The core selective switch (CSS) is an optical spatial switch that has been recently proposed as a key building block to achieve a scalable and low-insertion-loss spatial cross-connects for use in future spatial channel networks. In this paper, we report on a novel CSS design employing a two dimensionally arranged microlens-based multicore fiber (MCF) collimator array and a micro-electromechanical systems (MEMS) mirror array. The former enables precise alignment between MCFs and collimator lenses, and the latter yields polarization-independent high reflection over a wide wavelength range and a large tilt angle. Based on the design, a compact (~50 mm) five-core 𝟏 × 𝟖 CSS prototype is fabricated. We experimentally show that the CSS prototype exhibits low insertion loss (1.2~2.7 dB), low polarization dependent loss (< 0.25 dB), and low crosstalk (< −𝟑𝟎 dB) characteristics over an ultra-wide wavelength range from 1500 nm to 1630 nm. Bit-error-rate measurements using optical signals in the C-band, S-band, and L-band show that the CSS prototype incurs no optical signal-to-noise ratio penalty in spatial channel routing over an ultra-wide wavelength band.

We prototyped a 15-core 1×8 core selective switch (CSS). The high core count CSS is achieved by bundling three 5-core fibers (5-CFs) and collimating/demultiplexing beams from the input bundled three 5-CFs using a single microlens.

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.

A single multicore-fiber bidirectional spatial channel network that efficiently accommodates asymmetric traffic is proposed and demonstrated using a core-selective-switch-based spatial cross-connect with an M × N wavelength-selective switch and a bidirectional multicore EDFA with reversible optical isolators.