JPH05275793A - Laser glass and laser - Google Patents

Abstract

PURPOSE:To obtain a laser for visible and ultraviolet lights having a high output and a high efficiency by amplifying a second harmonic wave of a fundamental wave generated from an oscillator of a laser medium in which neodymium is active ions by a laser glass amplifier in which silica glass is doped with copper, and further condensing it by a lens. CONSTITUTION:An Nd:YAG is used as an oscillator 31, a KTP is used as an optical nonlinear element 32 to generate a second harmonic wave of a fundamental wave, and an obtained laser light of 532nm is amplified by a laser glass amplifier 33 in which a silica glass is doped with copper. Further, it is condensed by a lens 34 to obtain a laser output having an energy density of 1 GW/cm<2> or more. A quartz glass doped with bivalent copper has a central emitting wavelength of 535nm to become a laser medium for efficiently amplifying the second harmonic wave of the Nd:YAG. A thermal expansion of the laser glass is extremely small, and a repetition pulse operation can be performed at 10pps or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a doped quartz glass used as a laser medium and a laser device having a large energy output and an excellent condensing property. Such a laser device can be used for fine processing.

[0002]

2. Description of the Related Art In the case of an Nd: YAG laser, a xenon flash lamp or a GaAs semiconductor laser is used as an excitation light source for laser oscillation. Since it is extremely difficult to manufacture a large Nd: YAG homogeneous laser crystal,
The light-collecting property was poor and high output could not be obtained. In order to improve it, a method has been adopted in which a laser glass doped with neodymium is used as an amplifier for amplification. Although laser glass has a high threshold of oscillation, it has excellent homogeneity,
Since it is easy to increase the size, silicate glass and phosphate glass are commercially available and suitable for amplifiers. To get harmonics,
After amplifying the fundamental wave with a laser glass amplifier, wavelength conversion is performed using an optical nonlinear element.

Silicate glass and phosphoric acid glass have problems in water resistance, heat resistance and mechanical strength, and a method of amplifying them by using quartz glass doped with neodymium (JP-A-60-76933) as a laser medium is also proposed. ing. It has no thermal lens effect, good light condensing properties, and high reliability.

[0004]

However, the above-mentioned conventional technique is an apparatus for amplifying the fundamental wave, and when the higher harmonic wave is used at the output, it has a poor conversion efficiency. In order to use it for fine processing and for processing transparent materials, a short-wavelength laser device is more advantageous, and it is unavoidable to use an excimer laser which is expensive and difficult to maintain. Since there is no laser medium capable of amplifying the second harmonic of Nd: YAG, there is a problem that a high output and efficient visible and ultraviolet laser device cannot be provided.

The present invention is intended to solve the above problems, and an object thereof is to provide a laser glass in which neodymium has a wavelength of the second harmonic of the laser medium of active ions. Another object is to provide a high-power and efficient visible and ultraviolet laser device.

[0006]

The above object is achieved by doping silica glass with copper. Also, a laser device using a laser glass in which silica glass is doped with copper as an oscillator. In a laser device in which the neodymium is a laser medium of active ions as an oscillator,
A laser device that amplifies the second harmonic of the fundamental wave with a laser glass amplifier in which silica glass is doped with copper. This is further achieved by providing a laser device that produces its harmonics.

[0007]

Example 1 Copper nitrate was added to and dissolved in a sol obtained by hydrolyzing ethyl silicate with an aqueous hydrochloric acid solution, and colloidal silica having an average particle size of 0.2 micron was further mixed. The amount of copper added to silica can be selected as an appropriate value, but here it was 0.1% by weight. Diluted aqueous solution of ammonia is gradually added to the sol, the pH of the sol is adjusted to 3 to 6 to cause gelation in a hydrophobic container such as polyfluoroethylene, and the lid is closed with an appropriate opening ratio. 40 ° C to 90
It was dried at a temperature of ° C to obtain a dry gel. Upon heating to a temperature of 1100 ° C. to 1300 ° C. with a suitable heating program, a yellowish transparent doped quartz glass was obtained.

Copper was doped in a divalent state, and when the fluorescence characteristics of the obtained glass were measured, it was 230 to 32.
It absorbed 0 nm ultraviolet light and emitted light in a wide wavelength range of 470 to 620 nm. FIG. 1 shows an emission spectrum of quartz glass doped with divalent copper. In addition, FIG. 2 shows an excitation spectrum of divalent copper-doped quartz glass. It was confirmed that the quartz glass doped with divalent copper has an emission center at 535 nm and is a laser medium capable of efficiently amplifying the second harmonic of Nd: YAG. From the excitation wavelength range, it was found that the glass base material needs to be quartz glass.

[0009] Copper-doped quartz glass is processed into a rod shape, and a resonator is constituted by a mirror having an appropriate reflectance.
When excited by the r excimer laser, laser oscillation occurred and the oscillation wavelength was variable in the range of 500 to 850 nm. Further, even if the laser was oscillated for a long time, the quartz glass rod doped with copper did not deteriorate due to solarization, and no change was observed in the laser characteristics.

Example 2 Cupric chloride was added to and dissolved in a sol obtained by hydrolyzing methyl silicate with an aqueous nitric acid solution, and colloidal silica having an average particle size of 0.15 micron was further mixed. Although an appropriate amount of copper can be selected, it is set to 0.05% by weight here. A diluted aqueous solution of ammonia was gradually added to the sol, the pH of the sol was adjusted to 4 to 6, and gelation was carried out in a hydrophobic container such as a cylindrical polypropylene. Transfer the gel to a container with an appropriate opening ratio, and
A tubular dry gel was obtained by drying at a temperature of 0 ° C to 90 ° C. 1100 ° C to 1300 ° C with appropriate heating program
When heated to a temperature of 1, a transparent doped quartz glass tube was obtained.

