A patch cord into which a collimator pair has been intercalated is attached to
the output end of a high-level light amplifier for transmitting high-level light
through optical fibers from outside in a replaceable manner. Even if burnout occurs
at an end face of an optical fiber and the heat is conducted to the patch cord
with collimators that is connected with an optical connector, meltdown by the fiber-fuse
phenomenon can be prevented before it reaches the high-power optical amplifier
without being propagated to the high-power optical amplifier because heat energy
is dissipated at the collimator pair. By this, the high-power optical amplifier
can be protected from the fiber-fuse phenomenon.
