Light in optical fiber travels in the near-infrared region, far beyond visible light, and choosing the right transmission wavelengths is fundamental for minimizing loss and maximizing bandwidth. 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. Understanding these principles ensures your custom assemblies perform reliably across modern communication networks.