JP3325233B2 - Laser amplifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser amplifying apparatus which forms an excitation region in a laser medium by irradiating excitation light and passes the excitation region twice to perform amplification.

[0002]

2. Description of the Related Art FIG. 29 shows, for example, the proceedings of the 56th Annual Meeting of the Japan Society of Applied Physics, 1995, No. 3, 869
5 is a configuration example of a dye laser amplifying device as a conventional laser amplifying device described on page. In the drawing, reference numeral 1 denotes a polarization beam splitter as a light separating means for separating a dye laser incident light D1 and a dye laser amplified light D2 which is a dye laser emission light, 4 denotes a polarization rotating element as a polarization control means, and 5 denotes a laser. A dye cell for accommodating a dye solution 6 as a medium, P is excitation light, 7 is a slit forming an excitation region 8, and 17 is a lens concave mirror pair as a reflecting mirror for returning laser light to the excitation region 8 again.

Next, the operation of the conventional laser amplifying device will be described. A dye solution 6, which is a dye laser medium, is sealed or circulated in the transparent dye cell 5, and when the excitation light P enters the slit 7 of the dye cell 5,
The dye molecules in the dye solution 6 are excited by absorbing light to form an excitation region 8 in the slit 7 of the dye cell 5. on the other hand,
The dye laser incident light D1 is incident as linearly polarized light in a direction that passes through the polarizing beam splitter 1, travels in the direction of a path P1 as a first optical path, is converted into circularly polarized light by a polarization rotator 4, and The first gain is obtained by passing (first time) through the excitation region 8 formed in the slit 7 of FIG. The dye laser light having the first gain is collimated by the lens concave mirror pair 17 and is reflected coaxially with the path P1 as the first optical path. The dye laser light thus reflected reverses the direction of polarization rotation with respect to the traveling direction, and passes through the excitation region 8 again (second time) to obtain a second gain. The dye laser light that has gained the second gain is again incident on the polarization rotation element 4, and the polarization rotation element 4 changes the polarization of the laser light into the circularly polarized light that has been previously inverted to the polarization direction of the dye laser incident light D 1. After being converted into linearly polarized light in the orthogonal direction, the light is reflected by the polarizing beam splitter 1 in the direction of the path P2 as a second optical path, separated from the optical axis of the dye laser incident light D1, and amplified by the dye laser amplified light. D2 is obtained.

[0004]

The conventional laser amplifying apparatus shown in FIG. 29 is constructed as described above, and the polarized light when the laser light passes through the excitation region is circularly polarized, and the laser light is opposed in the excitation region. Since the direction of polarization rotation of the laser light to be emitted becomes equal to the space, the spatial gain distribution in the excitation region is caused by the interaction between the laser light passing through the excitation region for the first time and the laser light passing through the excitation region for the second time. There is a problem that the so-called spatial hole burning occurs, the spectrum band of the laser amplified light is widened, and the intensity is temporally modulated. Also, if the polarization rotator is disposed between the dye cell and the lens concave mirror pair, the polarization of the laser light facing in the excitation region becomes orthogonal linearly polarized light, and the laser light passing through the excitation region for the first time. Interaction with the laser light that passes through the second time is less likely to occur, but the polarization direction of the laser incident light is not limited, so that the polarization direction of the laser light that passes through the second excitation area is the traveling direction of the excitation light. In the case of parallel, the energy stored in the excitation region cannot be sufficiently used for the amplification of the laser light, and the conversion efficiency from the excitation light to the laser amplified light is low, and the amplification factor is small. .

The present invention solves such a problem, obtains a large amplification factor, prevents the occurrence of spatial hole burning due to the interaction of laser light, expands the spectral band of laser amplified light, and modulates intensity over time. It is an object of the present invention to provide a laser amplifying device for suppressing the above.

[0006]

According to a first aspect of the present invention, there is provided a laser amplifying apparatus for irradiating an excitation light to form an excitation region in a laser medium and passing the laser light through the excitation region twice for amplification. First polarization control means for making the direction of polarization of laser light when passing through the excitation region for the first time parallel to the optical path of the excitation light, and laser light when passing through the excitation region for the second time A second polarization control means for making the polarization direction of the light perpendicular to the optical path of the excitation light ,
Spatial holes in the excitation region due to laser light interaction
It is characterized in that occurrence of burning is prevented .

According to a second aspect of the present invention, there is provided a laser amplifying apparatus for irradiating an excitation light to form an excitation region in a laser medium and passing the laser light twice through the excitation region to perform amplification.
An optical coupling / separating means for providing an optical path between the laser light passing the second time and the laser light passing the second time in the same direction in the excitation region;
It is characterized by preventing the occurrence of spatial hole burning in the interior .

According to a third aspect of the present invention, there is provided a laser amplifying apparatus for irradiating an excitation light to form an excitation region in a laser medium and passing laser light through the excitation region twice for amplification.
Provided optical path adjusting means for different from the optical path of the laser beam and the laser beam passing through the second time that passes in time th, the Le
Spatial hole bar in the excitation region due to laser light interaction
The feature is to prevent the occurrence of training .

According to a fourth aspect of the present invention, there is provided a laser amplifying apparatus for irradiating an excitation light to form an excitation region in a laser medium and passing the laser light twice through the excitation region to perform amplification.
An optical path adjusting means is provided for passing an optical path of the laser light passing the second time and the laser light passing the second time in parallel in the excitation region.

According to a fifth aspect of the present invention, in the laser amplifying device according to the fourth aspect, the optical path adjusting means is made of a birefringent crystal.

According to a sixth aspect of the present invention, in the laser amplifying device according to the fourth or fifth aspect, an excitation region is formed in the laser medium by irradiating the excitation light with the excitation light, and the excitation is performed by passing the excitation region twice. A first optical path adjusting means for making an optical path of the laser light passing the first time and the laser light passing the second time parallel in the excitation region, and the laser passing the second time A second coaxial optical path between the light and the laser light incident on the excitation region.
And an optical path adjusting means.

