Sampling concepts for Photonic THz Homodyne Systems

Continuous-wave terahertz (CW-THz) homodyne systems have emerged as powerful tools for non-destructive testing and spectroscopy across various industries. A critical aspect of these systems is the method used for sampling the THz field, which directly influences the system’s accuracy, speed, and complexity. Here, we provide a comprehensive comparison of the primary sampling techniques employed in CW-THz homodyne systems: optical path length variation, frequency tuning, and phase modulation. The suitability of each method for different applications is evaluated, with particular attention to industrial environments where simplicity, robustness, and cost-efficiency are paramount. We highlight the trade-offs between these sampling approaches and explores recent advancements that aim to optimize THz signal recovery, paving the way for more practical and efficient CW-THz systems.