulse waveform. 5. The wide-band spatial light phase modulator according to claim 1, further comprising a condensing means for condensing the laser light transmitted through the parallel plane plate. A wide-band spatial light phase modulator for finely processing a periodic structure on the surface of the solid material by condensing the laser light transmitted through the parallel plane plate on the surface of the solid material by the light condensing means.