CN103397385B - Mix ytterbium lutetium GGG laser crystal and preparation method thereof and application - Google Patents

Abstract

The invention provides a ytterbium-doped lutetium-gadolinium-gallium garnet laser crystal and a preparation method and application thereof. The molecular formula of the crystal is (Yb _y Lu _x Gd _1-xy ) ₃ Ga ₅ O ₁₂ , 0<x<1, 0.01≤y≤0.5, and x+y≤1; Yb ³⁺ acts as an active ion in the laser diode (LD) or other laser pumps can achieve continuous and pulsed laser output near 1 μm. The present invention adopts the melt pulling method to grow the crystal Yb:(Lux Gd _{1-x ) 3} Ga ₅ O ₁₂ . In the present invention, part of Lu ³⁺ is doped into the dodecahedral site of Yb:GGG crystal to obtain Yb:LGGG crystal. The crystal growth interface is stable, the crystal quality is high, and it can be used as a laser crystal for generating continuous laser output, Q-switched laser, and mode-locked laser.

Description

Ytterbium-doped lutetium-gadolinium-gallium garnet laser crystal and its preparation method and application

technical field

The invention relates to a new type of laser crystal and its growth and application, in particular to a laser crystal doped with ytterbium, lutetium, gadolinium and gallium garnet (Yb:LGGG), a growth method and application, and belongs to the technical field of crystals and devices.

technical background

Laser is one of the greatest inventions of the 20th century. It has excellent characteristics such as good coherence, good directionality, and high brightness. Since the birth of the first ruby laser in 1960, laser technology has shown a rapid development trend in miniaturization, high power, narrow pulse, etc., and has been widely used in industry, military, medical, communication and other fields, creating a new situation in the field of optics , to promote the development of optoelectronic technology.

At present, there are many kinds of lasers, which can be divided into gas, solid, dye and semiconductor lasers according to the classification of working substances. Among them, solid-state laser technology, as an irreplaceable cutting-edge technology in important fields such as information, industry, and national defense, has attracted widespread attention. Laser working substances are the core and foundation of the development of solid-state laser technology, so high-efficiency laser materials are a milestone in the development of solid-state lasers.

Ytterbium-doped gadolinium-gallium garnet crystal (Yb:GGG) is a laser material with potential application value: on the one hand, the active ion Yb ³⁺ has many excellent characteristics: ①The energy level structure is simple, with only two electronic states (ground state ² F _7/2 and excited state ² F _5/2 ), there is no excited state absorption and upconversion, and the photoconversion efficiency is high; ②The pump wavelength is close to the laser emission wavelength, and the quantum efficiency can be as high as 90% in theory; ③In Concentration quenching will not occur at a relatively high doping concentration; ④The fluorescence lifetime is long, which is conducive to energy storage. On the other hand, gadolinium gallium garnet has the advantages of good mechanical properties, high thermal conductivity, high hardness, and stable physical and chemical properties. It can grow large-sized, core-free crystals by pulling method, and is the preferred matrix for high-power laser output. Material. Therefore, the thermal, spectroscopic and laser properties of ytterbium-gadolinium-gallium garnet crystals have been extensively studied. Through in-depth research, it is found that the ionic radius of Yb ³⁺ is smaller than that of Gd ³⁺ , so its effective segregation coefficient in the crystal is greater than 1, which will cause the concentration of Yb ³⁺ in the crystal to gradually decrease from top to bottom. Especially when growing large-sized crystals, the amount of raw materials used will be very large, and the problem of concentration gradients in the crystals will be more prominent at this time. The uneven doping of Yb ³⁺ in the crystal will lead to poor optical uniformity of the crystal, which will directly affect the beam quality of the laser. In addition, when the segregation coefficient is much greater than 1, it will bring a series of problems to the crystal growth, such as: the problem of supercooling of the components, the instability of the growth interface, etc.

Contents of the invention

Aiming at the problems existing in the prior art, the present invention provides a ytterbium-doped lutetium-gadolinium-gallium garnet laser crystal and its preparation method and application. The ytterbium-lutetium-gadolinium-gallium garnet crystal can realize high-efficiency continuous and pulsed laser output.

Technical scheme of the present invention is as follows:

A ytterbium-lutetium-gadolinium-gallium garnet laser crystal doped with a molecular formula of (Yb _y Lu _x Gd _1-xy ) ₃ Ga ₅ O ₁₂ , 0<x<1, 0.01≤y≤0.5, and x+y≤ 1.

