Multi-Gigahertz Bandwidth FM Response of Frequency Tunable Two-Electrode DFB Lasers.

We have characterized the FM response of frequency-tunable two-electrode DFB leasers operating at 1.3 microns. Under certain bias conditions, an FM response of ~1 GHz/mA is flat over a range of modulating frequencies from 10 kHz to several hundred MHz. This region is followed by a shallow dip and a high-frequency relaxation resonance peak, allowing an overall 3-dB FM bandwidth of ~5 GHz. We believe this to be the widest FM bandwidth reported to date for such lasers.