An infrared absorption spectrometer features an optical microcavity, and a waveguide that evanescently couples light into the microcavity. The optical resonance frequency of the microcavity is tuned to coincide with an atomic or molecular resonance frequency of a selected atom or molecule. In this way,...http://www.google.ca/patents/US6765211?utm_source=gb-gplus-sharePatent US6765211 - Micro-optic absorption spectrometer
