Super Lensing in the Mid-Infrared

Number 750 #3, October 18, 2005 by Phil Schewe and Ben Stein
http://www.aip.org/pnu/2005/split/750-3.html

Super Lensing in the Mid-Infrared

Physicists at the University of Texas at Austin have made a "super
lens," a plane-shaped lens that can image a point source of light
down to a focal spot only one-eighth of a wavelength wide. This is
the first time such super lensing has been accomplished in a
functional device in the mid-infrared range of the electromagnetic
spectrum.

Historically, lensing required a lens-shaped (that is,
lozenge-shaped) optical medium for bringing the diverging rays coming
from a point source into focus on the far side of the lens. But in
recent years, researchers have found that in "negative permittivity"
materials, in which a material's response to an applied electric
field is opposite that of most normal materials, light rays can be
refracted in such a way as to focus planar waves into nearly a point
-- albeit over a very truncated region, usually only a tenth or so of
the wavelength of the light.

Such near-field optics are not suitable for such applications as
reading glasses or telescopes, but have become an important technique
for certain kinds of nanoscale imaging of large biological molecules
than can be damaged by UV light. The micron-sized Texas lens,
reported at the Frontiers in Optics meeting of the Optical Society of
America, consists of a silicon carbide membrane between layers of
silicon oxide. It focuses 11-micron-wavelength light, but the
researchers hope to push on into the near-infrared range soon.
Furthermore, the lensing effect seems to be highly sensitive to the
imaging wavelength and to the lens thickness.

Gennady Shvets ) says that additional
possible applications of the lens include direct laser
nanolithography and making tiny antennas for mid-IR-wavelength
free-space telecommunications.