The longer the transmission distance of the optical module

The longest transmission distance for current optical modules can reach up to 1000 km using coherent 400G modules with FEC technology.

Overview of Transmission Distances

Optical modules vary widely in their maximum transmission distances depending on data rate, fiber type, and technology:

• Coherent 400G Modules: High-performance modules like the HTF 400G Muxponder can achieve up to 1000 km of regeneration-free transmission using coherent DWDM technology and Forward Error Correction (FEC), making them suitable for ultra-long-haul networks and high-capacity metro or intercontinental links .
• 25G SFP28 ZR Modules: These modules support up to 80 km over single-mode fiber (G.652), using EML lasers and WDM technology for bi-directional transmission .
• 10G SFP+ ER Modules: Designed for extended reach, these modules can transmit up to 40 km over single-mode fiber at 1550 nm, offering reliable performance for metro and campus networks .
• 1G and 10G LR Modules: Standard long-reach modules like 1000BASE-LR can transmit up to 10 km over single-mode fiber at 1310 nm, while 10G LR modules typically cover similar distances .

Factors Affecting Transmission Distance

1. Fiber Type: Single-mode fiber (SMF) supports longer distances than multimode fiber (MMF) due to lower attenuation.
2. Wavelength: Longer wavelengths (e.g., 1550 nm) reduce fiber loss and allow extended reach.
3. Coherent Technology: Coherent detection and advanced modulation formats significantly increase distance by improving signal integrity and dispersion tolerance.
4. FEC (Forward Error Correction): FEC allows error correction over long distances, enabling regeneration-free transmission.
5. Optical Power Budget and Receiver Sensitivity: Higher transmitter power and sensitive receivers extend the effective reach of the module.

Summary

While short-reach modules (SR, LR) cover meters to tens of kilometers, the longest practical transmission distance is achieved by coherent 400G modules, reaching up to 1000 km without repeaters. Modules like 25G ZR and 10G ER provide intermediate long-distance solutions for metro and enterprise networks, while standard 1G/10G LR modules are suitable for shorter long-reach applications. The choice of module depends on the required data rate, network topology, and cost considerations .