Semiconductor Optical Amplifiers.

Recent advances have brought semiconductor amplifiers to the stage where lightwave system employing amplifiers in some aspects clearly out-performs traditional systems. For example, the longest non-regenerated fiber transmission experiments use optical repeaters, and at high data-rates (4 GBit/s), receivers with optical pre-amplifiers are substantially more sensitive than their coherent and APD counterparts. In this paper we discuss the characteristics of semiconductor amplifiers with extremely low facet reflectivities. System experiments over 372 km of fiber using 4 optical amplifiers and a 4 GBit/s receiver employing an optical pre-amplifier will also be described.