JPH10239721A - High-speed wavelength converting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rotates nonlinear optical crystal fast to an arbitrary position, by providing a rotating means, which rotates the nonlinear optical crystal fast. SOLUTION: The nonlinear optical crystal 10 generates a secondary higher harmonic of frequency 2ω by converting inputted exciting laser light of frequency ω. The nonlinear optical crystal 10 is freely rotated by a galvanometer scanner 24 on an axis of rotation so that the angle of incident of the exciting laser light of frequency ω to the crystal axis can be matched with a phase matching angle. Total reflecting mirrors 14 and 16 are also rotated by the galvanometer scanner 24. A beam position detector 22 always monitors the beam position of laser light reflected by the total reflecting mirror 16 and according to the monitoring result, the angle of rotation of the nonlinear optical crystal 10 and the rotational positions of the total reflecting mirrors 14 and 16 are corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed wavelength converter, and more particularly, to a high-speed wavelength converter for laser light using a nonlinear optical crystal, and more particularly to a wavelength of laser light incident on the nonlinear optical crystal. In response to the change, whatever the wavelength of the incident laser light,
The present invention relates to a high-speed wavelength conversion device capable of efficiently performing wavelength conversion satisfying a phase matching condition in a desired nonlinear optical crystal and effectively separating and extracting the wavelength.

[0002]

2. Description of the Related Art In recent years, 7 × 1
It has become possible to speed up the wavelength sweep, for example, to achieve 0 ⁵ nm / sec, and to selectively emit laser light of a desired wide range of wavelengths.

[0003] The variable wavelength range of a titanium sapphire laser using such an electronically controlled laser wavelength variable technique is 700 nm-1100, even though it is wide.
nm.

[0004] Therefore, in order to use such a titanium sapphire laser in the ultraviolet region, which is in great demand as a light source, 7
It was necessary to perform wavelength conversion by converting a laser beam of 00 nm to 1100 nm into a higher harmonic wave. Incidentally, the wavelength of the second harmonic of light having a wavelength of 700 nm-1100 nm is 350 nm-550 nm, the wavelength of the third harmonic is 235 nm-370 nm, and the wavelength of the fourth harmonic is 175 nm-275 nm. , 70
By converting the laser light of 0 nm-1100 nm into harmonics, the wavelength range from 200 nm, which is the short wavelength limit, which is limited by the absorption of the nonlinear optical crystal itself, to the wavelength range of 550 nm, which is the long wavelength limit of the second harmonic, is obtained.
It has been pointed out that a tunable light source can be constructed based on a titanium sapphire laser.

On the other hand, as a wavelength conversion technique of laser light using harmonic conversion, for example, a laser light having a frequency ω is incident as excitation laser light into a nonlinear optical crystal to perform harmonic conversion of the excitation laser light. There is known a nonlinear wavelength conversion method in which a laser beam containing a second harmonic (frequency 2ω) of an excitation laser beam is emitted as a converted laser beam from a nonlinear optical crystal.

Here, in the nonlinear wavelength conversion method using a nonlinear optical crystal, all components of the pump laser light are 2
Instead of being converted to the second harmonic component, the converted laser light emitted from the nonlinear optical crystal includes a component of the frequency ω of the pump laser light and a component of the frequency 2ω of the second harmonic of the pump laser light. include.

In this specification, laser light incident on the nonlinear optical crystal is referred to as “excitation laser light”, and laser light emitted from the nonlinear optical crystal is referred to as “converted laser light”.

In such a nonlinear wavelength conversion method, it is necessary to satisfy a phase matching condition between the pump laser light and the nonlinear optical crystal.

As a method for satisfying the phase matching condition, the direction of the crystal axis of the nonlinear optical crystal is changed by rotating the nonlinear optical crystal with respect to the excitation laser beam, and the pumping of the nonlinear optical crystal with respect to the crystal axis is performed. There is known a method of adjusting an incident angle of a laser beam to a phase matching angle satisfying a phase matching condition.

