Sub-THz programmable electromagnetic surfaces based on phase change material switches
Spatiotemporal manipulation of the near- and far-electromagnetic (EM)-field distribution and its interaction with matter in the THz spectrum (0.1-0.6 THz) is of prime importance in the development of future communication, spectroscopy, imaging, holography, and sensing systems. Reconfigurable Intelligent (Meta)Surface (RIS) is a cutting-edge hybrid analogue/digital architecture capable of shaping and controlling the THz waves at the subwavelength scale. To democratize the RIS technology, it will be crucial to reduce its energy consumption by two orders of magnitude. However, the state-of-the-art does not address the integration, scalability, wideband and high-efficiency requirements.
Based on our recent research results, the main objective of this project will be to demonstrate novel silicon-based RIS architectures s at 140 GHz and 300 GHz. The enhancement of the THz RIS performance will derive from a careful choice of the silicon technology and, from novel wideband meta-atom designs (also called unit cell or element) with integrated switches based on PCM (phase change material). The possibility of dynamically controlling the amplitude of the transmission coefficients of the meta-atoms, besides their phase, will be also investigated. Near-field illumination will be introduced to obtain an ultra-low profile. To the best of our knowledge, this constitutes a new approach for the design of high-gain antennas in the sub-THz range.
Defense of scene analysis models against adversarial attacks
In many applications, scene analysis modules such as object detection and recognition, or pose recognition, are required. Deep neural networks are nowadays among the most efficient models to perform a large number of vision tasks, sometimes simultaneously in case of multitask learning. However, it has been shown that they are vulnerable to adversarial attacks: Indeed, it is possible to add to the input data some perturbations imperceptible by the human eye which undermine the results during the inference made by the neural network. However, a guarantee of reliable results is essential for applications such as autonomous vehicles or person search for video surveillance, where security is critical. Different types of adversarial attacks and defenses have been proposed, most often for the classification problem (of images, in particular). Some works have addressed the attack of embedding optimized by metric learning, especially used for open-set tasks such as object re-identification, facial recognition or image retrieval by content. The types of attacks have multiplied: some universal, other optimized on a particular instance. The proposed defenses must deal with new threats without sacrificing too much of the initial performance of the model. Protecting input data from adversarial attacks is essential for decision systems where security vulnerabilities are critical. One way to protect this data is to develop defenses against these attacks. Therefore, the objective will be to study and propose different attacks and defenses applicable to scene analysis modules, especially those for object detection and object instance search in images.
RF Circuit Design for Zero Energy Communication
Our ambition for 6G communication is to drastically reduce the Energy in IoT. For that purpose we aim at developing an integrated circuit enabling zero Energy communication.
The objective of this PhD is to design this circuit in FD-SOI and operating in the 2.4 GHz. In this PhD, we propose to use a new design technique which is currently revolutionizing the radio-frequency design. We expect that many innovations can be carried out during this PhD by combining those two innovations.
The candidate will integrate a large design team and he will participate in collaborative project at european level. As a first step, he will analyze the system constraints to choose the best architecture and derive the specifications. Then, he will formalize mathematically the performances of the backscattering technique in order to setup a design methodology. Then he will be working full time on circuit design, sending to fabrication two circuits in 22 um technology. He will be also involve in the test of the circuit as well as in the preparation of a demonstrator of the backscattering techniques. We expect to publish several papers in high level conferences.
Study of 3D pattern etch mechanisms into inorganic layers for optoelectronic applications
Optoelectronic devices such as CMOS Image Sensors (CIS) require the realization of 3D structures, convex microlenses, in order to focus photons towards the photodiodes defining the pixels. These optical elements are mandatory for the device efficiency. Their shape and dimension are critical for device performances. In the same way, devices based on diffractive optic and hyperspectral sensors are looking for complex multi-height structures. Finally, recent micro-display technologies for augmented reality (AR) and virtual reality (VR) require 3D structures difficult to achieve with conventional micro-fabrication technics.
