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Core-less End Caps

Definition: end pieces attached to fibers, containing no fiber core

Categories: fiber optics and waveguides, lasers

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For some fiber optics applications, particularly in the area of fiber amplifiers and lasers, it can be helpful to use optical fibers with core-less end caps. These end caps are essentially homogeneous transparent pieces with a length of a few millimeters, for example. As the end caps contain no waveguide (fiber core), light propagates in these regions as beams which expand toward the ends.

core-less end cap
Figure 1: A fiber with core-less end cap. A beam from air is adjusted such that its focus is where the waveguide structure in the fiber begins.

Such end caps can be made by attaching (e.g. fusion splicing) small pieces of homogeneous glass to the fiber ends. In case of photonic crystal fibers, it can be sufficient to heat the fiber end e.g. with a fusion splicer, so that the microscopic holes collapse.

The possible advantages of core-less end caps are:


[1]Y. O Aydin et al., “Endcapping of high-power 3 μm fiber lasers”, Opt. Express 27 (15), 20659 (2019), doi:10.1364/OE.27.020659

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See also: fibers, fiber lasers, fiber amplifiers, photonic crystal fibers, fiber optics
and other articles in the categories fiber optics and waveguides, lasers


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