Yag-based composite laser ceramic and method for manufacturing the same

Abstract

This invention discloses a YAG-based composite laser ceramic and its preparation method. The composite laser ceramic has a five-layer structure from top to bottom: a microstructured concave YAG transparent ceramic, an Nd:YAG transparent ceramic, a YAG transparent ceramic I, a Ce,Nd:YAG transparent ceramic, and a YAG transparent ceramic II. The microstructured concave YAG transparent ceramic is used to reduce the temperature gradient and compensate for the thermal lensing effect; the Nd:YAG transparent ceramic is used to collect the energy emitted by the microstructured concave YAG transparent ceramic and to transfer the energy; the Ce,Nd:YAG transparent ceramic is used for laser energy transfer; and the YAG transparent ceramic I and YAG transparent ceramic II are used to reduce the ceramic thermal lensing effect. It is prepared using thermal bonding technology. The composite laser ceramic of this invention emits bright yellow light near 1064 nm when excited by a laser with a pump source of 808 nm. Furthermore, the composite laser ceramic has a light-to-light conversion efficiency of 19.85% and a laser threshold of 410 mW.

Description

Technical Field

[0001] This invention belongs to the field of ceramic materials and relates to the preparation of optical functional ceramics, specifically to a YAG-based composite laser ceramic and its preparation method. Background Technology

[0002] Transparent laser ceramics are a new type of laser material that has seen rapid development in recent years. Currently, the laser materials on the market are mainly yttrium aluminum garnet (YAG) single crystals and glass. YAG single crystals possess high thermal conductivity, chemical stability, and good workability, making them a widely used solid-state laser medium. However, due to limitations imposed by impurity segregation coefficients and size, they suffer from low output power and low luminous efficiency, hindering their application. Transparent YAG polycrystalline ceramics, on the other hand, offer advantages such as ease of manufacturing, low cost, large size, high doping concentration, high thermal conductivity, good thermal shock resistance, mass production capability, and ease of realizing multilayer and multifunctional ceramic structures. They can be used as a high-performance laser medium, thus compensating for the shortcomings of single crystals as laser working media, making them a highly promising new type of solid-state laser material.

[0003] In recent years, researchers have studied Ce,Nd:YAG crystals and transparent ceramics for direct-pumped solid-state lasers using solar energy. Ce ions, acting as sensitizers, can absorb photon energy in the ultraviolet spectral region and transfer that energy to Nd ions via non-radiative transitions. This energy transfer process not only increases spectral utilization but also reduces thermal deformation to some extent, resulting in higher laser energy output from Ce:Nd crystals compared to pure Nd crystals under the same pumping conditions. Furthermore, this energy transfer process also contributes to improved laser efficiency because the absorption and emission peaks of Ce ions in the YAG matrix match the absorption peaks of Nd ions, allowing for efficient energy transfer from Ce to Nd ions, thereby enhancing laser performance. In 2024, Payziyev et al. used a 3mm diameter composite YAG / Ce:Nd:YAG / YAG material rod. When the laser was at 900 W / m... 2 When exposed to 593W of incident solar power at an irradiance of [missing information], the laser rod achieved a multimode output power of 8.5W with a light-to-light conversion efficiency of 1.43%. The YAG / Ce:Nd:YAG / YAG composite laser rod withstood the harsh conditions of solar-pumped conditions for several hours without any negative impact or a decrease in laser output over time.

[0004] Currently, there are various methods for preparing laser gain media. These include a layered thermally conductive structure of erbium-ytterbium co-doped phosphate glass gain media based on thermal bonding technology (CN116706649A), multilayer YAG-Tm:YAG-YAG-Ho:YAG-YAG composite laser ceramics and their preparation methods and applications (CN104261831A), and a bonding method for rare-earth neodymium or ytterbium-doped YAG laser crystals (CN114592240A). The aim of these methods is to bond multiple layers of gain media together, reducing the internal temperature gradient and thus increasing the output power of the gain media. However, the bonding methods described in these patents still have shortcomings in both ceramic bonding and ceramic heat dissipation structures. Summary of the Invention

[0005] One objective of this invention is to provide a YAG-based composite laser ceramic, which, as a laser material, has the advantages of improving heat dissipation, mitigating thermal lensing effects, increasing laser output efficiency, and achieving high-energy laser output.