The invention according to claim 7 is the invention according to claims 3 to 6.
In the laser amplifying device according to any one of the above, a laser amplifying device that irradiates excitation light to form an excitation region in a laser medium and passes the excitation region twice to amplify the laser medium.
Optical path adjusting means for changing the optical path of the laser light passing the second time and the laser light passing the second time in the excitation area, and excitation means for adjusting the gain of the excitation area corresponding to the intensity of the laser light And characterized in that:

The invention according to claim 8 is the invention according to claims 3 to 6.
In the laser amplifying device according to any one of the above, an excitation region is formed in the laser medium by irradiating the excitation light, and the excitation is performed twice by passing through the excitation region.
An optical path adjusting means is provided in which the optical path of the laser light passing the second time and the laser light passing the second time are made different in the excitation region, and the optical path of the laser light passing the second time is arranged on the incident side of the excitation light. It is characterized by having.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a laser amplifier according to the present invention will be specifically described based on embodiments. Embodiment 1 FIG. The first embodiment is directed to an embodiment of the first aspect of the present invention, in which a laser medium is irradiated with excitation light to excite the laser medium, thereby forming an excitation region in the laser medium. Light is incident, and the laser light passes through the excitation region twice so as to amplify the laser light to obtain amplified light. The laser light passing through the excitation region for the first time and the laser light passing through the excitation region for the second time A first polarization control unit for making the polarization direction of the laser light when the laser light passes through the excitation region for the first time parallel to the traveling direction of the excitation light in the laser amplifying device in which the light is coaxial; And a second polarization control means for making the polarization direction of the laser light when the laser light passes through the excitation region for the second time perpendicular to the traveling direction of the excitation light.

As described above, the first polarization control means for making the polarization direction of the laser light when the laser light passes through the excitation region for the first time parallel to the traveling direction of the excitation light, Second direction for making the polarization direction of the laser light when passing through the excitation region for the second time perpendicular to the traveling direction of the excitation light
By limiting the polarization direction when the laser light passes through the excitation region by providing the polarization control means, the conversion efficiency from the excitation light to the laser amplified light can be increased and a large amplification factor can be obtained.

Hereinafter, description will be made with reference to FIG. The figure is a plan view showing a dye laser amplifier as a laser amplifier. In the drawing, reference numeral 1 denotes a polarization beam splitter as a light separating means for separating a dye laser incident light D1 and a dye laser amplified light D2 which is a dye laser emission light, and 2 denotes a polarization rotation as a first polarization control means. Λ / 2 wavelength plate as a specific example of the element, 3 is a polarization rotator as a second polarization control means, and a λ / 4 wavelength plate as a specific example, 5 is a dye solution as a laser medium Reference numeral 8 denotes a dye cell for accommodating the excitation light P, 8 denotes an excitation region formed in the laser medium by irradiating the excitation light P, 7 denotes a slit that allows the irradiated excitation light P to pass therethrough to define an area of the excitation region 8, 9 Is the excitation region
A total reflection mirror for returning the laser light that has passed the second time to the excitation region 8 again, D is a dye laser light, P1 is a path as a first optical path, and P2 is a path as a second optical path.

Next, this operation will be described. The transparent dye cell 5 is made of a material that is optically transparent to dye laser light D and excitation light P, such as quartz, optical glass, and sapphire. A dye solution 6 that is a laser medium is sealed. It is sealed in the slit 7 of the dye cell 5 or circulated. For example, when excitation light P such as a second harmonic of a neodymium solid laser, a copper vapor laser, an excimer laser or the like is incident on the dye solution 6 in the dye cell 5, the excitation light P causes the dye molecules in the dye solution 6 to emit light. And is excited to form an excitation region 8 along the inside of the slit 7 of the dye cell 5. On the other hand, the dye laser incident light D1 is supplied to the polarization beam splitter 1 serving as a light separating means by, for example, a λ / 2 wavelength plate serving as a first polarization controlling means.
Is transmitted as the first path P1, and the polarization direction of the dye laser light D in the excitation region 8 is controlled to be linearly polarized light that is parallel to the optical path in the traveling direction of the excitation light P.

The dye laser beam D, which has gained by passing through the excitation region 8 for the first time, is supplied to the second polarization control means, for example, λ.
After passing through the wavelength plate 4, it is converted into circularly polarized light, and is reflected coaxially by the total reflection mirror 9. The dye laser light reflected by the total reflection mirror 9 has its polarization rotation direction reversed with respect to the traveling direction, passes through the λ / 4 wavelength plate 4 again, and is polarized perpendicular to the dye laser light D passing through the excitation region 8. Converted to a direction,
Again, ie, the second time, gain is obtained by passing through the excitation region 8.
The dye laser beam D that has passed through the excitation region 8 for the second time is
The path P1 is orthogonal to the polarization direction, is reflected by the polarization beam splitter 1, is separated from the dye laser incident light D1, and the dye laser amplified light D2 is obtained.

As described above, the dye laser beam D is applied to the excitation region 8
Is controlled in parallel with the optical path in the traveling direction of the excitation light P, and the polarization direction when passing through the excitation region 8 for the second time is perpendicular to the optical path in the traveling direction of the excitation light P. Since the energy is controlled, the extraction energy at the time of passing the second time from the first time is increased, the conversion efficiency of the pump light P to the laser amplified light D2 is increased, and a large amplification factor is obtained. In addition, since the polarization direction when passing through the excitation region 8 for the first time and the polarization direction when passing through the excitation region 8 for the second time are orthogonal to each other, the first pass P that passes through the excitation region 8 for the first time is performed.
The occurrence of spatial hole burning due to the interaction between the first and second passes P2 is prevented, and the spectral band expansion and temporal intensity modulation of the laser amplified light can be suppressed.

As described above, in this embodiment, the laser light is irradiated with the excitation light P to form the excitation region 8 in the laser medium, and the laser light D is passed through the excitation region 8 twice for amplification. In the apparatus, the first polarization control means 2 for making the polarization direction of the laser beam when passing through the excitation region 8 for the first time parallel to the optical path of the excitation light P, and the excitation region 8 for the second time Second polarization control means 3 for making the polarization direction of the laser light when passing therethrough perpendicular to the optical path of the excitation light P.

FIG. 2 shows the first embodiment of the dye laser amplifying apparatus according to the first embodiment shown in FIG.
The lens 13 and the second lens 14 are added. Next, this operation will be described. The dye laser incident light D1 is supplied to the polarization beam splitter 1 as a light separating means by, for example, a λ / 2 wavelength plate as a first polarization controlling means.
Is transmitted as a first path P 1, and the polarization direction of the dye laser light D is controlled to be linearly polarized in the excitation region 8 so as to be parallel to the traveling direction of the excitation light P. Is collected and incident. The dye laser light D that has gained through the excitation region 8 is converted into collimated light by the second lens 14, and then, for example, a λ / 4 wavelength plate as a second polarization control means and a total reflection mirror 9 By combination with
The polarization direction is rotated by 90 °, condensed again on the excitation area 8 by the second lens 14 to obtain a gain, collimated by the first lens 13, and then reflected by the polarization beam splitter 1 which is a light separating means. Is separated from the dye laser incident light D1 to obtain a dye laser amplified light D2. As described above, the intensity of the dye laser beam D in the excitation region 8 can be increased, so that the amplification factor can be further improved.

