Leila Sarkhosh

Abstract: Stabilized gold nanoparticle (AuNP) colloids have been fabricated by nanosecond pulsed laser ablation of a pure gold plate in cyclohexanone. The AuNPs colloid exhibits a UV-Vis absorption spectrum with a surface plasmon absorption peak at about 540 nm. Scanning electron microscopy has shown the formation of spherical AuNPs with average size about 53 nm. The shift of 24 cm -1 is observed in the carbonyl band of the colloid using FTIR spectroscopy. This shift indicates that the monomer carbonyl group of cyclohexanone interacts with the surface of the AuNPs and leads to stabilizing the colloid. A large nonlinear refractive index of -2.92 x 10 -7 cm 2 /W is measured using the Z-scan technique under continuous wave laser irradiation at 532 nm. Our results show that the large induced nonlinear refraction is attributed to the surface plasmon resonance (SPR) enhancement effect of AuNPs, high thermo-optic coefficient and low thermal conductivity of cyclohexanone. Observation of far-field diffraction ring patterns confirm a thermally induced negative lens effect and spatial self-phase modulation in the laser beam as it traverses the colloids.

TL;DR: In this paper, the authors investigated the optical limiting performance of an Ag 2 S NP colloid under exposure to nanosecond pulsed laser irradiation at 532 nm and found that nonlinear scattering plays an important role in the limiting action of the sample.

TL;DR: In this article, the effect of the gold nanoparticle concentration on thermo-optical properties of colloidal gold nanoparticles was investigated using the Z-scan technique, which revealed that the heat diffusion in the colloids is due to nonlocal thermal process.

TL;DR: In this article, the characteristics of closed Z-scan in materials with a large nonlinear phase shift have been studied and a formula for the transmittance is derived, based on nonlocal heat effect and Fresnel diffraction theory.

TL;DR: In this paper, the effect of the thermal conductivity of the surrounding liquid environment on the thermal nonlinear refraction of gold nanoparticles (AuNPs) synthesized by laser ablation of a gold target in different solutions is investigated.