Gigabit switch optical port wavelength

Gigabit Ethernet optical ports typically operate at 850 nm for short-reach multimode fiber (1000BASE-SX) and 1310 nm for long-reach single-mode fiber (1000BASE-LX).Short-Reach Multimode Fiber (1000BASE-SX)1000BASE-SX is designed for short-distance links over multimode fiber. It uses a wavelength range of 770–860 nm, with 850 nm being the most common. Maximum distances depend on fiber type and quality:62.5 µm fiber: 220–275 m50 µm fiber: 500–550 mLaser-optimized OM3/OM4 multimode fiber can extend reach up to 1 km . This standard is widely used for intra-building connections, data centers, and carrier-neutral exchanges.Long-Reach Single-Mode Fiber (1000BASE-LX)1000BASE-LX supports longer distances, typically up to 10 km over single-mode fiber. It operates at a wavelength of 1270–1355 nm, with 1310 nm being standard. When used with multimode fiber, the maximum distance is around 550 m, often requiring a conditioning patch cable for links over 300 m . The LX standard is ideal for building-to-building links, campus networks, and backbone extensions where copper or short-reach multimode optics are insufficient.Extended and Non-Standard Variants1000BASE-LSX: Industry-accepted term for extended-reach multimode fiber, achieving distances up to 2 km using higher-quality optics at 1310 nm .1000BASE-ZX: Operates at 1550 nm for very long distances (up to 70 km), though less common in standard Gigabit Ethernet deployments.Summary TableStandardFiber TypeWavelength (nm)Typical Max Distance1000BASE-SXMultimode850220 m–1 km1000BASE-LXSingle-mode131010 km1000BASE-LSXMultimode13102 km1000BASE-ZXSingle-mode155070 kmThese wavelengths are critical for selecting compatible SFP modules and ensuring proper link performance. Multimode fiber uses shorter wavelengths for short distances, while single-mode fiber uses longer wavelengths to minimize attenuation over long distances .