Measurement of the gain in a XeF (C->A) laser pumped by a coaxial e-baim

A XeF (C→A) excimer laser with a specific output energy of 1.4 J/l has been demonstrated. The laser was pumped by a coaxial c-beam with an intermediate pulse length (≈ 175 ns) and pumping rate (~ 1 MW/cm3). The small signal gain in this system was measured at λ = 488 nm for different gas compositions and under various pumping conditions. A peak gain of 3.3% cm-1 was found in the usual five component gas mixture

Variable profiles of plasma pulses generated from high-k dielectric barrier discharge

With a specific design of a high-k dielectric barrier discharge, we observed plasma pulses with variable spatial profiles as a consequence of excitation by a high-voltage pulse at different pressures. The dependence of the profile of the generated plasma pulses on the charging voltage and the operating gas (air) pressure is described and the description of their temporal and spatial build-up mechanism is given. We demonstrate that the profile variation of the plasma pulses is caused by the co-existence of dipole switching-based electron emission and field electron emission from triple junctions. Finally, we propose a scheme describing the interaction of these two electron emission mechanisms that leads to the pressure dependence of plasma pulse profile

Stoichiometry controlled oxide thin film growth by pulsed laser deposition

The oxidation of species in the plasma plume during pulsed laser deposition controls both the stoichiometry as well as the growth kinetics of the deposited SrTiO3 thin films, instead of the commonly assumed mass distribution in the plasma plume and the kinetic energy of the arriving species. It was observed by X-ray diffraction that SrTiO3 stoichiometry depends on the composition of the background gas during deposition, where in a relative small pressure range between 10−2 mbars and 10−1 mbars oxygen partial pressure, the resulting film becomes fully stoichiometric. Furthermore, upon increasing the oxygen (partial) pressure, the growth mode changes from 3D island growth to a 2D layer-by-layer growth mode as observed by reflection high energy electron diffraction

Compact capacitively coupled N2 laser with a new electrode design

Lasing in N2 at 337 nm was achieved in a capacitively coupled discharge device having a cylindrical discharge volume with a length of 50 mm and a diameter of 3 mm. The cylindrical dielectric electrodes provide a nearly constant initial electric field throughout the discharge volume. Laser pulses with a width of 2.5 nsec (FWHM) and energy of 8 µJ were obtained

Extending on-chip supercontinuum generation in Si3N4 throughout the blue wavelength range

The broad coherent optical spectra obtained by supercontinuum generation (SCG) are of significant importance for applications in, e.g., spectroscopy, biology and precision metrology. Of particular interest is SCG using integrated optical waveguides fabricated from stoichiometric silicon nitride (Si3N4) with low-pressure chemical vapor deposition because this provided, so far, the broadest supercontinuum on a chip [1], reaching down into the blue wavelength range at 470 nm, using infrared pump lasers [2]. We investigate the extension of this percontinuum further toward the ultraviolet via dispersion engineering and shorter pump wavelengths. In current experiments, we use the waveguides without their SiO2 top cladding for reshaping the generated spectra. The goal is to shift the zero-dispersion wavelength to below 800 nm, such that a femtosecond Ti:Sa laser can be used as a pump