In a series of experiments we explore various aspects of femtosecond pulse shaping by coherent filters engraved in a persistent spectral hole burning (PSHB) material. We have in mind the coherent control of quantum systems, with high resolution and large number of addressable spectral points. We examine the phase correction efficiency of this approach, relying on Fourier transform spectral interferometry techniques to characterize the coherent filter. Two different PSHB materials are considered, with two different setups, involving different values of repetition rate, fluence, wavelength, spectral width and pulse duration. 


The 3 GHz linac section designed for the low energy (7–65 MeV) part of TOP (Therapy Oncological Protons) linac consists of eight modules of the structure SCDTL (Side Coupled Drift Tube Linac). The non axisymmetric cavities required a full 3D modelling. Electromagnetic calculations carried out by using MAFIA code gave the full mode spectrum, power losses, the coupling coefficients distribution and some indications for the tuning procedure. This paper reports a comparison between the results of this study and some RF measurements on the first module (7–13.4 MeV).

A new process of microstereolithography to manufacture freeform solid three-dimensional micro-components with outer dimensions in the millimetre size range is presented. The process, based on the use of a liquid crystal display as a dynamic mask generator, works with conventional industrial UV-sensitive stereolithographic materials. The main innovation of the process consists in using the optical frequency up-conversion of images from the visible to the UV range in order to overcome the opacity of LCD's in the UV domain. 400 × 400 points up-converted images have been obtained to generate solid three-dimensional objects.

We have adapted a scanning photoluminescence (SPL) apparatus, previously developed for III-V compounds analysis, for the characterization of SiC. The PL mapping is obtained by scanning the sample, fixed to an x-y stage with 1 μm minimal step, under a doubled Ar+ laser beam (244 nm) focused by a microscope objective (×52). For this excitation the spot diameter is about 4 μm. The PL signal can be either directly detected, giving integrated PL intensity, either dispersed using a monochromator, giving spectrally resolved PL (1 nm resolution). The measurements can be realized at room temperature for near band edge studies, or at low temperature (80 K) for deep defects investigation. The gettering effect of non radiative centres by the screw dislocations in 6H-SiC is evidenced using this apparatus.

This paper presents a original method for open magnetic cores modelling. It is called the distributed point source method. It is based on a spatial distribution of point sources located on the core surfaces emitting the magnetic flux, called the active surfaces. Compared to Finite Elements methods, the DSPM method requires only the meshing of these active surfaces, which considerably reduces the solving process time. In this paper, the DSPM method is applied on a magnetic cylindrical core, placed in free space.

A new approach is developed to estimate the geometrical factors, solid angle approximation and geometrical efficiency for a system with experimental arrangements using X-ray tube and secondary target as an excitation source in order to produce the nearly monoenergetic Kα radiation to excite the sample. The variation of the solid angle is studied by changing the radius and length of the collimators towards and away from the source and sample. From these values the variation of the total solid angle and geometrical efficiency is deduced and the optimum value is used for the experimental work.

In this article we illustrate important characteristics of the diffraction of cold atoms from periodic light potentials generated from coupling a light wave to dielectric nanostructures. We apply a recently developed theoretical approach to investigate the behavior of Cs atoms dropped onto a periodically modulated optical dipole potential where the period of the modulation is controlled by the periodicity of the dielectric array. These nanostructures take the form of one-dimensional line gratings or two-dimensional point gratings. We discuss several important parameters critical to the successful realisation of laboratory experiments and future atom-optical instrumentation using this new kind of atomic diffraction medium.

To transfer and expand in the optical telecommunication range the accurate 5S1/2(F = 3) – 5D5/2 (F = 5) rubidium frequency reference at 778 nm (385.285 THz), we employ a second harmonic generation (SHG) process coupled to an optical frequency comb (OFC) both based on the use of a low power and narrow linewidth laser diode operating around 1556 nm. The Rb optical frequency reference is known with an accuracy of 2.6 × 10−12 and exhibits a frequency stability of 4 × 10−13τ−1/2, with a Flicker plateau of 2 × 10−14 for τ > 200 s. With 20 mW of laser power at 1556 nm, we perform a SHG process in a periodically poled lithium niobate (PPLN) crystal and we obtain 6.5 μW of harmonic radiation at 778 nm, used to phase lock the IR laser against a Rb optical frequency standard (OFS). This Rb-referenced fundamental radiation at 1556 nm is duplicated as 34 lines spaced by 10 GHz using an electro-optic phase modulator (EOM). This preliminary result is mainly limited by unexpected high optical losses in the Fabry Perot cavity, which comprises the EOM.

A new pulsed laser beam equipment dedicated to the characterization of integrated circuit is presented. Using ultra-short laser pulses is a convenient way to simulate experimentally the spatial environment of integrated circuits when interactions with heavy ions occur. This experimental set-up can be considered as a complementary tool for particle accelerators to evaluate the hardness assurance of integrated circuits for space applications. These particles generate temporally electrical disturbance called Single Event Effect (SEE). The theoretical approach of an equivalence between heavy ions and a laser pulses is discussed. The experimental set-up and some relevant operational methodologies are presented. Experimental results demonstrate that the induced electrical responses due to an heavy ion or a laser pulse are quite similar. Some sensitivity mappings of integrated circuits provided by this test bench illustrate the capabilities and the limitations of this laser-based technique. Contrary to the particle accelerators, it provides useful information concerning the spatial and temporal dependences of SEE mechanisms.

An analytical method based on a fractal geometry concept was developed through the relationship between structure-texture of solid-like crackers, flat bread and Bretzels. An universal testing machine was used to determine indentation tests. The graphs were irregularly shaped so that usual interpretation was made not possible. Nevertheless, the irregular shape, or “roughness” displays auto-similarity properties which can be interpreted in terms of apparent fractal dimension texture (DT). A trained panel able to quantify the “hardness”, “porous structure” and “crispness” descriptors carried out sensorial characterisation of products. High correlation between sensorial hardness and resistance to indentation, on one hand, and between crispness and DT on the other hand was found. Modelling mathematics methods for complex systems allow useful contribution to Food Science.