Optical metasurfaces for information efficient nanoscale metrology

The interplay between light and information lies at the core of many foundational technologies that shape modern society, and it continues to drive innovative solutions to the growing challenges of today’s Information Age. The broad field concerned with extracting information about specific system parameters through optical measurements is known as optical metrology, which forms the central theme of this thesis. A particularly significant application domain of optical metrology is the semiconductor manufacturing industry. The most advanced chips consist of intricate networks of components that must be fabricated with sub-nanometer precision. As the demand for more powerful and compact devices increases, so too do the requirements on fabrication accuracy. Consequently, developing optical metrology protocols capable of efficiently extracting structural information from the nanoscale environments that constitute these chips is crucial for ensuring precise process control. In this thesis, we propose several strategies based on nanophotonic concepts to enable information-efficient metrology at the nanoscale. In particular, we investigate the use of metasurfaces—two-dimensional arrays of designer nanoparticles—to perform accurate measurements on complex nanostructured systems. We further examine how metasurfaces transduce information into the far field and identify detection modalities that optimally retrieve this information. Finally, we explore structured illumination strategies, demonstrating how an incident wavefront can be tailored in concert with metasurface design to achieve optimal sensing performance.