Masaki Mukoh

Layer-Selection-Type Recordable Optical Disk with Inorganic Electrochromic Film

We have introduced a tungsten oxide film to a layer-selection-type recordable optical disk (LS-R) as an inorganic electrochromic (EC) film. The EC film showed a large transmittance change in a wide wavelength range. Layer selection was demonstrated with a dual-layer disk whose spacing was 0.3 µm, and the capacity of a 20-layer LS-R was estimated to be 1 TB.

Non-contact Deformable Mirror Actuator for Spherical Aberration Compensation

We have proposed and demonstrated a novel non-contact electromagnetic deformable mirror actuator for spherical aberration compensation with simple configurations. The magnetic ring with low stiffness placed on a mirror deformed the mirror into an ideal parabolic shape by applying a magnetic force generated from an electromagnet underneath. We were able to control the deformation of the mirror by adjusting the applied voltage. The maximum deviation from ideal shape was less than 30 nm. In addition, a continuous change of the defocus aberration proportional to the 1.5-λRMS/µm deformation of the mirror was achieved.

Optical Characteristics for Layer Selection Recordable Optical Disk

We introduced an inorganic electrochromatic layer for layer selection recordable optical disk (LS-R) by applying voltage. The material showed a large transmittance change in a wide wavelength range. The cross-talk between layers was sufficiently low.

Light-Propagation-Efficiency Evaluation Method by Using a Pinhole for Heat-Assisted Magnetic Recording

To evaluate the optical properties of a laser light through a waveguide, a pinhole layer was fabricated on an air-bearing surface of a slider. The pinhole layer consisted of a chromium thin film with a thickness of 160 nm. The pinhole (with diameter of 2 μm) was fabricated by dual-layer lift-off. The light-shielding effect of the pinhole layer was verified. The stray light outside of the pinhole was 0.18% of the light through the pinhole when the power of laser diode was 50 mW. The experimentally measured light-propagation efficiency of the waveguide was 83% of the design value.