White Paper: Causes of Return Loss at Mated Single Mode Fiber Optic Connections


Return loss in fiber optic connections can significantly degrade system performance. Connections will exhibit return loss even if they are perfectly clean and possess ideal geometries. This paper explains how the complexities of different physical connections contribute to return loss, such as:

  • Contributions from small refractive index differences between fibers
  • Damage caused by endface polishing
  • Fiber deformation due to the connector spring force

This paper also explains how an angle polished on the fiber and connector helps to significantly reduce the return loss by directing reflected light at the endface of the connector out of the fiber core, hence reducing the light traveling back towards the source.
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White Paper: The Importance of Verifying a Reference Reflection for Accurate RL Measurements


Despite improvements in network technologies, return loss in networks and data centers continues to be an issue that results in decreased performance. As a result, it is important that it be measured accurately and properly account for any loss between the meter and the connection under test. This white paper discusses the following:

  • The benefits of limiting reflectance in a network
  • The effects of loss on return loss accuracy
  • A solution to identifying lossy cable setups
  • The importance of wide dynamic range for return loss measurements

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White Paper: Maximizing Return Loss Measurement Accuracy in Test Setups

White Paper Overview

With the wide range of fiber optic cables available for deployment (hybrid, multifiber, etc.), the test setups needed to evaluate them have become quite complex. The complexity required to test these cables often introduces additional insertion loss, resulting in uncertainty and erroneous return loss measurements. To ensure measurement accuracy, it is advisable to find a correction factor for each channel of each reference cable to zero out this variance. An established method to do this is to use an external reflectance standard. Awareness of this phenomenon will help manufacturing engineers and technicians accommodate and correct for potential sources of error.

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