Layered OXC With Intermode Switching Bridge for Optical SDM-WDM Networks

Recently, spatial-division-multiplexing based on weakly coupled multicore or few-mode fibers has been proposed for short-reach switching scenarios, in which spatial mode can be used as an independent switching dimension. Fully connected cross-connections (OXC) converting all spatial modes and wavelengths into one-dimensional switching ports and followed by huge switching array can provide nonblocking switching, but the hardware implementation is very complex and expensive. In this paper, we propose a layered OXC structure consisting of intramode sub-OXCs and intermode switching bridges. Then, a scattered-spectrum-scan intramode-first routing and spectrum allocation (SSS-IMF-RSA) scheme is designed, in which only a few discrete spectrum segments instead of the whole spectrum should be scanned for spectrum allocation. The switching will be performed preferentially for the wavelength dimension because of mature switching capability and less searching time. We show by simulation that the proposed layered OXC with the SSS-IMF-RSA scheme can achieve similar blocking performance to fully connected OXCs with up to 76.1% hardware scale reduction and 93% searching time reduction for network accommodation. The proposed OXC and RSA scheme greatly decrease the requirements for the port number of WSS and enable components reuse to achieve smooth evolution.