Design and Performance of 1×8 Core Selective Switch Supporting 15 Cores Per Port Using Bundle of Three 5-Core Fibers

A core-selective switch (CSS) is a key building block for a port modular spatial cross-connect where an optical signal launched into any core in the input multi-core fiber (MCF) can be switched to a core that has the same core identifier of any output MCF. One way to increase the core count in a CSS is to use several MCFs as a bundle and collimate/demultiplex beams emitted from it all at once using a single microlens. In this paper, we report a 1×8 CSS prototype based on a bundle of three 5-core fibers (5-CFs), which supports 15 cores per port, demonstrating the feasibility of a high core count CSS through MCF bundling. The CSS prototype exhibits insertion loss of less than 4.8 dB, and polarization dependent loss of less than 0.5 dB over an ultrawide wavelength range of 1480 nm to 1630 nm. The inter-core crosstalk (XT) characteristics as a function of the wavelength are thoroughly investigated. We show that the intra 5-CF XT imparted to the center core from the other four outer cores in the same 5-CF is less than −52 dB and the inter 5-CF XT from cores in the other 5-CFs in the same bundle is less than -64 dB, which are sufficiently low values for practical networks. No OSNR penalty in the 100-Gb/s spatial channel was observed when ten 100-Gb/s DP-QPSK WDM signals in the C-band were simultaneously routed by the bundled 5-CF 1×8 CSS prototype.