Mode-division multiplexing (MDM) is currently under study due to its potential
to further increase data rates in optical communication circuits. In this paper, we propose
an add/drop MDM for the first- and second-order modes that cover the whole C-Band
(1.53–1.57 m). The device is based on a Mach–Zehnder interferometer, including periodic waveguides in the arms. Mode selectivity is provided by means of the periodic
waveguides, which are designed to allow the propagation of the second mode and to
reflect the first mode. The proposed device exhibits less than 1 dB insertion loss and
more than 30 dB extinction ratio in the whole C-Band. Furthermore, it presents wide
fabrication tolerances.
