BigPatents India

A write-once information recording disk has a transparent substrate having concentric or spiral grooves formed therein, and a recording film 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 wave-length 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 reflectively than the light reflectively of the recording film before irradiation with the short wavelength laser light. Therefore, the write-once type optical disk has a so-called low-to-high characteristic, that is, the reflectivity is higher after recording than before recording.