For ordinary standard optical fiber, when the bending radius is small, the bending loss will be larger. However, in FTTH, due to the limitation of wiring location, zigzag wiring is often needed, which requires the fiber to have good bending resistance under small bending radius. Based on this, bend insensitive fiber emerges as the times require.
Bend insensitive fiber has two attractive characteristics: low intrinsic loss and excellent macro bend. Even if the bending radius is 7.5mm, the additional loss of 1625nm window is only 0.8db. Therefore, this kind of optical fiber can ensure the normal transmission of optical signal in the state of small bending radius or even knot, without huge loss. In many cases, the use of bend insensitive fibers does not even cause loss.
The core diameter and numerical aperture of bend insensitive fiber are different from those of traditional fiber, and the mode field distribution of them is also different. Therefore, the matching degree of the two fibers will be reduced, which may lead to the increase of connection loss. However, the test results show that the optimized bend insensitive fiber can be reversed to the traditional fiber without additional loss. Therefore, in the layout of bend insensitive fiber link, the whole link can use bend insensitive fiber, or a part of traditional fiber can be used together with bend insensitive fiber.
Bending insensitive optical fiber can be used in all kinds of fiber optic cable structures to improve space utilization and reduce the fiber loss of the whole network. It is suitable for FTTH, data center and other compact optical fiber management systems, especially the inner tight sleeve optical cable. It is the first choice for fiber to home and fiber to building.