FIG. 3 shows the first embodiment of the dye laser amplifying apparatus shown in FIG.
The lens pair 15 and the second lens pair 16 are added. Next, this operation will be described. The dye laser incident light D1 is, for example, λ /
The two-wavelength plate transmits the polarization beam splitter 1 as the light separating means as the first path P1 and the excitation region 8
Is controlled so that the polarization direction of the dye laser light D is parallel to the traveling direction of the excitation light P, and after being collimated by the first lens pair 15, it is incident on the excitation area 8.
The dye laser light D that has gained through the excitation region 8 is converted into collimated light by the second lens 15 and then, for example, a λ / 4 wavelength plate as second polarization control means and a total reflection mirror 9
The polarization direction is rotated by 90 ° by the combination of the above, is collimated again by the second lens pair 16, passes through the excitation region 8 to gain, is collimated by the first lens pair 15, and is a light separating means. Polarizing beam splitter 1
And is separated from the dye laser incident light D1 to obtain dye laser amplified light D2.

As described above, the size of the beam of the dye laser beam D is determined by the first lens pair 15 and the second lens pair 1.
Since the size can be converted to a size suitable for the excitation region 8 at 6, the amplification factor can be further improved. Further, in the first lens pair 15 and the second lens pair 16, noise generated from the excitation region 8 having an optical axis different from that of the dye laser beam D, that is, amplification of spontaneous emission light (Amplified Sponten).
eous Emission (hereinafter, referred to as "ASE") can be removed, so that the ratio of ASE contained in the dye laser amplified light D2 can be reduced. Further, by inserting a stop such as a pinhole at the converging position of one or both of the first lens pair 15 and the second lens pair 16 for the dye laser light D, the dye laser amplified light D2
Can be reduced.

FIG. 4 shows the dye laser amplifying apparatus according to the first embodiment shown in FIG. 3, in which the second lens pair 16 is replaced by a lens concave mirror pair 17, and the same effects as in FIG. In addition, the number of parts can be reduced.

FIG. 5 shows the dye laser amplifying apparatus according to the first embodiment shown in FIG. 3, in which the second lens pair 16 is replaced by a third lens 18 and a total reflection mirror 9.
In addition to the same effect as described above, the number of parts can be reduced.

In the first embodiment, the dye cells 5
Irradiates the excitation light P from one side with respect to
The same effect can be obtained by a configuration in which the excitation light P is irradiated from both sides. Further, in the first embodiment, the λ / 2 wavelength plate is used as the first polarization control means, but the same effect can be obtained by using the Fresnel rhomb. In the first embodiment, the λ / 4 wavelength plate is used as the second polarization control means. However, the same effect can be obtained by using a Fresnel rom or a Faraday rotator. In this embodiment, 1
Has shown a configuration in which the dye laser light is not reflected on the inner surface of the dye cell, but the same effect can be obtained by a structure in which the dye laser light is reflected on the inner surface of the dye cell.

Embodiment 2 FIG. In the second embodiment, an excitation region is formed in a laser medium by irradiating the laser medium with excitation light to excite the laser medium, and a laser beam is incident on the excitation region. In the laser amplifying device in which the laser light passing through the excitation region and the laser light passing through the excitation region for the first time and the laser light passing through the second time are coaxial, the laser light passes through the excitation region in the first time. The configuration is provided with optical coupling / separating means for making the traveling direction of the laser light passing through the same as that of the laser light passing the second time. The optical coupling / separating means referred to here is an optical coupling means for making the traveling direction of the laser light passing the first time and the laser light passing the second time the same, and a dye laser amplified light amplified by the second time passing. And light separating means for separating light.

With this configuration, it is possible to prevent the occurrence of spatial hole burning due to the interaction between the laser light passing through the excitation region for the first time and the laser light passing through the second time. , And the temporal intensity modulation can be suppressed.

Hereinafter, description will be made with reference to FIG. The figure is a plan view showing a dye laser amplifier as a laser amplifier. Reference numeral 1 in the drawing denotes a polarization beam splitter as light separating means, and the dye laser incident light D1 is incident on the polarization beam splitter 1 in a polarization direction transmitting as a first path P1. T1 and T2 are reflection mirrors as path changing means for changing the optical path in the traveling direction of the laser beam transmitted through the polarization beam splitter 1, and in this example, each is a total reflection mirror that changes the path by 90 degrees. Reference numeral 5 denotes a dye cell for storing a dye solution 6 as a laser medium, 8 denotes an excitation region formed in the laser medium by irradiating excitation light P, and 7
Reference numeral denotes a slit that allows the irradiated excitation light P to pass therethrough to define an area of the excitation area 8. T3 is a reflecting mirror as a course changing means similar to the above, and the above-described course changing means T1,
The laser beam D that has passed through the excitation region 8 via T2 is totally reflected toward the polarization beam splitter 1 as light separating means. Reference numeral 4 denotes polarization control means, which is interposed between the total reflection mirror T3 and the polarization beam splitter 1. The polarization beam splitter 1 directs the laser beam D from the polarization controller 4 in the same direction as the first path P1 in order to return the laser beam D to the excitation region 8 again. That is, at this stage, the polarization beam splitter 1 functions as an optical coupling unit that makes the traveling direction of the laser light passing the first time and the traveling direction of the laser light passing the second time the same. In addition, P1 is a path as a first optical path of the dye laser light D, and P2 is a path as a second optical path of the dye laser light D.

Next, the operation will be described. The dye laser incident light D1 is supplied to the polarization beam splitter 1
In a polarization direction that transmits as a first path P1,
The light is reflected by the first total reflection mirror T1 and the second total reflection mirror T2, and passes through the excitation region 8. The dye laser light D that has gained by passing through the excitation region 8 is rotated by 90 ° when it passes through, for example, a λ / 2 wavelength plate 4 which is a polarization control means, and is polarized by the third total reflection mirror T3. Splitter 1
And is reflected by the polarizing beam splitter 1. The dye laser light D reflected by the polarization beam splitter 1 is
As a second pass, after passing through the same optical path as the first pass and passing through the pumping region 8 again to obtain a gain, the polarization direction is further rotated by 90 ° by the λ / 2 wave plate 4 and the polarization beam splitter 1 And is separated from the dye laser incident light D1 to obtain dye laser amplified light D2.

As described above, the dye laser beam D is applied to the excitation region 8
Since the traveling direction when passing through the excitation region 8 for the first time and the traveling direction when passing through the excitation region 8 for the second time are the same, the first path P1 that passes through the excitation region 8 for the first time and the first path P1 that passes through the excitation region 8 for the second time 2 prevents the occurrence of spatial hole burning due to the interaction with the second path P2, thereby suppressing the expansion of the spectral band of the laser amplified light and the temporal intensity modulation.

