Sapphire and titanium sapphire composite laser crystal and preparation method thereof

Abstract

The invention relates to a sapphire and titanium sapphire composite laser crystal which is composed of sapphire and a titanium sapphire crystal. The doping concentration of the titanium ions is 0-0.8%. And growing by a Bridgman-Stockbarger method. The preparation method has the advantages that 1) the high-quality and large-size composite laser crystal can be obtained through one-time crystal growth, the crystal interface is stable, high power density can be borne, and the crystal is an excellent gain medium of a high-power laser; and 2) the Bridgman-Stockbarger method is utilized to grow the composite crystal, so that the operation steps are simplified, a plurality of crystal surface treatment procedures are omitted, the production cost is reduced, and the possibility of generating defects such as color center, wrappage and degumming in the crystal compounding process can be avoided.

Description

Technical Field

[0001] The present invention relates to a composite laser crystal and a preparation method thereof, in particular to a sapphire and titanium sapphire composite laser crystal and a preparation method thereof, belonging to the technical field of crystal material preparation. Background Art

[0002] Traditional gain media are usually crystals doped with a specific concentration. When the laser is in use, the higher the pump power density, the more susceptible the crystal is to thermal effects, which reduces the output laser beam quality and output power, and even causes the crystal to crack in severe cases. Therefore, how to effectively remove the waste heat generated by the laser is the key to improving the laser beam quality and output power.

[0003] In order to improve the thermal effect of the laser and obtain high-power and high-quality laser output, the existing technology proposes to use composite crystals or bonded crystals as gain media, that is, by compounding or bonding undoped crystals with doped crystals, and using the high thermal conductivity of the undoped crystals to remove waste heat from the doped crystals. This is mainly achieved through the following two ways: (1) using bonding technology to prepare bonded crystals; (2) directly growing composite crystals.

[0004] Bonding is the currently commercialized preparation method. Commonly used crystal bonding technologies include melt bonding technology, low-temperature vacuum thermal bonding technology, and adhesive bonding technology. Melt bonding technology and low-temperature vacuum thermal bonding technology have high requirements on the flatness and smoothness of the crystal surface, and the production process has high requirements on the environment. Adhesive bonding technology has the advantages of simple process and low processing precision requirements. However, the composite crystals prepared by this method have excessive composite bonding surface loss and low bonding strength, which makes it difficult to withstand high power density.

[0005] There are mainly two methods for directly growing composite crystals: the Czochralski method and the optical floating zone method. The Czochralski method for growing composite crystals has high requirements for crystal growth technology. The inoculation of the bottom surface of the block crystal is complex and difficult to control, and it is easy to have defects such as polycrystalline and scattering. The optical floating zone method has a fast growth speed and a short cycle. The crystal growth does not require a crucible, but due to the limitations of the growth method, the crystal diameter is generally small and the internal stress is large.

[0006] The crucible descent method is commonly used for single crystal growth, usually to produce large-sized single crystals. The material for single crystal growth is placed in a cylindrical crucible, slowly descends, and passes through a heating furnace with a certain temperature gradient. The furnace temperature is controlled to be slightly higher than the melting point of the material. According to the properties of the material, the heating device can be a resistance furnace or a high-frequency furnace. When passing through the heating area, the material in the crucible is melted. When the crucible continues to descend, the temperature at the bottom of the crucible first drops below the melting point and begins to crystallize. The single crystal continues to grow as the crucible descends. Summary of the invention

[0007] The present invention provides a sapphire and titanium sapphire composite laser crystal and a preparation method thereof, the purpose of which is to overcome the above-mentioned shortcomings of the prior art and to achieve rapid growth of high-quality, large-sized composite laser crystals through a crucible descent method.

[0008] The technical solution of the present invention is a sapphire and titanium sapphire composite laser crystal, which is composed of sapphire and titanium sapphire crystals.

[0009] Preferably, the doping concentration of titanium ions is 0-0.8%.

[0010] Preferably, the sapphire and titanium sapphire composite laser crystal is grown by a crucible descent method.

[0011] Preferably, the crucible body and the crucible cover are both made of tungsten.

[0012] Preferably, the method comprises the following steps: Step 1) Calculate and accurately weigh each raw material according to the stoichiometric ratio of the titanium sapphire crystal and mix them evenly; Step 2) the mixed raw materials are pressed into shape by isostatic pressing and then placed in a muffle furnace for sintering; Step 3-1) Place a sapphire seed crystal in the crucible, then place the raw materials sintered in step 2) into the crucible, cover the crucible, close the furnace door, evacuate, and fill with protective gas to standard atmospheric pressure; Step 3-2) Turn on the heating power to raise the temperature to the melting point of the raw material, and keep the temperature constant so that the raw material is completely melted; Step 3-3) The crucible is lowered to grow the crystal. After the growth is completed, the temperature is lowered to room temperature and the furnace is opened to obtain a sapphire and titanium sapphire composite laser crystal.

