An intriguing article about making an object partially
transparent to red light by stimulating it at its
resonant frequency. What would it take to make it
TOTALLY transparent?
http://www.aip.org/enews/physnews/1997/split/pnu344-2.htm
INDUCED TRANSPARENCY IN A SOLID OBJECT . An atom
generally moves between two energy states by absorbing
or emitting a photon---a red-light photon to take one
example.
If one of those states is itself a doublet of closely
spaced states (the energy difference corresponding to
a microwave photon, say), then an interesting
interference effect can occur.
By shining microwaves at the atom, resonance between
the twin states becomes paramount, and the atom
forgets about absorbing or emitting red light. In
effect the atoms become transparent to red light.
This electromagnetically induced transparency has
previously been demonstrated in gases and figured in
the Nobel Prize-winning effort to produce dark-state
atoms---see Update 343.
Now the effect has been achieved in a solid by
scientists at Wayne State University, who reported a
20% drop in the absorption of light in ruby when they
also shone microwaves at the resonance frequency into
their sample (Zhao et al., Physical Review Letters, 28
July 1997).
It is unlikely that this method will allow one to see
through thick objects since the microwave power would
have to be prohibitively high. The process might,
however, create useful modifications in the material's
refractive index.
( Physics World, October 1997; Science, 15 August )
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