Advanced material platforms for holographic applications of photonic metasurfaces

Abstract

Metasurface holographic applications such as imaging, sensing, data encryption and biophotonics are promising for more advanced photonic devices. However, most prevailing material platforms are constrained to rigid substrates with transparency windows at λ > 500 nm, where absorption losses become significant at shorter wavelengths. This thesis demonstrates rigid and flexible material platforms to realise holographic metasurfaces functioning at shorter wavelengths across the visible spectrum. In particular, it presents zirconium dioxide metasurfaces as a novel material platform, all-polymeric metasurfaces, and incoherent light metasurfaces. Pillar with top and air-hole meta-atoms configurations, operating in transmission across the visible spectrum, are introduced.

Zirconium dioxide metasurfaces, characterised by a high refractive index, hardness, and biocompatibility, are systematically designed, fabricated, and experimentally measured. These metasurfaces are utilised for holographic image projection and lab-on-chip optical trapping, employing a retrieval algorithm for hologram design. The integration of these lab-on-chip devices has the potential to replace conventional bulky objective lenses, thereby advancing optics integration.

All-polymeric holographic metasurfaces are designed, fabricated, and experimentally characterised using a novel single-material meta-atom design adaptable to various materials. Specifically implemented with SU-8, these metasurfaces are applied to achieve conformable holographic image projection. Their potential for mass-scale production is highlighted by the low fabrication cost and design simplicity, exploiting nanolithography methods.

Metasurfaces designed to operate with incoherent light sources are developed, fabricated, and partially characterised. The design methodology is described. The initial experimental results are rewarding, but further investigations are required to enhance their performance. These findings are promising to extend the applicability of these incoherent metasurfaces for out-of-lab applications. The advancement of holographic devices, including their materials, operational wavelengths, and excitation methods, will pave the way for advances in the field.