Terahertz vibrational absorption spectroscopy using microstrip-line waveguides

M.B. Byrne, John E. Cunningham, Kasia Tych, Andrew D. Burnett, M. Stringer, Christopher D. Wood, L. Dazhang, M. Lachab, Edmund H. Linfield, A.G. Davies*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

50 Citations (Scopus)
35 Downloads (Pure)


We demonstrate that terahertz microstrip-line waveguides can be used to measure absorption spectra of polycrystalline materials with a high frequency resolution (∼2GHz) and with a spatial resolution that is determined by the microstrip-line dimensions, rather than the free-space wavelength. The evanescent terahertz-bandwidth electric field extending above the microstrip line interacts with, and is modified by, overlaid dielectric samples, thus enabling the characteristic vibrational absorption resonances in the sample to be probed. As an example, the terahertz absorption spectrum of polycrystalline lactose monohydrate was investigated; the lowest lying mode was observed at 534(±2)GHz, in excellent agreement with free-space measurements. This microstrip technique offers both a higher spatial and frequency resolution than free-space terahertz time-domain spectroscopy and requires no contact between the waveguide and sample.
Original languageEnglish
Article number182904
JournalApplied Physics Letters
Publication statusPublished - Nov-2008
Externally publishedYes

Cite this