577 research outputs found
Crystal Morphology and Growth Rate of Naphthalene in Various Processes Involving Supercritical Carbon Dioxide
No full textUV photosensitivity in a Ta<sub>2</sub>O<sub>5</sub> rib waveguide Mach-Zehnder interferometer
No full textThe ultraviolet (UV) photosensitivity of Ta2O5 measured in a rib waveguide Mach-Zehnder interferometer (MZI) is reported. With a cumulative fluence of 72J/cm2 at a wavelength of 248nm incident upon one arm through a 3-mm-long window, the MZI exhibits a phase shift of 8pi radians at wavelength λ = 1.55µm, corresponding to a saturated refractive index change of 2.1 x 10-3. Real time measurements of the MZI output during exposure are given and the UV-induced refractive index change is found to be negative
Effect of sodium toluene sulfonate on the nucleation, growth and characterization of DAST single crystals
No full textSelf-phase modulation induced spectral broadening of ultrashort laser pulses in tantalum pentoxide (Ta<sub>2</sub>O<sub>5</sub>) rib waveguide
No full textSelf-phase modulation induced spectral broadening has been observed for ultrashort pulses propagating through Ta2O5 rib waveguide. The associated nonlinear refractive index was estimated to be 7.23 x10-19 m2/W, which is higher by one order of magnitude than silica glass
Sub-micron period grating structures in Ta<sub>2</sub>O<sub>5</sub> thin oxide films patterned using UV laser post-exposure chemically assisted selective etching
No full textThin polycrystalline films of Ta2O5 having high chemical resistance and large dielectric permittivity may be deposited by sputtering and have many applications in microelectronics and optoelectronics. A high-resolution and low-damage method for patterning relief structures in thin Ta2O5 films by chemically assisted UV laser selective etching is presented. The method is based in the initial exposure of the Ta2O5 films to pulsed UV radiation (quadrupled Nd:YAG laser at 266nm) at fluences below the ablation threshold, for the creation of volume damage in the exposed areas. Subsequent immersion of the exposed sample in a KOH solution results in selective etching of the UV-exposed areas, developing relief structures of high quality. Interferometric exposure was used for the patterning of such gratings with periods shorter than 500nm in films of thickness between 100nm and 500nm. The behaviour of the patterning process is studied using diffraction efficiency measurements, AFM and SEM scans. Diffraction efficiency increases by a factor of 66, compared to the undeveloped structure, were obtained for gratings exposed with 1000 pulses of 30mJ/cm2 energy density, which were developed in a KOH solution of 50% weight concentration at a temperature of 55°C for 165mins. The etching method presented is being applied to the fabrication of optical waveguide gratings for telecommunication applications. Potential development of 2-D photonic crystal structures using this process is under investigation
UV-written channel waveguides in Er<sup>3+</sup>-doped Bi<sub>2</sub>O<sub>3</sub>-based glass
No full textThe present paper describes the fabrication of optical channel waveguides in an Er3+-doped Bi2O3-based glass using direct laser writing with a UV beam at 244 nm. A buried positive refractive index change was achieved through this method and a description of the observed phenomena is given, based on optical and electron microscopy
A novel approach for recycling of kerf loss silicon from cutting slurry waste for solar cell applications
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