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A carbon crystal that might eventually be used to make circuits which use
light beams instead of electric currents has been developed by electronics
company AlliedSignal. Researchers took a synthetic version of the gemstone opal
and filled the spaces in its lattice with carbon. They then chemically removed
the gemstone, leaving the carbon in a form they dub “inverse opal”. The
resulting crystal, described in Science (vol 282, p 897), can strongly
diffract visible light, a quality the researchers have exploited to build an
optical switch. The researchers are hopeful that their switch might operate well
with infrared radiation—but they stress that much more work is needed to
make a viable alternative to the transistor.