The target of the present proposal is to demonstrate the feasibility of integrated optoelectronic devices in silicon. In particular, the optimisation of the performances of light sources, devices for signal handling (wave guides, optical amplifiers, switches, etc.) and detectors realised within VLSI-compatible Si technology will be carried out. Moreover, the possibility of integrating the different components within a single chip will be investigated. The achievement of such a goal would clearly have a strong industrial relevance. In fact this would allow the use of the mature and low cost Si technology to fabricate optoelectronic devices and would attract the attention of several silicon device industries. In particular, the possibility of a Si-based optoelectronics has attracted the interest of SGS-Thomson and, in case of success of the first phase, we anticipate the participation of SGS-Thomson in the project. The first phase of the project will be devoted to evaluate the potentiality of new approaches to realise the different optical functions (rare-earth and isoelectronic impurity doping of silicon for light emission, synthesis of optically doped thin films of oxides or ferroelectrics deposited on silicon for optical gain and switching, as well as advanced Schottky barriers on Si for detection, etc.). The results of this evaluation will clearly identify those methods which are best suited for efficient and Si VLSI compatible optical functions. In the second phase the performances of the different optical functions will be optimised and their integration with electronic functions in a single chip will be performed.