Research issues in the next-generation photonic network physical layer

The explosive demand for bandwidth for data networking applications continues to drive photonics technology to ever-increasing capacity and flexibility at the optical physical layer. This is achieved with new optical components for routers, cross-connects, and add-drop multiplexers. We can expect continued capacity (per fibre) increases from the current Tb s(-1) level to some 100 Tb s(-1) before fundamental limits inhibit progress.