JP3460960B2 - Broadband spatial light phase modulator - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

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

That is, a short pulse laser light having a pulse width of about femtoseconds to picoseconds must have a wide spectrum width in inverse proportion to the pulse width, and the generation of the short pulse laser light is required. Requires a pulse compression technique for controlling the phase of each wavelength component in a wide spectrum.

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

Therefore, as described above, as a method of generating a short pulse laser beam by compressing a pulse having a wide spectrum but a pulse width that is not sufficiently compressed, it is possible to pass through a substance, Alternatively, various techniques have been proposed as a method for restoring the original pulse width by recompressing the pulse width of the short pulse laser light that has been distracted during propagation. It is known to use a prism pair made up of two prisms, a diffraction grating pair made up of two diffraction gratings, a chirped mirror, or a spatial light phase modulator using a liquid crystal.

Here, in a prism pair consisting of two prisms or a diffraction grating pair consisting of two diffraction gratings, dispersion compensation is performed using such a prism pair or a diffraction grating pair to obtain a short pulse laser light. It is intended to compress the extended pulse width of.

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

Further, when the pulse width of the short pulse laser light is compressed by using the prism pair, when the power intensity of the short pulse laser light increases, the short pulse laser light passes through the prism pair. In addition, there is a problem that the pulse width is extended again due to the self-phase modulation of the short pulse laser light.

Also, when the pulse width of the short pulse laser light is compressed 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 prism pair described above. There is a problem that only low-order dispersion in a limited range can be compensated.

Further, when the pulse width of the short pulse laser light is compressed by using the diffraction grating pair consisting of two diffraction gratings, the loss of the short pulse laser light 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 beam after the pulse width is compressed is greatly reduced.

A recently known technique for solving the above-mentioned problems of the prism pair and the diffraction grating pair is a dispersion compensating mirror called a chirp mirror.

However, when the pulse width of the short pulse laser light is compressed by using the chirp mirror, the wavelength range of the short pulse laser light is limited due to 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 within the limited range.

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

Further, when the pulse width of the short pulse laser light is compressed using the spatial light phase modulator using liquid crystal, it is limited to the range from the visible region to the near infrared region due to the optical properties of the liquid crystal. 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 wide spectrum but a pulse width which is not sufficiently compressed, it is transmitted or propagated through a substance. The pulse width of the short pulse laser light that has been stretched during
Wide band spatial light phase modulator using a well-known prism pair, diffraction grating pair, chirped mirror or liquid crystal used for compression in order to transmit a substance or to restore the original pulse width of the pulse before it propagates. However, all of them have various problems as described above.

That is, those problems are re-extension of the pulse width by self-phase modulation of the short pulse laser light in the prism pair, energy reduction of the short pulse laser light after pulse width compression in the diffraction grating pair, prism pair and For low-order dispersion compensation in a diffraction grating pair, limitation of usable wavelength range in a spatial light phase modulator using a chirp mirror and liquid crystal, limitation of usable laser light power in a spatial light phase modulator using liquid crystal, etc. there were.

That is, as a method of generating a short pulse laser beam by compressing a pulse having a wide spectrum but a pulse width which is not sufficiently compressed, it is transmitted or propagated through a substance. The pulse width of the short pulse laser light that has been stretched in between,
Various techniques have been proposed in the past as described above as a method of compressing in order to transmit the substance or to return to the original pulse width that has not been stretched before propagating, but it is possible to precisely control the dispersion compensation. There are problems that it is difficult, that it cannot be used in a wide wavelength range, and that it cannot be used regardless of the strength of the laser beam power.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the above-mentioned conventional techniques, and its object is to generate a short pulse laser beam. In addition, in the case of recompressing the pulse width of a short pulse laser light that has been elongated while transmitting or propagating in a substance, dispersion compensation can be precisely controlled and a wide range. An object of the present invention is to provide a wide band spatial light phase modulator that can be used in the wavelength range and can be used regardless of the strength of laser light.

[0019]

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 transparent material and the parallel plane plates are aligned and supported in a spatially movable state. And a tilt changing means for changing the tilt of the parallel plane plate.

