What Is Return Loss?_
Return loss measures the amount of light reflected back toward the source at a fiber connection, measured in decibels (dB). Higher return loss values are better (more light passes through, less reflects back). Poor return loss indicates dirty connectors, air gaps, or physical damage. It is tested alongside insertion loss during fiber certification.
Technical Details
Return loss (also called optical return loss, ORL) is caused by Fresnel reflections at glass-to-air interfaces (connectors, breaks) and by Rayleigh backscattering within the fiber. UPC (Ultra Physical Contact) connectors typically achieve >50 dB return loss, while APC (Angled Physical Contact) connectors achieve >65 dB by angling the ferrule end-face at 8° to reflect light out of the core. In GPU data centers using MPO connectors, return loss is particularly important because the multi-fiber interface has more potential reflection points. Poor return loss can cause signal degradation in high-speed transceivers, leading to increased bit error rates at 400G/800G speeds.
How Leviathan Systems Works with Return Loss
Leviathan Systems measures return loss as part of our fiber certification process, ensuring all connections meet TIA-568 requirements for the deployed link type.