title: Hydrogen sensing with Pd-coated long-range surface plasmon membrane waveguides.
abstract: A low power, reusable optical hydrogen sensor using long-range surface plasmon polariton (LRSPP) cladded membrane waveguides is demonstrated. The sensor incorporates a 5 μm wide, 20 nm thick gold stripe embedded in a 160 nm thick free-standing Cytop membrane with a 5 nm thick Pd over-layer. Input and output coupling is achieved with directly integrated broadside grating couplers. The sensor is tested with hydrogen concentrations up to 3% and demonstrates a strong response with an estimated detection limit of 290 ppm, and a response time of 7 s to a 0.6% H2 step - this level of performance is among the best reported for optical H2 sensors. Cycling of the hydrogen exposure shows a significant hysteresis response, however no film deformation or delamination was observed over many cycles. The high stress that is induced in clamped films during hydrogenation is relaxed in due to the film being deposited on the flexible and elastic Cytop membrane. This could result in improved lifetimes for this sensor and increased uptake ability.
authors.affiliation: Department of Electronics, Carleton University, Ottawa, Ontario K1S 5B6, Canada. nofong@doe.carleton.ca.
authors.forename: Norman R
authors.initials: NR
authors.lastname: Fong
authors.affiliation: School of Electrical Engineering and Computer Science, Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada and Centre for Research in Photonics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Berini
authors.affiliation: Department of Electronics, Carleton University, Ottawa, Ontario K1S 5B6, Canada. nofong@doe.carleton.ca.
authors.forename: R N
authors.initials: RN
authors.lastname: Tait