Rare earth and thorium ion co-doped LaAlO3 laser crystals, their preparation and applications

Abstract

A rare earth ion and thorium co-doped LaAlO3 perovskite type laser crystal, by doping thorium ions in LaAlO3 crystal, rhombic domain is single domain, and single domain crystal without scattering along the laser direction is obtained. ‑1 LaAlO3 crystal has lower phonon energy (486cm ‑1 K ‑1 ), larger thermal conductivity (13.6Wm -1 K -1 ), after Nd and Th co-doping, the fluorescence lifetime of Nd is up to 317us, which is the longest in current oxide laser crystal. The crystal growth method provided by the application can grow high-quality single crystal with single domain, and as a gain medium, can produce large energy nanosecond pulse laser, which has great application in many fields such as industry, scientific research, national defense and medicine.

Description

Technical Field

[0001] This invention relates to the field of laser crystal gain material technology, specifically to a rare earth ion and thorium ion co-doped LaAlO3 laser crystal, its preparation and application. Background Technology

[0002] High-repetition-rate (PRR) high-energy pulsed lasers possess advantages such as high single-pulse energy, high peak power, and certain repetition rate performance, playing a vital role in numerous fields including industry, scientific research, defense, and medicine. With the development of diode-pumped solid-state lasers (DPSSLs), pulsed lasers with high average power, large peak pulse size, high efficiency, high repetition rate, high reliability, and high beam quality are increasingly meeting application requirements and expanding into new application scenarios. These applications include, but are not limited to:

[0003] 1) Laser shock peening. Laser shock peening uses high-energy lasers at the nanosecond scale to treat workpieces, which can significantly improve the strength, wear resistance, and fatigue resistance of materials. It is widely used in high-end manufacturing, such as blades of aero-engines, welding of special pipes, and pistons and cylinders of automobile engines.

[0004] 2) Inertial confinement fusion laser drive source. A high-power laser is used to irradiate the target, compressing the fuel inward. The plasma formed by the target material is heated to extremely high temperatures and undergoes a fusion reaction before it can disperse due to its own inertia.

[0005] 3) Strong Field Physics. Using lasers to create high-energy-density matter states similar to celestial environments, exploring the structure and properties of matter under extreme conditions; driving petawatt-level solid-state lasers to achieve efficient and compact X-ray, gamma-ray, and other radiation sources, exciting particle source generation and acceleration.

[0006] Existing gain media used in large-pulse lasers are mainly Nd:YAG, Nd:LuAG, and neodymium glass. However, neodymium glass suffers from low thermal conductivity, limiting its repetition rate. Nd:YAG and Nd:LuAG have low saturation flux, making it difficult to increase the maximum pulse energy. Therefore, there is an urgent need to develop a laser crystal with high thermal conductivity, long fluorescence lifetime, and suitable saturation flux.

[0007] The perovskite-structured LaAlO3 crystal undergoes a phase transition from a cubic to a rhombic structure near 820 K, resulting in the formation of rhombic domains that cause significant scattering of light beams. At room temperature, it belongs to the monoclinic crystal system and has a low phonon energy of approximately 486 cm⁻¹. -1 With a melting point of 2080℃, it is easily grown using methods such as the Czochralski method, crucible lowering method, and heat exchange method. When Nd is doped... 3 + Yb 3+ Tm3+ Ho 3+ Rare earth ions and Th 4+ In LaAlO3 crystals with doped ions, dopant ions replace La 3+ Located at the center of the oxygen octahedron formed by Al and O atoms, this type of rare-earth ion-doped laser exhibits strong electric dipole luminescence transitions, enabling efficient laser output. However, during the crystal's growth, a phase transition occurs, generating numerous rhombic domain structures that cause significant beam scattering, hindering effective laser output. Overcoming the rhombic domain structure is crucial for the practical application of LaAlO3 as a laser crystal. Currently, there are no reports of rare-earth ion and thorium ion co-doped laser crystals, either domestically or internationally. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention proposes a rare-earth ion and thorium ion co-doped LaAlO3 laser crystal, which enables the crystal to obtain a stable single-domain structure and is used in the field of high-repetition-rate high-energy pulsed lasers. This crystal has important application prospects in industry, scientific research, national defense, medicine and other fields.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] On one hand, this invention provides a rare-earth ion and thorium ion co-doped LaAlO3 laser crystal, characterized in that: the molecular formula of the crystal is: A x Th y La (1-x-1.33y) AlO3, where A is a trivalent rare earth ion, 0.001≤x≤0.05, 0<y≤0.05.

