Patent ID: 7057785

Claim:
Two-stage optical regenerator for regenerating a data signal comprising a series of optical pulses and having a predetermined bit period, the regenerator having first and second stages each comprising: (i) a modulator for modulating a reference signal with an input signal; and (ii) an interferometer for causing the modulated reference signal to interfere with another version of the modulated reference signal delayed by less than one bit period of the data signal to regenerate the input signal; in which the input signal of the modulator of the first stage of the regenerator comprises the data signal, and the input signal of the modulator of the second stage of the regenerator comprises the output from the first stage of the regenerator, wherein relative phase offsets are induced at the outputs of the two interferometers of the regenerator to obtain a condition selected from: a. minimum transmission from each of the interferometers by the maximum power levels of the respective input signals transmitted therethrough; and b. maximum transmission from the interferometer of the first stage by the maximum power level of the data signal, and minimum transmission from the interferometer of the second stage by the minimum power level of the output from the first stage of the regenerator; and wherein the first stage of the regenerator comprises a semiconductor optical amplifier coupled to a Mach-Zehnder interferometer having a relative delay of less than one bit period of the data signal between its arms, the data signal at a first wavelength within the gain band of the semiconductor optical amplifier and the reference signal comprising a continuous wave at a second wavelength, also within the gain band of the semiconductor optical amplifier, being coupled to the semiconductor optical amplifier.