8 x 8 Terahertz Photoconductive Antenna Array and Parallelized Signal Acquisition System for Fast Spatially Resolved Time Domain Spectroscopy

Abstract: Terahertz (THz) technology is promising in several applications such as imaging, spectroscopy and communications. Among several methods in the generation and detection of THz waves, a THz time domain system (TDS) that is developed using photoconductive antennas (PCA) as emitter and detector presents several advantages such as simple alignment, low cost, high performance etc. In this work, we report the design, fabrication and characterization of a 2-D PCA array that is capable of detecting both the amplitude and phase of the THz pulse. The PCA array is fabricated using LT-GaAs and has 8 channels with 64 pixels (8x8). The infrared probe beam is steered and focused towards each pixel of the PCA array using a spatial light modulator (SLM). The measured photocurrent (amplitude and phase) from each channel is recorded separately and the frequencies up to 1.4 THz can be detected. Furthermore, the parameters such as directional time delay of the THz pulse, crosstalk between the channels etc., were characterized. Finally, we show that the proposed 2D PCA array design is flexible and can be used for accelerated THz spectral image acquisition.