Unified architecture of an integrated SDM-WSS employing a PLC-based spatial beam transformer array for various types of SDM fibers

There is no doubt that wavelength-division multiplexing will continuously play an important role in future space-division multiplexing (SDM) capable optical networks. In this paper, we propose a unified architecture for integrated wavelength selective switches (WSSs) that can be applied to various types of SDM fibers and recon-figurable optical add/drop multiplexer switching types. A recently reported planar lightwave circuit (PLC)-based spatial beam transformer (SBT) array is anticipated to be used as a key enabler for the architecture to integrate multiple WSSs on a single liquid crystal on silicon beam steering device. The architecture enables individual switching and power adjustment functionality of an SDM-WSS that supports an uncoupled single-mode multicore fiber (SM-MCF) in an economical manner. The same architecture provides fractional joint wavelength switching functionality in an SDM-WSS for a few-mode MCF (FM-MCF) and a grouped-coupled-core MCF (GCC-MCF) as well as joint wavelength switching in an SDM-WSS for multiple few-mode fibers with almost no additional hardware complexity. Preliminary scalability evaluation shows that a 1 χ 24 individual switching SDM-WSS for a single-mode eight-core uncoupled MCF or a 1 χ 7 fractional joint wavelength switching SDM-WSS for a three-mode eight-core FM-MCF or a three-coupled-core χ eight-group GCC-MCF is feasible using the SBT array design reported in the literature. The evaluation also shows that compared to the traditional approach based on conventional WSSs, the proposed architecture is anticipated to reduce the hardware footprint requirement by parallelism factor mC, where m and C indicate the number of modes per core and the number of cores per fiber, respectively.