Multichannel OADM using cascaded Bragg grating/Mach–Zehnder interferometers in SOI

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Why is it important?

There is growing interest in developing devices in silicon photonics that provide wavelength selectivity such as optical add drop multiplexers to support WDM transmission in optical interconnection applications (including data center communications) in addition to conventional fiber optic communications. Various OADM configurations based on ring resonators or grating-assisted contra-directional couplers have been reported. Bragg grating/Mach-Zehnder interferometer (BG/MZI) configurations are attractive as they provide the capability to shape the spectral response of the add-drop channel (by controlling the BG parameters) and because they can be cascaded to implement a multichannel device. To date, only single channel BG/MZI OADMs with limited performance (in terms of transmission isolation) have been reported. In this paper, we demonstrate a multichannel BG/MZI OADM that exhibits high transmission isolation. Moreover, we perform a detailed characterization of the OADM in terms of interferometric crosstalk. These OADMs should be useful for providing networking/routing functionality in optical interconnection applications.