Low Contrast Sub-wavelengths Grating Lenses

ABSTRACTIn this work, we have demonstrated the light concentration from zero-contrast gratings (ZCG) subwavelength structures and compared the light concentration properties of previously proposed high-contrast gratings (HCG) to the ZCG micro concentrating lenses. To address the challenges of potential HCG fabrication, the difference between ZCG and HCG micro lenses is investigated numerically and found both of these subwavelength grating structures have similar light concentration characteristics. To gain deeper understanding of this phenomenon, we have explored the light concentration formation process and discussed the concentration mechanism in detail. Our work will be promising to provide a new ZCG micro lens potentially with easier and more controllable fabrication and could be utilized for various integrated nanophotonics applications, from optical cavities, read/write heads and concentrating photovoltaics.

Investigation of Perpendicular Magnetic Recording Footprint by Spin-Stand Microscopy

The characteristics of magnetic recording are necessary to understand in order to increase the areal densities and improve the perfermance of recording system. Therefore, experimental tools must be developed to help researchers to carry out signal and noise recording experiments on different heads and media combinations. In this paper, the perpendicular magnetic recording footprint using spin-stand microscopy is demonstrated. It was found experimentally that the magnetic footprint can precisely catch some recording dynamics of the write heads during the write gate off conditions and also provide useful insight information of the recording performance.

Materials and Processes in Heat Assisted Magnetic Recording

The conventional magnetic recording has approached its physical limits. Further growth of the areal density is limited by the superparamagnetic effect and by the limited possibilities to further improve write heads design and pole materials in order to enhance the writing field. A new technology proposed to surpass these limits is theheat assisted magnetic recording(HAMR). The principle of HAMR and the structure of a HAMR system are discussed, as well as the processes characterizing the writing process and the requirements for the materials needed for this type of recording. Some important challenges of the HAMR technology are summarized.