Here, the above-mentioned phase matching condition is such that the required wavelength of the converted laser light emitted from the nonlinear optical crystal and the excitation laser light incident on the nonlinear optical crystal required for the required wavelength of the converted laser light. Is determined uniquely when given the wavelength. Therefore, when trying to change the wavelength of the converted laser light emitted from the nonlinear optical crystal, it is necessary to change the wavelength of the excitation laser light incident on the nonlinear optical crystal every time the wavelength of the converted laser light is changed. At the same time, it is necessary to adjust the angle of incidence of the excitation laser beam with respect to the crystal axis to the phase matching angle by rotating the nonlinear optical crystal, but conventionally, as a wavelength conversion device using the nonlinear wavelength conversion method, 2. Description of the Related Art A wavelength converter having a configuration in which a nonlinear optical crystal is rotated manually or by a motor according to a change in wavelength is known.

That is, FIG. 1 shows a conventional wavelength converter for obtaining the second harmonic of the pump laser light.
For example, the nonlinear optical crystal is rotated around a rotation axis positioned on the crystal axis by using a stepping motor, and the incident angle of the excitation laser light having the frequency ω with respect to the crystal axis is adjusted to the phase matching angle.

In order to separate a component of frequency ω and a component of frequency 2ω from the converted laser light emitted from the nonlinear optical crystal, for example, a dichroic mirror is arranged on the optical path of the converted laser light, For example, the component of the frequency ω of the converted laser light is transmitted through the dichroic mirror, and the component of the frequency 2ω of the converted laser light is reflected by the dichroic mirror, and the component of the frequency 2ω of the converted laser light is used. Have to be able to.

However, in the conventional wavelength converter described above, for example, the nonlinear optical crystal is rotated by using a stepping motor. However, since the stepping motor has a large moment of inertia, it is necessary to rotate and stop at high speed. There is a problem that the nonlinear optical crystal cannot be repeatedly rotated to an arbitrary position.

For this reason, in the conventional wavelength converter, the nonlinear optical crystal cannot be rotated by following the high-speed tunable speed of the titanium sapphire laser using the electronically controlled laser tunable technology.
It has not been possible to realize a light source capable of changing the wavelength at high speed over a wavelength range from 0 nm to 550 nm.

In the conventional wavelength converter, each wavelength component of the converted laser light composed of a plurality of wavelength components is separated using, for example, a dichroic mirror. Since the directions of the beams are different and the optical axes do not coincide with each other, there is a problem that it is extremely inconvenient in practical use when using each wavelength component.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned various problems of the prior art, and an object of the present invention is to provide a non-linear optical crystal at a high speed and at an arbitrary speed. It is an object of the present invention to provide a high-speed wavelength converter capable of rotating to a position.

Another object of the present invention is to provide a high-speed wavelength conversion device in which the directions of the beams of the respective wavelength components separated from the converted laser light emitted from the nonlinear optical crystal are made constant so that the optical axes coincide with each other. Is what you do.

[0018]

In order to achieve the above object, according to the first aspect of the present invention, a laser beam is incident on a non-linear optical crystal rotatably supported, and a harmonic conversion is performed. In a high-speed wavelength conversion device that performs wavelength conversion of the laser light, a rotation unit that rotates the nonlinear optical crystal at a high speed, and a separation unit that separates a desired harmonic component from the laser light emitted from the nonlinear optical crystal. ,
A desired harmonic component separated by the separation means,
And arranging means for arranging them on a predetermined optical path.

Therefore, according to the first aspect of the present invention,
It is possible to rotate the nonlinear optical crystal to an arbitrary position at a high speed by the rotation means, and to arrange the desired harmonic component separated by the separation means on a predetermined optical path by the arrangement means. The optical axes can be matched by keeping the direction of the beam of the higher harmonic component constant.

Here, the invention according to claim 2 of the present invention is characterized in that the rotating means is arranged such that an incident angle of the laser beam with respect to a crystal axis of the nonlinear optical crystal becomes a phase matching angle.
The above-described nonlinear optical crystal is rotated at a high speed.

