The present invention relates generally to embedding andor encoding auxiliary information within original data. Each ring is pivotably coupled to each other in a manner such that the rings can be pivoted between a closed position where the front surfaces of the rings contact each other, and an opened position where the rings are positioned side-by-side in the same plane. The laser source has a coherence length. The sidewall may penetrate the second and third insulating layers to extend to the first insulating layer, and the sidewall may be tapered with respect to the main surface of semiconductor substrate.