What is Fiber Fuse : Basics & function

Fiber fuse is a destructive phenomenon in optical fibers where high optical power generates a plasma that propagates backward through the fiber, causing permanent damage. Fiber fuse can significantly impact high capacity optical communication systems, making proper power management essential for network reliability and protection. This page explains fiber fuse basics and its function within a fiber optic network.

A fuse is a safety device that interrupts the flow of current when an electrical circuit is overloaded. A fiber fuse performs a similar function to electric fuse, but specifically in optical fiber networks.

When an optical fiber network is subjected to very high optical intensity (typically greater than 2 MW/cm$^2$), the fiber cable can be shocked and damaged. This damage can cause the fiber to vaporize. The resulting defect becomes reflective, causing the signal to propagate back to the transmitter.

Figure: Fiber Fuse test set up

The figure above illustrates a typical setup used for fiber fuse testing.

In undersea fiber optic networks, high power levels are commonly used. In these applications, a fiber fuse serves as a crucial protection device. It’s placed at the transmit end and is designed to break the circuit, preventing further damage in the high-load scenarios mentioned above. This protects the sensitive and expensive equipment connected to the fiber.