Fiber fuse generation in single-mode fiber-optic connectors

The evolution of the fiber fuse phenomenon in a single-mode fiber-optic connector was studied theoretically. A narrow air gap of the order of 1 μm was assumed to be formed between the fiber end-faces in the connector as a result of the adhesion of dust to both the ferrule and the fiber end-faces. It was assumed that there was a thin water layer in the gap because condensable water molecules in the air could easily be trapped by the SiOH groups on the silica-glass surface. The water layer exhibited a large absorption coefficient of about 850 cm/sup -1/ at 1.48 μm. The temperature distributions near the air gap were numerically calculated by using the explicit finite-difference method. When a high-power laser operating at 1.48 μm was input into the connector, the temperature along the fiber-core center increased abruptly at the thin water layer. The air gap was heated above 4×10⁵ K when the optical power was 2 W and the gap was 1 μm. The heat in the air gap gradually diffused into the neighboring optical fiber over time. The temperature of the heated fiber reached over 1×10⁴ K, which is high enough to initiate the fiber fuse phenomenon.