Investigation on improving the noise performance of T-ray liquid spectroscopy via double-modulated differential time-domain spectroscopy

Liquid spectroscopy allows analysis of chemical composition and provides a better understanding of the solvation dynamics of various types of liquids. Although it has been shown that liquid spectroscopy using T-rays is feasible, liquid water absorption is still considered to be one of the most challenging problems facing THz imaging and spectroscopy in biomedical applications. The absorption coefficient for liquid water shows a very high THz absorption, 200 cm(-1) at 1 THz. This paper describes a promising novel liquid double-modulated differential time-domain spectroscopy (Double-modulated DTDS) technique to extract the optical parameters with a dual-thickness measurement. The described technique improves on the previous work, by replacing the required sample dithering technique with a rotating spinning wheel resulting in an improved noise performance up to two orders of magnitude.