Anomalous Enhancement of Volume and Surface Refractive Index Sensitivity of Fiber Bragg Grating Sensors with Deposition of Gold Nanoparticles

In this paper, it has been shown that the refractive index (RI) sensitivity of higher-order cladding modes of a fiber Bragg grating (FBG) can be enhanced significantly with the deposition of gold nanoparticle over the surface. A detailed numerical study is being accomplished in this work. Initially, the sensitivity of higher-order cladding modes is evaluated with a dedicated multi-layer numerical model of FBG. Subsequently, thin nanoparticles of gold are being considered over the surface of FBG. A Four-layer model is employed for the computation of sensitivity of cladding modes of FBG. Almost a `2.5' fold enhancement of sensitivity is found with the utilization of gold nanoparticles. This proposed FBG sensors can be utilized in highly sensitive chemical and biological sensing applications.