| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to read a micro recording mark speedily and also stably by sequentially laminating a 1st protective layer, an optical or thermal active layer, a 2nd protective layer, an optical recording layer, and a 3rd protective layer on a transparent substrate loading a compressed stress on the 2nd protective layer for enabling it to reproduce near field light, and controlling an aperture diameter of micro apertures generated in the active layer. SOLUTION: A size of micro apertures generated in an active layer is to be decided by a stress from a 2nd protective layer. When a stress acting on the 2nd protective layer is a compressive stress, the micro aperture is hard to open, and even when it opens, the diameter of the micro aperture becomes small when the compressive stress from the 2nd protective layer is large. It is preferable that the compressive stress acting on the 2nd protective layer is within a range of 200 Mpa-1 Gpa. This compressive stress can be adjusted by growing conditions at the time of forming the 2nd protective layer. Thus, it is possible to control the aperture diameter of the micro apertures generated in the active layer by adjusting the compressive stress acting on the 2nd protective layer. |
