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Theses Doctoral

Dielectric Metasurfaces for Optical Wavefront Manipulation

Shrestha, Sajan

Metasurfaces are a novel class of optical devices, made up of an array of subwavelength scatterers that can allow unprecedented control of an optical wavefront. These devices can be fabricated using conventional nano and microfabrication processes en masse and have thin and lightweight form factor making them ideal for use in compact and miniaturized optical systems. In this thesis, I will first introduce the field of metasurfaces with a historical overview of the research and development in this field. Following the introductory section, I will demonstrate a design for broadband infra-red absorber based on the metasurface platform, demonstrating the ability of metasurface to control broad spectrum of light. Subsequently, optical wavefront engineering capability of metasurfaces is displayed by demonstration of multifunctional metasurface devices, including examples of multiwavelength metasurface lenses and holograms. An example of polarization multiplexed metasurface will also be discussed. As an extension of multiwavelength metasurface lens, a framework for correcting chromatic dispersion inherent in metasurface is presented. I will then demonstrate a strategy to design metalenses with broadband achromatic aberration correction for imaging applications and discuss fundamentals limitations on the extent of chromatic correction that can be achieved. This will lead to a section on multi-element metasurface design for correcting monochromatic aberration in addition to chromatic aberration for compact imaging systems. Finally, I will conclude the thesis with an outlook that points to application areas where metasurfaces, with their thin and light form factor are ideal alternative to replace many conventional optical devices.


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More About This Work

Academic Units
Applied Physics and Applied Mathematics
Thesis Advisors
Yu, Nanfang
Ph.D., Columbia University
Published Here
January 30, 2020