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Title: Optical nonlinearities of colloidal InP@ZnS core-shell quantum dots probed by Z-scan and two-photon excited emission

Spectrally resolved nonlinear optical properties of colloidal InP@ZnS core-shell quantum dots of various sizes were investigated with the Z-scan technique and two-photon fluorescence excitation method using a femtosecond laser system tunable in the range from 750 nm to 1600 nm. In principle, both techniques should provide comparable results and can be interchangeably used for determination of the nonlinear optical absorption parameters, finding maximal values of the cross sections and optimizing them. We have observed slight differences between the two-photon absorption cross sections measured by the two techniques and attributed them to the presence of non-radiative paths of absorption or relaxation. The most significant value of two-photon absorption cross section σ{sub 2} for 4.3 nm size InP@ZnS quantum dot was equal to 2200 GM, while the two-photon excitation action cross section σ{sub 2}Φ was found to be 682 GM at 880 nm. The properties of these cadmium-free colloidal quantum dots can be potentially useful for nonlinear bioimaging.
Authors:
; ; ;  [1]
  1. Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland)
Publication Date:
OSTI Identifier:
22499222
Resource Type:
Journal Article
Resource Relation:
Journal Name: APL Materials; Journal Volume: 3; Journal Issue: 11; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION; CADMIUM; COMPARATIVE EVALUATIONS; CROSS SECTIONS; EXCITATION; FLUORESCENCE; INDIUM PHOSPHIDES; LASERS; OPTICAL PROPERTIES; PHOTONS; QUANTUM DOTS; ZINC SULFIDES