Sensor with 100,000 times higher sensitivity could bolster thermal
imaging
Better detection of microwave radiation will improve thermal imaging, electronic warfare, radio communications

Date:
October 1, 2020
Source:
U.S. Army Research Laboratory
Summary:
New research developed a new microwave radiation sensor with
100,000 times higher sensitivity than currently available commercial
sensors.

Researchers said better detection of microwave radiation will enable
improved thermal imaging, electronic warfare, radio communications
and radar.



FULL STORY ========================================================================== Army-funded research developed a new microwave radiation sensor with
100,000 times higher sensitivity than currently available commercial
sensors.

Researchers said better detection of microwave radiation will enable
improved thermal imaging, electronic warfare, radio communications
and radar.


========================================================================== Researchers published their study in the peer-reviewed journal Nature. The
team includes scientists from Harvard University, The Institute
of Photonic Sciences, Massachusetts Institute of Technology, Pohang
University of Science and Technology, and Raytheon BBN Technologies. The
Army, in part, funded the work to fabricate this bolometer by exploiting
the giant thermal response of graphene to microwave radiation.

"The microwave bolometer developed under this project is so sensitive
that it is capable of detecting a single microwave photon, which is the smallest amount of energy in nature," said Dr. Joe Qiu, program manager
for solid-state electronics and electromagnetics, Army Research Office,
an element of the U.S.

Army Combat Capabilities Development Command's Army Research
Laboratory. "This technology will potentially enable new capabilities for applications such as quantum sensing and radar, and ensure the U.S. Army maintains spectral dominance in the foreseeable future." The graphene bolometer sensor detects electromagnetic radiation by measuring the
temperature rise as the photons are absorbed into the sensor. Graphene
is a two dimensional, one-atom layer thick material. The researchers
achieved a high bolometer sensitivity by incorporating graphene in the microwave antenna.

A key innovation in this advancement is to measure the temperature rise
by superconducting Josephson junction while maintaining a high microwave radiation coupling into the graphene through an antenna, researchers
said. The coupling efficiency is essential in a high sensitivity
detection because "every precious photon counts." A Josephson junction
is a quantum mechanical device which is made of two superconducting
electrodes separated by a barrier (thin insulating tunnel barrier, normal metal, semiconductor, ferromagnet, etc.) In addition to being thin,
the electrons in graphene are also in a very special band structure in
which the valence and conduction bands meet at only one point, known as
Dirac point.

"The density of states vanishes there so that when the electrons receive
the photon energy, the temperature rise is high while the heat leakage
is small," said Dr. Kin Chung Fong, Raytheon BBN Technologies.

With increased sensitivity of bolometer detectors, this research has
found a new pathway to improve the performance of systems detecting electromagnetic signal such as radar, night vision, LIDAR (Light Detection
and Ranging), and communication. It could also enable new applications
such as quantum information science, thermal imaging as well as the
search of dark matter.

The part of the research conducted at MIT included work from the Institute
for Soldier Nanotechnologies. The U.S. Army established the institute
in 2002 as an interdisciplinary research center to dramatically improve protection, survivability and mission capabilities of the Soldier and
of Soldier-supporting platforms and systems.


========================================================================== Story Source: Materials provided by U.S._Army_Research_Laboratory. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Gil-Ho Lee, Dmitri K. Efetov, Woochan Jung, Leonardo Ranzani,
Evan D.

Walsh, Thomas A. Ohki, Takashi Taniguchi, Kenji Watanabe, Philip
Kim, Dirk Englund, Kin Chung Fong. Graphene-based Josephson
junction microwave bolometer. Nature, 2020; 586 (7827): 42 DOI:
10.1038/s41586-020-2752-4 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201001133221.htm

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