This review discusses a variety of fiber-optic-based H 2 sensor technologies since the year 1984, including: interferometer technology, fiber grating technology, surface plasma resonance (SPR) technology, micro lens technology, evanescent field technology, integrated. This review discusses a variety of fiber-optic-based H 2 sensor technologies since the year 1984, including: interferometer technology, fiber grating technology, surface plasma resonance (SPR) technology, micro lens technology, evanescent field technology, integrated. In com-parison to other gaseous or liquid energy sources, special security requirements have to be considered for applications with hydrogen, because additionally to fire hazard under certain conditions an explosive air hydrogen mixture can arise from leaks in tanks or piplelines. Here, a compact optical fiber hydrogen sensing system with high sensitivity and quick response rate is proposed in. We present a novel fiber optic hydrogen sensor with fast response fabricated from a graphene–Au–Pd sandwich nanofilm and an ultrashort fiber Bragg grating. When the measured hydrogen concentration was increased from 0 to 4.