Efficient directly emitting high-power Tb3+:LiLuF4 laser operating at 587.5 nm in the yellow range.

We present, to the best of our knowledge, the most efficient solid-state laser directly emitting in the yellow spectral range. Without any nonlinear conversion steps, a Tb3+:LiLuF4 laser operates at a wavelength of 587.5 nm with an output power of 0.5 W and a record-high slope efficiency of 25% with respect to the absorbed pump power at 486.2 nm. Despite the detrimental influence of 4f-excited state absorption, this efficiency is comparable to those obtained by complex nonlinear methods to generate yellow laser emission. Our approach, in combination with the progress in laser diodes at the required pump wavelength, paves the way for the development of cost-efficient, robust, and easily manageable diode-pumped yellow laser sources.

Spectroscopic properties and continuous-wave deep-red laser operation of Eu3+-doped LiYF4.

Eu3+-doped LiYF4 is reexamined as a laser material for the visible spectral region. Polarized absorption and emission cross sections as well as the fluorescence lifetime are determined. Branching ratios and radiative lifetime are calculated within the theory of 4f-4f transition intensities, which takes into account the influence of an excited configuration of the opposite parity 4fN-15d. Continuous-wave laser operation at 702 nm is demonstrated with a maximum output power of 15 mW and a slope efficiency of 4.6% under pumping with a frequency-doubled Ti:sapphire laser at 393.5 nm.

Mode-locked laser operation of Indium-modified Yb:KY(WO4)2 single crystal.

We report the first pulsed laser operation of an Indium-modified Yb:KY(WO4)2 crystal. Indium incorporation enlarges the broadening of the Yb3+ optical bands, reduces crystal lattice parameters and increases n(p) refractive index. A KY0.8In0.07Yb0.13(WO4)2 crystal pumped at 981 nm with a Ti-sapphire laser in a SESAM modulated resonator produces at 300 K self-starting and stable mode-locking. The shortest laser pulses achieved were centred at λ = 1041.1 nm, have a duration of 96 fs with average power of 134 mW and repetition rate of 103.5 MHz (1.3 nJ/pulse).

White and full color upconversion film-on-glass displays driven by a single 978 nm laser.

White and full-color displays based on upconversion (UC) processes in multilayered NaLu1-x-yYbxTmy(WO4)2/NaLu1-x-zYbxHoz(WO4)2 films deposited on 20 × 20 mm² Pyrex glass substrates are demonstrated by scanning with a 978 nm focused beam from a diode laser. Moreover, spatially resolved red, green and blue pixels are selected by focusing the excitation light at different depths on three stacked films with compositions individually optimized for UC emission of each fundamental color. The highest temperature used in synthesis/deposition process was 580 °C allowing the use of glass substrates.

The use of artificial neural networks in electrostatic force microscopy.

The use of electrostatic force microscopy (EFM) to characterize and manipulate surfaces at the nanoscale usually faces the problem of dealing with systems where several parameters are not known. Artificial neural networks (ANNs) have demonstrated to be a very useful tool to tackle this type of problems. Here, we show that the use of ANNs allows us to quantitatively estimate magnitudes such as the dielectric constant of thin films. To improve thin film dielectric constant estimations in EFM, we first increase the accuracy of numerical simulations by replacing the standard minimization technique by a method based on ANN learning algorithms. Second, we use the improved numerical results to build a complete training set for a new ANN. The results obtained by the ANN suggest that accurate values for the thin film dielectric constant can only be estimated if the thin film thickness and sample dielectric constant are known.PACS: 07.79.Lh; 07.05.Mh; 61.46.Fg.