Narrow bandwidth fiber-optic spectral combs for renewable hydrogen detection

Hydrogen sensors are of great importance to detect leakage in time because the hydrogen-air mixture is highly flammable. Based on optical fiber-based configurations reported so far, using palladium coating only does not meet stringent performance targets, such as fast response time and limited deactivation caused by poisoning. Here, a palladium-gold alloy-coated optical fiber hydrogen sensor, i.e., highly tilted fiber Bragg grating (TFBG), was proposed by using its narrow bandwidth cladding modes whose effective refractive index (ERI) extends to 1.0 where the gas measurement is possible, which led to faster specific hydrogen measurement response time (a shorter stabilization time during the association and dissociation phases less than 20 s and 30 s, respectively) and improved deactivation resistance (higher than 99% per test cycle). Meanwhile, the temperature cross-sensitivity can be eliminated via referencing the target spectral combs to the core mode. We are sure that this promising configuration extends research directions for rapid, repeatable and high deactivation-resistance in hydrogen gas detection.