Open AccessEnhanced optical nonlinearity in amorphous silicon and its application to waveguide devices
Author(s) -
Kazuhiro Ikeda,
Yue Shen,
Yeshaiahu Fainman
Publication year - 2007
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.15.017761
Subject(s) - waveguide , materials science , amorphous silicon , silicon , amorphous solid , optoelectronics , optics , silicon photonics , crystalline silicon , physics , chemistry , organic chemistry
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.