Heterogeneous space switches for power-efficient optical interconnection networks

Space switches are the fundamental elements in single plane and multi-plane optical interconnection networks. This paper proposes a heterogeneous implementation of optical space switches based on two gating elements, amplifiers such as semiconductor optical amplifier (SOA) and modulators such as Mach-Zehnder modulators. The heterogenous implementation has the advantage of being more power-efficient than a homogeneous implementation based only on SOAs and more scalable than a homogeneous implementation based only on modulator-based gates as the optical power loss can be compensated by the SOAs. The paper derives the requirements in number of gating elements for different space switch architectures (i.e., crossbar, Beneš, Spanke, Clos, Spanke-Benes, and hybrid Clos). Based on the such derivation, the scalability and the power-efficiency of the different non-blocking architectures with heterogeneous design are assessed, with the aim at identifying the most suitable architecture based on today´s available optical technologies. Results show that power saving around 80% are achievable when using a heterogeneous implementation instead of a homogenous SOA-based implementation.