ABSTRACT

Erbium-doped ber ampliers (EDFAs) are critical for the emergence of wavelength-divisionmultiplexing (WDM) systems in optical communications, which are largely responsible for the rapid bandwidth increase of the internet in the past two decades. The modern high speed internet has transformed societies across the globe in very fundamental ways. The huge potential bandwidth available in optical bers was realized very early on. The exploration of this available bandwidth using WDM started only after EDFAs enabled the simultaneous amplication of many WDM channels in the optical domain, therefore eliminating the costly high speed electronics in repeaters.