AN-135 Launch Conditions for Multimode Testing
Overview
An LED light source is required per IEC 61300-3-4 for testing insertion loss on multimode cabling/connectors. When LASER sources are used, outside influences, such as movement and settling in cable as well as changes in temperature, can cause output power instability which can affect insertion loss test results.
Controlling launch conditions is an important part of insertion loss testing. If the launch conditions are not defined or known for the reference lead and optical source, then the results will tend to be skewed depending on whether the launch overfills or underfills the fiber.