Synthesis and characterization of optical properties of soft and hard Er3+-doped (K Na)NbO3 piezophotonic ceramics

Abstract

Real-time tuning of photoluminescence properties are highly desirable for potential applications. Thus, one proposed approach is to tune the photoluminescence emissions by applying an external electric field. However, in order to switch the ferroelectric polarization, high quality bulk ceramics is demanded. In this work, soft and hard Er3+-doped (K,Na)NbO3 piezophotonic ceramics were prepared by the conventional route and their microstructural, structural and up-conversion emission properties were investigated. Dense and free from secondary phases ceramics were successfully produced. The photoluminescence spectra, in the visible range, were characterized as a function of the pumping power. For the soft composition, a remarkable green shift was verified with increasing the laser power. It was supposed that the excited state absorption, involving a three-photon absorption process, was involved in the 4S3/2→4I15/2 transition. For the hard composition, the two-photon absorption process was dominant and the presence of complex defects reduced significantly the 4F9/2→4I15/2 transition.