A 1 Mbit/s optical data bus employing micro-optic directional couplers, which can compatibly replace an electrical bus cable in an in-line work station computer system connecting a central processor and four work stations up to 1.5 km apart, has been developed, and the feasibility has been confirmed.

Receiver sensitivity improvements as much as 16.4 dB and 4.1 dB over direct detection and ASK heterodyne detection, respectively, have been realized in 32 Mb/s PSK heterodyne detection simulation experiments using a 1.3µm wavelength laser diode.