title: Monolithically integrated reconfigurable add-drop multiplexer for mode-division-multiplexing systems.
abstract: An integrated reconfigurable optical add-drop multiplexer (ROADM) for mode-division-multiplexing systems is proposed and demonstrated for the first time, to the best of our knowledge. The present ROADM with four mode-channels is composed of a four-channel mode demultiplexer, four identical 2×2 thermo-optic Mach-Zehnder switches (MZSs), and a four-channel mode multiplexer, which are integrated monolithically on silicon. All the devices are designed for operation with TM polarization. The ROADM can add/drop any one of the mode channels freely by thermally turning on/off the corresponding MZS. For the added/dropped mode-channels, the excess loss is 1-5 dB, and the extinction ratio is 15-20 dB in the wavelength range of 1535-1565 nm.
authors.forename: Shipeng
authors.initials: S
authors.lastname: Wang
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
authors.forename: Hon Ki
authors.initials: HK
authors.lastname: Tsang
authors.forename: Daoxin
authors.initials: D
authors.lastname: Dai