“…To overcome the drawback of traditional biosensor which is usually time consuming, complicated, labeling required and hazardous, fiber optic sensing technology has been proposed by employing fiber Bragg gratings (FBGs), long period gratings (LPGs), and tilted fiber gratings (TFGs) with the advantages of label-free, real-time, multiplex and in-line determination (Wang and Wolfbeis, 2013;James and Tatam, 2003;Albert et al, 2013;Cusano et al, 2014;Zhou et al, 2004). However, the major challenge in fiber sensor field is the lack of sensitivity for applications with small biomolecules and low concentration of analyte (Fan and White, 2011;Canning, 2009). To improve the biosensing performance, techniques have been developed to accelerate the device sensitivity, for instance by cladding etching, side polishing and fiber tapering (Chen et al, 2005;Jang et al, 2009;Zhao et al, 2004;Ding et al, 2005).…”