Monolithic Spin‐Multiplexing Metalens for Dual‐Functional Imaging

Abstract Optical microscopic imaging technology is an essential tool for exploring and understanding the microcosmic realm. Among various imaging modes, bright‐field and spiral‐phase‐contrast imaging are widely used, each capable of extracting distinct morphological information from target objects. However, conventional microscopic imaging devices and systems typically operate in a single mode or require additional modules for mode switching. Here, we present a monolithic photonic spin‐multiplexing metalens operating in the red and near‐infrared regions, which leverages a spin‐multiplexed point spread function to seamlessly switch between bright‐field and spiral‐phase‐contrast imaging modes by simply adjusting the spin state of illumination light. The device demonstrates operational efficiency of up to 80% and imaging resolution better than 4.4 µm (228 lp mm −1 ) in both modes. The metalens's dual‐functional imaging performance is validated with both amplitude‐type (custom‐made metallic patterns) and phase‐type (frog tongue epithelium cells and onion epidermal cells) objects. This work provides a viable solution for compact, lightweight, and easily switchable multi‐functional microscopic imaging systems, opening new avenues for applications in biomedical imaging, clinical diagnostics, and material characterization.