Cavity ring-down technique for remote sensing

Chemical Sensing Using Fiber Cavity Ring-Down Spectroscopy

Waveguide-based cavity ring-down spectroscopy (CRD) can be used for quantitative measurements of chemical concentrations in small amounts of liquid, in gases or in films. The change in ring-down time can be correlated to analyte concentration when using fiber optic sensing elements that change their attenuation in dependence of either sample absorption or refractive index. Two types of fiber ca...

Cavity Ring-down Biosensing

Cavity ring-down spectroscopy (CRDS) is an established technique for gases sensing that is newly emerging in the field of optical biosensing. This approach measures changes in the rate of decay of light injected into an optical resonator and relates them to optical loss along its length. This principle has recently been adapted for use in liquids, providing a highly sensitive method for quantit...

Cavity-locked ring-down spectroscopy

Spatial domain realization of the cavity ring-down technique in a plane Fabry–Perot cavity

We propose and demonstrate a spatial version of the cavity ring-down concept in which a photon flux decay is displayed along the spatial coordinate at the exit of a plane Fabry–Perot cavity. The photon decay signals are simulated based on a simple theoretical model combining ray optics and diffraction involved in the spatial ring-down generation, which are found to be in good accordance with th...

Evanescent Wave Cavity Ring-down Spectroscopy: a Future Technology for Process Sensing

Evanescent wave cavity ring-down spectroscopy (EW-CRDS) is described. The total internal reflection (TIR)-ring and monolithic folded cavity designs are briefly discussed. The performance of EW-CRDS for trace water vapor detection is evaluated by accounting for surface chemical and physical properties as well as intrinsic resonator properties. INTRODUCTION Cavity ring-down spectroscopy (CRDS) us...