Optical storage devices, such as compact disk (CD) and digital versatile disc (DVD), provide us a platform for cheap and compact information storage media. Nowadays, information we obtain every day keeps increasing, and therefore how to increase the storage capacity becomes an important issue. In this paper, we reported a method for the increase of the capacity of optical storage devices using metallic nano-structures. Metallic nano-structures exhibit strong variations in their reflectance and/or transmittance spectra accompanied with dramatic optical phase modulation due to localized surface plasmon polariton resonances. Two samples were fabricated for the demonstration of storage capacity enhancement through amplitude modulation and phase modulation, respectively. This work is promising for high-density optical storage.