Compact and Cost-effective Signal Processing Architecture for Biased Coherent Terahertz Detection

In this work, we present a compact, low-cost signal processing architecture specifically designed for air-biased coherent detection (ABCD). Our approach replaces the conventional bulky and expensive analog signal processing chain with a custom-designed peak detector circuit [1], followed by direct analog-to-digital conversion and digital signal processing. By capturing the peak photocurrent generated by the terahertz (THz) field-induced second-harmonic generation signal, the system maintains both temporal resolution and signal-to-noise ratio (SNR) without the need for synchronous demodulation. We demonstrate that this architecture delivers comparable detection performance while significantly reducing system complexity, cost, and physical footprints. The compact form factor enables seamless integration into portable and field-deployable THz platforms, paving the way for high-throughput, cost-efficient THz spectroscopy systems suited for industrial sensing, security screening, and in-situ material diagnostics.