摘要
Two-dimensionally periodic Janus structures possess identical structural periods along two orthogonal directions while maintaining asymmetric contour profiles within each unit cell, enabling anisotropic optical responses that differ from those of conventional periodic structures. However, systematic experimental investigations of their diffraction characteristics under multiple incident conditions remain limited. In this study, a scalable single-photomask fabrication process is developed to produce square-centimeter-scale two-dimensionally periodic Janus microstructures on silicon wafers. A custom-built high-resolution three-axis scatterometer is employed to characterize diffraction efficiencies and spatial diffraction-energy distributions under different azimuth angles, zenith angles, and polarization states. The experimental results reveal pronounced anisotropic diffraction behavior and strong sensitivities of diffraction efficiency and diffraction distribution to incident conditions, particularly azimuth angle and polarization state. The proposed structures also exhibit a large number of measurable diffraction orders and highly directional diffraction-energy redistribution. The diffraction characteristics are further found to depend strongly on the relationship between structural period and incident wavelength, suggesting opportunities for wavelength-selective and near-infrared photonic applications. The strong azimuth-dependent diffraction behavior and anisotropic energy redistribution also indicate the potential of the proposed structures for angular sensing, optical alignment, directional beam control, and angular-selective photonic devices.
[Display omitted]
•Two-dimensionally periodic Janus microstructures fabricated on silicon.•High-resolution scatterometry reveals anisotropic diffraction distributions.•Diffraction efficiency depends strongly on azimuth angle and polarization.•Higher diffraction orders exhibit unexpectedly high efficiencies.•Janus structures enable controllable directional optical responses.