JPH10273337A - Glass material for wavelength transformation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a glass material useful e.g. as a fluorescent substance for display units, capable of such transformation of a wavelength into a shorter one using red to infrared rays as exciting light as to remain impossible for conventional wavelength transformation glass materials by incorporating cadmium-based chloride glass with neodymium ions as luminescent ions in specific proportions based on the whole cations. SOLUTION: This glass material is obtained by incorporating a cadmium- based glass material (e.g. a glass material obtained from anhydrous cadmium chloride, anhydrous barium chloride, anhydrous strontium chloride, sodium chloride and potassium chloride), if necessary, prepared by substituting part of cadmium with alkali metal or alkaline earth metal, with neodymium ions as luminescent ions at 0.1 to 2.0 mol.% (0.1 to 2.0 mol% in terms of NdCl2 ), pref. 0.5 to 1.5 mol.% based upon the whole cations (100 mol.%). As a result, an ultraviolet to violet light having a shorter wavelength of <=450 nm is obtained by using an exciting light with 780 to 830 nm wavelength in a red to infrared band.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wavelength conversion material for converting red or infrared light having a wavelength of less than 730 to 830 nm from ultraviolet light having a wavelength of 350 to 440 nm into visible blue light. The wavelength conversion glass material of the present invention can be widely applied as a phosphor for a display, a blue-violet solid laser medium, and the like.

[0002]

2. Description of the Related Art In an optical recording medium such as a compact disk or a magneto-optical disk, a laser having a shorter wavelength is more advantageous for improving the recording density, and the wavelength of a semiconductor laser is being shortened. Further, attempts have been made to convert semiconductor laser light in the red to infrared region into a blue to green laser having a shorter wavelength by using an up-conversion phosphor.

[0003] As this kind of up-conversion phosphor, there are known a large number of phosphors having a base material of fluoride having a low binding energy and doped with rare earth fluorescent ions. For example, from a single crystal phosphor containing neodymium ion in lanthanum fluoride, two wavelengths of 788 nm and 591 nm are used.
A 380-nm purple laser beam is obtained by wavelength excitation (Appl Phys. Lett., 52, 16, 1300-1302, 1988). However, the crystal has difficulty in workability, it is difficult to form into a fiber or the like, and it is also difficult to obtain a large single crystal. In addition, the crystal has a high ligand field symmetry, so the emission transition probability is low, and the absorption width is narrow, so that the excitation efficiency varies when pumping with a laser, such as a semiconductor laser, where the wavelength of the excitation light tends to fluctuate. Is large.

For this reason, vitreous phosphors have been studied. As for the transparent glass material used as the phosphor, it is easy to produce a material having less loss and scattering in the generation of visible light than crystals. Also, it is easy to mold into any form such as fiber. Further, the fluctuation of the absorption efficiency due to the fluctuation of the wavelength of the excitation light is small. For this reason, there is an advantage that a stable output can be obtained even when a semiconductor laser whose output wavelength tends to fluctuate due to the influence of temperature, current or the like is used as an excitation source.

[0005] As a glass material for converting red to infrared light into a short wavelength of green to blue, a glass material in which praseodymium (Pr) ions are doped into indium fluoride glass has been known. In this glass material, blue fluorescence of 480 nm was obtained by excitation of 588 nm (Phys. Rev. B50, 162).
19-16223, 1994). In addition, an example in which a green laser is oscillated at room temperature by a glass material in which zirconium fluoride-based glass is doped with holmium (Ho) ions (Electron.Let
t., 26.261-263, 1990). But,
These are red to red that can be obtained with widely used semiconductor lasers.
Excitation light in the infrared region, especially high-power one, can be easily obtained 7
It does not use excitation light of 80 to less than 830 nm.

There is also known a glass material which emits blue light by using an alkaline earth halide glass as a base material and containing Ho ions and Yb ions (Japanese Patent Application Laid-Open No. 6-219777). The material is 830-1000
The laser light of nm is used as the excitation light source, and the excitation light of 780 to less than 830 nm is not used similarly to the above-mentioned glass material.

