Patent ID: 7466926

Claim:
A method of generating a return-to-zero (RZ) differential phase-shift-keyed (DPSK) optical signal comprising the steps of: generating a 3-level RZ drive signal; and driving a modulator with the 3-level RZ drive signal to generate the RZ-DPSK optical signal, wherein the step of generating the 3-level RZ drive signal includes the steps of: performing a logic AND operation on a differentially encoded data signal and a clock signal to generate a first 2-level drive signal, wherein the differentially encoded data signal is a binary signal having first and second binary states; performing a logic AND operation on an inverse of the differentially encoded data signal and the clock signal to generate a second 2-level drive signal; and differentially amplifying the first and second 2-level drive signals to generate the 3-level RZ drive signal, wherein each occurrence of a binary state in the differentially encoded data signal is represented in the 3-level RZ drive signal by a positive pulse or a negative pulse relative to a reference level.