Integrated THz time-domain devices for real-time hyperspectral tomography

Visible light is a very small fraction of the electromagnetic spectrum, which spans from radio waves at low frequencies to X-rays and gamma-rays at high frequencies. We are all familiar with visible light photography, and that imaging using invisible parts of the spectrum, e.g. X-rays, gives a wealth of additional, different information. There are parts of the spectrum that are less explored and have the potential to reveal more information and facilitate new applications and uses with societal benefits, as X-rays did a century ago. Terahertz (THz) radiation lies between microwaves and infrared light and has many potential uses in medical imaging, product quality control, safety monitoring, security screening and high-speed communications. Previously, terahertz radiation has been too high a frequency for traditional electronics to generate, control and measure, and too low in frequency for the established optical methods associated with visible and infrared light. A range of technologies have recently emerged to harness THz radiation, which are now leading to real world applications. The UK and Germany have been key players in the development of these remarkable THz technologies over the past 20 years. We are now witnessing THz used for airport security scanners and production line quality control, with emergent applications in medical imaging and atmospheric sensing. Our relentless appetite for high-speed communications is also pushing wireless technologies towards THz frequencies. System cost and sensitivity are two major hurdles that must be overcome to unleash a wider range of applications and more widespread adoption of THz solutions. This project brings together two of the latest technologies from the UK and Germany to tackle these problems: Nanowire semiconductor THz sensors developed in the University of Oxford and custom-designed integrated circuits developed by the University of Stuttgart. The development will be supported by leading research institutes in Switzerland and Australia, and three key THz companies from Germany and the UK. Utilising a high-throughput wafer-scale nanowire device production method, we will develop CMOS-integrated THz sensors with unprecedented performance that are compatible with low-cost THz solutions. This approach will enable the production of large numbers of nanowire detectors to create the equivalent of a colour THz camera. When coupled with low-cost lasers, this camera will make high speed THz hyperspectral and 3D imaging a practical reality. The project’s goals are to: Create THz sensors with antenna, detector, amplification and digital readout all integrated in the same element. Develop efficient broadband nano-scale THz light sources optimised for low-cost ytterbium and erbium-based fibre lasers and capable of uniform large-area illumination. Develop fast and sensitive broadband nano-scale THz sensors optimised for the same lasers. Create optical fibre coupled THz sensor and THz emitter modules compatible with commercial THz spectrometers and make them available to UK and German researchers. Realise large-area chip-scale THz time-domain sensor arrays. Develop integrated digital readouts for time-domain THz sensor arrays. Present two case studies of applications of real-time hyperspectral THz tomography.