Digital phase conjugation for fiber-optic links

[0013]FIG. 1 shows a block diagram of a WDM communication system 100 according to one embodiment of the invention. System 100 is illustratively shown as having m>2 WDM channels. One skilled in the art will appreciate that, in alternative embodiments, system 100 may similarly be designed for m=1 or 2. In an embodiment having a single wavelength channel (m=1), certain optical elements shown in FIG. 1 might not be present. For example, optical multiplexers (MUXes) 116 and 140, optical de-multiplexers (DMUXes) 132 and 152, transmitter modules (Tx-i) 1122-112m, and receiver modules (Rx-i) 1562-156m may be omitted.

[0014]System 100 has a WDM transmitter 110 and a WDM receiver 150 optically coupled to one another via a fiber-optic link 102. Link 102 has two amplified fiber-optic sections 120a-b, each having one or more optical amplifiers (OAs) 124 and one or more runs of fiber. Link 102 further has a multi-channel optical phase conjugator 130 coupled between fiber-optic sections 120a-b as show