No abstract

Gold nanoparticles and polystyrene beads are very important to use in advanced nanoscopic optical trapping techniques to probe any biological system of interest. Multiple trapping of these particles with different diameters can be performed by an optical tweezers system employing dark soliton controlled by Gaussian pulse within a particular configuration of microring resonators. By controlling some parameters and input power of the system, dynamics of the tweezers can be tuned. Radiation pressure acting on the particles including gradient and scattering forces were theoretically measured as a function of normalized position from the center of the laser beam. In this work, the highest output signal in the form of potential well is recorded at 112.80 W corresponding to 1.6 mm wavelength. Sizes of the tweezers are found within the range of 20 nm and the highest value of the optical force is recorded at 895.70 pN. We have demonstrated that the gradient force component is dominant over particle size within Rayleigh regime, thus a good agreement with theory is found.

Note: Self Q-switched Nd:YVO4 laser at 914 nm Rev. Sci. Instrum. 83, 046110 (2012); 10.1063/1.4705996Thermal stress analysis of a Nd : Y V O 4 laser medium end pumped by a Gaussian beam Abstract. The thermal stress effect on various doping levels of yttrium vanadate crystal Nd:YVO 4 is investigated. Diode end-pumped source was used to obtain the input-output characteristics of the vanadate crystal. The laser performance of the low doping crystal is poor since the optical conversion efficiency is small and high threshold pump power. However the low Dopant crystal is not associated with thermal stress thus no thermal damage. Differently with higher concentration of Nd ions crystal, the laser performance is relatively high but it is accompanied with thermal damage which comprised of microcrack, microfracture and contamination. The high absorption on the doping ions with additional external impurities causes extra heat generation which leads to thermal fracture.

Effect of the properties of an intracavity heat spreader on second harmonic generation in vertical-external-cavity surface-emitting laser Abstract. Birefringent ND:YVO 4 pumped by diode laser with fundamental wavelength of 1064 nm was used to pump nonlinear KTP crystal. Quartz crystals having natural birefringent property namely quarter and half waveplates were conducted in conjunction with the bulk of KTP to enhance the nonlinear beam. The result showed that half waveplate have electrical to optical conversion efficiency of 15.6 mW/A as compared to quarter waveplate is only 8.74 mW/A. The threshold current for SHG is found 5.3 A with half waveplate and 5.9 A with quarter waveplate. The high performance shown by half waveplate is realized due to the good mode matching after converting the polarization state.

A method referred as Hydrogen Production by Infrared assisted Electrolysis (HyPIR) is presented in this work. Two graphite electrodes are immersed in electrolytic cell containing 0.517 g of NaCl and 7 ml of ethanol C2H5OH solution which act as supplements for a partial oxidation reaction. Erbium YAG laser with wavelength of 2.94 mm and 57.6 mJ energy per pulse at a pulse rate of 4 Hz is illuminated directly on the electrolytic solution. The irradiating light facilitates the dissociation of water by stretching the inter-atomic hydrogen-oxygen bonds in the electrolytic solutions and directly increase the rate of hydrogen yields.