2005/07/28 by J. He, W. Ji, G. H. Ma +6
Physics and Astronomy · #cond-mat.mtrl-sci
published as J. Phys. Chem. B 109, 4373 (2005) · 18 pages, 4 figures
arxiv created 2005/07/28 · arxiv updated 2009/12/01
We report the ultrafast and large third-order nonlinear optical properties of CdS nanocrystals (NCs) embedded in a polymeric film. The CdS NCs of 2-nm radius are synthesized by an ion exchange method and highly concentrated in the two layers near the surfaces of the polymeric film. The two-photon absorption coefficient and the optical Kerr coefficient are measured with laser pulses of 250-fs duration at 800-nm wavelength. The one-photon and two-photon figures of merit are determined to be 3.1 and 1.3, respectively, at irradiance of 2 GW/cm2. The observed nonlinearities have a recovery time of ~ 1 ps. The two-photon-generated free carrier effects have also been observed and discussed. These results demonstrate that CdS NCs embedded in polymeric film are a promising candidate for optical switching applications.