[0011] Preferably, A is Nd 3+ Yb 3+ Er 3+ Ho 3+ or Tm 3 Trivalent rare earth ions.

[0012] Preferably, the trivalent rare earth ion doping concentration range is 0.0025≤x≤0.015; and the doped thorium ion content range is 0.002≤y≤0.02.

[0013] Preferably, the trivalent rare earth ion doping concentration is x=0.01; the doped thorium ion concentration is y=0.004.

[0014] Preferably, the crystal belongs to the monoclinic crystal system, with space group R-3c, cell parameters a=0.537, b=0.537, c=13.24, and has a pseudocubic structure at room temperature with phonon energy less than 486. .

[0015] Preferably, the fluorescence lifetime of the crystal is not less than 317.7. .

[0016] On the other hand, the present invention also provides a method for preparing a LaAlO3 laser crystal co-doped with rare earth ions and thorium ions, characterized by comprising the following steps:

[0017] S1. Weigh the raw materials, including A2O3, Al2O3, La2O3, and ThO2, all with a purity greater than 99.999%, according to the molar ratio of each substance in the molecular formula.

[0018] S2. Place A2O3, La2O3 and Al2O3 into a mixer and mix them evenly. Then compress the mixture into tablets to obtain cakes.

[0019] S3. First, put ThO2 raw material into the bottom of the iridium crucible, then put in the cake material. Replace the air in the single crystal furnace completely with high-purity nitrogen, inert gas, nitrogen containing a small amount of hydrogen, or inert gas containing a small amount of hydrogen. Use medium-frequency induction heating, use LaAlO3 crystal as seed crystal, and grow it by the Czochralski method to obtain LaAlO3 crystal co-doped with rare earth ions and thorium ions.

[0020] Preferably, the process also includes step S4: after crystal growth is completed, the temperature is slowly reduced to room temperature at a rate of 10~60℃ / h, and the grown crystal is annealed in a reducing atmosphere at a temperature of 1200~1500℃ for 10~30 hours.

[0021] Preferably, the growth conditions of the Czochralski method are as follows: the crystal furnace is heated to 2100℃, the crystal pulling speed is 0.5~3mm / h, and the rotation speed is 3~15r / min; LaAlO3 crystals co-doped with rare earth ions and thorium ions are obtained by growing according to the procedure of crystal introduction, necking, shoulder formation, equal diameter, and tailing.

[0022] Furthermore, the present invention also provides the use of a rare earth ion and thorium ion co-doped LaAlO3 laser crystal as a gain medium for a pulsed laser.

[0023] Compared with the prior art, the technical effects of the present invention are as follows:

[0024] (1) The present invention uses the method of co-doping with rare earth ions and thorium ions to single-domain LaAlO3 crystal, and obtains LaAlO3 laser crystal with no scattering optical path along the single domain direction, which can obtain stable laser output;

[0025] (2) In this invention, the LaAlO3 crystal has low phonon energy. Using LaAlO3 crystal as the matrix, the doped rare earth ions can achieve a long fluorescence lifetime. For example, the fluorescence lifetime of Nd in the LaAlO3 crystal co-doped with 1 at.% Nd and 0.4 at.% Th is as long as 317. It is currently the longest Nd-doped laser crystal;

[0026] (3) In this invention, the LaAlO3 crystal has a large thermal conductivity (13.6). This can increase the repetition frequency of the output laser. Attached Figure Description

[0027] Figure 1 It is the absorption and emission cross section of a LaAlO3 crystal co-doped with 1 at. % Nd and 0.4 at. % Th;

[0028] Figure 2 The fluorescence lifetime of a LaAlO3 crystal co-doped with 1 at. % Nd and 0.4 at. % Th is shown.

