Connector and Splice Losses: Every connector or splice in a fiber optic network introduces additional loss. This is a good page to bookmark on your smartphone, tablet and/or laptop to have for making calculations in the field. The detailed information about these optical losses and how to reduce them are. Loss (IL) and Reflection or Return Loss (RL). A superior connector will exhibit minimal optical loss, thanks to precise alignment of th s, cost-efectiveness, and ease of termination. Fiber optic testing of a newly installed system not only verifies that the system meets its design requirements, but also creates a performance baseline for all future testing and troubleshooting of t at system. Corning recommends that all fiber optic systems be tested to a minimum set. Insertion loss, also known as attenuation, is the loss of optical power that occurs when light passes through a fiber optic connector.