[0006] One of the objectives of this invention is to provide a method for preparing YAG-based composite laser ceramics that is easy to industrialize.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a YAG-based composite laser ceramic, which has a five-layer structure from top to bottom: a microstructured concave YAG transparent ceramic, an Nd:YAG transparent ceramic, a YAG transparent ceramic I, a Ce,Nd:YAG transparent ceramic, and a YAG transparent ceramic II. The microstructured concave YAG transparent ceramic is used to reduce the temperature gradient and compensate for the thermal lensing effect. The Nd:YAG transparent ceramic is used to collect the energy emitted by the microstructured concave YAG transparent ceramic and to transfer the energy. The Ce,Nd:YAG transparent ceramic has good optical transmittance and low scattering loss, and is used for laser energy transfer. The YAG transparent ceramic I and YAG transparent ceramic II are used to reduce the ceramic thermal lensing effect.

[0009] Preferably, the chemical formula of the Nd:YAG transparent ceramic is (Nd x Y 1-x Al5O 12 Where 0 < x ≤ 0.01; the chemical formula of the Ce,Nd:YAG transparent ceramic is (Ce y Nd z Y 1-y-z Al5O 12 , where 0 < y ≤ 0.006, 0.005 ≤ z ≤ 0.01.

[0010] Preferably, the thickness of the first, third, and fifth layers of the composite laser ceramic is 1.5 mm; and the thickness of the second and fourth layers is 2 mm.

[0011] The composite laser ceramic emits bright yellow light when excited by an 808nm laser diode solid-state laser, and its optical-to-optical conversion efficiency is 19.85% and its laser threshold is 410mW.

[0012] Secondly, the present invention also provides a method for preparing the YAG-based composite laser ceramic described in the first aspect, specifically including the following steps:

[0013] Step 1: Prepare YAG, Nd:YAG and Ce,Nd:YAG powders according to stoichiometric ratios;

[0014] Step 2: The powder is dry-pressed using appropriate molds to press concave YAG, YAG, Nd:YAG and Ce,Nd:YAG ceramic blanks respectively. The resulting ceramic blanks are then subjected to vacuum sintering and annealing treatment in sequence.

[0015] Step 3: Using thermal bonding technology, the ceramic end faces of each part are bonded together in concave YAG-Nd:YAG-YAG-Ce, Nd:YAG-YAG to form a composite laser ceramic. The thermal bonding technology involves first heating the pre-bonded ceramic to 1300-1400℃ and holding it at that temperature for 15-25 hours; then annealing the composite ceramic in a hydrogen atmosphere at a temperature of 1100-1300℃ for 15-25 hours.

[0016] Step 4: Deposit antireflective coatings at both ends of the composite laser ceramic.

[0017] Preferably, in step two, the concave YAG transparent ceramic obtained by dry pressing has a concave end depth of 0.2 to 0.6 mm.

[0018] Preferably, in step two, the vacuum sintering temperature is 1660℃~1700℃, and the holding time is 7~9h; the annealing temperature is 1400~1500℃, and the holding time is 8~12h.

[0019] Preferably, in step four, high-transmittance films of 808nm and 1064nm are deposited at both ends of the composite laser ceramic to reduce resonant cavity loss.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The composite laser ceramic of the present invention emits bright yellow light near 1064 nm when excited by a laser with a pump source of 808 nm. Moreover, the composite laser ceramic has an optical-to-optical conversion efficiency of 19.85% and a laser threshold of 410 mW.

[0022] (2) This invention fully utilizes the advantages of thermal bonding technology, successfully reducing the thermal lensing effect caused by thermal accumulation in the laser gain medium by improving the end-face damage of the thermally bonded crystal. Furthermore, the preparation method is simple, has a short preparation cycle, and is environmentally friendly, better meeting the needs of experimental development.

[0023] (3) The composite laser ceramic cross section prepared by the present invention is selected with concave YAG for heat dissipation treatment. The analysis of thermal focal length shows that the selected concave end face and thermal bonding technology effectively compensate for the thermal lens effect of the ceramic, and greatly protect the ceramic from laser damage and fracture. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the composite laser ceramic preform in this invention; in the figure: 1-concave YAG transparent ceramic; 2-Nd:YAG transparent ceramic; 3-YAG transparent ceramic I; 4-Ce,Nd:YAG transparent ceramic; 5-YAG transparent ceramic II;

[0025] Figure 2 The transmittance curves of the composite laser ceramics prepared in Examples 1-3 of this invention are shown.

