Abstract: A multi-section semiconductor laser diode is disclosed. The laser diode includes a complex-coupled DFB laser section that includes a complex-coupled grating and an active structure for controlling the intensity of oscillating laser light, to oscillate laser light in a single mode, and an external cavity including a phase control section and an amplifier section, the phase control section having a passive waveguide that controls a phase variation of feedback laser light, the amplification section having an active structure that controls the strength of the feedback laser light. Currents are separately provided to the three sections to generate optical pulses with tuning range of tens of GHz. Applications include the clock recovery in the 3R regeneration of the optical communication.

Abstract: Disclosed is a high frequency optical pulse source generating stable optical pulses over a wide current range in an optical transmission system to enhance stability and reliability, the high frequency optical pulse source implementing, in one chip, a multi-section distributed feedback (DFB) laser diode with a phase control section arranged between two DFB laser diodes. By controlling the current applied to the electrode of the phase control section while applying currents to the first and second DFB sections, the present invention causes self-mode locking between the compound-cavity modes having similar threshold currents, thereby generating stable tens GHz-level optical pulses. Hence, the present invention generates optical pulses uniformly over a wide current range, thereby enhancing the stability and reliability of the element.