What wavelength is often used for multi-mode fiber testing?

The answer, which involves both 850 nm and 1300 nm wavelengths, is correct because these wavelengths are standard for testing multi-mode fiber optics. Multi-mode fibers are designed to carry multiple light modes simultaneously and are primarily used for short-distance telecommunications and data communications due to their larger core diameter.

The 850 nm wavelength is commonly used in multimode fiber applications because it closely matches the peak output of the typical light sources used in these systems, such as LEDs and vertical-cavity surface-emitting lasers (VCSELs). This wavelength is particularly favored in short-range applications, such as within buildings or between buildings in a campus environment, where the distance does not exceed a few hundred meters.

The 1300 nm wavelength is also significant for multi-mode fiber testing, as it allows for longer distances compared to 850 nm due to lower attenuation and dispersion characteristics. This makes it suitable for applications that may extend further while still utilizing multi-mode fiber.

By incorporating both of these wavelengths in testing, technicians can ascertain performance and compatibility of multi-mode fiber installations for a variety of applications and ensure optimal system performance.