[0026] Figure 3 The excitation spectra of transparent ceramics of YAG, 1 at.% Nd:YAG, 0.3 at.% Ce, and 1 at.% Nd:YAG at 1064 nm are shown.

[0027] Figure 4 This is a graph showing the relationship between the absorption power and the pump power of the composite laser ceramic prepared in Example 2 of this invention. Detailed Implementation

[0028] This invention provides a YAG-based composite laser ceramic, with the structure as follows: Figure 1 As shown, the composite laser ceramic has five layers from top to bottom: microstructured concave YAG transparent ceramic 1, Nd:YAG transparent ceramic 2, YAG transparent ceramic I 3, Ce,Nd:YAG transparent ceramic 4, and YAG transparent ceramic II 5. The microstructured concave YAG transparent ceramic 1 is used to reduce the temperature gradient and compensate for the thermal lensing effect. The Nd:YAG transparent ceramic 2 is used to collect the energy emitted by the microstructured concave YAG transparent ceramic and transfer the energy. The Ce,Nd:YAG transparent ceramic 4 has good optical transmittance and low scattering loss, and is used for laser energy transfer. The YAG transparent ceramic I 3 and YAG transparent ceramic II 5 are used to reduce the ceramic thermal lensing effect.

[0029] This invention also provides a method for preparing the above-mentioned YAG-based composite laser ceramic, specifically including the following steps:

[0030] Step 1: Prepare YAG, Nd:YAG and Ce,Nd:YAG powders according to stoichiometric ratios;

[0031] Step 2: The powder is dry-pressed using appropriate molds to press concave YAG, YAG, Nd:YAG and Ce,Nd:YAG ceramic blanks respectively. The resulting ceramic blanks are then subjected to vacuum sintering and annealing treatment in sequence.

[0032] Step 3: Using thermal bonding technology, the ceramic end faces of each part are bonded together in concave YAG-Nd:YAG-YAG-Ce, Nd:YAG-YAG to form a composite laser ceramic. The thermal bonding technology involves first heating the pre-bonded ceramic to 1300-1400℃ and holding it at that temperature for 15-25 hours; then annealing the composite ceramic in a hydrogen atmosphere at a temperature of 1100-1300℃ for 15-25 hours.

[0033] Step 4: Deposit antireflective coatings at both ends of the composite laser ceramic.

[0034] This invention, through the combination of thermal bonding technology and ceramic concave end face, can further improve the heat dissipation capacity of the gain medium and reduce the thermal lensing effect during the experiment, based on the original heat dissipation structure, thereby enabling the gain medium to achieve high-performance and stable laser output.

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0036] The raw material powders used in the following examples are all commercially available products with a purity greater than 99.9%.

[0037] Example 1: The five-layer structure of the prepared composite laser ceramic is as follows: concave YAG transparent ceramic 1, Nd:YAG transparent ceramic 2, YAG transparent ceramic 3, Ce,Nd:YAG transparent ceramic 4, and YAG transparent ceramic 5. The thickness of the first, third, and fifth layers is 1.5 mm; the thickness of the second and fourth layers is 2 mm.

[0038] Step 1: Prepare YAG, 0.5 at.% Nd:YAG and 0.1 at.% Ce, 0.5 at.% Nd:YAG powders according to the stoichiometric ratios;

[0039] Step 2: The powder is dry-pressed using appropriate molds to press concave YAG, YAG, Nd:YAG, and Ce,Nd:YAG ceramic blanks. For the concave YAG, a specific concave forming tool is required during pressing, with a concave end depth of 0.6mm. The resulting ceramic blanks are then subjected to vacuum sintering and annealing treatments. The vacuum sintering temperature is 1660℃, and the holding time is 9 hours; the annealing temperature is 1400℃, and the holding time is 12 hours.

[0040] Step 3: Using thermal bonding technology, the ceramic end faces of each part are bonded together in concave YAG-Nd:YAG-YAG-Ce, Nd:YAG-YAG format to form a composite laser ceramic. The thermal bonding technology involves first heating the pre-bonded ceramic to 1300℃ and holding it at that temperature for 25 hours; then annealing the composite ceramic in a hydrogen atmosphere at 1100℃ for 25 hours.

