Er(3+)-doped transparent glass ceramics containing micron-sized SrF(2) crystals for 2.7 μm emissions

Er(3+)-doped transparent glass ceramics containing micron-sized SrF(2) crystals were obtained by direct liquid-phase sintering of a mixture of SrF(2) powders and precursor glass powders at 820 °C for 15 min. The appearance and microstructural evolution of the SrF(2) crystals in the resulting glass ceramics were investigated using X-ray diffraction, field-emission scanning electron microscopy and transmission microscopy. The SrF(2) crystals are ~15 μm in size and are uniformly distributed throughout the fluorophosphate glass matrix. The glass ceramics achieve an average transmittance of 75% in the visible region and more than 85% in the near-IR region. The high transmittance of the glass ceramics results from matching the refractive index of the SrF(2) with that of the precursor glass. Energy dispersive spectroscopy, photoluminescence spectra, and photoluminescence lifetimes verified the incorporation of Er(3+) into the micron-sized SrF(2) crystals. Intense 2.7 μm emissions due to the (4)I(11/2) → (4)I(13/2) transition were observed upon excitation at 980 nm using a laser diode. The maximum value of the emission cross section of Er(3+) around 2.7 μm is more than 1.2 × 10(−20) cm(2), which indicates the potential of using transparent glass ceramics containing micron-sized SrF(2) crystals for efficient 2.7 μm lasers and amplifiers.