Structures that strongly confine the photons on the scale of the light wavelength have been studied in semiconductor physics for about 20 years, giving rise to a wealth of fundamental studies exploiting the reinforced light-matter (both linear and nonlinear) interaction. Most studies were done in well mastered III-V material systems, which however suffer from some drawbacks such as a low exciton binding energy, low barrier potentials in heterostructures and a transparency window limited to the near infrared. Semiconductors of the III-N family have quite peculiar properties such as a large excitonic binding energy and a transparency window that extends to 200 nm. They are the dominant material family for the fabrication of UV-blue-green optoelectronic devices (laser diodes and light-emitting diodes) as well as for white light production. Nitrides are already massively used for high density optical storage and display light sources but shorter wavelength optoelectronic devices are also potentially very interesting for biochemical sensors, purification, disinfection and medical diagnosis. Interestingly, a current trend consists in integrating III-N materials on silicon. For these reasons, III-N materials are thus expected to play a significant role in novel photonic systems and, in this respect they are very good candidates to probe light-matter interaction in photon confining structures. It is however notorious that III-N semiconductors are difficult to process and this technological drawback has hindered achievements in highly confined optical structures. It is the aim of the QUANONIC project to probe quantum optical and nonlinear effects in AlGaN based high optical quality microdisks and photonic crystal (PC) structures. Based on the know-how of the consortium to fabricate and to probe III-N based microcavities, several goals will be pursued and if successful will represent major breakthroughs for the development of novel optoelectronic devices integrated on silicon. Goal 1 : Microlaser and strong coupling at UV wavelengths in III-N microcavities. Fabrication of optical resonators having high quality factors is now mastered by the consortium. The next issue to address to reach lasing is the optimization of the active region in order to get high gain active medium: our strategy is twofold. i) We will seek to grow GaN/AlN quantum dots (QD) with high oscillator strength and high areal density. A detailed study of microlasing and Purcell effect will be made. ii) By exploiting the large oscillator strength of III-N excitons, high quality factor microcavities will be designed for photon-exciton strong coupling. We shall explore the conditions for strong coupling, both for confined modes and for extended modes in III-N photonic crystals. The ultimate goal will be to reach polariton lasing. Goal 2 : Frequency conversion in III-N photon confining structures for deep UV sources. Thanks to a much wider transparency window than conventional semiconductors and to large nonlinear coefficients, III-N are very good candidates for frequency conversion in confined structures. The photonic crystal geometry allows for large field intensities (cavity enhanced frequency conversion) and also for the tailoring of the refractive properties. Original phase-matching conditions will be demonstrated experimentally, such as backward second harmonic generation (SHG) and “all angle” SHG that are very difficult or impossible to obtain in larger scale periodically poled nonlinear materials. As a final and ambitious objective of the project, we propose an investigation of a compact coupling of semiconductor lasers and frequency converting cavities that enlightens the potentialities of our approach for forthcoming UV optoelectronics. The integration of nitride laser emission and frequency doubling in a III-N photonic structure represents a realistic opportunity to demonstrate an all-semiconductor compact optical source operating in the 200-250 nm wavelength range.

This project aims to develop frequency tunable quantum cascade lasers (QCL) in the mid-infrared exploiting concepts from meta-material science. The tuning will be achieved by introducing judiciously designed meta-layers, whose effective index is linked to the geometric parameters of the meta-atoms composing the structure, and/or by using dielectric materials exhibiting sharp phase transitions. The optical waveguides will be designed to increase the overlap between the optical laser mode and the artificial meta-surfaces. The effective index of the upper cladding can be controlled through the introduction of tunable dielectric materials. The result brought by this novel approach is the development of QCLs with much larger tunability ranges with respect to standard distributed-feedback QCLs. The proposed approach is also easier to implement than External Cavity QCLs. The last part of the project will target the use of these tunable sources for THz generation via difference frequency.

