Compact room temperature terahertz imaging: Towards on-chip integration

On-chip integration of secondary diffractive optics and bow-tie-shaped InGaAs-based terahertz detectors is presented. Zone plates were produced directly on the bottom surface of a 500 μm-thick semi-insulating InP substrate employing direct laser write technique. Integration of the bow-tie detector and the zone plate allows to enhance detection more than one order of magnitude at 0.76 THz. Good correlation between experimental data and 3D finite-difference time-domain simulation results is found. It is confirmed that observed detection enhancement is caused mainly by the focusing performance of the zone plate.