JPH08208265A - Infrared-visible converting material - Google Patents

Abstract

PURPOSE: To obtain an infrared-visible converting material capable of converting infrared rays of an Nd : yttrium aluminum garnet (Nd:YAG) laser or an Nd : yttrium lithium fluoride (Nd:YLF) laser into visible radiation. CONSTITUTION: This infrared-visible converting material is a microspherical glass comprising a halide glass such as a fluoride glass or a chloride glass or a mixed halide glass such as a chlorofluoride glass containing at least one of Er, Ha, Pr, Tm, Gd and Dy as rare earth ions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visible light source used in the fields of optical memories, display light sources, medical care, optical measurement and optical information processing, and in particular 1.064 .mu.m which is the fundamental wave of Nd: YAG laser. And an infrared-visible conversion material for converting infrared light of 1.054 μm, which is a fundamental wave of an Nd: YLF laser, into visible light.

[0002]

2. Description of the Related Art In recent years, various visible light lasers have been developed in order to shorten the wavelength of light in order to enable high density optical discs and high sensitivity photodetection. Gas lasers and semiconductor lasers are known as lasers that can directly obtain visible light, but the gas lasers are large and have a short life. Semiconductor lasers are currently on the market III
It is difficult to obtain light having a wavelength shorter than red with a group-V semiconductor compound due to material restrictions, and a blue laser made of a group IV-VI semiconductor compound has a remarkably short life, and more time is required for practical use. On the other hand, as a method of obtaining visible light by converting the wavelength of infrared laser light, Nd: YAG 1.064 μm
In which harmonic light is converted by using a second-order nonlinear optical material (anisotropic single crystal) such as KTiOPO _4, or in a bulk-shaped fluoride single crystal or fluoride glass to which a specific rare earth element is added, Upconversion (frequency up-conversion) emission is known, which excites an absorption wavelength of a rare earth element existing in the infrared region and converts infrared light into visible light.

[0003]

However, in the method of performing infrared-visible conversion using a nonlinear optical material, it is necessary to satisfy the phase matching condition, so that the crystal is cut or the optical system is complicated, and the nonlinear optical system is used. There is a problem that the optical crystal itself is expensive. In addition, in the infrared-visible conversion by the up-conversion mechanism in bulk-shaped fluoride crystals and glasses to which rare earth elements have been added, energy transfer between excited ions between the intermediate levels of various rare earth elements and absorption of excited states in multiple stages It is known that infrared light can be converted into visible light by excitation, but Nd: YA
1.064 μm which is the fundamental wave of G laser and Nd: YL
Since there is no rare earth element having an absorption peak wavelength that matches the fundamental wavelength of 1.054 μm, which is the fundamental wave of F laser, only the fundamental wave of Nd: YAG laser or Nd: YLF laser is used and the visible light is emitted by the up-conversion mechanism. Obtaining a laser has traditionally been difficult. However, Nd: YAG laser or Nd: YLF
Since the laser has a high degree of perfection as a solid-state laser, and is relatively compact and can easily achieve high output, it requires a complicated optical system such as when using these lasers as an excitation light source and a nonlinear optical material. It is desired to develop a visible light laser by infrared-visible conversion.

[0004]

The infrared-visible conversion material of the present invention for solving the above-mentioned problems is 1.064 μm which is the fundamental wave of Nd: YAG laser and 1.054 μm which is the fundamental wave of Nd: YLF laser. Is a material that converts infrared light into visible light, and is microsphere glass containing a rare earth element.

The infrared-visible conversion material of the present invention can be applied to a halide glass such as a fluoride glass or a chloride glass having a small phonon energy and a small multiphonon relaxation rate, or a mixed halide glass such as a chlorine fluoride glass.
Er, Ho, Pr, Tm, Gd and D as active ions
Among y, at least one glass material added,
By making a microsphere shape by the method described in Japanese Patent Application No. 5-190392 or by polishing or the like, it becomes possible to efficiently confine light energy inside the microsphere at a high density, and it has been conventionally reported in the bulk shape or the fiber shape. Due to the up-conversion mechanism centered on simultaneous multiphoton simultaneous absorption, it is the fundamental wave of an Nd: YAG laser at room temperature, despite the absence of excitation levels of rare earth elements.
The fundamental wave of the 064 μm and Nd: YLF laser is 1.
It converts light of 054 μm into visible light. In the present invention, when Tm and Pr are added as rare earth ions, blue light emission can be obtained, and Er, Ho and D can be obtained.
When y is added, green light emission can be efficiently obtained.

The microsphere glass material is AlF which does not contain alkali ions in consideration of chemical durability and mechanical strength.
Fluoride glasses of ₃ series, InF ₃ series and ZrF ₄ series are preferred, and glass having a small lattice phonon energy is preferred because it is necessary to reduce non-radiative transition loss in consideration of conversion efficiency.

[0007]

Function: A fluoride glass or a chloride glass such as a chloride glass or a mixed halide glass such as a chlorine fluoride glass, which has a low phonon energy and a low multiphonon relaxation rate, is mixed with Er, Ho, Pr, or
By making glass containing at least one of Tm, Gd and Dy into a microsphere shape, it becomes possible to efficiently confine light energy inside the microsphere with high density. Due to an up-conversion mechanism centered on multiphoton simultaneous absorption, which has not been reported, the fundamental wave of the Nd: YAG laser at 1.064 μm and Nd: YLF is detected at room temperature in spite of the absence of excitation levels of rare earth elements. It is possible to convert the light of the fundamental wave of the laser, 1.054 μm, into visible light without using a complicated optical system.

