Patent ID: 7734190

Claim:
A system for generating an optical return-to-zero signal, the system comprising: a coding device configured to receive an input electrical non-return-to-zero signal and generate a coded signal, the coded signal being associated with the electrical non-return-to-zero signal by modulo-2 addition, the coded signal being split into a first signal and a second signal; a time delay device configured to receive the second signal and generate a third signal, the third signal being delayed with respect to the second signal by a predetermined period of time; a driver configured to receive the first signal and the third signal and generate a driving signal, the driving signal being associated with a difference between the first signal and the third signal; a continuous wave (CW) laser configured to generate a light; an electro-optical modulator configured to receive the light and the driving signal, modulate the light with the driving signal, and generate an output optical signal; wherein: the driving signal includes a plurality of pulses, each of the plurality of pulses representing a logic high level; each of the plurality of pluses is associated with a first 180-degree phase shift from a first nearest one of the plurality of pulses, the first nearest one of the plurality of pulses preceding the each of the plurality of pluses; the each of the plurality of pluses is associated with a second 180-degree phase shift from a second nearest one of the plurality of pulses, the second nearest one of the plurality of pulses following the each the plurality of pulses; the predetermined period of time corresponds to a number of bit periods, the number of bit periods being a positive number; the output optical signal is an optical return-to-zero signal; the output optical return-to-zero signal is substantially free from any frequency chirp.