The on-coming photonic layer of CMOS integrated circuits needs efficient light sources to treat and transmit the flow of data. We develop new configurations of III-V/Si vertical cavity lasers coupled to silicon optical waveguides using mirror/coupler based on photonic crystals. These devices can be fabricated using fully CMOS-compatible technological steps. Using this approach, the optical gain is provided by the III-V material, while all the remaining part of the optical cavity is in silicon. The output coupling to the sub-ÃÂµm waveguides of the CMOS optical layer can then be inherently optimised since the laser mirror/coupler and the Si output waveguides will be realised together during the same fabrication step. It has been demonstrated that photonic crystals membrane can act as very efficient reflectors (PCM-mirrors) for vertical microresonators. In this communication, the design of a vertical cavity microlaser based on these PCM-mirrors will be presented. We will show that high Q-factors (>10000) along with strong vertical and lateral confinements can be achieved. As a first demonstration, experimental results on silicon PhC-mirrors and associated vertical cavities will be discussed, showing Q factors larger than 2000. Finally, theoretical results on the coupling between such cavities and a silicon micro-waveguide will be presented.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.