Modification of Er:YbAG film microstructure with a sintering agent

Thin films of erbium doped YbAG were prepared by spin-coating on fused silica substrates. The effect of two parameters on the microstructure of resulting films was observed: addition of a sintering agent (TEOS) to the solution deposited and crystallization under decreased atmosphere (100 mbar). All prepared samples were polycrystalline single phase YbAG. When comparing the reference (TEOS-free) samples crystallized in ambient pressure, the films with TEOS in a combination with decreased pressure during the crystallization had a smaller crystallite size and finer surface, as confirmed by AFM and Williamson–Hall analyses. A higher amount of TEOS caused cracking of the films though. All films containing TEOS were one-mode waveguides in the NIR region. This paper shows a way to modify microstructure of a waveguiding film via addition of a sintering agent without destroying the waveguiding ability. (paper)