Bend-optimized multimode fiber’s halo effect explained

A technical report from OFS describes how and why its bend-optimized 50-micron fiber looks different from standard 50-micron fiber under a microscope.

Taken from a recent technical report issued by OFS, this image shows a standard OFS LaserWave 50-micron fiber endface (left) and a LaserWave Flex 50-micron fiber endface (right), which exhibits the 'halo effect' created by the trench that surrounds the fiber core.
Taken from a recent technical report issued by OFS, this image shows a standard OFS LaserWave 50-micron fiber endface (left) and a LaserWave Flex 50-micron fiber endface (right), which exhibits the 'halo effect' created by the trench that surrounds the fiber core.

A technical report recently issued by optical-fiber manufacturer OFS explains to fiber-optic installers and technicians why a microscopic inspection of a cable containing its LaserWave Flex 50-micron bend-optimized fiber will yield a slightly different look from an inspection of a cable containing the standard LaserWave 50-micron fiber. OFS explains in the report that it “has modified the fiber cladding area surrounding the core to include a trench that prevents light from escaping. The trench area is carefully designed to properly confine and control this light in order to maintain excellent system performance and low connection loss, even when mated to standard 50-micron multimode fiber.”

It’s the appearance of that trench that makes the fiber look different, OFS explains The images at the bottom of this screen are taken from OFS’s technical report; that report also reads, “This ‘halo effect’ is generated by the light source that is used for endface inspection. These light sources fill the entire fiber endface, allowing careful inspection of not just the core, but also the cladding area. This is important when inspecting the quality of a connector finish, but it is not an indication of actual core size.”

You can read and download the full technical report here.

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