Fifty years of dramatic advances in microelectronics have reshaped the way we communicate and work, but progress on silicon-based technologies could well be reaching their limits. This calls for fresh research on new materials for the electronic industry. In this context, fabrication of high quality oxide heterostructures (HS) lies at the heart of the emerging field of oxide electronics. Indeed, Ohtomo and Hwang (2004) have shown that a two dimensional electron gas (2DEG) can be formed in HS based on the wide-gap band insulator SrTiO3 (STO). This is appealing, as STO is a member of the transition metal oxides (TMOs). These materials present unique properties, such as high temperature superconductivity in cuprates, colossal magnetoresistance in manganites, multiferroic behaviour in bismuth ferrites. Owing to their similar perovskite structure, one can combine them into a large variety of HS, hoping for novel emerging properties at their interfaces. A recent breakthrough due to the Coordinator and several members on this project may open a new way to create and study 2DEGs in TMOs: we found that a 2DEG can be obtained at the bare surface of insulating STO by simply fracturing a crystalline sample in vacuum. An exciting perspective, which is at the core of the present proposal, is that the underpinning mechanism of such a 2DEG may be generic to other perovskites, and that the ensuing 2DEGs might inherit some of the properties of their host compounds, which are often correlated electron systems. Thus, we will aim at the creation and engineering of novel 2D electronic states at the surface of TMOs endowed with technologically promising functionalities. Materials to be investigated include the ferroelectric BaTiO3 (BTO), as well as manganites and multiferroics, which could present strongly spin-polarized 2DEGs allowing the creation of electrically controllable spintronic devices. Furthermore, very recent results from our consortium suggest original routes to craft non-trivial topological states in oxide surfaces. In this project, we will explore the realization of new topological 2DEGs at the surface of TMOs. Moreover, in order to search for optimal or new functionalities, we will tailor in-situ their microscopic properties, like carrier density, spin-orbit or spin-spin interactions, and directly follow the evolution of their electronic structure. At the core of our strategy, we will use a combination of state-of-the-art in-situ preparation and characterization techniques and photoemission spectroscopy. Understanding such surface metallic states requires detailed studies of the role of oxygen vacancies created during the fracturing process. Key issues to be addressed include identifying the mechanisms that can form, stabilize and allow an engineering of the oxygen vacancies at the surface of TMOs. Furthermore, we will find ways to protect the surface 2DEGs to render them usable for transport measurements and for applications. This project is a re-submission of our project “LACUNES”. We have taken into account the remarks made by the Evaluation Committee, and made sure to allay their concerns. Outcomes of this project can open new avenues for the development of electronics based on TMOs. The consortium combines the necessary skills to meet the challenges of the present proposal, as our recent experimental/theoretical collaboration shows. Our discovery and recent preliminary results, described below, demonstrate the feasibility and potential of our approach to create novel 2DEGs in several TMOs.