The crystal belongs to the cubic crystal system, and the space group is Oh (10) _-Ia3d . Among them, both Yb ³⁺ and Lu ³⁺ are Gd ³⁺ replacing crystal dodecahedral sites.

Yb-doped lutetium-gadolinium-gallium garnet laser crystal, the chemical formula is Yb:(Lux Gd _{1-x ) 3} Ga ₅ O ₁₂ , where the doping concentration of Yb ³⁺ is 1-50 at.%. Yb ³⁺ is used as an active ion, and under the pump of laser diode (LD) or other lasers, it can realize continuous and pulsed laser output near 1 μm.

Preferably according to the present invention, in the molecular formula (Yb _y Lu _x Gd _1-xy ) ₃ Ga ₅ O ₁₂ , x=0.05-0.25, y=0.05-0.45; more preferably, x=0.05, y=0.05-0.15.

A method for preparing ytterbium-lutetium-gadolinium-gallium garnet crystals is grown by a melt pulling method, and the steps are as follows:

(1) Synthesis of polycrystalline materials

According to the molecular formula (Yb _y Lu _x Gd _1-xy ) ₃ Ga ₅ O ₁₂ stoichiometric ratio, weigh raw materials Yb ₂ O ₃ , Lu ₂ O ₃ , Gd ₂ O ₃ and Ga ₂ O ₃ Make Ga ₂ O ₃ excess 1-3wt.%, based on the Ga ₂ O ₃ mass calculated according to the stoichiometric ratio;

The polycrystalline material of ytterbium, lutetium, gadolinium and gallium garnet is synthesized by solid phase sintering method or liquid phase method.

(2) Crystal growth

Put the prepared polycrystalline material into an iridium gold crucible, put it into a pulling furnace, evacuate, and fill with protective gas; heat up to melt the polycrystalline material, and after the melt is fully mixed, place the seed crystal and start growing the crystal; Pulling speed: 0.5-5mm/hour, rotating speed: 5-60 rpm; when the crystal grows to the required size, extract the crystal, cool it down to room temperature at a rate of 10-60℃/hour, and take it out of the furnace; the crystal after being out of the furnace Annealing is carried out in air, and the annealing temperature is 1200-1500°C.

In the preparation method of the present invention, especially considering the volatilization and decomposition of Ga ₂ O ₃ during the crystal growth process, step (1) makes the excess 1-3wt.% when batching, preferably, the excess of Ga ₂ O ₃ is 2wt. %, based on the mass of Ga ₂ O ₃ calculated according to the stoichiometric ratio.

According to the preparation method of the present invention, the protective gas in step (2) is argon or nitrogen.

According to the preparation method of the present invention, the seed crystal in step (2) is Nd:GGG crystal. Nd:GGG is an abbreviation for neodymium-doped gadolinium gallium garnet, which is an existing crystal in the field.

According to the preparation method of the present invention, preferably, when growing the crystal in step (2), the pulling speed is 1-3 mm/hour, and the rotating speed is 20-25 rpm.

The raw materials Yb ₂ O ₃ , Lu ₂ O ₃ , Gd ₂ O ₃ and Ga ₂ O ₃ used in the present invention all have a purity of 99.99%.

Preferably, according to the present invention, the solid phase sintering method described in step (1) synthesizes the polycrystalline material of ytterbium, lutetium, gadolinium and gallium garnet: fully mixing the prepared raw materials, and then pressing the raw materials into a cylindrical block , put it into a corundum crucible, and use a sintering furnace to calcinate at 1200-1500°C for 25-35 hours to obtain polycrystalline material of ytterbium-doped lutetium-gadolinium-gallium garnet.

Preferably, according to the present invention, the liquid-phase method described in step (1) to synthesize the polycrystalline material of ytterbium-lutetium-gadolinium-gallium garnet is: react the prepared raw materials with concentrated nitric acid to obtain Yb(NO ₃ ) ₃ , Lu( NO ₃ ) ₃ , Gd(NO ₃ ) ₃ and Ga(NO ₃ ) ₃ nitrate mixed solution, then adjust the pH value of the mixed solution to 4-5 with ammonia water, then add ammonium bicarbonate solution for precipitation, and pass the obtained precipitate through Multiple times of centrifugation, drying, and finally tableting and calcination to obtain a polycrystalline material doped with ytterbium, lutetium, gadolinium and gallium garnet.

