PORTLAND, Ore. Iridescent insects, butterflies and birds have long puzzled scientists with their unique ability to reflect bright colors. Nature's trick is growing nanoscale structures with dimensions that filter light being reflected without dimming light the way conventional filters do.
Researchers at the Georgia Institute of Technology (Atlanta) said they have unearthed the secret of natural liquid crystals that reflect light as bright as a back-lit LCD. Separately, Qualcomm MEMS Technologies Inc. announced it is breaking ground on a manufacturing plant to fabricate its own reflective displays using methods similar to those recently discovered at Georgia Tech.
Professor Mark Burns and doctoral candidate Sean Langelier recently characterized the natural cholesteric liquid crystals in the colorful shells of beetles, discovering that they self-assemble into a complex arrangement of polygonal shapes whose tiny dimensions reflect only two colors of circularly polarized light.
The jewel beetle (Chrysina gloriosa) was studied in detail at Georgia Tech, where researchers discovered that nanoscale structures filtered out all but two distinct circularly polarized color bands--green light at a wavelength of 530 nanometers and yellow light at a wavelength of 580 nanometers. The nanoscale structures worked by mixing three different polygonal shapes--hexagons, pentagons and heptagons--whose percentages were varied depending on the curvature of the insect shell.
Next, the researchers said they plan to characterize the shells of iridescent insects to create unique colors not seen elsewhere in nature.
They also hope their findings about natural iridescence can be harnessed for use in miniature optical and photonic devices. To that end, Qualcomm MEMS Technologies (QMT, San Diego) have been developing what it calls an interferometric modulator (iMoD) display. Qualcomm claims the displays are as bright as back-lit LCDs, but consume power only when the display is changed. On June 2, Qualcomm announced that it was building a dedicated iMoD display facility at Longtan's Science Park (Taoyuan, Taiwan) in collaboration with Cheng Uei Precision Industry Co. Ltd., (Foxlink).
Qualcomm's iMoD display is based on an optically resonant cavity housing a Fabry-Perot etalon, consisting of a thin-film stack and a deformable reflective membrane. Normal ambient light reflects off both the thin-film stack at the top of the cavity and the reflective membrane at the bottom. Phases are controlled to selectively reinforce specific colors, thereby yielding light amplification without the filters and polarizers that cut down on transmitted light from LCDs.