To transmit, manipulate and display information, it is key to have technologies capable of controlling light, and harnessing and transforming colour. Researchers from RMIT and Swinburne University of Technology are taking inspiration from the wings of butterflies, and applying that knowhow to photonics and optics technologies.
Butterfly wings are made of chitin, but the iridescent nature of the wings is due to the nanostructures on them. In some, the chitin is in a gyroid pattern, a 3D periodic stucture made up of an intertwining and curved surface.
Professor Min Gu from the RMIT School of Science teamed up with researchers from Swinburne University of Technology, using optical two-beam super-resolution lithography to create gyroid structures that are inherently 3D, and which are also mechanically stronger than the naturally-occurring gyroids found on butterfly wings.
These structures could allow engineers to control light in photonic and optical technologies. Possible future breakthroughs that may stem from these artificial gyroids include more brilliant visual displays, new chemical sensors, and better storage, transmission and processing of information.
Prior to this, researchers could only use low-resolution techniques to create these nanostructures. They were thus unable to produce artificial gyroid structures with lattice constants comparable to those found in the butterfly wings.
Thus, a key part of this research is the availability of optical two-beam super-resolution lithography, which holds significant advantages over conventional fabrication techniques for such nanostructures: it provides improved resolution, and materials fabricated with this technique have better mechanical strength.
This allowed the researchers to fabricate structures that not just match the capabilities of their natural counterparts, but exceed them — the artificial gyroids have a lattice constant of 360 nm, and a Young’s Modulus that is up to 20 percent higher than their biological counterparts. The strength from this fabrication method means there is less chance of failures caused by the 3D structure collapsing.
The artificially-produced gyroids also have long-range periodicities, and well-defined crystalline boundaries, unlike the imperfect natural structures. This perfections give the chiral properties that are lacking in the natural versions.
This allows the artificial architecture is much more suitable for applications like photonic crystals with optical bandgaps, and miniature chiral beam splitters.
Dr Zongsong Gan from the Swinburne University of Technology, one of the lead authors, says metamaterials made from the artificial gyroid should also have tuneable nonlinear optical properties and respond to light at ultrafast speeds, making them ideal for high-speed switches.
"Apart from applications in biomimetic photonics, the new gyroid structures could help make more compact optoelectronics because, thanks to their smaller size, larger numbers of devices can be integrated onto a single chip, Dr Gan says.