Recently, a research team led by Prof. LI Jiang from Shanghai Institute of Ceramics of the Chinese Academy of Sciences has made much progress in the study of Yb:YSAG laser ceramics.

The researchers prepared 10 at.% Yb: Y₃ScAl₄O₁₂ laser ceramics by solid state reaction sintering and hot isostatic pressing (HIP) technology, and realized the high efficiency laser output of Yb:Y₃ScAl₄O₁₂ ceramics. Using the 929.4nm fiber coupled laser diode (LD) pumping, Quasi Continuous-Wave (QCW) laser output with slope efficiency and output power achieved 67.6% and 11.3W (the maximum reported laser output power for this material at present) respectively.

Besides, they studied the influence of Yb³⁺ doping concentration on the microstructure and optical property of Yb:Y₃ScAl₄O₁₂ laser ceramics, as well as the influence of different Sc³⁺ contents on the property of 10 at.% Yb:Y₃Sc_xAl_5-xO₁₂ ceramics. The 10 at.% Yb:Y₃ScAl₄O₁₂ laser ceramics showed the best optical quality and laser performance. With the increase of Sc³⁺ content, the full width of half maximum (FWHM) of Yb³⁺ emission peak increases correspondingly.

By testing the laser performance of 10 at.% Yb:Y₃Sc_1.5Al_3.5O₁₂ transparent ceramics, the researchers found that a QCW laser output power of 10.8W with the corresponding slope efficiency of 66.4%, and the tunable laser wavelength range was 86.2nm (988-1074.2nm). It is the largest laser tuning range ever reported for Yb:YSAG ceramics.

In addition, collaborating with Prof. LI Wenxue from East China Normal University, the researchers realized the high-efficiency continuous laser output of the 10 at.% Yb:Y₃Sc_1.5Al_3.5O₁₂ ceramics by using plano-plano laser resonator and three-mirror laser resonator.

They also prepared high-quality 4 at.% Tm:Y₃ScAl₄O₁₂ transparent ceramics by vacuum sintering, and achieved the first 2μm laser output of this new ceramic material through a 790nm fiber coupled LD pumping. The laser wavelength was 2015nm, and the maximum laser output power was 0.54W, whose corresponding slope efficiency is 4.8%.

Yb: YSAG laser ceramics are mainly used for 1μm laser generation. The 2 μm mid infrared laser is a very important laser source. Tm³⁺ ion is a commonly used active ion in 2μ m mid infrared laser. Compared with Tm:YAG ceramic, Tm:YSAG ceramics have a longer fluorescence life time, which is suitable for energy storage, and are are promising gain media for mid infrared laser.