Dielectric metasurfaces require the integration of large index contrast materials with accurate control over position and size for high optical efficiency. Their fabrication usually relies on well-established lithographic techniques. While lithography bears considerable advantages in terms of reproducibility and accuracy, it remains a time and cost intensive process that remains restricted in terms of materials, and difficult to scale up to large-area and non-rigid substrates. Chalcogenide glasses constitute a class of materials particularly suited for metasurfaces, thanks to their low intrinsic losses coupled with their tunable high refractive indices. The challenges associated with the nanostructuring of glassy materials has however limited their use in nanophotonics. Here, we rely on the glass characteristic viscous properties and destabilizing Van der Waals interactions, to show the rearrangement of thin chalcogenide films into well-ordered and defect free structures at the nanoscale. In particular, we show the fabrication of arrays of a variety of chalcogenides nano-objects, both continuous and isolated, with a variety of sizes and structures, and on different, rigid, flexible and stretchable substrates. Such controlled large area arrays are shown to have strong field enhancement leading to Fano resonances, which finds applications as biosensor and second harmonic generation.
Stretchable optical and electronic fibers constitute increasingly important building blocks for a myriad of applications, particularly in robotics, soft prosthesis, surgical tools and implants, and smart medical textiles. The integration of multimaterial architectures and complex functionalities within soft fibers has however for a long time remained difficult to achieve, limiting the performance and functionalities of medical fibers and textiles. In this contribution, we will show how the thermal drawing process used to fabricate optical fibers, and traditionally associated with rigid glasses or thermoplastic, can be applied to a certain class of thermoplastic elastomers. We will demonstrate that optical polymers, liquid metals, and conductive polymer composites could be co-drawn with prescribed architectures within a thermoplastic elastomer cladding. This allowed us to successfully fabricate super-elastic fibers with complex optical as well as electronic functionalities relevant for a myriad of applications in health-care. We will show in particular how such fibers can be used as precise and robust pressure, strain or more generally deformation sensors that can be seamlessly integrated within surgical tools, prosthesis, fabrics or robots. We will also discuss their potential as advanced optical probes, regenerative scaffolds or stimulating implants. This work opens novel opportunities for sensing and monitoring, scaffolds and implants, medical robotics and personalized care.
The recent ability to integrate materials with different optical and optoelectronic properties in prescribed architectures within flexible fibers is enabling novel opportunities for advanced optical probes, functional surfaces and smart textiles. In particular, the thermal drawing process has known a series of breakthroughs in recent years that have expanded the range of materials and architectures that can be engineered within uniform fibers. Of particular interest in this presentation will be optoelectronic fibers that integrate semiconductors electrically addressed by conducting materials. These long, thin and flexible fibers can intercept optical radiation, localize and inform on a beam direction, detect its wavelength and even harness its energy. They hence constitute ideal candidates for applications such as remote and distributed sensing, large-area optical-detection arrays, energy harvesting and storage, innovative health care solutions, and functional fabrics. To improve performance and device complexity, tremendous progresses have been made in terms of the integrated semiconductor architectures, evolving from large fiber solid-core, to sub-hundred nanometer thin-films, nano-filaments and even nanospheres. To bridge the gap between the optoelectronic fiber concept and practical applications however, we still need to improve device performance and integration. In this presentation we will describe the materials and processing approaches to realize optoelectronic fibers, as well as give a few examples of demonstrated systems for imaging as well as light and chemical sensing. We will then discuss paths towards practical applications focusing on two main points: fiber connectivity, and improving the semiconductor microstructure by developing scalable approaches to make fiber-integrated single-crystal nanowire based devices.