Preparation and characterization of sol-gel derived YAG optical planar waveguide

YAG optical planar waveguide was elaborated through sol-gel method. Acetate-alkoxide (YAG-I) and 2-alkoxides (YAG-II) methods were used for the sol preparations. The as-deposited layers were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), m-lines spectroscopy (MLS) Rutherford Backscattering Spectroscopy (RBS) and waveguide Raman spectroscopy (WRS). No intermediate phases were observed for both synthesis routes. In comparison, (YAG-II) layers presented a better adherence than YAG-I to SiO₂ substrate, a higher refractive index and allowed to form a pure phase of YAG at lower temperature and short heat duration (900°C for 10min). However, the interdiffusion of Al and Si ions were detected to influence the refractive index improvement by heat treatments. The propagation loss of the fabricated YAG thin films in amorphous phase can be as low as 1.5±0.3 dB/cm.