Biological and chemical sensing at terahertz frequencies

Abstract

This thesis present the studies of terahertz applications including measuring water content in leaf sample and guided wave components, aimed at the development of next-generation terahertz systems. In chapter 2, a study of the methods for measuring leaf water content using terahertz time domain spectroscopy measure continuously the water content status of the sample. A few different wavelengths of a near infra-red LED as 1450 nm, 875 nm, 1050 nm, and 1200 nm also were used in this experiment to make a comparison of the method that fits best for measuring the water status. In chapter 3, a physical structure of a microstructured capillary as an optical waveguide that guides electromagnetic waves in the optical region as a function of the transport medium is discussed in term of mode profiles and attenuation. In chapter 4, perforated thin nickel films with periodic conical hole arrays were used to study the surface modes and the excitation of spoof surface plasmon polaritons is demonstrated in the terahertz transmission spectra of the periodic sub wavelength hole arrays. Surface modes can be supported by both metallic surfaces with different nonlinear dispersion curves which result in spectral interferences in a near field region when the surface modes couple out of the waveguide into free space. In this thesis; the THz waveguides is used to explore the guiding mechanism of an anti-resonant optical waveguide.

Date of Award	24 May 2017
Original language	English
Awarding Institution	University of Bath
Supervisor	Steven Andrews (Supervisor)