Multimode Fiber Certification: Light Source Launching Conditions and Encircled Flux Standard

A multimode light source with controlled launch conditions ensures accuracy, reproducibility and consistent loss readings. The type of light source used for multimode fiber-link certification and the way it is coupled to the fiber greatly affects the launch conditions.

Generally, surface-emitting LED sources overfill the fiber, while edge-emitting light sources (EELS), including LED and laser sources, have a smaller spot size, numerical aperture and emission, which means they significantly underfill the fiber. Vertical-cavity surface-emitting lasers (VCSELs) are similar to laser light sources and also underfill the fiber.

Read on to learn more about the impact of the new Encircled Flux standard on launch conditions and measurements.