Ring resonators composed of GeO/sub 2/-doped silica waveguides

Ring resonators composed of GeO/sub 2/-doped silica waveguides fabricated on silicon substrates by a flame hydrolysis deposition method are described. GeO/sub 2/-doped silica waveguides are developed to provide a lower propagation loss than that of TiO/sub 2/-doped silica waveguides. Since the finesse and transmission at resonance is determined mainly by total loss in the ring, the loss characteristics of the fundamental components are investigated in detail. Experimental and theoretical investigations show that a finesse of the ring resonator for GeO/sub 2/-doped silica waveguides is about 2.7 times higher than that for TiO/sub 2/-doped silica waveguides with the same transmission at resonance. >