[0007]

SUMMARY OF THE INVENTION The present invention provides a wavelength conversion glass material which can be converted into a short wavelength which cannot be obtained by a conventional wavelength conversion glass material. It is an object of the present invention to provide a wavelength conversion material capable of obtaining a short-wavelength laser beam of 450 nm or less by light.

[0008]

According to the present invention, (1) a cadmium-based chloride glass material contains 0.1 to 2 mol% of neodymium (Nd) ions as luminescent ions with respect to the whole cations. A wavelength conversion glass material characterized by the following is provided. The glass material of the present invention includes (2) a wavelength conversion glass using a cadmium chloride glass in which a part of cadmium is replaced by an alkali metal or an alkaline earth metal.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The wavelength conversion glass material of the present invention is cadmium (Cd) having a lower binding energy than fluoride glass.
By using neodymium (Nd) as a rare earth fluorescent ion using a base chloride glass as a glass base material,
The red-to-infrared light of 30 to 830 nm can be converted from ultraviolet light of 350 to 440 nm into visible blue light with high efficiency.

Cd-based chloride glass is a typical well-known chloride glass (Mat. Res. Bull. Vol. 18,
631-636, 1983, JP-A-60-246242). Since this glass has a lower phonon energy than conventional fluoride glass, it is expected as a base material for up-conversion phosphors, and erbium (Er) ions doped as luminescent active ions have been studied. (Appl.P
hys. Lett. 65 (15), 10 October 1994, Appl. Phys. Lett. 61
(22), 30 November 1992). However, a wavelength conversion glass material using a Cd-based chloride glass as a base material in which red to infrared light is converted into ultraviolet to blue light by doping with Nd ions is not known.

In the glass material of the present invention, the Cd-based chloride glass used as a base material is such that the main component of the cation forming the glass is Cd ion and the main component of the anion forming the glass is chlorine ion. Say something. The above Cd
The base chloride glass may be one in which part of cadmium is replaced by an alkali metal, an alkaline earth metal, or lead. By containing these, the stability of the glass base material can be increased. As an example, Ba: about 12 to 36
Mol%, Sr: about 2 to 26 mol%, K: about 5 to 20 mol%, N
a: about 2 to 4 mol%, Rb: about 5 to 12 mol%, Li: about 1
Examples containing about 2 mol% and about 2-14 mol% of lead are shown in Examples.

The wavelength conversion glass material of the present invention contains Nd ions as active ions involved in light emission. The content of Nd ions is 0.1 to 2.2 with respect to the whole cations (100 mol%).
0 mol% (0.1 to 2.0 mol% as Nd chloride) is appropriate.
If the Nd ion exceeds this range, the melt does not become uniform and a transparent glass body cannot be obtained. If the Nd ion content is less than this range, sufficient fluorescence from ultraviolet to blue (350 to 440 nm) cannot be obtained. A homogeneous transparent glass body can be easily manufactured,
The range of the Nd ion doping amount that can provide ultraviolet to blue (350 to 440 nm) fluorescence with sufficient intensity is 0.5 to 1.5 mol% (0.5 to 1.5 mol% as neodymium chloride). Note that Nd
It is not preferable to add other rare earth ions together with the ions, since the blue / purple fluorescence intensity decreases.

[0013]

EXAMPLES AND COMPARATIVE EXAMPLES Example 1 (A) Production of Glass Material Anhydrous neodymium chloride synthesized by a conventional method and well-dried anhydrous cadmium chloride, anhydrous barium chloride, anhydrous strontium chloride, sodium chloride and potassium chloride were prepared. The mixture prepared in the ratio of 1 was placed in a glassy carbon crucible and heated to 600 ° C. in an argon atmosphere to be completely melted. After the melting, the temperature was lowered to 450 ° C., and gasified carbon tetrachloride and carbon monoxide were blown into the melt for 2 hours to remove water. Subsequently, argon gas was
After supersaturated chlorine and the like were removed by blowing for a time, the melt was sucked into a quartz tube, cooled, solidified, and sealed in a vacuum. This was put into a furnace together with the quartz tube and re-melted, immediately cooled to the glass transition point, annealed at this temperature for 2 hours, and gradually cooled to obtain a transparent glass sample.