Here, the above-mentioned "plurality of parallel plane plates made of an optically transparent material" corresponds to the "parallel plane plate 18" in the section of "Embodiment of the invention", and the above-mentioned "supporting means". Corresponds to the “support pillar 12”, the “shaft 14”, and the “bearing cylinder 16” in the “embodiment of the invention”, and the above “inclination changing means” in the “embodiment of the invention”. Corresponds to "Bimorph Piezo Actuator 20".

The invention according to claim 2 of the present invention is the invention according to claim 1 of the present invention, wherein the plane-parallel plate is made of quartz.

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

The invention according to claim 3 of the present invention is the invention according to claim 1 or 2 of the present invention, wherein the inclination changing means is each of the parallel plane plates. Independently and arbitrarily inclining each of the parallel plane plates by the inclination changing means independently and arbitrarily inclining each of the parallel plane plates to independently and arbitrarily phase the laser light passing through each of the parallel plane plates. It was designed to 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 is transmitted through each of the parallel plane plates. By giving an independent and arbitrary phase change to the light, spatial phase modulation is given to the light transmitted through the plurality of parallel plane plates.

The invention according to claim 4 of the present invention is the invention according to claim 1, 2 or 3 of the invention, further comprising a laser beam incident on the plane-parallel plate. It has a wavelength dispersion means for wavelength-dispersing light, and when the wavelength-dispersed laser light of each wavelength of the laser light incident by the wavelength dispersion means is incident on the plane-parallel plate, it is independent of each wavelength component. By applying an arbitrary phase change, the pulse width is compressed, the pulse width is extended, or the pulse waveform is controlled.

Therefore, according to the invention of claim 4 of the present invention, the laser light incident on the plane-parallel plate is dispersed into 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 the pulse width is extended, or , The pulse waveform is controlled.

According to a fifth aspect of the present invention, in the invention according to any one of the first, second or third aspects of the present invention, a laser beam transmitted through the parallel plane plate is further added. The light collecting means has a light collecting means, and the light collecting means collects the laser light transmitted through the plane-parallel plate on the surface of the solid material, thereby finely processing the periodic structure on the surface of the solid material. It was done like this.

Therefore, according to the invention described in claim 5 of the present invention, the laser light transmitted through the plane-parallel plate is condensed by the condensing means on the surface of the solid material, whereby the solid material The periodic structure will be finely processed on the surface.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of a wideband optical phase modulator according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic front explanatory view (see FIG. 1A) showing a schematic configuration of an example of an embodiment of a wide band spatial light phase modulator according to the present invention and a schematic side explanatory view of a central portion (FIG. 1). 1 (b)) is shown.

In FIG. 1, a wide band spatial light phase modulator 200 according to the present invention has two support columns 12 which are vertically and fixedly arranged on an upper surface of a support base 10. These two support columns are provided. A shaft 14 that connects the two is disposed at the upper end portion of the shaft 12, and five bearing cylinders 16 are rotatably supported by the shaft 14 so as to be rotatably supported by the shaft 14.・ Cylinder 16
Is made movable.

Further, quartz parallel plane plates 18 are attached to the five bearing cylinders 16, respectively. That is, in this embodiment, quartz is used as the optically transparent material.

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

A central support member 17 is attached between the two support columns 12 arranged on the support base 12. The central support member 17 is connected to the controller 24 via a lead wire 22. Five bimorph piezo actuators 20 that 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 is arranged.
The lower end of 8 and the upper end of each bimorph piezo actuator 20 are in contact with each other.

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

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

However, in this embodiment, a single quartz parallel plane plate 18 is attached to one bearing cylinder 16, and the bearing cylinder 16 is provided with such a quartz parallel plane plate 18. 5 are used.

Further, the bearing cylinders 16 provided with the quartz parallel flat plate 18 are each independently movable around the shaft 14 as a central axis.

Further, in this embodiment, the quartz parallel plane plate 18 attached to the bearing cylinder 16 is a 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 light transmission wavelength range of quartz is about 0.15 μm to 3.0 μm, and naturally, the light transmission wavelength range of the quartz parallel flat plate 18 is also 0.15 μm to 3.0 μm.
It becomes μm to 3.0 μm.

