JP2009071203A - Waveguide laser oscillation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the reflection loss by a half-mirror, a reflecting mirror and a total reflection mirror in a constitution in which a plurality of divided waveguides are arranged, to improve the output efficiency of laser light; and to down-size an apparatus. <P>SOLUTION: The waveguide is made of a plurality of divided waveguides. The divided waveguides are arranged continuously and slantly in folded shapes with their ends made adjacent. A middle reflecting mirror to reflect the laser light is provided at the mutual connection position of the divided waveguides such that the optical axes thereof coincide. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a waveguide laser oscillation apparatus that uses a plurality of waveguides to excite gas molecules as a laser medium and oscillates laser light amplified with a predetermined laser gain.

  In the waveguide type laser oscillation device, for example, a mixed gas containing CO2 gas as a laser medium is sealed, a semi-transmission mirror is provided at one end of the waveguide having a length corresponding to the laser gain, and the other end is provided. A total reflection mirror is arranged in the unit, and the emitted light is excited by the applied electric field and resonated between the semi-transparent mirror and the reflection mirror to induce the laser light to be guided and emitted from the mixed gas molecules. A laser beam amplified with a laser gain corresponding to the length of the wave tube is oscillated. In this type of waveguide laser oscillation device, the laser gain is low, and the device itself is increased in size to obtain a desired output.

  In order to solve this drawback, for example, in the laser device shown in FIG. 2 of Patent Document 1 (however, the laser device shown in Patent Document 1 uses a waveguide as a discharge excitation chamber), gas as a laser medium is used. Are arranged in multiple stages in parallel, the semi-transparent mirror 22 is arranged on the output side of the first discharge excitation chamber 46a, and the end of the second discharge excitation chamber 46b is disposed. The total reflection mirror 23 is arranged on the side, and the end side of the first discharge excitation chamber 46 a located on the opposite side of the semi-transparent mirror 22 and the end side of the second discharge excitation chamber 46 b located on the opposite side of the total reflection mirror 23. The intermediate reflecting mirrors 29 and 28 are respectively arranged at an angle of 45 ° with respect to the optical axis, and the length of the discharge excitation chamber is shortened to reduce the size of the apparatus.

The laser device applies the high-frequency voltage between the electrodes arranged in the first and second discharge excitation chambers 46a and 46b to apply an electric field to excite the light emitted by exciting the mixed gas molecules. By resonating in the first and second discharge excitation chambers 46a and 46b by the semi-transparent mirror 22, the two intermediate reflecting mirrors 29 and 28, and the total reflecting mirror 23, the laser light is stimulated and emitted from the gas mixture molecules. Laser light amplified with a desired laser gain is configured to be output through a semi-transparent mirror.

In the laser apparatus described above, the discharge excitation chambers 46a and 46b having a short length are arranged in multiple stages to substantially increase the waveguide distance of the waveguide, thereby enabling amplification with a desired laser gain. However, considering the reflection loss due to the two intermediate half mirrors, the output efficiency of the laser beam was poor.

That is, for example, the laser beam transmittance of the half mirror is 8%, the laser beam reflectance of the intermediate mirror is 99.5 to 99.7%, and thus the reflection loss is 0.3 to 0.5%. When laser light is output after resonating once in the second discharge excitation chamber, the laser light passing through the semi-transparent mirror is 8%, whereas the reflection loss by the two intermediate reflectors is 2% at the maximum. Therefore, 1/4 of the output is lost by the intermediate reflecting mirror, and the output efficiency of the laser beam is extremely poor.

Therefore, in order to increase the output of laser light while taking into account the reflection loss of the intermediate reflector, it is necessary to lengthen each waveguide or increase the current applied to the electrodes using a large-capacity power supply. Therefore, the intended purpose of downsizing the device itself cannot be achieved. In particular, when the power source is increased in size, it is necessary to provide a large cooling fan in order to suppress the heat generation of the power source, which is an obstacle to downsizing the apparatus.
JP-A-11-68214

The problem to be solved is that, with respect to the ratio of the laser light that passes through the semi-transparent mirror, the reflection loss by the intermediate reflecting mirror is high and the output efficiency of the laser light is poor. From the above problems, in order to obtain a desired output, it is necessary to lengthen the waveguide to some extent and increase the capacity of the power source, and the intended purpose of downsizing the device itself cannot be achieved. It is in.

The present invention relates to a waveguide having a length corresponding to a predetermined laser gain and filled with a gas laser medium, an electrode for applying an electric field to the gas laser medium in the waveguide, and a waveguide. A semi-transparent mirror that reflects the laser beam propagating in the waveguide and transmits it at a predetermined ratio, and a total reflection mirror that is disposed on the terminal end side of the waveguide and totally reflects the propagating laser beam In a waveguide laser oscillation apparatus that resonates laser light propagating in a waveguide with a semi-transparent mirror and a total reflection mirror, amplifies the laser light with a predetermined laser gain, and outputs the amplified laser light, the waveguide has a plurality of divided waveguides. Each divided waveguide is arranged in a slanted manner so that one end is close to each other and is folded so that they are continuous with each other, and the optical axes of the divided waveguides coincide with each other An intermediate reflector that reflects the laser light is provided. To.

  The present invention can improve the output efficiency of laser light by reducing reflection loss due to a semi-transparent mirror, a reflecting mirror, and a total reflecting mirror in a configuration in which waveguides are arranged in multiple stages. Further, the device itself can be reduced in size.

In the present invention, the waveguide is a plurality of divided waveguides, and each of the divided waveguides is inclined and arranged in a folded shape with one end close to each other so as to be continuous with each other. The best mode is to provide an intermediate reflecting mirror that reflects the laser light so that the optical axes coincide with each other at the connection points.

The present invention will be described below with reference to the drawings showing embodiments.
1 and 2, in the housing 3 of the waveguide laser oscillation device 1, the two divided waveguides 5 and 7 are inclined at a required angle so that one end is close to the other. Place with. Each of the divided waveguides 5 and 7 is made of a gas-impermeable dielectric material such as alumina (AL2O3), tempered glass (SiO2 base material), devitrified glass (glass ceramic), metal oxide (BeO, TiO2, etc.). The material has a hollow portion in which a mixed gas containing CO2 as a laser medium is enclosed. The divided waveguides 5 and 7 may have a circular or rectangular cross-sectional shape.

  Now, in the case of oscillating laser light having a predetermined output with a length of a laser oscillation device constituted by one waveguide being 1000 mm, for example, in the divided waveguides 5 and 7 of this embodiment, Under the same laser beam output conditions, the length is about half of 550 mm. By the way, in the parallel two-stage divided waveguide type laser oscillation device, in order to oscillate laser light having the same output as the single-stage waveguide type laser oscillation device, the division waveguide length is set to It is necessary to set to about 620 mm.

  A mixed gas as a laser medium is sealed in a hollow portion of each of the divided waveguides 5 and 7 at a predetermined gas pressure. As a sealing mode of the mixed gas, a sealing mode, or a bypass channel is provided between the end portions and a circulation pump is provided in the bypass channel, and a circulating sealing mode is further connected to a replenishing tank at one end portion. Any of the embodiments in which the mixed gas can be replenished may be used.

In addition, a pair of RF electrodes 9 and 11 extending along the entire axial direction are provided on the outer circumferences of the divided waveguides 5 and 7 in an electrically insulated state. These RF electrodes 9 and 11 excite the mixed gas sealed by the applied high-frequency current to generate high-frequency plasma to emit light.

A semi-transparent mirror 13 is arranged on the output side (right side in the figure) of the divided waveguide 5 located in the upper side in the figure. The semi-transparent mirror 13 has a characteristic that allows a predetermined wavelength to be partially reflected (reflectance: about 92%), and thus transmitted at a rate of 8%, on the surface of a base material such as ZnSe.

Further, an intermediate reflecting mirror 15 is disposed on the left end side of each of the divided waveguides 5 and 7 that are close to each other. Further, a total reflection mirror 17 is disposed on the right end portion side of the divided waveguide 7 positioned below in the drawing. The intermediate reflecting mirror 15 and the total reflecting mirror 17 are coated with a reflecting film such as Au on the surface of a base material such as copper or silicon, and are totally reflected at a reflectance of 99.5 to 99.7%.

