System structures are described that use a centralized optical source for supplying all optical power needs-signal generation and coherent detection. In the configurations described the following benefits occur. Functional systems can be implemented with already demonstrated, and in many cases readily available components. There is no need for local oscillator optical sources and there is no need to stabilize the local oscillators with respect to a remote transmitter frequency to achieve coherent detection. Increases selectivity against other signal frequencies and increased signal-to-noise result from the use of coherent detection. When configured to equalize reference and signal time delay paths, both slow and fast laser source phase and frequency jitter are compensated for. One may therefore efficiently implemented multiple-access frequency division multiplexed networks in which the individual communication bandwidths are small compared to the linewidth of the laser power source. >