In the second embodiment, the dye cells 5
Irradiates the excitation light P from one side with respect to
The same effect can be obtained by a configuration in which the excitation light P is irradiated from both sides. In the second embodiment, a λ / 2 wavelength plate is used as the polarization control means. However, the same effect can be obtained by using a Fresnel rhomb. Further, in the second embodiment, the configuration is described in which the dye laser light is not reflected on the inner surface of the dye cell. However, the same effect can be obtained by a configuration in which the dye laser light is reflected on the inner surface of the dye cell.

As described above, the second embodiment provides a laser amplifying device that irradiates excitation light to form an excitation region in a laser medium and passes laser light twice through the excitation region to perform amplification. And an optical coupling / separating means for making the optical path of the laser light passing through the second region and the laser light passing through the second time in the same direction in the excitation region.

Embodiment 3 The third embodiment is directed to a laser amplifying device that amplifies a laser beam by passing the laser beam twice through the excitation region, wherein the laser beam passing through the first excitation region and the laser beam passing through the second excitation region are different from each other. An optical path adjusting means for adjusting the laser light so as not to overlap in the excitation area is provided to prevent the occurrence of spatial hole burning due to the interaction between the laser light passing the first time and the laser light passing the second time in the excitation area. The configuration is such that the expansion of the spectrum band of the amplified light and the temporal intensity modulation can be suppressed.

Hereinafter, description will be made with reference to FIGS. 7 and 8. FIG. 7 is a plan view showing a dye laser amplifier as a laser amplifier, and FIG. 8 is a sectional view thereof. In the drawing, reference symbol D1 denotes a dye laser incident light, 1 denotes a polarization beam splitter which is a light separation unit, and 4 denotes a polarization control unit such as λ.
A / 4 wavelength plate, 8 is an excitation area, and 9 is a total reflection mirror as an optical path changing means functioning as an optical path adjusting means.

Next, the operation will be described. The dye laser incident light D1 is supplied to the polarization beam splitter 1
In a polarization direction that transmits as a first path P1,
It passes through the excitation region 8. The dye laser beam D that has passed through the excitation region 8 and gained is used as polarization control means, for example, λ / 4.
After passing through the wave plate 4, the light is converted into circularly polarized light, and is reflected by a total reflection mirror 9 as an optical path polarizing means. Here, by inclining the incident angle of the dye laser light D to the total reflection mirror 9 from vertical incidence, when the dye laser light D passes through the excitation region 8 again as the second path P2, the first path P1 It is set so that the light passes through the excitation region 8 in different optical paths and gain is obtained there. The second path P2 that has passed through the excitation region 8
Has a polarization direction orthogonal to the dye laser incident light, is reflected by the polarization beam splitter 1, and is incident on the dye laser incident light D1.
And the dye laser amplified light D2 is obtained.

As described above, the dye laser beam D is applied to the excitation region 8
Pass through different regions when passing through the excitation region 8 for the first time and when passing through the excitation region 8 for the second time.
The first pass P1 passing the second time and the second passing P2 the second time
, The spatial hole burning due to the interaction with the path P2 is prevented, and the expansion of the spectral band of the laser amplified light and the temporal intensity modulation can be suppressed.

In the third embodiment, the dye cells 5
Irradiates the excitation light P from one side with respect to
The same effect can be obtained by a configuration in which the excitation light P is irradiated from both sides. Further, in the third embodiment, a λ / 4 wavelength plate is used as the polarization control means, but the same effect can be obtained by using a Fresnel rom or a Faraday rotator.
Further, in the third embodiment, the configuration in which the dye laser light is not reflected on the inner surface of the dye cell has been described. However, the same effect can be obtained by the structure in which the dye laser light is reflected on the inner surface of the dye cell.
Further, in the third embodiment, the polarization is controlled by the combination of the polarization beam splitter 1 and the λ / 4 wavelength plate 3, and the dye laser amplified light D2 is separated from the dye laser incident light D1. Is omitted and the polarization beam splitter 1
Instead, a total reflection mirror may be used. In this case, when the polarization direction of the dye laser light D is perpendicular to the polarization direction of the excitation light P, the amplification factor can be further improved.

As described above, according to the third embodiment, a laser amplifying apparatus for irradiating an excitation light to form an excitation region in a laser medium and passing laser light twice through the excitation region to amplify the laser light. In this configuration, an optical path adjusting means for changing the optical path between the laser light passing first and the laser light passing second is provided.

Embodiment 4 FIG. The fourth embodiment differs from the third embodiment in that the optical paths of the laser light passing the first time through the excitation region and the laser light passing through the second time are made different so as not to overlap in the excitation region. By providing an optical path adjusting means that passes through the excitation region in parallel, it is possible to prevent the occurrence of spatial hole burning due to the interaction between the laser light that first passes through the excitation region and the laser light that passes through the second time, In addition to the expansion of the spectral band of the laser amplified light and the suppression of temporal intensity modulation, the ratio of the volume of the laser light passing through the volume of the excitation region can be increased, and the conversion from the pump light to the laser amplified light can be performed. The configuration is such that a large amplification factor can be obtained by increasing the efficiency.

Hereinafter, description will be made with reference to FIGS. 9 and 10. FIG. 9 is a plan view showing a dye laser amplifier as a laser amplifier, and FIG. 10 is a sectional view thereof. The same components as those in the third embodiment are denoted by the same reference numerals, and description thereof is omitted. Reference numeral 18 in the drawing denotes a lens as an optical path adjusting means, so that the optical path of the laser light passing the first time through the excitation area and the optical path of the laser light passing through the second time are parallel to the excitation area without overlapping. Is set.

Next, the operation will be described. The dye laser incident light D1 is supplied to the polarization beam splitter 1
In a polarization direction that transmits as a first path P1,
It passes through the excitation region 8. The dye laser beam D that has passed through the excitation region 8 and gained is used as polarization control means, for example, λ / 4.
After passing through the wave plate 4, the light is converted into circularly polarized light, collected by a third lens 18 as an optical path adjusting means, and is totally reflected by a total reflection mirror 9.
Is incident on. Here, the first pass P of the dye laser light D
The optical path is adjusted by shifting the optical axis of the first lens from the center of the third lens 18, and when the light is reflected by the total reflection mirror 9, passes through the third lens 18 again, and passes through the excitation area 8, the first Is parallel to the optical axis of the path P1, and does not overlap with the first path P1. The second path P2 that has passed through the excitation region 8 has a polarization direction orthogonal to the dye laser incident light D1, is reflected by the polarization beam splitter 1, is separated from the dye laser incident light D1, and forms the dye laser amplified light D2. can get.

FIGS. 11 and 12 show the third lens 18 and the total reflection mirror 9 as optical path adjusting means in the dye laser amplifying apparatus according to the fourth embodiment shown in FIG. FIG. 11 is a plan view, and FIG. 12 is a cross-sectional view, showing a form in which the prism 21 is a crystal. This embodiment has the same effect as that of the embodiment shown in FIG. 9 and can reduce the number of constituent parts as compared with the above embodiment. Further, in this embodiment, the prism and the dye cell are shown as separate structures. However, the same effect as that of the embodiment shown in FIG. In addition, the device can be made compact.

