Fiber optic patch cords do not have “polarity” in the sense of electrical positive and negative terminals, like a battery. Plugging them in “backwards” will not cause a short circuit, and it will not burn out or damage your equipment. Because fiber duplex links rely on matched transmit-receive alignment, polarity determines how cables, connectors. discusses the impact of polarity as it pertains to serial duplex signals and parallel signals. Type B adapters shall mate two. Successful installation of a fiber-optic network employing multi-fiber push on (MPO) cables and connectors relies on several considerations, one of the most important of these is fiber polarity. A link's transmit signal (Tx) must match its corresponding receiver (Rx) at the other end.