Bita Azemoodeh Afshar, Akbar Jafari, Rahim Naderali, Mir Maqsood Golzan,
Volume 16, Issue 2 (Summer-Fall 2022)
Abstract
In this study, we investigated the production of silver nanoparticles by pulsed Nd: YAG laser ablation with λ=532nm in distilled water. The sodium citrate used to control the size of nanoparticles (Nps). The sample containing Ag NPs was characterized by linear absorption spectroscopy (UV-Visible spectroscopy) and transmission electron microscopy (TEM observation). The behavior of nonlinear optical properties of silver nanoparticles was studied using the Z-Scan method at two optimum numbers of the laser pulses and four optimum laser energy densities. In the Z-Scan method, the nonlinear thermal properties of Ag NPs were investigated under exposure to nanosecond laser pulse at λ=532nm. They were gained by fitting theoretical and experimental data. The values of the nonlinear refractive index (n2) and the nonlinear absorption coefficient (β ) were compared concerning to two optimum numbers and four optimum energy densities. The results of the nonlinear refractive index showed a negative value for each sample, this means that samples act as a divergent lens, and the thermal self-defocusing effect can be the main factor of nonlinear behavior. Following the comparison of two quantities, n2 and β , we found that the nonlinear refractive index increased when the number of laser pulses light increased. In addition, the nonlinear absorption coefficient decreased when the number of laser pulses light increased. As a result, the application of these Ag NPs for optical switching devices was investigated, which demonstrated that the large Ag NPs are applicable tools for optical switching devices.
Erfan Abbaszadeh Jabal Kandi, Khosro Mabhouti, Rahim Naderali, Neda Samadzadeh,
Volume 17, Issue 1 (Winter-Spring 2023)
Abstract
In this article, the conditions of pulse production in two mutually coupled lasers are studied. Based on the obtained characteristic equation and its roots, the dynamical behavior of the system and the threshold of the instability are analyzed. For the stable operation of the system and with the use of the time series curves, it is possible to study the dynamical behavior and the stability ranges of the laser in the presence of the saturable absorber and the gain environment. This paper aims to achieve from quasi-periodic behavior in a solitary laser to the generation of a pulse train from two mutually coupled lasers in the presence of saturable absorbers. Also, the stability range for a solitary laser and then for two coupled lasers in the presence of saturable absorbers have been studied.
