AbstractRF-magnetron sputtered thin films of silver oxide (AgOx) were recently applied to ultra-high density optical data storage. It has been elucidated that the AgOx film sandwiched by protection layers shows very attractive characteristics in strong light-scattering, local plasmon generation and super-resolution by focussing a laser beam on it. Especially, the combination with an active recording film (optical phase change or magneto-optical) used in the currently recordable optical disks improves the storage density and overcomes the diffraction limit. In this paper, we describe the basic characteristics of nano-scale light scattering centers generated in the AgOx films and the interaction with ultra-high density recorded mark patterns in a near-field region. In addition, we provide the structural transition of the AgOx film by thermal and laser annealing treatment.