چكيده به لاتين
In this thesis, the output spectrum of the tapered fiber sensor is simulated and experimentally is investigated. In the simulation section, the effect of geometric parameters including diameter and angle and then the effect of adsorbent layer thickness on the sensitivity of the sensor were investigated with Mathematica software and staircase method. It was found that, for fixed angle, increasing the taper diameter from 12 to 28 micrometers reduces the sensitivity of the sensor. On the other hand, for fixed taper diameter and length, there is an optimum point for taper angle that the sensitivity becomes maximum.
The effect of adsorbent layer thickness on sensitivity depends on the refractive index of the adsorbent layer: If the refractive index of the adsorbent layer is less than the refractive index of the fiber, as the thickness of the adsorbent layer increases, the sensitivity of the sensor increases. However, if the refractive index of the adsorbent layer is greater than that of the fiber, we will have optimal points for the sensitivity of the sensor as the thickness of the adsorbent layer increases.
In the experimental section, in order to confirm the results of the simulation, the effect of diameter and angle has been investigated. For this purpose, palladium coating is used to detect hydrogen gas. By decreasing the diameter, an increase in sensitivity can be observed, which is consistent with the simulation results. In our experiments, fibers with diameters 15 and 26μm were examined and it was observed that a diameter of 15μm is more sensitive than 26μm. In order to investigate the effect of the tapering angle on the sensitivity of the sensor, tapered fibers with a length of 11 mm were used. The experimental results showed that by increasing the tapering angle from 1 to 3 degrees, the sensitivity of the sensor is increased.
In addition, in order to investigate the effect of adsorbent layer thickness on sensor sensitivity, poly pyrrole coating was used to detect dimethyl methyl phosphate. The effect of adsorbent layer thickness on sensor sensitivity is consistent with the simulation results.
