DEPARTMENT OF INFORMATION SCIENCE AND TECHNOLOGY Impact of In-Band Crosstalk on the Performance of Optical Coherent Detection Communication Systems Dissertation presented in partial fulfillment of the requirements for the Masters Degree on Telecommunications and Information Science by Bruno Rafael Pereira Pinheiro Supervisors: Dr. João Rebola, Assistant Professor, ISCTE-IUL Dr. Luís Cancela, Assistant Professor, ISCTE-IUL April, 2015