The light reflected back towards the source from the fiber ends and fiber deformations.

In cases where light is launched into an optical fiber, backreflection refers to the light that is returned to the launch point.

(BR): A term applied to any process in the cable plant that causes light to change directions in a fiber and return to the source. Occurs most often at connector interfaces where a glass-air interface causes a reflection. Backscattering: The return of a portion of scattered light to the input end of a fiber; the scattering of light in the direction opposite to its original propagation.