The quartz parallel flat plate 18 is attached to the bearing cylinder 16 and spatially arranged.

Further, as described above, the quartz parallel flat plate 18
5 bearing cylinders 16 each with
Are independently rotatable about the shaft 14 as the central axis, the quartz parallel flat plates 18 attached to the bearing cylinders 16 are also independent about the shaft 14 as the central axis. It can be freely rotated.

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

Bimorph Piezo Actuator 2
The lower end of 0 is attached to the central support member 17, and the upper end of each bimorph piezo actuator 20 is in contact with each quartz parallel flat plate 18.

The electrical control from the controller 24 is carried out by the bimorph piezo
When the bimorph piezo actuator 20 is transmitted to the actuator 20 and a voltage is applied, the bimorph piezo actuator 20 is distorted according to the magnitude of the applied voltage and is bent in the direction of arrow A in FIG.

Since the bimorph piezo actuator 20 is in contact with the quartz parallel flat plate 18 at its upper end, the bimorph piezo actuator 20 is
1 is applied with a voltage by the controller 24, the bimorph piezo actuator 20 is bent in the direction of arrow A in FIG. Will be inclined in the direction of.

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

A case in which short pulse laser light is incident on the above-described wide band spatial light phase modulator 200 will be described.

Here, a short pulse is applied to the quartz parallel flat 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 plane-parallel plate having a thickness d made of a certain optically transparent material will be described.

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

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

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

Therefore, as compared with the case where the light having the wavelength λ is perpendicularly incident on the parallel plane plate, the distance in which the light having the wavelength λ propagates in the parallel plane plate becomes longer, so that the phase change amount increases. It will be.

At this time, the relationship between the incident angle θ of the light having the wavelength λ on the plane-parallel plate and the phase change amount φ (θ) is φ (θ) = 2πd / λ · {(n ² −n ₀ ² sin ² θ) ^1/2 −n ₀ cos θ} (2)

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

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

Even when laser light is incident on the quartz parallel flat plate 18, by changing the inclination of the quartz parallel flat plate 18 based on the above-described principle.
The laser light passing through each quartz parallel plate 18 can be delayed by an arbitrary phase, and the spatial light phase modulation can be applied to the laser light passing over a plurality of parallel flat plates.

Here, when the short pulse laser light is incident on the quartz parallel flat 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 is bent in the direction of arrow A in FIG.

When the bimorph piezo actuator 20 bends in the direction of arrow A in FIG. 1 (b), the quartz parallel flat plate 18 tilts in the direction of arrow B in FIG. 1 (b).

At this time, the inclination of the quartz parallel flat plate 18 is
It can be changed independently and arbitrarily by electrical control from the controller 24 according to the incident laser light.

Assuming that the thickness d of the quartz parallel flat plate 18 and the wavelength λ of the laser light are the refractive index n of the quartz parallel flat plate 18 and the refractive index n _{0 of} air at the wavelength λ, the quartz parallel flat plate 18 is shown. The phase delay φ when the short pulse laser light is vertically incident on is calculated by the equation (1).

Further, the quartz parallel plane plate 18 is provided with a bimorph.
By giving an arbitrary inclination by the piezo actuator 20, the laser light is incident on the quartz parallel flat plate 18 at the incident angle θ, and the relationship between the incident angle θ and the phase delay φ (θ) at that time. It is obtained by the equation (2).

By changing the inclination of the quartz parallel flat plate 18 independently and arbitrarily with respect to such a phase delay, it becomes possible to apply phase modulation to the laser light incident on the quartz parallel flat plate 18.

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

When laser light of different wavelengths is made incident on each of the five quartz parallel plane plates 18 by using a dispersive element such as a prism or a diffraction grating, a phase delay different for each wavelength is provided. That is, it becomes possible to give a phase change.

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

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

Further, the pulse width of the stretched laser light within the above wavelength range and the power intensity range of the laser light is compressed in order to return to the original pulse width which has not been stretched before transmitting and propagating through the substance. can do.

