Discovery Magazine

Phased Antenna-coupled Detector Arrays for THz and IR Imaging

The purpose of this research is to advance optical-antenna-coupled detector technology to enable next-generation THz and IR lensless imaging arrays. In order to deliver on this objective two critical goals are identified; (1) to increase the THz/IR sensitivity and collection efficiency of optical-antenna-coupled detectors through the design of IR impedance matching networks integrated with optical antenna designs, and (2) the development of THz/IR waveguides/phase shifters integrated into coherently interconnected optical-antenna-coupled detector arrays.

Impedance matching between the optical antenna and the detector is identified as being of critical significance for increased sensitivity in antenna-coupled THz/IR detectors. To date investigations of THz/IR antenna-coupled detection have been limited by impedance mismatch, which is dependent on the detector architecture and, particularly in the case of diode detectors, gives rise to reflection and reradiation of a substantial portion of received power. Optical antenna designs that include in their design parameters such as the ability to tune reactive components, as well as designs that render impedance that are much greater than ever required at rf and microwave, portions of the spectrum of antenna design for many years, require novel investigation, accounting for the at-frequency dispersive and loss material properties and development of new designs.

Low-loss waveguides, with integrated phase control, are required to achieve sufficiently large capture cross-sections in order to render high resolution imaging arrays. Novel waveguiding designs are sought in order to overcome the inherent THz/IR material losses. Novel designs, including phonon-enhanced waveguides, surface mode waveguides, impedance surfaces, and leaky-wave optical antennas are investigated.  

 The proposed research holds the potential for tremendous impact in both THz and IR imaging by enabling lens-less imaging focal-plane arrays (FPA) with integrated pixel-level optically controlled beam-steering, which significantly reduces weight, volume, and cost compared to classical lens-based imagers.