An efficient method for determining transmission characteristics of superstructure fiber Bragg grating and its use for multiparameter sensing

• A mathematical model of superstructure fiber Bragg grating(SFBG) developed.
• Forward-backward core, forward core-forward/backward clad mode coupling analysed.
• SFBG-Transmission /reflection coefficients obtained by finite difference method &TMM.
• Simultaneous sensing of multiple physical parameters investigated.

We propose an efficient approach for determining the transmission characteristics of periodic superstructure fiber Bragg grating (SFBG). In the analysis, the core mode and circularly symmetric cladding modes have been considered for mode coupling. The fiber Bragg grating (FBG) sections and phase shift sections of SFBG have been formulated using coupled-mode equations. The transfer matrices for both the sections have been determined using finite difference method. The modulation of transmission characteristics of SFBG under the perturbation of multiple physical parameters (e.g. strain, temperature etc.) have been investigated numerically. We have simulated the transmission characteristics of SFBG under the simultaneous application of strain & temperature in the range of 0 to 1200 μɛ and 30 to 90 °C. The results obtained show a good agreement when compared with experimental data.