The optical propagation property of a planar waveguide with a periodic nanoparticle grating layer is characterized by using sliding prism method. Here, Cu nanoparticle grating was fabricated on a-SiO2 substrate by periodic heavy-ion irradiation technique. The pitch of these gratings was 2 mu m and 3 mu m, respectively. The flux and fluence were at the range of 6-10 mu A/cm(2) and 6 x 10(16)-1 x 10(17) ions/cm(2). respectively. The grating effect, mainly including the mode selection effect, is observed. The effect depends on the pitch of the grating and the morphology of nanoparticles. The propagation loss of the waveguide induced by nanoparticle layer is evaluated. (C) 2008 Elsevier Ltd. All rights reserved.