Measurement for waveform and chirping of optical pulses generated by directly modulated DFB laser and external EA modulator

Optical pulse generated by directly modulated distributed feedback (DFB) laser and external electro-absorption modulator (EAM) in virtue of the method of fringe-resolved second-harmonic generation correlation was measured. Without the pulse's shape being assumed, through the method of iterative reconstruct interference signal, the waveform and phase of the pulse was reconstructed. The full-wave at half-maximum (FWHM) of the pulse generated by EAM under the microwave modulation of 2.5GHz is 30.8ps, whose shape is close to that of the sech2-type pulse. The FWHM of the pulse generated by DFB laser is 18.3ps, whose shape is close to that of the Lorenz-type pulse. And the original chirping of EAM is smaller than that of DFB laser.