Shinichi Kai

High-Resolution Blue-Laser Mastering Using an Inorganic Photoresist

An inexpensive and practical mastering technology was developed using a blue-laser optical system with a wavelength λ of 405 nm and numerical aperture (NA) of 0.95 comprising an inorganic photoresist. The resist system showed a higher resolution for a successful 130 nm pit patterning than that obtained by an ordinary organic photoresist system. Based on this technology, a read only memory (ROM) disc with a recording capacity of 25.2 GB on a 120-mm-diameter surface was mastered at a high recording speed of 4.92 m/s. The disc showed a reasonable jitter value of 8.0% using a conventional equalizer, 4.6% using a limit equalizer and a push-pull signal using a conventional readout optical system of λ=405 nm and NA=0.85.

Over 15-GB Capacity Domain Wall Displacement Detection Magneto Optical Recording Using a Digital Versatile Disc Dimensional Optical Head.

High-density magneto-optical (MO) recording using a land/groove structured domain wall displacement detection (DWDD) medium has been achieved with a digital versatile disc (DVD) dimensional optical head including a 664-nm wavelength laser diode and a 0.60-NA objective lens. Due to the deep groove depth, easy domain wall displacement is obtained without the use of a track boundary postannealing process. Sufficient readout performance is obtained in experiments at an areal recording density of 11 Gbit/inch2, which is obtained using a 0.13-µm bit length and a 0.45-µm track pitch. This areal density corresponds to a capacity of 15 GB per one 120-mm-diameter disk.

Detection of Readout Signals on High-track Density MO-Disk Using an Optical Phase Shifter and Deep Land/groove Recording

We report the results of magneto-optical (MO) detection using an optical phase shifter and a deep land/groove disk. We measured the recording characteristics in the direction of incident linear polarization and found that polarization perpendicular to the groove is best for a deep groove disk. Using perpendicular polarization, with a 693 nm wavelength diode laser and a 0.55-NA objective lens, sufficient readout and recording margins to guard against optical errors were obtained by the experiments at an area density of 3.69 Gbit/in2, which was obtained using a 0.35-µm bit length and a 0.5-µm track pitch.

Huge capacity optical memory using DWDD-MO recording

We improve the linear density and the user data-transfer rate, simultaneously. To achieve this aim, we prepared a wide-land structured domain wall displacement detection (DWDD) optical storage disk with a low dropout rate instead of using the land/groove structured disk of the previous study. In addition, we employed 8-9 modulation for the data modulation code instead of (1,7)RLL if the dropout rate rate was low.

High resolution blue laser mastering with inorganic photoresist

An inexpensive and practical mastering technology was developed by using blue laser optics of 405 nm in wavelength /spl lambda/ and NA=0.95 with an inorganic photoresist. The resist system showed a higher resolution for successful 130 nm pit patterning than that of ordinary organic photoresist systems. Based on this technology, a ROM disc with a recording capacity of 25 GB on a 120 mm diameter surface was mastered at a fast recording speed of 4.92 m/s. The disc showed a reasonable jitter value of 9.3% and a push-pull signal by using conventional readout optics of /spl lambda/=405 nm and NA=0.85.

Greater than 15-GB-capacity DWDD-MO recording using a DVD dimensional optical head

A new class of super resolution method was proposed for magneto-optical recording by T. Shiratori et.al. The method called DWDD (Domain Wall Displacement Detection) is principled on momentary magnetic wall displacement during a read-out.