Long period fiber grating for biosensing: an improved design methodology to enhance add-layer sensitivity

Abstract

We present our theoretical study on the design of LPFG sensor where its add-layer sensitivity is enhanced. addlayer sensitivity quantifies the sensitivity of the sensor to the changes taking place within few tens of nanometers around the receptor molecules. Two different methodologies: the use of dual overlay layer and tailoring of the intermodal separation between two cladding modes, have been used to enhance the add-layer sensitivity. Using coupled mode analysis we compute several examples to carry out a detailed comparative analysis between the results obtained, focusing on the cladding mode near mode transition.