JP2750025B2 - Raman laser device using unconverted pump laser light - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Raman laser apparatus using an unconverted pump light which can be used for molecular method laser uranium enrichment, heavy metal isotope separation, and the like.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional Raman laser device.

A laser oscillator 1 comprising a carbon dioxide laser or the like
The laser light from No. 1 is passed through mirrors M-1 to M-3 to be incident on an optical amplifier 12 composed of, for example, a multi-pass cell and amplified, and the output light is extracted from mirrors M-4 and M-5. The light is incident on the amplifier 13 through the mirrors M-5 to M-8 and amplified, and the output light thereof is reflected by the mirrors M-9 to M-8.
The laser beam is incident on the Raman cell 14 through M-11 as a pump laser beam. In the Raman cell, a state transition of the medium gas occurs due to excitation by the pump laser light, Raman conversion occurs, and unconverted pump laser light and Stokes light having different wavelengths are mixed and emitted. This outgoing light is reflected by the prism 15
, And the unconverted pump laser light is absorbed by the damper 16, and the Stokes light S is separated and extracted, and is used for molecular method laser uranium enrichment, heavy metal isotope separation, and the like.

[0004]

By the way, in order to cause Raman conversion, an intense pump laser beam is usually required. However, the pump laser light cannot be obtained as a perfect rectangular wave, but has a waveform with rising and falling portions as shown in FIG. Therefore, the rising portion and the falling portion of the laser pulse do not have sufficient power to cause a saturated Raman conversion (a region where the pump laser light is entirely used for the Raman conversion), and FIG.
As shown in FIG. Raman conversion occurs when the pump laser light reaches a sufficient intensity, and Stokes light is obtained as shown in FIG. 2C. However, a delay of the Stokes light with respect to the pump laser light occurs due to a transient effect. For the rising edge of the pulse,
As shown in FIG. 2B, the unconverted portion is further increased. Normally, this unconverted light has an unnecessary wavelength and is dumped and wasted, so that the pump laser light is not effectively used. To obtain a predetermined Stokes light, the pump laser system needs to be used. It is necessary to increase the number of lasers, which raises costs and increases the installation space.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the Raman conversion efficiency is improved by effectively utilizing the unconverted portion of the pump laser light, and the number of lasers in the pump laser system is reduced to reduce the cost. It is an object of the present invention to provide a Raman laser using unconverted pump laser light, which can reduce the space and save space.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a Raman laser apparatus which irradiates a Raman cell with a pump laser beam and performs Raman conversion to obtain Stokes light. Means for separating the pump laser light and the generated Stokes light, an amplifier for re-amplifying at least the separated unconverted pump laser light, and a second Raman cell into which the re-amplified pump laser light is incident, The separated unconverted pump laser light is amplified again and is incident on a second Raman cell to cause Raman conversion.

[0007]

According to the present invention, after the Raman conversion, the unconverted pump laser light mixed with the emitted light of the Raman cell and the generated Stokes light are separated, and the separated unconverted pump laser light is amplified again and incident on the Raman cell. The conversion is caused, and the Stokes light can be obtained very efficiently by effectively utilizing the pump laser light.

[0008]

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, 1 is an oscillator, 2, 3-1 and 3-2 are amplifiers,
-1, 4-2... Are Raman cells, and 5-1, 5-2.

In the figure, an oscillator 1, an amplifier 2, an amplifier 3-1 and a Raman cell 4-1 have the same configuration as the conventional Raman laser system shown in FIG. 1 J laser light with amplifier 2
The pulse / pulse is further amplified to 4J / pulse by the amplifier 3-1 and is incident on the Raman cell 4-1 as a pump laser beam to cause Raman conversion. The laser light emitted from the Raman cell 4-1 contains a mixture of Stokes light indicated by a broken line generated by Raman conversion and unconverted pump laser light indicated by a solid line. This mixed laser light with different wavelength is
The light is separated for each wavelength by a beam separation device 5-1 including a prism, a dichroic mirror, an etalon, a filter, and the like, and is taken out with an independent optical path.

In this case, when pump laser light of about 4 J / pulse is incident on the Raman cell, the energy of the pump laser light substantially transmitted is about 2.4 J / pulse because the optical loss in the Raman cell is about 60%. If a pulse is generated and the Stokes light is generated at 1 J / pulse, the unconverted pump laser light emitted from the Raman cell becomes about 1 J / pulse, which is 1/4 of the incident pump laser light and equivalent to the Stokes light. . Therefore, only this pump laser beam is again incident on the amplifier 3-2, and the first stage amplifier 3-2
Raman cell 4-2 amplified to 4J / pulse in the same way as -1
To cause Raman conversion to separate and extract Stokes light.

The unconverted pump laser light out of the light emitted from the Raman cell 4-2 is similarly amplified repeatedly in the third and subsequent stages to cause Raman conversion. In this way, the unconverted portions of the pump light are sequentially re-amplified and used as pump laser light to cause Raman conversion, so that all pump light is effectively used and Stokes light can be obtained very efficiently.

[0012]

As described above, according to the present invention, the Stokes light can be obtained very efficiently by using the pump light effectively, so that the load on the pump laser device can be reduced.
The number can be reduced, the cost of the system can be reduced, and the device space can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating a conventional Raman laser device.

FIG. 3 is a diagram illustrating a relationship among pump light, Stokes light, and unconverted pump light.

[Explanation of symbols]

1 ... oscillator, 2,3-1,3-2 ... amplifier, 4-1,4
-2: Raman cell, 5-1 and 5-2: Beam separation device.

Claims (1)

(57) [Claims] Irradiating a Raman cell with a pump laser beam;
In a Raman laser device configured to obtain Stokes light by performing Raman conversion, a means for separating unconverted pump laser light mixed with light emitted from the first Raman cell and generated Stokes light, at least a separated unconverted pump laser has an amplifier for amplifying the light again, and a second Raman cell pump laser beam re-amplified is incident, the amount
Unconverted pump laser beam utilizing Raman laser device being characterized in that so as to cause Raman conversion and amplifies the unconverted pump laser beam away again incident on the second llamas <br/> Nseru.