Abstract: An optical information recording medium and a method of mastering an optical information recording medium. Cross-talk is avoided even when phase pits flanking a groove are radially aligned so that preformat information can be reliably reproduced after information is recorded at the grooves. A phase pit that encodes preformat information for a groove is radially spaced from that groove by a partition wall but is connected to an adjacent groove. When mastering, respective first and second exposing light beams are used to form the grooves and the phase pits, and the spacing between the two beams and, therefore, the width of the partition walls in the radial direction is precisely and easily controlled by controlling the inclination angle of at least one of the beams relative to an objective lens in the mastering exposure system.

Abstract: The invention concerns a method for optical recording of data on a photosensitive storage medium, characterized in that the data are encoded according to different possible states for the various components of a non-linear susceptibility tensor of the photosensitive medium and it consists in irradiating simultaneously at least a point of said support with write beams whereof the polarization is controlled for optical recording of a given non-linear susceptibility tensor on the photosensitive medium.