Tsuyoshi Toda

Write control method for high density magneto-optical disk system

In order to increase recording density, mark length recording is superior to mark position recording. However, in the case of magnetooptical media it is difficult to control mark edge position and shape because of its higher thermal conductivity. A new write control method using the multiple pulse write waveform is proposed, and it is shown that high density of 880 Mb/in/sup 2/ can be realized using this write control method. >

Polarization Control by Optical Feedback in Semiconductor Lasers

Control of the polarization state of semiconductor lasers is achieved by placing a polarizer in an external cavity. The TE and TM components of the laser beam are coupled with each other by the polarizer under optical feedback. The experimental results are explained by a coupled-mode model.

2 GB/130 mm Capacity Direct-Overwrite Magneto-Optical Disk

Precise mark-edge recording on a high signal-to-noise ratio (S/N) exchange-coupled direct overwrite magneto-optical (MO) disk provides 2 GB capacity on a 130 mm disk with a sufficient edge jitter margin. Write compensation technology was proven to be effective for both non- and direct-overwrite MO disks.

Write/Erase Cyclability of TbFeCo for Mark-Edge Recording

Write/erase cyclability for mark-edge recording is studied using rare-earth element[RE]-rich TbFeCo media. Mark-edge jitter for the (1-7) random pattern is small enough even after millions of cycles of data writing and erasing.

Application of Domain Transfer to Magneto-optical Recording: Domain Stabilization during Readout

The domain transfer phenomenon has been applied to light intensity modulated overwrite in order to obtain large power margin. By applying a suitable magnetic field to the multilayer before readout, recorded domains on the memory layer are transferred onto the writing layer. The application of domain transfer before readout improved the read power margin. However, an increase in noise was observed after irradiation of high read power. The reason for the noise increase was found to be an incomplete domain transfer. The incompleteness was successfully explained by introducing a domain nucleation model.

Detection of the Polarization Rotation of Reflected Light Using an Optical Feedback Effect in a Laser Diode

It is shown that the polarization state, the light-current characteristics and the terminal voltage of a buried-heterostructure laser are changed by altering the polarization direction of a laser beam which is reflected back on the laser diode itself. This phenomenon is utilized to detect time-varying polarization rotations of reflected light.