The near- and off-resonant optical limiting properties of gold, silver and gold–silver alloy nanoparticles in methyl 2-methylprop-2-enoate for nanosecond laser pulses are presented. The nanoparticles are generated by picosecond pulsed laser ablation in liquid having hydrodynamic diameters from 26 to 30 nm. We use a Q-switched Nd:YAG laser working at a wavelength of 1064 or 532 nm, with a pulse width of 3 ns to characterize their behaviour by laser energy and fluence dependent transmittance measurements. To elucidate the contribution of nonlinear scattering to the optical limiting properties the scattered light energy at an angle of 90° is measured. The experimental results show that these nanoparticles have a strong nonlinear attenuation which can be attributed to intraband, interband and free carrier absorption and a thermal-induced scattering only at high input energies. Our results indicate in addition that the surface plasmon resonance does not contribute to the nonlinear processes at high input energies.

No abstract

The optical limiting behavior of silver nanoparticles with different sizes and shapes is investigated and compared to the optical limiting performance of conventional carbon black suspension (CBS). The optical limiting behavior is characterized by means of nonlinear transmittance and scattered intensity measurements when submitted to nanosecond pulsed Nd:YAG lasers operating at the fundamental or the second harmonic wavelength. We found that the optical limiting effect is strongly particle size dependent and the best performance is achieved with the smaller particles. Moreover, it is shown that the surface plasmon resonance is not the main effect responsible for the nonlinear processes. A theoretical model based on the computation of the Mie scattering functions is exposed, and it is shown that the experimental results can be well explained from the calculations.

Optical limiting tests on nanoparticles of different shapes found a mismatch between surface plasmon resonance absorption spectra and nonlinear transmission spectra.

No abstract