The issue could also be caused by a faulty fusion splice, misalignment or incorrect polarity. Fiber Optic Testing Testing is used to evaluate the performance of fiber optic components, cable plants and systems. Passive components consist of all the links and connections that unite communication devices on the overall network. System performance is typically evaluated on an individual link basis between any two given nodes of the. Fiber optic cables are essential for modern telecommunications and data networks due to their high bandwidth and long-distance transmission capabilities.