Column: Microwave and mmWave
Time to Bridge the Terahertz Gap
By Greg Rankin, Houston-based freelance writer with more than 10 years of experience writing about the microwave and mmWave industries.
R
esearchers at IMRA turn to THz-capable components in pursuit of a molecular clock that can more accurately measure time, down to the second.
T e scientifi c community is striving to bring
life to the so-called “dead zone”, a region of the electromagnetic (EM) spectrum between electronics and optics. T is band, oſt en referred to as the “terahertz gap”, resides between 100 GHz and 30 THz. Below it lies the microwave bands that are increasingly being consumed by numerous commercial and scientifi c applications. Above it, infrared devices like thermal imaging, night vision equipment, and fi ber-optic transmission and data storage are now common. Within the terahertz technology gap
lies a vast reserve of bandwidth poised for development. However, the development of user-friendly technologies capable of generating, manipulating, and detecting radiation within these frequency bands is not only technically challenging but has also been hindered by the limitations of available THz- capable components. IMRA, a creative research and innovation
organization that develops essential technologies for industrial use, was able to overcome many of the issues associated with the THz regime recently when working at frequencies above 300 GHz. Researchers at the Colorado-based laboratory were looking to use molecules as stable frequency references that could potentially be used as clocks. “Let me be clear, we are not redefi ning the
defi nition of a second,” explains Research Scientist James Greenberg, a program manager at IMRA. “T e defi nition of the second is always going to be a laboratory experiment that’s very complex, but there are many reasons why you do need a practical implementation to more accurately measure a second.” While it may seem esoteric to be concerned
about the accuracy of a second, several future industries stand to benefi t from this functional research; a noteworthy one includes space travel.
26 October 2024
www.electronicsworld.com
Motivating the move “Future space navigation will benefi t from this type of research,” adds Greenberg. “You can’t use GPS in space because there is no “G” in your global positioning system. So, if you want to know where you are, you need extremely good inertial sensors and timekeeping.” While space travel is provocative and
exciting, the urgency to bridge this terahertz gap is currently being driven by numerous other, more terrestrial, applications. For
example, the development of 6G wireless communication and beyond. Higher frequencies between microwave radiation and infrared light are essential for achieving wider bandwidths which will enable faster data rates and reduce overcrowding. “T e carrier frequency of 300 GHz is 150
times larger than two gigahertz where the current cellular network is today,” explains Greenberg. “So, take the number of devices we currently have and imagine multiplying that by a factor of 150. T at’s the biggest driver in going into a higher frequency.” Other industries that stand to benefi t from
better utilization of the THz band include radio astronomy, GPS navigation systems, navigating in areas where GPS is unavailable like underwater, caves, mines, etc. Another breakthrough will include terahertz
radar which will provide the missing link between traditional radar and lidar - Light Detection and Ranging. For example, lidar can see objects much smaller than radar, but cannot see through clouds. Terahertz radar can perform better than lidar in inclement weather while improving the angular resolution of traditional radar. It is also complimentary to both radar and lidar in that some materials exhibit diff erent opacities in the diff erent spectral ranges.
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