[0041] Step four: Deposit 808nm and 1064nm high-transmittance films at both ends of the composite laser ceramic to reduce resonant cavity loss.

[0042] The composite laser ceramic was excited by an 808nm laser diode solid-state laser. As the pump power gradually increased, its optical-to-optical conversion efficiency was 10.93% and the laser threshold was 750mW.

[0043] Example 2: The five-layer structure of the prepared composite laser ceramic is as follows: concave YAG transparent ceramic 1, Nd:YAG transparent ceramic 2, YAG transparent ceramic 3, Ce,Nd:YAG transparent ceramic 4, and YAG transparent ceramic 5. The thickness of the first, third, and fifth layers is 1.5 mm; the thickness of the second and fourth layers is 2 mm.

[0044] Step 1: Prepare YAG, 1 at.% Nd:YAG and 0.3 at.% Ce, 1 at.% Nd:YAG powders according to the stoichiometric ratios;

[0045] Step 2: The powder is dry-pressed using appropriate molds to press concave YAG, YAG, Nd:YAG, and Ce,Nd:YAG ceramic blanks. For the concave YAG, a specific concave forming tool is required during pressing, with a concave end depth of 0.4mm. The resulting ceramics are then subjected to vacuum sintering and annealing treatments. The vacuum sintering temperature is 1680℃, and the holding time is 8 hours; the annealing temperature is 1450℃, and the holding time is 10 hours.

[0046] Step 3: Using thermal bonding technology, the ceramic end faces of each part are bonded together in concave YAG-Nd:YAG-YAG-Ce, Nd:YAG-YAG format to form a composite laser ceramic. The thermal bonding technology involves first heating the pre-bonded ceramic to 1350℃ and holding it at that temperature for 20 hours; then annealing the composite ceramic in a hydrogen atmosphere at 1200℃ for 20 hours.

[0047] Step four: Deposit 808nm and 1064nm high-transmittance films at both ends of the composite laser ceramic to reduce resonant cavity loss.

[0048] A composite laser ceramic was excited using an 808nm laser diode solid-state laser. With increasing pump power, its optical-to-optical conversion efficiency reached 19.85%, and the laser threshold was 410mW. Figure 4 As shown.

[0049] Example 3: The five-layer structure of the prepared composite laser ceramic is as follows: concave YAG transparent ceramic 1, Nd:YAG transparent ceramic 2, YAG transparent ceramic 3, Ce,Nd:YAG transparent ceramic 4, and YAG transparent ceramic 5. The thickness of the first, third, and fifth layers is 1.5 mm; the thickness of the second and fourth layers is 2 mm.

[0050] Step 1: Prepare YAG, 0.1 at.% Nd:YAG and 0.6 at.% Ce, 0.7 at.% Nd:YAG powders according to the stoichiometric ratios;

[0051] Step 2: The powder is dry-pressed using appropriate molds to press concave YAG, YAG, Nd:YAG, and Ce,Nd:YAG ceramic blanks. For the concave YAG, a specific concave forming tool is required during pressing, with a concave end depth of 0.2mm. The resulting ceramics are then subjected to vacuum sintering and annealing treatments. The vacuum sintering temperature is 1700℃, and the holding time is 7 hours; the annealing temperature is 1500℃, and the holding time is 8 hours.

[0052] Step 3: Using thermal bonding technology, the ceramic end faces of each part are bonded together in concave YAG-Nd:YAG-YAG-Ce, Nd:YAG-YAG format to form a composite laser ceramic. The thermal bonding technology involves first heating the pre-bonded ceramic to 1400℃ and holding it at that temperature for 15 hours; then annealing the composite ceramic in a hydrogen atmosphere at 1300℃ for 15 hours.

[0053] Step four: Deposit 808nm and 1064nm high-transmittance films at both ends of the composite laser ceramic to reduce resonant cavity loss.

[0054] The composite laser ceramic was excited by an 808nm laser diode solid-state laser. As the pump power gradually increased, its optical-to-optical conversion efficiency was 15.62% and the laser threshold was 530mW.

