arXiv subjects

Feng-Jun Li

Publications and source records attributed to Feng-Jun Li.

2 recordsLinked to original sources

arXiv2025

A 160 {\deg} x 160 {\deg} Dynamic Holographic Meta-Projector

Holography can reconstruct immersive light fields for virtual and augmented reality by modulating optical wavefront. Due to huge pixel sizes, current spatial light modulators (SLMs) have small field-of-view (FOV) for holographic displays. Despite various methods for etendue expansion, the largest full-screen FOV for dynamic holography is only 70 {\deg} X 70 {\deg}, which remains insufficient for large-scale, high-resolution, three-dimensional displays. Here, we report a pixel-interpolation-assisted holographic meta-projector that substantially expands the FOV by integrating multiple subwavelength metasurface pixels within each microscale pixel of a traditional SLM. Leveraging large-angle diffraction of the metasurface and implementing k-space distortion correction for ultra-wide angles, we experimentally demonstrate dynamic holographic image reconstruction with a FOV of 160 {\deg} X 160 {\deg} -equivalent to a system numerical aperture of 0.985-at a high framerate of 60 Hz, surpassing the temporal resolution threshold of human vision. This system represents the state-of-the-art near-full-screen holographic dynamic display, thereby opening the door to high-dynamic-range and large-FOV holographic displays.

physics.optics↗

arXiv2021

Perfect diffraction metagratings supporting bound states in the continuum and exceptional points

Resonance coupling in non-Hermitian systems can lead to exotic features, such as bound states in the continuum (BICs) and exceptional points (EPs), which have been widely employed to control the propagation and scattering of light. Yet, similar tools to control diffraction and engineering spatial wavefronts have remained elusive. Here, we show that, by operating a suitably tailored metagrating around a BIC and EPs, it is possible to achieve an extreme degree of control over coupling to different diffraction orders in metasurfaces. We stack subwavelength metallic slit arrays on a metal-insulator-metal waveguide, enabling a careful control of the coupling between localized and guided modes. By periodically tuning the coupling strength from weak to strong, we largely tailor the overall spectrum and enable the emergence of singular features, like BICs and EPs. Perfect unitary diffraction efficiency with large spectrum selectivity is achieved around these singular features, with promising applications for arbitrary wavefront shaping combined with filtering and sensing.

physics.optics↗