[0013] Preferably, in the step 1), the stoichiometric ratio of titanium sapphire crystal is 0.1%-0.8% Ti:Al2O3, and the raw materials are TiO2 and Al2O3.

[0014] Preferably, the raw materials mixed in step 2) are molded by isostatic pressing at 200 MPa.

[0015] Preferably, in step 3-1), the size of the sapphire seed crystal is ɸ(80-100) mm×(50-80) mm.

[0016] Preferably, in the step 3-1), the furnace door is closed and the vacuum is drawn to (3-10) Pa.

[0017] Preferably, in step 3-2), the heating power is turned on to raise the temperature to 2050° C. and the temperature is kept constant for 0.5-2 hours.

[0018] Preferably, in step 3-3), the crucible is lowered at a speed of (0.5-4) mm / h.

[0019] Preferably, after the growth in step 3-3) is completed, the temperature is cooled to room temperature at a rate of (10-40)°C / h.

[0020] The advantages of the present invention are as follows: 1) high-quality, large-size composite laser crystals can be obtained through one crystal growth, the crystal interface is stable, and it can withstand high power density, and is an excellent gain medium for high-power lasers; 2) The crucible descent method is used to grow composite crystals, which simplifies the operation steps, eliminates multiple crystal surface treatment processes, reduces production costs, and avoids the possibility of defects such as color centers, inclusions, and debonding during the crystal composite process. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to examples and specific implementation modes.

[0022] A sapphire and titanium sapphire composite laser crystal consists of sapphire and titanium sapphire crystals, wherein the doping concentration of titanium ions is 0-0.8%.

[0023] The composite laser crystal is grown by the crucible descent method, where both the crucible body and the crucible cover are made of tungsten, and includes the following steps: Step 1) Calculate and accurately weigh each raw material according to the stoichiometric ratio of titanium sapphire (Ti:Al2O3) crystal and mix them evenly; Step 2) the mixed raw materials are pressed into a mold by isostatic pressing and then placed in a crucible for sintering; Step 3) Place a sapphire seed crystal of appropriate size in the crucible, then place the raw material sintered in step 2) into the crucible, cover the crucible, close the furnace door, evacuate to (3-10) Pa, and fill with protective gas to standard atmospheric pressure; turn on the heating power to raise the temperature to the melting point of the raw material; after maintaining the constant temperature for (0.5-2) h, completely melt the raw material; slowly lower the crucible at a speed of (0.5-4) mm / h to grow the crystal, and after the growth is completed, slowly cool to room temperature at (10-40) ° C / h, and open the furnace to obtain a composite laser crystal. Example 1

[0024] A sapphire and titanium sapphire composite laser crystal, wherein the doping concentration of titanium ions is 0.1%. The composite laser crystal is grown by a crucible descent method, comprising the following steps: Step 1) Calculate and accurately weigh TiO2 and Al2O3 raw materials according to the stoichiometric ratio of titanium sapphire (0.1% Ti:Al2O3) crystal and mix them evenly; Step 2) the mixed raw materials are pressed into shape by isostatic pressing at 200 MPa and then placed in a crucible for sintering; Step 3) Place ɸ80mm×50mm sapphire as seed crystal in the crucible, then put the titanium sapphire raw material sintered in step 2) into the crucible, cover the crucible, close the furnace door, evacuate to 3Pa, and fill with protective gas to standard atmospheric pressure; turn on the heating power and raise the temperature to 2050℃; after keeping the temperature constant for 1h, the raw material is completely melted; slowly lower the crucible at a speed of 4mm / h to grow the crystal, and after the growth is completed, slowly cool to room temperature at 40℃ / h, and open the furnace to obtain a composite laser crystal of sapphire and titanium sapphire. Example 2

