You use 1310nm and 1550nm fiber wavelengths because these points in the optical spectrum offer the lowest signal loss, which means you can transmit data efficiently. The table below shows how attenuation. 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. This guide provides a structured, engineering-level explanation of SFP wavelengths, including comparison tables, link-budget logic, deployment checklists, and common troubleshooting scenarios.