Two-Dimensional Metaphotonic Devices for Ultra-Compact Holographic Displays and Nanosensors

Abstract

Rationally designed artificial nanostructures, or optical metasurfaces, open up new horizons in the field of optics and photonics, called metaphotonics. Metaphotonics with 2D metasurfacaes enables diverse intriguing optical applications such as invisibility cloaking, zero/negative refractrive index, super-resolution imaging and wavefront engineering. The metaphotonics field, which has been researched since the early 2000s, is currently undergoing a transitional period from the field of science to the field of technology. With the expansin of understaning of the various physical interactions between light and nanostructures, and the development of small laboratory-scale devices for proof of concept, it was possible to verify the practical applicability of metaphotonic devices. However, in order to utilize the metaphotonic devices in daily basis beyond such laboratory-level technology verification, the following important pending issues must be addressed.

1) Selection of materials capable of mass production and and at the same time realizing high-efficiency optical elements (or low loss dielectric materials) 2) Multifunctional device designs with a single layer optical device 3) Active nanophotonic platforms that can modulate optical characteristics in real time 4) Development of core application technology that can be applied to real life 5) Development of sub-10 nm fabrication process and large-scale fabrication process

This dissertation introduces various approaches that can solve such issues, and at the same time discusses the ultra-compact holographic displays and nanosensors applications based on 2D metaphotonic devices. In Chapter 1, I will briefly describes the concept of metaholograms and nanosensors with pending issues on each field. In Chapter 2, I will introduce basics of holography, phase modulation in metasurfaces and dielectric material platform for high-efficiency holographic applications such as reflective Fourier hologram and image hologram. In Chapter 3, I will present multifunctional metaholograms which can encode multiple pieces of information in a single device, or multiplexed metahologram. As a proof of concept, spin-encoded and direction-multiplexed metaholograms will be presented. In Chapter 4, I will show active nanophotonic platforms with designer liquid crystals. The stimuli-responsive liquid crystas are incoprtated with multiplexed metaholograms enabling novel applications such as interactive holographic displays and heat/pressure monitoring photonic sensors. In Chapter 5, I will discuss holographic metasurface gas sensors that can promptly detect harmful volatile gases and provide visual alarm instantaneously. Also, one-step nanocasting process is introduced for flexible and attachable metasurface platforms. In Chapter 6 and 7, I will present unconventional nanofabrciations for single digit nanometer scale fabrications, called capillary-force-induced collapse lithography and cascade domino lithography, and its productions of plasmonic nanoantennas for nanosensors applications. In the last Chpater, I will conclude the dissertation with an outlook and remaining challenges in the field of 2D metaphotonics.

I strongly believe my efforts in developing different types of 2D metaphotonic devices including ultra-compact holographic displays for volumetric display applications and nanosensors for advanced biological and spectroscopy applications will advance future nanoscale optics and photonics, materials science and broad nanoscience and nanotechnology.