H₂ Sensing Based on a Pd-Coated Tapered-FBG Fabricated by DUV Femtosecond Laser Technique

Improved performance of fiber optic hydrogen sensor based on WO3-Pd2Pt-Pt composite film and self-referenced demodulation method

“…Therefore, the value of I 1 /I 2 increases quickly with the increase of hydrogen concentration in the gas chamber. The response time for hydrogen sensor is no more than 20 s at room temperature of 25 • C, which is a significant improvement when compared with the reported work [12][13][14][15][16][17][18][19][20][21]. The quick response rate of the hydrogen sensor can be attributed to the amorphous structure of WO 3 and intensive optical power focused on the core of single mode fiber.…”

“…Many researches have been focused on exploring hydrogen sensors with alternative solution [4,5]. Optical fiber hydrogen sensing technology [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] is one of the hotspots due to its intrinsic safety and anti-electromagnetic interference. Although these hydrogen sensors have good selectivity, their sensitivities (in air) are still much poorer than that of conventional electrode hydrogen sensor, especially under low hydrogen concentrations.…”

Post-processing Fibers for Sensing Applications

“…It was demonstrated that an abrupt taper fabricated in the FBG region presented properties of a FabryPerot cavity; while an FBG written over fused tapers resulted in a phase-shifted FBG. In a different perspective, it was developed a fiber probe sensor for hydrogen detection that was based on a tapered-FBG [10].Multimode interferometer in taper is another topic very interesting for optical refractometer. It was demonstrated a configuration used a silica tube section spliced between two single-mode fibers, where in the splice regions tapers were made in order to allow the light to be guided in the silica tube while the core is formed by air [11].…”

Catalyst-type-an optical fiber sensor for hydrogen leakage based on fiber Bragg gratings

“…These sensing probes employ optical rather than electric power and thus are well suited to the measurement of flammable gases. As a result, a number of optical fiber hydrogen sensors have been proposed, including evanescent-wave absorption devices [6], micromirror optodes [7,8], Mach-Zehnder interferometers [9], surface plasmon resonance (SPR) devices [10] and fiber Bragg gratings (FBG) [10][11][12][13][14][15][16][17][18]. Among these, the FBG hydrogen sensors are most suitable for large scale monitoring since they lend themselves to distributed measurements [11].…”

“…The former type monitors the strain caused by the volume change of a Pd or Pd alloy in the presence of hydrogen gas [12][13][14] and can respond to hydrogen under low oxygen concentrations. However, this type has some deficits, including long response times and delamination of the sensor film with exposure to high concentrations of hydrogen [12].…”