Two surface plasmon resonance dips in reflectance angular spectrum for a p-polarized incident beam of a [prism/Ag/SiO(2) helical thin film] Kretschmann configuration are measured and compared with simulations. The simulation also shows that the angular positions of resonances due to surface plasmon waves in reflectance spectrum are sensitive to the variation of principal refractive indices of helical films. It indicates that multiple surface plasmon waves at the [Ag/SiO(2) helical thin film] interface is more attractive than the traditional method of producing only one surface plasmon wave for chemical-and bio-sensing applications. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.