[0025] A sapphire and titanium sapphire composite laser crystal, wherein the doping concentration of titanium ions is 0.4%. The composite laser crystal is grown by a crucible descent method, comprising the following steps: Step 1) Calculate and accurately weigh TiO2 and Al2O3 raw materials according to the stoichiometric ratio of titanium sapphire (0.4% Ti:Al2O3) crystal and mix them evenly; Step 2) the mixed raw materials are pressed into shape by isostatic pressing at 200 MPa and then placed in a crucible for sintering; Step 3) Place a sapphire of ɸ100mm×80mm as a seed crystal in the crucible, then place the titanium sapphire raw material sintered in step 2) into the crucible, cover the crucible, close the furnace door, evacuate to 5Pa, and fill with protective gas to standard atmospheric pressure; turn on the heating power and raise the temperature to 2050℃; after keeping the temperature constant for 2h, completely melt the raw material; slowly lower the crucible at a speed of 2mm / h to grow the crystal, and after the growth is completed, slowly cool to room temperature at 20℃ / h, and open the furnace to obtain a composite laser crystal of sapphire and titanium sapphire. Example 3

[0026] A sapphire and titanium sapphire composite laser crystal, wherein the doping concentration of titanium ions is 0.8%. The composite laser crystal is grown by a crucible descent method, comprising the following steps: Step 1) Calculate and accurately weigh TiO2 and Al2O3 raw materials according to the stoichiometric ratio of titanium sapphire (0.8% Ti:Al2O3) crystal and mix them evenly.

[0027] Step 2) The mixed raw materials are pressed into shape by isostatic pressing at 200 MPa and then placed in a crucible for sintering.

[0028] Step 3) Place a sapphire of ɸ100mm×80mm as a seed crystal in the crucible, then place the titanium sapphire raw material sintered in step 2) into the crucible, cover the crucible, close the furnace door, evacuate to 4Pa, and fill with protective gas to standard atmospheric pressure; turn on the heating power and heat to 2050℃; keep the temperature constant for 2h to completely melt the raw material. Slowly lower the crucible at a speed of 0.5mm / h to grow the crystal. After the growth is completed, slowly cool it to room temperature at 10℃ / h, and open the furnace to obtain a composite laser crystal of sapphire and titanium sapphire.

[0029] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, which all fall within the protection scope of the present invention.

Claims

1. A sapphire and titanium sapphire composite laser crystal, characterized in that: It is composed of sapphire and titanium sapphire crystals, with a titanium ion doping concentration of 0-0.8%, and is grown using the crucible descent method.

2. A sapphire and titanium sapphire composite laser crystal as claimed in claim 1, characterized in that: The crucible body and crucible cover are both made of tungsten.

3. The method for preparing a sapphire and titanium sapphire composite laser crystal according to claim 1 or 2, characterized in that: The following steps are involved: Step 1) Calculate and accurately weigh each raw material according to the stoichiometric ratio of the titanium sapphire crystal and mix them evenly; Step 2) the mixed raw materials are pressed into shape by isostatic pressing and then placed in a muffle furnace for sintering; Step 3-1) Place a sapphire seed crystal in the crucible, then place the raw materials sintered in step 2) into the crucible, cover the crucible, close the furnace door, evacuate, and fill with protective gas to standard atmospheric pressure; Step 3-2) Turn on the heating power to raise the temperature to the melting point of the raw material, and keep the temperature constant so that the raw material is completely melted; Step 3-3) The crucible is lowered to grow the crystal. After the growth is completed, the temperature is lowered to room temperature and the furnace is opened to obtain a sapphire and titanium sapphire composite laser crystal.

4. The method for preparing a sapphire and titanium sapphire composite laser crystal according to claim 3, characterized in that: In the step 1), the stoichiometric ratio of the titanium sapphire crystal is 0.1%-0.8% Ti:Al2O3, and the raw materials are TiO2 and Al2O3.

5. The method for preparing a sapphire and titanium sapphire composite laser crystal according to claim 3, characterized in that: The raw materials mixed in step 2) are pressed and molded by isostatic pressing at 200 MPa.

6. The method for preparing a sapphire and titanium sapphire composite laser crystal according to claim 3, characterized in that: In the step 3-1), the size of the sapphire seed crystal is ɸ(80-100) mm×(50-80) mm.

7. The method for preparing a sapphire and titanium sapphire composite laser crystal according to claim 3, characterized in that: In the step 3-1), the furnace door is closed and the vacuum is drawn to (3-10) Pa.

8. The method for preparing a sapphire and titanium sapphire composite laser crystal according to claim 3, characterized in that: In the step 3-2), the heating power is turned on to raise the temperature to 2050° C. and the temperature is kept constant for (0.5-2) hours.

9. The method for preparing a sapphire and titanium sapphire composite laser crystal according to claim 3, characterized in that: In the step 3-3), the crucible is lowered at a speed of (0.5-4) mm / h.

10. The method for preparing a sapphire and titanium sapphire composite laser crystal according to claim 3, characterized in that: After the growth in step 3-3) is completed, the temperature is cooled to room temperature at a rate of (10-40)°C / h.