Optical performance monitoring and signal processing to enable robust and reconfigurable optical networks.

摘要

For advanced optical networks at bit-rates beyond 100 Gbit/s, there is a desire to realize an evolution of the network architecture and cost-effective performance and scalability. Today's networks are typically built to operate within well-defined specifications and function in a fairly static fashion, and even a single failure can bring down the network services. As the data rates increase and the modulation formats become more complex, it becomes quite challenging to measure the data degradation mechanisms and to provide stable and accurate physical states to the network controller for data dropping, correction, compensation and routing. In order to enhance the functionality of network control and management, optical performance monitoring becomes an increasingly practical tool to overcome such challenges and to agilely reflect the physical state of the network and the quality of all data channels, enabling robust and reconfigurable networks. In this dissertation, we demonstrate OSNR, CD, and PMD monitoring methods particularly to accommodate various high-speed advanced modulation formats. These optical performance monitors presented here are easily deployable, compact, inexpensive, accurate, fast, stable and reliable.;High-capacity optical communication systems are currently developed to meet the inevitable growth in data capacity. Various methods that have been explored to maximize the information capacity of optical communication systems include higher-order modulation formats, polarization multiplexing and space-division multiplexing. Most recently, space-division multiplexing has been considered as an innovative tool to greatly increase the spectral efficiency by transmitting independent data streams via multiple spatial modes in a few-mode fiber, a multi-core fiber or a free-space link. In this dissertation, the main focus is placed on the demonstrations of free-space optical data links with high spectral efficiency and high capacity using spatially multiplexed orbital-angular-momentum (OAM) modes. In contrast to other spatial modes, the distinct features of OAM modes include excellent orthogonality in the spatial domain, low crosstalk among modes and high photon efficiency, making OAM modes useful in many optical signal processing applications.