title: Strain dependence of the nonlinear optical properties of strained Si nanoparticles.
abstract: We report on the lattice strain dependence of the nonlinear optical (NLO) parameters of strained Si nanoparticles (NPs), which are prepared in a controlled way by a mechanical ball milling process. X-ray diffraction analysis shows that the nature of strain is compressive and is primarily caused by milling-induced lattice dislocations, which is further supported by high-resolution transmission electron microscopy imaging. It is found that the nonlinear refractive index (n₂) and nonlinear absorption coefficient (β) are strongly influenced by the associated lattice strain present in Si NPs. With the increase of lattice strain, the β gradually decreases while n₂ increases slowly. The strain-dependent observed changes in the NLO parameters of Si NPs are found to be advantageous for application purpose, and it is explained on the basis of strain-induced modification in the electronic structure of the highest occupied molecular orbital and lowest unoccupied molecular orbital states of Si NPs. These results demonstrate the potential of strain-dependent enhancement of nonlinearities for silicon photonics applications.
authors: Soumen
authors: S
authors: Dhara
authors: Kenji
authors: K
authors: Imakita
authors: P K
authors: PK
authors: Giri
authors: Minoru
authors: M
authors: Fujii