Very low-loss GeO/sub 2/-doped silica waveguides fabricated by flame hydrolysis deposition method

GeO/sub 2/-doped silica single-mode waveguides are fabricated by flame hydrolysis deposition and reactive ion-etching methods, and the loss value measured using a 40 cm long waveguide circuit. The fabricated single-mode waveguides with fourteen 90 degrees bends with a small bending radius of 5 mm have a very low loss value of 0.04 dB/cm, leading to an estimated propagation loss in the straight waveguides part of (0.01 +or- 0.01) dB/cm.