A curve of millimeters to centimeters in radius, such as a fiber kinked in a tray, a cable pulled around a sharp corner or a jumper caught in a cabinet door. When the bend is tighter than the fiber can handle, light leaks into the cladding and is lost. Bend loss rises sharply at longer wavelengths, so an event far worse at 1550 or 1625 nm than at 1310 nm is the signature of a bend.
Loss at that event is 0.1 at 1310 and 1.2 at 1550, that's a macrobend, check the slack in the pedestal.
Also heard as
- macrobending
Do not mix it up with
- Microbend: A microbend is a microscopic deformation from pressure, not a visible curve in the fiber.
Related terms
Microbend
A tiny, invisible deformation of the fiber axis caused by pressure, which scatters light out of the core.
Bend radius
The tightest curve a fiber or cable can take without extra loss or damage, stated separately for pulling and at rest.
Bend-insensitive fiber
Fiber designed to lose very little light when bent tightly, used in drops, apartment wiring and dense patching.
Window
A wavelength region where fiber loss is low enough to run links, such as 850, 1310 or 1550 nm.
VFL
Visual Fault Locator: a bright red laser pen that shows breaks, bends and bad connectors as visible glowing points.