Generating color 3-D images with designed reflective
metasurfaces under incoherent illumination

As part of an international collaboration with
Southern University of Science and Technology in Shenzhen (China),
London Centre for Nanotechnology researchers at King’s College
London have developed a novel way of generating color 3-D images
using a reflective metasurface performing through the entire
visible spectral range. Metasurfaces are 2-D engineered materials
typically made of subwavelength elements, which provide excellent
control over the shaping of optical wavefronts via the manipulation
of polarisation, phase and amplitude of the light. Unlike typical
metasurface-based holography techniques, the developed method does
not rely on interleaved nanostructures for wavelength multiplexing
or wavelength-dependent off-axis illumination. Instead, the
researchers used specially-designed identical aluminium
nanostructures to achieve a high metasurface efficiency across the
visible spectrum, including the three main RGB colors. A
combination of specular and diffuse reflections was employed to
generate images of 2-D structures with 3-D effects. The true
perception of a 3-D object through shading effects is therefore
ensured by an adequate change in the brightness of the reflected
light from the flat metasurface in response to variations in the
illumination or observation angle. In contrast with 3-D holograms,
this structure performs under incoherent
illumination.