(B) Fluorescence Measurement The glass sample (No. 1 to No. 10) obtained in the above manufacturing process is cut into a predetermined length, and the surface is polished to form a columnar shape (length 5 mm, diameter 2.5 m).
m), and a pulse laser beam of 808 nm (pulse width 10 ns,
A beam diameter of 1 mm ² , ² mJ / pulse) was irradiated from one of the polished surfaces to measure up-conversion fluorescence. For each sample,
Table 1 shows the peak wavelength of the fluorescence at 808 nm excitation.
Gain was obtained at 388 nm and 417 nm for all samples. For sample No. 1, 300 to
FIG. 1 shows the fluorescence spectrum in the wavelength range of 680 nm. As shown in this spectrum diagram, the ultraviolet region (about 361
nm, 388 nm) and in the purple region (about 417 nm, 420 nm, 436 nm). In addition, almost the same fluorescence spectrum was obtained when the pulse laser beam of 750 nm was used.
Further, the transmission spectrum of Sample No. 1 in the wavelength range of 720 to 840 nm was measured, and this graph is shown in FIG. As shown in the figure, this sample glass has a large absorption area around about 750 nm and about 810 nm.
It can be seen that the maximum fluorescence intensity can be obtained by using infrared light of this wavelength as excitation light.

[0015]

[Table 1]

Example 2 A glass material having the following composition was produced in the same manner as in Example 1. _{(50-x) CdCl 2 ·} 22BaCl 2 · 8SrC
l ₂ · 10KCl · xNdCl ₃ Example 1
In the same manner as in the above, a laser beam of 808 nm was irradiated, and the fluorescence intensities at 436 nm and 436 nm with respect to mol% of Nd chloride were measured. The result is shown in FIG. The blue fluorescence at 436 nm shows the maximum intensity at about 0.5 mol% Nd chloride. On the other hand, the violet fluorescence at 388 nm has an increased fluorescence intensity in proportion to the concentration of Nd chloride. However, since the solid solution limit of Nd chloride is about 2 mol%, this is the upper limit of the fluorescence intensity. Note that 360
The fluorescence intensity around nm and 420 nm showed the same tendency as the above fluorescence at 388 nm.

[0017] Comparative Example ZBLAN glass _{(53ZrF 4 · 20BaF 2 · LaF} 3 · 3A1F 3 · 20NaF · 3Nd
A glass material containing about 3 mol% of Nd ions in F ₃ ) was prepared, and the fluorescence was measured in the same manner as in this example.
No fluorescence could be confirmed in the wavelength range of 440 nm.

[0018]

The wavelength conversion glass material of the present invention can use red to infrared light as excitation light to convert it into short wavelengths that cannot be obtained with conventional wavelength conversion glass materials. The external light can be converted to ultraviolet to purple short wavelength light of 450 nm or less.

[Brief description of the drawings]

FIG. 1 is a fluorescence spectrum diagram of Sample No. 1 shown in Table 1 at 300 to 680 nm.

FIG. 2 is a transmission spectrum diagram of Sample No. 1 shown in Table 1 at 720 to 840 nm.

FIG. 3 is a graph showing the fluorescence intensity of Example 2.

Claims (2)

[Claims] 1. A cadmium-based chloride glass material,
1. A wavelength conversion glass material comprising neodymium (Nd) ions as luminescent ions in an amount of 0.1 to 2 mol% based on the whole cations. 2. The wavelength conversion glass material according to claim 1, wherein a cadmium chloride glass in which part of cadmium is replaced by an alkali metal or an alkaline earth metal is used.