A quartz glass rod doped with copper was surrounded by a quartz glass tube, and cooling water was supplied. Several xenon flash lamps were placed around it, and a condenser mirror was installed to assemble a glass laser amplifier. A layout of the basic elements of a laser device using this amplifier is shown in FIG. If necessary, a Q switch, a Pockels cell, a Faraday rotator, a spatial filter, etc. may be arranged.

Nd: YAG is used for the oscillator 31 and KTP is used for the optical nonlinear element 32 to generate the second harmonic of the fundamental wave, and the obtained 532 nm laser light is doped with silica glass with copper. Laser glass amplifier 3
Amplified at 3. Further, the light is condensed by the lens 34 and 1 giga W /
A laser output with an energy density of cm ² or more was obtained. Since the thermal expansion of the laser glass is extremely small, the repeated pulse operation could be 10 pps or more. In addition, no deterioration due to solarization occurred and no change was observed in the laser characteristics even after excitation with a xenon flash lamp for a long time.

Example 3 Colloidal silica having an average particle size of 0.3 micron was mixed with a sol obtained by hydrolyzing ethyl silicate with an aqueous hydrochloric acid solution. A diluted aqueous solution of ammonia was gradually added to the sol, and the pH of the sol was adjusted to 4 to 6 to cause gelation. A plate-shaped dry gel was obtained by drying at a temperature of 40 ° C. to 90 ° C. in a container having an appropriate opening ratio. When heated to a temperature of 700 ° C. to 1000 ° C. with an appropriate heating program, a porous silica glass precursor having a proper strength was obtained. 0.5% by weight of copper nitrate in ethanol
It was melted, dipped in the quartz glass precursor, and sufficiently diffused. The surface was washed with ethanol and then heated to a temperature of 1100 ° C. to 1300 ° C. by an appropriate heating program to obtain a transparent doped quartz glass plate. 17 more
It was heated to 00 ° C. to extinguish the scattering source remaining in the glass. The light emission characteristics were the same as in Example 1.

A quartz glass plate doped with copper was placed at Brewster's angle and filled with nitrogen gas. Several xenon flash lamps were placed around it, a reflector was installed, and a glass laser amplifier was assembled. A layout of the basic elements of a laser device using this amplifier is shown in FIG. If necessary, a Q switch, a Pockels cell, a Faraday rotator, a spatial filter, etc. may be arranged. Also, a plurality of amplifiers may be used.

Semiconductor laser-excited Nd: YVO ₄ was used as an oscillator, and KTP was used as an optical nonlinear element to generate a second harmonic of the fundamental wave, and the obtained 532 nm laser light was doped into silica glass with copper. It was amplified with a laser glass amplifier that is already used. Next, add B to the optical nonlinear element 41.
Using BO, the second harmonic of the amplified laser light is generated, and the obtained 266 nm laser light is further focused by a lens to obtain a laser output with an energy density of 100 MW / cm ² or more. It was Since the thermal expansion of the laser glass is extremely small, the repeated pulse operation could be 10 pps or more. In addition, no deterioration due to solarization occurred and no change was observed in the laser characteristics even after excitation with a xenon flash lamp for a long time.

Although the embodiments have been described with respect to several kinds of laser devices, the arrangement of the excitation light source and the laser device is not limited at all. In addition, various doping concentrations of copper to the quartz glass and manufacturing methods can be considered.

[0017]

As described above, according to the present invention, by doping copper into silica glass, a laser glass in which neodymium matches the wavelength of the second harmonic of the laser medium of active ions can be achieved. Since it has the properties of quartz glass, it is chemically and thermally stable and can be widely applied as an optical component.

A laser device using a laser glass in which silica glass is doped with copper as an oscillator.
Neodymium is a laser device that uses a laser medium of active ions as an oscillator, and a laser device that amplifies the second harmonic of the fundamental wave with a laser glass amplifier in which silica glass is doped with copper. Furthermore, by providing a laser device for generating the higher harmonics, a high output and efficient visible and ultraviolet laser device can be achieved. For fine processing,
Furthermore, it can be applied to laser fusion.

[Brief description of drawings]

FIG. 1 is an emission spectrum diagram of quartz glass doped with copper of the present invention.

FIG. 2 is an excitation spectrum diagram of copper-doped silica glass of the present invention.

FIG. 3 is a layout diagram of a laser device according to a second embodiment of the present invention.

FIG. 4 is a layout view of a laser device according to a third embodiment of the present invention.

[Explanation of symbols]

 11 ... Emission spectrum of copper-doped silica glass 21 ... Excitation spectrum of copper-doped silica glass 31 ... Oscillator 32 ... Optical non-linear element 33 ... Laser glass amplifier 34 ... Condensing lens 41 ... Optical Non-linear element

Claims (4)

[Claims] 1. A laser glass, characterized in that silica glass is doped with copper. 2. A laser device characterized by using a laser glass in which silica glass is doped with copper for an oscillator. 3. A laser device using a laser medium of neodymium as an active material as an oscillator, wherein the second harmonic of the fundamental wave is amplified by a laser glass amplifier in which silica glass is doped with copper. .. 4. In a laser device using a laser medium of neodymium as an active ion as an oscillator, the second harmonic of the fundamental wave is amplified by a laser glass amplifier in which silica glass is doped with copper, and the higher harmonic is generated. A laser device characterized by: