| Abstract: | A comparative study has been carried out on the detection of gases with the use of attenuated total internal reflection spectroscopy in a multimode step index, based on parabolic, linear, and exponential-linear tapered fibers with porous cladding. Using geometric optics, an expression has been derived for the time dependent evanescent absorbance as the gas diffuses through the cladding. It has been shown that the relative evanescent absorbance depends on the taper profile and taper ratio. For a given taper profile, as the taper ratio increases, the response time of the sensor decreases. Further, the sensor with the exponential-linear taper profile has less response time than those with the parabolic and linear profiles in cases of a particular taper ratio. |
