SYNCHRONOUS POLARIZATION AND PHASE MODULATION USING A PERIODIC WAVEFORM WITH COMPLEX HARMONICS FOR IMPROVED PERFORMANCE OF OPTICAL TRANSMISSION SYSTEMS

摘要

A method and apparatus is provided that yields improved performance bymodulating the optical phase and polarization of an optical signal with a periodicwaveform having harmonic content that is more complex than that associated with asimple sinusoidal waveform. A phase modulator receives an optical signal onto whichdata has been modulated at a predetermined frequency. The phase modulatormodulates the phase of the optical signal in a continuous manner with the periodicwaveform with complex harmonics where the fundamental phase modulationfrequency is equal to the same predetermined frequency at which the data ismodulated onto the optical signal. In another illustrative embodiment of theinvention, a polarization modulator further processes the optical signal by modulatingthe state-of-polarization of the signal in a continuous fashion with the periodicwaveform with complex harmonics where the fundamental polarization modulationfrequency is equal to the same predetermined frequency at which the data ismodulated onto the optical signal. In addition to being continuously modulated, thepolarization modulation is performed so that the average value of the state ofpolarization over each modulation cycle is substantially equal to zero.