When an airplane begins to move faster than the speed of sound, it creates a shockwave that produces a well-known “boom” of sound. Now, researchers at MIT and elsewhere have discovered a similar process in a sheet of #graphene, in which a flow of electric current can, under certain circumstances, exceed the speed of slowed-down light and produce a kind of optical “boom”: an intense, focused beam of light.
This entirely new way of converting electricity into visible radiation is highly controllable, fast, and efficient, the researchers say, and could lead to a wide variety of new applications. The work is reported today in the journal Nature Communications, in a paper by two MIT professors — Marin Soljačić, professor of physics; and John Joannopoulos, the Francis Wright Davis Professor of physics — as well as postdoc Ido Kaminer, and six others in Israel, Croatia, and Singapore.
The new finding started from an intriguing observation. The researchers found that when light strikes a sheet of graphene, which is a two-dimensional form of the element carbon, it can slow down by a factor of a few hundred. That dramatic slowdown, they noticed, presented an interesting coincidence. The reduced speed of photons (particles of light) moving through the sheet of graphene happened to be very close to the speed of electrons as they moved through the same material.
http://news.mit.edu/2016/new-way-turn-electricity-light-using-graphene-0613
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