KR0154423B1 - A laser glass - Google Patents

Abstract

The present invention formula 53ZrF ₄ -25BaF ₂ - relates to a laser glass that emits green and red consisting of _{(2-x) LaF 3 -3AlF} 3 -15NaF-2ErF 3 -xTmF 3.

The laser glass of the present invention has a very good property of improving green and red emission efficiency by 2 times and 500 times or more, respectively.

Description

Laser glass emitting green and red

1 shows energy diagrams of Er ³⁺ ions and Tm ³⁺ ions and the green and red fluorescence emission mechanism.

2 is a graph showing the intensity of green and red fluorescence according to TmF ₃ concentration in the laser glass of the present invention.

The present invention relates to a laser glass that emits green and red, which consist of the following formula.

_{53ZrF 4 -25BaF 2 - (2-} x) LaF 3 -3AlF 3 -15NaF-2ErF 3 -xTmF 3

In the above formula, x is 0 ≦ x ≦ 2 and the total content of LaF _{3 ,} ErF ₃ and TmF ₃ is 4 mol%.

There is a growing interest in blue or blue-green lasers for improved information storage densities and for communications between satellites and submarines. A mechanism for obtaining short wavelengths using long wavelengths includes second harmonic generation and frequency upconversion. The second harmonic generation uses the birefringence of the crystal, and the frequency upconversion uses the electronic structure of the atom, especially the rare earth ions.

Rare earth ions exhibit a unique spectrum because the optical transition of 4f ⁿ cores in the electronic structure is not affected by external influences. As a result, rare earth ions added to the single crystal have a narrow line width spectrum. However, important phenomena such as sensitization or fluorescence quenching are caused by the action of rare earth ions. These sensitization and attenuation actions are the action of two ions in the excited state and the ground state.

The long wavelength laser light is absorbed by the rare earth ions dispersed in the laser medium, and the interaction between the rare earth ions emits a wavelength shorter than the wavelength of the absorbed laser light. This phenomenon is frequency upconversion. The efficiency of light emitted is related to the type and concentration of rare earth ions.

Er for fluorozirco aluminate glasses in which yttrium, erbium and tulium compounds are present in rare earth ions³⁺Ions and Tm³⁺A study of emitting green and red colors using energy transfer between ions and frequency upconversion has been reported (X. Zou et al, J. Non-Cryst. Solids, vol 181, 100-106, 1995). Wherein this fluorozirco aluminate glass has a composition of 25 AlF.₃-13ZrF₄-(11-x-y) YF₃-46 (MgF₂+ CaF₂+ SrF₂+ BaF₂) -5NaF-xErF₃-yTmF₃Or Er emitting green fluorescence³⁺Ionic⁴S_3/2→⁴I_15/2Metastasis⁴I_13/2→⁴I_15/2(Er): 3H₆→³H₄(Tm) It has been reported that green fluorescence efficiency is greatly reduced by mutual relaxation. That is, energy is transferred from erbium to tulium to reduce the green fluorescence emission efficiency of the erbium ions.

In general, the network former forming the basic structure of glass has different polyhedrons of the network structure depending on the valence of the constituent compounds, and thus the glass's phonon distribution is different. Different oscillator distributions affect the emission efficiency of green fluorescence. In other words, the energy transfer relation by ⁴ I _13/2 → ⁴ I _15/2 (Er): ³ H ₆ → ³ H ₄ (Tm) mutual relaxation is due to the matrix glass composition to which rare earth ions are added. get affected. That is, the former fluorozirco aluminate glass is composed of alkaline earth compound (MgF ₂ + CaF ₂ + SrF ₂ + BaF ₂ ) which is a divalent metal, and these Group 2 metal compounds form a mesh structure of glass. As a result, the vibrator distribution of the glass is reduced and the above-mentioned mutual relaxation occurs to reduce the emission efficiency of the green fluorescence.

In the present invention, ZrF ₄ , a tetravalent metal compound, is used as the metal compound forming the basic structure of glass, and thus the vibrator distribution of the glass is large, thereby allowing energy to be transferred from tulium to erbium, thereby increasing green and red light emission efficiency.

It is an object of the present invention to provide a laser glass that emits green and red, which consist of the following composition.

_{53ZrF 4 -25BaF 2 - (2-} x) LaF 3 -3AlF 3 -15NaF-2ErF 3 -xTmF 3

In the above formula, x is 0 ≦ x ≦ 2 and the total content of LaF _{3 ,} ErF ₃ and TmF ₃ is 4 mol%.

Hereinafter, the laser glass of the present invention will be described in more detail.

The total content of LaF _{3 ,} ErF ₃ and TmF ₃ in the glass composition of the present invention is 4 mol%. When the value is larger or smaller than this value, the crystallization temperature and crystallization rate of the laser glass are increased, and the viscosity change with respect to the temperature is rapidly increased, resulting in poor applicability as the laser glass.

The laser glass of the present invention has an extremely good property in which energy is transferred from the Tm ³⁺ ion to the Er ³⁺ ion by the frequency up-conversion principle and the green and red efficiency is more than 2 times and the red efficiency is more than 500 times.

The principle of frequency upconversion and the emission efficiency increasing mechanism are shown in FIG.

