Method and system for a polarization mode dispersion tolerant optical homodyne detection system with optimized transmission modulation

A method of reducing the transmitted power of a quadrature modulated optical data signal, comprises the steps of:

• providing a quadrature modulated optical data signal by a transmitter;
• during all transitional states of the quadrature modulated optical data signal in which data symbols can change in value, reducing, by the transmitter, the power to zero such that transmitted power decreases to zero at approximately a mid point of each of the transitional states;
• combining the quadrature modulated optical data signal with a side carrier;
• and
• transmitting the side carrier with the quadrature modulated optical data signal.

An optical data signal transmitter comprising:

• a Mach-Zender modulator, the Mach-Zender modulator receiving an input optical signal and modulating a pair of side carriers onto the input optical signal, outputting an optical carrier signal;
• and
• at least two phase modulators, the at least two phase modulators receiving the optical carrier signal and each generating an optical data signal by modulating a pair of data signals onto at least two data bands;
• wherein the data bands are spread in frequency when modulated onto the optical carrier signal, the spreading causing an amplitude of the optical data signal to be reduced to zero during all transitional state between any pair of data symbol, in which the data symbols can change in value.

An optical data signal transmitter comprising:

• a Mach-Zender modulator, the Mach-Zender modulator receiving an input optical signal and modulating a pair of side carriers onto the input optical signal, outputting an optical carrier signal;
• at least two phase modulators, the at least two phase modulators receiving the optical carrier signal and each generating an optical data signal by modulating a pair of data signals onto at least two data bands;
• a second Mach-Zender modulator, the second Mach-Zender modulator imprinting the input optical signal with an identification code to generate a TX ID, the identification code including information concerning the transmitter;
• and
• a combiner, the combiner attaching the TX ID to the optical data signal;
• wherein the data bands are spread in frequency when modulated onto the optical carrier signal, the spreading causing an amplitude of the optical data signal to be reduced to zero during transitions between data symbols.

An optical data signal comprising:

• a Mach-Zender modulator, the Mach-Zender modulator receiving an input optical signal and modulating a pair of side carriers onto the input optical signal, outputting an optical carrier signal;
• and
• at least two phase modulators, the at least two phase modulators receiving the optical carrier signal and each generating an optical data signal by modulating a pair of data signals onto at least two data bands;
• wherein the data bands are spread in frequency when modulated onto the optical carrier signal, the spreading causing an amplitude of the optical data signal to be reduced to zero during transitions between data symbols;
• and
• wherein the pair of side carriers is modulated onto the input optical signal at both above and below a reference frequency of the input optical signal.

A method of reducing the transmitted power of a quadrature modulated optical data signal, comprising the steps:

• providing a quadrature modulated optical data signal by a transmitter;
• during all transitional states of the quadrature modulated optical data signal in which data symbols can change in value, reducing, by the transmitter, the power to zero such that transmitted power decreases to zero at approximately a mid point of each of the transitional states;
• and
• spreading orthogonal data signals onto two side carriers of an optical signal to obtain the quadrature modulated optical data signal.