Abstract

Optical amplifiers are key components for optical communications for the various roles as preamplifiers, regenerators or post-amplifiers. Conventional co- and counter-propagating amplifier designs use three out of four ports of a multiplexer device (e.g. bulk or fiber): the pump port, the signal port and the common port leading to the amplification medium (e.g. rare earth doped fiber). Generally, the fourth port is blocked or used as a pump or signal tap. In amplifier designs with two or more pumps, each pump requires a separate multiplexer unit increasing optical loss, fabrication complexity and costs. Furthermore, cross talk between pumps can lead from minor amplifier gain and noise instability to catastrophic failure of the pumps¹. Insertion of additional isolators to protect the pumps from optical feed back or the use of hybrid pumping² of the amplifier configuration reduces this crosstalk problem.

© 1993 Optical Society of America