As shown in FIG. 1, when the ⁴ I _9/2 level of Er ³⁺ ion having excellent green fluorescence efficiency is pumped with a wavelength 800 nm laser, the ⁴ I _13/2 level is set to ⁴ S as an intermediate level. Pumped to _3/2 level. When this energy transitions directly to the ground level, it emits green fluorescence at 530 nanometers and 550 nanometers, nonradiatively attenuates to the ⁴ F _9/2 level and then transitions to the ground level at 660 nanometers. Red fluorescence is emitted. These two rays are due to frequency up-conversion, which absorbs 800 nm laser light, which is infrared, in two stages, and emits light that is shorter in wavelength than the absorbed light.

The Sal 800-nm laser beams is not only absorbed by the Er ³⁺ ions Tm ³⁺ ions, so to absorb the beams emitted by the ³ F ₄ → ³ H ₄ transition of the Tm ³⁺ ions are transferred to the Er ³⁺ ions 530 nanometers emit electrons from the ² H _11/2 level to the base level by _increasing the electron density of the ⁴ S _3/2 level of Er ³⁺ ions emitting green light and the ⁴ F _9/2 level emitting red light meters will be green fluorescent and ⁴ S _3/2 550-nm green fluorescence efficiency and ⁴ F _9/2 of the red fluorescence efficiency of 660 nanometers, which transitions from the ground level to the level of release to the ground level at the level increases.

This frequency up-conversion efficiency may be measured as follows.

A laser beam of about 800 nanometers wavelength is focused with an objective lens (x10) to irradiate the specimen to excite the state of energy of the rare earth element. At this time, the excited electrons transition to the ground level and emit another light. The fluorescence of the specimen is focused on a spectrometer (monochromater). A photomultiplier is used as a photodetector in the visible region at the output of the spectroscope. Amplify the electrical signal from the photodetector, save the output to a computer, graph it, and compare the efficiency.

The method of manufacturing the laser glass of the present invention will be described as an example.

First, each raw material powder is weighed with an electric balance by varying the proportion of TmF ₃ to 2 mol% to calculate the weight percentage of each component for the selected glass composition as a batch weight of 20 g. The raw material used is an anhydrous fluoride compound having a purity of 99.9%. After washing the platinum crucible with aqueous hydrochloric acid, nitric acid and boric acid solution, washing it with distilled water and drying it, add the raw powder to the platinum crucible, add NH ₄ FHF about 5% of the weight of the raw material, and mix and grind it in the hood. do.

NH ₄ F.HF is added to prevent the raw material from reacting with oxygen in the air to form an oxide during the manufacturing process.

The mixed raw materials are covered with a platinum crucible lid and placed in an electric furnace to raise the temperature. The temperature in the furnace is controlled by a programmable temperature controller. An Al ₂ O ₃ tube is used to cover the vertical furnace and introduce N ₂ gas, the nitrogen flow rate is 2 lpm, and the purity of nitrogen is 99.99%. It is heated from room temperature to 400 ° C. at an elevated temperature rate of 400 ° C. per hour, and maintained at 400 ° C. for about 1 hour.

This is to react the oxide which may be contained in the raw material with a fluoride compound. If the oxide remains in the raw material, the oxide acts as a crystal nucleus during the vitrification process, and the glass crystallizes overall to become milky or opaque material, or remains as small fine crystals and becomes a scattering center, causing a large light loss of the glass. Becomes

Subsequently, the glass melt liquid heated to a nitrogen atmosphere at 800 ° C. for about 1 hour to be melted was adjusted for 15 minutes by controlling the atmosphere of the electric furnace with 2% CCl ₄ gas to remove OH ⁻ groups dissolved in the glass.

The OH ⁻ group causes light absorption near 3400 cm ⁻¹ and the reactive gas atmosphere process reaction conducted in CCl ₄ atmosphere is a process for removing the OH ⁻ group.

The molten glass is poured into a brass mold preheated to a temperature slightly lower than the glass's vitrification temperature (270 ° C) and quenched to form a cylindrical rod, held at the vitrification temperature for about 2 hours to remove stress caused during the cooling process and to room temperature. Cool down to.

On the other hand, in order to measure the optical characteristics, the specimen of the glass rod 10 mm in diameter manufactured as described above was cut using a 2 mm thick low speed diamond rotary saw and then polished on both sides so that the wide sides were parallel to each other. On both sides of the polished wide surface, the two surfaces are polished to be vertical. The polished specimens are washed with methanol and distilled water.

The green and red fluorescence intensities of the laser glass with the concentration of Tm ³⁺ ions are measured by the previously presented method. The results are shown in FIG.

In FIG. 2, the glass having 0 mol of TmF ₃ has a composition of 53 ZrF ₄ -25BaF ₂ -2LaF ₃ -3AlF ₃ -15NaF-2ErF ₃ . Compared to the laser glass of this composition, the green fluorescence of 530 and 550 nanometers increased by 2 times at 0.5 moles and 660 nanometers at 1.0 moles by 500 times as the substitution of TmF ₃ instead of LaF ₃ of this glass. .

Claims (1)

The laser glass that emits green and red consisting of a composition of food: 53ZrF ₄ -25BaF ₂ - and _{(2-x) LaF 3 -3AlF} 3 -15NaF-2ErF 3 -xTmF 3 wherein x is 0≤x≤2, The total content of LaF _3, ErF ₃ and TmF ₃ is 4 mol%.