Fabrication and characterization of polycrystalline Ho:CaF2 transparent ceramics for 2.0 μm laser application

In this paper, high optical quality of Ho:CaF 2 (2   at%) transparent ceramics based on nanopowders were fabricated by hot-pressed method successfully. Ho:CaF 2 ceramics with the average size of about 500   nm were obtained at 800   °C for 1   h. The transmittance of the sample measured to be 89% at the wavelength of 1300   nm. The reduced transmittance in the near-IR range is likely due to the residual pores in the ceramics. The spectral properties of Ho:CaF 2 ceramics demonstrated that there is a strong emission peak around 2030   nm under the excitation of 640   nm.