Chirped return-to-zero modulation by imbalanced pulse carver driving signals

We demonstrate a simple way of generating chirped and alternate-chirp return-to-zero signals of various duty cycles by means of a sinusoidally driven dual-drive Mach-Zehnder modulator. The amount of inherently bit-synchronized chirp is tuned by varying the imbalance of the drive signals´ amplitudes or their relative delay. High temporal resolution measurements of the intensity and phase of the modulated optical field are obtained at 20 and 40 Gb/s using the spectrogram technique.