Page 25 - december22_112922.indd

TAP TIMES -25- DECEMBER 2022

MIT researchers develop and at room temperature and pressure.

low-cost terahertz camera What’s more, it can simultaneously cap-
ture information about the orientation, or

CAMBRIDGE, Mass. — Terahertz radia- “polarization,” of the waves in real-time,
tion, whose wavelengths lie between which existing devices cannot.
those of microwaves and visible light,
can penetrate many nonmetallic ma- Materials characterization
terials and detect signatures of cer- This information can be used to character-
tain molecules. ize materials that have asymmetrical mol-
ecules or to determine the surface topog-
Many applications raphy of materials.
These handy qualities could lend them- The new system uses particles called
selves to a wide array of applications, in-
cluding airport security scanning, industrial quantum dots, which, it has recently been
quality control, astrophysical observations, found, can emit visible light when stimu-
nondestructive characterization of mate- lated by terahertz waves.
rials, and wireless communications with The visible light can then be recorded by
higher bandwidth than current cellphone
bands. a device that is similar to a standard elec-
tronic camera’s detector and can even be
However, designing devices to detect and seen with the naked eye.
make images from terahertz waves has The device is described in a paper pub-
been challenging, and most existing tera-
hertz devices are expensive, slow, bulky, lished in Nature Nanotechnology, by MIT
and require vacuum systems and extreme- doctoral student Jiaojian Shi, professor of
ly low temperatures. chemistry Keith Nelson, and 12 others.

Two different devices
Now, researchers at MIT, the University of
Minnesota, and Samsung have developed The team produced two different devices
a new kind of camera that can detect tera- that can operate at room temperature:
hertz pulses rapidly, with high sensitivity, One uses the quantum dot’s ability to
convert terahertz pulses to visible light,
enabling the device to produce images
of materials; the other produces images
showing the polarization state of the tera-
hertz waves.

The new “camera” consists of several lay-
ers, made with standard manufacturing
techniques like those used for microchips.
The photons of terahertz radiation have
extremely low energy, Nelson explains,
which makes them hard to detect.

This illustration shows terahertz illumination (yellow curves at “So, what this device is doing is converting
top right) entering the new camera system, where it stimulates that little tiny photon energy into some-
quantum dots inside nanoscale holes (shown as illuminated rings)
to emit visible light, which is then detected using a CMOS-based thing visible that’s easy to detect with a
chip (bottom left) like those in digital cameras. next page