Terahertz focal plane arrays employing heterostructure backward diodes integrated with folded dipole antennas

In this paper, we present the design, simulation, fabrication and initial characterization results of terahertz (THz) focal plane arrays (FPAs) employing Sb-based heterostructure backward diodes (HBDs) integrated with lens-coupled folded-dipole antennas (FDAs). For single array element design, FDAs with high embedding-impedances have been designed for impedance matching to HBDs without additional matching network. Under impedance matching conditions, a maximum detector responsivity of ~21,000 V/W could be obtained for single array pixel at 200 GHz. In order to expand the single element design into full 2-D THz FPAs, the off-axis radiation patterns of the FDA mounted on an extended hemispherical silicon lens have been analyzed using the ray tracing technique. In addition, mutual coupling between two adjacent FDAs has been studied using full-wave simulation. The above results along with initial array fabrication and device characterization results have demonstrated the potential to achieve room-temperature, high-performance and large-scale FPAs for THz imaging applications.