Surface Plasmon Resonance-Based Fiber-Optic Hydrogen Gas Sensor Utilizing Indium-Tin Oxide (ITO) Thin Films

We report experimental study on an indium-tin oxide (ITO)-coated surface plasmon resonance-based fiber-optic hydrogen gas sensor operating at room temperature. The sensor works on intensity modulation interrogation. Indium-tin oxide (In2O3 + SnO2) films were grown on unclad core of the fiber by thermal evaporation technique. The surface plasmon resonance (SPR) spectra for 100 % nitrogen gas as well as for a mixture of 4 % hydrogen gas and 96 % nitrogen gas were obtained. In the case of mixture of hydrogen and nitrogen gases, a sharp dip in the SPR spectrum was observed implying that the hydrogen gas changes the dielectric properties of ITO. The performance of the sensor has been studied for different percentages of tin oxide in indium oxide and for different thicknesses of ITO film. Both the parameters have been optimized for the best performance of the sensor.