Space and wavelength multiplexing of holographic fields in longitudinal and transverse planes using waveguide metasurfaces

Waveguide-integrated metasurfaces, subwavelength scatterers patterned atop planar waveguides, offer a compact platform for three-dimensional (3D) holography, near-eye AR/VR, and on-chip photonics. In this work, we design and experimentally demonstrate a waveguide-metasurface capable of multiplexing holographic images of different colors at different spatial planes-either at the same elevation (transverse plane, i.e., plane perpendicular to the propagation direction) or along the direction of propagation (longitudinal plane, i.e., plane parallel to the propagation direction). Our approach enables multi-wavelength, multi-plane holography within a single metasurface by combining a Band-Limited Angular Spectrum (BAS) formalism with an Optical Rotation Angle (ORA) algorithm. Experimentally, we first demonstrate multi-wavelength single-transverse-plane holography, projecting the letters "U," "O," and "T" with correlation coefficients of 70-80% and PSNR < 28 dB, followed by multi-wavelength, multi-transverse plane holography with correlation values of 65-82% and PSNR < 25 dB. We further achieve wavelength- and plane-multiplexed holography, displaying digits "1-4" across two transverse planes with 70-82% fidelity and PSNR up to 31 dB. Finally, we realize longitudinal multi-wavelength holography, demonstrating a 50/50 beam-splitter (λ = 532 nm) and a reciprocal beam-combiner (λ = 635 nm) with 72-74.6% correlation. This robust, fabrication-friendly scheme establishes a versatile route toward compact, multi-plane, multi-color holography for integrated photonics and immersive AR/VR systems.