Researchers at the Naval Research
Laboratory (NRL) have fabricated photonic bandgap (PBG) nanochannel
glass materials for use in the development of a new class of
extremely compact and efficient opto-electronic devices. The
new devices will have widespread use in both military and commercial
applications. The research team consists of Dr. Armand Rosenberg,
Ms. Elizabeth Bolden, and Dr. Brian Justus, of the Optical
Sciences Division. This work is funded by the Office of Naval
Research.
According to Dr. Rosenberg,
"Structures
that exhibit photonic bandgap optical effects are composed of
alternating layers or rows of dissimilar materials. The thickness
of the alternating layers is on the order of the wavelength of
light. By manipulating the structures of these materials, it
becomes possible to engineer materials with customized optical
properties, suitable for a variety of applications. A major application
area is controlling the propagation of light in opto-electronic
devices, similar to how the flow of electrons is controlled in
semiconductor devices. The size of present optical and opto-electronic
devices could be greatly reduced and their efficiency increased
if the propagation of light could be better controlled and optical
losses due to scattering are eliminated. The novel PBG materials
we have developed will enable the miniaturization of such optical
and opto-electronic devices. In addition, new devices will be
possible based on the unusual combinations of optical and electrical
properties of these novel PBG materials, which are not found
in nature."
The fabrication process for these
nanochannel glass materials begins by inserting an etchable glass
rod into a glass tube and drawing them at high temperatures to
yield filaments having a reduced overall diameter. The filaments
are stacked and re-drawn, further reducing their diameter. Finally,
sections of the nanochannel glass are wafered and polished. Etching
the wafers results in a glass matrix containing a regular array
of sub-micron diameter holes. Additional processing can be performed,
such as filling the holes with another dielectric or semiconductor
material. The PBG nanochannel glass material resulting from this
process is, as Dr. Rosenberg states, "a fundamental building
block of what is, in effect, the optical analog of electronic
integrated circuitry."
The research team reports their
present goal is to optimize the properties of the two-dimensional
PBG crystals currently fabricated at NRL. The NRL team has already
demonstrated PBG nanochannel glass materials with photonic band
gaps varying from infrared to ultraviolet wavelengths. According
to Dr. Justus, co-inventor of the nanochannel glass materials,
"The specific optical properties of these PBG materials
are
highly dependent on their physical characteristics, such as the
symmetry, structure and composition of the layered materials.
Slight modification of these characteristics can significantly
enhance the observed photonic band gap effects."
The research team reports, "photonic
bandgap structures embedded with nonlinear optical materials
show promise in the development of optical switches and limiters
having improved performance." Optical limiters can be used
to protect the human eye against accidental or hostile damage
from lasers.Optical
Sciences Division researchers, Drs. Horn-Bond Lin and
Anthony Campillo, have recently reported the first demonstration
of optical limiting in such a structure. In a related project,
Drs. James Shirk and Richard Pong, also of NRL's
Optical Sciences Division, are developing more advanced optical
limiters that are fabricated by introducing phthalocyanine nonlinear
absorbing materials, developed by Dr. Art Snow of NRL's
Chemistry Division, into the nanochannel structure of the PBG
materials. Research team members report, "the optical limiters
resulting from this process are projected to give 100- to 1000-fold
better eye protection than is currently possible."
"We envision that the payoffs
resulting from this research will include the fabrication of
next- generation optical sensors and miniaturized optical systems;
high-speed opto-electronic components for high-bandwidth communication;
low noise, high gain optical amplifiers; thresholdless/low-threshold
lasers; identification systems based on engineered optical properties;
and efficient directional antennas for RF/microwave devices,"
concluded Dr. Rosenberg.
The U.S. Naval Research Laboratory is the Navy's full-spectrum corporate laboratory, conducting a broadly based multidisciplinary program of scientific research and advanced technological development. The Laboratory, with a total complement of nearly 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 85 years and continues to meet the complex technological challenges of today's world. For more information, visit the NRL homepage or join the conversation on Twitter, Facebook, and YouTube.
Comment policy: We hope to receive submissions from all viewpoints, but we ask that all participants agree to the Department of Defense Social Media User Agreement. All comments are reviewed before being posted.