Extra energy coupling through subwavelength hole arrays via stochastic resonance

Interaction between metal surface waves and periodic geometry of subwavelength structures is at the core of the recent but crucial renewal of interest in plasmonics. One of the most intriguing points is the observation of abnormal strong transmission through these periodic structures, which can exceed by orders of magnitude the classical transmission given by the filling factor of the plate. The actual paradigm is that this abnormal transmission arises from the periodicity, and then that such high transmission should disappear in random geometries. Here, we show that extra energy can be coupled through the subwavelength structure by adding a controlled quantity of noise to the position of the apertures. This result can be modelled in the statistical framework of stochastic resonance. The evolution of the coupled energy with respect to noise gives access to the extra energy coupled at the surface of the subwavelength array.Comment: 12 page

Experimental evidence of percolation phase transition in surface plasmons generation

Carrying digital information in traditional copper wires is becoming a major issue in electronic circuits. Optical connections such as fiber optics offers unprecedented transfer capacity, but the mismatch between the optical wavelength and the transistors size drastically reduces the coupling efficiency. By merging the abilities of photonics and electronics, surface plasmon photonics, or 'plasmonics' exhibits strong potential. Here, we propose an original approach to fully understand the nature of surface electrons in plasmonic systems, by experimentally demonstrating that surface plasmons can be modeled as a phase of surface waves. First and second order phase transitions, associated with percolation transitions, have been experimentally observed in the building process of surface plasmons in lattice of subwavelength apertures. Percolation theory provides a unified framework for surface plasmons description

InferenceMAP: Mapping of Single-Molecule Dynamics with Bayesian Inference

Single-particle tracking (SPT) grants unprecedented insight into cellular function at the molecular scale [1]. Throughout the cell, the movement of single-molecules is generally heterogeneous and complex. Hence, there is an imperative to understand the multi-scale nature of single-molecule dynamics in biological systems. We have previously shown that with high-density SPT, spatial maps of the parameters that dictate molecule motion can be generated to intricately describe cellular environments [2,3,4]. To date, however, there exist no publically available tools that reconcile trajectory data to generate the aforementioned maps. We address this void in the SPT community with InferenceMAP: an interactive software package that uses a powerful Bayesian method to map the dynamic cellular space experienced by individual biomolecules.Comment: 56 page

Sinuosities in vascular structures

International audienceIn most organs, depending on the scale, the nature of the heart pump, the geometry and topology of the organ, some of the blood vessels tend to exhibit sinuous trajectories. We describe a part of this sinuous behavior, including partial biological and strong physical effects in a global physical framework. We will voluntarily focus on physical and topological effects. This study is performed on the vitelline membrane of the chicken embryo. Crossing angles, sinuosity, and the oscillation amplitude of the vascular system are analyzed. Surprisingly, the equation of river meandering dynamics is found to model the sinuosities in the vascular system, and an extension of this equation to non planar case is able to explain the effect of tissue global curvature on the vascular system. Results of this study could lead to a new understanding of the interplay between biological signaling and physical effects in determining the vascular pattern in different tissues

Terahertz achromatic quarter-wave plate

International audiencePhase retardera usually present a strong frequency dependence. We discuss the design and characterization of a terahertz achromatic quarter-wave plate. This wave plate is made from six birefringent quartz plates precisely designed and stacked together. Phase retardation has been measured over the whole terahertz range by terahertz polarimetry. This achromatic wave plate demonstrates a huge frequency bandwidth (?max/?min ˜ 7), and therefore can be applied to terahertz time domain spectroscopy and polarimetry. Cop. 2006 Optical Society of America

True near field versus contrast near field imaging.

International audienceWe demonstrate that in near field imaging, interaction between light and sample can be divided into two main areas: the true near field and the contrast near field domain. We performed extensive numerical simulations in order to identify the limits of these areas, and to investigate contrast near field imaging in which much easier propagation calculation can be achieved. Finally, we show an application with terahertz axonal imaging. © 2006 Optical Society of Americ

True near field versus contrast near field imaging. II. imaging with a probe

International audienceIn this letter, we extend the results previously found in near field imaging with aperture [Opt. Express 14, 11566 (2006)], where we demonstrated that interaction between light and sample can be divided into two main areas: the true near field and the contrast near field domain. Here, we show that in near field with a probe, the same division of space exists, and thus we show that a much simpler way to model theses experiments can be given. Cop. 2007 Optical Society of America

Sound Hunting: The Tape Recorder and the Sonic Practices of Sound Recording Hobbyists in France and Britain, 1948-1978

This thesis studies the history of the practice of sound recording as a hobby, in France and Britain. Only a few scholars have hitherto explored this domain, with studies of sound hunting in the Netherlands, Japan, United States. This thesis adds France and Britain to scholarly knowledge and follows sound recording hobbyists in their clubs, radio programmes, specialised magazines, national and international contests, and via their oral histories. It investigates the sound technologies used by amateurs – most notably the tape recorders; the social ties they developed; how a knowledge about sound recording and listening was formed and passed on; and the aesthetics that these so-called sound hunters developed in their works. The main focus is the rise of sound hobbyist practices around the tape recorder, between 1948 and 1978, but the work begins with an investigation of what sound hobbyists practices were with previous technologies used to record sound. Through documented examples, I show that sound recording as a hobby was practiced since the advent of sound recording technologies in the nineteenth century. However, the practice did not develop on a large scale until the tape recorder, and I show that this was due to a convergence of factors. The second chapter traces the technological factors, focusing on the affordances of sound recorders, from cylinder phonographs to tape recorders. The third chapter investigates the social factors through the ties that developed around the tape recorder. The fourth chapter provides an analytical view on how the audile culture of sound hunting developed and was passed on. The fifth chapter examines the recordings and works produced by these sound hobbyists, their influences and relationships with radio, musique concrète, experimental music, and acoustic ecology. Through these chapters, I document the advent of a new sonic sensitivity, the diffusion of new listening practices. Nowadays, there is a vivid practice of field recording undertaken by both professionals and amateurs. This thesis shows that the rise of professional sound recording was paralleled by the rise of a culture of private recording and private experimentation, with similar ideas developed independently. It also shows that the sound recording field was undergoing its structuration, normalisation, and professionalization until the 1960s, and that amateurs were part of these processes. The categories of amateur and professional were porous within that context, with amateurs and professionals co-creating disciplinarity. The thesis makes a new contribution to understanding an audile culture in Britain and France, using approaches derived from the history of technology, the social history of the media, and cultural history of the senses