World's thinnest hologram developed

Interactive 3D holograms are a staple of science fiction, but the challenge is to develop holograms that are thin enough to work with modern electronics. Now, scientists from RMIT University and the Beijing Institute of Technology have designed a nano-hologram that is simple to make, can be seen without 3D goggles and is 1000 times thinner than a human hair.

Conventional holograms modulate the phase of light to give the illusion of three-dimensional depth. Writing in the journal Nature Communications, the researchers explained, “To integrate holography with modern low-dimensional electronic devices, holograms need to be thinned to a nanometric scale.

“However, to keep a pronounced phase shift modulation, the thickness of holograms has been generally limited to the optical wavelength scale, which hinders their integration with ultrathin electronic devices.”

The researchers have now broken this thickness limit with a 25 nm hologram based on a topological insulator material — a novel quantum material that holds the low refractive index in the surface layer but the ultrahigh refractive index in the bulk. The topological insulator thin film acts as an intrinsic optical resonant cavity, which can enhance the phase shifts for holographic imaging.

“Our nano-hologram is also fabricated using a simple and fast direct laser writing system, which makes our design suitable for large-scale uses and mass manufacture,” said RMIT’s Distinguished Professor Min Gu, leader of the research team.

The study was co-authored by Dr Zengyi Yue, also from RMIT, who said the next stage of the research “will be developing a rigid thin film that could be laid onto an LCD screen to enable 3D holographic display”.

“This involves shrinking our nano-hologram’s pixel size, making it at least 10 times smaller.”

As explained by Professor Gu, “Integrating holography into everyday electronics would make screen size irrelevant — a pop-up 3D hologram can display a wealth of data that doesn’t neatly fit on a phone or watch.

“From medical diagnostics to education, data storage, defence and cybersecurity, 3D holography has the potential to transform a range of industries and this research brings that revolution one critical step closer.”