The key material used in manufacturing electronic chips, Silicon (Si), is not a good photonic material since it is a poor light emitter with negligible electro-optic effect. For this reason, the expensive technology of III-V compound semiconductors (like GaAs or InP, with superior optical performances) have been almost exclusively used in the business of optoelectronic devices. However, if photonics is ever to find its way onto a disruptive low cost technology, silicon-compatible (CMOS-compatible) approaches of integrating electrical and optical functionalities on a Si chip need to be investigated.

In this talk I will give a panoramic overview of my research activity on Silicon Photonics at MIT. The research is aimed to engineer potential new solutions for CMOS-compatible light emission and light control in silicon-based systems of reduced dimensionality, where both quantum confinement and surface chemistry effects start to play a crucial role in the optical properties of the materials. I will review the main results obtained along two closely related research directions: the use of nano-sized silicon to achieve efficient light emission and optical amplification and the possibility to control and manipulate light states in silicon-based photonic structures. In particular, I will introduce the potential of Silicon nanocrystals (Si-nc) embedded in SiOx and SiNx dielectric matrices for efficient light emission, electrical injection and energy coupling (sensitization) with rare earth ions, specifically Erbium ions emitting at 1.55 microns. In addition, I will show how light emission can be enhanced by embedding Si-nanostructures into a-periodic photonic structures with significant field-enhancement effects and strong light-matter coupling. The case of SiNx/SiO2 a-periodic superlattices with multiple wavelength light emission enhancement will be presented.

Dr. Luca Dal Negro is a postdoctoral research fellow at the MIT. He obtained his Ph.D. degree in Physics from the University of Trento in Italy, studying stimulated emission and photon diffusion in low dimensional silicon structures. His work has demonstrated optical emission and gain from silicon, widely considered to be impossible due to its indirect band gap. His current work is on linear and nonlinear optics of semiconductor nanostructures, (Si nanocrystals, Si nitride structures and semiconductor quantum dots), energy coupling phenomena in rare earth atoms and semiconductor quantum dots, sputtering and PE-CVD deposition of Si-based materials, fabrication and characterization of photonic crystals structures and physics of optical quasicrystals. Dr. Dal Negro has 43 publications, including 6 invited papers and 5 book chapters.