Resonantly pumped eye-safe Er³⁺:YAG SPS-HIP ceramic laser

Transparent polycrystalline ceramics are increasingly used in laser applications due to their potential for high optical quality and ease of fabrication. Prior research has shown that Er³⁺:YAG ceramics can support laser action, but challenges remain in achieving high efficiency and transparency at scale. No prior work had resolved the optimal combination of sintering and post-treatment methods to produce large-scale Er³⁺:YAG ceramics suitable for laser operation. This gap motivated the exploration of new fabrication techniques to improve laser performance. Spark plasma sintering has been proposed as a method to produce dense ceramics with minimal grain boundary scattering. However, its effectiveness in Er³⁺:YAG systems had not been fully demonstrated. The need for a scalable and efficient laser material led to the investigation of a two-step process combining sintering with hot isostatic pressing. This uncertainty drove the current study to evaluate the feasibility of resonant pumping in such ceramics. The goal was to determine whether this approach could yield improved optical and laser properties.

The aim of this study was to develop and characterize a large-scale transparent Er³⁺:YAG ceramic suitable for resonant laser pumping. The specific problem addressed was the lack of high-efficiency laser ceramics fabricated using scalable methods. The motivation stemmed from the demand for eye-safe laser sources in industrial and medical applications. The researchers proposed that combining spark plasma sintering with HIP post-treatment could enhance ceramic transparency and laser performance. This approach was chosen to overcome the limitations of traditional sintering techniques. The study focused on evaluating the microstructure, spectroscopic properties, and laser output of the fabricated ceramic. By analyzing these parameters, the researchers aimed to determine the potential of the material for practical laser systems. The ultimate goal was to establish a reproducible fabrication method for high-performance Er³⁺:YAG laser ceramics.

The study employed a two-step fabrication process involving spark plasma sintering followed by hot isostatic pressing. This method was selected to achieve high-density and transparent ceramic samples. The Er³⁺:YAG powder was first sintered using spark plasma sintering to form a green body. The resulting ceramic was then subjected to HIP treatment to reduce porosity and improve optical quality. Microstructural analysis was conducted using scanning electron microscopy to assess grain size and distribution. Spectroscopic measurements included absorption and emission spectra to evaluate the material's optical properties. Laser performance was tested under resonant pumping conditions using a diode laser source. The output was measured in terms of slope efficiency and optical-optical conversion efficiency. These methods allowed the researchers to correlate structural and optical properties with laser performance.

The fabricated Er³⁺:YAG ceramic achieved a maximum slope efficiency of approximately 31%. The optical-optical efficiency reached 20% under resonant pumping conditions. These values suggest that the material is capable of efficient laser action. The microstructural analysis revealed a homogeneous grain structure with minimal porosity. Spectroscopic measurements indicated strong absorption in the pump band and efficient emission in the 2.9 μm region. The HIP post-treatment was found to significantly improve the ceramic's transparency and optical quality. No significant degradation in laser performance was observed over the tested range of pump powers. The results demonstrate the feasibility of using the two-step fabrication method for producing high-performance Er³⁺:YAG laser ceramics.

The study demonstrated that resonantly pumped Er³⁺:YAG ceramics can be produced using a two-step fabrication method. The combination of spark plasma sintering and HIP post-treatment yielded a transparent ceramic with high optical quality. The material achieved a slope efficiency of approximately 31% and an optical-optical efficiency of 20%. These findings suggest that the fabricated ceramic is suitable for eye-safe laser applications. The microstructural and spectroscopic analyses confirmed the material's suitability for laser operation. The results support the use of this fabrication approach for producing scalable Er³⁺:YAG laser ceramics. The authors propose that the method can be extended to other rare-earth-doped ceramics. The study provides a foundation for further development of high-efficiency laser materials.