Meta-holography beyond aliasing: an approach utilizing k-space constraint

Meta-holography has gained much attention for enabling wide viewing angles, vectorial manipulation, and dense information encoding in compact spaces, which is pivotal for 3D holography. However, sub-wavelength pixels can cause aliasing, particularly impacting high-resolution 3D image reconstruction with extensive depth ranges due to large diffraction angles. We propose a meta-hologram generation method based on the iterative k-space constraints, concurrently preserving image resolution and fidelity. By introducing dual constraints with a step function and bandwidth limitation, the diffraction propagation is optimized, thus effectively suppressing the aliasing artifacts. Furthermore, the integration of both amplitude and phase loss functions has been implemented. By iteratively refining the calculated complex amplitude toward the target one, the high-fidelity meta-holographic reconstruction can be achieved. To validate the proposed approach, 2500×2500 aliasing-free 3D Fresnel phase-only meta-holography with a pixel size of 0.35μm and a depth of 30 mm has been demonstrated. Results show enhanced resolution and fidelity across different reconstruction distances compared with conventional methods. Notably, the proposed method does not require pre-training, allowing for flexibility in designing meta-holograms without additional operations when diffraction-related parameters are changed. This approach has the full potential of high-quality holography and enables diverse applications such as storage and virtual reality.