The concentrated nitric acid mentioned above has a concentration mass fraction of 65-68% well known in the art; ammonia water is a pH regulator, and the concentration is not limited, and conventional commercially available ammonia water with a mass fraction of 25-28% is sufficient. Ammonium bicarbonate, commercially available industrial grade, prepared into a solution with a concentration of 2-2.6mol/L.

When the ytterbium-doped lutetium-gadolinium-gallium garnet crystal of the present invention is used as a laser crystal material, the grown crystal needs to be processed and polished before use; both ends of the crystal are polished or further coated with a dielectric film, and the light-transmitting surface of the crystal is circular or square.

The application of ytterbium-lutetium-gadolinium-gallium garnet crystals as laser crystal materials includes any of the following:

Application of ytterbium-lutetium-gadolinium-gallium garnet crystals doped with laser crystals for continuous laser output;

Application of ytterbium-lutetium-gadolinium-gallium garnet crystal doped with Q-switched laser material;

Application of ytterbium-lutetium-gadolinium-gallium garnet crystal doped with mode-locked laser material.

Preferred according to the invention:

1. The ytterbium-lutetium-gadolinium-gallium-doped garnet crystal of the present invention is used in continuous laser devices, and the ytterbium-lutetium-gadolinium-gallium garnet crystal is used as a laser crystal, which is pumped by a laser diode (LD) or other lasers to achieve continuous laser output near 1025nm.

2. Ytterbium-doped lutetium-gadolinium-gallium garnet crystals are used for Q-switched laser devices, and ytterbium-doped lutetium-gadolinium-gallium garnet crystals are used as laser crystals and Q-switching components, including electro-optical Q-switching components, acousto-optic Q-switching components or saturable absorbers. In the laser cavity, laser diode (LD) or other laser pumps are used to achieve Q-switched laser output near 1025nm.

3. The application of ytterbium-lutetium-gadolinium-gallium garnet crystal doped as a working material for mode-locked laser output.

In the present invention, part of Lu ³⁺ is doped into the dodecahedral site of the ytterbium-doped gadolinium-gallium garnet (Yb:GGG) crystal to obtain the ytterbium-doped lutetium-gadolinium-gallium garnet crystal (Yb:LGGG). The crystal is not only isomorphic with the ytterbium-doped gadolinium-gallium garnet crystal, but also has the following advantages: ①The introduction of Lu ³⁺ makes the crystal structure more complex and disordered, and the addition of Gd ³ The random distribution of ⁺ and Lu ³⁺ around Yb ³⁺ will lead to the inhomogeneity of the coordination field of the activated ions. These factors will bring about the non-uniform broadening of the spectrum of the crystal, which is conducive to the operation of ultrafast lasers; ② the radius of doping ions is small Lu ³⁺ can make the effective segregation coefficient of Yb ³⁺ in the ytterbium-lutetium-gadolinium-gallium garnet crystal tend to the ideal value of 1, solve the problems of component overcooling and unstable growth interface, and help improve the crystal quality. ③ Ytterbium-doped lutetium-gadolinium-gallium garnet crystal is a new type of laser material. At present, there are no relevant reports on Ytterbium-doped lutetium-gadolinium-gallium garnet crystal as a laser crystal at home and abroad.

The invention adopts the pulling method to grow the garnet crystal doped with ytterbium, lutetium, gadolinium and gallium, and the operation is simple and the growth period is short; the prepared crystal has high doping (no concentration quenching), long upper energy level life, absorption and emission spectral bandwidth, It has the advantages of high quantum efficiency, excellent thermal and spectral properties, and can realize the growth of flat interface core-free crystals; large-sized single crystals can be prepared by using large-sized crucibles; the obtained crystals can be easily processed into laser devices to achieve high-efficiency laser output; this method uses All raw materials are available in the market.

Description of drawings

Fig. 1 is a comparison of the XRD (upper) and the standard diffraction spectrum (lower) of the gadolinium-gallium garnet of the polycrystalline powder of ytterbium-lutetium-gadolinium-gallium garnet prepared in Example 1.

Fig. 2 is a photo of the nearly flat interface doped ytterbium lutetium gadolinium gallium garnet crystal prepared in Example 1.

Fig. 3 is a schematic diagram of the laser device test used in Example 5 and Example 6. Among the figure, 1. semiconductor laser, 2. fiber coupling system, 3. focusing system, 4. concave mirror, 5. ytterbium-doped lutetium-gadolinium-gallium garnet crystal, 6. saturable absorber V ³⁺ : YAG crystal, 7. output coupling mirror.

