Innovative Characterization Methods for Next Generation Optical Fibers.

The increasing demand for higher data transmission rates and more efficient systems has driven the field of optical communications to explore new technologies beyond traditional single-mode fibers. As single-mode fiber systems near their theoretical capacity limits, a phenomenon referred to as the "capacity crunch," the need for novel solutions becomes critical. Space-division multiplexing has emerged as a promising technology capable of exponentially increasing the capacity of optical communication networks without requiring additional fiber deployment. This thesis investigates the characterization and optimization of space-division multiplexing fibers, focusing on overcoming the key challenges posed by modal dispersion, differential group delay, and mode-dependent loss. To address these challenges, advanced measurement techniques, such as optical vector network analyzer and Rayleigh scattering, have been employed to provide high-precision measurements of space-division multiplexing fiber transmission parameters. Additionally, a novel reflective optical vector network analyzer configuration has been explored, enabling reflective characterization of signal impairments over long distances. These characterization methods have been experimentally validated, including experiments on field-deployed space-division multiplexing fibers, demonstrating their applicability and robustness. Furthermore, the thesis delves into the study of environmental and shape sensing capabilities of these fibers, focusing on uncoupled multi-core fibers, paving the way for new innovative fiber sensors and for the future development of integrated networks where sensing and data transmission can coexist seamlessly. Through experimental validation and theoretical analysis, this thesis demonstrates the potential of space-division multiplexing systems to significantly enhance the capacity and efficiency of optical networks. The findings provide valuable insights into the future development of high-capacity, energy-efficient optical communication systems, contributing to the ongoing efforts to meet the ever-growing global demand for bandwidth.