Wavelength division multiplexing two channels on one fiber is one approach that enables us to make use of the extremely large bandwidth of optical fibers. We start with an analysis of optical fibers, sources, detectors, filters and wavelength division ,multiplexers. Then, using the knowledge from the experimental data, we design a 20 km bidirectional WDM datalink. The design is backed up with theory and measurements. Fiber to the home is one of many applications that makes use of such a design. / Master of Science