Optical Nonlinearity Of Silicon-based Materials

The Si-based semiconductor materials with a large and fast optical nonlinearity will play a very important role in the future optoelectronic integration, a field that developing very quickly in recent years. Because strongly affected by the quantum confinement effect, nanometer-sized Si- based materials can improve its optical nonlinearity dramatically. This paper deals with the optical nonlinear theory and experiment of nanometer-sized and Si-based materials, as well as introduces the recent development and the promising future of the Si-based optoelectrons. Employing some experimental methods, we have studied the structure and the optical properties of absorption and nonlinearity of two kinds of samples: the nano-crystalline silicon (tic-Si) film and nc-Si/SiO, supperlattices. The major results list as following: (1 )the structure of nc-Si film and nc-Si/Si02 supperlattices are evaluated by means of the Raman scattering spectra; (2) the exciton nonlinear refractive index of nc-Si film is measured as n2=6.58 X I O~ esu with the pumping-detecting technique, and the bleaching absorption of exciton is observed; (3) The 3rd order nonlinear refractive index and nonlinear absorption coefficient of the nc-Si/Si02 supperlattices are measured as n2=l .67 X 106 esu, P =5.68 X 1 08cm!W by the Z-scan technique; (4) The 3rd..order nonlinear optical susceptibility of the nc-Si/Si02 supperlattices is obtained as /35.84X 1 O8esu with the degenerate fourave mixing(DFWM) technique. Moreover, the origin of the large nonlinear optical response of nanometer- sized Si-based materials is discussed in terms of the quantum confinement effect.