Ehsan Naghizadeh Alamdari, Mostafa Sahrai, Reza Kheradmand, Mansour Eslami,
Volume 16, Issue 1 (1-2022)
Abstract
Cavity Solitons (CSs) in an injected broad-area semiconductor laser with intracavity saturable absorber exhibit phase noise free and high-contrast intensity oscillations in period-one dynamical state. The continuous-wave periodic intensity oscillation of the CSs has a frequency well beyond the relaxation oscillation frequency and can be regarded as a photonic microwave source. Here we numerically investigate the effect of linewidth enhancement factor on the dynamical characteristics of CSs in the period-one regime. We show that in a fixed injection amplitude, it has a key role in shifting the oscillation frequencies of the period-one CSs and that its effects strongly depend on the cavity detuning value.
Bita Azemoodeh Afshar, Akbar Jafari, Rahim Naderali, Mir Maqsood Golzan,
Volume 16, Issue 2 (7-2022)
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.
Mr. Moein Golestanifar, Dr. Mohammad Ali Haddad, Mr. Amir Namiq Hassan, Dr. Fatemeh Ostovari,
Volume 17, Issue 2 (6-2023)
Abstract
The spatial self-phase modulation (SSPM) method was used to study the nonlinear optical responses of hydraulic oil containing dispersed nanosheets of reduced graphene oxide (rGO), hydroxylated rGO (rGO-OH), and carboxylated rGO (rGO-COOH). The intensity-dependent number of observed symmetric diffraction rings was analyzed to estimate the samples' thermally induced nonlinear refractive indexes and lead to estimated thermo-optical coefficients. Based on the observed symmetric diffraction rings, the nonlinear refraction coefficient and thermo-optical coefficient of samples were estimated to be in the order of magnitude of 10-6 cm2/W and 10-2 K-1, respectively. The results indicated that the presence of rGO derivatives significantly enhanced the optical nonlinearity of hydraulic oil.
