Initialization of phase-change optical recording medium

A method of initializing a phase-change optical information recording medium, comprising the steps of:

• providing a semiconductor laser device;
• providing an optical system including said semiconductor laser device configured to be utilized for initializing said phase-change optical information recording medium;
• and
• irradiating at least a part of said phase-change optical information recording medium by means of light beams emitted from said semiconductor laser device;
• wherein,
• in the spatial distribution of the semiconductor laser power focused on said recording medium in the direction perpendicular to guide tracks, said semiconductor laser device has an average in a first end region with a first predetermined width, and a second end region with a second predetermined width, of the width at half maximum of the spatial distribution, smaller than an average in the center region of the full width at half maximum of the spatial distribution.