Performance Under Tight Bends
It’s not unusual these days for optical fiber to be installed under bends as low as 15 mm in diameter. But even under these demanding conditions, signal quality cannot be sacrificed. Therefore, manufacturers are continuously innovating new methods to improve fiber bend performance.
LaserWave® FLEX 50 μm multimode fiber from OFS provides improved bending performance at tight radii by confining “higher order” modes (those operating closer to the core/clad interface) that normally escape from standard multimode fiber under bent conditions. To do this, OFS has modified the fiber cladding area surrounding the core to include a trench that prevents light from escaping. The trench area is carefully designed to properly confine and control this light in order to maintain excellent system performance and low connection loss, even when mated to standard 50 μm multimode fiber.
Because of this trench, careful inspection of the fiber’s end face (usually conducted with a fiber scope after connectorization) will reveal a difference from standard multimode fiber – a ring, or “halo,” around the core of the fiber. This “halo effect” is generated by the light source used for end-face inspection. These light sources fill the entire fiber end face, allowing careful inspection of not just the core, but also the cladding area. This is important when inspecting the quality of a connector finish, but it is not an indication of actual core size. OFS uses a standards-compliant core diameter measurement, combined with extensive interoperability measurements, to ensure that the halo has no negative effect on system performance.
OFS uses both the EMBc method and the more discriminating DMD Mask method to characterize bandwidth. The DMD Mask method verifies fiber performance more effectively, especially for higher order modes. Because of this, users of LaserWave FLEX fiber are assured that they will receive the same high-quality, high-bandwidth fiber they expect from standard LaserWave fiber, with the added benefit of superior bend performance.
Written by,
Stephen L. Cardone