Different phase matching schemes of terahertz wave generation using periodic poled lithium niobate for real-world applications

Terahertz (THz) wave generation through periodic poled lithium niobate (PPLN) has gained significant attention due to its potential applications in spectroscopy, imaging, communication, and security screening. Among various nonlinear optical materials, lithium niobate (LiNbO 3 ) has emerged as a promising medium for efficient THz generation due to strong nonlinear optical properties and wide transparency range. However, achieving efficient energy conversion requires effective phase matching to overcome phase velocity mismatch between the pump and the generated THz waves. Several phase-matching schemes have been explored to optimize THz generation. This review comprehensively discusses these schemes, analyzing their theoretical principles, experimental implementations, and practical applications. A comparative analyze is also provided to highlight the advantages and limitations of each approach. The presented literature aims to guide researchers in selecting appropriate phase-matching configurations for THz generation.