In this paper, we report monolithically integrated III-V quantum dot (QD) light-emitting sources on silicon substrates for silicon photonics. We describe the first practical InAs/GaAs QD lasers monolithically grown on an offcut silicon (001) substrate due to the realization of high quality III-V epilayers on silicon with low defect density, indicating that the large material dissimilarity between III-Vs and silicon is no longer a fundamental barrier limiting monolithic growth of III-V lasers on Si substrates. Although the use of offcut silicon substrates overcomes the antiphase boundary (APB) problem, it has the disadvantage of not being readily compatible with standard microelectronics fabrication, where wafers with on-axis silicon (001) substrates are used. We therefore report, to the best of our knowledge, the first electrically pumped continuous-wave (c.w.) InAs/GaAs QD lasers fabricated on on-axis GaAs/Si (001) substrates without any intermediate buffer layers. Based on the achievements described above, we move on to report the first study of post-fabrication and prototyping of various Si-based light emitting sources by utilizing the focused ion beam (FIB) technique, with the intention of expediting the progress toward large-scale and low-cost photonic integrated circuits monolithically integrated on a silicon platform. We compare two Si-based QD lasers with as-cleaved and FIB-made facets, and prove that FIB is a powerful tool to fabricate integrated Manuscript lasers on silicon substrates. Using angled facet structures, which effectively reduce facet reflectivity, we demonstrate Si-based InAs/GaAs QD superluminescent light emitting diodes (SLDs) operating under c.w. conditions at room temperature for the first time. The work described represents significant advances towards the realization of a comprehensive silicon photonics technology.Index Terms-Molecular beam epitaxy, quantum dots, semiconductor lasers, silicon photonics, focused ion beam. College London, where he is currently a Professor of semiconductor photonics. His research interests include the nanometer-scale engineering of low-dimensional semiconductor structures (such as quantum dots, quantum wires, and quantum wells) by using molecular beam epitaxy and the development of novel optoelectronic devices including lasers, detectors, and modulators by developing novel device process techniques. He has co-authored more than 300 papers in the area of semiconductor materials and devices.