Wavelength‐Division Holographic Multiplexing via Cascaded Metasurfaces and THz‐Spaced Microresonator Frequency Combs

Achieving high‐density wavelength multiplexing is essential for expanding the capacity of optical information processing. However, traditional optical components lack sufficient dispersion control, hindering high‐efficiency, low‐crosstalk wavefront manipulation across densely spaced channels. Here, we overcome this bottleneck by introducing a double‐layer cascaded metasurface architecture engineered via an end‐to‐end differentiable design framework. Through joint optimization, this cascaded design yields a 25‐fold increase in multiplexing density over single‐layer approaches, theoretically enabling 64‐channel holographic multiplexing with a tight 4.3‐nm spacing in the visible spectrum. Furthermore, we experimentally validate this architecture in the infrared band by utilizing a terahertz‐spaced microresonator frequency comb as a multi‐wavelength coherent source. This first‐of‐its‐kind integration of differentiable cascaded metasurfaces with on‐chip microresonator frequency combs provides a compact, highly efficient pathway for next‐generation wavelength‐division multiplexing, high‐capacity data communications, and integrated photonic systems.