Fabrication of high quality Er: CaF2 transparent ceramic

Update time: 2020-09-05

Mid-infrared lasers have been widely used in various fields, such as imaging, detection, diagnostics, environmental monitoring, medicine, industry, defense, etc. For mid-infrared laser systems, low phonon energy gain materials are key factors.

Among these mid-infrared materials, Er3+-doped CaF2 transparent ceramics are promising candidate materials because of their ultra-low phonon energy as well as excellent physical, chemical, and optical properties, which quickly attract the attention of researchers. However, traditional preparation methods can’t obtain high-quality Er3+-doped CaF2 transparent ceramics.

Recently, a research team led by Professor Zhang Long from Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences has developed a high quality Er3+-doped CaF2 transparent ceramics by single crystal ceramization. Their study was published in Journal of the European Ceramic Society.

In this research, they grew the 3 at% Er3+-doped CaF2 single crystal by the temperature gradient technique (TGT). The single crystal was cut into 5*5*3 mm3 cuboid, and put into a graphite mold. The single crystal undergoes plastic deformation and hot-pressing sintering in a vacuum hot press furnace, after which Er3+-doped CaF2 transparent ceramic was obtained. The ceramic sample was polished to 1-mm for characterization.

They discovered that the Er3+-doped CaF2 transparent ceramics possess obvious polycrystalline structure, perfect transmittance, and excellent mid-infrared performance, which are better than that of hot-pressed and hot-formed Er3+-doped CaF2 ceramics.

In addition, the influencing factor for the slight change of Er3+-doped CaF2 transparent ceramics in optical performance was also discussed initially.

This work offers significant and wide-ranging opportunities for obtaining low phonon energy mid-infrared alkaline earth fluoride ceramic for future applications in mid-infrared lasers and amplifiers.

The in-line transmittance spectrum (thickness:1 mm) of the polished Er3+-doped CaF2 single crystal and Er3+-doped CaF2 ceramic. The inset shows the transparency of the Er3+-doped CaF2 ceramic. (Image by SIOM).

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Mr. Wu Xiufeng
General Administrative Office
Shanghai Institute of Optics and Fine Mechanics, CAS
Email: xfwu@siom.ac.cn