In this experimental study, which was carried out in photonics laboratory at Strathclyde University, UK, dynamics of a multi-Quantum well semiconductor active medium laser, was studied. This is in order to study its emission stability and pulse shape development under the influence of strong optical feedback level with different deriving currents, in the free space transmission medium. An external stable resonator was constructed by inserting high reflectivity dielectric mirror outside the laser output, 20 cm apart from it, which is an extralarge external cavity. Controlling the reflected back optical power was done by using a nonpolarized (50:50) beam splitter. The external resonator supported by focusing (plano-convex) lens in order to make it stable. Laser translated from stable emission when it was solitary, to quasi-static, and low fluctuated, behaves, to be coherence collapse. This is due to the strong (50%) level of optical feedback.
The aim of the current study is the investigation of tensile behavior of the semi - crystalline polymers : polypropylene (PP ) , high density polyethylene(HDPE) and low density polyethylene (LDPE) . The energy to break or deformation was determined as a function of extension rates , ( PP) was break at extension rate (5) mm/min but (HDPE) break at higher extension rates (25) mm/min while( LDPE) not break even at very high extension rates but it is deformation or failure .
Compounds from tin oxide doped with gallium oxide and cerium oxide were synthesized. Thin films from (SnO2:Ga2O3,CeO2) with different doping ratios were prepared on glass and single crystal silicon as substrates with the use of the pulsed laser deposition technique. The results of FTIR spectrums analysis was presented. Varies heterojunctions were fabricated from (SnO2:Ga2O3,CeO2 /Cu2S/c-pSi) heterojunctions solar cell which are formed from two layers: the first was Cu2S and the second was layer from tin oxide doped with two oxides named gallium oxide and cerium oxide with different doping ratios (0, 0.03, 0.05, and 0.0
... Show MoreIn this research an analysis for improving the fatigue behavior (safety factor of fatigue) of non- articular prosthetic foot (SACH) in the region (Bolt Adapter).The laser peening was carried to the fatigue specimens to improving the fatigue properties of bolt’s material. The tests of mechanical properties and fatigue behavior were carried for material that the bolt manufacture from it, a region where the failure occur and inserted of these properties to the program of engineering analysis (Ansys) to calculate the safety factor of fatigue. The results showed that the safety factor after hardening by laser is increased by 42.8%.
In this work, enhancement to the fluorescence characteristics of laser dye solutions hosting highly-pure titanium dioxide nanoparticles as random gain media. This was achieved by coating two opposite sides of the cells containing these media with nanostructured thin films of highly-pure titanium dioxide. Two laser dyes; Rhodamine B and Coumarin 102, were used to prepare solutions in hexanol and methanol, respectively, as hosts for the nanoparticles. The nanoparticles and thin films were prepared by dc reactive magnetron sputtering technique. The enhancement was observed by the narrowing of fluorescence linewidth as well as by increasing the fluorescence intensity. These parameters were compared to those of the dye only and the dye solution
... Show MoreThis study successfully synthesized high-performance photodetectors based on Ag-WO3 core–shell heterostructures using a simple and economical two-step pulsed laser ablation in water method and has investigated the electrical characteristics of the Ag@WO3 nanocomposite heterojunction. The Hall effect tests indicate that the synthesized Ag@WO3 exhibits n-type conduction with a Hall mobility of 1.25 × 103 cm2V-1S-1. Dark current–voltage properties indicated that the created heterojunctions displayed rectification capabilities, with the highest rectification factor of around 1.71 seen at a 5 V bias. A photodetector’s responsivity reveals the existence of two response peaks, which are situated in the ultraviolet and visible region. The ph
... Show MoreCoronary artery disease (CAD) is a condition of an inadequate supply of oxygenated blood to a portion of the myocardium. It typically occurs when there is an imbalance between supply and demand of myocardial oxygen. The most common cause of myocardial ischemia is atherosclerotic disease of an epicardial coronary artery or arteries which is sufficient to cause a regional reduction in myocardial blood flow and inadequate perfusion of the myocardium supplied by the involved coronary artery. Fifty CAD subjects (23 females and 27 males) were enrolled in this study in addition to thirty healthy control subjects (13 female and 17 male). This study aimed to measure the serum levels of interleukin IL- 33, C- reactive prot
... Show MoreThe microwave induced plasma jet (MIPJ) system was built using local materials and based on a tapered waveguide. The parameters of this plasma were determined like electron temperature Te, electron density ne. the other parameters such as plasma frequency( fp), the Debye length( λD), and the number of particles in the Debye sphere( Nd) It has also been studied. The study were done at different Ar flow rate ranging from (2-10) l/m and a discharge tube diameter ranging from (2-10) mm. all of these parameters were determined depending on the MIPJ spectrum. it turned out that there is a high possibility of controlling the parameters of MIPJ through manipulating these parameters.
All-optical canonical logic units at 40 Gb/s using bidirectional four-wave mixing (FWM) in highly nonlinear fiber are proposed and experimentally demonstrated. Clear temporal waveforms and correct pattern streams are successfully observed in the experiment. This scheme can reduce the amount of nonlinear devices and enlarge the computing capacity compared with general ones. The numerical simulations are made to analyze the relationship between the FWM efficiency and the position of two interactional signals. © 2015 Chinese Laser Press
Dielectric barrier discharges (DBD) can be described as the presence of contact with the discharge of one or more insulating layers located between two cylindrical or flat electrodes connected to an AC/pulse dc power supply. In this work, the properties of the plasma generated by dielectric barrier discharge (DBD) system without and with a glass insulator were studied. The plasma was generated at a constant voltage of 4 kV and fixed distance between the electrodes of 5 mm, and with a variable flow rate of argon gas (0.5, 1, 1.5, 2 and 2.5) L/min. The emission spectra of the DBD plasmas at different flow rates of argon gas have been recorded. Boltzmann plot method was used to calculate the plasma electron temperature (Te), and Stark broadeni
... Show MoreFe, Co and Sb nanopowders were fruitfully prepared by electrical wire explosion method in Double distilled and de-ionized water (DDDW) media. The formation of iron, cobalt and antimony (FeCoSb) alloy nanopowder was monitored by X-ray diffraction. The x-ray diffraction pattern indicates that there are iron, cobalt and antimony peaks. Optical properties of this alloy nanoparticles were characterized by UV-Visible absorption spectra. The absorption peak position is shifted to the lower wavelengths when the current increases. That means the mean size of the nanoparticles controlled by changing the magnitude of the current. The surface morphological analysis is carried out by employing Scanning Electron Microscope (SEM). Particles with varies
... Show More