Open AccessBound electronic and free carrier nonlinearities in Silicon nanocrystals at 1550nm
Author(s) -
R. Spano,
N. Daldosso,
M. Cazzanelli,
L. Ferraioli,
Luca Tartara,
Jianhua Yu,
Vittorio Degiorgio,
E. Jordana,
J-M. Fédéli,
L. Pavesi
Publication year - 2009
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.17.003941
Subject(s) - materials science , refractive index , excitation , optics , excited state , silicon , absorption (acoustics) , two photon absorption , free carrier absorption , nonlinear optics , saturation (graph theory) , nanocrystal , z scan technique , optoelectronics , atomic physics , physics , laser , nanotechnology , mathematics , quantum mechanics , combinatorics
We present a detailed investigation of the different processes responsible for the optical nonlinearities of silicon nanocrystals at 1550 nm. Through z-scan measurements, the bound-electronic and excited carrier contributions to the nonlinear refraction were measured in presence of two-photon absorption. A study of the nonlinear response at different excitation powers has permitted to determine the change in the refractive index per unit of photo-excited carrier density sigma(r) and the value of the real bound-electronic nonlinear refraction n(2be) as a function of the nanocrystals size. Moreover at high excitation power, a saturation of the nonlinear absorption was observed due to band-filling effects.