Large-Scale and Simple-Configuration Optical Switch Enabled by Asymmetric-Port-Count Subswitches

We propose a novel optical switch architecture for intra-datacenter interconnection. The proposed switch consists of asymmetric-port-count delivery-and-coupling (DC) switches and wavelength-routing (WR) switches based on arrayed-waveguide gratings (AWGs). To compensate for the insertion loss of the DC switch part and to suppress the passband-frequency deviation inherent in multiple-input-port AWGs, we employ a combination of an aggregation coupler, an erbium-doped fiber amplifier, and a single-input-port AWG for the WR-switch part. Moreover, we can reduce complicated fiber connections between the DC switches and the WR switches by making their port counts asymmetric. To confirm feasibility of the proposed switch architecture, we fabricate a 24 $\times$ 4 DC switch and a 16 $\times$ 8 DC switch with planar-lightwave-circuit technologies and evaluate the overall switching system. We construct part of 768 $\times$ 768 optical switch and part of 1536 $\times$ 1536 optical switch with the fabricated DC switches. Their excellent transmission characteristics are experimentally confirmed.