Fabrication　and　characterization　of　the　miniature　device　of　waveguide　grating-structures　(WGS)　on　the　end　facet　of　an　optical　fiber　are　demonstrated.　A　layer　of　ZnO　between　the　fiber　and　the　grating　structures　serves　as　the　waveguide.　The　fiber　is　used　to　direct　the　excitation　light　to　the　WGS　and　to　carry　the　signal　response　back　to　the　detection　system.　The　narrow-band　waveguide　resonance　mode　tunable　in　the　visible　spectrum　can　be　measured　through　the　fiber　in　both　the　transmission　and　reflection.　This　nanodevice　may　be　suitable　as　long-range　sensors　for　the　detection　of　refractive-index　changes　in　nontransparent　or　toxic　liquids.