Schematic of the -scan setup for recording the nonlinear absorption and scattering. A—aperture; S—sample; F1, F2, F3, and F4—Neutral density filters, D1, D2, and D3—detectors; BS—beam splitter; L1, L2, L3, and L4—lens.
UV-Vis absorption spectra of CdS nanocrystals.
XRD spectra of CdS nanocrystals.
(a) TEM picture of CdS nanocrystals. (b) HRTEM picture of CdS nanocrystals showing crystalline structure and diffraction pattern (inside picture).
Fluorescence and upconverted fluorescence spectra of the CdS nanocrystals.
(a) Open aperture -scan curves of the CdS nanocrystals collected with two detectors; detector 1 gives the transmitted light and scattering, and detector 2 gives the transmitted light without scattering with laser pulses. (b) Open aperture -scan curve of the CdS nanoparticles with laser pulses, and the solid line is the curve obtained by theoretical fitting.
(a). Scattering of CdS nanocrystals at three different forward angles with intensity (-position). (b) Snapshot of the transmitted beam showing the distribution of the scattering in transmitted light through the CdS nanocrystals.
Change in two-photon absorption coefficient with respect to concentration of CdS nanocrystals. , as estimated from the -scan data recorded with a nanosecond laser of pure DMF solvent is .
Log-log plot of the phase conjugate signal as a function of the intensity, CdS curve having a slope of and curve having a slope of .
Change in thermal nonlinear refractive index with respect to concentration of CdS nanocrystals.
Change in effective scattering coefficient with respect to concentration of CdS nanocrystals at two different intensities. The solid line is the curve obtained by fitting Eq. (7).
Transmitted light and scattering (detector 1) and transmitted light without scattering (detector 2) of CdS nanocrystals with respect to input fluence. Dashed line represents linear transmittance of 0.76 at and the solid line is the curve obtained by integrating Eq. (3).
Optical limiting threshold of CdS nanocrystals with respect to concentration, collected with detector 2.
Snapshot of circular optical fringes formed in the transverse plane to the beam propagation direction at high intensity.
Two-photon absorption coefficient , nonlinear scattering coefficient , scattering parameter , thermal nonlinear refractive index , and limiting threshold of CdS nanocrystals at different concentrations (at wavelength).
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