Most of us have at least a passive acquaintance with light-emitting
diodes or LED. We see them in electronic equipment, and we know that
they emit light because the two elements that make up the diode are
chemically releasing energy as they are stimulated by electricity or
some kind of radiation. The actual amount of light given off is very
low because extracting the light efficiently is very hard to do, so the
light we see from the old LED is typically red--the low energy end of
In 2001, Alexei Erchak and his colleagues at MIT developed a two-dimensional photonic crystal which allowed a greater emission of light over the standard LED. This crystal has a triangular lattice of holes etched into the upper cladding layer to enhance the emission of light. These layered surfaces are called Bragg reflectors and are high-emission devices with multiple uses.
Peter Vukusic and Ian Hooper at the University of Exeter have found that the swallow tail butterfly has an identical structure they use to signal each other. The wing scales on the butterflies' wings act as two-dimensional photonic crystals. These crystals are infused with pigment so that the ultraviolet light is absorbed by the pigment and then re-emitted as a brilliant blue-green light by fluorescence. The pigment in the wings is located in the crystals where evenly-spaced micro holes exist. The butterfly does not have a semiconductor in it, but uses a structure similar to a Bragg reflector to reflect all the fluorescent light upward. The design of the system is doubly efficient by its design. Dr. Vukusic says, "When you study these things and get a feel for the photonic architecture available, you really start to appreciate the elegance with which nature put some of these things together." We would suggest that the elegant design is the product of an intelligent designer who tells us that we can know there is a God "through the things He has made" (Romans 1:20).
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