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What is Microbending?
Microbending refers to small-scale, localized deformations along an optical fiber that can cause light to couple out of the guided mode and increase optical attenuation. Unlike macrobending, which results from a visible bend over a relatively large radius, microbending occurs on a much smaller scale and can be caused by mechanical pressure, manufacturing imperfections, or environmental changes.
Microbending is particularly important when designing fiber coatings, cables, and assemblies where mechanical stress can affect optical performance.
HOW Microbending Works
Microbending works through small, localized deformations of the fiber that disturb the propagation of the guided optical mode. These deformations can cause light to couple out of the guided mode, resulting in additional optical attenuation.
The principle can be understood through three main steps:
Local deformation
Small, irregular bends or pressure points modify the geometry of the fiber over very short distances.
Mode coupling
These small changes can cause energy to transfer from the guided mode into radiation modes or other modes within the fiber.
Increased attenuation
Part of the optical power is therefore lost, increasing the fiber's attenuation. The effect depends on factors such as the fiber design, wavelength, coating, and mechanical conditions.