[0029] Figure 3 This is a schematic diagram of a laser device for a LaAlO3 crystal co-doped with 1 at.% Nd and 0.4 at.% Th. Detailed Implementation

[0030] The specific implementation schemes of this invention patent will be described in detail below with examples:

[0031] Example 1

[0032] Application of 1 at. % Nd and 0.4 at. % Th co-doped LaAlO3 crystals in laser devices. Commercially available Nd₂O₃, Al₂O₃, La₂O₃, and ThO₂ with a purity of 5N were selected as raw materials, and the Nd₂O₃ was co-doped with 0.4 at. % Th. 0.01 Th 0.004 La 0.9847 The chemical formula for AlO3 was prepared by first mixing Nd₂O₃, La₂O₃, and Al₂O₃ in a mixer for at least 12 hours until the raw materials were uniformly mixed. Then, a hydraulic press was used to press the mixture into cylindrical cakes under a pressure of 5 GPa. ThO₂ raw material was placed at the bottom of an iridium crucible, followed by the cake. High-purity nitrogen was introduced to replace the air in the furnace. A Czochralski growth process was used to grow LaAlO₃ crystals co-doped with 1 at.% Nd and 0.4 at.% Th. The grown crystals exhibited a single-domain structure with no scattering effect in the light-transmitting direction, enabling stable laser output. (Appendix) Figure 1 The images show the absorption cross-section (a) and emission cross-section (b) of the crystal. The crystal achieves a maximum absorption cross-section at 798.7 nm and a maximum emission cross-section of 3.65 × 10⁻⁶ nm at 1080 nm. -20 cm 2 Appendix Figure 2 The fluorescence lifetime of this crystal is as long as 317.7 seconds. It is currently the longest oxide laser crystal. The crystal has a thermal conductivity of 13.6. Long fluorescence lifetimes in lasers are beneficial for energy storage, high thermal conductivity helps improve the repetition rate performance of lasers, and a suitable emission cross-section facilitates energy extraction. Considering all these factors, Nd and Th co-doped LaAlO3 laser crystals show significant promise for applications in high-repetition-rate, high-energy pulsed lasers.

[0033] A method for realizing infrared lasers using a LaAlO3 crystal co-doped with 1 at.% Nd and 0.4 at.% Th, with the experimental setup shown in the attached diagram. Figure 3 As shown, the system consists of a pump source 1, a laser focusing system 2, an input mirror 3, a crystal 4, and an output mirror 5 arranged coaxially, with 6 representing the output laser. The pump light is excited by a 799 nm LD pump source. The laser focusing system comprises two plano-convex lenses with a focal length of 50 mm and a distance of 50 mm between them. The input mirror 3 is a flat mirror with a 799 nm high-transmittance dielectric film and a 1080 nm high-reflectance dielectric film coated on its light-transmitting end face. The crystal is a LaAlO3 crystal co-doped with 1 at.% Nd and 0.4 at.% Th, with an effective Nd ion segregation rate of 0.98, a light transmission length of 5 mm, and a light transmission surface of 3 × 3 mm. 2 The cavity mirror is square; the output mirror is coated with a 799nm high-reflectivity dielectric film and a 1080nm partially transparent dielectric film, with a transmittance of 1~10%, preferably a dielectric film with a transmittance of 5%. Adding a saturable absorber inside the cavity mirror can achieve pulsed laser output.

[0034] This example discloses a LaAlO3 crystal co-doped with 1 at.% Nd and 0.4 at.% Th, which enables continuous, pulsed output of 1080 nm laser light.