The intermediate reflecting mirror 15 is arranged so as to reflect at a predetermined reflection angle at which the optical axis in one divided waveguide 5 and the optical axis in the other divided waveguide 7 coincide. The total reflection mirror 17 is a plane mirror or a concave mirror and is disposed so as to totally reflect the incident light from the optical axis in the other divided waveguide 7 in a direction that coincides with the optical axis.

Next, the laser light amplification oscillation action and method by the waveguide laser oscillation device 1 will be described.
As shown in FIG. 1, a high frequency voltage is applied to the RF electrodes 9 and 11 of the divided waveguides 5 and 7 to excite the mixed gas enclosed therein by applying a high frequency electric field to emit spontaneously emitted light. Then, the spontaneous emission light is reflected by, for example, the reflecting surface of the semi-transparent mirror 13, propagates leftward in the drawing in the first stage divided waveguide 5, is reflected by the intermediate reflecting mirror 15, and is reflected in two stages. After entering the divided waveguide 7 of the eye and propagating toward the right side in the figure, it is totally reflected by the total reflection mirror 17 and resonated in the divided waveguides 5 and 7.

At that time, light of a specific wavelength is absorbed by gas mixture molecules excited to a high level by a high-frequency electric field, and the coherent laser light is guided and emitted to propagate through the divided waveguides 5 and 7. The light is amplified with a laser gain corresponding to the waveguide length of the divided waveguides 5 and 7. The laser light amplified with a predetermined laser gain is transmitted through the semi-transparent mirror 13 with a predetermined transmittance and output to the outside.

When each of the above-described divided waveguides 5 and 7 resonates, each of the divided waveguides 5 and 7 is configured to be continuous by one intermediate reflecting mirror 15.・ The reflection loss due to the intermediate reflector can be reduced by half compared to the conventional waveguide laser oscillation device in which 7 is connected by two intermediate reflectors. The wave tubes 5 and 7 can be used to efficiently output laser light having a predetermined output.

Now, for example, when a waveguide laser oscillation device having a single-stage configuration that outputs a laser beam having a predetermined output using a waveguide having a length of 1000 mm is used as a reference, two parallel stages arranged as shown in FIG. In a conventional waveguide laser oscillation device in which a plurality of divided waveguides are connected by two intermediate reflecting mirrors, the length of each divided waveguide is 625 mm, the length is 37.5%, In the waveguide laser oscillation device 1 of the present embodiment, the length of each of the divided waveguides 5 and 7 is set to 555 mm by using one intermediate reflecting mirror 15. Can be shortened by 44.5%.

As a result, it is possible to amplify to a predetermined laser output by using the short divided waveguides 5 and 7 without increasing the power supply capacity for supplying a high-frequency voltage to the RF electrodes 9 and 11. It can be downsized. In addition, since heat generation from the power source can be suppressed and there is no need to use a large cooling fan, the device itself can be reduced in cost and size.

In the above description, the waveguide laser oscillation device 1 using two divided waveguides has been described. However, three or more divided waveguides are used, which is one less than the number of divided waveguides. Each divided waveguide may be made continuous by using a number of intermediate reflectors. In addition, about the same member as the said description, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

That is, as shown in FIG. 4 (FIG. 4 shows an example in which three divided waveguides are used, but in the present invention, two or more divided waveguides may be used). In addition, the waveguide laser oscillation device 51 is configured by using three divided waveguides 53, 55, and 57, and an end portion on the opposite side to the output end of the divided waveguide 53 positioned above in the figure. In the state where the end portion of the second-stage divided waveguide 55 is close to the end, the end portion of the third-stage divided waveguide 57 is disposed at the other end portion of the second-stage divided waveguide 55 while being inclined. The parts are inclined and arranged close to each other.

