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Third‐Order Optical Nonlinearities in Thin Films of CdS Nanocrystals
Author(s) -
Rakovich Yu.P.,
Artemyev M.V.,
Rolo A.G.,
Vasilevskiy M.I.,
Gomes M.J.M.
Publication year - 2001
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200103)224:1<319::aid-pssb319>3.0.co;2-o
Subject(s) - nanocrystal , materials science , refractive index , nanoparticle , nonlinear optical , z scan technique , shell (structure) , thin film , nonlinear optics , irradiation , nonlinear system , nanotechnology , optoelectronics , optics , laser , composite material , physics , quantum mechanics , nuclear physics
The non‐resonant nonlinear optical properties of CdS nanocrystals (NCs) embedded in silica (i) and forming matrix‐free (MF) almost close‐packed films (ii) were studied using the Z ‐scan technique. Among the group (i), samples containing NCs covered with a HgS and CuS shell were investigated. The highest value of the nonlinear refractive index n 2 = 1.85 × 10 —6 cm 2 /W was measured for the MF films. This number exceeds by far the value typical for bulk CdS and cannot be explained in terms of thermally induced nonlinearity. Strong enhancement of local fluctuations of the electro‐magnetic field in MF films where NCs form aggregates or clusters is suggested to explain this result. Within the group (ii), an enhancement of the nonlinearity was observed under pulsed irradiation for both CdS/HgS and CdS/CuS nanoparticles, compared to CdS NCs without a shell.