[0035] Example 2

[0036] Application of 5 at. % Nd and 5 at. % Th co-doped LaAlO3 crystals in laser devices. Commercially available Nd₂O₃, Al₂O₃, La₂O₃, and ThO₂ with a purity of 5N were selected as raw materials, and the Nd₂O₃ was co-doped with 5 at. % Th. 0.05 Th 0.05 La 0.8833The chemical formula for AlO3 is prepared by first mixing Nd2O3, La2O3, and Al2O3 in a mixer for at least 12 hours until the raw materials are uniformly mixed. Then, a hydraulic press is used to press the mixture into a cylindrical cake under a pressure of 5 GPa. ThO2 raw material is placed at the bottom of an iridium crucible, followed by the cake. High-purity nitrogen is introduced to replace the air in the furnace. A Czochralski growth process is used to grow LaAlO3 crystals co-doped with 5 at.% Nd and 5 at.% Th. A method for realizing infrared lasers using 5 at.% Nd and 5 at.% Th co-doped LaAlO3 crystals is described, with the experimental setup shown in the attached diagram. Figure 3 As shown, the pump source 1, laser focusing system 2, input mirror 3, crystal 4, and output mirror 5 are arranged coaxially, and 6 is the output laser. The pump light is excited by a 799 nm LD pump source. The laser focusing system consists of two plano-convex lenses with a focal length of 50 mm and a distance of 50 mm between them. The input mirror 3 is a flat mirror with a 799 nm high-transmittance dielectric film and a 1080 nm high-reflectance dielectric film coated on its light-transmitting end face. The crystal is a 5 at.% Nd and 5 at.% Th co-doped LaAlO3 crystal with a light-transmitting length of 3 mm and a light-transmitting surface of 3 × 3 mm. 2 The crystal is square; both ends of the crystal are coated with antireflective films; the output mirror is coated with a 799 nm high-reflectivity dielectric film and a 1080 nm partially transparent dielectric film, with a transmittance of 1~10%, preferably a dielectric film with a transmittance of 6%. Adding a saturable absorber inside the cavity mirror can achieve pulsed laser output.

[0037] Example 3

[0038] Application of 0.1 at. % Nd and 0.2 at. % Th co-doped LaAlO3 crystals in laser devices. Commercially available Nd₂O₃, Al₂O₃, La₂O₃, and ThO₂ with a purity of 5N were selected as raw materials, and the Nd₂O₃ was co-doped with 0.1 at. % Nd and 0.2 at. % Th. 0.001 Th 0.002 La 0.9963 The chemical formula for AlO3 is prepared by first mixing Nd2O3, La2O3, and Al2O3 in a mixer for at least 12 hours until the raw materials are uniformly mixed. Then, a hydraulic press is used to press the mixture into cylindrical cakes under a pressure of 5 GPa. ThO2 raw material is placed at the bottom of an iridium crucible, followed by the cake. High-purity nitrogen is introduced to replace the air in the furnace. A Czochralski growth process is used to grow LaAlO3 crystals co-doped with 0.1 at.% Nd and 0.2 at.% Th. A method for realizing infrared lasers using 0.1 at.% Nd and 0.2 at.% Th co-doped LaAlO3 crystals is described, with the experimental setup attached. Figure 3As shown, the pump source 1, laser focusing system 2, input mirror 3, crystal 4, and output mirror 5 are arranged coaxially, and 6 is the output laser. The pump light is excited by a 799 nm LD pump source. The laser focusing system consists of two plano-convex lenses with a focal length of 50 mm and a distance of 50 mm between them. The input mirror 3 is a flat mirror with a 799 nm high-transmittance dielectric film and a 1080 nm high-reflectance dielectric film coated on its light-transmitting end face. The crystal is a LaAlO3 crystal co-doped with 0.1 at.% Nd and 0.2 at.% Th, with a light-transmitting length of 10 mm and a light-transmitting surface of 3×3 mm. 2 The crystal is square; both ends of the crystal are coated with antireflective films; the output mirror is coated with a 799 nm high-reflectivity dielectric film and a 1080 nm partially transparent dielectric film, with a transmittance of 1~10%, preferably a dielectric film with a transmittance of 1%. Adding a saturable absorber inside the cavity mirror can achieve pulsed laser output.