FIG. 4 is a continuous laser output curve in Example 5.

Fig. 5 is a schematic diagram of a weighing automatic diameter control (ADC) system device in the prior art. In the figure, 21, lifting rod, 22, seed crystal, 23, growing crystal, 24, polycrystalline material melt, 25, iridium gold crucible, 26, quartz sleeve, 27, zirconia sand, 28, radio frequency coil, 29. Zirconia felt, 30. Zirconia sleeve, 31. Support, 32. Zirconia sand, 33. Base, 34. Automatic control system, 35. DSP intermediate frequency power supply.

detailed description

The present invention will be further described below in conjunction with the examples, but not limited thereto.

Example 1: x=0.05, y=0.05, ytterbium lutetium gadolinium gallium garnet crystal chemical formula is Yb _0.15 Lu _0.15 Gd _2.7 Ga ₅ O ₁₂

The preparation method of doped ytterbium lutetium gadolinium gallium garnet crystal is as follows:

(1) Synthesis of polycrystalline material by solid phase sintering method

The initial raw materials are Yb ₂ O ₃ , Lu ₂ O ₃ , Gd ₂ O ₃ and Ga ₂ O ₃ , all of which have a purity of 99.99%. The chemical reaction equation is as follows:

0.15Yb ₂ O ₃ +0.15Lu ₂ O ₃ +2.7Gd ₂ O ₃ +5Ga ₂ O ₃ =2Yb _0.15 Lu _0.15 Gd _2.7 Ga ₅ O ₁₂

Weigh the corresponding raw materials Yb ₂ O ₃ , Lu ₂ O ₃ , Gd ₂ O ₃ and Ga ₂ O ₃ according to the stoichiometric ratio of Yb _0.15 Lu _0.15 Gd _2.7 Ga ₅ O ₁₂ , considering the presence of Ga ₂ O ₃ in the crystal growth process The volatilization and decomposition of Ga 2 O 3 in the batching process make the Ga ₂ O ₃ excess 2wt.% (according to the Ga ₂ O ₃ mass calculated according to the stoichiometric ratio). Then put into the mixer and mix fully, the mixing time is 48 hours. After the mixing is completed, use a hydraulic press to press the raw materials into a cylindrical block, put them into a corundum crucible, and use a sintering furnace to calcinate at 1300 ° C for 30 hours to obtain ytterbium-doped lutetium-gadolinium-gallium garnet polycrystalline material, and its powder XRD is shown in Figure 1, the peaks in the figure are in good agreement with the standard diffraction pattern of gadolinium gallium garnet, indicating that the synthesized is a high-purity ytterbium doped lutetium gadolinium gallium garnet polycrystalline material.

(2) Growth of ytterbium, lutetium, gadolinium and gallium garnet crystals by melt pulling method

During the whole crystal growth process, the furnace is filled with argon as a protective gas to prevent oxidation of the iridium crucible. The specific process of crystal growth includes: placing the sintered ytterbium-doped lutetium-gadolinium-gallium garnet polycrystalline material in a clean iridium gold crucible, the size of the crucible is Φ60mm×35mm, heating the material by medium frequency induction, and overheating at about 20°C Keep the temperature constant for 20-60 minutes to make the melt fully mixed evenly and reduce the crystallites existing in the melt. Then slowly insert the Nd:GGG seed crystal, adjust the seeding temperature to make the seed crystal micro-melt and shrink the diameter, when the diameter of the seed crystal is reduced to 2-3mm, enter the automatic diameter control program to carry out the stages of shouldering, equal diameter, and finishing. . The pulling speed and rotational speed during the growth were 1 mm/h and 20-25 rpm, respectively. When the crystal grows to about 53mm (height), extract the crystal, then slowly lower it to room temperature at a rate of 50-55°C/hour, and take it out of the furnace.

The above automatic diameter control (ADC) system for weighing is the prior art, and the schematic diagram of the device is shown in FIG. 5 .

After the crystal growth is completed, high-temperature air atmosphere annealing is performed on the ytterbium-lutetium-gadolinium-gallium garnet crystal to eliminate thermal stress in the crystal and oxygen vacancies caused by an oxygen-deficient environment and improve crystal quality. The specific annealing procedure is as follows: the grown ytterbium-lutetium-gadolinium-gallium garnet crystal is heated to 1400° C. for 15 hours at a constant temperature, and then slowly lowered to room temperature. Fig. 2 is a photo of the nearly flat interface doped ytterbium lutetium gadolinium gallium garnet crystal obtained by growth, the crystal size is Φ26mm×30mm, the shape is complete, and there is no crack.

