9 research outputs found
Photothermal Characterization of Nanogold Under Conditions of Resonant Excitation and Energy Transfer
We have performed thermal diffusion measurements
of nanofluid containing gold and rhodamine 6G dye
in various ratios. At certain concentrations, gold is nearly
four times more efficient than water in dissipating small
temperature fluctuations in a medium, and therefore it will
find applications as heat transfer fluids. We have employed
dual-beam mode-matched thermal lens technique for the
present investigation. It is a sensitive technique in measuring
photothermal parameters because of the use of a lowpower,
stabilized laser source as the probe. We also present
the results of fluorescence measurements of the dye in the
nanogold environment.Cochin University of Science and Technolog
Laser-induced Bessel beams can realize fast all-optical switching in gold nanosol prepared by pulsed laser ablation
We demonstrate the possibility of realizing, all-optical switching in gold nanosol. Two overlapping laser beams are used for this purpose, due to which a low-power beam passing collinear to a high-power beam will undergo cross phase modulation and thereby distort the spatial profile. This is taken to advantage for performing logic operations. We have also measured the threshold pump power to obtain a NOT gate and the minimum response time of the device. Contrary to the general notion that the response time of thermal effects used in this application is of the order of milliseconds, we prove that short pump pulses can result in fast switching. Different combinations of beam splitters and combiners will lead to the formation of other logic functions too.Cochin University of Science and Technolog
Thermal diffusivity of rhodamine 6G incorporated in silver nanofluid measured using mode-matched thermal lens technique
Dual beam mode-matched thermal lens method has been employed to measure the heat diffusion in
nanofluid of silver with various volumes of rhodamine 6G, both dispersed in water. The important observation
is an indication of temperature dependent diffusivity and that the overall heat diffusion is slower
in the chemically prepared Ag sol compared to that of water. The experimental results can be explained
assuming that Brownian motion is the main mechanism of heat transfer under the present experimental
conditions. Light induced aggregation of the nanoparticles can also result in an anomalous diffusion
behavior