Observation of Blowing Out in Low Loss Passive Optical Fuse Formed in Silica Glass Optical Fiber Circuit

Low loss (less than 1 dB) passive optical fuses were realized by inserting 50-um-thick TeO2 glass layer into a single-mode silica glass fiber circuit with carbon coating. On the basis of real-time observation of their fusing action, the mechanism of losing its transparency is discussed. The observed loss drop is found to be an overlap of decoupling of the circuit and transient light flux from the burned coating. The critical input power to blow out is expected to be raised by eliminating its insertion loss.