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Proceedings Paper

Optical nonlinearity of surface-modified PbS and CdxPb1-xS nanoparticles in the femtosecond regime
Author(s): He Ping Li; B. Liu; Chan Hin Kam; Yee Loy Lam; Wenxiu Que; L. M. Gan; C. H. Chew; G. Q. Xu
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Paper Abstract

We present an investigation of third-order optical nonlinearity in surface modified PbS and CdxPb1-xS nanoparticles using the Z-scan technique with femtosecond laser pulses at 780-nm wavelength. The samples include PbS nanoparticles in microemulsion with PbS concentration range from 0.3-2.5 X 10-3 M and CdxPb1-xS nanoparticles in microemulsion with x from 0 to 1. An extended Z-scan theory based on the Huygens- Fresnel princeps is employed to extract the nonlinear refraction index from the experimental Z-scan data with a large nonlinear phase shift. The nonlinear refractive index in PbS nanoparticle microemulsion is found to increase linearly with PbS concentration between 0.3 X 10-3 and 1.9 X 10-3 M. The highest concentration microemulsion gives a nonlinear refractive index of 1.8 X 10-11 cm2/W, which is approximately 4 orders of magnitude higher than those of commercially available bulk semiconductors, such as ZnS and CdS, measured at the same conditions. In CdxPb1-xS nanoparticles, Cd0.33Pb0.67S exhibits relatively larger refractive nonlinearity. For all samples, nonlinear absorption remained unmeasureable up to 0.9 GW/cm2. The observed large refractive nonlinearity in these nanoparticles may mainly be attributed to the optical Stark effect and contribution from the surface-trapped states in the nanoparticles.

Paper Details

Date Published: 9 November 1999
PDF: 8 pages
Proc. SPIE 3899, Photonics Technology into the 21st Century: Semiconductors, Microstructures, and Nanostructures, (9 November 1999); doi: 10.1117/12.369423
Show Author Affiliations
He Ping Li, Nanyang Technological Univ. (Singapore)
B. Liu, National Univ. of Singapore (Singapore)
Chan Hin Kam, Nanyang Technological Univ. (Singapore)
Yee Loy Lam, Nanyang Technological Univ. (Singapore)
Wenxiu Que, Nanyang Technological Univ. (Singapore)
L. M. Gan, National Univ. of Singapore (Singapore)
C. H. Chew, National Univ. of Singapore (Singapore)
G. Q. Xu, National Univ. of Singapore (Singapore)

Published in SPIE Proceedings Vol. 3899:
Photonics Technology into the 21st Century: Semiconductors, Microstructures, and Nanostructures
Seng Tiong Ho; Yan Zhou; Weng W. Chow; Yasuhiko Arakawa, Editor(s)

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