CN101457402A - Method for preparing erbium doped Na2Gd4(MoO4)7 laser crystal - Google Patents

Abstract

The invention relates to an erbium-doped tetragadolinium lithium heptamolybdate laser crystal and a preparation method thereof, relating to the field of artificial crystals. The pulling method is adopted, the growth temperature is 1080° C., the lifting speed is 0.5-2.0 mm/hour, and the crystal rotation speed is 10-30 revolutions/minute. Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ crystals with high optical quality and large size were grown. The crystal belongs to the tetragonal crystal system. Spectral analysis shows that the crystal has a broad absorption peak and a strong fluorescence emission peak. It is suitable for LD pumping and can be used as a laser crystal to produce laser output with a wavelength of about 550nm and 1500nm.

Description

Erbium-doped tetragadolinium lithium heptamolybdate laser crystal and preparation method thereof

technical field

The invention belongs to the field of artificial crystal and crystal growth in the technical field of optoelectronic functional materials, and in particular relates to a laser crystal material used as a working substance in a solid-state laser.

Background technique

Laser crystal is the working substance of solid-state laser. It refers to the luminescent material that uses crystal as the matrix to absorb pump light energy and convert it into laser output through discrete luminescent centers. The solid-state laser working substance is composed of matrix material and active ions. Its various physical and chemical properties are mainly determined by the matrix material, while its spectral characteristics and fluorescence lifetime are determined by the energy level structure of the active ion. Since the artificial ruby pulse laser was successfully developed in 1960, hundreds of laser crystals have been discovered so far, but due to various reasons, there are only a dozen kinds of laser crystals that can really be used in practice.

At present, the most widely used laser crystal is yttrium aluminum garnet (YAG) crystal doped with neodymium ions, which has good physical and chemical properties, and is easy to grow high-quality crystals with high optical quality and large size. But it has the disadvantage of narrow absorption spectrum, which is not suitable for pumping by LD, and LD pumping will be the development direction of laser pumping source in the future.

At present, both at home and abroad are actively looking for high-quality laser crystal materials with excellent physical, chemical and mechanical properties, easy to grow high optical quality, large size and suitable for LD pumping. As an important laser-activated ion, Er ³⁺ ions have abundant energy levels, and there are nine transition channels from visible to near-infrared emission wavelengths, among which the laser emission in the 1.5 μm and 3.0 μm bands corresponds to ⁴ I _13/2 The transition between → ⁴ I _15/2 and ⁴ I _11/2 → ⁴ I _15/2 energy levels. 1.5μm laser is safe for human eyes, and human cells and tissues strongly absorb 3.0μm laser. Laser crystals with Er ³⁺ ions as active ions have broad application prospects in communication and medical fields. Therefore, in recent years, erbium ions have become a popular choice for activating ions in laser crystals.

Contents of the invention

The purpose of the present invention is to develop a new laser crystal Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ , which can be directly pumped by flash lamp and LD, and has high conversion efficiency. Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ crystals belong to the tetragonal crystal system, in which erbium ions are used as dopant ions to replace the lattice positions of gadolinium ions. When the doping concentration of erbium is about 1 at.%, the fluorescence lifetime (T) is 4-5ms, and its fluorescence lifetime is a function of the concentration of erbium ions, and different concentrations of erbium ions can be added according to different needs. Experimental results show that it can output laser light with a wavelength of about 550nm and 1500nm, and it can be used as a laser crystal.

Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ crystal is a melting compound with the same composition, which is grown by the pulling method. According to the chemical reaction formula: Li ₂ CO ₃ +2Gd ₂ O ₃ +7MoO ₃ = =Li ₂ Gd ₄ (MoO ₄ ) ₇ +CO ₂ for weighing, mixing, tableting, and sintering, while Er ₂ O ₃ was added according to the required concentration.

The raw materials used are:

drug name purity factory Er ₂ O ₃ 99.999% Changchun Institute of Applied Chemistry, Chinese Academy of Sciences Gd ₂ O ₃ 99.999% Changchun Institute of Applied Chemistry, Chinese Academy of Sciences Li ₂ CO ₃ 99.99% Sinopharm Shanghai Chemical Reagent Co., Ltd. MoO ₃ 99.99% China National Pharmaceutical Group Shanghai Chemical Reagent Company

The main growth conditions are as follows: the growth is carried out in a platinum crucible under an oxygen-enriched atmosphere (air), the parameters of crystal growth are growth temperature 1080°C, the lifting speed is 0.5-2.0 mm/hour, and the crystal rotation speed is 10-30 rpm. Minutes, high-quality Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ crystals were grown.

