Optoelectronic Multistatic Terahertz Imaging FMCW Radar

We demonstrate a 3D multiple-input multiple-output (MIMO) terahertz (THz) imaging system. It uses an optoelectronic architecture comprising two continuous-wave lasers to generate and detect the THz field. Frequency tuning is achieved by sweeping the output frequency of one laser and mixing it with a fixed frequency laser. The optical output is fiber coupled, amplified and split into 16 channels which are used to illuminate an array of eight continuous wave THz transmitters and eight THz receivers. Each transmitter can be switched on and off individually via the applied bias voltage such that parallel sampling of the intermediate frequency (IF) at the receivers allows to record every transmitter and receiver combination individually. Numerical postprocessing of this data on a general purpose graphics processing unit (GPGPU) allows the reconstruction of the entire scene as a 3D-voxel array.