One of the most active recent developments in computer vision has been the analysis of crowded scenes. The interest that this specific field has raised may be explained from two different perspectives. In terms of applicability, continuous surveillance of public and sensitive areas has benefited from the advancements in hardware and infrastructure, and the bottleneck moved towards the processing level, where human supervision is a laborious task which often requires experienced operators. Other circumstances involving the analysis of dense crowds are represented by large scale events (sport events, religious or social gatherings) which are characterized by very high densities (at least locally) and an increased risk of congestions. From a scientific perspective, the detection of pedestrians in different circumstances, and furthermore the interpretation of their actions involve a wide range of branches of computer vision and machine learning. Single camera analysis This represents the typical setup for a broad range of applications related to prevention and detection in public and private environments. Although some camera networks may contain thousands of units, it is quite common to perform processing tasks separately in each view. However, single view analysis is limited by the field of view of individual cameras and furthermore by the spatial layout of the scene; also, frequent occlusions in crowded scenes hamper the performance of standard detection algorithms and complexify tracking. Multiple camera analysis Multiple camera analysis has the potential to overcome problems related to occluded scenes, long trajectory tracking or coverage of wider areas. Among the main scientific challenges, these systems require mapping different views to the same coordinate system; also, solutions for the novel problems they address (detection in dense crowds, object and track association, re-identification etc.) may not be obtained simply by employing and extending previous strategies used in single camera analysis. In our study, we focus on solving the problem of analyzing the dynamics of a high-density crowd. The goal of the present proposal is to tackle the major challenge of detecting and tracking simultaneously as particles thousands of pedestrians forming a high-density crowd, and based on real data observations, to assist in proposing and validating a particle interaction model for crowd flow. Our project is original in its aim of performing particle level analysis, as well as through its emphasis on wide area multiple camera tracking. The strategy we intend to follow is based on a feedback loop involving particle segmentation and tracking, which aims to address the main difficulty of this problem, the uncertainty of data association. The value of such a study rests on the need for better solutions for human urban environments and for transport infrastructures, that not only improve the efficiency of the flows involved, but also do it in such a way as to increase and not diminish the quality of life. Another important prerogative of such research is to prevent fatalities during large scale events and gatherings. Toward the end of the project, we intend to propose a methodology for the analysis of highly-dense crowds which benefits from the recent developments in single camera tracking, and also proposes effective data association solutions among multiple cameras. Secondly, we intend to support the research community by providing a multi-camera dataset which would also allow for a stronger implication of additional fields involved in the general study of crowds, mainly physics, control, simulations and sociology.

Increasing the detection sensitivity while extending simultaneously the analysis to numerous biomarkers simultaneously (multiplexing) are essential breakthroughs to be addressed for improving significantly the field of biomedical analysis. Such progresses would allow earlier diagnostics and a better differentiation in pathologies as is currently required for numerous diseases and in particular for septic shocks and severe sepsis, opening the way to personalized treatments to the concomitant benefits of the patients and of the social care administrations. Advances in multiplexed analysis are also a crucial ask from pharmaceutical industries within the frame of their research programs on high throughput screenings. Fluoro-immunnoassays are based on the biomolecular recognition events that occur between biomarkers and specific antibodies labelled with fluorescent dyes. Upon the immune interaction, the spatial proximity can lead to resonant energy transfer processes (RET) that can be monitored to quantify the biomarkers concentrations. But if the development of monoclonal antibodies provides very specific interactions with the antigens, the current use of conventional fluorescent labels severely restricts the detection sensitivity and the possibility of multiplexed analysis on a single sample. The NanoFRET project aims at exploiting the exceptional spectroscopic properties of luminescent semiconducting nanocrystals (Quantum Dots, QDs) to provide ultrasensitive multiplexed fluoroimmunoassays. By combining CdSe based QDs with lanthanide complexes, we recently demonstrated that one can significantly increase the sensitivity of FRET associated signals, and that such analysis can be conducted on up to five different recognition events in a same sample (multiplexing). Within the NanoFRET project, we intend to enlarge the proof of concept obtained from the biotin-streptavidin interaction to immunocomplexes formed between antigens and antibodies, by addressing the nanocrystals with antibodies at their surface. In particular, we will focus our attention on the detection of procalcitonin (PCT) and proadrenomedulin (PAM), biological marker of systemic inflammatory reaction and of severe sepsis, the early detection of which would lead to the development of improved treatment and therapy. NanoFRET is based on the partnership of three public research teams, internationally recognized within the fields of luminescent semiconducting nanoparticles, lanthanide complexes for biolabelling and energy transfer phenomena, associated with a French industrial partner, specialized in clinical diagnostic and in the development of fluoroimmunoassays. It aims at bringing the exploratory results yet obtained (and protected by patents of the CNRS and the CEA) at and applied level targeted towards sepsis detection, while covering the aspects of a potential industrial development. This highly pluridisciplinary research program will allow the transfer of a fundamental technology to the industrial partner and aims at bringing significant breakthroughs within the fields of health nanotechnologies by addressing innovative nanosystems based on quantum dots.