Optical and Magneto‐optical Characterization for Multi‐dimensional Multi‐level Optical Recording Material

We have proposed a new concept of multi‐dimensional multi‐level (MDML) optical recording. The MDML recording method fully makes use of the different light parameters to achieve ultra‐high density. An example of MDML is to use both intensity and polarization for the multi‐level signals. The samples used for this experiment have a multilayer nanostructure that contains a chalcogenide phase change material and a magneto‐optical material that corresponds to reflectance modulated by phase change and polarization changed by magnetic field, respectively. These films were deposited on to a 0.6 mm planar polycarbonate substrate by magnetron sputtering. A MDML static tester, with a simple design using a Wollaston prism and two photo‐detectors, has been developed to characterize both reflectivity and polarization of the MDML optical recording materials. The performance of such recording materials was further studied using this static tester. The influence of different film thickness and argon flow rate on the magnitude of polarization signal, coercivity and reflectivity were studied. Optical properties, e.g. refractive index, extinction coefficient, and optical transmittance of recording materials, were also measured.

Keywords:

• chalcogenide phase
• change material
• magneto‐optical material
• optical recording

The authors would like to express their appreciation to Dr. Sofian M. D. for helpful discussions and kind technical assistance.