Very High Frequency Self-Pulsation and Stable Optical Injection Locking for Well-Defined Multi-Electrode Distributed Feedback Lasers

Self-pulsating multi-electrode distributed feed back (DFB) lasers with two active DFB regions and a passive phase tuning region between them were fabricated by introducing well-designed index-coupled gratings and phase shift. Free running self-pulsation and optical injection locking at 40GHz were demonstrated for a device with detuned uniform gratings. Self-pulsation at a very high repetition of 275 GHz was experimentally confirmed for a device with a lambda/4 phase shift in the DFB region. Dual mode laser oscillation occurred for both cases and the Pulsating frequencies were determined by the wavelength separation of the two lasing modes. Numerical calculation of temporal behavior by solving traveling wave equations explained the observed optical spectra of the laser. Furthermore, based on the comparison between the calculated reflectivity spectra of individual DFB regions and the optical spectra of the laser, the origins of the lasing modes were determined.