Nanoimprint-based subwavelength multifunctional optical windows: from visible to longwave infrared applications

We report on nanoimprint and plasma etching technologies development for high-density sub-wavelength surface structuration at a scale from 1.5μm to 200nm or below, to get multifunctional windows (of size ~2”-3”) offering both outstanding optical and fluidic properties. Such windows are of interest for outdoor surveillance systems, which need to operate whatever the environmental conditions. We demonstrate the realization of multifunctional surfaces enabling antireflection and water repellency properties on different optical materials, i.e. glass/silica, silicon and germanium, for applications from visible to longwave infrared domains. Illustration of such multifunctional window advantages for imaging is provided thanks to its integration in front of a MWIR camera and image analysis in presence of water droplet.