Three-Dimensional Grain Boundary Spectroscopy in Transparent High Power Ceramic Laser Materials

TL;DR

This study employs 3D confocal Raman and fluorescence imaging to reveal Nd3+-Nd3+ interactions and segregation at grain boundaries in Nd3+:YAG ceramics, impacting laser performance and revealing inhomogeneities at high doping levels.

Contribution

It introduces 3D spectroscopic imaging to directly observe grain boundary interactions and segregation effects in transparent ceramic laser materials.

Findings

Nd3+ segregation occurs at grain boundaries causing fluorescence quenching.

Increased inhomogeneity in Nd3+ distribution at doping levels above 3 at%.

Standard spectrometry techniques do not detect these inhomogeneities.

Abstract

Using confocal Raman and fluorescence spectroscopic imaging in 3-dimensions, we show direct evidence for Nd3+-Nd3+ interactions across grain boundaries (GBs) in Nd3+:YAG laser ceramics. It is clearly shown that Nd3+ segregation takes place at GBs leading to self-fluorescence quenching which affects a volume fraction as high as 20%. In addition, we show a clear trend of increasing spatial inhomogeneities in Nd3+ concentration when the doping levels exceeds 3 at%, which is not detected by standard spectrometry techniques. These results could point the way to further improvements in what is already an impressive class of ceramic laser materials.