In the electromagnetic spectrum just between the microwaves that we use in our WiFi and Bluetooth devices and the infrared light there is a mostly unexplored region, named the TeraHertz (THz) gap, consisting of electromagnetic (EM) waves with frequencies comprised between 0.1 to 10THz, which is waiting to be exploited.
THz radiation may have amazing technological applications. These waves have the ability to penetrate opaque surfaces — for example, scanning luggage — at much higher resolutions than currently possible with non-ionising radiation. Many biological chemicals also have spectroscopic signatures in this range, allowing for easier identification of chemicals in biotechnology applications. Concrete, wood and other structural material are rather transparent thus allowing THz to penetrate and provide information on the ageing and potential collapse of large infrastructures.
While affordable THz laser sources are available on the market since the demonstration of the first quantum cascade THz laser by a group of Italian scientists in 2002, partner of this proposal, the development of affordable and lost cost THz detectors for imaging (the equivalent of the CCD for the visible light) was much slower. The bulky array of gear currently used to measure terahertz waves is clunky and expensive, making it impractical outside of a lab.
The GRANT project proposes, on the short-term scale, to use graphene and plasmonics to demonstrate an array of sensors that translate the EM power in temperature and thus into the deformation of a thin membrane that can be then detected optically using a compact-disk read-out analogy. The GRANT approach offers temperature independent performance, low cost, large sensing areas, simplified read-out and last but not least spectral sensitivity, thus realising a “colour CCD” in the THz region.
On the long-term scale, the GRANT sensors will be optimised, industrialised and, finally, delivered on the market. These light and small cameras will be then assembled and interfaced together with portable and energy efficient THz sources to realise portable and integrated THz inspection systems. Indeed, opposite to the imaging system operating with near infrared and visible light, THz natural sources are too weak to be used for imaging. The so conceived light, portable and autonomous THz inspection systems will equip unmanned vehicles and drones enabling a low cost and effective monitoring in many different fields, from large infrastructure such as bridges, railways, buildings to the status of cultivated field and the maturation of crops, with a significant impact on the society wealth and safety.