Researchers have created new ultrafine films—based on nanoparticles that are more than 80 times thinner than a human hair—that could lead to materials that can holographically archive more than 1000 times the data as a DVD.
The films—just 10 centimeters by 10 centimeters—could enable tiny wearable devices that capture and store 3D images. The films can also be retrieved at speeds of up to one GB per second, about 20 times faster than the reading speed of current flash memory.
“In the future, these new films could be incorporated into a tiny storage chip that records 3D color information that could later be viewed as a 3D hologram with realistic detail,” Shencheng Fu, who led researchers from Northeast Normal University in China who developed the new films, said in a statement. “Because the storage medium is environmentally stable, the device could be used outside or even brought into the harsh radiation conditions of outer space.”
The researchers have been experimenting with metal-semiconductor nanocomposites that could serve as a medium for storing nanoscale holograms with high spatial resolution.
Porous films made with titania and silver nanoparticles could be useful because they can change color when exposed to various wavelengths. A set of 3D images could be recorded at the focus area of the laser beam using a single step.
To record a holographic image into titania-silver films, the researchers used a laser to convert the silver particles into silver cations, which have a positive charge.
“We noticed that UV light could erase the data because it caused electrons to transfer from the semiconductor film to the metal nanoparticles, inducing the same photo transformation as the laser,” said Fu. “Introducing electron-accepting molecules into the system causes some of the electrons to flow from the semiconductor to these molecules, weakening the ability of UV light to erase the data and creating an environmentally stable high-density data storage medium.”
The researchers used electron-accepting molecules in the new films that measured only one to two nanometers, to disrupt the electron flow from the semiconductor to the metal nanoparticles.
They then fabricated semiconductor films with a honeycomb nanopore structure that allowed the nanoparticles, electron-accepting molecules and the semiconductor to interface with each other. This resulted in films that were just 620 nanometers thick.
“Particles made from noble metals such as silver are typically viewed as a slow-response media for optical storage,” said Fu. “We show that using a new electron transport flow improves the optical response speed of the particles while still maintaining the particle’s other advantages for information storage.”
Holographic approaches are also inherently high-density because they record information throughout the 3D volume of the material, not just on the surface, and can record multiple images in the same area using light at different angles or consisting of different colors.
The researcher’s next plan is to test the environmental stability of the new films by performing outdoor tests.
The study was published in Optical Materials Express.