Coherent optical communication systems became possible with development of the gas laser in the early 1960s. During the decade following development of the laser, Enloe and Rodda showed homodyne detection to be possible when they successfully phase-locked two gas lasers. DeLange and Dietrich showed that stable heterodyne detection was possible over an enclosed optical transmission path. However, not until the 1980s were optical waveguide and semiconductor laser technologies developed to the stage where they could be used for coherent optical fiber transmission.
© 1985 Optical Society of AmericaPDF Article