Presentation Information
[8a-A22-1][JSAP-Optica Joint Symposia Invited Talk] Underwater Huygens Meta-Optics
〇Ming Lun Tseng1 (1.Natl. Yang Ming Chiao Tung Univ.)
Keywords:
metasurface,GaP,underwater photonics
Metasurfaces are highly promising for underwater photonics, including wireless communication and imaging. However, conventional immersion metasurfaces rely on high-aspect-ratio nanopillars, which suffer from reduced dielectric contrast, fabrication complexity, and mechanical instability in liquid environments. In this work, we demonstrate ultrathin, water-immersed metasurfaces using gallium phosphide (GaP) Huygens’ integrated resonance units (HIRUs) operating at 532 nm. By combining the high refractive index of GaP with particle swarm optimization, we achieve an ultra-compact meta-atom thickness of only 85 nm (~lambda/5). These HIRUs satisfy the generalized Kerker condition, providing high transmittance (>75%) and full 2pi phase coverage. For environmental robustness, the devices are encapsulated in a 300-nm-thick SiO2 layer, providing excellent mechanical protection. We experimentally fabricate the metasurfaces and demonstrate the generation of various underwater structured light beams, including non-diffracting Bessel beams (depth of focus ~2.25 mm), abruptly autofocusing beams, and optical vortices. Sonication and extended immersion tests confirm significantly enhanced durability compared to traditional nanopillar designs. This CMOS-compatible platform offers a scalable and robust solution for advanced underwater nanophotonics.