Abstract: A multiplexer has an optical circulator including at least first, second and third circulator ports. An optical fiber with a first optical transmission path is coupled to the first circulator port of the optical circulator. The optical fiber carries a wavelength division multiplexed optical signal, including signals &lgr;1-&lgr;n, and at least one signal &lgr;1 to be dropped by the multiplexer. A second optical transmission path is in optical communication with the second circulator port. A first filter is coupled to the second optical transmission path. The first filter passes a portion of the &lgr;1 signal, and reflects a first residual &lgr;1 signal and signals &lgr;2-&lgr;n to the optical circulator. A third optical transmission path is in optical communication with the third circulator port and transmits the signals &lgr;2-&lgr;n received from the optical circulator.