| abstract |
A write-once information recording disk (28) has a transparent substrate (20) having concentric or spiral grooves formed therein, and a recording film (24) formed on the grooves on the transparent substrate, wherein the recording groove has an anion portion and a pigment portion, being formed of one organic pigment of which maximum absorption wavelength region from the wavelength of short wavelength laser light to be emitted to the recording film is present at the longer wavelength side, a recording mark is formed on the recording film by irradiation with short wavelength laser light, and the recording mark has a higher light reflectivity than the light reflectivity of the recording film before irradiation with the short wavelength laser light. Therefore, the write-once type optical disk (28) has a so-called low-to-high characteristic, that is, the reflectivity is higher after recording than before recording. |