In the invention according to claim 3 of the present invention, the rotating means is a galvanometer scanner.

In the invention according to a fourth aspect of the present invention, the separating means is a prism.

According to a fifth aspect of the present invention, a plurality of the nonlinear optical crystals are arranged on the same optical axis, and the rotating means selectively rotates the plurality of the nonlinear optical crystals. The incident angle of the laser beam with respect to the crystal axes of the plurality of nonlinear optical crystals is selectively set to a phase matching angle.

In the invention according to a sixth aspect of the present invention, the arranging means is a mirror variably arranged so that an optical path can be reflected in an arbitrary direction, and a movable means for moving the mirror at high speed is provided. It is intended to have.

Here, in the invention according to claim 7 of the present invention, the movable means is a galvanometer scanner.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a high-speed wavelength converter according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 2 is a conceptual diagram showing an example of an embodiment of a high-speed wavelength converter according to the present invention. The high-speed wavelength converter includes a pump laser beam incident on the high-speed wavelength converter. A laser beam having a frequency of ω such as a titanium sapphire laser is used as a laser beam.
Is provided with the nonlinear optical crystal 10 that generates the second harmonic of the above.

Further, at the subsequent stage of the nonlinear optical crystal 10, a converted laser light having a frequency ω component and a frequency 2ω component emitted from the nonlinear optical crystal 10 is incident, and the converted laser light having the frequency ω Component and frequency 2ω
And a total reflection mirror that reflects the frequency ω component and the frequency 2ω component that are refracted and dispersed in the optical path corresponding to the respective frequencies and emitted. 14, 16, an aperture plate 18 having an opening 18 a in the center, a beam splitter 20, and a beam position detector 22 are sequentially arranged.

Then, the user uses the laser light that has passed through the aperture 18a of the aperture plate 18 and passed through the beam splitter 20.

FIG. 2 shows a state where the component of the frequency 2ω is used by the user.

Here, the nonlinear optical crystal 10 is rotatable about a rotation axis so that the incident angle of the excitation laser light having the frequency ω with respect to the crystal axis can be adjusted to the phase matching angle. As a configuration for rotating the nonlinear optical crystal 10, a galvanometer scanner 24 that is linked to a change in the wavelength of the incident excitation laser light is used.

FIG. 3A is a schematic plan view of a main part showing a state in which the nonlinear optical crystal 10 is attached to the galvanometer scanner 24, and FIG. 3B is a view in which the nonlinear optical crystal 10 is attached to the galvanometer scanner 24. FIG. 3 is a side view of a schematic configuration of a main part (showing a state in which the galvanometer scanner 24 is attached to a gantry) showing a state in which the galvanometer scanner 24 is attached via a holder to a gantry installed on a table. The nonlinear optical crystal 10 is attached to the rotation axis. The galvanometer scanner 24 has a small moment of inertia, and is required to rotate the nonlinear optical crystal 10 by 1 °.
It takes only about 1 msec from start to stop. Therefore, by rotating the nonlinear optical crystal 10 by the galvanometer scanner 24, for example,
Even when the incident angle of the excitation laser light having the frequency ω with respect to the crystal axis of the nonlinear optical crystal 10 is to be changed by 20 °,
It takes only a very short time of about 20 msec.

Further, the total reflection mirrors 14 and 16 are configured to rotate at high speed about a rotation axis according to the wavelength of the laser beam to be used by the user.

In this embodiment, the total reflection mirrors 14 and 16 are also rotated by the galvanometer scanner 24.

As described above, the total reflection mirrors 1 and 16 are rotated about the rotation axis in accordance with the wavelength of the laser beam to be used by the user, so that the total reflection mirror 1 is rotated.
The optical axis of the laser beam reflected by the laser beam 6 can be kept constant at all times.
The convenience of the user using the laser light that has passed through the beam splitter 20 after passing through the beam splitter 8a is significantly improved.

