Fabrication of high‐efficiency Yb:Y₂O₃ laser ceramics without photodarkening

Abstract

High-efficiency Yb:Y 2 O 3 laser ceramics were fabricated using the vacuumsintering plus hot isostatic pressing (HIP) without sintering additives. Highpurity well-dispersed nanocrystalline Yb:Y 2 O 3 powder was synthesized using a modified co-precipitation method in-house. The green bodies were first vacuum sintered at a temperature as low as 1430 • C and then HIPed at 1450 • C. Finally, the samples were air annealed at 800 • C for 10 h. Although no sintering aids were used, full density of the samples with excellent optical homogeneity and an inline transmission of 80% at 400 nm could be obtained. Moreover, photodarkening phenomenon was not detected in the ceramics. Preliminary laser experiment with the fabricated ceramics in a two-mirror cavity has demonstrated 32 W continuous-wave (CW) output at ∼1077 nm with an optical-to-optical conversion efficiency of 58.2%. To the best of our knowledge, this is so far the highest CW output power and optical-to-optical conversion efficiency achieved with the Yb 3+doped sesquioxide ceramics in a simple two-mirror cavity.

The origin of microstructural inhomogeneity in vacuum‐sintered ZrO2‐doped Lu2O3 transparent ceramics

“…The suitability of the ceramic fabrication process will be clearly reflected through the microstructure, such as residual porosity and grain size, which determines the transparency of ceramics. 10 Controlling microstructure development, especially preventing pore-boundary separation during final stage sintering is crucial for determining ceramic optical characteristics. 11 In order to achieve fully dense transparent polycrystalline ceramics, additional sintering additives are usually added during vacuum sintering, such as ZrO 2 , HfO 2 , TiO 2 , etc.…”

“…The suitability of the ceramic fabrication process will be clearly reflected through the microstructure, such as residual porosity and grain size, which determines the transparency of ceramics 10 . Controlling microstructure development, especially preventing pore‐boundary separation during final stage sintering is crucial for determining ceramic optical characteristics 11 .…”

Influence of annealing on microstructures and properties of Yb:Lu2O3 transparent ceramics

“…To reduce the adverse effects, various reports have focused on how to eliminate the oxygen vacancies or other color centers of gain media. 36,37 According to the above documents, the effect of the annealing conditions including temperature and holding time on the ceramic properties or microstructures was investigated based on the transparent ceramics with similar microstructures such as Y 3 Al 5 O 12 (YAG) or Y 2 O 3 -based materials.…”

“…Especially for 1 μm laser gain media used in high‐power or high‐energy laser operations, the formations of oxygen vacancies or color centers tend to cause the generation of excess heat in the matrix lattice, thus leading to the decline of laser performance or even to the damage of the gain media due to the non‐radiation transition. To reduce the adverse effects, various reports have focused on how to eliminate the oxygen vacancies or other color centers of gain media 36,37 . According to the above documents, the effect of the annealing conditions including temperature and holding time on the ceramic properties or microstructures was investigated based on the transparent ceramics with similar microstructures such as Y 3 Al 5 O 12 (YAG) or Y 2 O 3 ‐based materials.…”

Synthesis of MgO Coating Gd2O3 Nanopowders for Consolidating Gd2O3-MgO Nanocomposite with Homogenous Phase Domain Distribution and High Mid-Infrared Transparency

“…Transparent polycrystalline ceramics have attracted widespread attention due to their wide range of applications such as laser hosts, infrared windows/domes, and transparent armors, instead of their single-crystal counterparts, mainly due to their processing flexibility and low cost for fabricating items with large sizes and complex shapes [1][2][3]. In particular, transparent polycrystalline ceramics have great potential in the application of infrared windows because of their excellent optical and mechanical properties [4][5][6].…”