Fabrication and properties of multistage gradient doping Yb:YAG laser ceramics

Abstract

In order to fully pump and smoothen the temperature gradient of the gain medium, multistage gradient doping Yb:YAG laser ceramics were designed. The composite green bodies were fabricated by tape casting, and multistage gradient doping Yb:YAG ceramics with high optical quality were prepared by vacuum sintering and hot isostatic pressing. For samples pre‐sintered at 1740°C for 30 h and then HIP‐ed at 1700°C for 3 h in argon at 200 MPa, the in‐line transmission values at 1100 nm of YAG, 0.6 at.%Yb:YAG, and 1.5 at.%Yb:YAG ceramics were found to be 83.9%, 84.1%, and 83.3%, respectively. Finally, the 940 nm laser diode was used as the pump source to realize the 1030 nm laser output of multistage gradient doping Yb:YAG ceramic slab with a total energy of 3.43 J. The corresponding optical‐to‐optical conversion and slope efficiencies were 30% and 45%.

Fabrication and properties of novel composite laser ceramics with a surface‐gain structure

“…Casting parameters were adjusted, and casting tapes were prepared by a tape casting mechanism, according to our earlier work. 40,41 After drying for 24 h, the casting tapes were cut to the designed shapes and laminated to prepare the green bodies. According to the designed surface-gain structure, casting tapes with different components were laminated.…”

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

“…7,32 For Yb 3+ -doped laser gain media, unfortunately, Yb 2+ ions tended to be formed in combination with oxygen vacancies when the ceramics were fabricated in a reducible environment and especially when some tetravalent sintering aids were used, which would cause strong light absorption in the ultraviolet and visible region. [33][34][35] 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.…”

“…Moreover, rare‐earth doped ions of transparent ceramics are usually not in the valence that meets the application requirements so the ceramics need to be annealed under a suitable atmosphere 7,32 . For Yb 3+ ‐doped laser gain media, unfortunately, Yb 2+ ions tended to be formed in combination with oxygen vacancies when the ceramics were fabricated in a reducible environment and especially when some tetravalent sintering aids were used, which would cause strong light absorption in the ultraviolet and visible region 33–35 . 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.…”