Multimode fiber is designed to operate at 850 and 1300 nm, while singlemode fiber is optimized for 1310 and 1550 nm. One of the major advantages of 1550 nm transmission is compatibility with Erbium-Doped Fiber Amplifiers (EDFA). All Singlemode fibers work very similarly in either wavelength—that is, you don't need to buy fiber based on wavelength, one fiber fits all. So, IF your cable assembly is built. This article delves into why 850, 1310, and 1550 nm are standard, what less-known regimes and tradeoffs exist, and how an OEM fiber-cable manufacturer can design and test with wavelength considerations built in. Consider the balance between attenuation and dispersion when designing your network for optimal performance.