Coherence multiplexing (CM) is a specific form of CDMA that is particularly suitable for optical communication systems for medium data rates and small distances. By virtue of its potentially simple implementation, it is particularly useful for "bridging the last mile" to the subscribers, which is an issue that is receiving considerable attention in optical communication research nowadays. The receivers in coherence multiplex systems published so far were all based on either self-homodyne or self-heterodyne detection. Both solutions are rather complicated, and therefore, expensive. In this paper, a new CM receiver concept is proposed, based on optical phase diversity detection. Theoretical performance results are derived for several modulation formats and receiver structures.