AN OPEN-RESONATOR MODEL FOR THE ANALYSIS OF A SHORT EXTERNAL-CAVITY LASER DIODE AND ITS APPLICATION TO THE OPTICAL DISK HEAD

Based on the open resonator theory, a model or a complex coupling coefficient suitable for the analysis of an ultrashort external-cavity laser diode is presented. It is shown that the effective reflectivity of the short external-cavity laser diode calculated by using this model is a function of the size of the laser-emitting area and is significantly influenced by the phase-modification factor as well as by the amplitude-reduction factor of the complex coupling coefficient. The calculated output power characteristics show good qualitative agreement with experimental observation. The necessary condition that the optical disk head using an external-cavity laser diode does not fail to detect the recorded signal for a broad range of flying height is also derived.