The beam position detector 22 constantly monitors the beam position of the laser light reflected by the total reflection mirror 16, and based on the result, the rotation angle of the nonlinear optical crystal 10 and the total reflection mirror 14, By correcting the rotation position of the laser beam 16, the optical axis of the laser beam reflected by the total reflection mirror 16 can be more accurately maintained at a constant level.

To use this high-speed wavelength converter in the above configuration, first, the aperture 18a of the aperture plate 18 is used.
, Which passes through the beam splitter 20, ie, the wavelength λ of the laser light that the user wants to use.
_SHG is determined by the user.

Next, the wavelength λ _F of the excitation laser light incident on the nonlinear optical crystal 10 is obtained based on the wavelength λ _{SHG of the} laser light desired by the user.

[0039] Further, in correspondence to the wavelength lambda _F of the excitation laser light, the wavelength lambda _F with respect to the crystal axes of the nonlinear optical crystal 10
The nonlinear optical crystal 1 by the galvanometer scanner 24 so that the incident angle of the excitation laser light of
And the total reflection mirrors 14 and 16 are rotated so that only the laser beam of the wavelength λ _SHG reflected by the total reflection mirror 16 is positioned on the optical axis passing through the opening 18 a of the aperture plate 18. I do.

As described above, according to the wavelength λ _{SHG of the} laser beam desired by the user, the nonlinear optical crystal 10
Together with rotated by the galvanometer scanner 24, the total reflection mirror 14 rotates, after the positioning of the nonlinear optical crystal 10 and the total reflection mirror 14, the excitation wavelength lambda _F to the nonlinear optical crystal 10 Laser light enters.

When the excitation laser light having the wavelength λ _F is incident on the nonlinear optical crystal 10, the excitation laser light having the wavelength λ _F is converted into a harmonic by the nonlinear optical crystal 10, and the wavelength λ _SHG
The components and the wavelength lambda _F components and become more converted laser beam is emitted.

The converted laser light composed of the wavelength λ _SHG component and the wavelength λ _F component emitted from the nonlinear optical crystal 10 is incident on the prism 12, and the wavelength λ _SHG component and the wavelength λ _SHG are dispersed by the prism 12. The component of λ _F is refracted and dispersed in an optical path corresponding to each wavelength and emitted.

Further, the wavelength λ _SHG component and the wavelength λ _F component emitted from the prism 12 by dividing the optical path are reflected by the total reflection mirrors 14 and 16, and only the wavelength λ _SHG component is It passes through the opening 18a. The wavelength λ that has passed through the aperture 18a of the aperture plate 18
_{The SHG} component is split into two optical paths by a beam splitter 20, one of the splits is subjected to beam position detection by a beam position detector 22, and the other is used by a user.

Here, as described above, the aperture plate 1
The beam position detector 22 detects the beam position of one of the components of the wavelength λ _SHG that has passed through the aperture 18a of FIG. 8 and is divided by the beam splitter 20. It is used for correcting the positions of the reflection mirrors 14 and 16.

In this way, the detection result of the beam position detector 22 is determined by the nonlinear optical crystal 10 and the total reflection mirrors 14 and 16.
Is used for the correction of the position, the optical axis of the beam of the component of the wavelength λ _SHG reflected by the total reflection mirror 16 can be maintained more accurately and constant.

The above-described nonlinear optical crystal 10
In addition, it is preferable that the control of the positions of the total reflection mirrors 14 and 16 be systematized using a computer to perform the processing.

FIG. 4 is a conceptual block diagram of another embodiment of the high-speed wavelength converter according to the present invention, and FIG. 5 is a schematic view of the high-speed wavelength converter shown in FIG. A schematic actual arrangement diagram is shown. Note that the same or corresponding components as those in FIG. 2 are denoted by the same reference numerals as those used in FIG. 2, and detailed description of the configuration and operation is omitted.

The high-speed wavelength converter shown in FIG.
The high-speed wavelength converter shown in FIG. 1 generates only the second harmonic, whereas the second wavelength, the third harmonic, and the fourth harmonic can be appropriately generated. 2 is different from the high-speed wavelength converter shown in FIG.

