US Patent 7590358 Optical regenerative amplifier for binary phase shift-keying signals

There is provided an optical regenerative amplifier for regenerative amplification of a binary phase shift-keying (BPSK) sequence of optical signals having a predetermined time slot between any adjacent signals. The optical regenerative amplifier comprises a first delay interferometer, wherein an input sequence of BPSK signals is split between two arms of an interferometer, a relative delay by the time slot between the adjacent signals is introduced in one of the arms of the interferometer to produce two mutually anti-symmetric trains of amplitude shift-keying (ASK) signals; a discriminative limiting amplifier to amplify the said two trains of anti-symmetric ASK signals, wherein the amplification for the spaces is smaller compared to the amplification for the marks and the amplification for the marks is limiting; and a second delay interferometer, wherein the said two trains of anti-symmetric ASK signals are recombined, delayed, and interfered to reproduce a regeneratively amplified BPSK sequence of signals and to separate noise from the signals.