What two wavelengths do multimode fibers most commonly use?

What two wavelengths do multimode fibers most commonly use?

• A. 850, 1300
• B. 1310, 1550
• C. 850, 1550
• D. 780, 1064

Answer: (A)

Multimode fiber uses light that comes from inexpensive, widely available sources and travels with manageable attenuation and dispersion in the fiber. The two wavelengths you’ll see most often are around 850 nm and 1300 nm. The 850 nm region is popular because inexpensive LEDs and VCSELs perform well there, and the fiber’s large core and high numerical aperture make coupling efficient for short-range, high-bandwidth links. The 1300 nm region is favored because silica fiber has relatively low loss in that window and devices for this wavelength were readily available, making longer links practical with multimode technology. Other wavelengths listed don’t align as well with common multimode sources or exhibit higher attenuation or dispersion for typical MMF applications, so they’re not the standard pairing.

Multimode fiber uses light that comes from inexpensive, widely available sources and travels with manageable attenuation and dispersion in the fiber. The two wavelengths you’ll see most often are around 850 nm and 1300 nm. The 850 nm region is popular because inexpensive LEDs and VCSELs perform well there, and the fiber’s large core and high numerical aperture make coupling efficient for short-range, high-bandwidth links. The 1300 nm region is favored because silica fiber has relatively low loss in that window and devices for this wavelength were readily available, making longer links practical with multimode technology. Other wavelengths listed don’t align as well with common multimode sources or exhibit higher attenuation or dispersion for typical MMF applications, so they’re not the standard pairing.