A 0.18 cubic centimeter 3D meta-holographic zoom micro-projector.

Meta-holography has become a frontier hot spot of photonics, thanks to the rapid advancement of nanofabrication. Tunable meta-holography significantly enhances information capacity and meets the growing demands of adaptive imaging, offering tremendous application prospects in fields such as optical storage, augmented and virtual realities, and biology. However, the existing meta-holography predominantly relies on 2D projection, with a small and non-adjustable image size. Here, we propose a 3D meta-holographic zoom micro-projector by integrating a high-resolution metasurface with a tailored liquid lens, and the size of the demonstrated micro-projector is only 0.18 cm3. A 3D Fourier meta-hologram generation method is proposed, which overcomes the limitation of the traditional Fourier meta-hologram in realizing 3D projection. By proposing a small-sized zoom liquid lens, the projector achieves 3D zoom projection, with the size and projection distance of the meta-holographic image extending to the decimeter scale, a feat unattainable by previous meta-holographic projection. This flexible and miniaturized 3D fingertip zoom micro-projector is anticipated to have broad applications in portable and wearable devices as well as biomedical apparatus.