Gain-switching of 1.55 µm InP-based Qdash lasers grown on Si

Reliable lasers on Si with large bandwidth are desirable for high-performance data communication systems on Si-photonics platforms. Here, we report short optical pulses generated by gain-switched InP-based 1.55 µm quantum dash (Qdash) lasers directly grown on (001) Si. The laser performance and related physical parameters were investigated by carrying out a gain-switching test for lasers on both Si and native InP substrates. The shortest pulses obtained were 217 and 252 ps for the lasers on InP and Si, respectively. By varying the electrical bias and pulse duration systematically, the evolution of the generated optical pulse duration and peak power was studied. The impact of cavity size on the optical pulse was also examined. Parameters were extracted using established equations fitted with our measurement results to gain insight into the underlying physics and correlation with the observed behavior. The obtained results indicate that the pulse width is limited by the low differential gain and strong gain compression of the active material. Our results indicate that Qdash lasers on Si can demonstrate comparable performance to those on a native InP substrate and manifest its potential application in an Si-based photonics chip for optical on-chip communications.