title: Micro-structured femtosecond laser assisted FBG hydrogen sensor.
abstract: We discuss hydrogen sensors based on fiber Bragg gratings (FBGs) micro-machined by femtosecond laser to form microgrooves and sputtered with Pd/Ag composite film. The atomic ratio of the two metals is controlled at Pd:Ag = 3:1. At room temperature, the hydrogen sensitivity of the sensor probe micro-machined by 75 mW laser power and sputtered with 520 nm of Pd/Ag film is 16.5 pm/%H. Comparably, the standard FBG hydrogen sensitivity becomes 2.5 pm/%H towards the same 4% hydrogen concentration. At an ambient temperature of 35°C, the processed sensor head has a dramatic rise in hydrogen sensitivity. Besides, the sensor shows good response and repeatability during hydrogen concentration test.
authors.forename: Joseph Muna
authors.initials: JM
authors.lastname: Karanja
authors.forename: Yutang
authors.initials: Y
authors.lastname: Dai
authors.forename: Xian
authors.initials: X
authors.lastname: Zhou
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Minghong
authors.initials: M
authors.lastname: Yang