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In this paper we report results on a field-effect induced light modulation at λ = 1.55 um in a high-index-contrast waveguide based on a multisilicon-on-insulator (MSOI) platform. The device is realized with the hydrogenated amorphous silicon (α-Si:H) technology and it is suitable for monolithic integration in a CMOS Integrated Circuit. The device exploits the free carrier optical absorption electrically induced in the semiconductor core waveguide. The dynamic behaviour of the device was experimentally and theoretically analyzed in presence of a visible illumination showing a link between the photogeneration and the free carriers provided by doped α-Si:H layers. The core waveguide contains several thin dielectric films of amorphous silicon carbonitride (α-SiCN) embedded along its thickness highly enhancing the absorbing action of the modulator held in the on-state.

Low-loss hydrogenated amorphous silicon (α-Si:H) waveguides were realized by plasma enhanced chemical vapour deposition (PECVD) on a transparent conductive oxide (TCO) layer which is intended to provide the buried contact for the application of an external bias in active devices, e.g. switches and modulators. In particular we propose a technological solution to overcome both the strong reduction in optical transmittance due to the very high extinction coefficient of metal contacts and, at the same time, the optical scattering induced by the texturization effect induced in α-Si:H films grown on TCO. The very high optical propagation losses were minimized by depositing a spin-on-glass (SOG) layer between the α-Si:H core-layer and the TCO bottom contact. In this case, propagation losses of 2.5 dB/cm at 1550 nm were measured. All the fabricated samples were optically characterized and the surface roughness was accurately measured using a mechanical profilometer. We observed that, for an α-Si:H core-layer directly deposited on the TCO contact, the surface roughness is of the order of 100 nm leading to totally opaque waveguides. The experimental performances have been compared to those obtained through calculations using an optical simulation package. The results are found to be in agreement with the experimental data.

In this paper the photometric or the so called "shape from shading" method is presented. In comparison to existing methods the efficiency of the detector system was considered and the requirements of the cosine Lambert's law for the angle distribution of the emitted electrons are suppressed. This new method was experimentally verified by measuring a steel sphere, a holographic grating and a hologram.

We propose the use of a new diffractive optical element coined Devil's Vortex-Lens (DVL) to produce optical tweezers. In its more general form it results as the combination of a Devil’s lens and a helical vortex phase mask. It is shown that under monochromatic illumination a DVL generates a focal volume with several concatenated doughnut modes that are axially distributed according to the self-similarity of the lens. The orbital angular momentum associated to each link in the chain is investigated.

Photopolymer media that uses holographic data storage generally causes volume shrinkage. This volume shrinkage distorts the recorded interference fringes. We propose an adaptive optics using novel index to compensate this distortion. The SNR value is improved from 2.1 dB to 3.4 dB in the worst part of a reproduced image and the peak intensity and the full width of the half maximum of an angle are improved by 6% and 10%, respectively. These results prove that adaptive optics using this novel index worked effectively.

We propose a simple measurement setup in reflection and a movement evaluation procedure based on a two dimensional recording of subjective speckle images. Averaging of cross correlation functions is used to determine translations. We show experimentally a 10 nm precision on a 50 µm measurement range with respect to systematical errors. An image library is shown to extend the range of measurements. Limitations are given and documented improvements are predicted to result in accuracy better than 5 nm over a range of 150 µm.

Today, the controls by reflection of optical coatings are most of the time made with flat samples thanks to commercial spectrophotometers. However, components become smaller and more complex, curvature radius of lenses or mirrors are larger, so that measures are not so accurate and sometimes are not possible. Flat samples don’t represent anymore the real reflection ability of the component. So to perform this kind of measurements, special devices are needed. A new means developed by the French Atomic Energy Commission (CEA) is proposed to fill in this gap. This device has a accuracy of 0.06% on flat sample over the 400 nm to 950 nm wavelength range with a spot size of 100 mm. It can measure the reflectance of samples even if their shapes are spherical. We investigate stainless steel balls and optical micro components (mirrors and lens) thanks to the tiny size of the analyzing spot of our reflectometer. Herein we introduce our first results on small optical components and show the limiting factors of our device.

