Zero-Chirp Return-to-Zero Pulses Generation with Two Single-Driver z-Cut Mach--Zehnder Modulators

A novel method is proposed to suppress the frequency chirp of single-driver z-cut Mach--Zehnder modulators. Theoretical analysis shows that by multiplying the output pulses of a half clock frequency driving single-driver z-cut modulator with the one delayed odd multiple bit duration, the frequency chirp can be removed entirely, and return-to-zero (RZ) pulses with duty cycles of about 25% and 56% are obtained. An experimental scheme is proposed to validate the proposed method. The experimental results show that perfect 40GHz zero-chirp RZ pulses can be obtained by using this scheme.