A Sensor With Coating Pt/WO Powder With an Erbium-Doped Fiber Amplifier to Detect the Hydrogen Concentration<sub/>

A highly sensitive hydrogen sensor (HS) coated with Pt/WO3 powder with an erbium-doped fiber amplifier (EDFA) is proposed and experimentally demonstrated. The sensing head is constructed by splicing a short Section of tapered small-diameter coreless fiber (TSDCF diameter of 62.5 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> and tapered to 14.5 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula>) between two single-mode fibers (SMFs). The Pt/WO3 powder adheres to the surface of polydimethylsiloxane (PDMS) film coated on the TSDCF structure, which is sensitive to hydrogen. An EDFA is introduced into the sensor system to improve the quality factor (<inline-formula> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula>-factor) of the output spectrum and thus improve the sensor’s resolution. As the hydrogen concentration varies from 0% to 1.44%, the measured maximum light intensity variation and the sensor’s sensitivity are −32.41 dB and −21.25 dB/%, respectively. The sensor demonstrates good stability with the light intensity fluctuation of < 1.26 dB over a 30-min duration.