FM Response of InGaAsP Buried Heterostructure Distributed Feedback Lasers and their Applications in Incoherent FSK Systems.

We report the measurements of Frequency Modulation (FM) response of InGaAsP buried heterostructure distributed feedback lasers and the system performance of a 1.7 Gb/s and a 622 Mb/s incoherent Frequency-Shift-Keying (FSK) systems using these lasers. The measured lasers include 1.55microns conventional DFB lasers, quarter-wave-shifted DFB lasers and multi-electrode DFB lasers. The thermal dips in FM response of lambda /4-shifted DFB lasers usually occur at the lower frequencies, compared with that of conventional (250microns long) DFB lasers. With appropriate bias, the multi-electrode DFB lasers show no dip in their FM response. Using a lambda /4-shifted DFB laser, we have achieved the receiver sensitivity of -32.5 dBm (-39.5 dBm) for a 1.7 Gb/s (622 Mb/s) incoherent Frequency-Shift-Keying (FSK) system.