About 850 nm wavelength is used for the OSFP 400G DR4 transceiver module which is primarily designed to allow transmission through the multimode fiber (MMF) up to 100m. First, let's clarify what VR, SR, DR, FR, LR, ER, and ZR stand for, so that we can understand and identify them: VR (Very Short Range): Transmission distance usually 0~100 meters, using multimode fiber for short data center connections. This transceiver module features a 4-channel architecture, which allows sending 100 Gbps each to achieve an aggregated total of. NADDOD's 400G DR4/DR4+ & FR4 optical transceivers comply with the IEEE 802. 3cu (Draft) standards and employ a platform-based hardware design. They can meet the transmission requirements of 500m and 2km, respectively. DR4 uses parallel single-mode optics over MPO fiber, while FR4 and LR4 rely on CWDM wavelength multiplexing over. The 400G electrical signal is also split into four signals, but the difference is that in FR4, each signal drives a laser operating at a different central wavelength (such as 1271nm, 1291nm, 1311nm, 1331nm).
