Compact 8×8 SOA-Based Optical WDM Space Switch in Generic InP Technology

As the global internet protocol (IP) traffic volume growth puts more pressure on network connectivity, bandwidth and latency requirements, crucial network elements such as switches need continuous improvement. To this end, we report a monolithically integrated, ultra-compact 8×8 optical space switch based on semiconductor optical amplifier (SOA) gates, utilizing ultra-compact bends and denser SOA placement and demonstrating a strictly non-blocking broadcast and select (B&S) switch architecture on-chip. The switch circuitry comprises 80 SOAs, 112 multimode interference (MMI) splitters, and hundreds of waveguide bends and crossings integrated onto a 4.6×8 mm
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generic indium phosphide (InP) die with I/O access on the same side. In addition, the SOA waveguide geometry is specifically optimized to improve output saturation power by 2 dB and enable WDM operation. The physical layer characterization shows lossless operation on-chip due to the three SOAs in a path that provides enough gain to compensate for on-chip passive losses. The best-case OSNR is higher than 40 dB. We perform static data signal routing with four-channel wavelength division multiplexed (WDM) data signals at 25 Gb/s and 35 Gb/s, resulting in a worst-case 2 dB power penalty on receiver sensitivity. Additionally, we dynamically switch data signals at bit rates up to 35 Gb/s obtaining a power penalty similar to the static routing. The recorded rising and falling times are 4 and 6.4 ns, respectively, suggesting this chip is suitable for packet-scale fast switching applications.