Airstream Gate 5 Fiber Optic Practice Test 2026 - Free Fiber Optic Practice Questions and Study Guide

Rayleigh backscatter comes from tiny, random density fluctuations in the glass that cause local refractive-index variations. These fluctuations exist all along the fiber, so light scatters in many directions as it travels, and a portion of that scattered light returns toward the source. Because the scattering centers are distributed throughout the material along the entire length, the backscatter is distributed along the fiber rather than being confined to a boundary. OH− impurities cause absorption at specific wavelengths rather than the volume, random scattering responsible for Rayleigh. And Rayleigh scattering is not restricted to a single wavelength; it occurs across the optical window (with strength that varies with wavelength), not only at 1550 nm.