Method and apparatus for CRZ-DQPSK optical signal generation

1. An apparatus for generating a chirped return-to-zero (CRZ) differential quadrature-phase-shift-keyed (DQPSK) optical signal comprising:

means for generating a first return-to-zero (RZ) drive signal and a second RZ drive signal using a first tributary of a data signal;

modulator means driven by the first and second RZ drive signals for providing simultaneous RZ pulse formatting and chirped DPSK data modulation to an optical signal to generate a CRZ-DPSK optical signal;

means for generating a non-return-to-zero (NRZ) drive signal based on a second tributary of the data signal;

modulator means driven by the NRZ drive signal for receiving the CRZ-DPSK optical signal and phase shifting the CRZ-DPSK signal by 0 or π/2 to generate the CRZ-DQPSK optical signal.

2. An apparatus for generating a chirped return-to-zero (CRZ) differential quadrature-phase-shift-keyed (DQPSK) optical signal comprising:

means for generating a first pair of return-to-zero (RZ) drive signals using a first tributary of the data signal;

means for generating a second pair of RZ drive signals using a second tributary of the data signal;

modulator means driven by the first pair of RZ drive signals for providing simultaneous RZ pulse formatting and chirped DPSK data modulation to an optical signal to generate a first CRZ-DPSK optical signal;

modulator means driven by the second pair of RZ drive signals for providing simultaneous RZ pulse formatting and chirped DPSK data modulation to an optical signal to generate a second CRZ-DPSK optical signal;

means phase shifting the second CRZ-DPSK optical signal by π/2; and

means for combining the first CRZ-DPSK optical signal and the phase shifted second CRZ-DPSK optical signal to generate the CRZ-DQPSK optical signal.