Analog to digital converters (ADC) are essential components to enhance performance of numerous equipment and systems, for both civilian and military applications. As the sampling rate of electronic ADCs will be particularly capped by sampling signal jitter (100 fs to the state of the art), optical approaches are studied to take advantage of much lower jitter obtained using laser pulses (fs or less). This ADC Poly proposal aims to demonstrate the feasibility of an innovative solution based on the use of an optical deflector, realized by using integrated optics technology. The deflector is the central component of an all-optical ADC that, ultimately, could be capable to sample at a very high rate of 40 Giga samples per second with a resolution of 6 bits or more, which could be then one of the best performances obtained with photonic ADCs. The demonstrator aimed in this project will consist of a deflector, based on an optical leaky waveguide made of electro-optic polymers (EO), capable of addressing a coding mask with 8 resolved lines (3 bits). The leakage angle is controlled by the voltage to be digitized which is applied to the driving electrodes. Active integrated optical components based on EO polymers, modulators for example, usually operate with a microstrip electrode on the EO polymer guide, ensuring an optimal overlap integral between optical and electrical waves. In the case of the deflector, the light leaks from the top of the optical waveguide, making this topology inoperative, so the driving electrode must be located laterally, on both sides of the optical waveguide, and additionally buried, to optimize this overlap. The first challenge of the project is therefore to develop a new technological fabrication process, more complex than those commonly used and to validate the behavior of the EO structure. The buried and laterally placed poling electrodes requested by our design do not allow using the usual poling scheme for chromophores. So, a microwave filter solution is proposed to enable both DC and microwave operation of electrodes. The leaky optical field, distributed along the waveguide, must be collected and focused in the detection plane. The second challenge is then to design an appropriate superstrate over the leaky waveguide as well as micro-optical elements to collect and focus the leaky lightwave. A task is specifically dedicated to the integrated design of the whole structure, optical and microwave parts, of the deflector, as well as the micro-optical components aiming collecting the leakage beam. The fabrication task is divided into several stages. At first, passive waveguides will be made, then phase modulators with the driving electrodes at the same level as the optical waveguide. The characterization of these intermediate components allows to determine the parameters requested for the optimization of the leak waveguide design for the deflector.

The past several decades have been marked by the exponential growth of computer-generated data and related information processing. Such growth continues now, e.g. with the deployment of gigabit internet and 4G wireless networks, and will likely be accelerated by emerging technologies such as robotics, biotechnology, and distributed sensor networks. Given the inevitable end of scaling of conventional semiconductor circuits and increasing energy-use awareness, alternative ways to allow for information processing in an energy efficient fashion must be developed: Nanotechnologies open the way to new computing paradigms and circuits that could replace the actual technology based on Von Neumann architecture and CMOS devices. The aim of this project is to develop hardware systems of memristive nanodevices for neuro-inspired computing. Different promising ideas have been proposed for alternative computing solutions based on bio-inspired computing paradigm, such as perceptron, associative memory or Bayesian inference. These propositions are particularly promising for classification, recognition or anticipation tasks, which are hardly implement in conventional computers. If theoretical works are already available for estimation of performances and functionalities demonstration, experimental realization of these computing systems represent a challenge with high impact potentiality. The recent proposition of memristance by D. Strukov based on RRAM technology offers a unique opportunity to bridge the gap between theory and experiment by providing simple two terminal nanodevices that could match the requirement in terms of memory density and parallel interconnect for such circuits. I propose in this project an approach based on the development in parallel of (i) a specific technology for neuro-inspired computing - more precisely, the successful technology will implement the synaptic operation by coupling analog memory (or multistate resistance) and plasticity properties (i.e. tuning of memory volatility) – and (ii) the realization of hybrid circuits for neuro-inspired function demonstration and evaluation. These hybrid circuits will be built with hardware integrated nanodevices and Integrated Circuit breadboarding. This approach is directly compatible with hybrid CMOS/nanodevices circuit development that is envisioned for such neuro-inspired systems. If successful, such approach would allow orders of magnitude energy savings in information processing and enable more functional electronics.

Fast amplitude and phase modulation is essential for a plethora of applications in photonics, including laser amplitude/frequency stabilisation, coherent detection, optical communications, spectroscopy, gas sensing etc. In the mid-infrared (MIR) wavelength range (3-12um) broadband MDs are missing, hampering the progress of MIR photonics. In this project we aim at demonstrating two types of power efficient and broadband (up to ~40GHz bandwidth) integrated MIR amplitude- and phase-MDs, suitable for industrial production, that will be capable of addressing the needs of emerging MIR photonics applications. The frequency response of these devices (optimised in the 9.5-10.5um wavelength range) will be fully characterised using an in-house fabricated ultra-broadband (>70GHz) detector and a VNA analyser. Finally, the potential of the MDs for spectroscopy/gas sensing applications will be demonstrated by setting up an original high resolution-spectroscopy experiment.

The use of collective excitations of electron gases in metals, namely plasmonics, has proved to be a major breakthrough in the design of nano-systems in many fields, spanning from optics to biology. The huge local enhancement of the electrical field around a plasmonic object has been harvested to improve the emission yield of many light emitters or scattering cross-section of nano-objects. This has been fruitful for optical imaging (for biological labels, for instance) and has also paved the way to the design of many metamaterials and systems for transformation optics. The enhancement of the local electromagnetic field has further been harvested to improve the sensitivity of specific optical spectroscopies (such as Surface enhanced Raman Scattering). However, most of the afore-mentioned progresses have taken advantage of the plasmons in noble metal nanoparticles and more specifically those of silver and gold. The choice of these metals limits the interest of plasmonics to the visible range of electromagnetic waves. Another major challenge in plasmonics is the high loss of the metallic nanoparticles. Besides, noble metals such as gold and silver are hardly compatible with the conventional technologies of the Si industry. On the other hand, there is a major interest in expanding the spectacular properties of plasmonic nano-objects to the infra-red (IR) range. First, mid IR, corresponding to wavelengths of approximately 3 to 30 µm, is the range where most of the chemical molecules have their spectroscopic signature. Second, near IR, with wavelengths around 1.5 µm, corresponds to the telecommunication range. Thus, there is an obvious benefit to control the electromagnetic field amplitude and location at the nanoscale of these different waves: one could improve the coupling of light with molecular vibrations and telecom signal respectively and design highly sensitive optical detectors. A recent and timely issue concerns the development of nanomaterials that allow tuning the plasmon resonance through the electron gas concentration. Degenerate semiconductors are particularly suited for that purpose. Among them, Ga doped ZnO (GZO) appears a most interesting candidate. In the present project, we aim at developing GZO based nanostructures with tunable IR plasmons. If the demonstration of GZO potential for IR plasmonics has been done recently using thin films or nanoparticles, much remains to be done for systems with low dimensionality (nanowires or nanoparticles). Two main issues remain to be addressed and explained: first, what is the range over which the plasmon resonance can be tuned? In other words, what are the doping limits (both minimum and maximum) that can be sustained in nano-objects? Second, what are the factors that rule the losses? Indeed, it is observed on the one hand that not all the dopants contribute to the plasmon and on the other hand that the plasmon resonances are broader, thus more subject to losses, that what is expected. Our project aims at answering these two issues in order to design efficient tunable IR plasmonics nano-objects. This project, based on novel degenerate ZnO nanostructures, will allow the development tunable IR nano-plasmonics. For this wavelength range, there is no competitive alternative which allows tuning the plasmon resonance (through composition, size, shape…). The present project is not an incremental development of existing technologies. It rather presents a high breakthrough potential.