Analysis of high-quality ultrashort pulse generation based on a dual-drive Mach-Zehnder modulator and chirp compensation

Abstract

This study reports on high-quality picosecond pulse generation using a single-stage dual-drive Mach-Zehnder modulator (DDMZM) and chirp compensation. Sinusoidal microwave signals with different amplitudes are sent to two RF ports of the DDMZM to form a pulse train and pulse compression is achieved by compensating for the linear frequency chirp with a single-mode fiber (SMF). Three parameters encompassing the power difference between two RF signals, the power of RF signals, and the bias point of the DDMZM that affect the pulse formation have been numerically studied. The optimum length of SMF used for chirp compensation is obtained by simulating the temporal propagation and evolution of the pulse in SMF and 3.56-ps chirp-compensated ultrashort pulses are realized at 1.55 µm with a 25-GHz repetition rate experimentally. Modulator-based flexible ultrashort pulse generation can be achieved easily by tuning the RF generator and light source, and customized high-quality pulses according to practical applications can be expected.