[0008]

Embodiments of the present invention will be specifically described below with reference to the drawings, but the present invention is not limited to these embodiments.

Example 1 FIG. 1 shows a case where Nd: YAG is used for the infrared-visible conversion material of the present invention.
1 is an embodiment of a system for converting a laser light of 1.064 μm, which is a fundamental wave of a laser, into visible light. In the figure, reference numeral 1 is an Nd: YAG laser, 2 is a dichroic mirror, 3 is an objective lens, and 4 is an objective lens. Multi-channel spectrophotometer, 5 CCD camera, 6 monitor, 7
Is an XYZ stage, 8 is a lens, and A is an infrared-visible conversion material. Infrared - visible light conversion material, 45InF ₃ -30
PbF ₂ -25ZnF ₂ (mol%) fluoride glass was added with 1 mol% Er ³⁺ to form microspheres having a diameter of 100 μm. The glass microspheres are disclosed in Japanese Patent Application No. 5-190392.
It was prepared according to the method described in No. Using this system,
When the condensed Nd: YAG laser was made incident on the infrared-visible conversion material, a green emission spectrum shown in FIG. 2 was obtained. Further, by scanning the XYZ stage while observing the monitor, Nd internal microsphere so that light circulates: was adjusted the irradiation position of the YAG laser, ⁴
Confirmed apparently sharp plurality of spectrum than fluorescent you think that the laser oscillation wavelength of 550nm near equivalent to S _3/2 → ⁴ I _15/2 transition.

Example 2 As an infrared-visible conversion material, 65ZrF ₄ -35BaF
An Nd: YAG laser was infrared-visible in the same system as in Example 1 except that glass microspheres having a diameter of 50 μm were ^prepared by adding 0.1% Tm ³⁺ to ₂ (mol%) fluoride glass. When the light was made incident on the conversion material, a blue emission spectrum shown in FIG. 3 and a plurality of sharp spectra considered to be laser oscillation were confirmed at a wavelength near 460 nm corresponding to the ¹ D ₂ → ³ H ₄ transition.

Embodiment 3 Instead of the Nd: YAG laser, Nd: YLF (1.05)
As a result of performing the same operation as in Example 1 except that (4 μm) was used, an emission spectrum similar to that in Example 1 was obtained.

Example 4 AgBr-PbBr bromide glass was used as the infrared-visible conversion material, and Ho ³⁺ or Dy ³⁺ was used as the active ions.
As a result of performing the same operation as in Example 1 except that glass microspheres added with are used, the emission spectra shown in FIGS. 4 and 5 are obtained for Ho ³⁺ or Dy ³⁺ , respectively.
A plurality of sharp spectra, which are considered to be laser oscillations, were confirmed around 550 nm for Ho ³⁺ and around 540 nm for Dy ³⁺ .

[0013]

As described above, fluoride glass having a small phonon energy and a small multiphonon relaxation rate, a halide glass such as a chloride glass or a mixed halide glass such as a chlorine fluoride glass has Er as an active ion. , Ho, Pr, Tm, Gd, and Dy are made into a microsphere shape by adding at least one of them to form a microsphere, and the fundamental wave of the Nd: YAG laser is 1.064 μm and Nd: YLF laser at room temperature. The fundamental wave of 1.054 μm light can be converted into visible light.

[Brief description of drawings]

FIG. 1 schematically shows a system for converting laser light into visible light by using an infrared-visible conversion material.

FIG. 2 shows an emission spectrum when the glass microspheres (Er ³⁺ added) shown in Example 1 were used.

FIG. 3 shows an emission spectrum when the glass microspheres (added with Tm ³⁺ ) shown in Example 2 were used.

FIG. 4 shows an emission spectrum when the glass microspheres (with Ho ³⁺ added) shown in Example 4 were used.

FIG. 5 shows an emission spectrum when the glass microspheres (added with Dy ³⁺ ) shown in Example 4 were used.

[Explanation of symbols]

 1. Nd: YAG laser 2. Dichroic mirror 3. Objective lens 4. Multi-channel spectrophotometer 5. CCD camera 6. Monitor 7. XYZ stage 8. Lens A. Infrared-visible conversion material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Masuhara 2-4-16 Minamikonoike-cho, Higashi-Osaka-shi, Osaka (72) Inventor Keiji Sasaki 4-6-8 Nyoya, Minoh-shi, Osaka

Claims (3)

[Claims] 1. A fundamental wave of an Nd: YAG laser.
An infrared-visible conversion material that is a material that converts infrared light of 054 μm or 1.054 μm, which is the fundamental wave of an Nd: YLF laser, into visible light, and is microsphere glass containing a rare earth element. 2. Er, Ho, Pr, as rare earth ions,
The infrared-visible conversion material according to claim 1, comprising at least one of Tm, Gd, and Dy. 3. The infrared-visible conversion material according to claim 1, wherein the microsphere glass is a halide glass such as fluoride glass or chloride glass or a mixed halide glass such as chlorine fluoride glass. .