Titanium nitride (TiN) is a very promising new plasmonic material to replace traditional plasmonic materials like gold and silver, especially thanks to its thermal and chemical stability. However, its chemical resistance and its hardness make TiN difficult to microstructure. An alternative approach is to micro-nanostructure a titanium dioxide (TiO2) coating and then to use a nitridation reaction to obtain a micro-nanostructured TiN coating. This is an easy, rapid and cost-effective structuring process. In this paper, we demonstrate that rapid thermal nitridation (RTN) can be combined with nanoimprint lithography (NIL) to rapidly micro-nanostructure a TiN layer. This innovative approach is applied to a micro-nanostructured TiN layer for plasmonic response in the near infrared range. Experimental and theoretical approaches are compared.

Deploying advanced imaging solutions to robotic and autonomous systems by mimicking human vision requires simultaneous acquisition of multiple fields of views, named the peripheral and fovea regions. Low-resolution peripheral field provides coarse scene exploration to direct the eye to focus to a highly resolved fovea region for sharp imaging. Among 3D computer vision techniques, Light Detection and Ranging (LiDAR) is currently considered at the industrial level for robotic vision. LiDAR is an imaging technique that monitors pulses of light at optical frequencies to sense the space and to recover three-dimensional ranging information. Notwithstanding the efforts on LiDAR integration and optimization, commercially available devices have slow frame rate and low image resolution, notably limited by the performance of mechanical or slow solid-state deflection systems. Metasurfaces (MS) are versatile optical components that can distribute the optical power in desired regions of space. Here, we report on an advanced LiDAR technology that uses ultrafast low FoV deflectors cascaded with large area metasurfaces to achieve large FoV and simultaneous peripheral and central imaging zones. This technology achieves MHz frame rate for 2D imaging, and up to KHz for 3D imaging, with extremely large FoV (up to 150{\deg}deg. on both vertical and horizontal scanning axes). The use of this disruptive LiDAR technology with advanced learning algorithms offers perspectives to improve further the perception capabilities and decision-making process of autonomous vehicles and robotic systems.

It is shown that substrate pixelisation before epitaxial growth can significantly impact the emission color of semiconductor heterostructures. The wavelength emission from InxGa1−xN/GaN quantum wells can be shifted from blue to yellow simply by reducing the mesa size from 90 × 90 µm2 to 10 × 10 µm2 of the patterned silicon used as the substrate. This color shift is mainly attributed to an increase of the quantum well thickness when the mesa size decreases. The color is also affected, in a lesser extent, by the trench width between the mesas. Cathodoluminescence hyperspectral imaging is used to map the wavelength emission of the InxGa1−xN/GaN quantum wells. Whatever the mesa size is, the wavelength emission is red-shifted at the mesa edges due to a larger quantum well thickness and In composition.

Living organisms have developed many strategies to produce colors and to modify appearance. Even if the use of pigments is widely spread, the effects produced by micro/nano patterning allow a larger range of possibilities. Indeed, the structuration of materials on multiple levels combined with intrinsic material properties offer a wide range of visual effects such as: metallic effect (possible without metal layer), gonio-chromatic appearance, glossy or mat surfaces (which can lead to efficient contrast effects), or super water repealing surfaces (which can punctually and locally change the surface appearance). In this way, surface patterning can generate aesthetic mimicking the beetles which often show gold or metallic green chitin shell due to 3D photonic crystal structures. However, they can also lead to wider optical effects to mimic moth eyes, which are super effective at capturing light at night thanks to nano-cones preventing the reflection of light. These effects are very attractive since they rely only on physical and topographical properties, bringing possibilities to create colors and optical effects without chemical modification or add-on. While, the patterning process is a bottom up approach for living creatures, it can easily be replicated using top down microelectronics production technologies. However, a key challenge is the scale of the patterning areas (from cm² up to m²) and flat surfaces. We report here the use of such micro-nano patterns in order to change the visual aspect of common material over large surfaces. SILSEF and NAPA have developed together a range of processes to functionalize surfaces for hydrophobicity, diffraction or antireflection. These technologies can be used on areas from mm² to m² on flat and hemispheric surfaces. Combined with effective characterization process developed internally, we aim to bring micro nano patterning to a range of industrial applications from fashion textile to windows glass. We show here functional patterning for decoration using diffractive or diffusive optics or water repellent surfaces as depicted on Figure 1.