Method and apparatus for recording and reproducing information on and

Abstract

The optical density and/or the reflectivity of a recording layer included in an optical disk is selectively changed to record information by irradiation with a semiconductor laser beam, while the recording layer may be covered with a suitable protective film. The thickness of the recording layer is so determined that it is able to record information by means of a continuous wave type semiconductor laser beam, while the optical absorption rate of the recording layer is adjusted by setting the percentages of particular additives. The recorded information may be reproduced by the application of a laser beam, the incident power of which is lower than that of the recording beam, to detect the reflected light.