Optical short pulse generation by a DFB laser/EA modulator integrated light source

A simulation of optical short pulse generation using a DFB laser/EA modulator integrated light source was carried out. The dependence of the pulse shape and the spectrum on the isolation resistance between laser and the modulator part is clarified. Theoretical results show that the spectrum is affected more seriously than the pulse shape by the isolation resistance. An isolation resistance of larger than 500 ω is required for transform-limited pulse generation. Utilizing an integrated light source with an isolation resistance of 10 Mω optical short pulse generation at 5 GHz repetition rate was experimentally obtained with a pulsewidth of 33 ps and with a spectral bandwidth of 9.4 GHz. Since the time-bandwidth product was 0.31, the pulse was considered to be quasi-transform-limited. The lasing wavelength stability during short pulse generation was also confirmed in the integrated light source.