Second Harmonic Generation in Silicon Based Heterostructures: The Role of Strain and Symmetry

Silicon is today the electronic material par excellence. Nevertheless the increasing demand for new, innovative and more efficient devices has driven scientists to explore new functionalities in Si-based materials. In silicon photonics the introduction of second-order nonlinearity by proper material engineering would be highly desirable. However a bulk second-order dipolar nonlinear optical susceptibility in Si is forbidden due to the bulk crystal centrosymmetry. Different approaches have been used to break this inversion symmetry: ...