Characterization of Ti : LiNbO3 waveguides by micro-raman and luminescence spectroscopy
Raman and luminescence spectroscopies are used for non destructive characterization of titanium-diffused LiNbO3 waveguides at the classical resolution of confocal microscopy (0.5×0.5×3 μm). The broadening of Raman lines near the surface permits one to measure the depths of lithium out-diffusion and titanium in-diffusion. The contrast of polaron luminescence makes it possible to control routinely the waveguides just after the diffusion process. Vertical scans give the thickness of the chemically-reduced layer near the surface of the wafer, whereas horizontal scans across the waveguides reveal screening effects by the titanium stripes against surface reduction.
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