A Magneto-Optical Disk for Readout Using Circular Dichroism Effect

A magneto-optical disk for readout based on the circular dichroism effect was investigated. Making use of this effect, the optical head construction can be simplified, because recorded bits are directly detected as the change in intensity of reflected light. We studied multilayer structure films as a means of enhancing the circular dichroism, and identified as promising a four-layer magneto-optical medium consisting of AlN, GdTbFe, AlN and Al. The readout signal quality was evaluated using an optical head, and a C/N ratio of 45 dB was achieved at a bit length of 1.3 μm.