Abstract

Optical amplifiers will be key components for increasing the versatility of optical fiber communications as in-line multichannel repeaters and preamplifiers.¹ Since the early investigation of Nd doped fiber amplifiers,^2,3 developments in vapor-phase techniques for fiber fabrication⁴ led to a renewed interest in a large variety of rare earth doped fiber devices.⁵ In particular, Er doped fibers, amplifiers, and lasers operating around 1.54 µm (Ref. 6) gained increasing attention as new devices for optical communications in the 1.5-Mm communication window.^7,8 Our purpose is to outline the state of the art of Er doped fiber amplifiers (EDFAs) and review the current device issues.

© 1990 Optical Society of America