http://personalpages.to.infn.it/~onorato/publications_files/2013_Onorato_etal_PhysRep.pdf

Rogue waves and their generating mechanisms in different physical contexts

Nonlinear optics of liquid crystalline materials

We describe the programmable spatial beam shaping of 100-kHz, 4-?J amplified femtosecond pulses in a focal plane by wave-front modulation. Phase distributions are determined by a numerical iterative procedure. A nonpixelated optically addressed liquid-crystal light valve is used as a programmable wave-front tailoring device. Top-hat, doughnut, square, and triangle shapes of 20-?m size are obtained in a focal plane. Their suitability for femtosecond laser machining is demonstrated.

Programmable focal spot shaping of amplified femtosecond laser pulses.

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) houses the world’s largest laser system, composed of 192 individual, 40-cm-aperture beamlines. The NIF laser ro...

Optics Recycle Loop Strategy for NIF Operations Above UV Laser-Induced Damage Threshold

Scientists in the UK have made a high-resolution optically addressed spatial light modulator (OASLM) based on zinc oxide (ZnO) nanoparticles. There is a strong demand for inexpensive OASLMs capable of producing high-resolution holograms over large active areas. The three researchers, who are all from the University of Cambridge, used a simple and inexpensive method to fabricate their OASLM — spin coating ZnO nanoparticles suspended in ethanol onto an indium–tin-oxide-coated glass substrate and then producing a photosensitive layer by low temperature (under 180 °C) annealing. The OASLM had a resolution of up to 825 lp mm−1 when operated at a voltage of below 6 V. The researchers attribute this performance to the use of a photoconductive film having a thin layer of semiconductor nanoparticles and a nematic liquid crystal with a relatively sharp threshold voltage.

/pdf/a-high-resolution-optically-addressed-spatial-light-5besucmk9m.pdf

A high-resolution optically addressed spatial light modulator based on ZnO nanoparticles

A new liquid crystal light valve (LCLV) is presented using bulk monocrystalline Bi12SiO20 (BSO) as both the photoconductive material and as one of the substrates supporting the liquid crystal layer. The photoconductive properties of the BSO under ac voltages are investigated. The device operates at room temperature with a low ac drive voltage (25-V ac at 500 Hz). These specific properties are explained from the aspect of an equivalent electrical circuit of the structure. A prototype BSO LCLV with a 15-μm liquid crystal thickness shows a 10-lp mm−1 spatial resolution. The device coherent modulation transfer function was measured experimentally and found to agree with theory. Typical writing energies are ~20 μJ cm−2 at wavelength λ = 450 nm.

Liquid crystal light valve using bulk monocrystalline Bi 12 SiO 20 as the photoconductive material

Liquid crystal light valve using bulk monocrystalline Bi 22 SiO 20 as the photoconductive material

The substrates which close the cell are, respectively, a glass plate and the bulk photoconductive BSO crystal (2 mm thick). The nematic liquid crystal (pentylcyanobiphenil PCB, 15 μm thick) is aligned by obliquely evaporating a thin film of silicon monoxide. Two transparent electrodes are layered to apply a longitudinal ac voltage. Information writing on the light valve is obtained with a source whose output wavelength corresponds to the optimum spectral sensitivity range of the BSO (λw≃450 nm). Visualization of the 2-D field distribution is obtained on the readout beam with crossed polarizers. Electrical behavior of the light valve under ac voltage operation is explained in terms of space charge limited currents through the BSO. The equivalent electrical circuit of the light valve will be derived from the BSO electrical impulse response under uniform illumination.

J. P. Huignard

Papers

Liquid crystal light valve using bulk monocrystalline Bi 12 SiO 20 as the photoconductive material

Liquid crystal light valve using bulk monocrystalline Bi 22 SiO 20 as the photoconductive material

Liquid crystal light valve using bulk mono-crystalline Bi12SiO20 as the photoconductive material