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    Hydrogen gas sensing using palladium-coated microdisk microresonators
    (SPIE-INT SOC OPTICAL ENGINEERING, 2015) Eryurek, Mustafa; Karadag, Yasin; Tasaltin, Nevin; Kilinc, Necmettin; Kiraz, Alper; Kudryashov, AV; Paxton, AH; Ilchenko, VS; Aschke, L; Washio, K
    An SU-8 polymer microdisk resonator coated with a palladium (Pd) layer and coupled to a single-mode optical waveguide is used to as a hydrogen (H-2) gas sensor. In the presence of H2 a red shift is observed in the spectral positions of the microdisk whispering gallery modes (WGMs) due to the expansion in the Pd lattice. H-2 concentrations below the flammable limit (4%) down to 0.3% could be detected in nitrogen atmosphere at room temperature. For H-2 concentrations between 0.3 1%, WGM spectral positions shifted linearly with H-2 concentration at a rate of 32 pm/%H-2. Average response time of the devices was measured to be 50 s for 1% H-2. The proposed device concept can also be used to detect different chemical gases by using appropriate sensing layers.
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    Optical sensor for hydrogen gas based on a palladium-coated polymer microresonator
    (ELSEVIER SCIENCE SA, 2015) Eryurek, Mustafa; Karadag, Yasin; Tasaltin, Nevin; Kilinc, Necmettin; Kiraz, Alper
    We report an integrated optical sensor of hydrogen (H-2) gas employing an SU-8 polymer microdisk resonator coated with a palladium (Pd) layer and coupled to a single-mode optical waveguide. The sensing mechanism relies on the expansion in the Pd lattice due to palladium hydride formation in the presence of H-2. Strain induced in the microresonator then causes a red shift of the spectral positions of the resonator whispering gallery modes (WGMs) which is monitored using a tunable laser coupled to the waveguide. H-2 concentrations below the flammable limit (4%) down to 0.3% could be detected in nitrogen atmosphere at room temperature. For H-2 concentrations between 0.3 and 1%, WGM spectral positions shifted linearly with H-2 concentration at a rate of 32 pm/% H-2. Average response time of the devices was measured to be 50 s for 1% H-2. The proposed device concept can also be used to detect different chemical gases by using appropriate sensing layers. (C) 2015 Elsevier B.V. All rights reserved.