[0039] Example 4

[0040] Application of 1 at. %Yb and 0.4 at. %Th co-doped LaAlO3 crystals in laser devices. Commercially available Yb₂O₃, Al₂O₃, La₂O₃, and ThO₂ with a purity of 5N were selected as raw materials, and the process was carried out according to Yb... 0.01 Th 0.004 La 0.9847 The chemical formula for AlO3 is prepared by first mixing Yb₂O₃, La₂O₃, and Al₂O₃ in a mixer for at least 12 hours until the raw materials are uniformly mixed. Then, a hydraulic press is used to press the mixture into cylindrical cakes under a pressure of 5 GPa. ThO₂ raw material is placed at the bottom of an iridium crucible, followed by the cake. High-purity nitrogen is introduced to replace the air in the furnace. A LaAlO₃ crystal with 1 at.% Yb and 0.4 at.% Th co-doped is grown using the Czochralski method. A method for achieving infrared laser emission from a LaAlO₃ crystal with 1 at.% Yb and 0.4 at.% Th co-doped is also presented, with an experimental setup similar to the one described above. Figure 3 As shown, the system consists of a pump source 1, a laser focusing system 2, an input mirror 3, a crystal 4, and an output mirror 5 arranged coaxially, with 6 representing the output laser. The pump light is excited by a 970 nm LD pump source. The laser focusing system comprises two plano-convex lenses with a focal length of 50 mm and a distance of 50 mm between them. The input mirror 3 is a flat mirror with a high-transmittance dielectric film of 900-980 nm and a high-reflectance dielectric film of 1000-1100 nm coated on its light-transmitting end face. The crystal is a LaAlO3 crystal co-doped with 1 at.% Yb and 0.4 at.% Th, with a light-transmitting length of 5 mm and a light-transmitting surface of 4×4 mm. 2The device is square; the output mirror is coated with a dielectric film that allows partial transmission of 1000-1100 nm, with a transmittance of 1-10%, preferably 3%. Tuned laser output can be achieved by adding tuning elements (prisms, etc.) to the cavity mirror, and by adding a saturable absorber Cr... 4+ (e.g., YAG) can achieve ultrashort pulse laser output.

[0041] Example 5

[0042] Application of 5 at. %Yb and 5 at. %Th co-doped LaAlO3 crystals in laser devices. Commercially available Yb₂O₃, Al₂O₃, La₂O₃, and ThO₂ with a purity of 5N were selected as raw materials, and the process was carried out according to Yb... 0.05 Th 0.05 La 0.8833 The chemical formula for AlO3 is prepared by first mixing Yb₂O₃, La₂O₃, and Al₂O₃ in a mixer for at least 12 hours until the raw materials are uniformly mixed. Then, a hydraulic press is used to press the mixture into cylindrical cakes under a pressure of 5 GPa. ThO₂ raw material is placed at the bottom of an iridium crucible, followed by the cakes. High-purity nitrogen is introduced to replace the air in the furnace. A Czochralski growth process is used to grow LaAlO₃ crystals co-doped with 5 at.% Yb and 5 at.% Th. A method for achieving infrared laser effects using 5 at.% Yb and 5 at.% Th co-doped LaAlO₃ crystals is also described, with an experimental setup similar to the attached diagram. Figure 3 As shown, the system consists of a pump source 1, a laser focusing system 2, an input mirror 3, a crystal 4, and an output mirror 5 arranged coaxially, with 6 representing the output laser. The pump light is excited by a 970 nm LD pump source. The laser focusing system comprises two plano-convex lenses with a focal length of 50 mm and a distance of 50 mm between them. The input mirror 3 is a flat mirror with a high-transmittance dielectric film of 900-980 nm and a high-reflectivity dielectric film of 1000-1100 nm coated on its light-transmitting end face. The crystal is a 5 at.% Yb and 5 at.% Th co-doped LaAlO3 crystal with a light-transmitting length of 3 mm and a light-transmitting surface of 3 × 3 mm. 2 The device is square; the output mirror is coated with a dielectric film that allows partial transmission of 1000-1100 nm, with a transmittance of 1-10%, preferably 6%. Tuned laser output can be achieved by adding tuning elements (prisms, etc.) to the cavity mirror, and by adding a saturable absorber Cr... 4+ (e.g., YAG) can achieve ultrashort pulse laser output.