Leti is at the state of the art on an alternative photolithography technics, so-called Grayscale. This process can produce a whole range of 3D structures not available with standard photolithography, such as concave, elliptic, pyramids and asymmetrical shapes. These structures could be used in a large number of application fields, like photonics and micro-displays (AR/VR). Once these structures achieved in photoresist, it is necessary to transfer them in an adapted functional layer using plasma etching. The etch mechanisms behind the transfer of micrometric 3D patterns into a polymer layer have been recently studied at Leti. To address new application needs, it is interesting to transfer these structures into silicon based inorganic layers because of their optical properties. Furthermore, the 3D pattern dimensions, currently few micrometers, need to be sub-micrometric for the most advanced technologies. In these condition, pattern transfer fidelity of 3D structures is even more challenging and it underlines why the etch mechanisms need to be well understood.
Currently the transfer into inorganic layers by plasma etching of submicronic 3D patterns obtained with Grayscale photolithography is not well studied in literature. Consequently, this thematic is innovative and has a real benefit. The goal of this PhD thesis is to study and understand the etch mechanisms in order to control the shape and dimension of the transferred structures. The work will be very experimental and will be mainly performed in Leti’s 300mm cleanroom. You will have access to a last generation plasma etch tool and numerous characterization technics. This thesis is in collaboration with the photolithography department and in interaction with different teams, such as the silicon platform and application department.
Learning world models for advanced autonomous agent
World models are internal representations of the external environment that an agent can use to interact with the real world. They are essential for understanding the physics that govern real-world dynamics, making predictions, and planning long-horizon actions. World models can be used to simulate real-world interactions and enhance the interpretability and explainability of an agent's behavior within this environment, making them key components for advanced autonomous agent models.
Nevertheless, building an accurate world model remains challenging. The goal of this PhD is to develop methodology to learn world models and study their use in the context of autonomous driving, particularly for motion forecasting and developing autonomous agents for navigation.
Secure and Agile Hardware/Software Implementation of new Post-Quantum Cryptography Digital Signature Algorithms
Cryptography plays a fundamental role in securing modern communication systems by ensuring confidentiality, integrity, and authenticity. Public-key cryptography, in particular, has become indispensable for secure data exchange and authentication processes. However, the advent of quantum computing poses an existential threat to many of the traditional public-key cryptographic algorithms, such as RSA, DSA, and ECC, which rely on problems like integer factorization and discrete logarithms that quantum computers can solve efficiently. Recognizing this imminent challenge, the National Institute of Standards and Technology (NIST) initiated in 2016 a global effort to develop and standardize Post-Quantum Cryptography (PQC). After three rigorous rounds of evaluation, NIST announced its first set of standardized algorithms in 2022. While these algorithms represent significant progress, NIST has expressed an explicit need for additional digital signature schemes that leverage alternative security assumptions, emphasizing the importance of schemes that offer shorter signatures and faster verification times to enhance practical applicability in resource-constrained environments. Building on this foundation, NIST opened a new competition to identify additional general-purpose signature schemes. The second-round candidates, announced in October 2024, reflect a diverse array of cryptographic families.
This research focuses on the critical intersection of post-quantum digital signature algorithms and hardware implementations. As the cryptographic community moves toward adoption, the challenge lies not only in selecting robust algorithms but also in deploying them efficiently in real-world systems. Hardware implementations, in particular, must address stringent requirements for performance, power consumption, and security, while also providing the flexibility to adapt to multiple algorithms—both those standardized and those still under evaluation. Such agility is essential to future-proof systems against the uncertainty inherent in cryptographic transitions. The primary objective of this PhD research is to design and develop hardware-agile implementations for post-quantum digital signature algorithms. The focus will be on supporting multiple algorithms within a unified hardware framework, enabling seamless adaptability to the diverse needs of evolving cryptographic standards. This involves an in-depth study of the leading candidates from NIST’s fourth-round competition, as well as those already standardized, to understand their unique computational requirements and security properties. Special attention will be given to designing modular architectures that can support different signatures, ensuring versatility and extensibility. The proposed research will also explore optimizations for resource efficiency, balancing trade-offs between performance, power consumption, and area utilization. Additionally, resilience against physical attacks (side-channel attacks and fault injection attacks) will be a key consideration in the design process. This PhD project will be conducted within the PEPR PQ-TLS project in collaboration with the TIMA laboratory (Grenoble), the Agence nationale de la sécurité des systèmes d’information (ANSSI) and INRIA.
