bendinsensitive

Bendinsensitive refers to an optical fiber design that minimizes macrobend losses when the fiber is curved or coiled at tight radii. The term is commonly used in telecommunications and data-center networks, where compact fiber routing makes tight bends more likely.

Most bendinsensitive fibers achieve this by altering the refractive-index profile near the core, typically by adding a trench or depressed-index region in the cladding surrounding the core. The trench lowers the effective index near the core boundaries, reducing the tendency of the guided mode to radiate into the cladding when the fiber is bent. This helps keep more optical power within the core at small bend radii, mitigating bend loss.

Variants include trench-assisted bendinsensitive fibers and depressed-cladding bend-insensitive designs. They are generally compatible with standard single-mode fiber splicing and connectorization and often maintain comparable straight-line attenuation to conventional fibers while offering significantly improved bend performance.

Applications include data centers, access networks, fiber to the home, and other links requiring compact routing and high tolerance to bending. Limitations may include higher manufacturing complexity, potential modest increases in baseline attenuation for certain designs, and cost considerations relative to standard fibers.

Manufacture typically involves processes such as modified chemical vapor deposition to create the trench or index-modification around the core during preform fabrication. There are multiple vendor implementations with varying trench dimensions and refractive-index contrasts.

See also: optical fiber, bend loss, trench-assisted fiber, depressed-cladding fiber.