Efficient source-to-fiber coupling method using a diamond rod: Theory and application to multimode evanescent-wave IR absorption spectroscopy

Roy E. Jonas, Mark S. Braiman

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

The use of a diamond rod to couple a blackbody source optically to a chalcogenide glass fiber is described and shown to be useful for evanescent- wave IR absorbance measurements. One end of a short 0.5-mmdiameter diamond rod abuts an optical fiber of the same diameter; the other end is in direct contact with a glowing silicon carbide IR source. The close match of the refractive indices of SiC, diamond, and AsSeTe fiber reduces optical losses at the interfaces, allowing a high overall throughput as well as transmission into the fiber of a wider range of transverse optical modes than is available with the use of through-air focusing methods. Use of the higher-order modes for evanescent-wave spectroscopy leads to increases in sensitivity, due both to increased evanescent pathlength and to a larger number of internal reflections per unit length.

Original languageEnglish (US)
Pages (from-to)1751-1759
Number of pages9
JournalApplied Spectroscopy
Volume47
Issue number11
DOIs
StatePublished - 1993
Externally publishedYes

Keywords

  • Attenuated total reflection
  • Chalcogenide fiber
  • Infrared
  • Remote sensor
  • Spectroscopic techniques

ASJC Scopus subject areas

  • Instrumentation
  • Spectroscopy

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