Integrated optical switch matrices for packet data networks

Integrated circuit technologies are enabling intelligent, chip-based, optical packet switch matrices. Rapid real-time re-configurability at the photonic layer using integrated circuit technologies is expected to enable cost-effective, energy-efficient, and transparent data communications. InP integrated photonic circuits offer high-performance amplifiers, switches, modulators, detectors, and de/multiplexers in the same wafer-scale processes. The complexity of these circuits has been transformed as the process technologies have matured, enabling component counts to increase to many hundreds per chip. Active–passive monolithic integration has enabled switching matrices with up to 480 components, connecting 16 inputs to 16 outputs. Integrated switching matrices route data streams of hundreds of gigabits per second. Multi-path and packet time-scale switching have been demonstrated in the laboratory to route between multiple fibre connections. Wavelength-granularity routing and monitoring is realised inside the chip. In this paper, we review the current status in InP integrated photonics for optical switch matrices, paying particular attention to the additional on-chip functions that become feasible with active component integration. We highlight the opportunities for introducing intelligence at the physical layer and explore the requirements and opportunities for cost-effective, scalable switching. Devices that can quickly redirect incoming packets of optically encoded data could substantially increase the speed of the Internet. Kevin Williams and colleagues have reviewed recent developments in large optical switch matrices with a particular focus on the work performed using Indium phosphide integrated photonics at the Eindhoven University of Technology in the Netherlands. Indium phosphide is a semiconducting material that can efficiently produce and amplify light. Optically active switches made from a single material can improve operation speed and reduce the optical and electrical energy consumption of the device. Thus, indium phosphide integrated photonic circuits can combine advanced routing and signal processing functions all on one chip. So far this technology has created switching matrices with up to 480 components, connecting sixteen inputs to sixteen outputs and routed data streams at rates of a few hundred Gigabits per second.