D_c＝5.49g/cm³，该晶体中Er³⁺离子作为激光激活离子，其掺杂浓度在0.5at.-10at.％之间。The grown Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ crystal was collected on a powder diffractometer for diffraction data. The structural analysis showed that it belonged to the tetragonal crystal system, and the unit cell parameters were

D _c =5.49g/cm ³ , Er ³⁺ ions in the crystal are used as laser-activated ions, and the doping concentration thereof is between 0.5 at.-10 at.%.

The grown Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ crystal was analyzed and tested for polarized absorption spectrum, fluorescence spectrum and fluorescence lifetime. The results showed that: Er ³⁺ doped with 0.79at.% Er ³⁺ ions: The main absorption peak of Li ₂ Gd ₄ (MoO ₄ ) ₇ crystal is at 977nm, its half-peak width is 10.5nm, and the absorption transition cross section is 0.70×10 ^-20 cm ² , the large half-peak width at 977nm is very suitable for InGaAs semiconductor laser is used for pumping, which is beneficial to the absorption of pumping light by laser crystals and improves pumping efficiency. In addition, it has a strong fluorescence emission peak near the wavelength of 1500nm, the emission transition cross section of σ polarization at 1536nm is 1.10×10 ^-20 cm ² , the emission transition cross section of π polarization at 1536nm is 0.42×10 ^-20 cm ² , and the fluorescence lifetime It is 4.06ms, because the crystal with long fluorescence lifetime can accumulate more particles in the upper energy level, which increases the energy storage, which is beneficial to the improvement of the output power and output energy of the device. Therefore, Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ crystal can obtain higher power laser output, and it is a laser crystal with high conversion efficiency, low cost, high optical quality, practical application prospect and use value.

Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ crystals can be easily grown into high-quality crystals by the pulling method, and the growth rate is fast; the Vickers hardness of the crystal is 330VDH, the hardness is moderate, and it is easy to process; it has excellent optical properties Features: It is easy to use flash lamp pumping and LD pumping to obtain laser output, and the laser output wavelength is about 550nm and 1500nm. This crystal can be used as a better laser crystal.

Detailed ways

Realize the preferred mode of experiment of the present invention as follows:

Example: Growth of Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ laser crystal with a doping concentration of 0.79 at.% Er ³⁺ by pulling method.

Mix and grind Li ₂ CO ₃ , Gd ₂ O ₃ , MoO ₃ , and Er ₂ O ₃ that have been accurately weighed according to the ratio, and grind ^them evenly. Solid state reaction at 650°C for 24 hours; after taking it out, regrind the pressed tablet and raise the temperature to 850°C for 24 hours. Put the synthesized above samples into a Φ45×40mm ³ platinum crucible, adopt the pulling method, in the air atmosphere, the growth temperature is 1080°C, the crystal rotation speed is 20 rpm, and the pulling speed is 1 mm/hour. In this case, high-quality Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ crystals with a size of Φ20×25mm ³ were grown. The ICP test shows that the content of Er ³⁺ ions in the crystal is 0.79 at.%.

Claims (3)

1. a kind of erbium-doped tetragadolinium lithium heptamolybdate laser crystal is characterized in that: the molecular formula of this crystal is Er ³⁺ : Li ₂ Gd ₄ (MoO ₄ ) ₇ , belongs to tetragonal crystal system, and unit cell parameter is

D _c =5.49g/cm ³ , Er ³⁺ ions in the crystal are used as laser-activated ions, and the doping concentration thereof is between 0.5 at.-10 at.%. 2. A preparation method of the erbium-doped tetragadolinium lithium heptamolybdate laser crystal according to claim 1, characterized in that: the crystal is grown by pulling method, with Gd ₂ O ₃ , Li ₂ CO ₃ , MoO ₃ and Er ₂ O ₃ is used as a raw material, and the parameters for crystal growth are growth temperature of 1080° C., lifting speed of 0.5-2.0 mm/hour, and crystal rotation speed of 10-30 revolutions/minute. 3. The application of an erbium-doped tetragadolinium lithium heptamolybdate laser crystal according to claim 1, characterized in that: the crystal is used as a laser working material in a solid-state laser to produce laser output at 550nm and 1500nm wavelengths.