Hydrogel‐Waveguiding On‐Chip Meta‐Optics for Dynamic Multicolor Holography.

On‐chip integrated meta‐optics hold tremendous potential for optical imaging and display applications compatible with integrated photonic devices. Despite recent endeavors in multi‐dimensional image display, it remains a challenge to realize dynamic holography applications with on‐chip integration scheme and facile accessible tuning approach. Herein, an on‐chip hydrogel‐waveguiding platform with single‐step fabrication is demonstrated for dynamic colorful holography. By exploiting the optical tunable property of the waveguiding hydrogel, the on‐chip hydrogel metasurface enables optical concealment ON/OFF and dynamic dual‐channel holographic switch within 310 ms through a simple exhalation process. Furthermore, utilizing the waveguiding hydrogel dispersion and the correlation between extraction efficiency and relative humidity, a color‐mixed holographic image is encrypted and successfully exhibited at specific humidity condition. Beyond the conventional static on‐chip monochromatic holography, such a dynamic on‐chip hydrogel platform enjoys satisfactory humidity‐responsivity, high integration capability, full‐color potential, and zero‐order diffraction interference‐free, which suggests potential applications in active optical information concealment/encryption, full‐color holography, and next‐generation wearable AR devices. [ABSTRACT FROM AUTHOR]