SCATTERINGS | NEWS
Using Nano-Optics to
Control the Phase of Light
S
hose who live in glass houses
shouldn’t throw stones, because glass is brittle compared to
traditional building materials like
concrete. But who wants to live in
a dark bunker made of concrete?
Schott North America Inc. may
have found the best of both worlds.
It has introduced a translucent concrete. The company’s BrightBuild
panels incorporate thousands of
glass fiber-optic strands that transmit light through the concrete.
This isn’t your typical building
concrete. For one thing, it’s not
load-bearing. Another difference is
that the company supplies panels
of the material in custom length and
widths, and in thicknesses up to
about 4 cm. The translucent-buttough glass blocks used in some
security applications are considerably thicker than this, and still brittle
like glass.
Providing daylight to interior
spaces is an obvious application of
the material. It could also be incorporated into structures as a security measure. Because anything
near the backlit panels cast visible
shadows, security elements can
also be incorporated into designs
so that lurkers can’t hide behind
a wall or around a corner made of
the material.
6 | OPN September 2008
(a)
0
(c)
(b)
2
1
0
–1
–2
1
0
0.25
Shift/Period
0.5
–1
(d)
3.1 Mm
T
Phase
DID YOU KNOW?
the phase of the transmitted light by
ometimes, an odd thing happens
180 degrees, while maintaining high
when you shine light at an array of
transmitted intensity.
pinholes smaller than the wavelength
In previous work, they found that the
of the light. Although you’d expect
two layers transmitted the most light in
that very little light would propagate
two conditions. The first occurred when
through the holes, at some wavelengths
the slits were lined up—which makes
a lot more light is transmitted than can
intuitive sense,
be explained
since we’d expect
geometrically.
light that passes
This effect is
through a slit in
due to interacthe first layer to
tions between
easily pass through
the resonance
an aligned slit in
of the incident
the second. But the
light and surface
same amount of
excitations. Now
light was transresearchers at
mitted when the
the University
Micrograph of staggered slits.
second layer was
of Florida and
shifted by half a
elsewhere have
discovered a way to manipulate the phase period so that the slits were staggered.
The researchers simulated both strucof light using arrays of sub-wavelength
tures using rigorous coupled-wave analyslits, while still transmitting more light
sis, which shows some interesting effects.
than expected (Opt. Lett. 33, 1410).
The electromagnetic field distribution
Graduate student Zsolt Marcet in
Ho Bun Chan’s research group built two shows the light coupling from one array
of slits to the next.
arrays of tiny slits in aluminum. They
This sort of structure could be used
demonstrated that the phase of light can
to design tunable sub-wavelength nanobe controlled by sliding one layer to the
optical components that manipulate
side while keeping the other still. The
phase. Possible applications include
two layers are close enough to allow the
biochemical sensing, microscopy and
surface excitations to couple. By changhigh-density optical data storage.
ing the lateral shift between layers from
— Yvonne Carts-Powell
zero to half the period, they changed
Numerical simulation shows (a) the
shift in the phase
of light transmitted
through two layers of
sub-wavelength slits;
(b) electromagnetic
field (EM) distribution
around a single array of
slits; (c) EM distribution
around a double array
of aligned slits; (d) EM
distribution around a
double array of staggered slits.
4.0 Mm
www.osa-opn.org