Self-assembly of nanostructured glass metasurfaces via templated fluid instabilities

Modern devices require the tuning of the size, shape and spatial arrangement of nano-objects and their assemblies with nanometer scale precision, over large-area and sometimes soft substrates. Such stringent multi-scale and mechanical requirements are beyond the reach of conventional lithography techniques or simpler self-assembly approaches. In this talk, we will demonstrate an unprecedented control over the fluid instabilities of thin glass films as a simple approach for the self-assembly of advanced all-dielectric metasurfaces1,2. We show and model the tailoring of the position, shape, size and interparticle distance of nano-objects with feature sizes below ten nanometers. This simple and versatile approach can generate optical nanostructures over tens-of-centimeters sized rigid and soft substrates, with better optical performance and a resolution on par with advanced lithography-based processes. By a programmable control of the nanoimprinting method and the initial film thickness we show that we can achieve tunable particle size and lattice using the same master Silicon mold. To underline the potential of our approach, we demonstrate various optical phenomenon. Our ability to fabricate the metasurfaces on stretchable substrates without undergoing any lift off process finds application in mechano-chromic sensors. The ability to fabricate quasi 3D structures find application in phase tunable metasurfaces. Lastly, by having an unprecedented control over the lattice and particle size we demonstrate sharp Fano resonances with the highest Quality factor (𝑄.𝐹~300) in the visible to date. Such resonances are exploited to realize high efficiency protein monolayer detection and to generate strong Second harmonic generation highlighting the unprecedented reconciliation between state-of-the-art optical performance and simple self-assembly fabrication approaches. 

References 
[1] 	Self-assembly of nanostructured glass metasurfaces via templated fluid instabilities; Tapajyoti Das Gupta etal. Nature Nanotechnology :14, 320-327,2019 
[2] 	Template assisted dewetting of optical glasses for large area, flexible and stretchable all dielectric metasurfaces; Tapajyoti Das Gupta etal. CLEO 2018.