As shown in FIGS. 9 to 12, in the fourth embodiment, an excitation region is formed in a laser medium by irradiating excitation light, and laser light is passed twice through the excitation region to perform amplification. The laser amplifying apparatus is provided with an optical path adjusting means for passing the optical path of the laser light passing the first time and the laser light passing the second time in parallel in the excitation region.

With this configuration, the dye laser beam D passes through different regions in the excitation region 8 when passing through the excitation region 8 for the first time and when passing through the excitation region 8 for the second time. Pass the first pass P
The occurrence of spatial hole burning due to the interaction between the first and second passes P2 is prevented, and the spectral band expansion and temporal intensity modulation of the laser amplified light can be suppressed. In addition, the dye laser beam D illuminates the excitation region 8 by 1
Since the optical axes of the second and the second pass are parallel, the transmission area of the dye laser light D occupying the excitation area 8 can be increased, and the energy conversion efficiency from the excitation light P to the dye laser amplified light D2 can be increased. Can be improved.

In the fourth embodiment, the dye cells 5
Irradiates the excitation light P from one side with respect to
The same effect can be obtained by a configuration in which the excitation light P is irradiated from both sides. In the fourth embodiment, a λ / 4 wavelength plate is used as the polarization control means. However, the same effect can be obtained by using a Fresnel rhomb or a Faraday rotator.
Further, in the fourth embodiment, a configuration in which the dye laser light is not reflected on the inner surface of the dye cell has been described. However, the same effect can be obtained by a structure in which the dye laser light is reflected on the inner surface of the dye cell.
Further, in the fourth embodiment, the polarization is controlled by the combination of the polarization beam splitter 1 and the λ / 4 wavelength plate 3, and the dye laser amplified light D2 is separated from the dye laser incident light D1. 3 is omitted, and the polarization beam splitter 1 is omitted.
Instead, a total reflection mirror may be used. In this case, if the polarization direction of the dye laser light D is perpendicular to the polarization direction of the excitation light P, the amplification factor can be further improved.

Embodiment 5 In the fifth embodiment, in the fourth embodiment, the optical path of the laser light that passes through the excitation region for the first time and the optical path of the laser light that passes through the second time are passed through the excitation region without being overlapped. This is a configuration using a birefringent crystal as an optical path adjusting means. FIG.
3 is a plan view and FIG. 14 is a sectional view thereof. The same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Reference numeral 30 in the figure denotes a birefringent crystal used as an optical path adjusting unit. Examples of the birefringent crystal include calcite and quartz.

Next, the operation will be described. The dye laser incident light D1 is supplied to the polarization beam splitter 1
In a polarization direction that transmits as a first path P1,
It passes through the excitation region 8. The dye laser light D that has gained by passing through the excitation region 8 passes through a birefringent crystal 30 as an optical path adjusting unit, and becomes circularly polarized light when passing through, for example, a λ / 4 wavelength plate 4 as a polarization controlling unit. It is converted and reflected coaxially with the first path P1 by the reflection by the total reflection mirror 9, and again λ / 4
The light is converted into a polarization direction orthogonal to the first path P1 by the wave plate, and is incident on the birefringent crystal 30 again. Birefringent crystal 30
Since the polarization direction of the second path P2 passing through the first path P1 is orthogonal to that of the first path P1, the refraction angle is different, and the gain is obtained by passing through the excitation region 8 with an optical axis different from that of the first path P1. . Here, the optical path length in the birefringent crystal 30 is set to the first value in the excitation region 8.
The dye laser light D is set so as not to overlap between the second pass and the second pass. Second path P that has passed through excitation region 8
2 has a polarization direction orthogonal to the dye laser incident light D1, is reflected by the polarization beam splitter 1, is separated from the dye laser incident light D1, and obtains a dye laser amplified light D2.

As described above, the dye laser beam D is applied to the excitation region 8
Pass through different regions when passing through the excitation region 8 for the first time and when passing through the excitation region 8 for the second time.
The first pass P1 passing the second time and the second passing P2 the second time
To prevent the occurrence of spatial hole burning due to the interaction with the path P2, and can suppress the expansion of the spectral band of the laser amplified light and the temporal intensity modulation.

FIG. 15 shows a fourth embodiment of the dye laser amplifying apparatus according to the fifth embodiment shown in FIGS. 13 and 14, in which the fourth lens 19 is provided on the optical axis, that is, on the optical path of the dye laser incident light D1, and the birefringent crystal 30 and the polarized light. A second lens 14 is provided between the control unit and the λ / 4 wavelength plate 3, and the dye laser amplified light D2
And the fifth lens 20 is interposed on the optical path of the third embodiment. With this configuration, as in Embodiment 1 shown in FIG. 2, the intensity of the dye laser beam D in the excitation region 8 can be increased, so that the amplification factor can be further improved.

FIG. 17 shows a first lens on the optical axis of the dye laser beam D between the polarization beam splitter 1 and the excitation region 8 in the dye laser amplifier of the fifth embodiment shown in FIGS. A pair 15 is provided, and a second lens pair 16 is provided between the λ / 4 wavelength plate 3 as the polarization control means and the total reflection mirror 9. With this configuration, similarly to Embodiment 1 shown in FIG. 3, the beam size of the dye laser beam D is large enough to fit the excitation region 8 in the first lens pair 15 and the second lens pair 16. Since it can be converted to a size, the amplification factor can be further improved.
The first lens pair 15 and the second lens pair 1
6, an excitation region 8 having an optical axis different from that of the dye laser beam D
Can be removed, so that the ratio of ASE contained in the dye laser amplified light D2 can be reduced. further,
By inserting a stop such as a pinhole at the focusing position of one or both of the first lens pair 15 and the second lens pair 16 for the dye laser light D, the ASE contained in the dye laser amplified light D2 can be further increased. Can be reduced. Further, similar to the first embodiment shown in FIG. 4, when the combination of the second lens pair 16 and the total reflection mirror 9 is replaced with a pair of a lens and a concave mirror, the same effect as described above can be obtained, and the components can be obtained. The score can be reduced.

In the fifth embodiment, the dye cells 5
Irradiates the excitation light P from one side with respect to
The same effect can be obtained by a configuration in which the excitation light P is irradiated from both sides. In the fifth embodiment, a λ / 4 wavelength plate is used as the polarization control means. However, the same effect can be obtained by using a Fresnel rom or a Faraday rotator.
In the fifth embodiment, the configuration in which the dye laser light is not reflected on the inner surface of the dye cell is shown. However, the same effect can be obtained by the structure in which the dye laser light is reflected on the inner surface of the dye cell.
In the fifth embodiment, the birefringent crystal and the dye cell are shown as separate components. However, the birefringent crystal is bonded to the dye cell, or the dye cell is made of a birefringent crystal and integrated. The same effects can be achieved with the configuration, and the device can be made compact.

