Spatio-temporal dynamics of a multi-section tunable laser with and without optical injection

Optically-injected semiconductor lasers have been investigated for many years. The attention has nowadays shifted towards multi-section lasers as they provide new kinds of applications. Recently, an improved travelling-wave (TW) method for simulation of multi-section lasers was presented in which spatio-temporal effects were included. An automated analysis tool was presented for the simulated data to distinguish between different states of dynamics outside the locking bandwidth as this was not possible before. Here, a three-section tunable laser, with and without optical injection, is simulated with the improved TW method and two new results are found. Firstly, the penetration depth of the optical power inside the DBR section of a solitary threesection laser strongly depends on its position on the tuning characteristic curve. It is shown that even with a small variation of the carrier density in the tuning region a large variation of the penetration depth can be observed and, hence, the optical power emitted out of the grating section changes significantly. Secondly, the dynamics of an opticallyinjected tunable laser for middle and high injection strengths are presented and it is demonstrated that the locking bandwidth becomes symmetric around zero detuning and new regions of higher-order instabilities appear outside the locking region. © 2010 SPIE.