نشریه اپتوالکترونیک
سال دوم شماره 3 (پیاپی 7، زمستان 1396)

Holographic interferometry is one of the accurate methods for measuring physical quantities such as stress, pressure, vibration, and temperature and refractive index changes especially in transparent solid materials. In this study, a digital Mach-Zehnder holographic interferometry setup was used to measure the induced temperature changes by infrared laser irradiation in a polyethylmethacrylate cell. The obtained results from the interferometric method were in good agreement with the results of the measurement by a temperature sensor.

In this work, we report on update and automation of an old-fashioned interferometer by using image processing techniques and developing a Graphical User Interface (GUI) in the MATLAB environment. After updating the system and receiving the digital images of interference fringe patterns from the interferometer and their transfer to the MATLAB environment, the ability of image rotation, as a geometric operation, is provided in the GUI. Following the detection of the dominant noise in the received images, digital filters that best suited for their remove and image enhancement are identified. It is found that the two image processing filters, which have the best results in removing the noises, are the linear average and the nonlinear median filters. The possibility of chossing these two filters along with their corresponding neighborhoods are provided in the GUI. To automate the system and for machine vision detection of optical surface qualities, an algorithm is developed to detect the interference fringes and to determine the space between them. The accuracy of the algorithm and the developed GUI in measuring the quality of the optical elements is tested by using the known standard quality elements. It is found that the GUI is capable of measuring the optical quality with good precision.

In this paper the zero-dimensional nonlinear transport model is applied to obtain the energy and the densities of deuterium and tritium fuel ions, as well as the alpha-particles in fusion reactor for laser and magnetic confinement methods. In this work D-T fuel pllets with. KrF laser is used in laser confinement and ITER paremeters are considered for magnetic confinement fusion. In order to densities of these ions are considered separately. Also, unlike the previous works which used impurity injection to mitigate thermal excursions, this design exploits the ability to modulate the DT fuel mix to control the plasma heating. By moving the isotopic mix in the plasma away from the optimal 50:50 mix, the reaction rate is moderated and the alpha-particle heating is reduced to desired levels. The zero-dimensional simulation study is presented to compare the energy gain in two states of laser and magnetic confinements.

As a new approach based on a multiple scale perturbation theory, we have founded clearly that ionization in a hollow-core photonic crystal fiber filled by an ionizable gas leads to a soliton self-frequency blueshift, opposite to redshift due to Raman self-frequency. To analyze the hollow-core photonic crystal fiber under a general perturbation, we convert the problem into a system of ordinary differential equations which govern on the soliton parameters. It is worth comparing the results with those of Saleh et al [Phys.Rev.Lett. 107, 203902 (2011)] applying a variational perturbation method with a posteriori. We obtain just the same result with no posteriori.

In this paper, we have analytically investigated the TM surface waves (SWs) by using the first integral of Maxwell’s equations in a semi-infinite one-dimensional photonic crystal (1DPC) which is truncated with the self-defocusing uniaxial nonlinear cap layer. We have studied the considered 1DPC in two cases: a metamaterial PC case (which has been made of alternate left-handed and right handed layers) and a usual PC case. Our findings reveal that between these structures, only in metamaterial PC case the dispersion of nonlinear SWs can be controlled by changing of the intensity of the electromagnetic field at the surface of self-defocusing nonlinear cap layer. Also, by comparing our results with those of the attenuated total reflection (ATR) method in the linear regime, we found that they are in line with them.

By linearizing and using Floquet’s theorem Maxwell equations, continuity and momentum equations are solved. Dispersion relation (DR) of a two stream free electron laser (FEL) with a helical wiggler pump is obtained. The DR which shows coupling of all modes is derived with using a fluid approach. The DR was solved numerically and band widths of resonances are indicated. In this paper effect of the density and energy difference of two beams on picks of the growth rates and band width of resonances are verified.

If the dielectric between two superconductors of the Josephson junction is homogeneous the governing equation for the phase of the system can be described by the sine-Gordon equation. In this paper, we consider inhomogeneous dielectric medium, such that the dielectric constant is position dependent. Then, we derive the sine-Gordon equation correspondence of this system and find its analytical and numerical soliton solutions. We simulate the particle behavior of the soliton solutions, and finally, we show that they obey the Newtonian’s second law of motion.

In this paper, we have studied the equations describing the proposed experimental Hamiltonian of a single-molecule magnet Fe8. In this research, we used from coherent states in real parameter and Fayman path integral. These nonlinear equations fully described dynamic of this single-molecule magnet in Su (2) and Su (3) groups. The solutions of these equations are magnetic solitons (not calculated in this study). »Linear equations show that for this SMM, the mean square torque ( Quadrupole excitation) is not constant and its dynamic consists of two parts. One part, rotate around the classical spin vector and the other is related to changing the size of the quadrupole torque. The spin wave dispersion equation for dipole and quadruple branches is calculated for small linear excitations from ground state (vacuum). These equations show that, for dipole branch, the spin wave is damping away from the single-molecular magnet and oscillating and not damping for the quadrupole branch.