[0043] Example 6

[0044] Application of 5 at. %Tm and 5 at. %Th co-doped LaAlO3 crystals in laser devices. Commercially available 5N purity Tm2O3, Al2O3, La2O3, and ThO2 were selected as raw materials, and the crystals were processed according to Tm... 0.05 Th 0.05 La 0.8833 The chemical formula for AlO3 is prepared by first mixing Tm2O3, La2O3, and Al2O3 in a mixer for at least 12 hours until the raw materials are uniformly mixed. Then, a hydraulic press is used to press the mixture into cylindrical cakes under a pressure of 0.5-5 GPa. ThO2 raw material is placed at the bottom of an iridium crucible, followed by the cake. High-purity nitrogen is introduced to replace the air in the furnace. A Czochralski growth process is used to grow LaAlO3 crystals co-doped with 5 at.% Tm and 5 at.% Th. A method for achieving infrared laser effects using 5 at.% Tm and 5 at.% Th co-doped LaAlO3 crystals is also presented, with an experimental setup similar to the attached diagram. Figure 3 As shown, the system consists of a pump source 1, a laser focusing system 2, an input mirror 3, a crystal 4, and an output mirror 5 arranged coaxially, with 6 representing the output laser. The pump light is excited by a 793 nm LD pump source. The laser focusing system consists of two plano-convex lenses with a focal length of 50 mm and a distance of 50 mm between them. The input mirror 3 is a flat mirror with a high-transmittance dielectric film of 750-850 nm and a high-reflectance dielectric film of 1900-2100 nm coated on its light-transmitting end face. The crystal is a LaAlO3 crystal co-doped with 5 at. % Tm and 5 at. % Th, with a light-transmitting length of 3 mm and a light-transmitting surface of 3 × 3 mm. 2 The device is square; the output mirror is coated with a dielectric film that allows partial transmission of 1900-2100nm, with a transmittance of 1~10%, preferably a dielectric film with a transmittance of 5%. Adding tuning elements (prisms, etc.) to the cavity mirror enables tuned laser output, and adding a saturable absorber (graphene, etc.) enables ultrashort pulse laser output.

[0045] Example 7

[0046] Application of 1 at. %Tm and 0.4 at. %Th co-doped LaAlO3 crystals in laser devices. Commercially available 5N purity Tm2O3, Al2O3, La2O3, and ThO2 were selected as raw materials, and the crystals were processed according to Tm... 0.01 Th 0.004 La 0.9847The chemical formula for AlO3 is prepared by first mixing Tm2O3, La2O3, and Al2O3 in a mixer for at least 12 hours until the raw materials are uniformly mixed. Then, a hydraulic press is used to press the mixture into cylindrical cakes under a pressure of 5 GPa. ThO2 raw material is placed at the bottom of an iridium crucible, followed by the cakes. High-purity nitrogen is introduced to replace the air in the furnace. A LaAlO3 crystal with 1 at.% Tm and 0.4 at.% Th co-doped is grown using the Czochralski method. A method for achieving infrared laser emission from a LaAlO3 crystal with 1 at.% Tm and 0.4 at.% Th co-doped is also presented, with an experimental setup similar to the one described above. Figure 3 As shown, the system consists of a pump source 1, a laser focusing system 2, an input mirror 3, a crystal 4, and an output mirror 5 arranged coaxially, with 6 representing the output laser. The pump light is excited by a Tm:YLF laser. The laser focusing system consists of two plano-convex lenses with a focal length of 50 mm and a distance of 50 mm between them. The input mirror 3 is a flat mirror with a high-transmittance dielectric film of 750-850 nm and a high-reflectance dielectric film of 1900-2100 nm coated on its light-transmitting end face. The crystal is a LaAlO3 crystal co-doped with 1 at. % Tm and 0.4 at. % Th, with a light-transmitting length of 5 mm and a light-transmitting surface of 3×3 mm. 2 The device is square; the output mirror is coated with a dielectric film that allows partial transmission of 1900-2100nm, with a transmittance of 1~10%, preferably 4%. Adding tuning elements (prisms, etc.) to the cavity mirror enables tuned laser output, and adding a saturable absorber (graphene, etc.) enables ultrashort pulse laser output.

