title: Enhanced optical nonlinearity in amorphous silicon and its application to waveguide devices.
abstract: We present the first measurements of optical nonlinearity due to free carrier effects in amorphous silicon films using z-scan technique, demonstrating enhanced nonlinearity due to existence of midgap localized states. We also introduce, fabricate and experimentally characterized a new composite waveguide structure consisting of amorphous and crystalline silicon. The fabricated composite rib waveguide confirms to have enhanced free-carrier nonlinearity at the estimated value of 4cm/GW, i.e., seven times larger than that of a crystalline silicon waveguide. Due to existence of the midgap localized states in amorphous silicon, the measured free-carrier lifetime in the composite rib waveguide was about approximately 300ps which is shorter than the values reported in the literature for similar geometries made of silicon.
authors: Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0409, USA. kazikeda@ucsd.edu
authors: Kazuhiro
authors: K
authors: Ikeda
authors: Yaoming
authors: Y
authors: Shen
authors: Yeshaiahu
authors: Y
authors: Fainman
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D003460:Crystallization / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D008956:Models, Chemical; D017711:Nonlinear Dynamics; D055096:Optical Devices; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D012825:Silicon / Q000737:chemistry*
chemical_list: D012825:Silicon