Tatsumi Ito

High Density Near-Field Optical Disc System

Key technologies for near-field recording/readout systems using a solid immersion lens (SIL) are summarized in this paper. Our system employing a SIL of 1.84 numerical aperture (NA) and a laser diode (LD) of 405 nm wavelength has realized the capacity of a 112 GB in a 12 cm diameter phase-change disc along with a write-power margin of ±11.2% and a data transfer rate of 36 Mbps. Such a larger-capacity data storage system should provide a high data transfer rate. A preliminary result of 1.84 NA dual-channel near-field recording/readout using a monolithic dual-beam LD with 412 nm wavelength is presented.

Head Analysis in Air Flow on Near-Field Optical Disk System with 2-Axis Actuator

Several near field optical disk systems have been proposed and are expected to be the tools for realizing large-capacity optical disk storage systems. However, there remains a concern as to whether removability can be realized in near-field optical disk systems. To resolve this concern, we analyze a near-field optical head installed onto a 2-axis actuator in an air flow. Finally, we conclude that a conical head and the active servo of a 2-axis actuator contribute to the stability of near-field playability with respect to dust robustness.