[0047] Example 8

[0048] Application of 1 at. %Ho and 0.4 at. %Th co-doped LaAlO3 crystals in laser devices. Commercially available Ho₂O₃, Al₂O₃, La₂O₃, and ThO₂ with a purity of 5N were selected as raw materials, and Ho₂O₃ was co-doped with 0.4 at. %Th. 0.01 Th 0.004 La 0.9847The chemical formula for AlO3 is prepared by first mixing Ho2O3, La2O3, and Al2O3 in a mixer for at least 12 hours until the raw materials are uniformly mixed. Then, a hydraulic press is used to press the mixture into cylindrical cakes under a pressure of 5 GPa. ThO2 raw material is placed at the bottom of an iridium crucible, followed by the cake. High-purity nitrogen is introduced to replace the air in the furnace. A LaAlO3 crystal with 1 at.% Ho and 0.4 at.% Th co-doped is grown using the Czochralski method. A method for realizing infrared lasers from the 1 at.% Ho and 0.4 at.% Th co-doped LaAlO3 crystal is also presented. The experimental setup mainly includes a pump source and a resonant cavity; the pump light is excited by a Tm:YLF laser; and a 1.9 μm mirror is deposited in the resonant cavity. Antireflective dielectric membrane and 2.1 High-reflectivity dielectric film, output mirror coated with 2.1 The dielectric film is partially permeable, with a transmittance ranging from 1% to 10%, preferably 4%. The crystal is a LaAlO3 crystal co-doped with 1 at.% Ho and 0.4 at.% Th, with a light transmission length of 5 mm and a light transmission surface of 3 × 3 mm. 2 The device is square. Adding a tuning element to the cavity mirror can achieve tuned laser output, and adding a saturable absorber (graphene, etc.) can achieve ultrashort pulse laser output.

[0049] Example 9

[0050] Application of 5 at. %Ho and 5 at. %Th co-doped LaAlO3 crystals in laser devices. Commercially available Er2O3, Al2O3, La2O3, and ThO2 with a purity of 5N were selected as raw materials, and Ho was used as the co-doped laAlO3 crystals. 0.05 Th 0.05 La 0.9847 The chemical formula for AlO3 was prepared by first mixing Er2O3, La2O3, and Al2O3 in a mixer for at least 12 hours until the raw materials were uniformly mixed. Then, a hydraulic press was used to press the mixture into cylindrical cakes under a pressure of 5 GPa. ThO2 raw materials were placed at the bottom of an iridium crucible, followed by the cakes. High-purity nitrogen was introduced to replace the air in the furnace. A Czochralski growth process was used to grow LaAlO3 crystals co-doped with 5 at.% Ho and 5 at.% Th. A method for realizing infrared lasers from 5 at.% Ho and 5 at.% Th co-doped LaAlO3 crystals was also presented. The experimental setup mainly included a pump source and a resonant cavity; the pump light was excited by a Tm:YLF laser; and a 1.9 μm mirror was deposited in the resonant cavity. Antireflective dielectric membrane and 2.1 High-reflectivity dielectric film, output mirror coated with 2.1 The dielectric film is partially permeable, with a transmittance ranging from 1% to 10%, preferably 5%. The crystal is a LaAlO3 crystal co-doped with 1 at.% Ho and 0.4 at.% Th, with a light transmission length of 3 mm and a light transmission surface of 3 × 3 mm. 2 The device is square. Adding a tuning element to the cavity mirror can achieve tuned laser output, and adding a saturable absorber (graphene, etc.) can achieve ultrashort pulse laser output.

[0051] Example 10

[0052] Application of 1 at. %Er and 0.4 at. %Th co-doped LaAlO3 crystals in laser devices. Commercially available Er₂O₃, Al₂O₃, La₂O₃, and ThO₂ with a purity of 5N were selected as raw materials. According to Er... 0.01 Th 0.004 La 0.8833 The chemical formula for AlO3 is prepared by first mixing Er2O3, La2O3, and Al2O3 in a mixer for at least 12 hours until the raw materials are uniformly mixed. Then, a hydraulic press is used to press the mixture into cylindrical cakes under a pressure of 5 GPa. ThO2 raw material is placed at the bottom of an iridium crucible, followed by the cake. High-purity nitrogen is introduced to replace the air in the furnace. A Czochralski growth process is used to grow LaAlO3 crystals co-doped with 1 at.% Er and 0.4 at.% Th. A method for achieving infrared laser effects using 1 at.% Er and 0.4 at.% Th co-doped LaAlO3 crystals is also described, with an experimental setup similar to the attached diagram. Figure 3 As shown, the pump source 1, laser focusing system 2, input mirror 3, crystal 4, and output mirror 5 are arranged coaxially, and 6 is the output laser. The pump light is excited by an LD laser with a wavelength between 600 and 800 nm. The laser focusing system consists of two plano-convex lenses with a focal length of 50 mm and a distance of 50 mm between them. The input mirror 3 is a flat mirror with a high-transmittance dielectric film of 600-800 nm and a high-reflectance dielectric film of 2940 nm coated on its light-transmitting end face. The crystal is a LaAlO3 crystal co-doped with 1 at. % Er and 0.4 at. % Th, with a light-transmitting length of 5 mm and a light-transmitting surface of 3×3 mm. 2 The square shape; the output mirror is coated with a dielectric film that allows partial transmission of 2940 nm, with a transmittance of 1~10%, preferably a dielectric film with a transmittance of 1%.