Embodiment 6 FIG. The sixth embodiment is different from the fourth or fifth embodiment in that the optical path of the laser light passing the first time through the excitation region and the optical path of the laser light passing the second time do not overlap in the excitation region and are parallel. The first to pass
And a second optical path adjusting means for making the optical path of the laser light that has passed through the excitation area a second time and the optical path of the laser light incident on the excitation area coaxial. . With this configuration, it is easy to adjust the optical axis with the laser oscillator or another amplifier.

Hereinafter, description will be made with reference to FIGS. 19 and 20. FIG. 19 is a plan view and FIG. 20 is a sectional view thereof.
In the figure, reference numeral 30 denotes a birefringent crystal as first optical path adjusting means, and 31 denotes a birefringent crystal as second optical path adjusting means, which are arranged on the optical paths on both sides of the excitation region 8, respectively.

Next, the operation will be described. The dye laser incident light D1 is supplied to the polarization beam splitter 1
In a polarization direction that transmits as a first path P1,
For example, the light passes through the excitation region 8 through a birefringent crystal 31 as a second optical path adjusting means such as calcite or quartz. The dye laser light D having gained by passing through the excitation region 8 passes through the first birefringent crystal 30 as the next optical path adjustment, and then passes through the polarization control means, for example, the λ / 4 wavelength plate 3, to form a circle. The light is converted into polarized light, is reflected coaxially with the first path P1 by the total reflection mirror 9, is converted again into a polarization direction orthogonal to the first path P1 by the λ / 4 wavelength plate 3, and is again adjusted in the first optical path. It is incident on a birefringent crystal 30 as a means. The second path P2 passing through the first birefringent crystal 30 has a different refraction angle because the polarization direction is orthogonal to the first path P1, and is excited by an optical axis different from that of the first path P1. Gain is obtained through region 8. Here, the optical path adjusting means is adjusted so that the optical path length in the first birefringent crystal 30 does not overlap the dye laser beam D between the first path P1 and the second path P2 in the excitation region 8. The second path P2 passing through the excitation region 8 has a polarization direction orthogonal to the dye laser incident light D1, and is returned to the same optical axis as the dye laser incident light D1, that is, on the optical path by the second birefringent crystal 31. Is reflected by the polarization beam splitter 1, is separated from the dye laser incident light D1, and is amplified by the dye laser amplified light D2.
Is obtained.

As described above, the dye laser beam D passes through different regions when passing through the excitation region 8 for the first time and when passing through the excitation region 8 for the second time.
The first pass P1 passing the second time and the second passing P2 the second time
To prevent the occurrence of spatial hole burning due to the interaction with the path P2, and can suppress the expansion of the spectral band of the laser amplified light and the temporal intensity modulation. Further, since the optical axes of the dye laser incident light D1 and the dye laser amplified light D2 are on the same plane, the arrangement of the optical components becomes easy.

As described above, in the sixth embodiment, in the laser amplifying device according to the fourth or fifth embodiment, the optical path of the first-passed laser beam and the second-passed laser beam is set in the excitation region. First optical path adjusting means for making the optical path parallel,
A second optical path adjusting means for making the optical path of the laser light passed through the second time and the laser light incident on the excitation region coaxial is provided.

FIG. 21 shows the dye laser amplifying apparatus according to the sixth embodiment shown in FIG. 19, in which the first lens 13 is provided between the polarizing beam splitter 1 and the second birefringent crystal 31, and the second lens is provided. Birefringent crystal 30 and λ / 4 as polarization control means
The second lens 14 is interposed between the second lens 14 and the wave plate 3. FIG. 22 is a sectional view of FIG. With this configuration, the intensity of the dye laser light D in the excitation region 8 can be increased as in the first embodiment shown in FIG.
The amplification factor can be further improved.

FIG. 23 shows a first lens pair 15 on the optical axis of the dye laser beam D between the polarization beam splitter 1 and the excitation region 8 in the dye laser amplifier of the sixth embodiment shown in FIG. Further, a second lens pair 16 is interposed between the λ / 4 wavelength plate 3 as the polarization control means and the total reflection mirror 9. With this configuration, similarly to Embodiment 1 shown in FIG. 3, the size of the beam of the dye laser beam D is adjusted by the first lens pair 15 and the second lens pair 16 to a size suitable for the excitation region 8. , So that the amplification factor can be further improved. In the first lens pair 15 and the second lens pair 16, A generated from the excitation region 8 having an optical axis different from that of the dye laser light D
Since SE can be removed, the ratio of ASE contained in the dye laser amplified light D2 can be reduced. Further, by inserting a stop such as a pinhole at the converging position of one or both of the first lens pair 15 and the second lens pair 16 for the dye laser light D, the light is further included in the dye laser amplified light D2. ASE ratio can be reduced. Similar to the first embodiment shown in FIG. 4, the same effect is obtained even when the combination of the second lens pair 16 and the total reflection mirror 9 is replaced with a pair of a lens and a concave mirror, and the number of parts is reduced. Can be reduced.

In the sixth embodiment, the dye cells 5
Irradiates the excitation light P from one side with respect to
The same effect can be obtained by a configuration in which the excitation light P is irradiated from both sides. In the sixth embodiment, a λ / 4 wavelength plate is used as the polarization control means. However, the same effect can be obtained by using a Fresnel rom or a Faraday rotator.
Further, in the sixth embodiment, the configuration in which the dye laser light is not reflected on the inner surface of the dye cell has been described. However, the same effect can be obtained by the structure in which the dye laser light is reflected on the inner surface of the dye cell.
In the sixth embodiment, the birefringent crystal and the dye cell are shown as separate components. However, the birefringent crystal is bonded to the dye cell, or the dye cell is made of a birefringent crystal and integrated. The same effects can be achieved with the configuration, and the device can be made compact.

Embodiment 7 FIG. In the seventh embodiment, in the configuration of the third to sixth embodiments described above, a configuration is provided in which excitation means for adjusting the gain of the excitation region in accordance with the intensity of the laser light is provided. With such a configuration, the gain in the excitation region can be adjusted, the conversion efficiency from the excitation light to the laser amplified light can be increased, and a large amplification factor can be obtained.

