JPS60249384A - Raman laser device - Google Patents

Abstract

PURPOSE:To eliminate the decrease in gain due to temperature rise by constructing the titled device in such a manner that the medium gas being introduced-in is always passed through a laser light path folding back and forth between introduced concave mirrors without being confined in the container. CONSTITUTION:An exhaust pipe 14 is connected at the top of the container 10 with the arrangement of a pair of concave-spherical reflection mirrors 11a and 11b. On the other hand, in order to keep the inner temperature of the container 10, an outer container 16 surrounding the whole container 10 by providing the space 15 is provided. The outer container 16 is installed to a supply pipe 12 and the exhaust pipe 14 and encloses the inner container 10. Besides, a supply pipe 17 and an exhaust pipe 18 to supply the space 15 with a cooling gas coming to a lower temperature of the same degree as para-hydrogen, and further to exhaust it are connected to the upper and lower parts, respectively. Continuous passing of the coolant gas without confinement by such a construction enables rapid elimination of the heat evolving with Raman conversion; therefore, the decrease in gain due to temperature rise does not occur, and Raman oscillation can be accomplished with good efficiency.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a Raman laser device.

[Technical background of the invention and its problems]

Laser technology is applied in various fields and its origins.

The exhibition is spectacular. The chemical field is also one of the fields in which it is applied, and laser light of various wavelengths is used for reaction promotion and synthesis. For example, it has been considered to utilize the rotational scattering transition of parahydrogen gas to convert carbon dioxide laser light into coherent light of around 16 μm with a Stokes shift (3s4.3m') of parahydrogen gas.

This is a type of stimulated Raman scattering, but its gain is ~
As small as 10'm', a long interaction length is required to obtain a thick conversion output. For this reason, conventionally, as shown in Fig. 2, one side has an entrance window (C) and the other side has an exit window (C).
The container (5) has a cylindrical container (5) with both side parts equipped with a gas cylinder (2G), and the inside of this container (goods) is sealed by replacing it with low-temperature parahydrogen gas.
The devices described in a) and (28b) were applied. Laser light (L) guided into the container (27) from the entrance window (5)
The light goes back and forth between the concave mirrors (28a) and (29b) multiple times, undergoes Raman conversion, and exits from the exit window (2'8b) as light of a predetermined wavelength. In the configuration in which cooled parahydrogen gas is confined within the container (27), the energy state of the gas molecules is kept at the lowest level to maximize the gain as much as possible. However, when Raman conversion occurs, the energy level of parahydrogen gas per molecule is 354.3 cm.
As a result, the temperature of the hydrogen gas increases. Such a temperature increase occurs locally in the optical path of the incident laser, and the heat is diffused to the surroundings. When the temperature of parahydrogen increases, the gain decreases and the gas becomes optically non-uniform, making it difficult to obtain high output (high repetition rates).

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a Raman laser device that rapidly eliminates the heat generated during Raman conversion and obtains highly dry pulsed light.

[Summary of the invention]

The introduced medium gas is not confined within the container, but is constantly allowed to flow between the introduced laser beam paths and back and forth between the concave mirrors, thereby eliminating the disadvantage of gain reduction due to temperature rise.

[Embodiments of the invention]

The present invention will be explained below based on the drawings showing one embodiment.

In Fig. 1, the cross-sectional shape is rectangular and has a closed box-like container (10), and both inner walls on the short side of the container have a pair of concave spherical surfaces made of high-purity copper. The reflecting mirrors (Ila) and (llb) have their reflecting surfaces facing each other. The upper and lower parts of the container α0) in the figure are each shaped like a cone that converges outward. At the top of the cone-shaped lower part is a supply pipe 0 that supplies parahydrogen gas cooled to 77K to the inside of the container α0).
2) is connected. A porous buffer filter is provided at t1[1 in the lower part of the container in order to uniformly fill the container (10) with the parahydrogen gas. In addition, a discharge pipe (141) is connected to the top of the upper part of the container 00). On the other hand, in order to maintain the internal temperature of the container 00, the entire container αO) is removed by providing a space ←ω. A surrounding outer container αe is provided. Outer container α0 is supply pipe α
and the inner container 00) attached to the discharge pipe 040 part.
In addition, a supply pipe αη and a discharge pipe O8 are connected to the upper and lower parts, respectively, for supplying and discharging a cooling gas having a temperature similar to that of the parahydrogen gas to the space σ. On both shorter sides of the container α and the outer container αQ, there are an entrance window αY and an exit window (21) on the upper and lower sides that pass through these inner containers and are airtight, respectively. The carbon dioxide laser beam (L) is mainly introduced into the upper entrance window α. In addition, in the above, 1 reflecting mirror (11a), (l
An example of each dimension of lb) is 1 width 3001
m.

The height is about 200 dragons, and the shortest part 1 of the facing distance is 4
00m, and the spherical curvature (R) is 2180 mm.

The effects of the above configuration will be described below.

First, cooling gas is supplied from the supply pipes α and aη, respectively, to maintain the inside of the inner container αC at 77K. In this state; carbon dioxide laser light (L) with a relatively high peak value
) is introduced into the inner container (10) through the entrance window (one).The introduced carbon dioxide laser light (L) passes through the reflecting mirror (lla),
(llb) and is reflected back. In this folded reflection, light in the 16 μm band is generated due to the rotational Raman transition of parahydrogen while being focused at the central portion of the reflecting surface. As a result, the carbon dioxide laser light (L) is attenuated. The above number of turns is about 20 times, and the reflection point moves downward little by little, but by the time it reaches the exit window, the carbon dioxide laser beam (L) is a coherent beam in the 16 μm band (La
) is converted to

By the way, the temperature of the parahydrogen gas inside the inner container 00) locally increases with one pulse of the carbon dioxide laser beam (L). For this purpose, the flow rate from the supply tube is set at a flow rate of, for example, 100 OP, enough to cancel out the temperature rise before the next pulsed light enters.
In the case of PS, parahydrogen gas whose temperature is constantly adjusted to 77°C is supplied at 2400 m''/s.

The parahydrogen gas exhausted through the exhaust pipe α(a) is recovered, cooled, and returned to the supply pipe (121).

〔Effect of the invention〕

By not confining the medium gas and allowing it to flow constantly.

Since the heat generated outside of the 2-Man conversion is rapidly removed, there is no decrease in gain due to temperature rise, and Raman conversion is performed efficiently. 1. Conventionally, due to slow heat diffusion,
The maximum IQPPS was repeatedly changed, but it was 100~
Now you can get 100 OPPS of repetition.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG. 2 is a perspective view showing a conventional example. α0...Container (lla), (Ilb)...Reflector α piece...Supply pipe (14), as...Discharge pipe (1 ring...Inlet window (2o)... Output window (L)・
...Carbon dioxide laser light agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2 Zuarai 26

Claims (2)

[Claims] (1) A container, a pair of concave mirrors provided on opposing sides of one of the containers with their reflective surfaces facing each other with a predetermined interval, and connected to one of the other opposing sides of the container. a supply pipe for supplying a medium gas into the interior of the container;
an exhaust pipe connected to the other opposite side of the container for exhausting the supplied medium gas; a cooling means for cooling the outer surface of the container; and a cooling means for guiding a laser beam into the interior of the container. an entrance window that is airtightly provided in the container; and an exit window that is airtightly provided in the container so that the laser light introduced from the entrance window is returned between the pair of concave mirrors and a converted beam of a predetermined wavelength is outputted. A Raman laser device comprising: (2) The Raman laser device according to claim 1, wherein the pair of concave mirrors are on the sides of the internal device.