Although five quartz parallel plane plates 18 are used in the above embodiment, the number of quartz parallel plane plates 18 is not limited to this, and any number of quartz parallel plane plates 18 may be used. Good.

Further, in the above-mentioned embodiment, the quartz parallel plane plate 18 made of quartz is used, but the parallel plane plate may be made of an optically transparent material, for example, shown in FIG. Various solid materials having such a transmission wavelength range may be used as the optically transparent material.

Further, in the above-mentioned embodiment, the bimorph piezo actuator 20 is used to change the inclination of the quartz parallel plate 18, but the present invention is not limited to this, and other means may be used. May be.

Next, referring to FIGS. 3 and 4,
A first application example using the broadband spatial light phase modulator according to the present invention will be described. In this first application example, the broadband spatial light phase modulator according to the present invention is used, for example, to increase the intensity of a pumping laser required to generate soft X-ray coherent light, which is a light source of an X-ray microscope, and to shorten it. This corresponds to the case of using it when making it into a pulse.

FIG. 3 is a schematic structural explanatory view of the above-mentioned first application example, 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, and 45
Of the incident plane mirror 102, the diffraction grating 104 for wavelength-dispersing the femtosecond laser light and extracting the emitted femtosecond laser light, the concave mirror 106 arranged with the focal length of the concave mirror 106 from the diffraction grating 104, and the concave mirror to the concave mirror 106. Folded plane mirror 1 arranged with a focal length
08, and the broadband spatial light phase modulator 200 according to the present invention disposed between the concave mirror 106 and the folding plane mirror 108.
, A beam splitter 110, and an autocorrelation meter 112.

The femtosecond laser oscillator 100 outputs femtosecond laser light as short pulse laser light, and the femtosecond laser light output is 45.
The diffraction grating 10 at an appropriate angle through the incident plane mirror 102.
4 (herein, the diffraction grating 104
The femtosecond laser light incident on is referred to as "incident femtosecond laser light" as appropriate).

The diffraction grating 104 wavelength-disperses the incident femtosecond laser light, and separates it according to each wavelength and diffracts it in different directions. At that time, the laser light of the short wavelength component of the incident femtosecond laser light is incident on the concave mirror 106 through the path of c to d1, and the laser light of the long wavelength component of the incident femtosecond laser light is incident on the concave mirror 106 through the path from c to d2. It

The concave mirror 106 is one on which each of the laser beams of different wavelengths dispersed by the diffraction grating 104 enters. Here, by arranging the concave mirror 106 and the diffraction grating 104 so that the distance between them is 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 plane mirror 108 for folding is a concave mirror 106.
The parallel light emitted from the concave mirror 106 is turned back by arranging so that the distance between and is equal to the focal length of the concave mirror 106.

Then, the spatial light phase converter 2 according to the present invention
00 is arranged immediately before the plane mirror for folding 108, and the parallel light emitted from the plane mirror for folding 108 is delayed in phase with each of the laser beams for each wavelength by the method as described in the above embodiment. To give.

Thus, the laser light of the short wavelength component of the incident femtosecond laser light is 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 is collected and emitted as femtosecond laser light at g on the diffraction grating 104. Become.

By the way, of the femtosecond laser light,
The wavelength component between the short wavelength component and the long wavelength component described above is
The light travels in the middle of the above-mentioned paths and is condensed at g on the diffraction grating 104 to be emitted femtosecond laser light.

Here, in the diffraction grating 104, the incident c of the incoming femtosecond laser light and the outgoing g of the outgoing femtosecond laser light are vertically displaced at a slight interval, whereby the incident femtosecond laser light is shifted. The emitted femtosecond laser light can be extracted by spatially separating from the second laser light.

Then, the beam splitter 110 reflects a part of the emitted femtosecond laser light to reflect the autocorrelation 1
It is emitted to 12.

