Theoretical study of the effect of the layer thickness on the sensitivity of tapered fiber optic sensors

In this paper, a comprehensive study was performed to investigate the effect of the absorbent layer thickness on the tapered fiber sensor sensitivity, which leads to the highest sensitivity for the sensor. For this purpose, a staircase method was introduced to investigate the effect of layer thickness on the sensitivity of fiber optic sensors. According to the results obtained from the simulations performed using this method, it was found that the type of variation in the sensitivity of the tapered fiber optic sensor depends on the refractive index of the layer. To investigate the dependence of sensitivity on the layer thickness and refractive index of the layer, two different general cases have been considered. If the refractive index of the layer is smaller than the refractive index of the fiber, it can be seen that the sensitivity increases with increasing the layer thickness. On the other hand, when the refractive index of the layer is greater than the refractive index of the fiber, there are optimal points in the sensitivity plot versus the layer thickness, which demonstrate the highest sensitivities.