Wafer‐Scale Functional Metasurfaces for Mid‐Infrared Photonics and Biosensing

Abstract

Metasurfaces have emerged as a breakthrough platform for manipulating light at the nanoscale and enabling on￢ﾀﾐdemand optical functionalities for next￢ﾀﾐgeneration biosensing, imaging, and light￢ﾀﾐgenerating photonic devices. However, translating this technology to practical applications requires low￢ﾀﾐcost and high￢ﾀﾐthroughput fabrication methods. Due to the limited choice of materials with suitable optical properties, it is particularly challenging to produce metasurfaces for the technologically relevant mid￢ﾀﾐinfrared spectral range. These constraints are overcome by realizing functional metasurfaces on almost completely transparent free￢ﾀﾐstanding metal￢ﾀﾐoxide membranes. A versatile nanofabrication process is developed and implemented for highly efficient dielectric and plasmonic mid￢ﾀﾐinfrared metasurfaces with wafer￢ﾀﾐscale and complementary metal￢ﾀﾓoxide￢ﾀﾓsemiconductor (CMOS)￢ﾀﾐcompatible manufacturing techniques. The advantages of this method are revealed by demonstrating highly uniform and functional metasurfaces, including high￢ﾀﾐQ structures enabling fine spectral selectivity, large￢ﾀﾐarea metalensesￂﾠwithￂﾠdiffraction￢ﾀﾐlimited focusing capabilities, and birefringent metasurfaces providing polarization control at record￢ﾀﾐhigh conversion efficiencies.ￂﾠ Aluminum plasmonic devices and their integration into microfluidics for real￢ﾀﾐtime and label￢ﾀﾐfree mid￢ﾀﾐinfrared biosensing of proteins and lipid vesicles are further demonstrated. The versatility of this approach and its compatibility with mass￢ﾀﾐproduction processes bring infrared metasurfaces markedly closer to commercial applications, such as thermal imaging, spectroscopy, and biosensing.