Example 2: x=0.05, y=0.15, ytterbium-doped lutetium-gadolinium-gallium garnet crystal chemical formula is Yb _0.45 Lu _0.15 Gd _2.4 Ga ₅ O ₁₂

Weigh the corresponding raw materials Yb ₂ O ₃ , Lu ₂ O ₃ , Gd ₂ O ₃ and Ga ₂ O ₃ according to the stoichiometric ratio of Yb _0.45 Lu _0.15 Gd _2.4 Ga ₅ O ₁₂ , and make Ga ₂ O ₃ excess 3wt.% (by According to the _Ga2O3 mass calculated by the stoichiometric ratio ₎ , and then fully mixed, the mixing time is 50 hours. Use a hydraulic press to press the raw material into a cylindrical block, put it into a corundum crucible, and use a sintering furnace to calcinate at 1350 ° C for 30 hours to obtain the ytterbium-doped lutetium-gadolinium-gallium garnet polycrystalline material.

(2) Crystal growth

As described in step (2) in Example 1, the difference is: during the crystal growth process, the pulling speed is reduced to: 0.5mm/hour; after the crystal growth is completed and stripped, the cooling rate is 40°C/hour.

Example 3:

As described in Example 1, the difference is that the liquid phase method is used to synthesize the polycrystalline material

React raw materials Yb ₂ O ₃ , Lu ₂ O ₃ , Gd ₂ O ₃ and Ga ₂ O ₃ with concentrated nitric acid (mass fraction about 65%), and add hydrochloric acid (mass fraction about 35% ) to promote the reaction process to obtain Yb(NO ₃ ) ₃ , Lu(NO ₃ ) ₃ , Gd(NO ₃ ) ₃ and Ga(NO ₃ ) ₃ four nitrate mixed solutions, and then use ammonia water to adjust the pH value of the mixed solution to 4.5 , and then slowly add 2mol·L ^-1 ammonium bicarbonate solution until no bubbles are generated in the solution, and the pH=7 at this time. The obtained precipitate was centrifuged out by a centrifuge, then washed with distilled water and centrifuged again, and the operation was repeated twice. Then the precipitate is dried in a drying oven, pressed into thin sheets by a press and calcined at 800°C for 10 hours to obtain a polycrystalline material of ytterbium-doped lutetium-gadolinium-gallium garnet.

Example 4: x=0.25, y=0.45, ytterbium lutetium gadolinium gallium garnet crystal chemical formula is Yb _1.35 Lu _0.75 Gd _0.9 Ga ₅ O ₁₂

As described in Example 1, the difference is: Weigh the corresponding raw materials Yb ₂ O ₃ , Lu ₂ O ₃ , Gd ₂ O ₃ and Ga ₂ O ₃ according to the stoichiometric ratio of Yb _1.35 Lu _0.75 Gd _0.9 Ga ₅ O ₁₂ , Considering the volatilization and decomposition of Ga ₂ O ₃ during the crystal growth process, the excess of Ga ₂ O ₃ is 2wt.% (based on the mass of Ga ₂ O ₃ calculated according to the stoichiometric ratio) when batching.

Put the sintered ytterbium-doped lutetium-gadolinium-gallium garnet polycrystalline material in an iridium gold crucible, heat the polycrystalline material, and overheat at 20°C for 40 minutes to make the melt fully mixed evenly, and then slowly pour Nd:GGG seed crystal. The pulling speed and rotational speed during the growth were 1.5 mm/h and 25-30 rpm, respectively. When the crystal grows to about 45mm, the crystal is extracted, and then slowly lowered to room temperature at a rate of 30-40°C/hour, and then taken out of the furnace.

Example 5:

The laser device manufactured by the laser crystal of Example 1 realizes continuous laser output near 1025nm, and the laser test device is shown in Figure 3 (during continuous laser operation, it is necessary to remove the saturable absorber V ³⁺ in the figure: YAG crystal 6), along the optical path It consists of semiconductor laser 1, fiber coupling system 2, focusing system 3, concave mirror 4, ytterbium-doped lutetium-gadolinium-gallium garnet crystal 5, saturable absorber V ³⁺ :YAG crystal 6, and output coupling mirror 7.

