  Holography plays a crucial role in optics applications, but it traditionally
requires complex setup and bulky devices, being unfavourable for optics
integration. While metasurface-based holograms are ultra-compact and easy to
realize, holographic images generated are mostly restricted to scalar ones,
with a few recent attempts on vectorial holograms suffering from complex
meta-structures and low efficiencies. Here, we propose and experimentally
demonstrate an efficient meta-platform to generate vectorial holograms with
arbitrarily designed wave fronts and polarization distributions based on
ultra-compact metaatoms. Combining GS algorithm and the wave-decomposition
technique, we establish a generic strategy to retrieve the optical property,
i.e., the distributions of reflection phase and polarization-conversion
capability of the metasurface to generate a target vectorial holographic image.
We next design a series of high-efficiency and deep-subwavelength metaatoms
exhibiting arbitrarily designed reflection phases and polarization-conversion
capabilities, and experimentally characterize their optical properties. Based
on these metaatoms, we finally realize a series of meta-holograms that can
generate pre-designed vectorial holographic images upon external illuminations,
and experimentally characterize their working performances. Our work provides a
high-efficiency and ultra-thin platform to generate vectorial holographic
images, which can find many applications in onchip photonics.
