Economist:
Traditional lenses focus light by taking advantage of
refraction. By varying the width of the lens, one can change
the path of the photons and, hence, the amount of refraction. A
new lens, however, created by Federico Capasso and his
colleagues of Harvard University, uses the quantum effects of
nanostructures to focus light through a flat surface by
absorbing the photons, holding on to them for a short time, and
then releasing them. Capasso's team used electron-beam
lithography to create a pattern of concentric rings of antennae
from a 60-nm-thick layer of gold on a silicon wafer. By varying
the shape and separation of the antennae, the researchers were
able to vary the length of time each ring would trap the
photons before re-emitting them, which resulted in a focused
beam of light. Because the distance between the antennae must
be shorter than the wavelength of the light, the lens currently
only works with monochromatic light. Nevertheless, the lens
could be very useful in single-color laser optics, where
variances inherent in glass lenses can decrease lasers'
effectiveness.