Hereinafter, description will be made with reference to FIG. The figure is a side view showing an excitation means of a dye laser amplification device as a laser amplification device. Reference numeral 40 in FIG.
The excitation means includes a transfer lens 42, a rectangular waveguide 41, an optical fiber 43, and the like. Note that the same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Next, the operation will be described. The dye laser light D is emitted by the optical path adjusting means or the like described in the third to sixth embodiments in a state where the optical paths do not overlap in the excitation region 8.
The first path P1 and the second path P2 are arranged in a direction perpendicular to the traveling direction of the pump light P. On the other hand, the excitation light P is
The space is transmitted by a mirror or an optical fiber 40 and is incident on the excitation region 8. At this time, the excitation light P is irradiated on the dye solution 6 by the excitation means 43, for example, a combination of a two-stage rectangular waveguide 41 and a transfer lens 42. As a result, an excitation region 8 is formed. At this time, as shown in FIG. 26, for example, the excitation high intensity in the region where the dye laser beam D passes through the second pass P2 is larger than that in the region where the dye laser beam D passes through the first pass P1. The dye laser amplified light D2 is obtained by controlling the excitation means 43.

As described above, since the dye laser beam D has different gains in the first path P1 and the second path P2 passing through the pumping region 8, the intensity distribution of the pumping light P is determined by the pumping means. By adjusting at 40, the energy conversion efficiency from the excitation light P to the dye laser amplified light D2 can be freely improved.

In the seventh embodiment, the dye cells 5
Irradiates the excitation light P from one side with respect to
The same effect can be obtained by a configuration in which the excitation light P is irradiated from both sides.

As described above, in the seventh embodiment, in the laser amplifying device according to any of the third to sixth embodiments, the laser light passing through the first time and the laser light passing through the second time are used. In addition to the optical path adjusting means for making the optical path different in the excitation area, the excitation means for adjusting the gain of the excitation area according to the intensity of the laser beam is provided.

Embodiment 8 FIG. The eighth embodiment is different from the third to sixth embodiments in that the optical paths of the laser light passing through the excitation region for the first time and the laser light passing the second time do not overlap in the excitation region, and An optical path adjusting means for arranging the optical path of the laser light passing through the excitation region in the direction is provided. FIG. 27 is a side view showing the excitation means of the dye laser amplification device as the laser amplification device. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

With this configuration, the laser beam that passes the first time and the optical path of the laser light that passes the second time do not overlap in the excitation region, and the laser light that passes through the excitation region in the traveling direction of the excitation light. By providing the optical path adjusting means for arranging the optical paths of the above, the gain of the laser medium can be selected according to the intensity of the laser light, and the conversion efficiency from the excitation light to the laser amplified light can be increased to obtain a large amplification factor.

Next, the operation will be described. The dye laser light D is supplied to the first path P1 and the second path P2 by the optical path adjusting means described in the third to sixth embodiments in a state where the optical paths of the laser light do not overlap in the excitation region 8. In the direction parallel to the traveling direction of the
Is arranged on the excitation light incident side. On the other hand, the excitation light P is
The space is transmitted by a mirror or an optical fiber 40, and is incident on the excitation region 8. In the excitation region 8, the excitation light P is absorbed by the dye molecules in the dye solution 6, so that the intensity of the light is attenuated as it progresses. An intensity distribution as shown in FIG. Therefore, the intensity of the excitation light in the region where the dye laser beam D passes through the second pass P2 is larger than that in the region where the dye laser beam D passes through the excitation region 8 by the first pass P1.

As described above, the dye laser beam D is applied to the excitation region 8
Different gains are obtained in the first path P1 and the second path P2 which pass through the filter, and the intensity distribution of the excitation light P can be adjusted by adjusting the concentration of the dye molecules in the dye solution 6, so that the excitation light can be adjusted. Energy conversion efficiency from P to dye laser amplified light D2 can be freely increased.

As described above, in the eighth embodiment, in the laser amplifying device according to any one of claims 3 to 6, the laser light passing through the first time and the laser light passing through the second time are used. The optical path is different in the excitation region, and the optical path of the laser light that passes the second time is arranged on the incident side of the excitation light.

[0072]

According to the first to eighth aspects of the present invention,
By limiting the polarization direction of the laser light when passing through the excitation region, the conversion efficiency from the excitation light to the laser amplified light can be increased to obtain a large amplification factor, and the laser light passing through the polarization direction or the excitation region can be obtained. Restricting the optical path of the laser beam prevents the occurrence of spatial hole burning due to the interaction between the laser light passing through the excitation region for the first time and the laser light passing through the second time. It is possible to provide a laser amplifying device that suppresses a specific intensity modulation.

According to the first aspect of the present invention, the first polarization control means for making the polarization direction of the laser light when the laser light passes through the excitation region for the first time parallel to the traveling direction of the excitation light. And second polarization control means for making the polarization direction of the laser light when the laser light passes through the excitation region for the second time perpendicular to the traveling direction of the excitation light, so that the laser light passes through the excitation region. It is possible to restrict the polarization direction at the time of performing, and to increase the conversion efficiency from the excitation light to the laser amplified light to obtain a large amplification factor.

According to the second aspect of the present invention, the laser beam passing through the excitation region for the first time and the laser beam passing through the excitation region in the second time have the same coupling direction by the optical coupling / separating means. Can prevent the occurrence of spatial hole burning due to the interaction between the laser light passing the first time and the laser light passing the second time, thereby suppressing the expansion of the spectral band of the laser amplified light and the temporal intensity modulation. can do.

According to the third aspect of the present invention, the optical path adjusting means can adjust the laser light passing through the excitation region for the first time and the laser light passing the second time so as not to overlap in the excitation region. Spatial hole burning due to the interaction between the laser light passing the second time and the laser light passing the second time can be prevented, and the expansion of the spectral band of the laser amplified light and the temporal intensity modulation can be suppressed. it can.

According to the fourth aspect of the present invention, the laser light passing through the excitation region for the first time and the laser light passing through the second time can pass in the excitation region in parallel without overlapping by the optical path adjusting means. In addition, it is possible to prevent the occurrence of spatial hole burning due to the interaction between the laser light passing through the excitation region for the first time and the laser light passing through the second time, thereby expanding the spectral bandwidth and temporal intensity of the laser amplified light. In addition to being able to suppress modulation, it is possible to increase the ratio of the volume through which the laser beam passes to the volume of the excitation region, thereby increasing the conversion efficiency from the excitation light to the laser amplified light and obtaining a large amplification factor. Can be.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the laser light passing through the excitation region for the first time and the laser light passing through the second time pass in the excitation region in parallel without overlapping. Since the optical path adjusting means is made of a birefringent crystal, the optical system can be easily adjusted.

According to the sixth aspect of the present invention, in the fourth or fifth aspect of the present invention, the first and second laser beams passing through the excitation region do not overlap in the excitation region, and A laser oscillator or another amplifier is provided by a first optical path adjusting means for passing the laser light in parallel and a second optical path adjusting means for making the laser light passing through the excitation area a second time and the laser light incident on the excitation area coaxial. Can be easily adjusted.

