Tufts
University engineers have invented a chip-sized, high-speed modulator that
operates at terahertz (THz) frequencies and at room temperature at low voltages
without consuming DC power. The discovery could help fill the "THz
gap" that is limiting development of new and more powerful wireless
devices that could transmit data at significantly higher speeds than currently
possible.
Measurements
show the modulation cutoff frequency of the new device exceeded 14 gigahertzes
and has the potential to work above 1 THz, according to a paper published
online in Scientific Reports. By contrast, cellular networks occupy
bands that are much lower on the spectrum where the amount of data that can be
transmitted is limited.
The
device works through the interaction of confined THz waves in a novel slot
waveguide with tunable, two-dimensional electron gas. The prototype device
operated within the frequency band of 0.22-0.325 THz, which was chosen because
it corresponded to available experimental facilities. The researchers say the
device would work within other bands as well.
Although
there is significant interest in using the THz band of the electromagnetic
spectrum, which would enable the wireless transmission of data at speeds
significantly faster than conventional technology, the band has been
underutilized in part because of a lack of compact, on-chip components, such as
modulators, transmitters, and receivers.
"This
is a very promising device that can operate at terahertz frequencies, is
miniaturized using mainstream semiconductor foundry, and is in the same form
factor as current communication devices. It's only one building block, but it
could help to start filling the THz gap," said Sameer Sonkusale, Ph.D., of
Nano Lab, Department of Electrical and Computer Engineering, Tufts University,
and the paper's corresponding author.
Journal
Reference:
1.
P. K.
Singh, S. Sonkusale. High Speed Terahertz Modulator on the Chip Based
on Tunable Terahertz Slot Waveguide. Scientific Reports, 2017;
7: 40933 DOI: 10.1038/SREP40933
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