Sub-5-ps optical pulse generation from a 1.55-μm distributed-feedback laser diode with nanosecond electric pulse excitation and spectral filtering

This paper reports generation of sub-5-ps Fourier-transform limited optical pulses from a 1.55-μm gain-switched single-mode distributed-feedback laser diode via nanosecond electric excitation and a simple spectral-filtering technique. Typical damped oscillations of the whole lasing spectrum were observed in the time-resolved waveform. Through a spectral-filtering technique, the initial relaxation oscillation pulse and the following components in the output pulse can be well separated, and the initial short pulse can be selectively extracted by filtering out the short-wavelength components in the spectrum. Short pulses generated by this simple method are expected to have wide potential applications comparable to mode-locking lasers.