Fiber optic cables are designed to withstand some bending, but excessive bends can physically damage the glass fiber or cause significant signal loss. That's why every fiber cable has a minimum bend radius specification provided by the manufacturer. The minimum bend radius defines the smallest. General Symmetric cable pairs Land coaxial cable pairs Submarine cables Free space optical systems G. This can be explained by coupling of light from core modes. However, optical fibers are also fragile, and care must be taken to avoid bending or twisting them.