Stabilities of Laser Pumped Magnetic Field Modulation Recording

Direct overwriting and high density recording are key issues in optical recording. There are two optical recording methods i.e. (1) optical modulation recording and (2) magnetic field modulation recording. The optical modulation recording has more like optical oriented features to modulate laser beam with data while DC magnetic field is applied. The recorded mark size are limited by the diffraction optical spot size λ/2NA and complex media are necessary to comply with the demand of direct over writing. The magnetic field modulation recording method on the other hand has more magnetic oriented features to modulate magnetic field with data while constant waveform (DC or pulse train) laser irradiation is applied. The recorded mark size are limited by the magnetic field response applied and not limited by the optical spot size. The DC laser irradiation type has been used at Mini Disk™ and Laser pumped type has been used at HS ™ 3.5inch 650MB capacity magneto-optical drive. Moreover complex media are not necessary to comply with the demand of direct over writing, therefore the media applied magnetically induced super resolution(MSR) can be used easily.