When moulds are illuminated by visible electromagnetic-EM radiations, several effects on nucleus materials and nucleotides can be detected. These effects have a significant influence on mould generation or destruction. This paper presents the effects and implications of a red diode laser beam (660 nm), a second-harmonics of a Nd:YAG laser emitting green beam (532 nm), or the combination of both, on the eradication of Pistachio mould fungus. Incident doses (ID) of both beams are kept identical throughout the experiment. The absorption spectrums of irradiated mouldy samples and the bright-greenish-yellow-fluorescence (BGYF) of fungus occurring in mould texture due to electronic excitation are investigated. We found that a combination of a green and a red laser beam with an ID of 0.5 J/cm^2 provides the optimal effects on Pistachio mould fungus eradication.

In this paper we investigate the effects of visible to near infrared (NIR) laser illumination on the optical transmission (OT) and morphological changes (MC) of thin, curved surfaces of polycarbonate (PC) as employed by industry. The second harmonic of Nd:YAG laser (532 nm) and two diode lasers (665 and 980 nm) were used as sources. We have shown that the morphological changes and optical transmission of the PC elements are influenced by visible to infrared coherent illumination. The morphological changes of the PC surfaces are determined using atomic force microscopy (AFM), demonstrating the appreciable changes caused by the shorter wavelengths (higher energy). When analyzing the OT spectra of PC thin films, a measurable decrease in the OT of the PC surfaces which were illuminated by 532, 665 and 980 nm, in particular 532 nm, for energy densities greater than 25 J/cm^2 can be seen.

Lasers represent a well consolidated technology: nevertheless, research in this field remains very active and productive, in both basic and applied directions. At the moment significant attention is given to those sources that bring together high power and compactness. Such high power lasers find important applications for material treatments and such applications are presented by Ehsani et al and Saiedeh Saghafi et al, in the treatment of dielectric thin films (Alteration of optical and morphological properties of polycarbonate illuminated by visible/IR laser beams) or of biological tissues like pistachio seeds (Investigating the effects of laser beams (532 and 660 nm) in annihilation of pistachio mould fungus using spectrophotometry analysis). In particular the latter paper show how laser sources can find very important applications in new domains, preserving goods and food without the need for preservatives or pesticides by simply sterilizing them using light. Optical Micro and Nano Systems presents a new domain for exploration. In this framework this special issue is very attractive, because it assembles papers reporting new results in three directions: new techniques for monitoring integrated micro- and nano-systems, new integrated systems and novel high performance metamaterial configurations. Integrated micro-components can be monitored and controlled using reflectance measurements as presented by Piombini et al (Toward the reflectance measurement of micro components) . Speckle formation during laser beam reflection can also be a very sophisticated tool for detecting ultra-precise displacements, as presented by Filter et al (High resolution displacement detection with speckles : accuracy limits in linear displacement speckle metrology). Three dimensional integrated optical structures is indeed a big challenge and a peculiarity of photonics, they can be formed through traditional holography or using more sophisticated and novel technologies. Thus, special manipulation of the writing-reading optical beam can push holography toward storages at higher data densities, as presented by Norihiko Ishii et al (Wavefront compensation method using novel index in holographic data storage). Along a similar direction Furlan et al describe a very innovative technique for producing optical traps using novel Devil micro-lenses (Volumetric multiple optical traps produced by Devil’s lenses). Vynnyk et al presented an interesting application of electron microscopy for monitoring sub-micrometric structures in 3D configurations (3D-measurement with the stereo scanning electron microscope on sub-micrometer structure). Finally, S. Rao et al present two interesting papers on integrated structures compatible with silicon technology: one describes the realisation of low-loss waveguides using amorphous silicon, a relatively novel material with many applications in very different domains (Low-loss amorphous silicon waveguides grown by PECVD on indium tin oxide), and one on the realisation of a electrically drivable device with affective compatibility with CMOS technology (Electro-optical modulating multistack device based on the CMOS-compatible technology of amorphous silicon). We hope that this special issue of the Journal of the European Optical Society will reflect the interest of the European Scientific Community toward these fundamental and applied topics and will demonstrate to readers some of the actual directions of research. We express our full appreciation to the authors that participated to this initiative which acts only as a primer for the vast amount of work now being undertaken in laser physics and applications in micro- and nano-systems. We would like to give a special thank to the paper reviewers for their important role in the paper selection process and all the journal staff for their very professional support, dedication and energy, which made this special issue feasible.