According to a seventh aspect of the present invention, in the third to sixth aspects of the present invention, the gain in the excitation region is adjusted by the excitation means for adjusting the gain in the excitation region in accordance with the intensity of the laser beam. Thus, the conversion efficiency from the excitation light to the laser amplified light can be increased, and a large amplification factor can be obtained.

According to the eighth aspect of the present invention, in the third to sixth aspects of the present invention, the optical path adjusting means causes the laser light passing through the first and second passes through the excitation region. The laser light passing through the excitation region can be arranged on the side of the pump light traveling direction without overlapping, so that the gain of the laser medium can be selected according to the laser light intensity, and the conversion from pump light to laser amplified light The efficiency can be increased to obtain a large amplification factor.

[Brief description of the drawings]

FIG. 1 is a plan view showing a laser amplification device according to a first embodiment.

FIG. 2 is a plan view showing another laser amplification device according to the first embodiment.

FIG. 3 is a plan view showing another laser amplification device according to the first embodiment.

FIG. 4 is a plan view showing another laser amplification device according to the first embodiment.

FIG. 5 is a plan view showing another laser amplification device according to the first embodiment.

FIG. 6 is a plan view showing a laser amplification device according to a second embodiment.

FIG. 7 is a plan view showing a laser amplification device according to a third embodiment.

FIG. 8 is a sectional view of FIG. 7;

FIG. 9 is a plan view showing a laser amplification device according to a fourth embodiment.

FIG. 10 is a sectional view of FIG. 9;

FIG. 11 is a plan view showing another laser amplification device according to the fourth embodiment.

FIG. 12 is a sectional view of FIG.

FIG. 13 is a plan view showing a laser amplification device according to a fifth embodiment.

FIG. 14 is a sectional view of FIG.

FIG. 15 is a plan view showing another laser amplification device according to the fifth embodiment.

FIG. 16 is a sectional view of FIG.

FIG. 17 is a plan view showing another laser amplification device according to the fifth embodiment.

18 is a sectional view of FIG.

FIG. 19 is a plan view showing another laser amplification device according to the sixth embodiment.

20 is a sectional view of FIG.

FIG. 21 is a plan view showing another laser amplification device according to the sixth embodiment.

FIG. 22 is a sectional view of FIG. 21;

FIG. 23 is a plan view showing another laser amplification device according to the sixth embodiment.

FIG. 24 is a sectional view of FIG. 23;

FIG. 25 is a side view showing the excitation means of the seventh embodiment.

FIG. 26 is a diagram showing an intensity distribution of excitation light according to the seventh embodiment.

FIG. 27 is a side view showing an excitation unit of the eighth embodiment.

FIG. 28 is a diagram showing an intensity distribution of excitation light according to the eighth embodiment.

FIG. 29 is a plan view showing a conventional laser amplifying device.

[Explanation of symbols]

1 polarization beam splitter, 2 λ / 2 wavelength plate, 3 λ
/ 4 wavelength plate, 5 dye cell, 6 dye solution, 7 slit, 8 excitation area, 9 total reflection mirror, 13 first lens, 14 second lens, 15 first lens pair, 1
6 Second lens pair, 17 lens concave mirror pair, 18
3rd lens, 19 4th lens, 20 5th lens, 30 1st birefringent crystal, 31 2nd birefringent crystal, 40 Excitation means, 41 Rectangular waveguide, 42 Transfer lens, 43 Optical fiber, D Dye laser light, D1
Dye laser incident light, D2 dye laser amplified light, P1 first pass, P2 second pass, P excitation light.

Continuation of the front page (72) Inventor Ichiro Kobayashi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Shuichi Fujita 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (56) reference Patent flat 10-215018 (JP, a) JP flat 5-90680 (JP, a) JP flat 5-198875 (JP, a) (58 ) investigated the field (Int.Cl. ⁷ H01S 3/00-3/30 JICST file (JOIS)

Claims (8)

(57) [Claims] 1. A laser amplifying device for irradiating an excitation light to form an excitation region in a laser medium and passing laser light through the excitation region twice to amplify the laser light when the laser light passes through the excitation region for the first time. First polarization control means for making the polarization direction of the laser light parallel to the optical path of the excitation light, and changing the polarization direction of the laser light when passing through the excitation region for the second time with respect to the optical path of the excitation light. And second polarization control means for making the laser beams perpendicular to each other.
Of Spatial Hole Burning in the Excitation Region by the Action
A laser amplifying device for preventing production . 2. A laser amplifying device for irradiating an excitation light to form an excitation region in a laser medium and passing the laser light through the excitation region twice to amplify the laser light. An optical coupling / separating means for making an optical path of the laser beam passing through the laser beam in the same direction in the excitation region;
A laser amplifying device for preventing spatial hole burning from occurring in a region . 3. A laser amplifying apparatus for irradiating an excitation light to form an excitation region in a laser medium and passing laser light through the excitation region twice to amplify the laser light. Providing an optical path adjusting means for making an optical path different from the laser light passing through the second time ;
Spatial holes in the excitation region due to laser light interaction
A laser amplifying device for preventing generation of burning . 4. A laser amplifying apparatus for irradiating an excitation light to form an excitation region in a laser medium and passing the laser light through the excitation region twice to amplify the laser light. 4. The laser amplifying device according to claim 3, further comprising an optical path adjusting means for passing an optical path of the laser beam passing through the excitation region in parallel with the laser beam. 5. The laser amplifying device according to claim 4, wherein the optical path adjusting means is made of a birefringent crystal. 6. A laser amplifying device for irradiating an excitation light to form an excitation region in a laser medium, passing the excitation region twice, and amplifying the laser light, wherein the laser light passing through a first time and the laser light passing through a second time A first optical path adjusting means for making an optical path with the laser light parallel in the excitation region, and a second optical path adjusting means for making the optical path of the laser light passed through the second time and the laser light incident on the excitation region coaxial. The laser amplifying device according to claim 4 or 5, further comprising two optical path adjusting means. 7. A laser amplifying apparatus for irradiating an excitation light to form an excitation region in a laser medium, passing the excitation region twice, and amplifying the laser light, wherein the laser light passing through the first time and the laser light passing through the second time 4. An apparatus according to claim 3, further comprising: an optical path adjusting unit that changes an optical path of the laser light to the excitation region in the excitation region; and an excitation unit that adjusts a gain of the excitation region in accordance with the intensity of the laser light. The laser amplifying device according to claim 6. 8. A laser amplifying device that forms an excitation region in a laser medium by irradiating an excitation light and passes the laser light through the excitation region twice to amplify the laser light. 4. An optical path adjusting means, wherein an optical path with the laser light is made different in the excitation region and an optical path of the laser light which passes for the second time is arranged on an incident side of the excitation light. 7. The laser amplifier according to any one of 6.