Researchers from Italy, Japan, Great Britain, and Russia have banded together to create a revolutionary new graphene-based terahertz detector. Scientists believe this technology could be used to create faster Wi-Fi, help to improve radio telescopes used for studying objects in space, and even help to create new ways to diagnose dangerous medical conditions.
Although scientists have long hoped to take advantage of the power of terahertz radiation, there have been some factors working against this. Terhahertz radiation, while extremely powerful, suffers from requiring intense cooling, as well as consuming far too much power to be useful.
The trouble with terahertz detection ultimately comes down to size, however. The size of the transistor, or detecting element, comes in at about one-millionth of a meter. The wavelength of terahertz radiation, on the other hand, is about 100 times larger. This means that waves often slide right by the detector without it ever once noticing they’ve been in proximity.
The team of scientists think they’ve a solution to this issue. They designed a photodetector constructed out of bilayer graphene, which was itself enclosed within crystals of boron oxide. The design was then attached to a terahertz antenna.
This set-up allows impurities to be removed to the interior of the flake of graphene, which lets the plasmons within to multiply quickly and easily. A plasmon resonator is then formed by the graphene sheet trapped inside the metal leads. The bilayer graphene structure then allows for a wide range of wave velocity tuning.
Scientists have also managed to design a compact terahertz spectrometer. This device is just a few microns in size. Its resonant frequency can be controlled thanks to voltage tuning.
As if that isn’t impressive enough, researchers also showed that their detector has yet another valuable use. The detector can hold various frequencies as well as electron densities. By measuring these, scientists could uncover further properties possessed by plasmons — and how to utilize them usefully.
“Our device doubles up as a sensitive detector and a spectrometer operating in the terahertz range, and it’s also a tool for studying plasmons in two-dimensional materials. All of these things existed before, but they took up a whole optical table. We packed the same functionality into a dozen micrometers.”