Current Directions in GaAs Laser Device Development

Lightwave communications systems, which send information by encoding it onto light beams propagating in hair-thin glass fibers, are now undergoing rapid development throughout the world. These systems, which, it may be no exaggeration to say, will revolutionize terrestrial communications techniques, have been made possible mainly by two technological achievements. The first is the development of glass optical fibers with small optical attenuations (less than about 50 percent per kilometer). The second is the development of semiconductor light sources for efficiently producing the light which ip transmitted in these fibers. The purpose of this paper is to describe several of the recent trends and problems in the development of (Al,Ga)As injection lasers which, together with light-emitting diodes made from the same materials, are the principal light sources of this lightwave revolution. A comprehensive treatment of the subject of injection lasers is not intended. The size of the field and the rapid pace of its progress make this difficult. 669