By replicating the complex micron- and nanometer-scale photonic structures that help give butterfly wings their color, researchers have demonstrated a new technique that uses biotemplates for fabricating nanoscale structures that could serve as optical waveguides, optical splitters and other building blocks of photonic integrated circuits.
Using a low-temperature atomic layer deposition (ALD) process, materials scientists at the Georgia Institute of Technology produced aluminum oxide (alumina) replicas of wing scales from a Morpho peleides butterfly, a bright blue insect native to the rain forests of Central and South America. The artificial wing scales faithfully replicated the physical features and optical properties of the natural wing scales that served as templates.
"We can never come close to the richness of the structures that nature can make," said Zhong Lin Wang, Regents Professor in the Georgia Tech School of Materials Science and Engineering. "We want to utilize biology as a template for making new material and new structures. This process gives us a new way to fabricate photonic structures such as waveguides."
The work has been reported in the American Chemical Society journal Nano Letters. The research was supported by the Defense Advanced Research Projects Agency (DARPA), the U.S. National Science Foundation (NSF) and the U.S. National Institutes of Health (NIH). The Day Butterfly Center at Callaway Gardens in Pine Mountain, Ga., provided the Morpho peleides butterfly specimen.
To create their artificial structures, Wang and colleagues Xudong Wang and Jingyun Huang deposited uniform layers of alumina onto butterfly wing scales one Angstrom at a time using the ALD process. (Huang was a visiting scientist from Zhejiang University, China). They were able to precisely control the thickness of the coating with the number of deposition cycles to which each wing scale template was subjected.