Numerical Investigation of Metal-Organic-Framework Coated Long-Period Fiber Grating for CO2 Gas Detection

We propose a novel sensor design utilizing metal-organic-framework (MOF) coated long-period fiber grating (LPFG) for carbon dioxide (CO
2
) gas detection. This sensor exploits the coupling between the fundamental core mode (LP
01
) and the higher-order cladding mode (LP
07
). Both modes exhibit distinct spectral variations in their propagation characteristics when CO
2
is adsorbed in the MOF layer due to their differing penetration depths within the MOF. Consequently, the phasematching point is shifted, yielding an 8 nm wavelength shift in the transmission dip.