Nonlocal polarization conversion device composed of catenary meta-surface

Nonlocal metasurfaces have attracted significant attention in recent years due to their potential for narrowband operation, which effectively suppresses interference and crosstalk from non-resonant wavelengths, making them highly suitable for applications in nonlinear optics, augmented/virtual reality (AR/VR), and related fields. The key to achieving high-performance nonlocal metasurfaces lies in balancing local phase manipulation and nonlocal resonance excitation, requiring the designed structure to simultaneously possess high polarization conversion efficiency (TLR) and a high-quality factor (Q). Addressing these requirements, this study proposes a design scheme for a nonlocal metasurface operating in the near-infrared band, based on catenary meta-atoms. Leveraging the superior continuous phase modulation capability and rotational robustness of the catenary structure, this design achieves a polarization conversion efficiency of 91.7% and a quality factor of 190 at a wavelength of 1300nm. Theoretical analysis further reveals that the high TLR originates from the synergistic interplay of hybrid resonances involving the quasi-bound state in the continuum (Q-BIC), magnetic dipole (MD), magnetic quadrupole (MQ), and electric dipole (ED). The significant enhancement of the Q factor is attributed to the precise control of the optical field distribution mediated by the structural period and asymmetry parameter of the catenary meta-atoms. This design strategy paves the way for realizing efficient nonlocal wavefront control devices and related metasurfaces.