ABSTRACT
Almost all optical telecommunication systems throughout the world still operate in the 1.3-µm band. This is because a large amount of standard 1.3-µm single-mode fiber has already been installed. Therefore, there is great demand for the development of practical optical amplifiers for use at this wavelength. There have been three main approaches to meet this need: the neodymium (Nd3+)-doped fiber amplifier (NDFA), the praseodymium (Pr3+)-doped fiber amplifier (PDFA), and the Raman fiber amplifier. This chapter focuses mainly on the NDFA and PDFA.
