Optical losses influence fiber optic performance. It is important to understand how different components of a system including the optical fiber, splices, connectors, light sources, and receivers work together to identify the reason behind optical loss and help us develop solutions that allow fiber technology to reach its true potential.
Why Test Optical Loss
The objective of optical loss testing is to improve performance. Applications that work on higher data rely on Multimode fiber and usually have strict requirements of the maximum acceptable loss between the transmitter and the receiver. Systems with higher data rates tend to have tighter budgets for losses.
Next, we will examine the factors that affect optical loss testing accuracy:
Factors That Influence Optical Loss Testing Accuracy
Various factors can affect the accuracy of the optical loss testing, these include:
Test Reference Cords
The test reference cord’s quality and type can have a major impact on the accuracy of optical loss measurements and testing. It is imperative that the end-face geometry of the polished ferrule of the cord connector meets precise parameters such as radius of curvature, apex and fiber protrusion.
Incongruity In The Fibers Of The Test Reference Cords And The Link
Fiber mismatches can be the result of the actual fiber and do not hinge on the fiber optic splicing techniques used to join the fibers of two multi-mode cords. The coupling loss due to mismatched fiber can also be caused by the differences in the diameter of the fiber’s core diameter differences, issues with the cladding concentricity and the differences in the numerical aperture.
Light Source Coupling Issues
The light source, launch conditions and the way the light is coupled into the fiber have a substantial impact on the measurement and testing of optical loss. In multimode fiber, the different distributions of light at different angles can result in different measurements.
Tools For Testing Optical Loss
Currently, there are multiple types of testing equipment on the market, including the widely used fiber visual fault locator (VFL), power meters, cable tester and optical time-domain reflectometer (OTDR).
Optical Loss Test Set (OLTS)
The purpose of the Optical loss test set (OLTS) is to match the specifications of the installed system with the right connector adapters. For system testing, professionals also use a power meter and source to test the transmitter and receiver power.
Reference Test Cable
A reference test cable is used to ensure that a proper sized fiber is used with connectors to ensure mating adapters compatibility.
Visual Fiber Tracer
Visual fiber tracer (VFL) or visual fault locator (VFL) is also an important tool for testing optical loss by identifying fibers.
A microscope is used to inspect connectors usually using magnification of 100-200X. Experts suggest using video microscopes recommended.
Various specialized cleaning materials are also used for cleaning of fiber optic connectors. These include pure alcohol, cleaning kits or cleaning wipes.