Third-order nonlinear optical properties of colloidal Au nanorods systems: saturable and reverse-saturable absorption.

In this work, we present a study of the nonlinear absorption properties from different gold nanorod (NR) systems in aqueous suspension. The NRs were obtained with the bottom-up protocol by the seed-mediated growth method (SMG), using Ag(+) ions at different concentrations, and CTAB as surfactant. By using this method, aspect ratios between 2 and 5 were obtained.

Gasohol quality control for real time applications by means of a multimode interference fiber sensor.

In this work we demonstrate efficient quality control of a variety of gasoline and ethanol (gasohol) blends using a multimode interference (MMI) fiber sensor. The operational principle relies on the fact that the addition of ethanol to the gasohol blend reduces the refractive index (RI) of the gasoline. Since MMI sensors are capable of detecting small RI changes, the ethanol content of the gasohol blend is easily determined by tracking the MMI peak wavelength response.

A second monoclinic polymorph of {2,6-bis[(2,4,5-trifluoro-phen-yl)imino-meth-yl]pyridine-κN,N',N''}dichloridonickel(II).

The asymmetric unit of the title compound, [NiCl(2)(C(19)H(9)F(6)N(3))], contains one half-mol-ecule residing on a crystallographic twofold rotation axis. The title compound crystallizes in space group C2/c while the previously reported polymorph was reported in P2(1)/c [Baldovino-Pantaleón et al. (2006 ▶).

Time-resolved analysis of cavitation induced by CW lasers in absorbing liquids.

We present novel results on thermocavitation using a CW medium-power near infrared laser (lambda=975 nm) focused into a saturated copper nitrate saline solution. Due to the large absorption coefficient at the laser wavelength, the solution can be heated to its superheat limit (T(sh) approximately 270-300 degrees C). Superheated water undergoes explosive phase transition around T(sh) producing approximately half-hemispheric bubbles (gamma approximately 0.

Polarization-controlled contrasted images using dye-doped nematic liquid crystals.

We explore the polarization dependence of the nonlinear response of a planar nematic liquid crystal cell doped with 1% wt of methyl red dye. The results obtained show that the refractive index change can be switched from a positive value to a negative one as the polarization of the beam changes from parallel to perpendicular with respect to the rubbing direction. This property is exploited in a phase contrast system, where a dynamic phase filter is photoinduced in a liquid crystal cell placed in the system's Fourier plane.