The test sample is Yb _0.15 Lu _0.15 Gd _2.7 Ga ₅ O ₁₂ crystal, the size is 4mm×4mm×5mm, the transparent surface is coated, wrapped with indium foil and placed in a water-cooled aluminum block, the temperature of the cooling water is maintained at 16°C. The radius of curvature of the concave mirror 4 is 100mm, the front surface is coated with an anti-reflective dielectric film of 940nm (the reflectance of light waves at 940nm is less than 0.5%), and the rear surface is coated with a dielectric film with high transparency of 942nm and high reflection of 1010-1100nm (light waves at 1010-1100nm The reflectivity is greater than 99.8%); the plane mirror 7 is an output coupling mirror, and the transmittance at 1010-1070nm is 1% and 5% respectively. The pumping source is a semiconductor laser 1, which can output a maximum pumping power of 30W, the center wavelength of emission is 942nm, and the spot radius and numerical aperture are 400μm and 0.22 respectively. The laser is focused into the ytterbium-doped lutetium-gadolinium-gallium garnet crystal 5, and then the laser is output through the saturable absorber V ³⁺ :YAG crystal 6 and the output coupling mirror 7 . A power meter (Fieldmax II, Coherent) was used to test the average laser output power. The laser cavity length is optimized to 20mm. When the transmittance of the output mirror is 5%, the maximum continuous laser output power near 1025nm is 4.3W, as shown in Figure 4.

Embodiment 6: The laser device manufactured by the laser crystal of Embodiment 2 realizes the passive Q-switched laser output near 1025 nm.

The passive Q-switched laser test was performed using the laser device in Example 5. V ³⁺ : YAG crystal is used as a saturable absorber, its size and initial transmittance are 3mm×3mm×2mm and 97% respectively. The laser pulse signal is recorded by a Tektronix DPL7104 oscilloscope (bandwidth 1GHz, sampling speed 5Gs/s) and a photodetector (Newfocus, model 1611, rising speed ≤ 1ns). Under the action of pump light, passive Q-switched laser output near 1025nm can be realized.

Claims (6)

1. mix a preparation method for ytterbium lutetium substitute GGG crystal, described in mix ytterbium lutetium substitute GGG crystal molecular formula be (Yb _ylu _xgd _1-x-y) ₃ga ₅o ₁₂, 0<x<1,0.01≤y≤0.5, and x+y≤1; Adopt melt Czochralski grown, step is as follows:

(1) polycrystal synthesis

By molecular formula (Yb _ylu _xgd _1-x-y) ₃ga ₅o ₁₂stoichiometric ratio, takes raw material Yb ₂o ₃, Lu ₂o ₃, Gd ₂o ₃and Ga ₂o ₃, and make Ga more on this basis ₂o ₃excessive 1-3wt.%, with the Ga stoichiometrically calculated ₂o ₃quality meter; Solid sintering technology or liquid phase method synthesis is adopted to mix the polycrystal of ytterbium lutetium gadolinium gallium garnet;

(2) crystal growth

Obtained polycrystal is loaded in Iridium Crucible, load lifting furnace, vacuumize, fill protection gas argon gas or nitrogen; Intensification makes polycrystal melt, and after melt fully mixes, lower seed crystal, starts growing crystal; Pull rate: 0.5-5mm/ hour, rotating speed: 5-60 rev/min; When crystal growth is to desired size, carry de-crystal, cool to room temperature with the speed of 10-60 DEG C/h, come out of the stove; Crystal after coming out of the stove is annealed in atmosphere, and annealing temperature is 1200-1500 DEG C.

2. mix the preparation method of ytterbium lutetium substitute GGG crystal as claimed in claim 1, described in it is characterized in that, mix x=0.05-0.25, y=0.05-0.45 in the molecular formula of ytterbium lutetium substitute GGG crystal.

3. mix the preparation method of ytterbium lutetium substitute GGG crystal as claimed in claim 1, described in it is characterized in that, mix x=0.05, y=0.05-0.15 in the molecular formula of ytterbium lutetium substitute GGG crystal.

4. mix the preparation method of ytterbium lutetium substitute GGG crystal as claimed in claim 1, it is characterized in that Ga in step (1) ₂o ₃excessive 2wt.%.

5. mix the preparation method of ytterbium lutetium substitute GGG crystal as claimed in claim 1, it is characterized in that described in step (2), seed crystal is Nd:GGG crystal.

6. mix the preparation method of ytterbium lutetium substitute GGG crystal as claimed in claim 1, when it is characterized in that growing crystal in step (2), pull rate: 1-3mm/ hour, rotating speed 20-25 rev/min.