Add/Drop Mode-Division Multiplexer Based on a Mach–Zehnder Interferometer and Periodic Waveguides

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 μm). 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.