UA Researchers Design Material that More Effectively Slows Light
Posted: 2015-10-5
Researchers at The University of Alabama designed and made a material that
manipulates the speed of light in a new, more effective way than previous
methods, according to findings recently published in Scientific Reports by
the Nature Publishing Group.
The research by two professors and three grad students in the UA College of
Engineering could help in creating next-generation optical networks and
sensors that rely on variances in the speed of light.
"Slow light will lead to the development of optical buffers and delay lines as
essential elements of future ultrafast all optical communication networks that
could meet the ever-increasing demands for long-distance communications,"
said Dr. Seongsin Margaret Kim, associate professor of electrical and
computer engineering and principal investigator on the research.
"In addition, enhanced interaction of photons with matter by lowering the
speed of light gives rise to reduced power consumption in nonlinear optical
switching devices and ultra-accurate sensing performance of optical
sensors."
Besides Kim, the paper "Impact of Substrate and Bright Resonances on
Group Velocity in Metamaterial without Dark Resonator" is authored by
graduate students Mohammad Parvinnezhad Hokmabadi, Ju-Hyung Kim and
Elmer Rivera along with Dr. Patrick Kung, an associate professor in electrical
and computer engineering.
Parvinnezhad Hokmabadi, the lead author of the published paper, was
partially supported by the UA Graduate Council Creative and Research
Fellowship.
Kim’s research investigates the interaction between light, a form of
electromagnetic waves called photons, and matter to attain combined
spectroscopic sensing and near field imaging capabilities by utilizing
terahertz waves. Terahertz waves exist in the electromagnetic spectrum
between infrared light and microwaves, and are promising for various
applications such as security, chemical and biological sensing, biomedical
imaging, and non-destructive manufacturing inspection.
For the experiment, the research group used terahertz waves, but the
scientific findings can be applied to other wavelengths, including visible
light, Kim said.
The metamaterial
An emerging class of materials, metamaterials consist of specially designed
metal patterns on the substrate, like silicon, whose size, geometry and
orientation can be selected to allow for exotic optical properties The device
fabricated by the UA researchers can be on both flexible substrate and
silicon.
In unencumbered air, light is generally accepted to travel at a constant
speed, but it can be slowed by passing through a material. Water, for
instance, bends, or refracts, light. While the human eye can detect changes
in the speed of light through bended images such as through eye glasses or
curved mirrors, the speed of light is not substantially slower with simple
refraction.
However, the phenomenon called "slow light" is a different sort of
manipulation of the speed of light that can drastically slow and even stop
light waves from travelling, thus reducing what’s called the group velocity.
An emerging class of materials called metamaterials can be engineered with
properties not found naturally, which can be structured to interact with light
to slow or stop it. Unlike the best known methods for slowing light that
involved cold atoms, metamaterials use no energy and are much less
complex to implement. They show promise in various applications such as
filters, modulators, invisible cloaking devices, superlenses and perfect
absorber.
In their lab at UA, the researchers fabricated and measured subwavelength
metal patterns they specially designed on top of a substrate, such as silicon.
Importantly, this metamaterial is flexible and thin. The main thrust of the
paper is explaining how such a thin metamaterial can behave as if it was
1,000 times thicker, which makes highly integrated photonic sensors
possible that could also be realized on flexible substrates.
"We have interests in using such a device in applications of sensing,
communication and imaging," Kim said.
This research was supported by the National Science Foundation.
manipulates the speed of light in a new, more effective way than previous
methods, according to findings recently published in Scientific Reports by
the Nature Publishing Group.
The research by two professors and three grad students in the UA College of
Engineering could help in creating next-generation optical networks and
sensors that rely on variances in the speed of light.
"Slow light will lead to the development of optical buffers and delay lines as
essential elements of future ultrafast all optical communication networks that
could meet the ever-increasing demands for long-distance communications,"
said Dr. Seongsin Margaret Kim, associate professor of electrical and
computer engineering and principal investigator on the research.
"In addition, enhanced interaction of photons with matter by lowering the
speed of light gives rise to reduced power consumption in nonlinear optical
switching devices and ultra-accurate sensing performance of optical
sensors."
Besides Kim, the paper "Impact of Substrate and Bright Resonances on
Group Velocity in Metamaterial without Dark Resonator" is authored by
graduate students Mohammad Parvinnezhad Hokmabadi, Ju-Hyung Kim and
Elmer Rivera along with Dr. Patrick Kung, an associate professor in electrical
and computer engineering.
Parvinnezhad Hokmabadi, the lead author of the published paper, was
partially supported by the UA Graduate Council Creative and Research
Fellowship.
Kim’s research investigates the interaction between light, a form of
electromagnetic waves called photons, and matter to attain combined
spectroscopic sensing and near field imaging capabilities by utilizing
terahertz waves. Terahertz waves exist in the electromagnetic spectrum
between infrared light and microwaves, and are promising for various
applications such as security, chemical and biological sensing, biomedical
imaging, and non-destructive manufacturing inspection.
For the experiment, the research group used terahertz waves, but the
scientific findings can be applied to other wavelengths, including visible
light, Kim said.
The metamaterial
An emerging class of materials, metamaterials consist of specially designed
metal patterns on the substrate, like silicon, whose size, geometry and
orientation can be selected to allow for exotic optical properties The device
fabricated by the UA researchers can be on both flexible substrate and
silicon.
In unencumbered air, light is generally accepted to travel at a constant
speed, but it can be slowed by passing through a material. Water, for
instance, bends, or refracts, light. While the human eye can detect changes
in the speed of light through bended images such as through eye glasses or
curved mirrors, the speed of light is not substantially slower with simple
refraction.
However, the phenomenon called "slow light" is a different sort of
manipulation of the speed of light that can drastically slow and even stop
light waves from travelling, thus reducing what’s called the group velocity.
An emerging class of materials called metamaterials can be engineered with
properties not found naturally, which can be structured to interact with light
to slow or stop it. Unlike the best known methods for slowing light that
involved cold atoms, metamaterials use no energy and are much less
complex to implement. They show promise in various applications such as
filters, modulators, invisible cloaking devices, superlenses and perfect
absorber.
In their lab at UA, the researchers fabricated and measured subwavelength
metal patterns they specially designed on top of a substrate, such as silicon.
Importantly, this metamaterial is flexible and thin. The main thrust of the
paper is explaining how such a thin metamaterial can behave as if it was
1,000 times thicker, which makes highly integrated photonic sensors
possible that could also be realized on flexible substrates.
"We have interests in using such a device in applications of sensing,
communication and imaging," Kim said.
This research was supported by the National Science Foundation.
