Design and Computational Analysis of Optical Fiber Sensor for Refractive Index Monitoring Using FDTD Method

In this paper, a novel multimode structure for refractive index optical fiber sensors is presented. The fiber core has an etched and refractive index that is monitored by environmental variations. The analyte is placed into the core medium. In this platform, there is no need for high power intensity on incident light. The changes of propagated modes are investigated to detect of refractive index. The proposed fiber sensor is simulated with a finite difference time domain method. The numerical results illustrate that the presented fiber sensor has an extra spectral response and suitable sensory specifications. So, themaximum sensitivity of the pristine and optimized structures is obtained at 3300 nm/RIU and 3400 nm/RIU, respectively. Therefore, it can be done for refractive index monitoring applications. One of the main obtained results of the proposed sensor is that it is label-free.