Mid-IR evanescent-wave absorption spectra of thin films and coatings measured with a ∼50-μm-thick planar Ge waveguide sensors

James J. Stone, Mark S. Braiman, Susan E. Plunkett

Research output: Contribution to journalConference article

2 Scopus citations

Abstract

We have fabricated IR-transmitting Ge waveguides as supported single crystals 30-100 μn in thickness. These waveguides are useful as internal reflection elements for evanescent-wave absorption sensing and spectroscopy, when used in conjunction with a Fourier transform infrared microscope. This combination affords great sensitivity to small numbers of IR-absorbing molecules near the waveguide surface, and is especially useful for analyzing thin coatings on small-area substrates. For example, we have selectively observed absorption bands, as high as 20x the noise level, from the adhesive layer of a 0.07 mm2 piece of Scotch tape without observing absorption from the backing. By comparing spectra taken using 70- and 30-μm thick waveguides, we demonstrate a clear increase in sensitivity to small samples with decreasing waveguide thickness.

Original languageEnglish (US)
Pages (from-to)371-377
Number of pages7
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume3105
DOIs
StatePublished - Dec 1 1997
Externally publishedYes
EventChemical, Biochemical and Environmental Fiber Senors IX - Munich, Germany
Duration: Jun 16 1997Jun 18 1997

Keywords

  • Attenuated total reflection
  • Chemical sensor
  • IR microscope
  • ZnS coating

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Fingerprint Dive into the research topics of 'Mid-IR evanescent-wave absorption spectra of thin films and coatings measured with a ∼50-μm-thick planar Ge waveguide sensors'. Together they form a unique fingerprint.

  • Cite this