WDM transceivers made for single-strand operation require the opposing transmitters to use different wavelengths. WDM transceivers additionally require an optical splitter/combiner to couple the transmitter and receiver paths onto the one fiber strand. Coarse WDM (CWDM) Transceiver Wavelengths: 1271 nm, 1291 nm, 1311 nm, 1331 nm, 1351 nm, 1371 nm, 1391 nm, 1411 nm, 1431 nm, 1451 nm, 1471 nm, 1491 nm, 1511 nm, 1531 nm, 1551 nm, 1571 nm, 1591 nm, 1611 nm.