Distributed Passive Radar
Our objective is to detect and locate drones entering an urban area to be protected by observing the signals emitted by cellular stations. Studies have shown that it is possible to locate a drone if it is close to the listening system and the cellular station (i.e. the base station). When the situation is more complex (i.e. there is no direct path between the cellular station and the radar or in the presence of several transmitting cellular stations causing a high level of interference), a single listening system called passive radar cannot correctly detect and locate the drone. To overcome these difficult conditions, we wish to distribute or deploy in the area to be protected a set of low-complexity passive radars which optimally exploit the signals emitted by these cellular stations. A distribution and deployment strategy for passive radars must then be considered by taking into account the positions of the transmitting cellular stations. The possibility of exchanging information between passive radars must also be considered in order to better manage interference linked to cellular stations.
Software support for sparse computation
The performance of computers has become limited by data movement in the fields of AI, HPC and embedded computing. Hardware accelerators do exist to handle data movement in an energy-efficient way, but there is no programming language that allows them to be implemented in the code supporting the calculations.
It's up to the programmer to explicitly configure DMAs and use function calls for data transfers and do program analysis to identify memory bottleneck
In addition, compilers were designed in the 80s, when memories worked at the same frequency as computing cores.
The aim of this thesis will be to integrate into a compiler the ability to perform optimizations based on data transfers.
EM Signature Modeling in Multi-path Scenario for Object Recognition and Semantic Radio SLAM
Context:
The vision for future communication networks includes providing highly accurate positioning and localization in both indoor and outdoor environments, alongside communication services (JCAS). With the widespread adoption of radar technologies, the concept of Simultaneous Localization and Mapping (SLAM) has recently been adapted for radiofrequency applications. Initial proof-of-concept demonstrations have been conducted in indoor environments, producing 2D maps based on mmWave/THz monostatic backscattered signals. These measurements enable the development of complex state models that detail the precise location, size, and orientation of target objects, as well as their electromagnetic properties and material composition.
Beyond simply reproducing maps, incorporating object recognition and positioning within the environment adds a semantic layer to these applications. While semantic SLAM has been explored with video-based technologies, its application to radiofrequency is still an emerging area of research. This approach requires precise electromagnetic models of object signatures and their interactions with the surrounding environment. Recent studies have developed iterative physical optics and equivalent current-based models to simulate the free-space multistatic signature of nearby objects.
PhD Thesis:
The objective of this thesis is to study and model object backscattering in a multi-path scenario for precise imaging and object recognition (including material properties). The work will involve developing a mathematical model for the backscattering of sensed objects in the environment, applying it to 3D SLAM, and achieving object recognition/classification. The model should capture both near- and far-field effects while accounting for the impact of the antenna on the overall radio channel. The study will support the joint design of antenna systems and the associated processing techniques (e.g., filtering and imaging) required for the application.
The PhD student will be hosted in the Antenna and Propagation Laboratory at CEA LETI in Grenoble, France. The research will be conducted in partnership with the University of Bologna.
Application:
The position is open to outstanding students with a Master of Science degree, “école d’ingénieur” diploma, or equivalent. The student should have a specialization in telecommunications, microwaves, and/or signal processing. The application must include a CV, cover letter, and academic transcripts for the last two years of study.
Advanced RF circuit design in a system and technology co-optimization approach
This thesis addresses the two major challenges facing Europe today in terms of integrating the communication systems of the future. The aim is to design RF integrated circuits using 22nm FDSOI technology in the frequency bands dedicated to 6G, which will not only increase data rates but also reduce the carbon footprint of telecoms networks. At the same time, it is essential to consider the evolution of silicon technologies that could improve the energy efficiency and effectiveness of these circuits. This work will be carried out with an eye to the design methodology of radio frequency systems.
Within the framework of the thesis, the objective will be broken down into three phases. Firstly, simulation tools will be developed to predict the performance of Leti's future 10nm FDSOI technology. The second stage will involve identifying the most relevant architectures available in the literature for the application areas envisaged for the technology. A link with upstream telecoms projects will be systematically established to ensure that the candidate understands the systems' challenges.
Finally, in order to validate the concepts developed, the design of an LNA and a VCO as part of an ongoing project in the laboratory will be proposed.
The candidate will join a large team that works on new communication systems and addresses aspects of architectural study, modeling and design of integrated circuits. The candidate must have serious skills in the design of integrated circuits and radio frequency systems as well as good ability to work in a team.