Nonlocal Huygens' Meta-device Based on a Bound State in the Continuum and Kerker Condition

Project: Research

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Description

Meta-devices, the advanced flat optical devices, composed of arrayed subwavelength structures, can flexibly manipulate electromagnetic waves' phase, amplitude, polarization, etc., with capabilities much beyond traditional bulk devices. Professor Din-Ping Tsai (Co-I of this project) has first demonstrated the high-efficiency continuous broadband operation meta-device, achromatic meta-lens. It is implemented by employing the special design of integrated-resonant units for phase compensation, in which each meta-atom has an independent local response. On the other hand, under broadband illumination, the bandpass-operated meta-devices with nonlocal collective responses over numerous meta-atoms also possess various special applications, such as optical nonlinearity, bio-medical imaging, virtual reality display, and quantum optics. However, the known nonlocal meta-devices still face the challenges of low-quality factors, low efficiency, complicated configuration, and low-dimension light-field manipulation due to the limitation of the physical mechanism and design methods. For example, the reported theoretical polarization conversion efficiency is limited to ~25% for transmitted or reflected light under circularly polarized light. Here we propose a novel solution to efficiency-enhancing dielectric nonlocal Huygens' meta-device. The physical mechanism of the quasi-bound state in the continuum (q-BIC) and the Kerker condition are considered simultaneously to achieve high-quality factors and efficiency-enhancing for narrowband operation. The metaatom is designed as a nano-cylinder with an offset nanohole within a hexagonal lattice. Each meta-atom is rotated based on the Pancharatnam-Berry geometric phase arrangement to constitute the phase profile of the meta-devices for tailoring the wavefront. The symmetry break can excite the q-BIC, whose quality factor can be manipulated by adjusting the geometric parameters. Meanwhile, we further introduce the Kerker condition by coupling the q-BIC with other multipole modes. Our novel composite design method can offer a higher polarization conversion efficiency (>60%) at the resonant wavelength with a quality factor of >200 than the simple nonlocal meta-device. The proof-of-concept demonstration will be designed, fabricated, and characterized via the proposed meta-device for focusing and imaging in visible, also called nonlocal Huygens' meta-lens. Our proposed nonlocal meta-lens' expected experimental working efficiency would be at least 7 times higher than the reported academic results for nonlocal meta-lens. The successful accomplishment of this project offers a vital approach for efficient resonant meta-devices implementation and application. Our nonlocal Huygens' meta-device advantages are compact size, high efficiency, customized narrow working band, and power consumption. The significant impact of this project can promote the revolution of next-generation optical devices and systems, such as advanced display technology, personal wearable devices, and nonlinear/quantum applications.

Detail(s)

Project number9043560
Grant typeGRF
StatusActive
Effective start/end date1/09/23 → …