That is, the high-speed wavelength converter shown in FIGS. 4 and 5 has a frequency ω of a titanium sapphire laser or the like as an excitation laser beam incident on the high-speed wavelength converter.
And a non-linear optical crystal 10 that performs harmonic conversion of the incident excitation laser light of frequency ω to generate a second harmonic of frequency 2ω.

Further, downstream of the nonlinear optical crystal 10, a correcting device 30 into which a converted laser beam having a frequency ω component and a frequency 2ω component emitted from the nonlinear optical crystal 10 is incident, and a correcting device 30 Rotator 32 that separates the laser light emitted from the laser into a component of frequency ω and a component of frequency 2ω to change the polarization direction, and a laser beam composed of a component of frequency ω and a component of frequency 2ω emitted from rotator 32 Is applied as the excitation laser light, and harmonic conversion is performed by the component of the frequency ω and the component of the frequency 2ω of the incident excitation laser light, and the frequency 3
A nonlinear optical crystal 34 that generates a third harmonic of ω, and a converted laser beam having a frequency ω component, a frequency 2ω component, and a frequency 3ω component emitted from the nonlinear optical crystal 34 are incident as excitation laser light. By performing harmonic conversion of the component of the frequency 2ω in the incident pump laser light,
Nonlinear optical crystal 36 for generating a fourth harmonic having a frequency of 4ω
And a converted laser beam having a frequency ω component, a frequency 2ω component, a frequency 3ω component, and a frequency 4ω component emitted from the nonlinear optical crystal 36 is incident, and the frequency ω component of the converted laser light and the frequency 2ω Component and frequency 3ω
And a component having a frequency of 4ω are refracted into an optical path corresponding to the respective wavelengths to be refracted, dispersed, and emitted. A component of the frequency ω, a component of the frequency 2ω, and a frequency of 3ω are emitted from the prism 12 by dividing the optical path. , And a total reflection mirror 14 and 16 for reflecting the component of the frequency 4ω, an aperture plate 18 having an opening 18a in the center, a beam splitter 20, and a beam position detector 22 are sequentially arranged. .

Then, the user uses the laser light that has passed through the aperture 18a of the aperture plate 18 and transmitted through the beam splitter 20.

Here, the nonlinear optical crystals 10, 34, 36
Are rotatable about a rotation axis so that an incident angle of a laser beam with respect to each crystal axis can be adjusted to a phase matching angle. Nonlinear optical crystal 10, 3
As a configuration for rotating the laser beams 4 and 36, a galvanometer scanner 24 that is linked to a change in the wavelength of the incident laser light is used.

The correcting device 30 is also provided with the nonlinear optical crystal 1.
It is rotatable about a rotation axis so that the incident angle of the excitation laser light emitted from 0 can be adjusted to the optimum angle. As a configuration for rotating the nonlinear optical crystal 30, a galvanometer scanner 24 that is linked to a change in the wavelength of the incident excitation laser light is used as in the case of the nonlinear optical crystals 10, 34, and 36.

The galvanometer scanner 24 for rotating the nonlinear optical crystals 10, 34 and 36 and the correcting device 30 is provided with an optical path between the nonlinear optical crystal 10 and the correcting device 30 and a path between the nonlinear optical crystal 34 and the nonlinear optical crystal 36. In order to shorten the optical path therebetween as much as possible, they are arranged so as to be staggered with respect to the optical path so as not to interfere with each other.

The total reflection mirrors 14 and 16 are configured to rotate at high speed about a rotation axis according to the wavelength of the laser light to be used by the user.

In this embodiment, the total reflection mirrors 14 and 16 are also rotated by the galvanometer scanner 24.

As described above, the total reflection mirrors 14 and 16 are rotated around the rotation axis in accordance with the wavelength of the laser beam to be used by the user, so that the total reflection mirror 1 is rotated.
The optical axis of the laser beam reflected by the laser beam 6 can be kept constant at all times.
The convenience of the user using the laser light that has passed through the beam splitter 20 after passing through the beam splitter 8a is significantly improved.