The semi-transparent mirror 13 is disposed on the output side of the first-stage split waveguide 53. Further, the end of the first-stage split waveguide 53 and the end of the second-stage split waveguide 55, the end of the second-stage split waveguide 55, and the third-stage split waveguide 57 are adjacent to each other. Intermediate reflecting mirrors 59 and 61 are disposed at the end portions, and a total reflecting mirror 63 is disposed at the other end portion of the third-stage divided waveguide 57.

One intermediate reflecting mirror 59 is arranged so as to reflect at a predetermined reflection angle at which the optical axis in the first-stage divided waveguide 53 and the optical axis in the second-stage divided waveguide 55 coincide. . The other intermediate reflecting mirror 61 is arranged so as to reflect at a predetermined reflection angle at which the optical axis of the second-stage split waveguide 55 and the optical axis of the third-stage split waveguide 57 coincide. Is done. Further, the total reflection mirror 63 is disposed so as to totally reflect the incident light from the optical axis in the third-stage divided waveguide 57 in a direction coinciding with the optical axis.

In this waveguide laser oscillating device 51, it is possible to output laser light amplified in accordance with a desired laser gain using the divided waveguides 55, 55 and 57 having a short waveguide length. At that time, the number of intermediate reflecting mirrors in which the divided waveguides 53, 55, and 57 are continuous can be reduced as compared with the case where a plurality of divided waveguides are arranged in parallel, and the intermediate reflection is correspondingly reduced. The reflection loss due to the mirror can be reduced.

As a result, it is possible to efficiently output the predetermined output laser light amplified with a desired laser gain by reducing the reflection loss due to the intermediate reflectors 59 and 61. In addition, the short divided waveguides 53, 55 and 57 can be used. The apparatus can be miniaturized.

Similarly to the above, for example, a waveguide laser oscillation device shown in FIG. 5 is based on a waveguide laser oscillation device having a one-stage configuration that uses a waveguide having a length of 1000 mm to output laser light having a predetermined output. 51, the length of each of the divided waveguides 53, 55, and 57 can be shortened by 54.6% by setting the length to 454 mm.

Further, in the above description, a plurality of divided waveguides are arranged in multiple stages in a folded manner in the vertical direction shown in the figure, but a plurality of divided waveguides are arranged in multiple stages in a folded manner in the horizontal direction. The configuration may be a combination of a plurality of divided waveguides folded back and forth in multiple stages and a plurality of divided waveguides folded back and arranged in multiple stages in the horizontal direction. In this case, it is possible to reduce the size of the device by reducing the volume of the device while increasing the waveguide distance by using a large number of divided waveguides.

1 is a plan block diagram showing a waveguide laser oscillation device of an embodiment embodying the present invention. FIG. 2 is a vertical sectional view taken along line AA in FIG. 1. It is explanatory drawing which shows the comparative example of waveguide length. It is explanatory drawing which shows the example of a change of a waveguide laser oscillation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Waveguide laser oscillation apparatus 3 Housing 5 * 7 Split waveguide 9 * 11 RF electrode 13 Semi-transparent mirror 15 Intermediate mirror 17 Total reflection mirror

Claims (2)

A waveguide having a length corresponding to a predetermined laser gain and filled with a gas laser medium, an electrode for exciting the gas laser medium in the waveguide by applying an electric field, and an output side of the waveguide A semi-transparent mirror that is disposed and reflects laser light propagating in the waveguide and transmits at a predetermined rate; and a total reflection mirror that is disposed on the terminal end side of the waveguide and totally reflects the propagating laser light; In a waveguide laser oscillation device that amplifies and outputs laser light propagating in a waveguide by a predetermined laser gain by resonating with a semi-transparent mirror and a total reflection mirror,
The waveguide is a plurality of divided waveguides,
Each of the divided waveguides is arranged so as to be in a folded shape with one end close to each other so as to be continuous with each other, and the lasers are arranged so that the optical axes of the divided waveguides coincide with each other. A waveguide laser oscillation device provided with an intermediate reflecting mirror for reflecting light. The divided waveguide according to claim 1 is a waveguide made of a gas-impermeable dielectric material and having a hollow part filled with a laser medium gas inside and having a circular or rectangular cross section in the direction perpendicular to the axis. Tube laser oscillator.

Images