High-density magneto-optical disk using domain wall displacement detection

摘要

Domain wall displacement detection (DWDD) is the promising method for achieving very high-density magneto-optical disk. The resolving power can be expanded far beyond the optical limit which is determined by the light wavelength and the numerical aperture of the objective lens. Some technologies have been introduced to ensure the smooth wall motion which is the key to the high performance of DWDD. Very smooth surface is obtained by pretreatment of the substrate or by reactive ion etching process an a glass master. Reverse disk rotation for readout is effective in reducing the jitter because the front line for starting position of the wall displacement curves to the same direction as recorded crescent domains. A possibility of an areal density of 20 Gb/in~2 has been shown for the DWDD media using a blue-violet laser diode and an numerical aperture of 0.6.