ABSTRACT
Optical fiber communication system has continuously evolved over the years. The increasing demand for a higher transmission capacity has driven the development of communication system at ultrahigh capacity ultrahigh bit rates. The fact that 40 Gb/s optical fiber communication system has an extended reach and improved capacity, it has become an attractive alternative to the 10 Gb/s 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 nonreturn-to-zero differential phase-shift keying (NRZ-DPSK). Research and investigations have been carried out to determine the most appropriate and efficient formats that meet the current, as well as future, demand.
