Bi3+-Sensitized La2Zr2O7:Er3+ Transparent Ceramics with Efficient Up/Down-Conversion Luminescence Properties for Photonic Applications

Optical gain materials are of great importance for photonic applications, particularly in the realization of high-performance lasers and amplifiers. Unfortunately, the relatively poor thermodynamic stability greatly restricts their applications in harsh environments. Here, promising gain materials with harsh-environment endurance, transparent La2Zr2O7:Er3+,Bi3+ (LZO:Er,Bi) ceramics, were fabricated successfully. The LZO:1% Er,2% Bi ceramics exhibit the highest in-line transmittance of 64.8% at 1300 nm. Enhanced photoluminescence from Er3+-doped LZO sensitized with Bi3+ has been observed. We systematically study the sensitization mechanism of Bi–Er coupling from both up- and down-conversion. The former originates from the energy back-transfer and the modification of the symmetry of the crystal field in the lattice, where the modification of the crystal field is dominant during an up-conversion sensitized process. The latter is attributed to the efficient energy transfer (ET) from Bi3+ to Er3+. The calculated ET efficiency ηET is about 72%. The most probable ET mechanism from Bi3+ to Er3+ in LZO ceramics is the dipole–dipole interaction. The LZO:Er,Bi transparent ceramics with excellent thermal stability, effective luminescence, and a long metastable-level lifetime can be potential candidates as optical gain materials for photonic applications in severe environments.