The beam position detector 22 constantly monitors the beam position of the laser beam reflected by the total reflection mirror 16, and based on the result, the rotation angles of the nonlinear optical crystals 10, 34 and 36 and the total angle. Reflection mirror 14, 1
By correcting the rotation position of the laser beam 6, the optical axis of the laser beam reflected by the total reflection mirror 16 can be maintained more accurately and constantly.

To use this high-speed wavelength converter in the above configuration, first, the aperture 18a of the aperture plate 18 is used.
The user determines the wavelength λ of the laser beam that passes through the beam splitter 20, that is, the laser beam that the user wants to use.

Next, whether to generate the second harmonic, the third harmonic, or the fourth harmonic based on the wavelength λ of the laser light that the user wants to use. determined in accordance with the order of the harmonics and the wavelength lambda for generating, determining the wavelength lambda _F of the excitation laser light incident to the nonlinear optical crystal 10.

Further, in accordance with the wavelength λ _F of the excitation laser beam and the order of the generated harmonic, the galvanometer scanner 24 uses the nonlinear optical crystals 10, 34,
And the total reflection mirrors 14 and 16 are rotated such that only the laser beam of wavelength λ _SHG reflected by the total reflection mirror 16 is positioned on the optical axis passing through the opening 18 a of the aperture plate 18. I do.

That is, when it is desired to generate the second harmonic, the nonlinear optical crystal 10 is rotated by the galvanometer scanner 24 so that the incident angle of the laser beam with respect to the crystal axis of the nonlinear optical crystal 10 becomes the phase matching angle. But,
Since there is no need to perform harmonic conversion on the nonlinear optical crystals 34 and 36, the galvanometer scanner 24 controls the nonlinear optical crystals 34 so that the incident angle of the laser beam with respect to the crystal axes of the nonlinear optical crystals 34 and 36 does not become the phase matching angle. , 36 are rotated.

When it is desired to generate the third harmonic, the galvanometer scanner 24 uses the galvanometer scanner 24 so that the incident angle of the laser beam with respect to the crystal axes of the nonlinear optical crystals 10 and 34 becomes the phase matching angle. Although the rotation of the nonlinear optical crystal 36 is not necessary, the galvanometer scanner 24 rotates the nonlinear optical crystal 36 so that the incident angle of the laser beam with respect to the crystal axis of the nonlinear optical crystal 36 does not become the phase matching angle. The crystal 36 is rotated.

Further, when it is desired to generate the fourth harmonic, the galvanometer scanner 24 uses the galvanometer scanner 24 so that the incident angle of the laser beam with respect to the crystal axis of the nonlinear optical crystals 10 and 36 becomes the phase matching angle. Although it is not necessary to perform harmonic conversion on the nonlinear optical crystal 34, the galvanometer scanner 24 controls the nonlinear optical crystal 34 so that the incident angle of the laser beam with respect to the crystal axis of the nonlinear optical crystal 34 does not become the phase matching angle. The crystal 34 is rotated.

That is, when the second harmonic of the pump laser light having the wavelength λ _F is required, the nonlinear optical crystals 34 and 36 are arranged so as not to perform the harmonic conversion, and the pump laser light having the wavelength λ _F is provided. When the third harmonic is required, the nonlinear optical crystal 36 is arranged so as not to perform the action of harmonic conversion,
When the fourth harmonic of the pump laser light having the wavelength λ _F is required, the nonlinear optical crystal 34 is arranged so as not to perform the harmonic conversion.

At this time, by rotating the non-linear optical crystals 10 and 36 facing each other, one of them can function as a correction device.

As described above, according to the wavelength λ _{SHG of the} laser beam desired by the user, the nonlinear optical crystal 1
0, 34, and 36 are rotated by the galvanometer scanner 24, and the total reflection mirrors 14 and 16 are rotated, so that the nonlinear optical crystals 10, 34 and 36 and the total reflection mirror 1 are rotated.
After the positioning with the nonlinear optical crystal 10
A laser beam having a wavelength λ _F is incident on the substrate.