[0055] Figure 2 The figures show the transmittance curves of the composite laser ceramics prepared in Examples 1-3 of this invention. As can be seen from the figures, all three composite ceramics exhibit good transmittance. The transmittance of the composite ceramic in Example 1 is 82.719, the transmittance of the composite ceramic in Example 2 is 82.803, and the transmittance of the composite ceramic in Example 3 is 80.765. The transmittance of all three composite ceramics is close to the theoretical transmittance of transparent ceramics, making them suitable for laser applications.

[0056] Figure 3 The excitation spectra of transparent ceramics containing YAG, 1 at.% Nd:YAG, 0.3 at.% Ce, and 1 at.% Nd:YAG at 1064 nm show that undoped Nd... 3+ No excitation peaks were observed in the ion-containing ceramic samples. In Ce,Nd;YAG ceramics, visible light in the 400nm-550nm band can be well excited to achieve 1064nm laser emission. Therefore, Ce,Nd;YAG ceramics can be used as gain media for solar-pumped lasers.

[0057] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing YAG-based composite laser ceramics, characterized in that, The composite laser ceramic has five layers from top to bottom: microstructured concave YAG transparent ceramic, Nd:YAG transparent ceramic, YAG transparent ceramic I, Ce,Nd:YAG transparent ceramic, and YAG transparent ceramic II; specifically, it includes the following steps: Step 1: Prepare YAG, Nd:YAG, and Ce,Nd:YAG powders according to stoichiometric ratios; the chemical formula of Nd:YAG is (Nd x Y 1-x Al5O 12 Where 0 < x ≤ 0.01; the chemical formula of the Ce,Nd:YAG is (Ce y Nd z Y 1-y-z Al5O 12 Where 0 < y ≤ 0.006, 0.005 ≤ z ≤ 0.01; Step 2: The powder is dry-pressed using appropriate molds to press concave YAG, YAG, Nd:YAG and Ce,Nd:YAG ceramic blanks respectively. The resulting ceramic blanks are then subjected to vacuum sintering and annealing treatment in sequence. Step 3: Using thermal bonding technology, the ceramic end faces of each part are bonded together in concave YAG-Nd:YAG-YAG-Ce, Nd:YAG-YAG to form a composite laser ceramic. The thermal bonding technology involves first heating the pre-bonded ceramic to 1300~1400°C and holding it at that temperature for 15~25 hours; then annealing the composite ceramic in a hydrogen atmosphere at a temperature of 1100~1300°C for 15~25 hours. Step 4: Deposit antireflective coatings at both ends of the composite laser ceramic.

2. The method for preparing YAG-based composite laser ceramics according to claim 1, characterized in that, In step two, the concave YAG transparent ceramic obtained by dry pressing has a concave end depth of 0.2~0.6mm.

3. The method for preparing YAG-based composite laser ceramics according to claim 1, characterized in that, In step two, the vacuum sintering temperature is 1660℃~1700℃, and the holding time is 7~9h; the annealing temperature is 1400~1500℃, and the holding time is 8~12h.

4. The method for preparing YAG-based composite laser ceramics according to claim 1, characterized in that, In step four, high-transmittance films of 808 nm and 1064 nm are deposited at both ends of the composite laser ceramic to reduce resonant cavity loss.

5. A YAG-based composite laser ceramic prepared by the preparation method according to any one of claims 1 to 4, characterized in that, The composite laser ceramic has a five-layer structure from top to bottom: a microstructured concave YAG transparent ceramic, an Nd:YAG transparent ceramic, a YAG transparent ceramic I, a Ce,Nd:YAG transparent ceramic, and a YAG transparent ceramic II. The microstructured concave YAG transparent ceramic is used to reduce the temperature gradient and compensate for the thermal lensing effect. The Nd:YAG transparent ceramic is used to collect the energy emitted by the microstructured concave YAG transparent ceramic and to transfer the energy. The Ce,Nd:YAG transparent ceramic is used for laser energy transfer. The YAG transparent ceramic I and YAG transparent ceramic II are used to reduce the ceramic thermal lensing effect.

6. The YAG-based composite laser ceramic according to claim 5, characterized in that, The first, third, and fifth layers of the composite laser ceramic have a thickness of 1.5 mm; the second and fourth layers have a thickness of 2 mm.

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