Abstract-Uncertainty in Terahertz Time-Domain Spectroscopy Measurement of Liquids

http://link.springer.com/article/10.1007/s10762-016-0318-1

Terahertz time-domain spectroscopy (THz-TDS) is a significant technique for characterizing materials as it allows fast and broadband measurement of optical constants in the THz regime. The measurement precision of the constants is highly influenced by the complicated measurement procedure and data processing. Taking THz transmission measurement of liquids into account, the sources of error existing in THz-TDS process are identified. The contributions of each source to the uncertainty of optical constants in THz-TDS process are formulated, with particular emphasis on the effect of multilayer reflections and plane wave assumption. As a consequence, an analytical model is proposed for uncertainty evaluation in a THz-TDS measurement of liquids. An actual experiment with a Di 2-Ethyl Hexyl Phthalate (DEHP) sample is carried out to show that the proposed model could be a basis to evaluate the measurement precision of optical constants of liquids.

Abstract-Perfect Broadband Terahertz Antireflection by Deep-Subwavelength, Thin, Lamellar Metallic Gratings

 

Lu Ding Qing Yang Steve Wu Jun Feng Song^,Kazunori Serita Masayoshi Tonouchi, Jing Hua Teng
http://onlinelibrary.wiley.com/doi/10.1002/adom.201300321/abstract
Perfect broadband terahertz antireflection coatings are demonstrated by deep-subwavelength, thin, lamellar metallic gratings both in theory and experiment. Abrupt phase changes introduced by grating to terahertz wave traversing the coated surface can be tuned from 0 to π as a function of grating parameters. At π/2, the impedance difference between two dielectrics is matched and perfect antireflection occurs.