Advancements in Beam Manipulation and Dynamic Control of Electromagnetic Waves Using Metamaterial Arrays and Voltage-Tunable Periodic Structures

Abstract

Traditional beam steering techniques employ both mechanical and non-mechanical methods, finding broad applications in optical communications, displays, image sensors, optical circuits, and laser-based manufacturing systems. However, each approach has inherent limitations. In this thesis, we address these shortcomings through the investigation of various beam steering system designs. Firstly, we explored a mechanical system that utilizes a scanning waveguide driven by an integrated mechanical actuator. This innovation aims to reduce the system's footprint and overcome the limited field of view (FOV) associated with traditional mechanical systems. Secondly, we introduce an electro-optic thin-film polymer beam scanner capable of achieving 2D scanning. This novel approach surpasses mechanical limitations while also exhibiting lower power consumption compared to traditional bulk crystal-based electro-optic devices. To further enhance the performance, versatility, and robustness of the electro-optic scanner, we have recently developed a method of beam manipulation based on phase modulation, employing a voltage-tunable thin-film periodic structure known as the Tunable Gradient Fishnet Metamaterial (TGFMM). This device allows unique control of the optical beam through its discrete elements, facilitating effective beam manipulation. We have developed a model for the TGFMM, analyzing its transmission phase and refractive index to optimize its phase modulation performance and operating frequency. Subsequently, we conducted a numerical study to evaluate the device's beam manipulation capabilities. The optimized design was then fabricated on a flexible substrate, with special attention given to maintaining device robustness. Furthermore, we characterized the prototype TGFMM and experimentally evaluated its beam manipulation performance using a terahertz frequency domain spectroscopy (THz-FDS) system. The results demonstrate successful beam deflection achieved by applying a gradient voltage profile, validating the prototype TGFMM's effectiveness in beam manipulation within the Terahertz (THz) frequency range. This research represents a significant advancement in beam steering technology, providing potential applications in various domains such as wireless communications, imaging, and sensing systems. The innovative techniques and insights presented in this thesis pave the way for more efficient and sophisticated beam steering technologies in the future, providing potential applications in various domains such as wireless communications, imaging, and sensing systems.