A new color display brings scientists one step closer to metamaterials that mimic the unique optical properties of squid, octopus and cuttlefish skin. Developed at Rice University’s Laboratory for Nanophotonics (LANP), the new full-color display delivers bright red, blue and green hues from 5-µm square pixels that each contain several hundred aluminum nanorods. The new display technology is capable of producing dozens of colors, including rich red, green and blue tones. Images courtesy of Jana Olson/Rice University. “Aluminum is useful because it’s compatible with microelectronic production methods, but until now the tones produced by plasmonic aluminum nanorods have been muted and washed out,” said LANP researcher Dr. Stephan Link, an associate professor of chemistry at Rice. “The key advancement here was to place the nanorods in an ordered array.” The researchers fine-tuned the pixels’ colors in two ways — first by varying the length of the nanorods, and then by adjusting the amount of space between nanorods. This arrangement narrowed the “output spectrum to one individual color instead of the typical muted shades that are usually produced by aluminum nanoparticles,” said LANP graduate researcher Jana Olson. “Because the nanorods in each array are aligned in the same direction, our pixels produce polarized light,” Link said. “This means we can do away with one polarizer in our setup, and it also gives us an extra knob that we can use to tune the output from these arrays. It could be useful in a number of ways.” LANP researchers tune the color output of the arrays by varying the length of the nanorods and adjusting the amount of space between them. In the future, the researchers hope to use the technique to create an LCD. The photonic aluminum arrays would be used in place of colored dyes that are found in most commercial displays, they said. Unlike dyes, these arrays won’t fade or bleach after prolonged exposure to light. This work is part of an Office of Naval Research grant awarded in 2010 for the study of the camouflage properties of cephalopods for incorporation in optical metamaterials. “We hope to eventually bring all of these technologies together to create a new material that can sense light in full color and react with full-color camouflage displays,” said LANP Director Naomi Halas. The findings related to the nanorod display were published in the Proceedings of the National Academy of Sciences (PNAS) (doi: 10.1073/pnas.1415970111). For more information, visit www.rice.edu.