A system for transmitting an optical signal between a host and a device according to a SATA protocol. The system comprises a transmitting-side converter for generating a logic one voltage value responsive to a data one value from an information source, for generating a logic zero voltage value responsive to a data zero value from the information source, for generating an idle state logic voltage value, wherein the idle state logic voltage value is (logic one voltage value+logic zero voltage value)/2, the transmitting-side converter comprising only linear functions to preserve the idle state logic voltage value, and an electrical-to-optical converter for converting the logic one, logic zero and the idle state logic voltage values to an optical signal further comprising respective logic one, logic zero and idle state optical values and for supplying the optical signal to an optical communications medium.