ABSTRACT
Optical fiber communication systems have continuously evolved over the years. The increasing demand for a higher transmission capacity has driven the development of communication systems at ultra-high capacities and ultra-high bit rates. The fact that a 40 Gbps optical fiber communication system can have an extended reach and improved capacity makes it an attractive alternative to the 10 Gbps optical fiber communication system. System performance is further enhanced by employing various advanced modulation formats, such as duobinary (DB), return-to-zero differential phase shift keying (RZ-DPSK), and non-return-to-zero differential phase shift keying (NRZ-DPSK) [1–10]. Research and investigations have been carried out to determine the most appropriate and efficient formats that meet the current as well as future demand.
