Integrated-resonant Meta-devices for Wavefront Manipulation

Abstract

Meta-devices, composed of engineered photonic nanostructures known as meta-atoms, have revolutionized flat optics by enabling highly precise control over light’s amplitude, phase, polarization, and spectral properties. However, conventional meta-devices, typically based on single-type meta-atoms, offer limited design flexibility, making it challenging to realize complex optical functionalities such as chromatic aberration correction, wavelength multiplexing, and multiband operation.

To address these limitations, this thesis explores integrated-resonant meta-devices, built upon integrated-resonant units (IRUs) that combine multiple meta-atoms, resonant modes, and optical functions within a building block. This approach provides enhanced design freedom and paves the way for advanced wavefront manipulation across diverse application scenarios.
Focusing first on broadband applications, we present plasmonic IRUs designed for achromatic focusing in the visible spectrum (400–660 nm). By leveraging both local and nonlocal plasmonic resonances, our design achieves a larger phase compensation increased by 50% than previous works. We demonstrate spherical and spiral achromatic meta-lenses based on this principle. Further, by expanding the dielectric IRU library, we identify high-efficiency IRUs that match varying phase compensation needs, yielding a 15% improvement in focusing efficiency over previous designs. These advances significantly enhance the feasibility of compact, full-color optical systems.

For narrowband, wavelength-selective applications, we introduce an all-dielectric IRU-based meta-lens that integrates magnetic dipole and lattice resonances to selectively focus light at 460 nm, while transmitting other wavelengths unaltered, surpassing traditional metallic and color filter approaches. This design achieves a color purity of 90% in simulation and 66% experimentally. Building on this concept, we develop a multi-resonant meta-lens capable of selectively focusing red, green, and blue wavelengths, offering potential opportunities for compact imaging and display systems.

Extending beyond planar integration, we explore out-of-plane integration strategies to realize multifunctional and tunable meta-devices, overcoming the long-standing challenge of achieving both capabilities simultaneously. We demonstrate a meta-device with dual interpretations in both real space and spatial frequency domains, enabling dynamic switching and tuning between a non-diffracting beam and a diffraction-limited focus. This strategy highlights the potential of integrated-resonant meta-devices to expand information capacity and functionality in tunable and integrated optical systems.

Collectively, these contributions establish integrated-resonant meta-devices as a powerful platform for next-generation optical systems. By using both in-plane and out-of-plane integration strategies, this thesis demonstrates frontiers in wavefront control, broadband and narrowband scenarios, and multifunctional optical processing.

Date of Award	22 Dec 2025
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Din-ping TSAI (Supervisor) & Mu Ku CHEN (Co-supervisor)