INFORMATION RECORDING MEDIUM, AND RECORDING/REPRODUCING METHOD USING THE SAME

摘要

Provided is an information recording medium (100) comprising an information layer (110) including a recording layer (115) containing at least one kind selected from Ge-Te, Sb-Te and Ge-Sb and capable of making a phase change, and two or more dielectric layers (117 and 118) arranged on the optically incident side with respect to the recording layer (115).  Further comprised is a transparent layer (102), which is arranged adjacent to the information layer on the optically incident side with respect to the information layer (110), which is made of a material transparent to the light and which has a refractive index (n) of 1.75 or more.  Of the two or more dielectric layers (117 and 118), a dielectric layer b (118) and a dielectric layer a (117) are arranged on the optically incident side in the two dielectric layers (117 and 118) from the side closer to the transparent layer (102).  In this case, the refractive index (n) of the transparent layer (102), the refractive index (nb) of the dielectric layer b (118) and the refractive index (na) of the dielectric layer a (117) satisfy the relations of nb a.  The information recording medium (100) is enabled to record or reproduce the information with the irradiation of a light by using the optical system of a numerical aperture (NA) > 1.