Mrs Marzieh Nadafan, Prof. Rasoul Malekfar, Mrs. Zahra Dehghani,
Volume 8, Issue 2 (7-2014)
Abstract
Polyurethane closed cell (PUCC)/SiO2 nanocomposites have been prepared by using in situ polymerization approach. The third-order optical nonlinearities of PUCC/SiO2 nanocomposites, dissolved in DMF are characterized by Z-scan technique at the measurement wavelength of 532 nm. The nonlinear refractive (NLR) indices and nonlinear absorption (NLA) coefficients of samples were calculated from closed and open aperture Z-scan in the order of 10-8 with negative sign and 10-5 , respectively. The origin of optical nonlinearity in this case may be attributed due to the presence of two photon absorption (TPA) effect. The synthesized samples were examined by optical microscopy, SEM imaging and Raman spectroscopy. All the results related to NLO properties, suggest that PUCC/SiO2 may be a promising candidate for the application to optical limiting in the visible region.
Farshad Khoshnood, Mohammad Sabaeian,
Volume 17, Issue 1 (1-2023)
Abstract
The authors report on the impact of electrode doping on the optical and electrical properties of argon flash lamps. In this work, the lamps are made using borosilicate glass tubes with an outer diameter of 6 mm and a discharge distance of 35 mm. In the construction of the lamps, five types of tungsten electrodes doped with thorium at two different percentages, cerium, lanthanum as well as pure tungsten are used. Properties such as threshold voltage, light intensity, tube temperature, and flash time profile at various argon pressures are measured. The results indicated that, first, the threshold voltage is a linear function of gas pressure inside the tube. Second, the lamp with 1.7%-2.2% thorium doped tungsten cathode showed a lower threshold voltage, higher light intensity, and lower temperature rise at continuous wave operation. These characteristics of electrodes doped with thorium make them an appropriate option for use in the fabrication of argon flash lamps.
