JPH0548217A - Raman laser device utilizing unconverted pumping laser beam - Google Patents

Abstract

PURPOSE:To obtain a Stokes beam efficiently utilizing a pumping laser beam effectively by amplifying an unconverted pumping laser beam again and causing Raman conversion to occur. CONSTITUTION:The laser beam of 0.1J/pulse from an oscillator 1 is amplified into a laser beam of 1J/pulse by an amplifier 2, and amplified further into a laser beam of 4J/pulse by an amplifier 3-1. Then it strikes a Raman cell 4-1 as a pumping laser beam to cause Raman conversion to occur. A laser beam emitted from the Raman cell 4-1 contains a Stokes beam shown by a dotted line produced by the Raman conversion and an unconverted pumping laser beam shown a solid line. These mixed laser beams of different wavelengths are separated by a beam separator 5-1 into every wavelength, and taken out with independent optical paths. And only the pumping laser beam is caused to strike an amplifier 3-2 again and amplified into a laser beam of 4J/pulse like the first-stage amplifier 3-1. Then, it strikes a Ramam cell 4-2 to cause Raman conversion to occur, and only the Stokes beam is separated and taken out.

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 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 is a diagram showing a conventional Raman laser device.

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

[0004]

By the way, in order to cause Raman conversion, a powerful pump laser beam is usually required. However, the pump laser light cannot be obtained as a perfect rectangular wave, and has a waveform in which the rising and falling portions are blunted as shown in FIG. Therefore, the power of the rising portion and the falling portion of the laser pulse is not sufficient to cause the saturated Raman conversion (a region where the pump laser light is entirely used for Raman conversion), and the power is insufficient.
It becomes unconverted light as shown in. Raman conversion occurs when the pump laser light reaches a sufficient intensity, and Stokes light is obtained as shown in FIG. 2C. However, due to the transient effect, the Stokes light is delayed with respect to the pump laser light. For the rising part of the pulse,
As shown in FIG. 2B, the unconverted portion becomes larger. Usually, this unconverted light is dumped and wasted because it has an unnecessary wavelength, so the pump laser light is not effectively used, and in order to obtain a predetermined Stokes light, the pump laser system is There is a problem that the number of lasers has to be increased, the cost is increased and the installation space is also increased.

The present invention is intended to solve the above-mentioned problems, and it is possible to improve the Raman conversion efficiency by effectively utilizing the unconverted portion of the pump laser light, reduce the number of lasers in the pump laser system, and reduce the cost. It is an object of the present invention to provide a Raman laser using unconverted pump laser light, which can realize a reduction in size and space.

[0006]

According to the present invention, a Raman cell is irradiated with pump laser light and Raman-converted to obtain Stokes light. In the Raman laser apparatus, unconverted pump laser light mixed with Raman cell emission light is generated. A means for separating the Stokes light, an amplifier for amplifying at least the separated unconverted pump laser light again, and a Raman cell on which the again amplified pump laser light is incident are provided, and the unconverted pump laser light is amplified again. It is characterized in that it is made incident on a Raman cell to cause Raman conversion.

[0007]

According to the present invention, after Raman conversion, the unconverted pump laser light mixed in the emitted light of the Raman cell is separated from the generated Stokes light, and the separated unconverted pump laser light is amplified again and made incident on the Raman cell. The conversion is performed so that the pump laser light is effectively used and Stokes light can be obtained very efficiently.

[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, 4
-1, 4-2 ... are Raman cells, 5-1 and 5-2 ... are beam separation devices.

In the figure, an oscillator 1, an amplifier 2, an amplifier 3-1 and a Raman cell 4-1 have the same structure as the conventional Raman laser system shown in FIG. 1, for example, 0.1 J / pulse from the oscillator 1. 1J laser light with amplifier 2
/ Pulse, and further amplified to 4 J / pulse by the amplifier 3-1 and made incident on the Raman cell 4-1 as pump laser light to cause Raman conversion. The laser light emitted from the Raman cell 4-1 is a mixture of the Stokes light generated by Raman conversion and shown by the broken line, and the unconverted pump laser light shown by the solid line. This mixed laser light of different wavelengths,
A beam separating device 5-1 including a prism, a dichroic mirror, an etalon, a filter, etc. separates each wavelength and extracts them with an independent optical path.

In this case, when about 4 J / pulse of pump laser light is incident on the Raman cell, the optical loss in the Raman cell is about 60%, so that the energy of the pump laser light substantially transmitted is about 2.4 J / pulse. When the 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 light is made incident on the amplifier 3-2 again, and
Raman cell 4-2 after being amplified to 4 J / pulse in the same manner as in -1
The Stokes light is separated and extracted by causing Raman conversion by being incident on.

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

[0012]

As described above, according to the present invention, since the pump light is effectively used and the Stokes light can be obtained very efficiently, the load on the pump laser device can be reduced.
The number can be reduced, the system cost can be reduced, and the device space can be reduced.

[Brief description of drawings]

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

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

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

[Explanation of symbols]

1 ... Oscillator, 2, 3-1 and 3-2 ... Amplifier, 4-1 and 4
-2 ... Raman cell, 5-1 and 5-2 ... Beam separation device.

Claims (1)

[Claims] 1. Raman cell is irradiated with pump laser light,
In a Raman laser device that obtains Stokes light by Raman conversion, means for separating unconverted pump laser light mixed with Raman cell emitted light and generated Stokes light, and at least amplifying the separated unconverted pump laser light again An unconverted pump characterized by having an amplifier and a Raman cell on which the re-amplified pump laser light is incident, and amplifying the unconverted pump laser light again and injecting it into the Raman cell to cause Raman conversion. Raman laser device using laser light.