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

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.This work was supported by Council of Scientific Research (CSIR), India during the 12th Five Year Plan. Project Nos. ESC-0102 and ESC-0110. The author I. D. Villar thankfully acknowledge the support of the Spanish Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) (TEC2016-78047-R) and the Government of Navarre through the project with reference 2017/PI044