Structural characterizations and waveguiding properties of YAG thin films obtained by different sol-gel processes

Y3Al5O12 (YAG) thin films are prepared by the sol-gel process using two different synthesis routes: acetate-alkoxide method (YAG-I) and two-alkoxides method (YAG-II). The sols and films elaborations are described. The film behavior is studied by X-ray diffraction (XRD) and conventional transmission electron microscopy (CTEM) for different annealing temperatures. Differential thermal analysis (DTA) measurements are used for crystallization kinetics investigations. The refractive index and thickness of the as-prepared films are analyzed by m-lines spectroscopy (MLS) and their waveguiding properties are characterized. The relationships between structural evolutions and waveguiding properties of YAG thin films are discussed. These results show that the structural and optical performances of the elaborated YAG thin films strongly depend on the starting materials and their associated annealing treatments.