Project C08 - Broadband Passive Imaging Components in Silicon Technologies

Principal Investigator: Prof. Dr. Ullrich Pfeiffer, BUW IHCT

It is the objective of this proposal to use the naturally occurring radiation denoted as passive imaging in the millimeter-wave (mm-wave) and sub-millimeter-wave (submm-wave) region of the electromagnetic spectrum to (i) locate objects under conditions of low visibility, and (ii), to provide information about their material composition. The low visibility may be caused by smoke, haze, fog, clouds, or sandstorms, whereas the latter case includes material-specific properties such as the specific emissivity, e.g. how much a surface behaves as a blackbody, the material’s absorptivity, reflectivity and transmissivity. The proposed methods of C08 ultimately enable passive video-rate imaging in a portable lightweight room-temperature passive imager with additional functionality of polarimetric measurements and passive frequency filtering (colour filtering) over a decade of bandwidth spanning from 0.15-1.5 THz. The project builds on the preliminary work on active THz cameras, which are wideband but lack the required sensitivity for passive imaging using the natural ambient terahertz illumination. In the mm-wave band, fundamentally operated circuits relying on the availability of high-gain low-noise amplifiers (LNAs) will be investigated, whereas the non-quasi static direct detector operation will be exploited at the higher submm-wave band.

Major scientific breakthroughs include unseen sensitivity for silicon-based room-temperature operated radiometers (NETD of <0.5 K or NEP <1 pW/√Hz) and multi-band radiometers for the measurement of the spectral radiance of bulk materials in an optimum number of frequency bands (number of colours) over a decade of bandwidth from 0.15-1.5 THz (up to 4 THz in phase III).

In the long-term this goal is technology-aided by the semiconductor industry through continued lateral scaling of semiconductor devices (more Moore) and the research on emerging devices (beyond CMOS). At the same time, this long-term goal becomes attainable through advanced co-design methodologies among circuits, antennas, and optics, which will be applied for global optimization of the imager performance.

C08 enables measurements of the material-specific emissivity. It uses the natural diffuse THz emission and reflection of electromagnetic radiation without the need for active illumination. A breakthrough in radiometer sensitivity (NETD of <0.5 K (or NEP <1 pW/√Hz) is targeted with a compact form factor enabling low-power passive THz cameras in a silicon technology for the first time.