Abstract: An apparatus is provided for transmitting an optical signal. The apparatus includes an optical signal source for generating an optical signal having a plurality of optical channels onto which data is modulated at a plurality of predetermined frequencies to provide a plurality of optical data channels. An amplitude modulator is coupled to the optical signal source for modulating each of the optical channels with a waveform that is independently adjustable from one another. A clock, coupled to the amplitude modulator, has a plurality of frequencies that respectively determine the modulation frequencies imparted to the plurality of optical channels by the amplitude modulator. Each of the frequencies of the clock is phase locked and equal to its respective predetermined frequency at which is data is modulated.

Abstract: A method and apparatus is provided for modulating the polarization of an optical signal. A polarization modulator receives an optical signal onto which data has been modulated at a predetermined frequency. The polarization modulator modulates the state of polarization of the optical signal at a frequency phase locked and equal to the same predetermined frequency at which the data is modulated onto the optical signal. The polarization modulation is performed so that the average value of the state of polarization over each modulation cycle is substantially equal to zero.