The anisotropy complex refractive index of tissue is an important parameter in understanding the behavior of light, including its transportation in and interaction with tissues. We used the specular reflection method to investigate the anisotropy complex refractive index of chicken tissue with fibrous structures in vitro at a wavelength of 650 nm. The measurement data were highly consistent with the Fesnell equations. The results showed that the real refractive index was higher along the orientation of the fibers than along the cross section, but the imaginary refractive index was nearly identical. Furthermore, the fiber orientation was in the direction of the optic axis of the chicken tissue and the chicken tissue section was similar to a negative uniaxial crystal wafer.

In this paper, the quantitative schlieren method is extended to measure the concentration field of an injected gaseous fuel along several planes perpendicular to the jet axis. Background Oriented Schlieren (BOS) is used as a quantitative flow field concentration measurement based on the deflection made by features in the background pattern. The flow field which is located between the camera and the background pattern varies the intensity value of the background points in the transfer medium. The Optical flow algorithm, which is used to measure the deflection vectors in the background due to the change in index of refraction, is modified to consider the change in intensity of the background image. Optical tomography served as a tool to extract the index of refraction of the gaseous field. Mole fraction values at differentplanes perpendicular to the jet axis are obtained and displayed.

Mechanical forces exerted by an emitting dipole on the interface between two media with different dielectric susceptibilities are found for different distances between the dipole and the interface. Estimations of the force are given based on known values of molecular polarizabilities for inelestic processes such as Raman scattering and fluorescence including those that occur near metal structures.

Digital in-line holography is revisited to propose a mathematical model that describes the recording-reconstruction process as a linear shift-invariant system with a pseudo-point spread function even when the images are out of the optimal plane in the sense of signal processing. A particular case is treated to show that the optimal plane is the best focus plane in the sense of optics. Next, an exact solution of the holographic reconstruction by correlation is given. By means of the previous results, we study the behavior of the result of the correlation function between the diffraction pattern function produced by an opaque disk and a chirplet function and between the diffraction pattern produced by a phase disk and the same chirplet function.

For the highly accurate topography measurement of nearly flat optical surfaces, scanning deflectometric methods are capable of achieving nanometer accuracy. In these systems, an autocollimator is typically used as the deflectometric sensor and a pentaprism is applied for the scanning process. When ultimate accuracy is desired, a drawback of these systems is that the autocollimator output signal often depends slightly on the optical path length, resulting in topography errors during scanning. Here, we present a new deflectometric method which separates the angle measurement from the scanning process and, thereby, avoids possible errors due to different optical path lengths. In contrast to conventional deflectometry, the new technique achieves an almost exact autocollimation by appropriately tilting the specimen during scanning. The tilt angle necessary to achieve autocollimation complies with the deflectometric angle determined in conventional deflectometry. The tilt angle is measured with an additional autocollimator at a fixed distance without errors due to different optical path lengths. The separation of angle measurement and the scanning process enable both tasks to be optimized independently. This opens up new possibilities of reducing lateral resolution by facilitating smaller apertures and of assessing topographies with larger curvatures. The concept was tested successfully by a demonstrator setup. The first measurements on a test specimen agree with results obtained with the established Extended Shear Angle Difference (ESAD) technique at the one nanometer level.

When coupled modes are excited in a multilayered structure, the profile of the reflected beam presents exotic characteristics like unexpectedly large lateral shifts or beam enlargment. These results are surprising because they are not accounted for by classical approaches (Artmann's formula or Tamir's description of the reflected beam's profile). Studying such situations requires reliable numerical tools - that is why our programmes are published with this paper. Such tools can be used to understand the behaviour of any multi-layered structure.