Claims

1. A rare-earth ion and thorium ion co-doped LaAlO3 laser crystal, characterized in that: The molecular formula of this crystal is: A x Th y La (1-x-1.33y) AlO3, where A is a trivalent rare earth ion, 0.001≤x≤0.05, 0<y≤0.05; A is Nd 3+ Yb 3+ Er 3+ Ho 3+ or Tm 3 Trivalent rare earth ions.

2. The LaAlO3 laser crystal co-doped with rare earth ions and thorium ions according to claim 1, characterized in that, The concentration range of trivalent rare earth ions doping is: 0.0025≤x≤0.015; the range of doped thorium ions is: 0.002≤y≤0.

02.

3. The LaAlO3 laser crystal co-doped with rare earth ions and thorium ions according to claim 2, characterized in that: Trivalent rare earth ion doping concentration: x=0.01; doped thorium ion concentration: y=0.

004.

4. The LaAlO3 laser crystal co-doped with rare earth ions and thorium ions according to any one of claims 1-3, characterized in that, The crystal belongs to the monoclinic crystal system, with space group R-3c and cell parameters a=0.537, b=0.537, c=13.

24. It has a pseudocubic structure at room temperature and phonon energy less than [missing value]. .

5. The LaAlO3 laser crystal co-doped with rare earth ions and thorium ions according to any one of claims 1-3, characterized in that, The fluorescence lifetime of the crystal is not less than 317.

7. .

6. A method for preparing a LaAlO3 laser crystal co-doped with rare earth ions and thorium ions as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Weigh the raw materials, including A2O3, Al2O3, La2O3, and ThO2, all with a purity greater than 99.999%, according to the molar ratio of each substance in the molecular formula. S2. Place A2O3, La2O3 and Al2O3 into a mixer and mix them evenly. Then compress the mixture into tablets to obtain cakes. S3. First, put ThO2 raw material into the bottom of the iridium crucible, then put in the cake material. Completely replace the air in the single crystal furnace with high-purity nitrogen or inert gas. Use medium-frequency induction heating, use LaAlO3 crystal as seed crystal, and grow it by the Czochralski method to obtain LaAlO3 crystal co-doped with rare earth ions and thorium ions.

7. The method for preparing a rare-earth ion and thorium ion co-doped LaAlO3 laser crystal according to claim 6, characterized in that, It also includes S4. After the crystal growth is completed, the temperature is slowly reduced to room temperature at a rate of 10~60℃ / h, and the grown crystal is annealed in a reducing atmosphere at a temperature of 1200~1500℃ for 10~30 hours.

8. The method for preparing a rare-earth ion and thorium ion co-doped LaAlO3 laser crystal according to claim 6 or 7, characterized in that, The aforementioned Czochralski growth method involves heating the crystal furnace to 2100℃, a crystal pulling speed of 0.5~3mm / h, and a rotation speed of 3~15r / min. Rare earth ion and thorium ion co-doped LaAlO3 crystals are obtained by following the procedure of crystal introduction, necking, shoulder formation, equal diameter formation, and tailing.

9. The use of a LaAlO3 laser crystal co-doped with rare earth ions and thorium ions as described in any one of claims 1-4 as a gain medium for a pulsed laser.

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