Devices and methods for effecting and managing the bi-directional transmission of data and communications over a single optic fiber are provided. Methods and devices of the invention utilize fiber-optic transmitters and receivers made for WDM transmission, and at least two slightly different wavelengths, in the 1.5 um range. Devices and methods of the invention facilitate simultaneous bi-directional optical transmission over a long distance, while reducing or eliminating cross-talk.