When the excitation laser beam having the wavelength λ _F is incident on the nonlinear optical crystal 10, the same operation as described above with respect to the high-speed wavelength converter shown in FIG. 2 is performed via the nonlinear optical crystals 10, 34, 36. The components of the wavelength λ _SHG and the other wavelength components are refracted by the dispersion action of the prism 12 into optical paths corresponding to the respective wavelengths, dispersed and emitted.

Further, the component of the wavelength λ _SHG emitted from the prism 12 by dividing the optical path and the other wavelength components are reflected by the total reflection mirrors 14 and 16, and the wavelength λ _SHG
Only the _SHG component passes through the aperture 18a of the aperture plate 18. The component of the wavelength λ _SHG that has passed through the aperture 18 a of the aperture plate 18 is divided by the beam splitter 20 into two components.
One of the divided light paths is subjected to beam position detection by a beam position detector 22, and the other of the divided light paths is provided to a user.

Here, as described above, the aperture plate 1
The beam position detector 22 detects the beam position of one of the components of the wavelength λ _SHG that has passed through the aperture 18 a and is split by the beam splitter 20. The detection result is based on the nonlinear optical crystals 10 and 34. , 36 and the positions of the total reflection mirrors 14 and 16 are used for correction.

The detection result of the beam position detector 22 is used for correcting the positions of the nonlinear optical crystals 10, 34, 36 and the total reflection mirrors 14, 16, so that the wavelength λ reflected by the total reflection mirror 16 is used. The optical axis of the beam of the _SHG component can be more accurately kept constant.

The nonlinear optical crystal 1 as described above
It is preferable that the control of the positions of the mirrors 0, 34, 36 and the total reflection mirrors 14, 16 be systematized using a computer to perform the processing.

In the high-speed wavelength converter shown in FIGS. 4 and 5, in order to generate a component having a frequency of 3ω (the third harmonic of the pump laser beam), the component of the frequency ω (the pump laser beam) and the frequency The component of 2ω (the second harmonic of the pump laser light) is incident on the nonlinear optical crystal 34, and at this time, the rotator 32 rotates the polarization direction of the component of the frequency 2ω (the second harmonic of the pump laser light). Is rotated, and the component of the frequency ω (excitation laser light) and the frequency 2
The component of ω (the second harmonic of the pump laser light) is incident on the nonlinear optical crystal 34 such that the polarization directions of the components coincide with each other.

In this manner, the polarization direction of the component of the frequency ω (excitation laser beam) and the polarization direction of the component of the frequency 2ω (second harmonic of the excitation laser beam) are made to coincide with each other so that the component of the frequency 3ω (3 When the light enters the nonlinear optical crystal 34 for generating the second harmonic, the conversion efficiency of the harmonic conversion can be significantly improved.

However, the nonlinear optical crystal 10 that generates a component having a frequency of 2ω (second harmonic of the pump laser light)
The component of the frequency ω (excitation laser light) and the component of the frequency 2ω (the second harmonic of the excitation laser light)
Since the polarization directions are orthogonal to each other and are emitted from the nonlinear optical crystal 10, the polarization direction of the component of the frequency ω (excitation laser light) and the polarization direction of the component of the frequency 2ω (second harmonic of the excitation laser light) are matched, and the frequency is adjusted. In order to generate a component of 3ω (the third harmonic of the excitation laser light), a correction device 30 and a rotator 32 for rotating the polarization direction are required.

On the other hand, although the conversion efficiency of the harmonic conversion is low, the component of the frequency ω (excitation laser light) and the component of the frequency 2ω (the second harmonic of the excitation laser light) in the state where the polarization directions are orthogonal to each other are nonlinearly optically converted. A method of generating a component having a frequency of 3ω (the third harmonic of the excitation laser light) by entering the crystal 34 is also known. According to this method, the correction device 30 and the rotator 32 for rotating the polarization direction are omitted. be able to.

FIG. 6 shows a high-speed wavelength converter employing a method in which the above-described correction device 30 and rotator 32 are omitted.

