Research on Infrared and Terahertz Spectral Characterization Systems

Electromagnetic waves in the infrared (3–11 μm) and terahertz (30–3000 μm) bands resonate absorption reactions with chemical bonds in biological tissues. Combined with spectral characterization systems, relevant pathological tissues can be distinguished. This paper provides an overview of infrared and terahertz spectral characterization systems. Each system has its own advantages in terms of application requirements, and is complementary. Based on different types of infrared radiation sources, the nonlinear crystal tuning spectral characterization system, broadband supercontinuum radiation spectral characterization system, and quantum cascade spectral characterization system are elaborated. Based on the radiation detection mechanism of photoconductive antennas, fiber type and free space optical field modulation terahertz time-domain spectroscopy systems are introduced. By summarizing the system compositions and principles of infrared and terahertz spectral characterization systems, this paper provides reference for scientific researchers to select the corresponding band spectral characterization system.