定义：从光纤一端射入强激光光束后使其另一侧的输出端烧熔的现象。

由于光纤中传播的模式面积很小，因此即使功率中等的情况下也能得到很高的光强。因此，如果在光纤入射端口进入一束激光光束后很容易破坏光纤，尤其是在光纤端口不洁净的情况下。但是，一种很奇怪的现象是光纤会在其出射端口开始熔化。这时可以看到一个白色的斑点，来自于光纤端口产生的大量等离子体。由于等离子体可以熔化光纤，它会沿返回到光纤入射端口的方向上，速度可以达到几米每秒。标准单模光纤中，如果光纤出射端有物质（例如，燃烧的粉尘颗粒）触发等离子体，当功率小于1W时就有可能发生这种现象。目前描述机制中还需注意的是，石英的吸收损耗在温度大于1000 °C时增长迅速。 

光纤熔化在通信系统中的影响是灾难性的，因为在某一点处的失误可能损坏很多千米的光纤。这是传输容量很大的光纤链路中需要考虑的问题。一种弥补的方案是在某些点处减小包层直径，这样光纤熔化在这些位置会停止。 

需要注意的是，高功率光纤放大器也面临很严重的光纤熔化问题，需要采取适当的测试来保证装置的可靠性。
 

Definition: the effect that an optical fiber “burns” from the output end under the influence of an intense laser beam launched into the other end

The small mode areas for light propagating through optical fibers lead to high optical intensities even for moderate power levels. It is therefore no surprise that particularly a fiber input end, into which a laser beam is launched, can easily be destroyed, particularly when the fiber end is not very clean. The more surprising effect, however, is that a fiber can also burn down starting from the output end. Here, a bright white spot can be seen, which results from a hot plasma forming at the fiber end. As this plasma fuses the fiber, it propagates back towards the input end with a velocity which can be several meters per second. In standard single-mode fibers, this phenomenon can occur already for powers below 1 W if something (e.g. a burning dust particle) triggers the plasma at the output end. An important ingredient for the underlying mechanism is that the absorption losses of silica sharply rise at temperatures above 1000 °C.

The effect of fiber fuse can be disastrous in a telecom system where kilometers of fiber may be destroyed as a result of a failure at only one point. This is a concern for fiber-optic links with extremely high transmission capacities. A partial remedy may be to reduce the cladding diameter at certain points so that the fiber fuse is stopped at such locations [2].

Note that high-power fiber amplifiers are at particularly high risk of suffering fiber fuse; appropriate measures have to be taken to ensure device reliability.

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