The downstream wavelength is typically 1490 nm or 1577 nm, and the upstream wavelength is usually 1310 nm or 1270 nm. Supports point-to-multipoint (P2MP) multicast. PON networks enable simultaneous access for multiple users over a single optical fiber, supporting point-to-multipoint (P2MP) transmission. Data transmission from the OLT to the ONU is defined as downstream, while transmission from the ONU to the OLT is upstream; full-duplex transmission is adopted. Former is suitable for long link distance to Mars and the latter is suitable for high data rate at 60 Mb/s. The proposed technology can also be applied to Er doped fiber to produce near 1. Fortunately, we are also able to make. 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. are found in the RP Photonics Buyer's Guide.