OPTICAL RECORDING MEDIUM, LIGHT CONTROLLER AND LIGHT CONTROL METHOD

摘要

In an optical disc and the like, there exists a limit in the recording quantity of an optical disc having a certain diameter, due to the available optical wavelength and the number of apertures of a condenser lens, since there is an minimum value in the focused beam waist diameter determined by the optical wavelength and the number of apertures (NA) of the condenser lens used. This invention provides an optical disc which provides a small beam waist diameter by eliminating such limit and a controller for such optical disc. A thin (mum order) saturation nonlinear refraction index medium layer (5) is provided directly after a plastic layer (4) and directly before a recording layer (6) of the optical disc.