|
A
photonic band gap crystal produced
by a colloidal crystallization
technique using sized, template
spheres. |
Not long ago, theory and experiments
failed to agree on the question of
how light propagates in crystals.
But in 1990, researchers at Ames Laboratory
proved the theorists correct by demonstrating
the existence of structures with a
"photonic bandgap" (PBG), a range
of frequencies within which a specific
wavelength of light is blocked. Scientists
then knew they could custom-design
crystals to trap and manipulate light,
sending it down assigned routes and
even around loops and bends. Among
their novel optical properties, PBG
crystals can manipulate light without
absorption; the energy not emitted
in one frequency region is redirected
into other frequencies, a useful feature
in energy-efficient devices. Early
photonic crystals had a bandgap in
the microwave region of the electromagnetic
spectrum. Using a layered lattice
design and microfabrication capabilities
at Sandia National Laboratories, scientists
moved the bandgap to shorter wavelengths,
in the infrared, for applications
such as optical communications. Ames
also produced computer programs that
allow for the rapid design, analysis,
and optimization of PBG structures.
Scientific Impact:
The Ames' work spawned a growing global
research community and knowledge base
focusing on PBG crystals and related
atomic properties and behavior. The
high accuracy of Ames? theoretical
calculations assists in the interpretation
and design of PBG experiments and
devices, and the layered lattice approach
has been used to make the smallest
PBG crystal ever fabricated.
Social Impact: PBG
crystals could revolutionize the control
of light propagation, emission, and
absorption in optical devices; thus,
they have many potential uses in compact
and efficient sensors, antennas, lasers,
electronics, lighting, solar cells,
and telecommunications equipment (e.g.,
optical switches, waveguides). The
microfabrication method developed
at Sandia is economical and lends
itself to mass production.
Reference: "Photonic
Crystals," M.M. Sigalas, R. Biswas,
G. Tuttle, C.M. Soukoulis, and K.M.
Ho, Wiley Encyclopedia of Electrical
and Electronic Engineering, Volume
16, 345 (John Wiley, 1999).
"Existence
of a photonic gap in periodic dielectric
structures," K. M. Ho, C. T. Chan,
and C. M. Soukoulis, Phys. Rev.
Lett. 65, 3152 (1990).
URL: http://www.public.iastate.edu/~cmpexp/groups/ho/pbg.html
http://www.mdl.sandia.gov/photonics/newsnote1.html
Technical Contact:
Don Freeburn, Office of Basic Energy
Sciences, 301-903-3156
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of Basic Energy Sciences |