4 and FIG. 5 are denoted by the same reference numerals used in FIG. 4 and FIG. 5, and detailed description of the configuration and operation is omitted.

In the high-speed wavelength converter shown in FIG. 6, since the correcting device 30 and the rotator 32 are omitted as compared with the high-speed wavelength converter shown in FIGS. 4 and 5, the configuration can be simplified. As a result, manufacturing costs can be reduced.

[0080]

As described above, the present invention has an excellent effect that the nonlinear optical crystal can be rotated at an arbitrary position at a high speed.

Further, since the present invention is configured as described above, the direction of the beam of each wavelength component separated from the converted laser beam emitted from the nonlinear optical crystal is made constant so that the optical axes coincide. It has an excellent effect that it can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a conceptual configuration of a conventional wavelength converter for obtaining a second harmonic of an excitation laser beam.

FIG. 2 is a conceptual configuration diagram of an example of an embodiment of a high-speed wavelength converter according to the present invention.

FIG. 3 is an explanatory view showing a state where a nonlinear optical crystal is attached to a galvanometer scanner, and FIG. 3 (a) is an explanatory plan view of a main part schematically showing a state where a nonlinear optical crystal is attached to a galvanometer scanner; FIG. 3B is a side view of a schematic configuration of a main part showing a state where the nonlinear optical crystal is mounted on the galvanometer scanner mounted on the gantry.

FIG. 4 is a conceptual configuration diagram of another example of the embodiment of the high-speed wavelength converter according to the present invention.

FIG. 5 is a schematic actual arrangement diagram of main parts when viewed from above the high-speed wavelength converter shown in FIG. 4;

FIG. 6 is a conceptual configuration diagram of another example of the embodiment of the high-speed wavelength converter according to the present invention.

[Explanation of symbols]

 10, 34, 36 Nonlinear optical crystal 12 Prism 14, 16 Total reflection mirror 18 Aperture plate 18a Aperture 20 Beam splitter 22 Beam position detector 24 Galvanometer scanner 30 Corrector 32 Rotator

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomoyuki Wada 2-1 Hirosawa, Wako-shi, Saitama Pref. Inventor Akio Jimbo 3-6 Photon Tuning Co., Ltd., 6-6 Minamiyoshinari, Aoba-ku, Sendai, Miyagi Prefecture

Claims (7)

[Claims] 1. A high-speed wavelength conversion device for injecting laser light into a rotatably supported nonlinear optical crystal and performing wavelength conversion of the laser light by harmonic conversion, wherein a rotating means for rotating the nonlinear optical crystal at high speed. Separating means for separating a desired harmonic component from the laser light emitted from the nonlinear optical crystal; and a desired harmonic component separated by the separating means,
A high-speed wavelength conversion device comprising: an arrangement unit for disposing the wavelength converter on a predetermined optical path. 2. The high-speed wavelength conversion device according to claim 1, wherein said rotating means rotates said nonlinear optical crystal at a high speed so that an incident angle of a laser beam with respect to a crystal axis of said nonlinear optical crystal becomes a phase matching angle. A high-speed wavelength converter. 3. The high-speed wavelength converter according to claim 1, wherein the rotating unit is a galvanometer scanner. 4. The high-speed wavelength conversion device according to claim 1, wherein the separation unit is a prism. 5. The method according to claim 1, wherein the first, second, third, or fourth aspect is selected.
In the high-speed wavelength conversion device according to the paragraph, a plurality of the nonlinear optical crystals are arranged on the same optical axis, the rotating means selectively rotates a plurality of the nonlinear optical crystals, a plurality of crystals of the nonlinear optical crystals A high-speed wavelength converter, wherein an incident angle of a laser beam with respect to an axis is selectively set to a phase matching angle. 6. The high-speed wavelength converter according to claim 1, wherein the arrangement unit is a mirror variably arranged to reflect an optical path in an arbitrary direction. A high-speed wavelength conversion device, further comprising a moving means for moving the mirror at high speed. 7. The high-speed wavelength converter according to claim 6, wherein said movable means is a galvanometer scanner.