The autocorrelator 112 is the beam splitter 1
The pulse width of the emitted femtosecond laser light incident by 10 is observed. The output signal from the autocorrelator 112, which is the result of the observation, is analyzed using a personal computer, and the analyzed result is fed back to the wide band 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 wavelength-dispersed by the diffraction grating 104 via the 45-degree incident plane mirror 102 is passed through the concave mirror 106 and the folding plane mirror 108 to obtain the broadband spatial optical phase according to the present invention. The light enters the modulator 200.

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 made incident on each of the quartz parallel flat plates 18, and the quartz quartz Plane-parallel plate 18
Phase modulation is performed by independently and arbitrarily changing the slope of.

Here, for example, assuming that the incident femtosecond laser beam has a pulse width extended by being transmitted and propagated in the substance, the pulse width is compressed to restore the original non-extended state. It is also possible to increase the pulse width or change the phase plane.

Although the femtosecond laser oscillator 100, the diffraction grating 104, and the concave mirror 106 are used in this embodiment, the femtosecond oscillator / amplifier can be used instead of the femtosecond oscillator 100. The system may use prisms in place of diffraction grating 104 and achromatic lenses in place of 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 is applicable to the case where the broadband spatial light phase modulator 200 according to the present invention is used, for example, in the processing of a difficult-to-process material using an ablation action.

The second application example is constructed by including the wide band spatial light phase modulator 200 according to the present invention and the lens 114 such as a convex mirror.

Broadband spatial light phase modulator 20 according to the present invention
The laser light incident on 0 is a high-power pulse laser, and uses a harmonic of an excimer laser that oscillates in the ultraviolet region or a solid-state laser that oscillates in the visible / near-infrared region.

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

The lens 114 such as a convex mirror collects the transmitted laser light from the broadband spatial light phase modulator 200 according to the present invention, which is given a phase difference of half wavelength, on the surface of the solid material.

In the above structure, the laser light is given a half-wavelength phase difference by the broadband spatial light phase modulator 200 according to the present invention, and is condensed 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, it is possible to use quartz or a difficult-to-process substance such as a semiconductor element.

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

[0099]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, when the short pulse laser light is generated, it is extended while being transmitted or propagated through the substance. When re-compressing the pulse width of a short pulsed laser light, the dispersion compensation can be precisely controlled and can be used in a wide wavelength range, and regardless of the power of the laser light. The excellent effect of being able to provide a wideband spatial light phase modulator that can be used is exhibited.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of an example of an embodiment of a wide band spatial light phase modulator according to the present invention, in which (a) is a schematic front explanatory view and (b) is a center of (a). It is a schematic side surface 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 the wide band spatial light phase modulator according to the present invention.

FIG. 4 is a view on arrow C in FIG.

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

[Explanation 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 Incident Plane Mirror 104 Diffraction Grating 106 Concave Mirror 108 For Folding Plane mirror 110 Beam splitter 112 Autocorrelator 114 Lens 200 Wideband spatial light phase modulator

Claims (5)

(57) [Claims] 1. A plurality of parallel plane plates made of an optically transparent material, a support means for aligning and supporting the parallel plane plates in a spatially movable state, and changing the inclination of the parallel plane plates. Wideband spatial optical phase modulator having tilt changing means. 2. The broadband spatial light phase modulator according to claim 1, wherein the parallel plane plate is made of quartz. 3. The broadband spatial light phase modulator according to claim 1, wherein the tilt changing means gives each of the parallel plane plates an independent and arbitrary tilt. A wide-band spatial light phase modulator that independently and arbitrarily tilts each of the parallel plane plates by the tilt changing means to independently and arbitrarily change the phase of the laser light that passes through each of the parallel plane plates. . 4. The broadband 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 wavelength-dispersed laser light of the respective wavelengths of the laser light incident by the wavelength dispersion means is incident on the parallel plane plate, each wavelength component is given an independent and arbitrary phase change, so that the pulse width A broadband spatial light phase modulator that performs compression, pulse width extension, or pulse waveform control. 5. The broadband spatial light phase modulator according to claim 1, further comprising a condensing unit that condenses the laser light that has passed through the plane-parallel plate. A broadband spatial light phase modulator for finely processing a periodic structure on the surface of a solid material by condensing laser light transmitted through the plane-parallel plate by the light collecting means on the surface of the solid material.