In the movie Black Panther (2018), there is a hologram image communication scene. Meta-materials enable communication using holograms. Professor Noh Joon-seok (ME, CE) and Prof. Noh’s research team have developed meta-hologram optical elements that can produce different hologram images simultaneously. The research result was published on the cover of the Jan. 2020 issue of Nanoscale Horizon.
While television or beam projectors have only delivered information on the intensity of light, holographic technology can store information on the intensity and phase of light, allowing images to be replayed in a three-dimensional space. Meta-materials can then be used to control the intensity and phase of light by changing size, and shape of the nanostructure. Meta-holograms, which are only 300 to 400 nanometers in size, can implement hologram images with very high quality.
Current meta-hologram devices form images when light enters one direction, whereas when light enters the other direction, it does not. To solve this problem, the research team used two types of meta-surfaces. One type of meta-surface had phase information when light joined from the front, and another type of meta-surface was designed to work as light progressed from the rear. The results confirmed that different holographic images can be generated in real-time depending on the direction of the light's progress. In order to overcome the low-efficiency shortcomings of the existing meta-hologram, the research team also incorporated the dual magnetic resonance and antiferromagnetic resonances that occur inside a silicon nano story column into the nanostructure design. Meta-holograms, which were produced this way, have a high diffraction efficiency of more than 60 %, allowing them to observe very clear images with their eyes. In addition, since the newly developed meta-hologram uses silicon, it can be produced using existing semiconductor processes. Meta-holograms, which operate in both directions, are expected to be able to be a hologram platform that can provide a variety of information simultaneously to multiple users in different locations, beyond showing a single image of information in a limited location.