Which type of optical coupler is known to provide the least amount of insertion loss?

Fused couplers are known for their low insertion loss, making them a preferred choice in optical fiber applications. The design of fused couplers involves the fusion of two or more optical fibers together, allowing light to couple between them with minimal loss. This process results in efficient light transfer because the fibers maintain high uniformity and close tolerances, reducing scattering and reflections that can contribute to insertion loss.

Fused couplers also have the advantage of being able to be designed for specific splitting ratios and can operate over a broad range of wavelengths. This flexibility, combined with their low loss characteristics, makes them especially suitable for a wide variety of optical networking applications. Their performance benefits are significant when high efficiency is required, such as in telecommunications where signal integrity is crucial.

In contrast, other types of couplers might introduce more loss due to mechanical connections or less precise designs, thus making them less favorable in scenarios where minimum insertion loss is a priority.