SEMICONDUCTOR OPTICAL AMPLIFIERS

The traditional way of compensating for optical loss in lightwave communication systems has been the rather cumbersome procedure of regeneration. Regeneration includes photon-electron conversion, electrical amplification, retiming, pulse shaping and finally electron-photon conversion. In many applications, direct optical amplification of the light signal would be advantageous. Optical amplifiers can be used in most systems that are loss limited; i.e, dispersion effects are not a limiting factor. This is the case for systems operating near the dispersion minimum at 1.3-mu-m, and for most coherent, externally modulated and solition systems at 1.5-mu-m. Local Area Networks, where the main losses are from branching and taps, are also loss limited and can benefit from simple optical amplifiers. This paper reviews some of the recent advances in semiconductor laser amplifiers and highlights some of the device and system issues connected with the use of optical amplifiers.