Compound metasurfaces for wide-angle achromatic wavefront shaping

Metasurfaces (MSs) have attracted growing interest across both scientific and industrial sectors due to their unprecedented ability to manipulate wavefronts using arrays of subwavelength artificial structures. By harnessing the linear and nonlinear optical properties of meta-atoms, MSs offer a versatile foundation for next-generation flat-optics devices, rivaling the performance of traditional bulk components [1]. Recent advances in MS design and fabrication have significantly expanded their range of applications -particularly in near-eye displays, where they offer the potential to replace bulky conventional optics and introduce novel functionalities.

Optical see-through head-up (HUD) and head-mounted (HMD) displays have emerged as pivotal devices for augmented reality (AR) and virtual reality (VR) applications, garnering significant attention from leading industrial players. With their ultra-thin form factor, subwavelength modulation capabilities, and modulation flexibility, MSs represent a groundbreaking solution to overcome the fundamental limitations of conventional AR/VR near-eye displays. By replacing bulky optical components and enabling novel functionalities, MSs are paving the way for next-generation AR/VR technologies [2-4].

Nonlocal MSs represent a cutting-edge class of optical devices that engineer optical spectra by exploiting modes supported by arrays of adjacent, identical meta-units. These systems leverage interactions between neighboring meta-units to achieve multifunctionality, including high-quality factor resonances, essential for applications requiring narrowband spectral features. To further advance the capabilities of MSs, research efforts are increasingly focused on multilayered nonlocal MSs [5]. When layers are positioned in close proximity, nonlocal coupling effects give rise to novel collective phenomena and volumetric resonances, which must be carefully engineered. By integrating distinct nonlocal resonances within a single, compact system, these MSs enable multi-wavelength, narrowband, and spatially tailored functionalities in ultra-thin devices.

This PhD project aims to develop compound achromatic MSs to enable wide-angle, full-color imaging in waveguide-based Extended Reality (ER) displays, while addressing the vergence-accommodation conflict (VAC).

Key Objectives:

• Design and simulate multilayered achromatic MSs using FDTD/RCWA, focusing on VAC mitigation and light engine integration.
• Fabricate prototypes using EBL/NIL at CNRS cleanrooms.
• Characterize optical performance.
• Integrate MSs into waveguide-based ER systems with eye-tracking solutions and validate 3D depth perception.

Applications include:

• Lightweight, compact ER headsets with extended field of view (FoV) and 3D depth perception.
• Automotive HUDs for enhanced safety and user experience.
• Advanced imaging systems with improved optical performance.

References:

[1] A. I. Kuznetsov, et al., “Roadmap for Optical Metasurfaces,” ACS Photonics 11 (2024) 816

[2] Z. Tian, et al., “An achromatic metasurface waveguide for augmented reality displays,” Light Sci Appl 14 (2025) 94

[3] S. Moon, et al., “Single-layer waveguide displays using achromatic metagratings for full-colour augmented reality,” Nat. Nanotechnol. 20 (2025) 747–754

[4] O. Shramkova, et al., “Design of a full color single-plate waveguide combiner with high FOV,” Proc. SPIE 13414 (2025) 134140K

[5] K. Du, et al., "Optical metasurfaces towards multifunctionality and tunability," Nanophotonics 11 (2022) 1761

Université de Strasbourg is a world-renowned public research university in France, recognized for its excellence in interdisciplinary research and innovation. 

The iCube Laboratory (UMR 7357), a joint research unit of CNRS and Université de Strasbourg, is a leading center for research in computer science, electronics, photonics, and biomedical engineering. iCube brings together multidisciplinary expertise and state-of-the-art facilities to address scientific and technological challenges.

Within iCube, the D-ESSP Department (Solid-State Electronics, Systems, and Photonics) specializes in advanced electronic devices, integrated systems, and photonic technologies. The department is equipped with modern cleanroom facilities, characterization tools, and simulation platforms, enabling high-impact research in both fundamental and applied sciences.

The IPP Team (Integrated Photonics and Photonics Systems) focuses on the design, fabrication, and characterization of photonic integrated circuits (PICs), nanophotonic structures, and optoelectronic devices. The team’s research spans applications in telecommunications, sensing, and quantum technologies, with a strong emphasis on innovation and collaboration.

iCube and the IPP team are committed to training the next generation of researchers, offering PhD students a supportive environment with opportunities for publications, patents, and participation in international conferences. The laboratory’s strong industrial and academic partnerships further enhance career prospects in both academia and industry.

We are seeking a highly motivated PhD candidate with a background in:

• Nano-engineering, physics, materials science, electrical engineering, or related fields.
• Interest in nanofabrication and flat optics applications, from both design and characterization perspectives.

The candidate should:

• Be a team player with strong communication skills.
• Have a good command of English (both written and oral).
• Be prepared to present results regularly at conferences and in publications.